ABSTRACT 
 
 
 
 
Title of Thesis: 
FIREFIGHTER PORTABLE RADIO 
CARRYING METHODS: POCKET OR 
STRAP? 
  
 Nicholas Brondum 
Masters of Science, 2022 
  
Thesis Directed By: Dr. James A. Milke 
Department of Fire Protection Engineering 
 
 
Firefighters rely on their portable radios daily for communication.  This project examines 
firefighter portable radios and their carrying methods.  Carrying methods such as radio pockets 
sewn into turnout gear and radio straps are examined with respect to carrying utility, thermal 
protection, and decontamination ability.  Information was gleaned from several firefighter line of 
duty death and ?near miss? reports, personal interviews, empirical testing, computational fire 
modeling, and previous studies.  Tests were conducted with radios carried in radio straps both 
above and below the turnout coat, as well as in the radio pocket.  Radios were exposed to a radiant 
heat flux determined from computational fire modeling via a radiant panel until the test radio was 
either unable to transmit or receive messages from another radio.  From this analysis, it is 
determined that wearing a portable radio in a radio strap under a turnout coat is the most efficient 
and safest way to carry a radio. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
FIREFIGHTER PORTABLE RADIO CARRYING METHODS: POCKET OR STRAP? 
 
 
 
by 
 
 
Nicholas Brondum 
 
 
 
 
 
Thesis submitted to the Faculty of the Graduate School of the  
University of Maryland, College Park, in partial fulfillment 
of the requirements for the degree of 
Masters of Science 
2022 
 
 
 
 
 
 
 
 
 
Advisory Committee: 
Dr. James A. Milke, Chair/Advisor 
Dr. Peter Sunderland, Professor/Committee 
Dr. Arnaud Trouv?, Professor/Committee 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
? Copyright by 
Nicholas Brondum 
2022 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Acknowledgements 
This project was extremely challenging, so the support that I received from several 
individuals was truly invaluable.  It is my regret that I will almost certainly omit those who assisted 
me with this effort.  I sincerely thank all of those who assisted with these efforts, and I will forever 
be in your debt.  However, there are a few individuals that I must mention. 
First, I would like to thank the members of the St. Rose and White Hall Volunteer Fire 
Departments.  The knowledge that you have passed on to me has been truly invaluable.  Without 
these two fire departments, this research would have never even been a concept.  I would also be 
remiss if I did not thank all the firefighters who were more than willing to provide me with an 
interview.  Your information was vital to this effort, and you all were truly my inspiration to 
continue this project.  It is my hope that your, and our brothers? and sisters?, passion and dedication 
for our profession never waver and that this research may in some way help to keep you safe. 
To my professors and peers at Eastern Kentucky University and the University of 
Maryland, I would like to thank you.  I would have never imagined that I would have the 
knowledge or opportunity to make the contributions to this field and I hope that I may continue to 
share the knowledge that you all have imparted upon me. 
To Roy Kent, thank you for inviting me into your home and programming several of the 
radios and giving me the radio system knowledge that I desperately needed for this effort.  Also, 
to Sean Duncan, I may have only been one small conversation at a large trade show, but your 
support meant more than you could know.  It is my hope that more companies who serve the fire 
service be run by individuals who care as much about our profession as you. 
To Tanya, Morgan, and Dave Wilson and the whole Aetna Hose Hook and Ladder 
company, I am forever in your debt.  Without your extremely generous donation of the turnout 
 ii 
coats, the physical testing would have been impossible.  Your support as well was truly 
inspirational. 
To Christopher Lau, Kristina Severa, and Allyson Willis: I would have never been able to 
complete this effort without your help during the empirical testing.  Thank you all for your fantastic 
ideas and support during the hours of rigorous testing processes.  While it may have seemed boring 
at times, hearing your passions through our radio conversations spurred the numerous all-nighters 
this project required. 
Finally, I will forever be in debt to my parents.  You both have supported me no matter 
where my endeavors have taken me, physically, spiritually, monetarily, and emotionally.  This 
project has been challenging on all of us, but I can say that you were there with me every step of 
the way.  I can say with certainty that I would not be where I am today without you.  Your support 
means more than I could ever articulate. 
 
 
 
 
 
 iii 
Table of Contents 
Acknowledgements ......................................................................................................................... ii 
Table of Contents ........................................................................................................................... iv 
List of Tables ................................................................................................................................. vi 
List of Figures ............................................................................................................................... vii 
Chapter 1: Introduction ................................................................................................................... 1 
1.1 Defining the Problem .......................................................................................................................... 1 
1.2 Carrying Methods ................................................................................................................................ 1 
1.3 Critical Incident Study......................................................................................................................... 4 
1.3.1 1999 Cherry Road, Washington D.C. .......................................................................................................... 4 
1.3.2 2007 Meadowood Court, Leesburg, VA Fire .............................................................................................. 6 
1.3.3 2007 Marsh Overlook, Woodbridge, VA Fire ............................................................................................. 8 
1.3.4 2007 Deutsch Bank Building, New York, NY, Fire .................................................................................. 11 
1.3.5 2008 North Carolina Incident .................................................................................................................... 13 
1.3.6 2008 Ohio Incident .................................................................................................................................... 15 
1.3.7 2010 Connecticut Incident ......................................................................................................................... 16 
1.3.8 2011 San Francisco, CA Fire..................................................................................................................... 18 
1.3.9 2012 Riverdale Heights, MD Fire ............................................................................................................. 19 
1.3.10 2014 Southwest Inn, Houston, TX Fire ................................................................................................... 20 
1.3.11 2017 Texas Strip Mall Fire ...................................................................................................................... 23 
1.3.12 Other Near Miss Incidents ....................................................................................................................... 24 
1.4 Current Regulatory Standards ........................................................................................................... 26 
1.4.1 Introduction ............................................................................................................................................... 26 
1.4.2 NFPA 1802: Standard on Two-Way, Portable RF Voice Communications Devices for Use by Emergency 
Services Personnel in the Hazard Zone .............................................................................................................. 27 
1.4.3 MIL-STD-810H ......................................................................................................................................... 29 
1.5 Fire Department Policies ................................................................................................................... 30 
1.6 Review of Previous Studies ............................................................................................................... 32 
1.6.1 Introduction ............................................................................................................................................... 32 
1.6.2 NIOSH/Tri-Data Report ............................................................................................................................ 33 
1.6.3 NIST TN 1477 ........................................................................................................................................... 33 
1.6.4 NIST TN 1474 ........................................................................................................................................... 36 
1.6.5 Fairfax County (VA) Fire and Rescue Department Study ........................................................................ 37 
Chapter 2: Radio Strap Solutions .................................................................................................. 41 
2.1 Introduction ....................................................................................................................................... 41 
2.2 Radio Strap Carrying Configurations ................................................................................................ 41 
2.3 Commercial Off the Shelf Solutions ................................................................................................. 42 
Chapter 3: Computational Fire Dynamics Modeling .................................................................... 46 
3.1 Introduction to FDS ........................................................................................................................... 46 
3.2 Radio Positions .................................................................................................................................. 47 
3.2.1 Pocket versus Strap.................................................................................................................................... 47 
 iv 
3.3 Fire Scenarios .................................................................................................................................... 48 
3.3.1 Living Room .............................................................................................................................................. 48 
3.3.2 Bedroom .................................................................................................................................................... 68 
3.4 Heat Flux Selection ........................................................................................................................... 83 
Chapter 4: Empirical Testing ........................................................................................................ 85 
4.1 Introduction ....................................................................................................................................... 85 
4.2 Testing Methodology ........................................................................................................................ 85 
4.2.1 Test Set Up ................................................................................................................................................ 85 
4.2.2 Testing Process .......................................................................................................................................... 88 
4.2.3 Test Matrix ................................................................................................................................................ 90 
4.3 Testing Results .................................................................................................................................. 92 
4.3.1 Radio Pocket Testing ................................................................................................................................. 92 
4.3.2 8 ???2 Radio Strap Testing .................................................................................................................. 115 
4.3.3 12 ???2 Radio Strap Testing................................................................................................................ 126 
4.3.4 Exterior Radio Strap Testing ................................................................................................................... 135 
4.3.5 Analysis of Repeated Use Radios ............................................................................................................ 141 
4.3.6 Notes on Turnout Coats ........................................................................................................................... 142 
4.3.7 Summary of Failure Times and Temperature .......................................................................................... 145 
Chapter 5: Conclusions ............................................................................................................... 148 
5.1 Final Thoughts ................................................................................................................................. 148 
5.2 Experimental Program Comments .................................................................................................. 148 
5.3 Recommendations to Firefighters ................................................................................................... 149 
5.4 Recommendations to Fire Department Policy Makers.................................................................... 150 
5.5 Suggestions for Future Research ..................................................................................................... 152 
Appendices .................................................................................................................................. 154 
Appendix A: Living Room FDS Simulation Input File ........................................................................ 154 
Appendix B: Bedroom FDS Simulation Input File ............................................................................... 158 
Bibliography ............................................................................................................................... 161 
 
 v 
List of Tables 
Table 1.1: Thermal Classes as Reproduced From NIST TN 1474 and NIST TN 1477 ............... 34 
Table 1.2: NIST TN 1477 Class III Thermal Soak Results .......................................................... 36 
Table 3.1:Radio Positioning Survey ............................................................................................. 47 
Table 3.2: Living Room Simulation Important Material Properties ............................................. 51 
Table 3.3: Living Room Simulation Equation 1 Analysis for Radiative Heat Flux ..................... 63 
Table 3.4: Living Room Simulation Equation 3 Analysis for Radiative Heat Flux ..................... 64 
Table 3.5: Bedroom Simulation Important Material Properties ................................................... 70 
Table 3.6: Bedroom Simulation Equation 1 Analysis for Radiative Heat Flux............................ 79 
Table 3.7: Bedroom Simulation Equation 3 Analysis for Radiative Heat Flux............................ 80 
Table 4.1: 12 ???2 Radio Pocket Test Matrix .......................................................................... 91 
Table 4.2: 8???2 Radio Strap Test Matrix ................................................................................ 91 
Table 4.3: 12???2 Radio Strap Test Matrix.............................................................................. 91 
Table 4.4: Exterior Radio Strap Test Matrix ................................................................................ 92 
Table 4.5: Radio Pocket Failure Time and Temperatures .......................................................... 110 
Table 4.6: Total Average Pocket Time vs. Tempearture Data ................................................... 112 
Table 4.7: 8 ???2 Radio Strap Exposure Failure Time and Temperatures ............................. 122 
Table 4.8: Total Average 8 ???2 Radio Strap Time vs. Tempearture Data ............................ 125 
Table 4.9: 12 ???2 Radio Strap Failure Time and Temperatures ........................................... 133 
Table 4.10:  Total Average 12 ???2 Radio Strap Time vs. Tempearture Data ...................... 135 
Table 4.11: Exterior Radio Strap Failure Time and Temperatures ............................................. 140 
Table 4.12: Average Failure Temperatures for Exterior Radio Strap Tests ............................... 140 
Table 4.13: Results of Radios Used in Two Tests ...................................................................... 141 
Table 4.14: Results of Radios Used in Four or More Tests ........................................................ 141 
Table 4.15: Total Radio Failure Time and Temperatures ........................................................... 146 
 vi 
List of Figures 
Figure 1.1: Fire Equipment Evaluator (FEE) Schematic from NIST TN 1477 ............................ 35 
Figure 2.1: Radio Strap Comparison ............................................................................................ 44 
Figure 2.2: Commercially Produced Leather Radio Strap Mass .................................................. 44 
Figure 2.3: Handcrafted Leather Radio Strap Mass...................................................................... 44 
Figure 2.4: Nylon Radio Strap Mass............................................................................................. 44 
Figure 3.1: Couch Example Simulation Heat Release Rate Curve ............................................... 49 
Figure 3.2: Living Room Exterior Corner View ........................................................................... 50 
Figure 3.3: Living Room Door View ............................................................................................ 50 
Figure 3.4: Dimensioned Living Room Simulation Overhead View ........................................... 50 
Figure 3.5: Living Room Simulation 30 Seconds ......................................................................... 52 
Figure 3.6: Living Room Simulation 60 Seconds ......................................................................... 52 
Figure 3.7: Living Room Simulation 90 Seconds ......................................................................... 52 
Figure 3.8: Living Room Simulation 120 Seconds ....................................................................... 52 
Figure 3.9: Living Room Simulation 150 Seconds ....................................................................... 52 
Figure 3.10: Living Room Simulation 180 Seconds ..................................................................... 52 
Figure 3.11: Living Room Simulation 210 Seconds ..................................................................... 53 
Figure 3.12: Living Room Simulation 240 Seconds ..................................................................... 53 
Figure 3.13: Living Room Simulation 270 Seconds ..................................................................... 53 
Figure 3.14: Living Room Simulation 300 Seconds ..................................................................... 53 
Figure 3.15: Living Room Simulation 330 Seconds ..................................................................... 53 
Figure 3.16: Living Room Simulation 360 Seconds ..................................................................... 53 
Figure 3.17: Living Room Simulation 390 Seconds ..................................................................... 54 
Figure 3.18: Living Room Simulation 420 Seconds ..................................................................... 54 
Figure 3.19: Living Room Simulation 450 Seconds ..................................................................... 54 
Figure 3.20: Living Room Simulation 480 Seconds ..................................................................... 54 
Figure 3.21: Living Room Simulation 510 Seconds ..................................................................... 54 
Figure 3.22: Living Room Simulation 540 Seconds ..................................................................... 54 
Figure 3.23: Living Room Simulation 570 Seconds ..................................................................... 55 
Figure 3.24: Living Room Simulation 600 Seconds ..................................................................... 55 
Figure 3.25: Living Room Thermocouple Tree Temperature versus Time Curves ..................... 56 
Figure 3.26: Living Room Simulation Limiting Elevation ........................................................... 56 
Figure 3.27: Living Room Plume Mass Flow Rate ...................................................................... 57 
Figure 3.28: Living Room Smoke Layer Temperature ................................................................. 58 
Figure 3.29: Bedroom Simulation Smoke Layer Interface Temperature ..................................... 59 
Figure 3.30: Living Room Smoke Layer Height .......................................................................... 59 
Figure 3.31: Living Room Simulation Heat Release Rate Curve ................................................. 60 
Figure 3.32: Living Room Heat Flux for Firefighter 1 ................................................................. 61 
Figure 3.33: Living Room Heat Flux for Firefighter 2 ................................................................. 61 
Figure 3.34: Living Room Heat Flux for Firefighter 3 ................................................................. 61 
Figure 3.35: Living Room Heat Flux for Firefighter 4 ................................................................. 61 
Figure 3.36: Living Room Heat Flux for Firefighter 5 ................................................................. 61 
Figure 3.37: Living Room Heat Flux for Firefighter 6 ................................................................. 61 
Figure 3.38: Living Room Heat Flux for Firefighter 7 ................................................................. 62 
 vii 
Figure 3.39: Living Room Heat Flux for Firefighter 8 ................................................................. 62 
Figure 3.40: Living Room Temperature versus Time for Firefighter 1 ........................................ 65 
Figure 3.41: Living Room Temperature versus Time for Firefighter 1 ........................................ 65 
Figure 3.42: Living Room Temperature versus Time for Firefighter 3 ........................................ 66 
Figure 3.43: Living Room Temperature versus Time for Firefighter 4 ........................................ 66 
Figure 3.44: Living Room Temperature versus Time for Firefighter 5 ........................................ 66 
Figure 3.45: Living Room Temperature versus Time for Firefighter 6 ........................................ 66 
Figure 3.46: Living Room Temperature versus Time for Firefighter 7 ........................................ 66 
Figure 3.47: Living Room Temperature versus Time for Firefighter 8 ........................................ 66 
Figure 3.48: Temperatures when Crawling with a Pocket and with a Strap ................................. 67 
Figure 3.49: Temperatures when Standing with a Pocket and with a Strap ................................. 67 
Figure 3.50: Crawling and Standing Temperatures with a Strap .................................................. 67 
Figure 3.51: Crawling and Standing Temperatures with a Pocket ............................................... 67 
Figure 3.52: Reproduced Heat Release Rate Curve with Simulation Heat Release Rate ............. 69 
Figure 3.53: Bedroom Simulation Exterior Left Corner View ..................................................... 69 
Figure 3.54: Bedroom Exterior Right Corner View ..................................................................... 69 
Figure 3.55: Bedroom Door View ................................................................................................ 70 
Figure 3.56: Dimensioned Bedroom Simulation Overhead View ................................................ 70 
Figure 3.57: Bedroom Simulation 30 Seconds ............................................................................. 71 
Figure 3.58: Bedroom Simulation 60 Seconds ............................................................................. 71 
Figure 3.59: Bedroom Simulation 90 Seconds ............................................................................. 71 
Figure 3.60: Bedroom Simulation 120 Seconds ........................................................................... 71 
Figure 3.61: Bedroom Simulation 150 Seconds ........................................................................... 71 
Figure 3.62: Bedroom Simulation 180 Seconds ........................................................................... 71 
Figure 3.63: Bedroom Simulation 210 Seconds ........................................................................... 72 
Figure 3.64: Bedroom Simulation 240 Seconds ........................................................................... 72 
Figure 3.65: Bedroom Simulation 270 Seconds ........................................................................... 72 
Figure 3.66: Bedroom Simulation 300 Seconds ........................................................................... 72 
Figure 3.67: Bedroom Simulation 330 Seconds ........................................................................... 72 
Figure 3.68: Bedroom Simulation 360 Seconds ........................................................................... 72 
Figure 3.69: Bedroom Simulation 390 Seconds ........................................................................... 73 
Figure 3.70: Bedroom Simulation 420 Seconds ........................................................................... 73 
Figure 3.71: Bedroom Simulation 450 Seconds ........................................................................... 73 
Figure 3.72: Bedroom Simulation 480 Seconds ........................................................................... 73 
Figure 3.73: Bedroom Simulation 510 Seconds ........................................................................... 73 
Figure 3.74: Bedroom Simulation 540 Seconds ........................................................................... 73 
Figure 3.75: Bedroom Simulation 570 Seconds ........................................................................... 74 
Figure 3.76: Bedroom Simulation 600 Seconds ........................................................................... 74 
Figure 3.77: Bedroom FDS Simulation Temperature versus Time Curves .................................. 74 
Figure 3.78: Bedroom Simulation Limiting Elevation ................................................................. 75 
Figure 3.79: Bedroom Simulation Mass Flow Rate...................................................................... 75 
Figure 3.80: Bedroom Smoke Layer Temperature ....................................................................... 76 
Figure 3.81: Bedroom Smoke Layer Interface Temperature ........................................................ 76 
Figure 3.82: Bedroom Simulation Smoke Layer Height from Temperature Data ....................... 77 
Figure 3.83: Bedroom Heat Flux versus Time for Firefighter 1 ................................................... 77 
Figure 3.84: Bedroom Heat Flux versus Time for Firefighter 2 ................................................... 77 
 viii 
Figure 3.85: Bedroom Heat Flux versus Time for Firefighter 3 ................................................... 78 
Figure 3.86: Bedroom Heat Flux versus Time for Firefighter 4 ................................................... 78 
Figure 3.87: Bedroom Heat Flux versus Time for Firefighter 5 ................................................... 78 
Figure 3.88: Bedroom Heat Flux versus Time for Firefighter 6 ................................................... 78 
Figure 3.89: Bedroom Heat Flux versus Time for Firefighter 7 ................................................... 78 
Figure 3.90: Bedroom Heat Flux versus Time for Firefighter 8 ................................................... 78 
Figure 3.91: Bedroom Temperature versus Time for Firefighter 1 .............................................. 81 
Figure 3.92: Bedroom Temperature versus Time for Firefighter 2 .............................................. 81 
Figure 3.93: Bedroom Temperature versus Time for Firefighter 3 .............................................. 81 
Figure 3.94: Bedroom Temperature versus Time for Firefighter 4 .............................................. 81 
Figure 3.95: Bedroom Temperature versus Time for Firefighter 5 .............................................. 81 
Figure 3.96: Bedroom Temperature versus Time for Firefighter 6 .............................................. 81 
Figure 3.97: Bedroom Temperature versus Time for Firefighter 7 .............................................. 82 
Figure 3.98: Bedroom Temperature versus Time for Firefighter 8 .............................................. 82 
Figure 3.99: Temperatures when Crawling with a Pocket and with a Strap ................................. 82 
Figure 3.100: Temperatures when Standing with a Pocket and with a Strap ............................... 82 
Figure 3.101: Crawling and Standing Temperatures with a Strap ................................................ 83 
Figure 3.102: Crawling and Standing Temperatures with a Pocket ............................................. 83 
Figure 4.1: Radio Pocket Testing Setup Front View .................................................................... 86 
Figure 4.2: Radio Pocket Setup Top View ................................................................................... 86 
Figure 4.3: Radio Pocket Testing Shoulder Microphone Protection ............................................ 87 
Figure 4.4: Radio Strap Protected by Coat ................................................................................... 87 
Figure 4.5: Radio Strap Beneath Coat Positioning ....................................................................... 87 
Figure 4.6: Exterior Radio Strap Positioning ................................................................................ 87 
Figure 4.7: Radio Pocket R1 Setup Image .................................................................................... 93 
Figure 4.8: Radio Pocket Test #1 Temperature Data .................................................................... 94 
Figure 4.9: Radio A.1 Pre-Test ..................................................................................................... 95 
Figure 4.10: Radio A.1 Post Pocket Test R1 ................................................................................ 95 
Figure 4.11: Radio A.1 Antenna Post Pocket Test R1 .................................................................. 95 
Figure 4.12: Radio A.1 Antenna Post Pocket Test R1 Close Up .................................................. 95 
Figure 4.13: Radio B Damage Before Removal ........................................................................... 97 
Figure 4.14: Radio B Antenna and Knob Melting ........................................................................ 97 
Figure 4.15: Radio B Close Up Damage Prior to Removal .......................................................... 97 
Figure 4.16: Radio B Damage After Removal.............................................................................. 97 
Figure 4.17: Radio B Damage Close Up After Removal.............................................................. 98 
Figure 4.18: Radio Pocket Test #2 Temperature Data .................................................................. 99 
Figure 4.19: Radio C Damage After Pocket Test R3.................................................................. 100 
Figure 4.20: Radio C Melting After Pocket Test R3 .................................................................. 101 
Figure 4.21: Radio C Screen Crazing After Pocket Test R3 ...................................................... 101 
Figure 4.22: Radio Pocket Test #3 Temperature Data ................................................................ 102 
Figure 4.23: Radio Pocket Test #4 Temperature Data ................................................................ 103 
Figure 4.24: Radio C.1 Damage After Pocket Test #5 Prior to Removal ................................... 104 
Figure 4.25: Radio C.1 Top View after Pocket Test #5 Prior to Removal ................................. 104 
Figure 4.26: Radio C.1 and Thermocouple Damage After Removal After Pocket Test #5 ....... 104 
Figure 4.27: Radio C.1 and Antenna Damage After Removal After Pocket Test #5 ................. 105 
Figure 4.28: Radio C.1 Damage Close Up After Pocket Test #5 ............................................... 105 
 ix 
Figure 4.29: Radio Pocket Test #5 Temperature Data ................................................................ 106 
Figure 4.30: Radio A.1 Damage Prior to Removal After Pocket Test #6 .................................. 107 
Figure 4.31: Radio A.1 Damage Post Removal After Pocket Test #6 ........................................ 107 
Figure 4.32: Radio A.1 Damage Post Removal After Pocket Test #6 ........................................ 107 
Figure 4.33: Radio A.1 Damage Close Up After Pocket Test #6 ............................................... 107 
Figure 4.34: Radio A.1 Top Damage After Pocket Test #6 ........................................................ 108 
Figure 4.35: Radio A.1 Knob and Antenna Melting After Pocket Test #6 ................................ 108 
Figure 4.36: Radio Pocket Test #6 Temperature Data ................................................................ 109 
Figure 4.37: Radio Pocket Failure Time and Temperature......................................................... 110 
Figure 4.38: Radio Pocket Test Temperature at Battery............................................................. 111 
Figure 4.39: Radio Pocket Test Face Temperatures ................................................................... 111 
Figure 4.40: Radio Model A (L) and C (R). ............................................................................... 113 
Figure 4.41: 8 ???2 Radio Strap Test #1 Temperature Data .................................................. 116 
Figure 4.42: 8 ???2 Radio Strap Test #2 Temperature Data .................................................. 117 
Figure 4.43: 8 ???2 Radio Strap Test #3 Temperature Data .................................................. 118 
Figure 4.44: 8 ???2 Radio Strap Test #4 Temperature Data .................................................. 119 
Figure 4.45: 8 ???2 Radio Strap Test #5 Temperature Data .................................................. 120 
Figure 4.46: 8 ???2 Radio Strap Test #6 Temperature Data .................................................. 121 
Figure 4.47: 8 kWm2  Radio Strap Failure Temperature vs. Time ............................................ 123 
Figure 4.48: 8 ???2  Radio Strap Temperature at Battery ...................................................... 124 
Figure 4.49: 8 ???2 Radio Strap Face Temperature ............................................................... 124 
Figure 4.50: 12 ???2 Radio Strap Test #1 Temperature ......................................................... 126 
Figure 4.51: Radio E.4 Thermal Damage After 12 Strap Test #2 .............................................. 127 
Figure 4.52: Radio E.4 Thermal Damage After 12 Strap Test #2 Close Up .............................. 127 
Figure 4.53: 12 ???2 Radio Strap Test #2 Temperature Data ................................................ 128 
Figure 4.54: 12 ???2 Radio Strap Test #3 Temperature Data ................................................ 129 
Figure 4.55: 12 ???2 Radio Strap Test #4 Temperature Data ................................................ 130 
Figure 4.56: 12 ???2 Radio Strap Test #5 Temperature Data ................................................ 131 
Figure 4.57: 12 ???2 Radio Strap Test #6 Temperature Data ................................................ 132 
Figure 4.58: 12 ???2 Radio Strap Failure Temperature vs. Time .......................................... 133 
Figure 4.59: 12 ???2 Radio Strap Temperature at the Battery ............................................... 134 
Figure 4.60: 12 ???2 Radio Strap Face Temperature ............................................................. 134 
Figure 4.61: 8 ???2 Exterior Radio Strap Test Temperature .................................................. 137 
Figure 4.62: Radio E.6 Damage After Removal After 12 Strap Outside Test #1 ....................... 138 
Figure 4.63: Radio E.6 Melting After 12 Strap Outside Test #1 ................................................ 138 
Figure 4.64: Radio E.6 Melting Close Up After 12 Strap Outside Test #1 ................................ 138 
Figure 4.65: 12 ???2 Exterior Radio Strap Test Temperature ................................................ 139 
Figure 4.66: Radio Strap Degradation Between Tests ................................................................ 143 
Figure 4.67: Nylon Radio Strap Label Melted After Testing ..................................................... 144 
Figure 4.68: Turnout Coat Radio Pocket Closure Degradation after Pocket Test #1 ................. 144 
Figure 4.69: Radio Strap and Reflective Trim Damage ............................................................. 144 
Figure 4.70: Radio Pocket Closure Dripping After Pocket Test #2 ........................................... 144 
Figure 4.71: Radio Pocket Closure Completely Degraded ......................................................... 145 
Figure 4.72: Radio Pocket Trim Degradation ............................................................................. 145 
Figure 4.73: Trim Degradation and Turnout Gear Discoloration ............................................... 145 
Figure 4.74: Trim Damage After Strap Tests ............................................................................. 145 
 x 
Figure 4.75: Failure Temperature at Battery and Failure Time Comparison ............................. 147 
 xi 
Introduction 
1.1 Defining the Problem 
 Firefighting is an inherently dangerous profession.  Working in a hazardous and strenuous 
environment with severely diminished senses can often result in firefighters becoming disoriented 
and separated from each other.  If firefighters are so separated that they cannot communicate 
verbally with each other, they can often use their portable radios to communicate with each other 
inside of the building, or outside.  While these radios are quite literally a lifeline for firefighters, 
like all components of firefighting protective equipment, these can experience catastrophic 
failures. 
 While these radios may experience signal degradation in the built environment, the 
hardware itself is also susceptible to failures, especially when exposed to heat.  Complicating this 
issue, unlike most components of firefighting equipment, most portable radios that are in use in 
the North American fire service were not designed for use in firefighting conditions.  Standards 
such as NFPA 1802 have been written to address this gap, but many fire departments have not 
been fortunate enough to adopt radios that follow this standard due to the cost of modern portable 
radios. 
1.2 Carrying Methods 
 In addition to hardware itself, firefighter personal behavior can also affect a portable 
radio?s ability to transmit.  One of the main behaviors that affects a radio?s ability to transmit is 
the way that the radio is carried.  Due to the requirement for firefighters to utilize heavy equipment, 
firefighters need their hands free.  Therefore, the options to carry these radios are limited.  As 
many fire departments began to issue radios to each firefighter, a pocket specifically designed for 
 1 
a portable radio was often added.  While each fire department ordering protective equipment can 
opt for these pockets to be placed wherever they like, these are usually located on the firefighters? 
chest.  While this area was traditionally underused for pockets on firefighter turnout gear, it was 
also located closer to the firefighter?s face.  Therefore, while the fire environment necessitates 
respiratory protection, those using their portable radios can communicate more clearly.  This 
position also allowed for the emergency button to be located closer to the firefighter?s head so that 
in a stressful emergency, a firefighter would be able to activate this button with ease.  Additionally, 
if a firefighter were to fall through a hole in a weakened roof or floor, their radio would not be 
exposed to the heat below.  However, as the fire departments are more frequently responding to 
types of incidents such as medical emergencies, other carrying methods were developed.  One of 
the most popular ways to carry a radio today was developed from these efforts: the radio strap. 
 Generally, a strip of leather or nylon, a radio strap is designed to be worn over a shoulder 
with the radio hanging down at the firefighter?s side.  This method allows firefighters to carry a 
radio when not wearing turnout gear, such as on medical incidents.  These straps can also be worn 
in conjunction with the turnout ensemble, although variations do arise.  Some firefighters prefer 
to wear their radio strap beneath their turnout coat, so that the radio and the speaker microphone 
cord are protected by the protective equipment.  However, other firefighters prefer to wear their 
radio above their coat allowing for easier access to change channels and volume.  Other 
discrepancies arise as to the height of the radio.  Some firefighters prefer to wear their radio closer 
to their waists, allowing for the entire radio assembly to be protected by the turnout coat if worn 
under the coat.  Other firefighters seek to wear their radios against their thighs, allowing for the 
speaker microphone cord to be protected by the coat while also allowing for access to the radio 
itself.  Finally, some firefighters wear their radios facing backward, meaning that the screen and 
 2 
the speaker diaphragm are worn facing the firefighter rather than facing the surrounding 
environment. 
 While the radio pocket and radio straps are the most common ways to carry a radio, they 
are certainly not the only way radios are carried.  A firefighter from Australia stated that he 
preferred to carry his radio in a similar location to a radio strap, but that his department would not 
issue a radio strap because, ?it?s to American.?  This firefighter explained that to achieve this 
positioning, he placed the radio in his turnout pants cargo pocket.  He attaches a speaker 
microphone to the radio and has the cord run below his turnout coat and turnout pants.  He has cut 
a small hole in the outer lining of the cargo pocket backing for the cord to extend up toward the 
collar where he allows the speaker microphone to hang unsecured. 
 Finally, it is important to note the actions that firefighters must complete while operating 
at an incident and the positions in which these actions are completed.  Operations such as 
advancing hose lines, searching for victims and fire, and removing trapped occupants are all 
generally best completed with a firefighter crawling.  Firefighters can use large skeletal muscles 
to advance hose lines and remove victims while also keeping them closer to the ground to find 
overcome victims.  This position is also taught to firefighters as the best position to use when 
working in zero visibility conditions as a firefighter can possibly find a compromised floor and not 
fall into a hole or down a staircase.  However, firefighters can often crawl in different positions.  
While crawling on ?all-fours? may be the most common, using a ?tripod? stance is growing in 
popularity.  While different firefighters may choose one method over the other due to personal 
preference, it is important to note in this study as it will mean that portable radios will be in 
different orientations.  For example, the firefighter working in a stance known as the ?tall tripod,? 
where the firefighter operates with his weight on one knee and his or her opposite foot in front of 
 3 
him, will have a radio in a radio pocket held with the antenna pointing straight up.  However, a 
firefighter on ?all-fours? will have his antenna pointing straight in front of him or her rather than 
vertically as desired by portable radio literature.  The effects of these different methods will be 
mentioned later in this report in the fire modeling chapter of this report. 
1.3 Critical Incident Study 
1.3.1 1999 Cherry Road, Washington D.C. 
 One of the most infamous basement fires in the American fire service occurred in 
Washington D.C. in 1999.  This fire, located on Cherry Road, resulted in the deaths of two 
firefighters and injured several others [12].  Seven crews and a chief responded to the fire initially 
before having four additional crews respond.  When the fire crew arrived, they noticed smoke 
showing from the front of the building where they moved to attack the fire.  As an additional crews 
arrived, a sliding glass door at the rear of the basement was opened to provide both better access 
as well as ventilation to the fire.  However, this allowed the fire to rapidly intensify, endangering 
the crews who were already engaged in attempting to extinguish the fire.  As another crew moved 
to this area, they noticed that the basement had become completely involved in fire and they moved 
to extinguish the fire.  This crew requested permission to attack the fire, but they were denied as 
the incident commander did not know the locations of all the crews.  However, for the crews inside, 
the situation had become untenable due to an extremely rapid increase in temperature.  One 
firefighter was able to locate the nozzle of a hose line where he directed the stream of water at the 
ceiling.  This firefighter was able to evacuate from the building, but the other two firefighters that 
were with him were unable to evacuate. 
 In the National Institute of Occupational Safety and Health (NIOSH) report on the fire, 
there are several recommendations to improve firefighter safety.  However, several of these 
 4 
recommendations are in direct response to the radio communication challenges that were 
experienced on this fire.  While the fire department?s radio system was designed in accordance 
with NFPA guidelines, several channels were close together and radio traffic ?bled through? to 
other channels.  However, individual firefighters were not equipped with their own portable radios.  
The practice of equipping each firefighter with his or her own portable radio is relatively new, as 
many fire departments have issued a single radio to a group of two firefighters, or one radio per 
crew as seen in this incident.  Recommendation #5 in this report states, ?Fire departments should 
ensure that personnel equipped with a radio position the radio to receive and respond to radio 
transmissions.? This recommendation references the times when an incident commander called 
interior crews who did not respond.  A lack of response was the reason that the crew that had 
reached the rear of the basement was denied permission to attack the fire as the incident 
commander could not determine the location of interior crews and they did not answer his radio 
transmissions.  In the commentary for this recommendation, the report also states, ?an officer in 
the photograph had his radio positioned in his front bottom pocket (approximately waist level) of 
his turnout coat.? This position is not very common in the modern United States fire service, due 
to the prevalence of dedicated radio pockets.  This position would likely increase the exposed 
length of the speaker microphone cord, leaving the radio vulnerable to a failure. 
 Another issue with the radio system was the specific frequencies used.  While the radio 
system was designed in accordance with the NFPA 1221 guidelines, many of the frequencies were 
located close together [33].  This was done to allow for a smaller footprint on the radio traffic in 
the national capital region.  However, because the frequencies were closer together, firefighters 
often experienced a ?bleedover? where radio traffic would be audible on a nonrelated channel.  
Firefighters also experienced interference from other agencies with the same problems.  It is 
 5 
believed that one of the officers who received a message from the incident commander but did not 
answer it never heard the message due to this ?bleedover.? The report also states in this same 
section that firefighters should receive a portable radio that is equipped with an emergency button.  
This button can be found on nearly all fire service radios for the purpose of transmitting emergency 
radio traffic.  These can be programmed to do various tasks, but generally they will open the 
firefighter?s microphone and allow him or her to transmit without holding the push-to-talk (PTT) 
button as normal.  Some radios are also programed to trigger emergency alarms at fire dispatch 
centers so that dispatchers can communicate the emergency to an incident commander who might 
be unable to receive the message.  Finally, on modern digital radios, these buttons may be 
programed to allow a user to bypass a ?busy? signal so that the firefighter has priority over others 
operating at the fire scene.  This issue will be discussed later in this section. 
1.3.2 2007 Meadowood Court, Leesburg, VA Fire 
The first incident discussed after 2000 is the 2007 Meadowood Court Fire in Leesburg, VA 
[43].  Firefighters were initially dispatched to a commercial fire alarm, but while responding, some 
units were redirected to a residential house fire.  The first arriving engine and ladder arrived and 
operated alone for several minutes at a two-story house with fire evident.  Two firefighters entered 
the house with a hose line while two others entered to search for potential victims.  The firefighters 
advanced to the second floor of the building, inadvertently passing fire burning on the first floor.  
When attempting to open the ceiling to expose the fire burning in the attic, the truck company 
firefighters exited and reentered the house with longer hooks due to the tall ceilings.  While a 
second hose line was being brought to the crews operating in the zero visibility conditions, the 
crews experienced an extremely rapid temperature increase.  They also noticed that the fire was 
extending from the first floor and onto the second floor.  The crews retreated to a bedroom and 
 6 
began to attack the fire that was blocking their egress.  While this was happening, the engine 
company officer attempted to notify the incident commander of the situation, but his portable radio 
was inoperable, possibly due to a dead or degraded battery.  In addition to the possible battery 
issue, the department?s internal investigation states, ?Analysis of the radio also revealed thermal 
damage and a separation of the lapel microphone from the radio.?  [43] 
Therefore, while the engine company officer was unable to transmit a MAYDAY, the truck 
company firefighter was able to transmit a MAYDAY message.  In response, the incident 
commander deployed the rapid intervention team to rescue the trapped firefighters.  The engine 
company attempted to open the hose line to cool the area, but they immediately lost water pressure 
due to the hose line being burned through.  Therefore, the engine company abandoned the hose 
line and sought refuge in a bedroom.  However, there was a partial collapse, separating the truck 
company officer from the other three firefighters.  The three other firefighters were able to evacuate 
from the second floor via an external ground ladder.  The truck company officer was also able to 
evacuate from a different side of the building.  It is reported that his truck company officer?s 
turnout gear was burning when he was rescued. 
 In response to this incident, a comprehensive review of the incident was conducted by the 
fire department.  Part of this analysis included both the radio traffic as well as the portable radio 
themselves.  Three of the trapped firefighters wore their radios in a radio strap while the fourth 
firefighter wore theirs in a radio pocket.  As previously mentioned, the engine company officer?s 
radio had failed.  The speaker microphone had both separated from the radio and it had melted to 
the turnout coat and the radio strap had melted to the self-contained breathing apparatus harness.  
According to the report, the radios carried in the radio straps all suffered thermal damage while 
the firefighter who wore their radio in the radio pocket did not experience any thermal damage. 
 7 
 Obviously, with this thermal damage and the hectic nature of the incident scene, the radio 
traffic was analyzed.  In this report, firefighters were ?stepped on? or ?covered,? meaning that two 
units attempted to transmit at the same time, making at least one message unintelligible.  This 
occurred four times during the initial confusion of which units would be responding as well as four 
additional ones afterward.  There were five ?garbled? or otherwise unintelligible messages before 
units arrived at the scene and ten afterward.  While the volume of units arriving and the complex 
nature of the incident would justify these errors, there were several microphone clicks, meaning 
that the radio attempted to transmit, either due to an inadvertent button push by the firefighter, or 
as an equipment malfunction.  None of these microphone clicks occurred before units arrived at 
the scene, but there were 74 microphone clicks while units operated at the scene.  These four 
firefighters were luckily able to escape the building.  However, one of their critical ?lifelines? to 
their fellow firefighters on the scene failed these firefighters. 
1.3.3 2007 Marsh Overlook, Woodbridge, VA Fire 
 In April of 2007, the Prince William County, Virginia, Fire Department responded to a 
two-story house fire during shift change at just after 6:00 AM [20].  When firefighters arrived, 
they saw fire showing from two sides of the building.  The company officers of the first two 
arriving units began to survey the entire scene by walking to the rear of the structure before 
determining a plan of action and entering the structure.  Firefighters assigned to the truck company 
entered the building and proceeded to the second floor to search for victims due to the presence of 
a locked door and a vehicle in the driveway.  The engine company deployed a 2 ? inch hose line 
into the building and called for water.  While the hose line was being charged with water, the 
interior conditions deteriorated nearly instantaneously.  The truck company firefighters on the 
second floor began to move to the stairs in response to these conditions.  Simultaneously, an order 
 8 
to evacuate the building was issued by the incident commander.  Due to the zero visibility 
conditions, the officer of the truck company stumbled across the stairs and fell down a few steps.  
He then directed the firefighter with him to follow him to the steps, but this firefighter was unable 
to do so.   
 Now that the 2 ? inch hose line had been charged with water, firefighters began to direct 
water upward toward the second floor to protect the truck company.  The truck company officer 
was able to exit the building but was stopped by the firefighters operating the hose lines.  The 
officer of a company assisting the engine with their hose line called a MAYDAY for the missing 
firefighter.  This transmission was then followed by the missing firefighter himself calling a 
MAYDAY.  More hose lines were deployed to flow more water into the area to provide refuge to 
the missing firefighter as well as other firefighters engaged in rescue efforts.  However, due to the 
intense heat, these firefighters were driven back.  The missing firefighter therefore could not be 
rescued despite numerous attempts.  The firefighter succumbed to his injuries at the scene. 
 In response to this incident, the Prince William County Fire Department diligently 
researched the incident.  Numerous recommendations were made regarding staffing and policies.  
However, research was also conducted with third parties.  The truck company officer?s and the 
deceased firefighter?s turnout gear were both analyzed by a third party, as were their self-contained 
breathing apparatus.  However, of particular interest to this study was an analysis of the portable 
radios carried by the firefighters. 
 During this incident, many firefighters, including the incident commander, stated that they 
were unable to communicate effectively through the duration of the incident.  While a complete 
radio transcript was not provided with this report, a timeline referencing several key messages is 
provided as an appendix to the referenced report.  During this incident, firefighters were ?stepped 
 9 
on? or ?covered? three times.  Transmissions that did not have to contend with these challenges 
also became garbled, unintelligible, or unclear in some way.  According to the fire department?s 
internal investigation, 26 transmissions were at least partially unintelligible.  However, most 
dramatic would appear to be what are shown as ?mic clicks,? in the transcript.  These could have 
been a firefighter who inadvertently pressed the PTT button, or it could be that the wires in the 
radio contacted one another, allowing the radio to transmit.  There were 87 distinct reports of ?mic 
clicks,? with many relaying, ?several mic clicks,? likely leading to over 100 of these incidents.  
Several firefighters also experienced a radio prohibit, or a ?busy? signal.  This signal is also 
colloquially known as a ?bonk,? and will be discussed in several of the following incidents.  
Furthermore, the report states, ?Numerous personnel reported operations problems with their 
portable radios.?  Six problems were stated including Transmission and Receiving failures, an ?out 
of range? radio, self-transmitting radios, dead batteries, and an ?inoperable radio.?  The report also 
states that nine firefighters experienced radio failures, with most of these firefighters either 
involved in the rescue efforts or in the hose line operations.   
 Another radio problem mentioned in this report states, ?Portable radios are extremely 
vulnerable to poor environmental conditions and interference of digital noise from ambient sources 
which negatively impact the ability of emergency personnel to effectively communicate.? [20]  
The report states that this finding is mainly linked to water damage, which was the inspiration for 
the radio test conducted in conjunction with this report. 
 An appendix of this report describes the process of firefighters exposing their radios to 
water simulating a heavy rain.  The firefighters wore their radios in a radio strap over their coat, 
limiting the radios? protection from the water.  These radios were coupled with various speaker 
microphones.  The speaker microphone, due to their unshielded positions at the firefighters? 
 10 
shoulder appear to have been most effected by the water deposits.  The testing evaluated if the 
emergency button would work as designed and programmed, despite the damaged speaker 
microphone.  This was largely confirmed to operate on all operations channels.  However, the open 
microphone feature, designed to keep the firefighter?s radio in the transmitting mode without any 
additional input for a set duration, could not operate once the transmission capabilities were 
eliminated.  It was also determined that the radios operated effectively with an untested speaker 
microphone.  Partially developed from this study, more advanced and more modern radios 
generally have better water resistance than older radios. 
 As a final note of interest from this incident, the firefighters? protective equipment was 
examined.  While the truck company officer was able to evacuate relatively quickly after the 
emergency evacuation order, his gear was damaged.  However, the deceased firefighter?s gear was 
far more damaged.  However, the statements in the appendix of the referenced report states that 
much of this damage likely occurred after the firefighter?s passing.  Therefore, if the firefighters? 
protective equipment could have received such significant damage, it is reasonable to state that the 
radio would need to be protected, either in the bunker coat pocket or in a radio strap worn under 
the firefighter?s turnout coat. 
1.3.4 2007 Deutsch Bank Building, New York, NY, Fire 
 In 2007, the Deutsch Bank Building fire in the Manhattan borough of New York City 
experienced a fire while it was undergoing demolition resulting from the damage inflicted by the 
September 11th attacks. [7]  While responding to this fire, two firefighters were trapped and 
succumbed to their injuries.  In addition to these two firefighters, 115 others were injured.  While 
many building fire protection systems were in various states of disrepair, firefighters also had 
significant communication challenges, leading to these injuries and fatalities. 
 11 
 When firefighters arrived, there was a miscommunication as to which fire department 
connection would supply the building?s standpipe system.  Unfortunately, the building?s standpipe 
system was inoperable due to the demolition efforts.  When the first companies ascended the 
building, they found that the stairwells had been blocked with hatches.  Firefighters worked to 
remove these hatches, and after a significant effort to remove these obstructions, firefighters 
encountered an intense fire.  Numerous other resources were summoned to attack the fire, which 
spread downward via plastic sheeting designed to separate portions of the building.  These 
obstructions made the building into a labyrinth for the firefighters.  Firefighters were also cut off 
by the downward spread of the fire.  As conditions deteriorated, firefighters worked to establish a 
water supply via a hose line on the building?s exterior.  Once firefighters were able to secure a 
water supply using this method, a fire attack commenced.  However, the firefighters who were 
operating this hose line ran out of air.  While these firefighters called a MAYDAY for assistance, 
others were called due to crews being separated.  Additionally, firefighters also declared 
MAYDAYs due to difficulties navigating around the obstructions in the building.  The firefighters 
who ran out of air were eventually removed from the building and transported to hospitals where 
they were pronounced dead. 
 While high-rise fires pose immense logistical challenges, the conditions in this building 
complicated this incident further beyond high-rise fires.  Overall, there were 13 MAYDAYs 
declared during the first hour and forty-five minutes of this incident.  Many of these were unique 
incidents, but some of these calls resulted from reports not being acknowledged.  Also, there were 
several urgent communications regarding missing firefighters.  Unfortunately, an incident with 
this many emergency messages would be extremely challenging for the best prepared and best 
equipped fire departments.  While these radio communication challenges were not related to radios 
 12 
failing, they do show how logistical challenges can dramatically complicate a fire response.  Had 
these firefighters not been able to communicate these emergency messages, more catastrophic 
consequences would have surely followed.  Furthermore, high-rises typically pose immense 
communication challenges, solely due to building construction features.  Therefore, these 
challenges will be dramatically complicated by the increased traffic resulting from similar 
emergencies. 
1.3.5 2008 North Carolina Incident 
 During this incident, two firefighters were killed and one severely injured [8].  Firefighters 
arrived at a commercial millwork facility to find a large fire.  Multiple crews entered the building 
to extinguish the fire, but they were evacuated from the building due to the deteriorating 
conditions.  However, crews soon reentered the building to contain the fire within the building to 
the office area rather than the production area.  However, while these firefighters were working, 
they experienced a radio failure.  When the group did not answer multiple radio messages from 
the officers outside, a rapid intervention team was dispatched to find and rescue the potentially 
trapped firefighters.  However, the group was not in danger, so the firefighter in charge of the 
interior team, a captain, sent another firefighter out of the building to report the position and recall 
the rapid intervention team.  The chiefs and the firefighter sent outside met before the firefighter 
reentered the building to rendezvous with the group.  However, while the chief was instructing the 
rapid intervention team that they were not needed, the firefighters inside noted that the fire was 
spreading extremely rapidly.  During this period, there were numerous unintelligible radio 
messages.  These messages could have been the interior crew requesting help, but this cannot be 
determined. 
 13 
 The two firefighters realized that they could not control the fire and they decided to 
evacuate the building.  However, the firefighters became disoriented and returned to the nozzle to 
use its water for protection from the intense fire.  While this was happening the captain again 
attempted to call for assistance, but he could not determine if anyone heard his message.  One 
firefighter who had reentered the building attempted to call the captain over the radio, but he could 
not reach the captain.  The captain who was attempting to release kinks in the hose line previously 
called for the firefighter at the nozzle to follow him and exit the building.  The captain also called 
a MAYDAY requesting assistance again, but he did not receive a response to either transmission.  
The captain began to evacuate the building where he found that the hose line had begun to leak.  
Due to the intense heat, the captain laid down next to the hose line so that the leaking water could 
cool him and provide protection from this intense heat. 
 Luckily, one of these MAYDAYs was heard and one of the rapid intervention teams was 
able to enter the building and rescue the captain.  However, the intense heat prevented them from 
advancing further along the hose line to rescue the other firefighters.  One of the firefighters was 
rescued in subsequent efforts, but the intense heat caused a substantial delay to reach the second 
firefighter.  Both firefighters were pronounced dead. 
 While there were several factors that lead to the untimely deaths of these two firefighters, 
the first factor mentioned in the NIOSH report of this incident is, ?intermittent radio 
communication problems (unintelligible transmissions in and out of the fire structure)?? [8]  In 
response to this factor, the report recommends that radio manufacturers should develop and refine 
radio systems working with firefighter protective equipment. 
 14 
1.3.6 2008 Ohio Incident 
 In a 2008 incident in Ohio, two firefighters were killed when they were trapped in a 
basement while attacking a fire [9].  The firefighters arrived and found a homeowner who informed 
the firefighters that the house was on fire.  In response to this information, the firefighters advanced 
a 1 ? inch hose line into the building to combat the fire.  When one of the firefighters called for 
water, his message was not heard by the firefighter at the engine.  However, after multiple attempts, 
another firefighter was heard.  When the captain and another firefighter reached the basement, they 
began to apply water to the fire while another firefighter assisted them moving the hose line.  Two 
other captains believed that they needed to reposition the hose line, but despite a radio call and one 
of the captains yelling to the crew inside, they did not receive a response.  Inside of the building, 
one firefighter saw the captain attempting to call a MAYDAY due to the intense fire, but despite 
3 efforts, the radio gave a ?busy? signal, preventing her from transmitting her messages.  The 
captain then instructed the firefighter to evacuate from the building, and that she and the second 
firefighter would follow.  However, they did not.  The firefighter who had evacuated attempted to 
rescue his crew, but he was unable to reach their position due to the heat.  He then reported the 
situation to his incident commander who attempted to reach the interior crew but could not.  Crews 
brought two hose lines with them to control and extinguish the fire, and when another crew arrived, 
another attempt was made to rescue the trapped firefighters.  This crew advised the commander 
that they believed that the fire was being fueled by the house?s natural gas and that the hose line 
that the crew had been using had burned about 18 inches near the nozzle.  These crews were able 
to remove the debris from both victims, who were both pronounced dead at the scene. 
 While this incident had far fewer contributing factors than many of the aforementioned 
incidents, one of the issues listed is the radio communication problems.  To address this factor, the 
 15 
NIOSH report makes a few key recommendations.  One is that, ?fire departments should ensure 
that radio operability guidelines follow best practices recommended by the International 
Association of Fire Chiefs.? The report also states, ?The communications network must integrate 
the equipment and procedures with the dynamics of the incident site, especially in terms of the 
environment and the human factors affecting its use.? [9]  The report also gives the same 
recommendation that radio manufacturers must work with fire departments to improve radio 
capabilities and designs. 
 This specific incident was also referenced in an article from FireFightingNews.com.  This 
article, published in 2011, discussed how several fire departments have experienced radio failures 
with digital radios that were new at the time.  These radios had been developed in the aftermath of 
the September 11th attacks with the goal of allowing several public safety agencies to communicate 
with each other.  However, the article states that firefighters are skeptical of the new technology 
and even states, ?Digital radio failures contributed to the deaths of at least five firefighters, the 
disabling of a sixth and scores of close calls.? [13].  While several incidents are discussed in this 
article, many discuss incidents that occurred due to, ?bonking.? These busy signals, named for the 
distinctive sound emitted from the radios, have been observed in numerous incidents.  Specifically 
referring to this incident, the article states, ?the trunked system rejected at least 43 attempted 
communications by firefighters.? 
1.3.7 2010 Connecticut Incident 
 Two firefighters were killed in a fire in a two and half story multiple family dwelling in 
2010 in Connecticut [10].  Firefighters arrived to find a building with a fire burning in a room on 
the second floor.  Firefighters quickly extinguished the fire in the room, but quickly noted that the 
fire had spread into the eves and into the attic space.  Due to the difficult to extinguish fire and 
 16 
outside temperatures above 90?F, many firefighters quickly exhausted their air supply.  As 
firefighters replenished their air, they reentered the building and resumed their firefighting duties, 
often with firefighters from other companies.  The fire, strengthened by the wind, eventually 
caused interior conditions to deteriorate.  Despite efforts to ventilate the building, visibility 
reduced, and the heat built up in the building.  Firefighters working at the building?s rear stairs 
became trapped and called a MAYDAY.  However, this message was not acknowledged by the 
incident commander or by the dispatch center.  More than three minutes after this message was 
broadcast, another firefighter encountered one of the firefighters who called the MAYDAY 
message.  This firefighter called his own MAYDAY for help to remove the endangered firefighter.  
This message was received by the incident commander, but not by the fire dispatch center.  While 
the rescuing firefighter eventually did receive assistance from other firefighters, it was quickly 
determined that a second firefighter was missing.  Another firefighter found his missing coworker 
and called a MAYDAY.  This message was not acknowledged, so he called for a second 
MAYDAY.  This third overall message was acknowledged by the dispatch center and this second 
injured firefighter was removed from the structure.  However, both firefighters were both 
pronounced dead at the hospital. 
While radio failures were not a factor in the deaths of these two firefighters, the failure to 
receive their messages likely did lead to their deaths.  The NIOSH report does not contain a 
comprehensive radio transcript, but rather summarizes important radio transmissions rounded to 
the nearest minute to construct an incident timeline.  This timeline provides a minimum of 29 
messages that were either partially unintelligible or were not acknowledged.  While the fluid and 
hectic incident scene would certainly justify these missed messages, this problem will be greatly 
magnified by damaged radios.  Therefore, while radio failures may not be responsible for the 
 17 
deaths of the firefighters, this incident highlights how important radio communications can be and 
how significant a failure in communications can be. 
1.3.8 2011 San Francisco, CA Fire 
 Firefighters responded to a four-story residential structure with two levels below grade and 
two above at the front of the building [11].  When firefighters arrived, they found light smoke 
coming from the first visible floor.  The first engine company deployed a 1 ? inch hose line into 
the building to the ?first floor.? This floor would be the third overall floor.  One of the chiefs 
arrived and had a face-to-face conversation with the engine company officer.  The two officers 
both believed that the fire was on the floor below them in the basement.  The chief stated that 
crews would attack the fire from a different side of the building before he retreated from the 
building.  The two firefighters on the hose line did not follow the chief.  It was believed that the 
crews advanced to the basement stairs, but after a basement sliding glass door was breached, the 
fire rapidly intensified, and overcame the crew on the hose line.  The two firefighters were 
transported to a hospital, but both were pronounced dead. 
 The building?s structure and the fire department tactics played a large role in this incident.  
However, the fire communication methods complicated the issue.  The NIOSH report issued in the 
wake of this incident provides a recommendation that fire departments and radio manufacturers 
need to work together to improve radio systems for firefighters.  The report states, ?During this 
incident, several issues occurred involving the radio, such as: garbled and unintelligible radio 
transmissions heard by the IC; the Mayday from BC6 being walked on by the dispatch; and the 
Victims? remote microphones being damaged by thermal environments.? [11]  The report did not 
state the way the firefighters were carrying their radios, but regardless of carrying method, the 
speaker microphone cord will be exposed to the fire environment.  While the radio pocket method 
 18 
exposes less of the speaker microphone cord to the environment than carrying the radio completely 
unprotected, it exposes far more of the cord than the radio strap arrangement. 
1.3.9 2012 Riverdale Heights, MD Fire 
 Firefighters responded and arrived to find a two-story single-family house [44].  An engine 
and two firefighters from a truck company entered the house.  However, due to the wind-driven 
basement fire, the firefighters on the engine company were forced out of the building.  However, 
the firefighters on the truck company did not know that they were left alone in the building.  These 
two firefighters attempted to return to the door, but they were unable to open the front door.  One 
of the two firefighters found a window and they attempted to climb through the window.  However, 
the first firefighter was unable to exit the window.  While the two trapped firefighters had called 
for the engine company several times, they called for a MAYDAY at the window [17].  To transmit 
this message through the large volume of radio traffic, the two firefighters activated the emergency 
features of their radios to override any other radio traffic.  The two firefighters sheltered in place 
for a short time, waiting for assistance to come from the firefighters outside the building.  However, 
when the message was not acknowledged, the second firefighter was able to climb through the 
window and get help from the building?s exterior.  The firefighter who remained trapped inside 
was able to move toward the front door.  Eventually the second firefighter, who had removed his 
respiratory protection to summon help in the front of the building, was able to force the front door 
open and rescue the still trapped firefighter.  Overall, seven firefighters were injured during this 
incident, and while two of the firefighters suffered near fatal injuries, all the firefighters were able 
to recover. 
 While the extreme heat in the building and the miscommunication between the truck and 
engine companies were two of the main causes of the injuries, there were also complications with 
 19 
the firefighter?s portable radios.  During the incident, there was a significant amount of radio 
traffic.  While there were numerous ?stealth rejects,? there were numerous radio messages that 
were garbled or otherwise ineffective.  In the transcripts of one radio channel used during the 
incident, there were 50 electronic garbles and other failed messages.  It should also be noted that 
despite the recording of the emergency activations, the MAYDAY and the requests for the hose 
line are not reflected in the transcripts. 
A second radio channel was also needed due to the emergency activations.  In addition to 
this complication, one of the trapped firefighters had the sheathing on his speaker microphone melt 
and the wires fuse together.  This caused an open transmitter, meaning that other firefighters could 
not transmit on this channel.  This firefighter as well as the other trapped truck company firefighter 
wore their radios in a radio strap over their coat.  In response to this finding, the report references 
the National Institute of Standards and Technology (NIST) report entitled Testing of Portable 
Radios in a Fire Fighting Environment [48] which guides firefighters to wear their radios in the 
radio pocket sewn into the turnout gear.  This report will be reviewed in detail in a following 
section of this report.   
1.3.10 2014 Southwest Inn, Houston, TX Fire 
 One of the most notable fires for radio traffic complications is the 2014 Southwest Inn fire 
in Houston, Texas [45].  This fire in a hotel caused the deaths of four firefighters at the scene, with 
a fifth succumbing to injury complications a few years later.  Firefighters arrived to find smoke 
showing from the front of the main hotel building.  The crews progressed into the building with a 
2 ? inch hose line.  They then requested that the next arriving engine company secure a water 
supply while they fought the fire.  As more crews arrived, they entered the building to support the 
first crew on the hose line.  One crew was also designed as a rapid intervention team while the 
 20 
crews worked inside.  The first challenge to the radio system documented in this report was that 
one of the firefighters working to attack the fire had a stuck microphone.  However, just after the 
incident commander attempted to contact the firefighter to alert them of the situation, there was a 
significant building collapse.  One of the crews inside called a MAYDAY for the now trapped 
crew.  Initially, there was confusion as to who the endangered crew were, as the crew that 
transmitted the MAYDAY message was not the crew that was now trapped.  The rapid intervention 
team was activated to find the missing firefighters while other crews were used to form a secondary 
rescue team.  As other crews arrived on scene, some were used to rotate with the crews who had 
been operating since the early portion of the incident while others were used to assist in the rescue 
efforts.  As firefighters worked to rescue their trapped comrades, one of the radios of the missing 
firefighters was activated.  This radio activated several more times, for a total of nine times.  This 
number is reflected in the transcripts, but the report later states that this sole radio activated over 
twenty times.  Due to this number of activations, it was believed that the firefighter had found an 
area of refuge, so firefighters continued to search for this firefighter.  However, after this firefighter 
was located and extricated from the building, the decision was made to shift from a rescue to a 
recovery mode.  Overall, four firefighters were killed and twelve were initially injured.  It is likely 
that had the errant radio activations not occurred, that there would have been fewer injuries to the 
firefighters involved in the rescue effort. 
 In response to this incident, the Houston Fire Department launched a rigorous investigation 
into several aspects of the incident, including the firefighters? radios.  The radio system that the 
fire department was using was new to the fire department and had only been operational for a few 
months.  Firefighters reported that they often experienced radio coverage issues, especially in 
commercial buildings and those built with large amounts of concrete and steel.  In response to the 
 21 
individual issues seen at the Southwest Inn fire specifically, ?Bonks? are addressed first.  The 
report states that there were 83 such incidents in the fifteen and a half minutes before the collapse 
and 496 in the first hour of the incident.  Overall, the report states that, ?During the Southwest Inn 
fire there were a total of 761 ?Transmission Bonks? signals on the Southwest Talk Group assigned 
to this incident.? [45].  The next issue that was mentioned was a Digital Delay.  Essentially, when 
a user completes a transmission, there may be a one to one and a half second delay before other 
users hear this traffic.  Therefore, when multiple personnel try to key their radios during this delay, 
the number of ?Bonks? is dramatically increased.  The report next addresses Quick Keys, which 
are a short, and often inadvertent, activation of the PTT button.  While the activation of the button 
is short and no voice message is transmitted, each incident can tie up the Talk Group for three to 
four seconds.  To explain the significance of these activations, the report states, ?During the first 
60 minutes of the Southwest Inn fire, there were approximately 96 ?Quick Keys? which totaled 6 
minutes and 24 seconds of possible usable talk time.  This equates to approximately 11% loss of 
air time in the first hour.  These 96 ?Quick Keys? also led to 111 transmission ?Bonks? which is 
also estimated to be 19% of the total transmission ?Bonks? that occurred at this fire.? [45].  The 
next issue mentioned regarded open and stuck microphones.  To address these issues, the 
department transitioned from a 60 second to only a 30 second maximum message length, with only 
10 seconds if there is no voice or verbal transmission.  Another interesting solution posed by the 
incident reviewers is that of removing a ?stuck? open radio and moving it to another monitored 
channel.  This would prevent other users from switching to a different channel while also clearing 
that same channel.  In addition, the monitoring also means that the radio can be monitored by 
dispatchers rather than the incident command staff.  Finally, discussion was given to if certain 
radios should be given preference over other radios. 
 22 
 In addition to the radio components themselves, the reviewers also examined the system 
linking the radios to the SCBA mounted microphone.  It was determined that one of the reasons 
that the individual radio that activated twenty times was that the wires in this system had been 
damaged by the radiant heat.  The report then states, ?Once the internal hard wires are exposed, 
radio problems such as ?Quick Keys can occur.? [45].  However, the ability to operate a portable 
radio once a firefighter has removed his or her gear was also examined.  The report states that 
Houston firefighters generally wear their radios in their radio pockets on their turnout coats and 
that this SCBA integrated radio system dramatically improves communications.  However, when 
the firefighter?s turnout gear is removed, both the radio and the microphone are integrated into the 
turnout gear.  The report states that when not wearing their turnout gear, ?Most firefighters ?clip? 
the radio to their side using the belt-clip attached to the radio.? [45].  As a response to this issue 
and to assist firefighter communications while the SCBA integrated radio system was being 
repaired, the department would purchase a speaker microphone for all radios.  For short term fixes, 
the report also mentioned that when a radio malfunctioned, the incident commander can call for a 
?radio-man? to fix the radio or to provide replacement equipment.  The report also states, ?During 
the Southwest Inn fire, requests for a ?radio-man? were made six (6) separate times.? [45] 
As a final note, several changes were made to the Houston radio system.   Specifics relating 
to the carrying methods for radios will be discussed in a later subsection. 
1.3.11 2017 Texas Strip Mall Fire 
 The final and most recent incident to be examined is a wind driven fire that occurred in a 
strip mall in Texas [3].  Firefighters arrived and found smoke emitting from the front of the 
building.  The crews entered the building, with the truck company moving to find the fire in front 
of the engine company.  When the fire was found, the truck company firefighters called for the 
 23 
engine company to advance the hose line to their position.  However, one of the truck company 
firefighters then transmitted a MAYDAY message.  Firefighters attempted to rescue this firefighter 
by deploying the rapid intervention team into the building.  However, shortly after the firefighter 
who had initially called the MAYDAY was rescued from the building, one of the rapid intervention 
firefighters was lost.  It was not recognized that this firefighter was lost until he was discovered in 
the building.  When it was recognized that this second rescued firefighter was not the missing 
firefighter from the original truck company who had entered the building, efforts to recover this 
firefighter were initiated.  The firefighter was removed from the building and was pronounced 
dead at the scene. 
 While some of the main factors contributing to the loss of this firefighter was the wind and 
the application of somewhat outdated firefighting tactics, radios partially contributed to the 
confusion on this incident.  The only MAYDAY message or indication that the firefighters were 
missing came from the truck company?s firefighter mentioned above.  However, this firefighter 
experienced his own radio issues.  The report lists six distinct times that his radio is keyed, but two 
of these entries to the timeline mentioned that the radio was keyed multiple times.  A definitive 
timeline is not provided in the report.  This firefighter also possibly inadvertently changed the 
channel on his radio.  This change also could have been made to reach someone on a different 
channel due to the radio traffic at the scene and the firefighter knew that his radio was no longer 
transmitting his voice.  In response to this issue, the report states, ?Radios should be designed and 
positioned to allow the fire fighter to monitor and transmit a clear message.? [3] 
1.3.12 Other Near Miss Incidents 
 While there is a plethora of information available on the incidents above, there are 
numerous more incidents that occur daily.  Some of these have been reported to a website known 
 24 
as firefighternearmiss.com for various reasons.  The first of interest discusses an incident when a 
new firefighter experienced his radio fall from his pocket.  This is a well-known problem with 
radios worn in a radio pocket and is documented in one of the definitive studies shown below.  In 
response to the incident, the self-reporting firefighter stated, ?I had just put the radio in my 
front/chest pocket of my bunker coat when it fell out as I was crawling over the bed. This happened 
in the first 2 minutes of being in the fire.? [41] 
 The second of these incidents occurred when a firefighter?s speaker microphone cord 
became entangled in debris.  The firefighter stated that he was holding his speaker microphone in 
his hand while his radio remained in a radio pocket.  The report states that the cord was entangled 
in a dining room chair, and in the zero visibility, the firefighter was unable to free himself.  Like 
the previous incident, this report goes on to state, ?After a while, the radio actually pulled out of 
my pocket and fell to the floor, and I was able to drag the chair and radio to an area with better 
visibility and get untangled.? [24].  The report concludes stating that if the speaker microphone 
had been secured either to an integral loop sewn to the turnout coat or to the SCBA shoulder strap, 
this entanglement would likely not have occurred. 
 The third incident occurred in 2009 when a firefighter fell from a stairwell.  This fall was 
witnessed by the firefighters working in proximity who attempted to call a MAYDAY for this 
firefighter.  However, this message was not transmitted, so the company officer calling the 
MAYDAY message activated his radio?s emergency button.  Unfortunately, this did not remedy 
the problem, forcing the officer to press the PTT button again.  This action turned off the radio.  
The report states that the department has experienced similar failures, especially when the radio is 
wet.  As a recommendation, the report goes on to state, ?The portable radio manufacturer [name 
deleted] should investigate the issue with the portable radios and create a radio that will hold up in 
 25 
the condition?s firefighters face. Even in routine situations. A radio that turns itself off because of 
minor wetness is unsafe and unacceptable.? [39].  It is also possible that this issue would be 
remedied by carrying the radio in the turnout coat pocket, or under the coat in a radio strap. 
 The final near miss incident of interest occurred only a month after the previous incident 
when two radios failed while the incident commander was transmitting an emergency evacuation 
order [42].  The report states that as the firefighters were moving to combat the fire on the third 
floor after extinguishing the second-floor fire, they were ordered to evacuate.  However, the two 
firefighters operating the hose line stated that they did not hear the evacuation order.  Other 
firefighters behind them began to help remove the hose line from the building and the firefighters 
were luckily able to evacuate.  In response to this incident, the report provides several possible 
recommendations.  The first of these recommendations states that when an emergency evacuation 
order is given, another source of alert must be given, such as sounding the apparatus airhorns.  
Furthermore, the report includes the sentence, ?Everyone should have noticed a lack of 
communications on their radios and left immediately.? [41].  Therefore, while not directly stating 
it, other firefighters operating at the scene appear to have endured radio failures.  While a carrying 
method may not completely prevent an incident of this type from occurring, it would greatly reduce 
the chance of these failures resulting to the heat firefighters endure while operating inside of the 
building. 
1.4 Current Regulatory Standards 
1.4.1 Introduction 
 There are relatively few standards governing fire service portable radios.  Most portable 
radios on the market are designed and built to military specifications.  However, the new National 
 26 
Fire Protection Association (NFPA) 1802 standard sets requirements for fire department 
communications [35].  A discussion of each of these standards is included below. 
1.4.2 NFPA 1802: Standard on Two-Way, Portable RF Voice Communications Devices for Use 
by Emergency Services Personnel in the Hazard Zone  
The 2021 edition of NFPA 1802 contains numerous comments on the design of fire service 
portable radios and the criteria that these radios must be tested to meet [35].  This standard is 
relatively new, with the only edition being published in 2021, one year before the release of this 
document.  For any device, including both portable radios and speaker microphones to be 
compliant with this standard, it must be tested by an independent third party.  Twenty-one samples 
of each device need to be tested for the device to be certified under this standard.  Portable radios 
must pass tests in speech quality, heat and immersion leakage resistance, vibration, impact 
acceleration resistance, corrosion, display surface abrasion, high-temperature functionality, heat 
and flame, product label durability, cable pullout, case integrity, water drainage, tumble ? 
vibration, TIA transmit power, TIA carrier frequency stability, TIA receiver sensitivity, power 
source performance, electronic temperature stress, and antenna VSWR swept frequency.  Speaker 
microphones must also pass many of the tests above.  These tests include speech quality, vibration, 
impact acceleration resistance, corrosion, high-temperature functionality, product label durability, 
cable pullout, case integrity, water drainage, tumble ? vibration, and power source performance.  
However, the standard is written that only ?new? portable radios and speaker microphones are to 
be tested. 
 In the chapter six of the standard, the design standard, there are specific requirements as to 
the service life of the radio, as well as the requirement that the radio must be designed to be 
operated with a gloved hand.  Furthermore, section 6.1.6 states, ?All controls shall be designed to 
 27 
prevent unintentional activation, deactivation, and change of operation.? [35]  Later in this chapter, 
the document states that the timer must be set to one minute, as they were for the Houston Fire 
Department during the Southwest Inn fire.  The standard also states that if the speaker microphone 
fails, the portable radio must make an audible announcement that the device has failed. 
 Regarding internal temperature, the radio must be able to determine and indicate when it 
is over temperature.  This critical temperature is set by the manufacturer and will likely vary 
between different models of radios.  The announcements must be made visually on the device?s 
display as well as audibly once every five minutes until reset by a maintenance technician.  These 
incidents must be logged by the device, and after ten minutes of continuous exposure, the radio 
must audibly indicate that it, or an attached speaker microphone, has been over temperature for a 
longer period. 
 Regarding durability, portable radios and speaker microphones must not melt.  While it 
will be expanded upon in a later chapter of this document, several radios experienced some degree 
of melting so severely that their internal components could be handled through the case. 
 Finally, the document outlines testing requirements.  In the interest of brevity, this 
document will only discuss the quantities of interest to this study, namely temperature.  The 
elevated temperature conditioning procedure states that the device must be exposed to a 
temperature of 71?C, or 160?F for four hours.  The heat immersion test states that the radio must 
be inserted into an oven kept at 22?C, or 72?F at the center of the oven.  The oven will then be 
heated to 177?C, or 350?C for fifteen minutes before being removed and inserted into a 22?C or 
72?F water bath for fifteen minutes.  This cycle is to be repeated six times and the water leakage 
into the power compartment is to be tested.  If this test is passed, then the speech quality is to be 
measured again.  The next test of interest is the high temperature functionality test.  This test 
 28 
requires four replicates to be placed into an oven heated to 260?C, or 500?F with the radios 
mounted, ?as worn?.  The devices are then tested for five minutes with the speech quality measured 
after the device is removed.  Finally, the heat and flame test is discussed.  The device is placed on 
a mannequin over the protective clothing.  The radio is then to be exposed to direct flame 
impingement for ten seconds in the apparatus. 
 It should also be noted that NFPA 1802 speaks on portable radio specifics, but it is not the 
only NFPA standard to speak on radio communications.  NFPA 1221 contains guidance on 
communications center [33].  While these locations can be vital during firefighting operations due 
to their responsibilities during the initial dispatch phase of an incident as well as MAYDAY 
incidents, portable radios are not discussed in this standard.  Rather, the document focuses on the 
design and staffing of these locations. 
1.4.3 MIL-STD-810H 
 This standard is a set of military testing specifications regulating the temperatures that 
equipment must meet to be used by the United States military [6].  There are no provisions for 
portable radios or for firefighters.  This policy was originally published in 1962 but has been 
updated to its current version that was published in 2019.  While this family of standards includes 
guidance on numerous other quantities such as impact and water resistance.  In terms of 
temperature, this standard requires equipment to be heated to 160?F, an equivalent of 71?C. 
 Many of the quantities mentioned in the NFPA 1802 standard were copied from this family 
of military specifications.  This decision was preferable for radio manufacturers as products can 
be dual certified, meaning that a product can be sold both to the fire service as well as to the 
military.  This consideration means that manufacturers can save design, production, certification, 
 29 
and overhead costs by streamlining their product lining while also meeting the demands of the fire 
service. 
 While the NFPA 1802 standard captures a great deal of the quantities of interest in this 
family of specifications, older radios were not designed in accordance with the NFPA 1802 
standard.  Currently, most firefighters worldwide use radios that were not designed in accordance 
with NFPA 1802.  Many manufacturers are still selling portable radios that do not meet the NFPA 
1802 standard to fire departments, meaning that fire departments will likely continue to use non-
compliant radios for several years to come. 
1.5 Fire Department Policies  
 While portable radio carrying methods are largely a personal choice and can vary from 
firefighter to firefighter, some fire departments have issued policies on how firefighters are to wear 
their radios.  While this was centralized to the national capital region, it has spread to several other 
jurisdictions.  However, it should be noted that many fire departments do not have such 
requirements in place. 
 The city of Annapolis, Maryland, provided instruction to wear their radios in a radio strap 
beneath the turnout coat to all their firefighters.  This instruction is despite the inclusion of a radio 
pocket on the issued turnout gear [29].  According to a department member, the policy was 
developed to maintain better accountability of radios.  The officer stated that portable radios were 
not always taken on ?routine? calls such as medical responses.  This development was due to a 
research study conducted by a fire department in the same region.  This study, conducted by the 
Fairfax County (VA) Department of Fire and Rescue will be discussed in detail in a following 
section [38]. 
 30 
 The Anne Arundel County (MD) Fire Department occupies the same county as the 
Annapolis Fire Department and has a similar policy.  However, this policy stops short from 
requiring firefighters to wear their radio in one particular manner.  Firefighters are issued turnout 
gear with sewn in radio pockets as well as radio straps.  The policy simply states that firefighters 
must use gear that meets or exceeds the same standards.  This policy is enforced with personnel 
protective equipment, but not with radios. 
 Firefighters in Montgomery County, Maryland, must wear their radios in a radio pocket.  
Fire Chief?s General Order 11-05 states, ?When firefighter PPE is worn during all firefighting 
operations, the portable radio must be carried inside the sewn-on breast pocket of the turnout coat.?  
[40].  The policy includes a link to the NIST study on this topic and states that the study is the 
reason for this policy.  Originally issued on February 23, 2011, the policy was rescinded on July 
22nd, 2015.  However, after speaking with a member of the department, this policy has yet to be 
replaced and therefore firefighters do follow this guidance [26].  The same firefighter also stated 
that the department issues the firefighters radio straps for responding to medical emergencies and 
other incidents.  
 The city of Ocoee, Florida, maintains a policy that their firefighters must wear their radios 
on department issued radio straps.  A firefighter for the department stated that most of the 
firefighters on the department regularly respond to medical emergencies and find it much easier to 
wear their radios on radio straps anyway.  The firefighter was new to the agency and could not 
provide a justification for the policy. [2] 
 The Pasco County, Florida, Fire Department also requires their firefighters to wear a radio 
strap.  While the department?s policy lists seven other ways to carry their radios, the statement, ?If 
supplied with a commercial radio holsters [sic] [radio strap].? [37]  A firefighter for the agency 
 31 
stated that each of the department radios are equipped with a radio strap, requiring firefighters to 
wear their radios in a radio strap [31].  Finally, regardless of carrying method, the policy also states 
that the lapel microphones should not be removed from the radio. 
 The final fire department that has a radio policy that will be examined in this report is the 
Houston Fire Department.  As mentioned above during the discussion of the Southwest Inn fire, 
the department has endured significant challenges with its radio system.  According to a firefighter 
with the department, there is not a set policy on how firefighters are to wear their radios.  The same 
firefighter mentioned that the department did issue radio straps a few years after the Southwest Inn 
incident, but that the department membership did not find the straps comfortable or practical.  The 
firefighter also stated that the chiefs collected the radio straps and, ?they are probably in some 
garage somewhere.? [30].  However, this firefighter stated that the department has a provision for 
radios within its ?Two Minute Drill.?  This drill, common to the fire service, requires a firefighter 
to be able to don their turnout gear and respiratory protection from his or her station uniform within 
two minutes.  The Houston Fire Department has gone a step further and requires firefighters to 
have their radios turned to the correct channel and on the maximum power setting.  For the 
purposes of this drill, the radio is to be worn in the radio pocket.  The firefighter could not provide 
the department?s justification for this positioning, other than the absence of other equipment to 
carry a radio. 
1.6 Review of Previous Studies 
1.6.1 Introduction 
 This report is far from the first research into this topic.  While most research on firefighter 
radio communications is mainly geared to the portable radio or the system itself, there are a few 
that consider carrying methods.  These will be examined below. 
 32 
1.6.2 NIOSH/Tri-Data Report 
 This report is referenced numerous times in the NIOSH reports that were referenced above.  
This study, the Current Status, Knowledge Gaps, and Research Needs Pertaining to Firefighter 
Radio Communication Systems, is dated as September 2003 and therefore predates numerous 
upgrades in radio technology [36].  However, while the report mainly focuses on the radio systems, 
it does contain information on specific fire departments as well as some behaviors that can affect 
radio communications.  While a carrying method is not one of the behaviors examined in this 
report, the report does mention that having the radio too far or too close to the mouth or mask 
mounted voice amplifier can reduce the quality of a transmission.  It also mentions the difficulties 
of operating a radio while wearing full protective equipment, especially gloves.  The final two 
factors mentioned in this report is potential inadequate training on radio features as well as the fire 
service cultural reluctance to declare a MAYDAY and other emergency traffic. 
 Regarding the specific challenges found by individual fire departments, most of the 
departments mentioned had either recently or were in the process of upgrading to an 800 MHz 
radio system.  None of the fire departments specifically mentioned radio carrying methods. 
1.6.3 NIST TN 1477 
 There are two documents published by NIST relating to firefighting portable radios.  The 
first, titled Testing Firefighting Portable Radios in a Fire Fighting Environment consisted of seven 
radios tested in an apparatus specifically designed for this test [48].  The radios were positioned 
both inside a turnout coat radio pocket and they were left exposed.  No other carrying method, 
including radio straps, were tested.  The radios had their signals analyzed without an antenna.  Only 
the portable radios themselves were tested initially.  Some damage was noted to the antenna when 
tests including it were conducted.  However, these tests did not have their signals examined. 
 33 
 The document first states that the tests were conducted in a Class III thermal environment, 
with a maximum temperature of 260?C and a 10 ??? 2 maximum heat flux.  These thermal ?
classes were defined in Thermal Environment for Electronic Equipment Used by Firefighters, a 
previous NIST study [22].  However, they are summarized in the early stages of this report and 
are shown in Table 1.1 below. 
Table 0.1: Thermal Classes as Reproduced from NIST TN 1474 and NIST TN 1477 
Thermal Class Maximum Time (min) Maximum Temperature (?C) Maximum Flux (kW/m2) 
I 25 100 1 
II 15 160 2 
III 5 260 10 
IV <1 >260 >10 
 
Radios were obtained from three different manufacturers for this study, all of which stated 
that their maximum operating temperature was 60?C, as seen in the military specification 
referenced above. 
 The report also outlines the specialized testing apparatus assembled for this test.  Named 
in the report as the Fire Equipment Evaluator, this device, ?is a closed-loop, recirculating wind 
tunnel designed to simulate thermal conditions up to Thermal Class III.?  The device can produce 
air temperatures up to 300?C and flow velocities from 0.5 ??? to 2.0 
???.  A diagram of the 
apparatus is provided in Figure 1.1. 
 34 
 
Figure 0.1: Fire Equipment Evaluator (FEE) Schematic from NIST TN 1477 
 The radios tested in the simulated turnout coat pocket experienced temperatures inside of 
the pocket on average of 75 ?C lower than the ambient temperatures when the radio was subjected 
to a forced flow of 0.9 ??? and 57 ?C with a 2 
???.  While not stated in the report, it is assumed 
that the ambient temperature was 20?C.  The study found that the radio protected by the turnout 
coat pocket could survive the Class III thermal conditions listed earlier, but the seven of the 
exposed radios all failed at various points during the Class II thermal condition tests.  Three of 
these damaged radios did not return to their normal functioning after returning to the ambient 
temperature.  The results shown as Table 5 in the report are also shown here as Table 1.2. 
 
 
 
 
 35 
Table 0.2: NIST TN 1477 Class III Thermal Soak Results 
Radio Survive Soak Notes 
A No 9.5 min ? no transmit or receive 
A No 8.5 min ? no transmit or receive 
B No Transmission signal shift, increased noise 
B No Transmission signal shift, power loss and increased noise 
C No Transmission signal shift, no transmission on cool down 
C No Transmission signal shift, no transmit or receive on cool down 
 
 This study also examined the speaker microphones designed for each of these radios.  Two 
of the three microphones could not survive a 26?C temperature while the third experienced melting 
and visual deformation while also exhibiting a volume decrease. 
 Included in the conclusions section of the report is the statement, ?Since firefighter turnout 
gear is designed to protect firefighters exposed to Thermal Class III conditions, handheld radios 
should be constructed to handle these conditions.? [22].  The report concludes by stating that the 
?next step? would be for NFPA to develop a standard regarding the thermal environment that 
radios should be designed to meet as this 2006 report far predated the NFPA 1802 standard.  Only 
NFPA 1221 had been published which did not provide these requirements. 
1.6.4 NIST TN 1474 
 The information from the study above was included in the NIST study known as Thermal 
Environment for Electronic Equipment Used by Firefighters which was published just prior to the 
previously presented study [22].  This study mainly examined firefighter Personal Alert Safety 
Systems (PASS), but radios were also examined.  The document outlines the apparatus that is used 
in the 1477 study as well as the thermal classes to which the radios were tested. 
 36 
 An interesting note in this study is the decibel reduction of PASS devices in different 
thermal classes.  As mentioned with one of the speaker microphones in the above study, as 
temperatures increase, the volume tends to decrease.  This result can be attributed to multiple 
effects, but the thermal damage to internal components would be significant.  PASS devices from 
two different manufacturers were tested, and in the Class III thermal environment outlined above, 
decibel reductions from 13 dB to 17 dB were observed.  While a PASS device is simply designed 
to make a distinctive and loud sound, portable radios are designed to transmit intelligible traffic.  
Therefore, while these reductions might be acceptable for PASS devices, reductions of this severity 
in portable radios can be catastrophic to a portable radio. 
1.6.5 Fairfax County (VA) Fire and Rescue Department Study 
 The most recent study examined in this report is one that is published from the Fairfax 
County Fire and Rescue Department in Northern Virginia [38].  In contrast to the NIST study, this 
report did not consider portable radios themselves, but rather it only examined the radio pocket in 
comparison to the radio strap.  While the previously referenced studies focused on the thermal 
environment and the radios themselves, this study focuses more on firefighter specific behaviors.  
This study is also written from the point of view of a single, large fire department.  Therefore, 
manufacturer names are listed in the report and mention is given to department specific equipment 
and locations.  These will be omitted for this report. 
 The Portable Radio Placement in the IDLH [Immediately Dangerous to Life and Health], 
begins by stating that some fire departments, including the authoring agency, issued policies that 
radios can only be worn in the turnout coat pocket.  The document states that this policy was 
written in 2009 while also making mention that Montgomery County, Maryland, has a similar 
policy.  Based on the dates of publication, this policy is the one examined earlier in this report.  
 37 
The study then offers the section, ?Three Critical Reasons why the Radio Pocket is Unsafe.? In 
this section, radio signal degradation, ejection from the radio pocket, and melting of the speaker 
microphone are the three reasons that are listed in this section. 
 The signal degradation of a radio pocket exceeds all other carrying methods according to 
testing conducted with the department?s radio manufacturer?s engineers.  The report states that this 
reduction could be as much as 30 dB, reducing the radio?s power substantially.  As one of the main 
purposes of the Tri-Data report discussed earlier, underpowered radios may be unable to transmit 
through obstructions such as walls [36].  Therefore, with only 0.01 W as the document states, a 
firefighter may have significant difficulties, or even be prevented from, transmitting messages to 
other firefighters on an incident.   The reduction was likely due to the positioning explained earlier 
with the firefighter crawling on ?all-fours.?  The radio strap decibel loss is listed as only 15 dB for 
a crawling firefighter a few pages later.  The report goes on to state that a firefighter can expect to 
experience a 11 dB loss while standing with the radio worn in the radio pocket with only a 7 dB 
loss when worn in a radio strap. 
 Next, the report discusses a portable radio ejection as a reason to not use a radio pocket.  
While these pockets are closed by a hook and loop style closure, this material can melt or be 
degraded with the introduction of water.  These closures also degrade with multiple openings and 
closings.  The report states that due to the weight of the radio, this closure cannot be trusted to 
contain a radio, making it possible that it will be ejected from a pocket.  A radio ejection would 
equate to the exposed radio mentioned above in the NIST 1477 report.   
 The final justification for the shift away from the radio pocket is the melting of the speaker 
microphone cord.  This issue has been mentioned in the critical incidents above, and the report 
 38 
also states that this is the weakest and least protected portion of the radio assembly.  The report 
states that the safest way to wear the shoulder microphone is under the turnout coat. 
 In addition to removing these deficiencies, the report also states that the speaker 
microphone will generally be in approximately the same position as seen with the radio pocket, 
with the added benefit of placing a second PTT button, the one on the portable radio, located near 
waist level.  This is seen as a benefit as it may allow a firefighter to request assistance if he or she 
is entrapped and unable to access the device at his or her chest.  The radio knobs were also 
measured, and it was found that the radio strap moved the critical knobs nearly two feet lower on 
a standing, six foot tall, firefighter. 
 The report also goes further than just stating that the radio strap is the preferred way to 
wear a portable radio.  The report states that the radio strap should be worn under the coat to protect 
the speaker microphone cord with the radio exposed below the coat line.  This consideration is 
made to allow the firefighter to access the knobs and to interact with the radio with only one hand.  
Wearing the radio above the coat line would mean that the firefighter would need to move the coat 
with one hand and interact with his or her portable radio with the other.  The same can be said for 
the radio pocket. 
 Comparing the thermal protection directly, the report states, ?The reality in the NIST report 
is that while the radio pocket provided some level of protection, the pocket is not designed with 
the same thermal protection found on most of the coat. The same level of thermal protection, if not 
more, can be gained when the radio is covered with leather.? [38]  The report also states that when 
a speaker microphone is melted in such a way that a short circuit is created, the radio can be 
?locked? open, prohibiting other firefighters at the scene from broadcasting any radio messages.  
The report states that the best way to prevent an incident of this nature is to wear the cord beneath 
 39 
the coat, rather than being prepared to remove the speaker microphone and using the portable 
radio.  The report states that the Washington D.C. Fire Department was in the process of evaluating 
a sheath to protect the shoulder microphone cord, but that wearing the radio under the coat would 
still be the preferred method.  The report states, ?However, the other issues associated with wearing 
the strap over the coat include: entanglement, less protection than wearing it under the coat, and 
the antenna does not cant away from the body in the same manner as when you wear the radio 
strap under the coat.? [38]. This report also mentions the study conducted by the Prince William 
County (VA) Department of Fire and Rescue in the wake of the Marsh Overlook incident 
mentioned earlier in this report.  The Fairfax study mentions that Prince William?s agency does 
not have a policy on radio strap carrying method, but that firefighters are instructed to wear their 
radios on a radio strap beneath their coat with the radio exposed. 
 As a final note, the report describes a set of training exercises that Fairfax County 
firefighters complete, including an exercise designed to train a firefighter to rapidly evacuate from 
a room that is approaching flashover.  The firefighters must breach a wall and crawl into a second 
room.  However, the report states that multiple recruits experience their radios being caught on the 
wood stud and prohibiting them from exiting the room.  Another exercise trains firefighters to self-
extricate from a wire entanglement.  However, instructors found that when a radio is worn in the 
radio strap, recruits operating in simulated zero visibility conditions could not distinguish between 
the wires and their radio components. 
 As a final note on the discussion of this report, it should be noted that the report itself 
mentions that radio straps of any material were not tested during the NIST evaluation.  It is 
therefore the goal of this study to evaluate the radio strap versus the radio pocket to determine the 
optimal way for firefighters to wear their portable radios. 
 40 
Radio Strap Solutions 
1.7 Introduction 
 Before comparing a specific carrying method, it is important to provide some more 
information on radio straps.  Again, as previously mentioned, radio straps have dramatically 
increased in popularity in the last decade and a half.  With this rise in popularity, there have been 
many updates and advancements in radio straps.  This section will discuss many of these 
advancements and some of the typical ways that different firefighters wear their radios. 
1.8 Radio Strap Carrying Configurations 
 While some fire departments require their firefighters to wear their radios on radio straps 
in specific ways, many firefighters are allowed to wear their radios in their preferred method.  Also, 
even fire departments that require their firefighters to wear their radios on a radio strap may allow 
their firefighters to choose the height and orientation of their radios. 
 One of the main decisions that firefighters must make is the location where they will wear 
their radios.  Some firefighters may choose to leave their radios exposed, as seen in the Fairfax 
study, while others may choose to wear their radios beneath their coats.  Some firefighters may 
choose this location as the radio will be closer to the firefighter?s waist.  This position may be 
preferred when the firefighter is responding to medical emergencies or other incidents when the 
firefighter is not wearing a full complement of protective equipment. 
 Firefighters are also allowed to choose the side where they choose to wear their radios.  
This is generally a personal choice made based on the firefighter?s handedness.  The decision can 
also be made based on the preference when a firefighter is crawling.  Firefighters are often taught 
that in the case of a wire entanglement that they should crawl on their left side.  Therefore, a 
 41 
firefighter may choose to wear his or her radio on the right side so that they are not lying on their 
radios.  However, firefighters who are commonly driving fire apparatus may choose to wear their 
radios on their left so that it does not get tangled with the seatbelt or the radio console inside of the 
apparatus. 
 Another choice that firefighters can make is to wear their radios forward or backward.  
Depending on the radio model, this will change the orientation of the speaker microphone and the 
radio?s graphical display.  However, for one of the most common new models of radio, the display 
is located at the rear of the radio.  Firefighters may also choose to wear their radios ?backwards? 
with the intention of moving the portable radio?s PTT button. 
 As mentioned earlier, choosing to wear the radio strap above or below the coat is also a 
choice that firefighters must make.  For firefighters to wear their radio straps under the coat they 
must put the radio strap on before leaving the station and putting on his or her turnout coat.  
However, firefighters who wear radio straps above their coats can put the radio strap on while 
responding to the emergency or after arriving at the scene.  Some firefighters prefer to wear their 
radios over the coat so that they will have access to the entire radio assembly.  With complete 
access, firefighters will be able to turn their radio to the correct radio channel and be ensured that 
they are monitoring and transmitting on the correct channel.  Other firefighters may choose to wear 
their radios below their coat to provide the speaker mic with the additional protection as mentioned 
in the previous chapter. 
1.9 Commercial Off the Shelf Solutions 
 While firefighters can often decide their preferred locations for their radios, firefighters 
and fire departments have choices when it comes to radio straps.  While there are numerous 
vendors in the industry, a principal difference is the material of the strap.  The main two materials 
 42 
on the market are leather and nylon.  Leather radio straps still hold a large majority of the market, 
but many agencies that are providing all their firefighters with radio straps are choosing to purchase 
nylon radio straps [32] [28]. 
First, for leather straps, there are numerous suppliers.  Both commercially made and 
handcrafted straps are made and in use across the country.  While some fire departments may 
purchase personalized radio straps for their firefighters for fire scene accountability purposes, 
many departments simply purchase the commercially available products due to the lower cost.  
Personalized radio straps are often purchased by individual firefighters.  Also, much of the 
handcrafted market is produced by firefighters themselves.  Leather has been used for various 
pieces of ancillary protective equipment such as glove retaining straps, suspenders, flashlight 
holders, and even helmets.  The reason for the widespread use of leather is both its durability and 
its history.  Many firefighters may work an entire career with the same leather helmet, with some 
even passing it down to their children when they become firefighters.  As leather is also a natural 
material, it chars rather than melts.  Therefore, it has often been perceived as a ?safer? material to 
use for fire protective equipment.  However, leather has been challenged in recent years on two 
key aspects.  Leather radio straps, especially handcrafted ones, are generally heavier than nylon 
straps.  In a quick test conducted with a nylon strap, a commercially produced leather strap, and a 
personalized strap, the nylon strap was the lightest with a mass of 337.3 grams.  The commercially 
produced leather strap followed with a 360.5-gram mass and with the personalized strap finishing 
with a 641-gram mass.  Figures 2.1 shows a comparison of the nylon strap on the left, a handcrafted 
leather strap in the center, and a commercially made strap to the right.   Figures 2.2, 2.3, and 2.4 
show the masses of these three straps as discussed earlier. 
 43 
  
Figure 0.1: Radio Strap Comparison Figure 0.2: Commercially Produced 
Leather Radio Strap Mass 
 
 
 
Figure 0.3: Handcrafted Leather Radio Strap Mass Figure 0.4: Nylon Radio Strap Mass 
 44 
However, while the weight of a radio strap is negligible when compared to the weight of 
other protective equipment, synthetic straps still have one large advantage over their leather 
challengers.  Synthetic radio straps can be decontaminated simply by inserting them into a turnout 
gear extractor.  Because the radio straps are made from fabrics, they can be cleaned with a 
firefighter?s turnout gear.  Leather radio straps can only be cleaned with a manual soap and water 
scrub.  Therefore, as cancer prevention efforts increased in the fire service, nylon radio straps have 
grown increasingly popular.  However, the synthetic radio strap industry is predominantly 
controlled by a few companies.  Yet, the costs for these devices are competitive to their leather 
counterparts.  However, these synthetic straps, often made from nylon or plastic, do melt, rather 
than char.  This possibility has often steered firefighters away from these devices due to the belief 
that the strap will melt when exposed to high heat. 
 While each of the materials has its own benefits, one of the main practical justifications for 
each radio strap is its cost.  While most radio strap vendors will provide discounts to fire 
departments for bulk orders, a single commercially made leather radio strap can be found for 
$50.00 from at least one source.  Handcrafted leather and nylon straps can be found within the 
range of $100 to $150 generally. 
 45 
Computational Fire Dynamics Modeling 
1.10 Introduction to FDS 
 Developed by NIST, Fire Dynamics Simulator, or FDS, is the preemptive fire modeling 
software used by Fire Protection Engineers [23].  These models allow for the evaluation of various 
fire scenarios without spending large sums of money on physical testing.  Parameters such as room 
size, heat release rate, fuel packages, and more can all be altered with a few keystrokes.  A series 
of calculations are conducted at certain time stamps for a particular region of space.  Each of the 
regions constitutes a grid-like arrangement known as a ?mesh.?  In this case, a mesh of 0.1 meters 
was used for each simulation, regardless of the size of the modeled compartment. 
Full-scale testing has already been conducted to verify and validate the veracity of the FDS 
calculations.  Information regarding these validation efforts can be found in the FDS Verification 
Guide.  These calculations are forms of the Navier-Stokes equations and are mainly focused on 
the movement of fluids, especially heat and smoke.  More information on these calculations can 
be found in the FDS Technical Reference Guide [18].  
 In this study, FDS Version 6.7.5 and Smokeview Version 6.7.15 were used.  While not 
mentioned above, Smokeview is the program used to create a graphical representation of the 
modeled environment.  This program is used to show visualizations of the model geometry as well 
as the smoke movement.  Instrumentation used in these simulations included virtual heat flux gages     
placed into the model to determine the heat flux that each radio would receive when worn in a 
certain position.  Assuming a ?worst case? scenario, a firefighter was left approximately five feet 
from the fuel package with the firefighter not entering or exiting the space.  Therefore, the 
firefighter remained in a constant location and was not subject to different flow or temperature 
 46 
gradients.  In addition to the heat flux gage, thermocouples were also placed in the same locations 
to evaluate the temperature that the radios would receive so that the results could be compared to 
the NFPA 1802 and NIST TN 1477 studies.  Finally, it should also be noted that while fire 
modeling is an invaluable tool, emphasis is also placed on the empirical testing of multiple radios.  
These results are presented in the following chapter.   
1.11 Radio Positions   
1.11.1 Pocket versus Strap 
 Multiple firefighters were surveyed to determine a variety of quantities.  Firefighters were 
asked their preferred method to wear their radios so that emphasis could be placed in the 
appropriate areas.  Next, the heights of these radios were measured to determine the location of 
the virtual heat flux and virtual thermocouples in the models.  These heights were taken for a 
standing and for a crawling firefighter.  The positions in which firefighters crawled were also 
evaluated.  These results are listed in Table 3.1.  As a note, the names and fire departments of those 
surveyed were removed. 
 
 
 
 
 
 
Table 0.1:Radio Positioning Survey 
Firefighter Preferred Carrying Method Crawling Position Crawling Standing 
(Strap vs. Pocket) (All 4?s vs. Tripod Height (m) Height (m) 
vs. One Knee) 
 47 
Firefighter 1 Strap with Radio Over Coat Tripod 0.25 0.89 
Firefighter 2 Strap with Radio Under Coat All 4?s 0.51 0.91 
Firefighter 3 Pocket One Knee 0.73 1.30 
Firefighter 4 Strap with Radio Under Coat All 4?s 0.33 0.94 
Firefighter 5 Strap with Radio Under Coat Tripod 0.51 0.86 
Firefighter 6 Strap with Radio Under Coat All 4?s 0.53 0.97 
Firefighter 7 Strap with Radio Over Coat Tripod 0.25 0.97 
Firefighter 8 Pocket All 4?s 0.81 1.04 
 
1.12 Fire Scenarios 
 Four fire scenarios were conducted to best simulate a firefighting environment.  Previous 
experiments conducted measuring the heat release rates of various target fuels were used to choose 
these vital quantities.  Both studies can be found in the University of Maryland?s Burning Item 
Database.  Each of these are summarized below.   
 It is also important to note that these scenarios were not conducted for any of the case 
studies outlined in the previous chapter.  These scenarios were deemed to be specific to the      
incidents.  Also, the specifics of the structure interior, such as the fuel packages and their locations, 
have proven to be indiscernible.  Additionally, several of the incidents such as the 1999 Cherry 
Road [21] and 2007 Marsh Overlook [20] fires have already undergone a thorough FDS analysis.  
Finally, as the focus of this report was not on the compartment fire dynamics that lead to the deaths 
of these firefighters, but rather only to provide a heat flux that a firefighter could expect to 
experience, the FDS simulations were kept as brief as possible. 
1.12.1 Living Room 
 The first simulation that was completed was a fire in a living room.  This small room only 
contained a couch which served as the target fuel.  As this simulation was based on the example 
 48 
file packaged with FDS entitled ?couch,? the heat release rate curve presented below is produced 
from an unedited simulation consisting of the target fuel package without any ventilation as Figure 
3.1.   
800.00
700.00
600.00
500.00
400.00
300.00
200.00
100.00
0.00
0.00 100.00 200.00 300.00 400.00 500.00 600.00
Time (s)
 
Figure 0.1: Couch Example Simulation Heat Release Rate Curve 
A couch was chosen as modern couches are often composed of synthetic materials such as 
polyurethane foam, which often equate to higher heat release rates.  While these more volatile 
fuels have often proved challenging for firefighters, they are quite prevalent in the United States.  
Therefore, because most modern homes contain at least one couch, generally of these synthetic 
materials, a simulation containing a couch was analyzed.  The firefighter was placed so that the 
radios would be 1.6 meters away from the couch when the firefighter was positioned in the tripod 
position, approximately 1.35 meters away when the firefighter preferred to crawl on one knee, and 
approximately 1.1 meters away when the firefighter used the all-fours position.  These positions 
were only in the x-plane, with all the radios being positioned in the same y-plane.  The heights 
presented above were used as the z-plane. 
 49 
Heat Release Rate (kW)
 The room and fuel arrangement can be seen below in Figures 3.2 and 3.3 while Figure 3.4 
shows the overhead view of the compartment.
  
Figure 0.2: Living Room Exterior Corner Figure 0.3: Living Room Door View 
View 
 
Figure 0.4: Dimensioned Living Room Simulation Overhead View
 50 
A single door and window were inserted into the room with the room only containing the 
couch.  No curtains or floor coverings were included, with the walls, ceiling, and floor made of 
gypsum plaster.  While this is a common material found on walls and ceilings, gypsum plaster was 
also used for the flooring material for simplicity.  The simulations were also based on the example 
FDS simulation packaged with FDS entitled ?couch?.  Also, this determination was made as the 
wall material was not of particular interest, and neither was the spread of combustion byproducts.  
Table 3.2 below shows several of the material properties used in this simulation. 
Table 0.2: Living Room Simulation Important Material Properties 
Material Specific Heat Conductivity Heat of Combustion 
??
( ? ) (
?? ) ??
?? ? ? ? ? ? ( ???) 
Fabric 1.0 0.1 20,000 
Foam 1.0 0.05 30,000 
Gypsum Plaster 0.84 0.48 N/A 
 
While many homes may have larger living rooms, a smaller room was chosen as an 
example where conditions would develop more rapidly than in a large room. Also, because the 
main goal of this modeling was to evaluate the conditions a radio would be exposed to a short 
distance from the target fuel, a simulation of a smaller room provides the vital information.   
 Images of the simulation are presented below.  Screenshots were taken of the simulation in 
Smokeview at 30 second intervals, beginning 30 seconds into the simulation.  These are presented 
below as Figures 3.5 through 3.24. 
 51 
  
Figure 0.5: Living Room Simulation 30 Figure 0.6: Living Room Simulation 60 
Seconds Seconds 
  
Figure 0.7: Living Room Simulation 90 Figure 0.8: Living Room Simulation 120 
Seconds Seconds 
  
Figure 0.9: Living Room Simulation 150 Figure 0.10: Living Room Simulation 180 
Seconds Seconds 
 52 
  
Figure 0.11: Living Room Simulation 210 Figure 0.12: Living Room Simulation 240 
Seconds Seconds 
  
Figure 0.13: Living Room Simulation 270 Figure 0.14: Living Room Simulation 300 
Seconds Seconds 
  
Figure 0.15: Living Room Simulation 330 Figure 0.16: Living Room Simulation 360 
Seconds Seconds 
 53 
  
Figure 0.17: Living Room Simulation 390 Figure 0.18: Living Room Simulation 420 
Seconds Seconds 
  
Figure 0.19: Living Room Simulation 450 Figure 0.20: Living Room Simulation 480 
Seconds Seconds 
  
Figure 0.21: Living Room Simulation 510 Figure 0.22: Living Room Simulation 540 
Seconds Seconds 
 54 
  
Figure 0.23: Living Room Simulation 570 Figure 0.24: Living Room Simulation 600 
Seconds Seconds 
Before the radio positions are analyzed, a virtual thermocouple tree was installed in the 
room to track the temperature throughout the space.  In addition, the smoke layer height can also 
be tracked through these devices.  Thermocouples were placed at 0.30-meter increments from the 
floor to the ceiling.  Figure 3.25 shows the temperature versus time curve for all the thermocouples 
in this simulation.  
600
500
400
300
200
100
0
0 100 200 300 400 500 600
Time (s)
Tree_1_T1 Tree_1_T2 Tree_1_T3 Tree_1_T4 Tree_1_T5 Tree_1_T6 Tree_1_T7 Tree_1_T8
 
 55 
Temperature (?C)
Figure 0.25: Living Room Thermocouple Tree Temperature versus Time Curves 
While not labeled in the graph, T1 represents the thermocouple 0.30 meters above the floor, 
T2 measures 0.61 meters above the floor, and so forth. 
From this analysis, the smoke layer depth versus time can be measured.  To determine this 
value from the temperatures obtained from the thermocouple data, some equations will first need 
to be solved.  More information can be found in the referenced Atrium Smoke Control Thesis [1].  
First, the convective portion of the heat release rate is needed.  This value can be found in the FDS 
generated HRR [Heat Release Rate] file as is shown below as ???? .  This quantity can be plugged 
into Equation 1 below to determine the limiting elevation, shown below as ?1.  Figure 3.26 is also 
below showing this calculated quantity. 
2?
? 51 = 0.166????      (1) 
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
0.00 100.00 200.00 300.00 400.00 500.00 600.00
Time (s)
 
Figure 0.26: Living Room Simulation Limiting Elevation 
 With this limiting elevation, the axisymmetric mass flow rate can be calculated using 
Equation 2 below.  While there are two possible equations that can be used to calculate this 
quantity, Equation 2 is presented below as the height to the base of the smoke layer exceeds the 
 56 
Limiting Elevation (m)
limiting elevation for much of the simulation.  However, near the end of the smoke layer descent, 
the limiting elevation exceeds the smoke layer height.  Therefore, Equation 3 is presented below 
to chronicle the mass flow rate after this time.  This point was identified as 164 seconds.  Figure 
3.27 below also shows these variations with time and the equation alteration.   
1? 5
???? = 0.071???
3
? ?
?3 + 0.0018????      (2) 
1?
???? = 0.032 ???
3
? ?      (3) 
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
0.00 100.00 200.00 300.00 400.00 500.00 600.00
Time (s)
 
Figure 0.27: Living Room Plume Mass Flow Rate 
 The final equation that must be solved is to determine the smoke layer temperature.  The 
equation to calculate this value is shown below as Equation 4.  Assuming the ambient temperature 
of 20?C, Figure 3.28 below shows this smoke layer temperature graph. 
????
?? = ? +
?
0      (4) ??????
 57 
Mass Flow Rate (kg/s)
450.00
400.00
350.00
300.00
250.00
200.00
150.00
100.00
50.00
0.00
0.00 100.00 200.00 300.00 400.00 500.00 600.00
Time (s)
 
Figure 0.28: Living Room Smoke Layer Temperature 
With this temperature, the smoke layer interface temperature can now be calculated.  
Equation 5 below calculates for this interface temperature and Figure 3.29 below shows a graph 
of this analysis. 
?? = ??(???? ? ??) + ??    (5) 
Where: 
??= Smoke layer Interface Height  
Temperature (?C) ????= Smoke Layer Temperature (?C) 
??= Smoke Layer Interface Constant (0.85) ??= Lower Layer Temperature (?C) 
 58 
Smoke Layer Temperature (?C)
400.00
350.00
300.00
250.00
200.00
150.00
100.00
50.00
0.00
0.00 100.00 200.00 300.00 400.00 500.00 600.00
Time (s)
 
Figure 0.29: Bedroom Simulation Smoke Layer Interface Temperature 
Finally, the smoke layer height can be calculated.  Because both the smoke layer and the 
measured thermocouple temperatures changed, an effort was made to decrease the sensitivity of 
each individual measurement.  Therefore, to determine the smoke layer height, five consecutive 
thermocouple measurements had to exceed this interface height.  These findings are shown below 
as Figure 3.30. 
3.5
3
2.5
2
1.5
1
0.5
0
0 100 200 300 400 500 600
Time (s)
  
Figure 0.30: Living Room Smoke Layer Height 
 59 
Smoke Layer Height (m)
Smoke Layer Interface 
Temperature (?C)
The final analysis conducted before reaching the heat flux for each individual firefighter is 
the heat release rate of the couch.  While the couch presented at the beginning of this section was 
for the example case without any ventilation, the heat release rate curve presented below as Figure 
3.31 is for the room that was modeled for this analysis.  This graph also shows the heat release rate 
from the example simulation.  The curves report similar curves, but the heat release rate data 
decreases at the end of the curve presented below.  This is likely due to the decreased ventilation 
available in the compartment as it moves closer to flashover.
1000.00
800.00
600.00
400.00
200.00
0.00
0.00 100.00 200.00 300.00 400.00 500.00 600.00
Time (s)
kW Calc_HRR kW Input_HRR
 
Figure 0.31: Living Room Simulation Heat Release Rate Curve 
 The heat flux versus time graphs for each of the firefighters is presented in Figures 3.32 
through 3.34.  Figure 3.27 shows the differences between a crawling and a standing Firefighter 1, 
Figure 3.39 shows the difference between a crawling and a standing Firefighter 2, and so forth.  
Again, the measurements for each of these firefighters can be found above in Table 3.1.  
 60 
Heat Release Rate (kW)
80 100
60
40 50
20
0 0
0 200 400 600 0 200 400 600
Time (s) Times (s)
FF1Crawl FF1Standing FF2Crawl FF2Standing
  
Figure 0.32: Living Room Heat Flux for Figure 0.33: Living Room Heat Flux for 
Firefighter 1 Firefighter 2 
80 80
60 60
40 40
20 20
0 0
0 200 400 600 0 200 400 600
Time (s) Time (s)
FF3Crawl FF3Standing FF4Crawl FF4Standing
  
Figure 0.34: Living Room Heat Flux for Figure 0.35: Living Room Heat Flux for 
Firefighter 3 Firefighter 4 
80 100
60
40 50
20
0 0
0 200 400 600 0 200 400 600
Time (s) Time (s)
FF5Crawl FF5Standing FF6Crawl FF6Standing
  
Figure 0.36: Living Room Heat Flux for Figure 0.37: Living Room Heat Flux for 
Firefighter 5 Firefighter 6 
 61 
Heat Flux (kW/m2) Heat Flux (kW/m2) Heat Flux (kW/m2)
Heat Flux (kW/m2) Heat Flux (kW/m2) Heat Flux (kW/m2)
80 80
60 60
40 40
20 20
0 0
0 200 400 600 0 200 400 600
Time (s) Time (s)
FF7Crawl FF7Standing FF7Crawl FF7Standing
  
Figure 0.38: Living Room Heat Flux for Figure 0.39: Living Room Heat Flux for 
Firefighter 7 Firefighter 8 
Also, to approximate the heat fluxes that would be used for testing, efforts were taken to 
conduct hand calculations using previously determined equations.  While many of these equations 
were designed for pool fires, an analysis was also conducted for both simulations.  Also, because 
the cases are much simpler than the analysis for a solid fuel package, a simplified equation could 
be drawn.  These equations can all be found in both the SFPE Handbook of Fire Protection 
Engineering?s Fifth Edition [16] and in Fire Dynamics?s Second Edition [14].  Both references 
can be found in the References Section of this report for further information.  Starting with an 
empirical equation, Equation 6 was used.  
? +0.5?
      ?"? = 15.4( ? ?)?1.59          (6) 
??
Where:  
?? is the distance from the fire to the source (m) ?? is the pool diameter (m)
Also, before Equation 6, Equation 7 is used to determine the applicability of this test.   
(??+0.5??)0.7 <      (7)
??
Using the firefighters? distances from the couch in the FDS input file as the ?? value, and 
the width of the couch as the ?? value, equation 2 was calculated.  All calculations were found to 
 62 
Heat Flux (kW/m2)
Heat Flux (kW/m2)
be within this suitable range.  From this data, Equation 1 was calculated.  The findings for this 
living room analysis can be found below in Table 3.3.  However, it is important to note that before 
the final heat fluxes can be determined, a safety factor of 2.0 is to be applied [14].  Therefore, the 
final heat fluxes are determined in the farthest right column of the table. 
 
 
 
 
Table 0.3: Living Room Simulation Equation 6 Analysis for Radiative Heat Flux 
Simulation Firefighter Distance to Fire Calculated Heat Calculated Heat Flux with 
(??) (m) Flux (??? 2) Safety Factor (
??? 2) ? ?
Crawling Firefighter 1 1.60 3.6 7.2 
Crawling Firefighter 2 1.10 5.7 11.3 
Crawling Firefighter 3 1.35 4.4 8.9 
Crawling Firefighter 4 1.60 3.6 7.2 
Crawling Firefighter 5 1.35 4.4 8.9 
Crawling Firefighter 6 1.10 5.7 11.3 
Crawling Firefighter 7 1.60 3.6 7.2 
Crawling Firefighter 8 1.10 5.7 11.3 
Standing Firefighters 1.35 4.4 8.9 
 
The standing firefighter heat fluxes would appear to be a bit lower than expected with the 
crawling firefighter?s heat flux would appear to be a bit higher.  This is due to the firefighter?s 
proximity to the burning fuel package.  Firefighters wearing a radio strap were positioned further 
from the fire than those wearing their radios in the turnout gear pocket.  This is also based on the 
 63 
wearer?s preferred method of crawling.  Firefighters who prefer to crawl in a tripod stance will 
have their radios lower to the ground, which is not accounted for in these calculations.   
The next hand calculation analysis that was conducted is the point source radiation model.  
Again, many of the same parameters from Equation 6 above are presented again here, but this 
model does account for the heat release rate of the fuel package.  Therefore, the peak heat release 
rate was used.  The same pool diameter, taken as the width of the couch, was used in this analysis.  
This equation is presented below as Equation 8. 
? ???
?" ???? =
?
2            (8) 4?(??+0.5??)
Where:  
?? is the Radiative Fraction of the Fire ??? is the Peak Heat Release Rate (kW) 
However, as with the previous equation set, Equation 8 cannot be used before calculations 
are conducted for the ?? value.  The calculation provided for this equation is shown below as 
Equation 4. 
?? = 0.21 ? (0.0034??)     (9) 
Using the same pool diameter, the 0.8m couch diameter, the ?? value is found to be 0.207.  
Additionally, the peak heat release rate is calculated through the heat of combustion.  The heat of 
combustion from the input file, multiplied by the density found in the input file, divided by the 
total simulation time, and multiplied by the volume of the couch produced a value of 1568 kW.  
Now, using these values to determine the Equation 8 calculations, Table 3.4 is produced. 
Table 0.4: Living Room Simulation Equation 8 Analysis for Radiative Heat Flux 
Simulation Firefighter Distance to Fire (??) (m) Calculated Heat Flux (????2) 
Crawling Firefighter 1 1.6 6.5 
Crawling Firefighter 2 1.1 11.5 
Crawling Firefighter 3 1.4 8.4 
 64 
Crawling Firefighter 4 1.6 6.5 
Crawling Firefighter 5 1.4 8.4 
Crawling Firefighter 6 1.1 11.5 
Crawling Firefighter 7 1.6 6.5 
Crawling Firefighter 8 1.1 11.5 
 
From this analysis, the standing heat flux is 8.43 ????2  while the average heat flux for 
crawling firefighters is 8.84 ? 0.83 ????2.  Again, these values would appear to be more 
appropriate.  Additionally, because this equation uses a heat release rate in its determinations, it 
should be considered more accurate than the previous equation. 
An analysis was also made of the temperatures received at the radio via the virtual 
thermocouples.  This analysis was undertaken to equate the modeled environment with the NIST 
1477 and NFPA 1802 processes.  As shown with the heat flux versus time graphs above, the 
temperatures were also measured for each firefighter.  Figure 3.40 shows this data for Firefighter 
1, Figure 3.41 for Firefighter 2, and so forth.  Again, it should be noted that these temperatures 
were the air temperatures where the radios would be worn as no protective equipment was 
prescribed for this experiment.  
600 600
400 400
200 200
0 0
0 200 400 600 0 200 400 600
Time (s) Time (s)
FF1Crawl_TC FF1Stand_TC FF1Crawl_TC FF1Stand_TC
  
Figure 0.40: Living Room Temperature Figure 0.41: Living Room Temperature 
versus Time for Firefighter 1 versus Time for Firefighter 1 
 65 
Temperature (?C)
Temperature (?C)
600 600
400 400
200 200
0 0
0 200 400 600 0 200 400 600
Time (s) Time (s)
FF3Crawl_TC FF3Stand_TC FF4Crawl_TC FF4Stand_TC
  
Figure 0.42: Living Room Temperature Figure 0.43: Living Room Temperature 
versus Time for Firefighter 3 versus Time for Firefighter 4 
600 600
400 400
200 200
0 0
0 200 400 600 0 200 400 600
Time (s) Time (s)
FF5Crawl_TC FF5Stand_TC FF5Crawl_TC FF5Stand_TC
   
Figure 0.44: Living Room Temperature Figure 0.45: Living Room Temperature 
versus Time for Firefighter 5 versus Time for Firefighter 6 
600 600
400 400
200 200
0 0
0 200 400 600 0 200 400 600
Time (s) Time (s)
FF7Crawl_TC FF7Stand_TC FF7Crawl_TC FF7Stand_TC
    
Figure 0.46: Living Room Temperature Figure 0.47: Living Room Temperature 
versus Time for Firefighter 7 versus Time for Firefighter 8  
Figures 3.48 and 3.49 below show the temperature comparison between a radio strap and 
radio pocket position.  
 66 
Temperature (?C) Temperature (?C) Temperature (?C)
Temperature (?C) Temperature (?C) Temperature (?C)
 
600 600
400 400
200 200
0 0
0 200 400 600 0 200 400 600
Time (s) Time (s)
Crawling Strap AVG Crawling Pocket AVG Standing Strap AVG Standing Pocket AVG
  
Figure 0.48: Temperatures when Crawling Figure 0.49: Temperatures when Standing 
with a Pocket and with a Strap with a Pocket and with a Strap 
As with the heat flux cases presented above, Figures 3.50 through 3.51 show the 
comparison of the temperature experienced by a firefighter crawling versus a standing firefighter.  
600 600
400 400
200 200
0 0
0 200 400 600 0 200 400 600
Time (s) Time (s)
Crawling Strap AVG Standing Strap AVG Crawling Pocket AVG Standing Pocket AVG
    
Figure 0.50: Crawling and Standing Figure 0.51: Crawling and Standing 
Temperatures with a Strap Temperatures with a Pocket 
For this analysis, it can be noted that the temperatures remained relatively close regardless 
of positioning.  This can be attributed to the lack of thermal insulation.  While radios worn in the 
radio pocket are less protected than those worn under the turnout coat, this was not evaluated in 
this report.  Fire departments often specify and purchase turnout gear through a variety of sources 
 67 
Temperature (?C) Temperature (?C)
Temperature (?C) Temperature (?C)
and in a variety of styles.  Fire departments may have radio pockets sewn in various positions.  
Generally, the radio pocket is only a layer of the turnout coat outer shell, but some fire departments 
do have a layer of insulation as well. 
1.12.2 Bedroom  
The same methodology was conducted as above for a bedroom.  A room with a window 
and a door, as was the case above, was designed with a king-sized mattress.  No other furniture 
or flammable materials were placed in the room.  The King-sized mattress was used again as a 
?worst case? scenario, with a large fuel in the room.  Again, the heat flux and temperature that a 
firefighter could be expected to receive was the focus of this analysis, and therefore the room 
was left to be just large enough to contain the fuel package as well as the firefighter.  The 
mattress used in this simulation comes from the referenced Boras 2004 Swedish National Testing 
and Research Institute test that can be found in the University of Maryland Burning Item 
Database [47], which provided the heat of combustion, which is used to determine the heat 
release rate, and by extension the heat flux.  The heat release rate curve reproduced from this test 
can be found below as Figure 3.52.  
1200.00
1000.00
800.00
600.00
400.00
200.00
0.00
0.00 100.00 200.00 300.00 400.00 500.00 600.00
Time (s)
 
 68 
Heat Release Rate (kW)
Figure 0.52: Reproduced Heat Release Rate Curve with Simulation Heat Release Rate 
While the ventilation arrangement was like the living room simulation, an additional 
window was added.  This window was included to allow for more ventilation, and therefore a 
higher heat release rate.  The inclusion of this additional window was made so that combustion 
across the larger fuel surface would be possible.  Furthermore, a burner was inserted into the 
simulation, rather than a fuel package symbolic of the mattress itself.  This inclusion was made so 
that heat release rate could be maintained at the levels depicted in the test.  Finally, the size of the 
room was changed to accommodate the larger fuel.  Therefore, Figures 3.53 through 3.56 show 
the external arrangement of the compartment, a view through the door, and an overhead view as 
with the living room simulation above.  
    
Figure 0.53: Bedroom Simulation Exterior Figure 0.54: Bedroom Exterior Right Corner 
Left Corner View View 
 69 
  
Figure 0.55: Bedroom Door View 
  
 
Figure 0.56: Dimensioned Bedroom 
Simulation Overhead View 
As with the examples before, the important material properties used in this simulation are 
listed below in Table 3.5. 
Table 0.5: Bedroom Simulation Important Material Properties 
Material Conductivity Heat of Combustion Specific Heat 
(??? ? ?) 
?? ??
( ???) ( ??? ? ?) 
Gypsum Plaster 0.84 0.48 N/A 
 
In addition to the screenshots above, screenshots are included below to show the virtual 
heat and smoke.  These begin with Figure 3.57 below at 30 seconds and continue to Figure 3.76 at 
600 seconds.  These views are shown through the front door, as with the living room simulation 
above. 
 70 
  
Figure 0.57: Bedroom Simulation 30 Seconds Figure 0.58: Bedroom Simulation 60 Seconds 
  
Figure 0.60: Bedroom Simulation 120 
Figure 0.59: Bedroom Simulation 90 Seconds 
Seconds 
  
Figure 0.61: Bedroom Simulation 150 Figure 0.62: Bedroom Simulation 180 
Seconds Seconds 
 71 
  
Figure 0.63: Bedroom Simulation 210 Figure 0.64: Bedroom Simulation 240 
Seconds Seconds 
  
Figure 0.65: Bedroom Simulation 270 Figure 0.66: Bedroom Simulation 300 
Seconds Seconds 
  
Figure 0.67: Bedroom Simulation 330 Figure 0.68: Bedroom Simulation 360 
Seconds Seconds 
 72 
  
Figure 0.69: Bedroom Simulation 390 Figure 0.70: Bedroom Simulation 420 
Seconds Seconds 
  
Figure 0.71: Bedroom Simulation 450 Figure 0.72: Bedroom Simulation 480 
Seconds Seconds 
  
Figure 0.73: Bedroom Simulation 510 Figure 0.74: Bedroom Simulation 540 
Seconds Seconds 
 73 
  
Figure 0.75: Bedroom Simulation 570 Figure 0.76: Bedroom Simulation 600 
Seconds Seconds 
Again, as conducted earlier the thermocouple tree was placed in the room to determine the 
temperatures at various points in the room.  The thermocouples on this virtual thermocouple tree 
were also placed 0.30 meters apart.  Figure 3.77 below shows a graphical representation of each 
of these thermocouples in a temperature versus time curve.  Again, the T1 thermocouple represents 
the temperature 0.30 meters from the ground, T2 represents the temperature 0.61 meters from the 
ground, and so forth.  
450.00
400.00
350.00
300.00
250.00
200.00
150.00
100.00
50.00
0.00
0.00 100.00 200.00 300.00 400.00 500.00 600.00
Time (s)
C Tree_1_T1 C Tree_1_T2 C Tree_1_T3 C Tree_1_T4 C Tree_1_T5 C Tree_1_T6 C Tree_1_T7
 
Figure 0.77: Bedroom FDS Simulation Temperature versus Time Curves 
 74 
Temperature (C)
Also, the smoke layer heights are presented below in Figures 3.82.  Additionally, the same 
figures that were produced for the living room can be found below as Figures 3.78 through 3.82. 
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
0.00 100.00 200.00 300.00 400.00 500.00 600.00
Time (s)
 
Figure 0.78: Bedroom Simulation Limiting Elevation 
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
0.00 100.00 200.00 300.00 400.00 500.00 600.00
Time (s)
 
Figure 0.79: Bedroom Simulation Mass Flow Rate 
 75 
Mass Flow Rate (kg/s) Limiting Elevation (m)
450.00
400.00
350.00
300.00
250.00
200.00
150.00
100.00
50.00
0.00
0.00 100.00 200.00 300.00 400.00 500.00 600.00
Time (s)
 
Figure 0.80: Bedroom Smoke Layer Temperature 
400.00
350.00
300.00
250.00
200.00
150.00
100.00
50.00
0.00
0.00 100.00 200.00 300.00 400.00 500.00 600.00
Time (s)
 
Figure 0.81: Bedroom Smoke Layer Interface Temperature 
 
 76 
Smoke Layer Interface Smoke Layer Temperature (C)
Temperature (C)
3.5
3
2.5
2
1.5
1
0.5
0
0 50 100 150 200 250 300
Time (s)
 
Figure 0.82: Bedroom Simulation Smoke Layer Height from Temperature Data 
The heat flux versus time graphs are also found below for each firefighter.  Again, Figure 
3.83 shows the differences between crawling and standing Firefighter 1, Figure 3.84 shows these 
differences for Firefighter 2, and so forth.  
20.00 30.00
15.00 20.00
10.00
5.00 10.00
0.00 0.00
0.00 200.00 400.00 600.00 0.00 200.00 400.00 600.00
Time (s) Time (s)
FF1Crawl FF1Standing FF2Crawl FF2Standing
  
Figure 0.83: Bedroom Heat Flux versus Time 
Figure 0.84: Bedroom Heat Flux versus Time 
for Firefighter 1 
for Firefighter 2 
 77 
Heat Flux (kW/m)
Smoke Layer Height (m)
Heat Flux (kW/m)
40.00 30.00
30.00 20.00
20.00
10.00 10.00
0.00 0.00
0.00 200.00 400.00 600.00 0.00 200.00 400.00 600.00
Time (s) Time (s)
FF3Crawl FF3Standing FF4Crawl FF4Standing
  
Figure 0.85: Bedroom Heat Flux versus Time Figure 0.86: Bedroom Heat Flux versus Time 
for Firefighter 3 for Firefighter 4 
20.00 20.00
15.00 15.00
10.00 10.00
5.00 5.00
0.00 0.00
0.00 200.00 400.00 600.00 0.00 200.00 400.00 600.00
Time (s) Time (s)
FF5Crawl FF5Standing FF6Crawl FF6Standing
  
Figure 0.87: Bedroom Heat Flux versus Time Figure 0.88: Bedroom Heat Flux versus Time 
for Firefighter 5 for Firefighter 6 
20.00 30.00
15.00 20.00
10.00
5.00 10.00
0.00 0.00
0.00 200.00 400.00 600.00 0.00 200.00 400.00 600.00
Time (s) Time (s)
FF7Crawl FF7Standing FF8Crawl FF8Standing
  
Figure 0.89: Bedroom Heat Flux versus Time Figure 0.90: Bedroom Heat Flux versus Time 
for Firefighter 7 for Firefighter 8 
 78 
Heat Flux (kW/m) Heat Flux (kW/m) Heat Flux (kW/m)
Heat Flux (kW/m) Heat Flux (kW/m) Heat Flux (kW/m)
Again, hand calculations were conducted to approximate these heat fluxes.  The findings 
for the Equation 6 analysis can be found below in Table 3.6.  While the distances to the fire are 
the same, the main difference is the diameter of the mattress.  The narrower portion of the mattress 
was used as this diameter, equating to 1.932 meters.  Therefore, because the diameter is double the 
couch diameter, the heat flux would understandably be double, and a factor of four when the safety 
factor of 2.0 is applied. 
Table 0.6: Bedroom Simulation Equation 6 Analysis for Radiative Heat Flux 
Simulation Firefighter Distance to Fire Calculated Heat Flux Calculated Heat Flux with 
(??) (m) (????2) Safety Factor (
????2) 
Crawling Firefighter 1 1.6 9.8 19.6 
Crawling Firefighter 2 1.1 13.8 27.7 
Crawling Firefighter 3 1.4 11.5 23.1 
Crawling Firefighter 4 1.6 9.8 19.6 
Crawling Firefighter 5 1.4 11.5 23.1 
Crawling Firefighter 6 1.6 13.8 27.7 
Crawling Firefighter 7 1.4 9.8 19.6 
Crawling Firefighter 8 1.1 13.8 27.7 
Standing Firefighters 1.6 11.5 23.1 
As above, the point source radiation model, shown as Equations 8 and 9 earlier were 
conducted as a second way to determine the heat flux, especially with the larger heat fluxes shown 
above.  The same pool diameter, taken as the width of the mattress, was used in this analysis. The 
?? was found to be 0.203 while the heat release rate was determined to be 1900 kW.  This equation 
is presented above as Equation 3 while calculated values are found below in Table 3.7. 
 
 
 
 79 
Table 0.7: Bedroom Simulation Equation 8 Analysis for Radiative Heat Flux 
Simulation Firefighter Distance to Fire (??) (m) Calculated Heat Flux (????2
) 
Crawling Firefighter 1 1.60 7.8 
Crawling Firefighter 2 1.10 13.9 
Crawling Firefighter 3 1.35 10.2 
Crawling Firefighter 4 1.60 7.8 
Crawling Firefighter 5 1.35 10.2 
Crawling Firefighter 6 1.10 13.9 
Crawling Firefighter 7 1.60 7.8 
Crawling Firefighter 8 1.10 13.9 
Standing Firefighters 1.35 10.2 
 
Again, these values would appear to be more appropriate.  Additionally, because this 
equation uses a heat release rate in its determinations, it should be considered more accurate than 
the previous equation. 
 One of the reasons for these much lower modeled heat fluxes is the lower heats of 
??
combustion.  The heat of combustion, measured in ???, is a measure of how much energy is 
released per kilogram of fuel combusted.  Therefore, even though there is more fuel in the 
bedroom, the amount of energy released per kilogram is far lower.  Additionally, the bedroom is a 
larger room.  With the same ventilation openings, there is still more volume in the bedroom for 
the dispersion of the combustion byproducts.      
The same temperature analysis was also determined as above.  First, the temperature values 
for each firefighter are shown below.  Figure 3.91 shows the temperature differences between a 
crawling and a standing Firefighter 1, Figure 3.92 shows these differences for Firefighter 2, and 
so forth.  
 80 
300.00 300.00
200.00 200.00
100.00 100.00
0.00 0.00
0.00 200.00 400.00 600.00 0.00 200.00 400.00 600.00
Time (s) Time (s)
FF1Crawl_TC FF1Stand_TC FF2Crawl_TC FF2Stand_TC
  
Figure 0.91: Bedroom Temperature versus Figure 0.92: Bedroom Temperature versus 
Time for Firefighter 1 Time for Firefighter 2 
400.00 300.00
300.00 200.00
200.00
100.00 100.00
0.00 0.00
0.00 200.00 400.00 600.00 0.00 200.00 400.00 600.00
Time (s) Time (s)
FF3Crawl_TC FF3Stand_TC FF4Crawl_TC FF4Stand_TC
  
Figure 0.93: Bedroom Temperature versus Figure 0.94: Bedroom Temperature versus 
Time for Firefighter 3 Time for Firefighter 4 
300.00 200.00
200.00 150.00
100.00
100.00 50.00
0.00 0.00
0.00 200.00 400.00 600.00 0.00 200.00 400.00 600.00
Time (s) Time (s)
FF5Crawl_TC FF5Stand_TC FF6Crawl_TC FF6Stand_TC
  
Figure 0.95: Bedroom Temperature versus Figure 0.96: Bedroom Temperature versus 
Time for Firefighter 5 Time for Firefighter 6 
 81 
Temperature (C) Temperature (C) Temperature (C)
Temperature (C) Temperature (C) Temperature (C)
200.00 400.00
150.00 300.00
100.00 200.00
50.00 100.00
0.00 0.00
0.00 200.00 400.00 600.00 0.00 200.00 400.00 600.00
Time (s) Time (s)
FF7Crawl_TC FF7Stand_TC FF8Crawl_TC FF8Stand_TC
  
Figure 0.97: Bedroom Temperature versus Figure 0.98: Bedroom Temperature versus 
Time for Firefighter 7 Time for Firefighter 8 
The temperature differences between a crawling radio strap equipped and radio pocket 
equipped firefighter is shown in Figure 3.99 while a standing radio strap equipped, and radio 
pocket equipped firefighter is shown in Figure 3.100.    
200 400
150 300
100 200
50 100
0 0
0.00 200.00 400.00 600.00 0.00 200.00 400.00 600.00
Time (s) Time (s)
Crawling Strap AVG Crawling Pocket AVG Standing Strap AVG Standing Pocket AVG
  
Figure 0.99: Temperatures when Crawling Figure 0.100: Temperatures when Standing 
with a Pocket and with a Strap with a Pocket and with a Strap
Figures 3.101 through 3.102 also show the temperature differences between each 
firefighter depending on their positioning.  
 82 
Temperature (C) Temperature (C)
Temperature (C)
Temperature (C)
300 400
300
200
200
100
100
0 0
0.00 200.00 400.00 600.00 0.00 200.00 400.00 600.00
Time (s) Time (s)
Crawling Strap AVG Standing Strap AVG Crawling Pocket AVG Standing Pocket AVG
  
Figure 0.101: Crawling and Standing Figure 0.102: Crawling and Standing 
Temperatures with a Strap Temperatures with a Pocket 
1.13 Heat Flux Selection 
To select the particular heat flux for the empirical testing efforts, times must be chosen.  
To select these times, emphasis was placed on fire department response times.  While fire 
departments across the United States obviously have different response times, the 2020 edition of 
NFPA 1710: Standard for the Organization and Deployment of Fire Suppression Operations, 
Emergency Medical Operations, and Special Operations to the Public by Career Fire Departments  
provides guidance on fire department response times for career fire departments [34].  The Origin 
and Development portion of the front matter states that the first fire apparatus is to arrive in four 
minutes after leaving the station.  Therefore, with the turnout time of 80 seconds, bringing the total 
time to about five and half minutes.  However, a longer duration was chosen to provide some reflex 
time for both the person alerting the fire department as well as time for the fire department to be 
dispatched and to enter the building.  Therefore, seven minutes and fifteen seconds would be a 
suitable time for firefighters to reach the seat of the fire.  This time provides a heat flux of 
8.23 ????2 for the radio strap and 12.3 
????2 for the radio pocket.  Therefore, 8 
????2 was 
 83 
Temperature (C)
Temperature (C)
selected for the radio strap heat flux and 12 ????2 was used for the radio pocket analysis for the 
bedroom analysis.  When evaluating these heat fluxes for the bedroom simulation, there would 
appear to be agreement.  However, because of the differences between the two compartments, the 
living room values were selected as the reference heat fluxes. 
Therefore, with this data, the empirical testing was conducted using the aforementioned 
heat flux data.  These findings will be discussed in the following chapter.      
  
 84 
Empirical Testing 
1.14 Introduction  
 To assess the behavior of actual radios under simulated real-world conditions, empirical 
testing was conducted.  These tests were completed over multiple days in the Fire Science 
Laboratory at the University of Maryland, College Park.  The following section will outline the 
specific testing methods utilized in this analysis as well as the findings.  Conclusions based on 
these results will be presented in the following and final chapter. 
1.15 Testing Methodology 
1.15.1 Test Set Up 
 First, a frame was constructed to support the turnout coat and radio assembly.  A 2x4 was 
cut to construct a stand before a 0.91-meter-tall vertical portion of the 2x4 was secured to the top 
of the stand.  Two 0.6-meter-long portions of 2x4 lumber were nailed across the stand, to act as 
hips and shoulders.  The entire frame was then wrapped in aluminum foil to reflect the radiant 
energy so that the single frame would be able to withstand all tests.  Additional nails were then 
added to the frame to support the radio strap.   
 After the frame had been constructed, the assembly was then placed on the stand.  For the 
radio strap tests, the radio strap was placed on the stand first, with the radio holster portion of the 
device on the left side of the stand.  This positioning represents a radio being worn on a firefighter?s 
right side.  The turnout coat was then placed on top of the radio strap.  For the radio pocket tests, 
the radio strap was omitted.   
 To instrument the assembly, alterations were needed in the turnout coat.  For the radio 
pocket analysis, incisions were made in the outer shell of the turnout coat so that the thermocouple 
and shoulder microphone wires could be run through the coat.  These wires were held between the 
 85 
layers of the turnout coat and then extended through the neck where it was connected to the data 
acquisition system.  The shoulder microphone was also protected from the thermal environment 
by wrapping the location where the wire connected to the portable radio with a piece of aluminum 
foil to reflect some of the thermal radiant energy directed at the radio.  For the radio strap, no 
incisions were needed as the wires extended above the top of the radio, following the radio strap, 
and extending through the coat at the neck.  Figures 4.1 through 4.3 show the radio pocket setup 
for a variety of angles and Figures 4.4 through 4.6 show the various radio strap assembly. 
  
 
Figure 0.1: Radio Pocket Testing Setup Front  
View 
Figure 0.2: Radio Pocket Setup Top View 
  
 86 
 
 
Figure 0.4: Radio Strap Protected by Coat 
Figure 0.3: Radio Pocket Testing Shoulder 
Microphone Protection 
 
 
Figure 0.6: Exterior Radio Strap Positioning 
Figure 0.5: Radio Strap Beneath Coat 
 
Positioning 
 
 
 
 
 87 
 Each radio battery was instrumented with a Type K thermocouple with a wire diameter of 
0.125 mm.  These thermocouples were used to ensure that the batteries did not overheat.  However, 
the batteries powering these radios were not lithium-ion batteries, but it is expected that future 
developments both in radios and in batteries will result in lithium-ion fire service batteries.  Type 
K thermocouples were also placed at the front of the radio to measure the temperature of the air at 
the front of radio.  Graphs of the data from all these thermocouples will be presented later in this 
chapter. 
 A video camera was also used to film potential radio degradation as well as to serve as an 
audio recording.  This camera was placed in very similar locations for each test.  The camera was 
also used to record the removal of each specimen and the comments made on the conditions of 
each device. 
 While not recorded for this analysis, a Gardon heat flux gauge was used to ensure that the 
radio would be exposed to the desired heat flux.  This gage was held facing a ?warmed up? radiant 
panel and was moved closer until the desired reading was found.   
 LabView was the software used to record the data for each of these simulations.  Two 
thermocouples and the heat flux gauge were all recorded every second, with LabView calculating 
the heat flux from the measured voltage through a user-input equation. 
 Finally, other instruments included a stopwatch to ensure that the tests were kept on track 
while also recording the times of interest.  Testing criteria and the timeline of each test will be 
discussed in the following sub-section. 
1.15.2 Testing Process 
As mentioned above, each day of testing began by determining the positioning of the 
radiant panel in comparison to the testing specimen.  These distances varied depending on the 
 88 
internal conditions of the lab, generally with a 0.1-meter distance to achieve the 12 ????2 heat 
flux and a 0.15-meters distance to achieve the 8 ????2 heat flux.  After these distances had been 
determined, the panel was allowed to cool while the radio was prepared. 
The test specimen was then tested prior to insertion into the assembly.  The radio battery 
was attached to the radio and powered on.  The radio used to communicate with the test specimen 
was also powered on and the transmission and reception abilities of both radios were tested.  The 
test specimen was then inserted into the testing apparatus.  The thermocouple measuring the air 
temperature at the face of the radio was then tested to ensure that it was operating properly before 
being inserted into the holder.  Once the panel had cooled, it was placed at the predetermined 
distance from the test specimen.  A large piece of Kaowool thermal insulation was then placed in 
front of the test specimen to initially shield it from the radiant panel.  The radios were both tested 
a final time, with assurance made that the test specimen had its volume turned to its maximum 
level.  This volume level equates to the highest power that the radio was programmed to transmit.   
Once the camera began filming, the stopwatch started at the same time as the radiant panel 
was plugged in, starting the test.  The heater was allowed to heat for six minutes before the 
temperature data collection was started.  One minute of the pretest conditions were measured 
before the insulation was removed, a total of seven minutes after the test began. 
The test radio then had its shoulder microphone keyed for a period of fifteen seconds before 
the other radio was allowed to transmit.  The operator of this control radio, who was also serving 
as the timekeeper, would state the time to keep all operators informed while also serving to check 
the audio quality of the receiving radio.  It should be noted that both radios remained in the same 
room for the duration of all tests.  This was done to improve visual communication between the 
operators so that a failure could be determined more easily.  It also helped to ensure that operators 
 89 
stayed on the correct schedule as when keyed, the testing radio generally overrode the control 
radio.  The control radio could also override the testing radio, meaning whichever radio was keyed 
first would have transmitting priority.   
The radio pocket tests were all allowed to progress until the radio failed.  There was no 
time limit for these tests.  The radio strap tests were conducted with the target of a thirty-minute 
exposure.  If the radio was still transmitting and receiving adequately, then the specimen was 
deemed to have passed the test and the test concluded.  To conclude these tests, the insulation was 
placed in its initial position while the heater was also removed. 
The radios were allowed to cool for a minimum of five minutes before they were removed 
from the apparatus.  The condition of each radio case was also evaluated during this period.  The 
test battery was removed from the radio and allowed to cool while the radio was disassembled.  In 
the case of a failure, the individual components were also tested.  The antenna and battery were 
placed on a radio known to function and new antennas and batteries were placed on the tested radio 
after it had cooled.  If the radio could successfully pass this final test, then the radio was used in a 
subsequent test. 
1.15.3 Test Matrix 
 Below are four test matrices, one for each series of tests.  In total, 20 tests were conducted 
using twelve different radios. The findings from radios that were tested multiple times can be found 
near the end of the testing results section which follows this subsection.  The first matrices describe 
the radio pocket tests and can be found below as Table 4.1.  These tests were also the first ones 
conducted.  Series-specific information can also be found in the Radio Pocket Testing subsection 
of the following section.  Next, the 8 ??? 2 radio strap simulations are shown in Table 4.2 as ?
these were the second series of tests conducted.  These tests were repeated at the higher 12 ????2 
 90 
heat flux in the third matrix, shown in Table 4.3.  The final two tests are shown in Table 4.4 as the 
two tests conducted in a radio strap on the exterior of the turnout gear. 
Table 0.1: 12 ????2 Radio Pocket Test Matrix 
Test Number Radio Model Used Radio Exposure Number 
Pocket Test #1 Radio A.1 1st Exposure 
Pocket Test #2 Radio B 1st Exposure 
Pocket Test #3 Radio A 1st Exposure 
Pocket Test #4 Radio A.3 1st Exposure 
Pocket Test #5 Radio C.1 1st Exposure 
Pocket Test #6 Radio A.1 2nd Exposure 
Table 0.2: 8 ????2 Radio Strap Test Matrix 
Test Number Radio Model Used Radio Exposure Number 
8 Strap Test #1 Radio A.4 2nd Exposure 
8 Strap Test #2 Radio A.3 2nd Exposure 
8 Strap Test #3 Radio A.4 3rd Exposure 
8 Strap Test #4 Radio C.2 1st Exposure 
8 Strap Test #5 Radio C.3 1st Exposure 
8 Strap Test #6 Radio A.3 3rd Exposure 
Table 0.3: 12 ????2 Radio Strap Test Matrix 
Test Number Radio Model Used Radio Exposure Number 
12 Strap Test #1 Radio A.4 4th Exposure 
12 Strap Test #2 Radio C.4 1st Exposure 
12 Strap Test #3 Radio C.3 2nd Exposure 
12 Strap Test #4 Radio A.3 4th Exposure 
12 Strap Test #5 Radio A.4 5th Exposure 
12 Strap Test #6 Radio C.4 2nd Exposure 
 
 
 91 
Table 0.4: Exterior Radio Strap Test Matrix 
Test Number Exposure Heat Flux (??? ) Radio Model Radio Exposure Number ?2
8 Strap Outside #1 8 Radio C.5 1st Exposure 
12 Strap Outside #1 12 Radio C.6 1st Exposure 
 
1.16 Testing Results 
 Six replicates each of the radio pocket and under coat radio strap tests were conducted.  A 
single replicate of each external radio strap test was conducted.  Each section below contains both 
a thermal analysis of each test as well as an overview table.  These tables state the pass or fail 
status of each test and any notes taken during the evaluations.  In the case of a failure, the time that 
the signals degraded and the time that the radio was deemed a failure is also shown.  The signal 
degradation took many forms, with some manifesting as dramatically increased audio feedback, 
significantly decreased volume, or the inability to transmit. 
1.16.1 Radio Pocket Testing 
 The first set of tests completed were the radio pocket tests.  These tests were conducted 
first to coordinate the findings with those of the previous NIST TN 1477 study.  In addition, these 
tests served as a benchmark to the following tests.  It was determined that if a future test could 
surpass the duration of the longest radio pocket test, then the radio was better protected from using 
the alternate carrying method.  Another reason for this selection was the heat flux used for these 
tests.  As discussed in the previous chapter, the heat flux for these tests was approximately 
12 ????2. 
 Many of these radios had quite similar failure times, excluding the first radio.  This radio 
was tested without a shoulder microphone, using a bungee cord assembly to relieve pressure from 
the radio?s PTT button.  Images of the setup of this radio can be seen as Figure 4.7.   
 92 
 
Figure 0.7: Radio Pocket R1 Setup Image 
It was noted during this test that this assembly would not be feasible, as the radio moved 
toward the heater, increasing the heat flux.  However, this test remained part of the test series as it 
did partially account for some heat flux variations.  As mentioned previously in this report, 
firefighters would likely be moving while working inside of the structure, producing a varying 
heat flux.  These variations would also be caused by the fire itself not emitting a perfect, constant 
heat flux.  Because the heat flux gage was not placed next to the radio during the testing, the heat 
flux variation was not measured in the testing.  However, an analysis was conducted to determine 
this variation. 
Assuming the radio moved 0.01 meters closer to the radiant panel, the previous hand 
calculations were used.  Using Equation 5, an analysis was first conducted to determine the ?? 
value.  This analysis was conducted using the fixed 12 ????2 heat flux and the 0.1 m distance.  
 93 
This ?? value was calculated as 0.15 m, and when inserted into Equation 5, the altered heat flux 
was determined to be 13.50 ??? . ?2
This test is included in the temperature analysis below as well as in the failure analysis.  
However, it was removed from the calculations of the average temperature and time to failure 
calculation presented at the end of this subsection.  The temperature graph for Radio Pocket Test 
1 is shown as Figure 4.8. 
200
180
160
140
120
100
80
60
40
20
0
0 2 4 6 8 10 12 14 16
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.8: Radio Pocket Test #1 Temperature Data 
 The radio used during this first test did not sustain any discernable visual damage.  Before 
and after pictures of this radio are shown as Figure 4.9 and 4.10.  However, there was some slight 
discoloration to the radio?s antenna.  Pictures can be seen as Figures 4.11 and 4.12.  However, it 
should be noted that the radio, battery, and antenna were able to transmit separately after this test.  
The antenna was not used for any future tests, but the radio and battery were used for subsequent 
tests.   
 94 
Temperature (?C)
  
Figure 0.9: Radio A.1 Pre-Test Figure 0.10: Radio A.1 Post Pocket Test R1 
  
 
 
Figure 0.12: Radio A.1 Antenna Post Pocket 
Figure 0.11: Radio A.1 Antenna Post 
Test R1 Close Up 
Pocket Test R1 
The first radio also did not provide any significant degradation, possibly in response to the 
short duration of the test.  However, this should serve as a concern for firefighters as a user would 
not have advanced warning that his or her radio was on the verge of failure.  Also, in the absence 
of a set schedule of messages, it could possibly be impossible for a firefighter to know that his or 
 95 
her radio had already failed.  Therefore, as in the Riverdale Heights incident discussed earlier, the 
trapped firefighter would likely have no idea that a MAYDAY message was not being received.  
 The second test also served as a bit of an outlier as it was the longest test of any carrying 
arrangement that resulted in a failure.  This radio was a more modernized radio than the others and 
used its own battery.  The same style antenna was used for all radios.  This radio experienced 
significant signal degradation about halfway through the test, but it was able to continue the test.  
The radio was unable to transmit after the test was completed.  The radio and antenna both showed 
extensive damage.  The radio had to be removed from the radio pocket with a knife as the rubber 
sheathing on the antenna melted during the test and coated much of the speaker of the battery.  The 
rubberized channel selector and power knobs also showed significant damage, with the channel 
selector knob being left inoperable.  A pair of pliers was used to power up the radio, but the radio 
remained unable to transmit after the test.  Furthermore, the radio produced a chirp when powered 
up before the test, but this was absent after the test.  Coupled with the extreme screen damage, it 
was not possible to determine if the radio could be powered on.  Figures 4.13 through 4.17 show 
this damage. 
  
 96 
 
Figure 0.13: Radio B Damage Before 
 
Removal 
Figure 0.14: Radio B Antenna and Knob 
Melting 
 
Figure 0.15: Radio B Close Up Damage Prior 
 
to Removal 
Figure 0.16: Radio B Damage After Removal 
 97 
 
Figure 0.17: Radio B Damage Close Up After Removal 
The temperature data for this second radio is very similar to the other radios tested, only 
this radio survived for a longer duration.  The comparison can be seen at the end of this subsection, 
but the radio did not increase in temperature at the same rate as the other radios.  This could be the 
reason that the radio lasted for a longer duration.  A graph of this radio?s face temperature and the 
temperature at the battery can be seen below as Figure 4.18. 
 98 
300
250
200
150
100
50
0
0 5 10 15 20 25 30 35 40
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.18: Radio Pocket Test #2 Temperature Data 
 The third radio to be tested provided results which were consistent with the rest of the 
pocket radio tests.  Note, this radio also did show some significant static about ten minutes into its 
exposure, but it was still able to transmit and receive.  However, it did suffer the significant signal 
loss just over twenty minutes into the test, as depicted in Table 4.5.  The radio also suffered 
significant visual damage.  The screen was significantly crazed and unreadable.  The top of the 
case also suffered melting and shape deformation, allowing some of the radio?s internal 
components to be visible.  Figures 4.19 through 4.21 show this damage.  However, the radio and 
its battery continued to function with a new antenna.  Both devices were used in subsequent testing. 
 99 
Temperature (?C)
 
Figure 0.19: Radio C Damage After Pocket Test R3 
  
 100 
  
Figure 0.20: Radio C Melting After Pocket Figure 0.21: Radio C Screen Crazing After 
Test R3 Pocket Test R3 
This radio also behaved like the other radios thermally.  The temperature recorded at the 
battery followed the same slope as many of the other tests.  The face temperature on this radio also 
largely followed those of the other radios tested in the pocket.  Figure 4.22 shows the battery and 
face temperatures of this third radio. 
 101 
250
200
150
100
50
0
0 5 10 15 20 25 30 35
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.22: Radio Pocket Test #3 Temperature Data 
 The fourth radio again behaved like the other radios tested in the radio pocket.  However, 
this radio was the first radio that demonstrated a ?bonk.? The cause of this failure was unknown, 
but the radio was able to transmit for the remainder of the test, resulting in the radio?s failure.  The 
radio also experienced a dramatic increase in feedback at seven minutes and forty-five seconds of 
exposure to the radiant panel.  However, the radio remained able to transmit.  This radio also did 
not experience a significant amount of visual damage. 
 The fourth radio did follow the same trend as the other radios in terms of temperature at 
the battery, but its face temperature was very erratic during the early stages of the test.  The general 
trend of the temperature increase was visible, but there were instantaneous temperatures that 
proved to be quite high.  A potential explanation for these spikes could be that the thermocouple 
moved and contacted the outer surface of the turnout gear, rather than measuring the air 
temperature between the radio and the pocket?s outer edge.  This theory is supported by the damage 
 102 
Temperature (?C)
shown to the radio pocket after the tests.  Images and discussion of the turnout gear?s performance 
can be found at the end of this chapter and a graph of this radio?s temperature can be found in 
Figure 4.23. 
250
200
150
100
50
0
0 5 10 15 20 25
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.23: Radio Pocket Test #4 Temperature Data 
 The fifth radio to be tested in the turnout coat pocket showed the fastest time to failure 
other than the first test.  This radio experienced severe visual damage with the face thermocouple 
melted to the face of the radio.  The antenna was visually bent and internal components of the radio 
were visible.  The screen could not be read, and the radio again had to be cut from the turnout coat 
as the coat was fused to the radio due to the melted rubber sheathing.  This radio and its antenna 
were unable to be used for any further testing.  The radio?s battery was usable for future testing 
after it had cooled.  Figures 4.24 through 4.28 show the extensive thermal damage experienced by 
radio C.1. 
  
 103 
Temperature (?C)
  
 
Figure 0.25: Radio C.1 Top View after 
 Figure 0.24: Radio C.1 Damage After 
Pocket Test #5 Prior to Removal
Pocket Test #5 Prior to Removal 
  
Figure 0.26: Radio C.1 and Thermocouple Damage After Removal After Pocket Test #5
 104 
  
Figure 0.27: Radio C.1 and Antenna Figure 0.28: Radio C.1 Damage Close Up 
Damage After Removal After Pocket Test After Pocket Test #5 
#5 
While the fifth radio lasted significantly longer than the first radio, it fared similarly 
regarding the lack of advanced warning.  The radio did not experience a dramatic increase in 
feedback or reduction in volume.  Also, no ?bonk? was heard from this radio. 
 Regarding temperature, the fifth radio did experience a higher temperature at the battery 
than the other radios that were tested.  The face temperature also followed an erratic shape, likely 
due to the fusion of the thermocouple insulation with the face of the radio.  This thermocouple 
likely contacted the face of the radio rather than measuring the air temperature that the radio was 
 105 
exposed to inside of the pocket.  However, the general trend of an increase in temperature was 
observed.  Figure 4.29 shows the temperature data for this fifth test. 
250
200
150
100
50
0
0 5 10 15 20
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.29: Radio Pocket Test #5 Temperature Data 
 The final pocket test conducted was the sixth test.  The radio used for this analysis was the 
first radio used in the pocket testing.  However, this radio lasted significantly longer during this 
final pocket test yet experienced significant thermal damage.  The antenna?s rubber sheathing 
melted significantly onto the face of the radio, again requiring the radio to be cut from the turnout 
coat pocket.  The face temperature thermocouple also melted to the face of the radio, possibly 
explaining the erratic face temperature behavior.  The radio casing itself also melted near the top 
of the radio, leaving plastic melted to the screen.  Internal components of the radio were also visible 
at the conclusion of this test.  At a cursory glance, this radio experienced more visual thermal 
damage than any other radio tested.  Figures 4.30 through 4.35 attest to this extreme damage. 
 106 
Temperature (?C)
  
Figure 0.30: Radio A.1 Damage Prior to Figure 0.31: Radio A.1 Damage Post 
Removal After Pocket Test #6 Removal After Pocket Test #6 
  
Figure 0.32: Radio A.1 Damage Post Figure 0.33: Radio A.1 Damage Close Up 
Removal After Pocket Test #6 After Pocket Test #6 
 107 
  
Figure 0.34: Radio A.1 Top Damage After Figure 0.35: Radio A.1 Knob and Antenna 
Pocket Test #6 Melting After Pocket Test #6 
Thermally, the sixth test largely followed the same trends outlined by the prior tests.  This 
radio experienced the highest temperature measured at the battery, with a few points over 300?C.  
The face temperature did experience some variation as discussed in the prior paragraph, but this 
was far less than some of the other radios.  The temperature at the battery also experienced some 
variation, with the figure below suggesting that there were two sets of battery measurements.  
These measurements would likely be due to the air movement through the radio.  With the radio 
suffering the extreme thermal damage shown in the figures above and the failed radio pocket 
closure integrity, heated air was able to travel through the case and into the radio itself.  Figure 
4.36 below shows the graph of the temperature data of this sixth and final pocket test.
 108 
350
300
250
200
150
100
50
0
0 5 10 15 20 25
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.36: Radio Pocket Test #6 Temperature Data 
 With all the pocket tests completed, an analysis of all the radios tested in the pocket was 
conducted.  As previously mentioned, the main measured metric of these tests was the duration of 
the testing with the failure criteria for all tests were two consecutive unsuccessful transmissions.  
Again, these periods were fifteen seconds each.  First, Table 4.5 is presented to show both the 
failure time and the failure temperature measured at the battery of each of these radios.  From this 
table, Figure 4.37 is generated to serve as a graphical depiction of the time to failure as well as the 
temperature at the battery when these radios failed.  This figure is presented to show the proximity 
of both the times and temperatures at which the radio failed.  It should be noted that all radios 
testing during this analysis, except for the second radio tested during the pocket tests, were from 
the same manufacturer and were the same style radio. 
 
 
 109 
Temperature (?C)
Table 0.5: Radio Pocket Failure Time and Temperatures 
Test Radio Failure Failure Time to Signal Total Test Failure Mode 
Time (s) Temperature at Degradation (s)  Duration (s) 
Battery (?C) 
Pocket A.1 224 178.7 N/A 570 Transmission 
Test R1 Failure  
Pocket B 1815 228.0 525 2168 Transmission 
Test R2 Failure  
Pocket A.2 1503 225.4 600 1854 Transmission 
Test R3 Failure  
Pocket A.3 1101 197.2 465 1422 Transmission 
Test R4 Failure  
Pocket C.1 755 225.2 N/A 1117 Transmission 
Test R5 Failure  
Pocket A.1 1082 276.8 N/A 1425 Transmission 
Test R6 Failure  
 
290
Radio 6
270
250
230
Radio 5 Radio 3 Radio 2
210
Radio 4
190
Radio 1
170
150
0 5 10 15 20 25 30 35
Time (min)
 
Figure 0.37: Radio Pocket Failure Time and Temperature  
 110 
Failure Temperature (?C)
Next, the cumulative temperatures at the battery and at the face of each radio are 
presented below as Figures 4.38 and 4.39 respectively. 
350
300
250
200
150
100
50
0
0 5 10 15 20 25 30 35 40
Time (min)
Battery Temp 1 (?C) Battery Temp 2 (?C) Battery Temp 3 (?C)
Battery Temp 4 (?C) Battery Temp 5 (?C) Battery Temp 6 (?C)
  
Figure 0.38: Radio Pocket Test Temperature at Battery 
250
200
150
100
50
0
0 5 10 15 20 25 30 35 40
Time (min)
Face Temp 1 (?C) Face Temp 2 (?C) Face Temp 3 (?C)
Face Temp 4 (?C) Face Temp 5 (?C) Face Temp 6 (?C)
  
Figure 0.39: Radio Pocket Test Face Temperatures  
 111 
Temperature (?C) Temperature (?C)
Additionally, it was desired to note specifically what components in the radio failed.  Of 
the twenty total tests, thirteen of radios failed throughout all four test series.  However, some of 
these radios returned to their normal functions at the conclusions of the tests and the cool down 
period.  Therefore, because only four radios did not return to their normal function after the 
conclusion of the tests, it was deemed impossible to determine the specific compoents that led to 
each radio?s failure.  Additional comments will be made about the ?bonk? failures that occurred 
in the following series.   Finally, it is believed that the time to failure of each radio and the radio 
temperature are in relation to each other.  In an effort to determine this relationship, the area 
under the time temperature curve was determined.  The results of this analysis are shown below 
in Table 4.6. 
Table 0.6: Total Average Pocket Time vs. Tempearture Data 
Radio Duration of Exposure (s) Area Under the Battery Failure Time-Temperature Curve 
(? ? s) 
Radio 1 224 61,950 
Radio 2 1815 377,600 
Radio 3 1503 342,600 
Radio 4 1101 219,800 
Radio 5 755 183,800 
Radio 6 1082 323,700 
 
 These areas provide a relatively small margin of error, with the average of these values 
equalling 251,592 ? 48,627 ? ? s.  However, an effort was made to reduce this standard error by 
removing the first radio from this analysis.  For Radios 2 through 6, the average value increases to 
289,522 ? 37,270 ? ? s.  While this analysis removes the first radio, this average provides a 
smaller standard error.  Coupled with the substiantial time difference, this smaller error would 
 112 
apear to better account for the radio failures.  Additionally, the precision of these values would 
seem to confirm the suspicion that radio failures are driven based on tempearture at the radio 
battery.  This observation will be discussed in the Conclusions chapter of this report. 
While many of these trends were discussed above, Figures 4.38 and 4.39 show all of the 
temperature data for the radios worn in the turnout coat pocket.  While the failure times may be 
quite different, there are a few possible explanations that can be made.  The first is the radios 
themselves.  All Radios with an A prefix had a keypad, meaning that numerical entries could be 
made on the radio.  While firefighters rarely use these functions, many radios remain equiped with 
these buttons.  However, while the functionality is increased in these radios, the apertures allow 
for more heated air to enter the radio and to increase the internal temperature.  Because the radios 
have the same size vents located at the rear of the radio facing the battery, this heat is dispated at 
the same rate in both A and C model radios.  Therefore, Radio A models were more succeptable 
to thermal soak damage.  Figures of these two different models can be seen below in Figure 4.40. 
 
Figure 0.40: Radio Model A (L) and C (R). 
 113 
Another potential explanation for the failure time discrepancies are the dates of 
manufacture.  Radio A models were the oldest radios tested.  During the period where model A 
radios were most common, the radio industry was on the precipice of  digital technology [36].  
Therefore, as many fire departments and public safety agencies updgraded to digital 800 MHz 
frequencies, the portable radios were upgraded.  Because of the increased cost of these newer 
radios, upgrading the older radios was much more cost effective.  Therefore, some of the Radio A 
models that were obtained from agencies that had previously conducted these upgrades may have 
been able to transmit both in a digital and analog modes.   This consideration would also explain 
why Radio A models did not endure the ?bonk? failures that Radio C models did.  Again, more 
information will be provided on these failures in the following subsections of this report. 
While all of these radios, other than the first, would exceed the classifications outlined in 
the NIST TN 1477 study, many of the radios experienced significant degradation during this 
period.  It is important to note that both the receiving radio and the transmitting radio were located 
in the same laboratry space, with the radios never being more than thirty feet away from each 
other.  While this distance may seem large enough to communicate through a typical home in the 
United States, it would almost certainly be exceeded by a commercial or a multi-family structure.  
The same radios might even experience significant challenges transmitting to firefighters even in 
other rooms as typical buildings would have partitians such as walls.  While these radios might 
still be able to transmit through a typical gypsum and plywood wall, they might not be able to 
communicate through walls constructed of concrete and steel.  More information about 
transmitting through walls can be found in the NIOSH/Tri-Data report discussed in the first chapter 
of this report [36]. 
 114 
These tests show agreement with the NIST TN 1477 study and would seem to indiciate 
that the radio pocket is a viable way to carry a portable radio, in terms of thermal performance. 
1.16.2 8 ????2 Radio Strap Testing 
 The second test battery conducted were the radio strap tests at a 8 ????2 heat flux.  These 
tests were conducted at this heat flux in alignment with the fire modeling described in the previous 
chapter.  Unlike the tests described in the previous section, a time limit was placed for these tests.  
Each test was given the same seven-minute warm-up time, a maximum of thirty minutes of 
exposure, and a minimum of a five-minute cool down period.  This period was also chosen as it 
exceeded the radio pocket test with the longest duration of 2,168 seconds.  If the radio survived 
this entire period, then it was deemed to have successfully survived the test.   
 The temperature data from the first test is presented below as Figure 4.41.  This curve 
shows a similar shape as the pocket tests, with much lower temperatures.  The radio used for this 
test had already been exposed during the pocket tests, but no visual damage was seen in this test 
for the radio.  However, the radio strap itself did suffer from some melting with the label and some 
of the loop portion of the hook and loop closure melted.  The hook portion of the closure also 
became more brittle as its nylon backing was repeatedly exposed to the thermal insult.  It should 
be noted that these two portions of the assembly were the only two portions exposed during the 
test.  The upper portions of the radio, including the knobs, screen, and antenna were all protected 
by the turnout coat.  One case was tested after the conclusion of these tests with the entire radio 
strap assembly exposed. 
 115 
160
140
120
100
80
60
40
20
0
0 5 10 15 20 25 30 35 40
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.41: 8 ????2 Radio Strap Test #1 Temperature Data 
 Like the first test, the second test did not experience a failure or any discernable signal 
degradation.  There also was not any visually discernable damage to this radio.  The temperature 
data from this test are shown below in Figure 4.42. 
 116 
Temperature (?C)
140
120
100
80
60
40
20
0
0 5 10 15 20 25 30 35 40
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.42: 8 ????2 Radio Strap Test #2 Temperature Data 
As mentioned previously, the third radio did experience a failure.  This radio was deemed 
a failure after it suffered a ?bonk? or a busy signal.  Attempts were made to key the radio several 
times, but they all proved to be unsuccessful.  The control radio was always able to transmit, 
despite this busy signal.  The control radio was also powered off so that the test radio could be 
activated without any other radio on the same frequency, but this did not remedy the problem.  
However, the radio was keyed after about twenty seconds of the ?bonk.?  The same message 
schedule was then used, and the control radio was keyed on schedule.  After this control radio 
message, the test radio was able to transmit for another fifteen seconds.  However, after that 
message from the control radio, the test radio encountered another ?bonk.? This cycle continued 
four times until the radio was deemed a failure when the ?bonk? could not be overcome.  The 
temperature data for this radio is found below as Figure 4.43.  
 117 
Temperature (?C)
160
140
120
100
80
60
40
20
0
0 5 10 15 20 25 30 35 40
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.43: 8 ????2 Radio Strap Test #3 Temperature Data 
 The fourth test proceeded in the same manner as the first two tests in that this test did not 
fail.  As with the first two tests, a radio from the pocket tests was used rather than an untested radio 
like in the third test.  The temperature data followed a relatively smooth curve and can be seen 
below in Figure 4.44. 
 118 
Temperature (?C)
250
200
150
100
50
0
0 5 10 15 20 25 30 35 40
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.44: 8 ????2 Radio Strap Test #4 Temperature Data 
The fifth test suffered the same fate as the third test, albeit at a lower exposure time.  This 
test also was conducted on a radio of the same model and sourced from the same vendor as the 
third test.  However, as with the third test, there was no discernable visual damage to the radio.  
This radio produced its first ?bonk? in just under eighteen minutes of exposure time.  This signal 
was overcome four times before the ?bonk? could not be overcome in a thirty second period, 
identical to the third test.  The same efforts were taken by turning off the control radio so that the 
only radio that was transmitting was the tested radio, but this effort was unable to overcome the 
transmission failure.  The temperatures for this radio also followed a similar curve as the other 
tests and is shown below as Figure 4.45. 
 119 
Temperature (?C)
160
140
120
100
80
60
40
20
0
0 3 6 9 12 15 18 21 24 27
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.45: 8 ??? 2 Radio Strap Test #5 Temperature Data ?
 The sixth and final test conducted did not result in a failure.  This test was conducted using 
Radio A.3 which was used for a previous test in this series as well as one of the radio pocket tests.  
No additional visual damage was noted at the conclusion of this test.  The radio, battery, and 
antenna were also used for testing in the next test series.  The temperature data recorded during 
this test can be seen in Figure 4.46 below. 
 120 
Temperature (?C)
140
120
100
80
60
40
20
0
0 5 10 15 20 25 30 35 40
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.46: 8 ????2 Radio Strap Test #6 Temperature Data 
 While all these radio strap tests were discussed in detail in this subsection, an important 
note is that only two radios failed.  These two radios were of the same model and were sourced 
from the same vendor.  These two radios both failed due to their ?bonks.? It is unknown why these 
radios gave ?bonks? as there was no other audible traffic on the radio frequency.  However, these 
two radios were not moved to a different frequency during their tests.  In the interest of safety and 
to maintain continuality, the radios were left untouched and undisturbed.  However, attempts were 
made constantly during the period, both with immediate activations of the PTT while also allowing 
a period to pass before keying the mic.  The radios did not return to normal until they had reached 
ambient conditions.  The antennas, batteries, and radios themselves all worked after they had 
concluded this cool down phase, and all were used for subsequent testing.  Table 4.7 shows the 
failure time and temperature of both the radios that failed, and Figure 4.47 is generated from this 
table. 
 121 
Temperature (?C)
Table 0.7: 8 ????2 Radio Strap Exposure Failure Time and Temperatures 
Test Radio Exposure Time Failure Temperature Time to Signal Total Test Failure 
to Failure (s) at Battery (?C) Degradation (s)  Duration (s) Mode 
8 ???  A.4 N/A N/A N/A 2220 N/A  ?2
Strap R1 
8 ???  A.3 N/A N/A N/A 2220 N/A ?2
Strap R2 
8 ???  A.4 1740 125.145 1595 2160 ?Bonk? ?2
Strap R3 
8 ???  C.2 N/A N/A N/A 2220 N/A ?2
Strap R4 
8 ???  C.3 1239 126.172 1073 1659 ?Bonk? ?2
Strap R5 
8 ??? A.3 N/A N/A N/A 2220 N/A ?2 
Strap R6 
 
140
Radio 5
120
100
80
60
40
Radio 3
20
0
0 20 40 60 80 100 120 140
Time (min)
 
 122 
Battery Failure Temperature (?C)
Figure 0.47: 8 kW?m2  Radio Strap Failure Temperature vs. Time  
This figure is presented to show the proximity of both the times and temperatures at which 
the radio failed.   
Also, as mentioned above, the ?bonks? were digital failures.  Named for the sound emitted 
by the radios, these are ?busy? signals, signifying to a user who is attempting to key the radio 
microphone that someone else is transmitting on the radio channel.  However, during these 
simulations, when a ?bonk? was heard, the control radio was powered down to see if the radio that 
was being tested would produce this ?busy? signal.  Each time, the radio did immediately 
reproduce this sound, meaning that the radio was not transmitting.  Efforts were also made to 
attempt to transmit a message despite this signal, but these proved to be unsuccessful.  However, 
after the radios cooled, a ?bonk? signal did not manifest itself when the radio was keyed.  
Therefore, while impossible to ascertain the specific component that failed, it would appear 
to be a portion of the computerized internals responsible for the radio to select a channel. 
Next, the battery and temperatures are presented below as Figures 4.48 and 4.49 respectively. 
 123 
250
200
150
100
50
0
0 5 10 15 20 25 30 35 40
Time (min)
Battery Temp 1 (?C) Battery Temp 2 (?C) Battery Temp 3 (?C)
Battery Temp 4 (?C) Battery Temp 5 (?C) Battery Temp 6 (?C)
 
Figure 0.48: 8 ????2  Radio Strap Temperature at Battery 
140
120
100
80
60
40
20
0
0 5 10 15 20 25 30 35 40
Time (min)
Face Temp 1 (?C) Face Temp 2 (?C) Face Temp 3 (?C)
Face Temp 4 (?C) Face Temp 5 (?C) Face Temp 6 (?C)
 
Figure 0.49: 8 ??? 2 Radio Strap Face Temperature  ?
 124 
Temperature (?C) Temperature (?C)
  Again, as done with the radio pocket tests, an effort was made to correlate the failure 
temperatures with the times.  Table 4.8 is included below to summarize the third and fifth radios 
that failed during these radio strap tests.   
Table 0.8: Total Average 8 ????2 Radio Strap Time vs. Tempearture Data 
Test Duration of Exposure (s) Area Under the Battery Failure Time-Temperature Curve 
(? ? s) 
Radio 3 1740 233,600 
Radio 5 1239 356,100 
 
 While there were only two measurements for this test battery, the average value equated to 
294,87 ? 61,227 ? ? s.  As a refresher, the average failure tempearture, when omitting the 
outlying first radio pocket test,  of the radio pocket tests was 289,500 ? 37,270 ? ? s.  When 
these radio strap tests are added to this average, the area beneath the curve averages to 291,100 ?
29,000 ? ? s .  These values will be discussed at the conclusion of the subsection, however it 
would again seem to confirm that the radio temperature at the battery and exposure time are 
signifcant factors to determine when the radio will fail. 
 Furthermore, these tests again exceed the NIST TN 1477 thermal classifications, signifying 
that the radio strap would be a suitable way to carry a portable radio.  Furthermore, due to the 
significantly increased exposure duration for these tests, radio straps would apear to be the superior 
way to carry a radio in terms of thermal protection.  However, the radios would also be exposed 
to a 12 ????2 heat flux, the same heat flux exerted on the radios when held in the radio pocket, 
to verify these findings. 
 125 
1.16.3 12 ????2 Radio Strap Testing 
 While the 8 ????2 heat flux was found for the radio strap positioning, but a 12 
????2 
heat flux was also used to represent the same heat flux used for the radio pocket.  This test series 
produced similar findings from the previous radio strap and the radio pocket tests.  As with the 
previous radio straps, each of these radios was subjected to a maximum of thirty minutes of 
exposure, and if the radio was able to transmit and receive messages for the duration of this 
exposure, then the radio was deemed to have passed the test.   
 The first test that was conducted used one of the radios that had been tested during the 
pocket test as well as during the first set of radio strap tests.  This radio was used to determine the 
lowest time that a radio could be expected to survive.  However, this radio did not fail.  No 
additional visual damage was observed with this radio and the temperature data followed a very 
similar curve, as shown below in Figure 4.50. 
180
160
140
120
100
80
60
40
20
0
0 5 10 15 20 25 30 35 40 45
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.50: 12 ????2 Radio Strap Test #1 Temperature  
 126 
Temperature (?C)
 The second tested radio did fail.  As with all the failure tests in this series, the ?bonk? 
signals could not be overcome.  This radio first gave a ?bonk? just over twenty-two minutes of 
exposure.  The process of attempting to overcome these ?bonks? continued until the test was 
deemed a failure about three minutes later.  The test was allowed to cool for a total of eight minutes 
to allow for the face temperature to return to the levels below that of the battery.  The radio used 
during this test was one of the newer radios that did endure some thermal damage.  The radio 
casing was partially misshapen, but more dramatically, some of the nylon coating inside of the 
radio holster had adhered to the radio.  Images of this radio before and after can be seen in Figures 
4.51 and 4.52 and the temperature data for this radio can be seen below in Figure 4.53.   
  
Figure 0.51: Radio E.4 Thermal Damage Figure 0.52: Radio E.4 Thermal Damage 
After 12 Strap Test #2 After 12 Strap Test #2 Close Up
The curve followed roughly the same shape as the other tests as well, although the 
temperatures remained far lower than the other tests that failed.  This radio, battery, and antenna 
were all able to be used in following tests. 
 127 
160
140
120
100
80
60
40
20
0
0 5 10 15 20 25 30 35
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.53: 12 ????2 Radio Strap Test #2 Temperature Data 
 The third test also was deemed a failure as the radio also emitted a ?bonk? that could not 
be overcome.  This radio had its signal degraded earlier than the any of the other test in this series 
and it also had the earliest failure.  However, no thermal damage was observed after the conclusion 
of this test.  It should also be noted that temperature data followed a somewhat similar shape, but 
the face temperatures were far more erratic, but they do appear to follow the same general trends.  
This temperature data for this report is shown below in Figure 4.54.   
 128 
Temperature (?C)
200
180
160
140
120
100
80
60
40
20
0
0 5 10 15 20 25 30
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.54: 12 ????2 Radio Strap Test #3 Temperature Data 
 The fourth test was conducted with one of the same radios that had been used for multiple 
tests across all the test series, and as with the other tests, this radio did not fail.  Again, no thermal 
damage was seen from this radio.  The temperature data followed roughly the same curves that 
were shown in the previous tests, but the temperature at the battery did reach a higher temperature 
than many of the other tests.  A graph of these values can be seen below in Figure 4.55. 
 129 
Temperature (?C
250
200
150
100
50
0
0 5 10 15 20 25 30 35 40
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.55: 12 ????2 Radio Strap Test #4 Temperature Data 
 The fifth test was also conducted using one of the same radios from the previous tests, and 
like the fourth test in this series, the radio did not fail.  As with before, the radio did not show any 
thermal damage and the temperature data followed the same trends as many of the other radio strap 
tests.  The thermal data can be seen below in Figure 4.56. 
 130 
Temperature (?C)
140
120
100
80
60
40
20
0
0 5 10 15 20 25 30 35 40
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.56: 12 ????2 Radio Strap Test #5 Temperature Data 
 The final test conducted in this series did result in a failure.  This test was conducted with 
one of the radios that were sourced from the same vendor as the others that created the ?bonks.? 
These bonks also resulted in the failure of this radio as well.  The first ?bonk? was observed as the 
radio was keyed at twenty minutes and fifteen seconds of exposure.  However, this signal could 
be overcome more readily than all the other tests.  Seven ?bonk? cycles were produced during this 
test with the radio deemed to fail the test six minutes later.  The temperatures were a bit more 
erratic than some of the other tests, but the curves of these temperatures were well in line with the 
other tests.  A graph of the temperature data from this sixth and final 12 ????2 radio strap test 
is seen below as Figure 4.57. 
 131 
Temperature (?C)
180
160
140
120
100
80
60
40
20
0
0 5 10 15 20 25 30 35
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.57: 12 ????2 Radio Strap Test #6 Temperature Data 
 Finally, as conducted with the previous test series, a summary of the testing can be found 
below.  Table 4.9 below provides the failure time and temperatures while Figure 4.58 shows a 
graphic representation of the table.  Figures 4.59 and 4.60 that follow show the face and the 
temperature at the battery. 
 
 
 
 
 
 
 
 132 
Temperature (?C)
Table 0.9: 12 ????2 Radio Strap Failure Time and Temperatures 
Test Radio Failure Failure Temperature Time to Signal Total Test Failure 
Time (s) at Battery (?C) Degradation (s)  Duration (s) Mode 
12 ???  Strap R1 A.4 N/A N/A N/A 2220 N/A  ?2
12 ???  Strap R2 C.4 1536 147 1327 1956 ?Bonk? ?2
12 ???  Strap R3 C.3 1230 117 1095 1650 ?Bonk? ?2
12 ??? A.3 N/A N/A N/A 2220 N/A  ?2 Strap R4 
12 ???  Strap R5 A.4 N/A N/A N/A 2220 N/A  ?2
12 ???  Strap R6 C.4 1560 149 1215 1980 ?Bonk? ?2
 
160
Radio 6
150
Radio 2
140
130
Radio 3
120
110
100
22 23 24 25 26 27 28
Time (min)
 
Figure 0.58: 12 ????2 Radio Strap Failure Temperature vs. Time  
 133 
Failure Temperature (?C)
250
200
150
100
50
0
0 5 10 15 20 25 30 35 40
Time (min)
Battery Temp 1 (?C) Battery Temp 2 (?C) Battery Temp 3 (?C)
Battery Temp 4  (?C) Battery Temp 5 (?C) Battery Temp 6 (?C)
 
Figure 0.59: 12 ????2 Radio Strap Temperature at the Battery 
200
180
160
140
120
100
80
60
40
20
0
0 5 10 15 20 25 30 35 40
Time (min)
Face Temp 1 (?C) Face Temp 2 (?C) Face Temp 3 (?C)
Face Temp 4 (?C) Face Temp 5 (?C) Face Temp 6 (?C)
  
Figure 0.60: 12 ??? 2 Radio Strap Face Temperature  ?
 134 
Temperature (?C) Temperature (?C
 The final portion of this analysis was to determine the average temperature during the three 
failing simulations.  These averages can be found below in Table 4.10. 
Table 0.10:  Total Average 12 ????2 Radio Strap Time vs. Tempearture Data 
Test Duration of Exposure (s) Area Under the Battery Failure Time-Temperature Curve 
(? ? s) 
Radio 2 1536 221,400 
Radio 3 1230 166,800 
Radio 6 1560 441,200 
 
 Equipped with these averages for each test, the average of the failure 12 ????2 Radio 
Strap tests is 276,500 ? 83,900(? ? s).  Additionally, with these three failures, the failure 
criteria can be calculated for the radio strap tests.  This value averages to 245,500 ?
508,900 (? ? s).   And finally, these additional radios drive the cumulative average of all the 
failure tests to 267,500 ? 30,630(? ? s).   Again, the proximity of these average failure 
temperatures would seem to suggest that the temperature at the battery for a sustained duration is 
what causes the radio to fail, or to emit the ?bonk? signal.  More information on this revelation 
will be discussed in the following chapter. 
1.16.4 Exterior Radio Strap Testing 
 The final tests done in this analysis involved two radios outside of the turnout coat in a 
radio strap.  While this arrangement generally goes against guidance issued to firefighters, this 
arrangement was tested as it remains a somewhat popular method to carry a portable radio.  These 
tests also examined the conditions when the radio was not protected under the turnout coat, but 
rather left exposed.   
 135 
 These two tests were conducted at different incident heat fluxes with the intention of 
examining both the 8 ??? 2 heat flux, and the 12 
??? 2 heat flux that were both tested during ? ?
the original analyses.  Only a single replicate of each test was done as there were not enough 
additional radios or shoulder microphones to conduct a full test battery of six replicates due to 
prohibitive radio costs.  Therefore, an average graph will not be presented in this analysis, but the 
failure findings will be considered in conjunction with the previous tests.  
 Both radios used in this analysis were the radios that provided the ?bonks?.  The radio used 
in the 8 ????2 heat flux analysis had its signal degrade at approximately fifteen minutes of 
exposure.  The radio, antenna, and battery all did function as normal after a cool down period. 
The thermal data produced from this test followed a slightly different profile than the 
previous tests, with a much more erratic face temperature.  These variations are likely due to the 
decreased insulation around the thermocouple.  The thermocouple again melted to this radio, likely 
causing some variations.  The temperatures at battery shown in this test did not reach the ?steady? 
portions of the curve that was seen in the previous trials as the temperatures continued to increase 
throughout the test.  This temperature data is presented below as Figure 4.61. 
 136 
200
180
160
140
120
100
80
60
40
20
0
0 5 10 15 20 25 30
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.61: 8 ????2 Exterior Radio Strap Test Temperature  
 The findings were similar for the analysis conducted of the radio strap assembly directly 
exposed to the 12 ????2 heat flux.  This radio also suffered severe thermal damage.  Interior 
components of the radio were visible at the conclusion of the test and the rubber channel selector 
knob suffered severe deformation.  The antenna was also bent at the conclusion of this test.  
However, the battery and the antenna were able to transmit and receive at the conclusion of the 
test, although the radio was not.  Figures 4.62 through 4.64 below show this damage. 
  
 137 
Temperature (?C)
  
Figure 0.62: Radio E.6 Damage After Figure 0.63: Radio E.6 Melting After 12 
Removal After 12 Strap Outside Test #1 Strap Outside Test #1
 
Figure 0.64: Radio E.6 Melting Close Up After 12 Strap Outside Test #1 
 138 
 The temperature data obtained for this test show results in line with both the previous 
outside radio test as well as the other tests.  However, the temperatures at the battery rapidly 
exceeded the face temperature as it followed the increasing trend until the radio failed about twelve 
minutes after the exposure.  The radio did not give any advanced warning of an impending failure 
as once the significant signal degradation was observed at just under twelve minutes, it could not 
be overcome.  The temperature data from this test is seen below as Figure 4.65.  
200
180
160
140
120
100
80
60
40
20
0
0 5 10 15 20 25 30
Time (min)
Face Temp (?C) Battery Temp (?C)
 
Figure 0.65: 12 ????2 Exterior Radio Strap Test Temperature  
 As previously mentioned, the two temperature graphs will not be compared to each other, 
but Table 4.11 shows the same basic information such as test duration, exposure time to failure, 
and time to signal degradation. 
 
 139 
Temperature (?C)
Table 0.11: Exterior Radio Strap Failure Time and Temperatures 
Test Radio Failure Failure Time to Signal Total Test Failure 
Time (s) Temperature at Degradation Duration Mode 
Battery (?C) (s) (s) 
8 ???  C.5 975 138 900 1395 ?Bonk? ?2
Exterior Strap 
12 ???  C.6 735 196 705 1155 ?Bonk? ?2
Exterior Strap 
 
The same analysis of the time vs. temperature curves conducted in the previous test series 
are shown below in Table 4.12. 
Table 0.12: Average Failure Temperatures for Exterior Radio Strap Tests 
Test Duration of Exposure Area Under the Battery Failure Time-
(s) Temperature Curve (?C*s) 
8 ???  Exterior Strap  975 162,600 ?2
12 ????2Exterior Strap  
735 204,500 
  
 While these temperatures are quite different from each other, this can likely be explained 
both by the time differences, but mainly by the different heat fluxes to which the radios were 
exposed.  The average of these temperatures is 183,500 ? 20,940 ? ? s.  This brings the average 
failure temperature for all radios, excluding the first radio pocket test, to 237,100 ? 21,080 ? ?
s.  While these numbers appear quite large, this is both a function of the heat fluxes as well as the 
exposure times.  Therefore, a standard error that is less than 10% of the mean would seem to imply 
that this correlation is valid.  As discussed previously, the proximity of these measurements would 
 140 
seem to indicate that the temperatures at the battery and the exposure duration are the driving factor 
for the radio to fail. 
1.16.5 Analysis of Repeated Use Radios 
 During this test, five radios were used multiple times.  Images of the radios are presented 
above, along with a description of how each test fared for each radio, but this section is included 
with the intention of listing the results of radios that were exposed multiple times.  Radios A, E.3, 
and E.4 were all used twice while Radio C survived four tests and Radio D surviving five.  All 
these radios failed at least one test. 
 Radio A is of special interest as the radio was used for the first test that only survived an 
exposure of 150 seconds.  As mentioned above, the antenna suffered some damage, but the radio 
remained in usable condition.  However, after the sixth pocket test, this radio failed and exhibited 
severe thermal damage. 
 Radios E.3 and E.4 both were first used during the radio strap tests, with E.3 being used 
during the 8 ????2  series and E.4 first used in the 12
????2 series, where they both failed.  
These two radios failed due to the ?bonk? signal that they produced, a common point of failure for 
all radios of the E series.  A table showing the results of Radio A and these two E series radios is 
presented below as Table 4.13. 
Table 0.13: Results of Radios Used in Two Tests 
 Radio A Radio E.3 Radio E.4 
First Test Pocket Test #1 8 Strap Test #5 12 Strap #2 
Fist Test Failure Time (seconds) 150 1295 1602 
    
Second Test Pocket Test #6 12 Strap Test #3 12 Strap Test #6 
Second Test Failure Time (seconds) 1082 1354 1643 
Table 0.14: Results of Radios Used in Four or More Tests 
 141 
 Radio C Radio D 
First Test Pocket Test #3 Pocket Test #4 
Fist Test Failure Time (seconds) 1503 1101 
   
Second Test 8 Strap Test #2 8 Strap Test #1 
Second Test Failure Time (seconds) N/A N/A 
   
Third Test 8 Strap Test #5 8 Strap Test #3 
Third Test Failure Time (seconds) N/A N/A 
   
Fourth Test 12 Strap Test #4 12 Strap Test #1 
Fourth Test Failure Time (seconds) N/A N/A 
   
Fifth Test N/A 12 Strap Test #5 
Fifth Test Failure Time (seconds) N/A N/A 
1.16.6 Notes on Turnout Coats 
 While not one of the main focuses of this analysis, the turnout coat performance was also 
measured visually.  For this research, two different turnout coats were used.  Both coats had 
incisions made for the radio pocket tests, but these did not appear to have any influence over the 
condition of the coat.  The reason that two different coats were used was due to the rubber 
sheathing of several antennas melting to the coat.  Figures are presented below of both turnout 
coats, but much of the damage was seen on the reflective trim.  This finding would appear to be 
consistent with the Loudon County report discussed in the earlier chapters [43].  In Appendix 7 
which discussing the firefighters? protective equipment, many of the firefighters had the trim either 
charred or completely deteriorated.  As a side note, one of the firefighters also had their, ?Radio 
microphone melted to right side of coat,? while another had, ?a microphone cord that is melted to 
FF?s right front lower cargo pocket.? The main body of the report provides the recommendation, 
 142 
?Encourage a national effort to minimize reflective striping on structural firefighting PPE from 
areas of possible compression.? [43] 
 The same nylon radio strap was used for all the tests, which experienced a significant 
amount of melting.  Figures 4.66 through 4.68 show these results.  The hook and loop closure on 
the radio pockets of both turnout coats also experienced similar results.  During the first tests in 
which these pockets were used, the closures opened and were exposed to the heat flux.  The 
materials then began to melt.  After the first test, the pockets could still be closed, but much more 
effort was required than originally.  After the second test for each coat, the pockets could not be 
closed as the closure materials began to drip.  Images of the pocket can be seen in Figures 4.69 
through 4.71.  Finally, figures of the reflective striping discussed earlier are also shown as Figures 
4.72 through 4.74.   
 
Figure 0.66: Radio Strap Degradation Between Tests
 
 143 
  
  
Figure 0.67: Nylon Radio Strap Label Melted Figure 0.69: Radio Strap and Reflective 
After Testing Trim Damage 
  
  
Figure 0.68: Turnout Coat Radio Pocket Figure 0.70: Radio Pocket Closure Dripping 
Closure Degradation after Pocket Test #1 After Pocket Test #2 
 144 
  
Figure 0.71: Radio Pocket Closure Completely Figure 0.72: Radio Pocket Trim 
Degraded Degradation 
  
Figure 0.73: Trim Degradation and Turnout Figure 0.74: Trim Damage After Strap 
Gear Discoloration Tests 
 
1.16.7 Summary of Failure Times and Temperature 
Finally, a summary can be included for the failures of each radio.  Tables were presented 
above with each testing set of testing, but to coordinate these failure times and temperatures, a 
 145 
table is presented below to show this information.  From Table 4.15 below, Figure 4.75 shows a 
graphical representation of the failure temperatures at the battery and the failure time. 
Table 0.15: Total Radio Failure Time and Temperatures 
Test Radio Failure Failure Time to Signal Total Test Failure Mode 
Time Temperature Degradation Duration 
(s) at Battery (?C) (s)  (s) 
Pocket R1 A.1 224 178 N/A 570 Transmission Failure  
Pocket R2 B 1815 228 525 2168 Transmission Failure  
Pocket R3 A.2 1503 225 600 1854 Transmission Failure  
Pocket R4 A.3 1101 197 465 1422 Transmission Failure  
Pocket R5 C.1 755 225 N/A 1117 Transmission Failure  
Pocket R6 A.1 1082 276 N/A 1425 Transmission Failure  
8 ??? A.4 1740 125 1595 2160 ?Bonk? ?2  
Strap R3 
8 ???   C.3 1239 126 1073 1659 ?Bonk? ?2
Strap R5 
12 ??? C.4 1536 147 1327 1956 ?Bonk? ?2  
Strap R2 
12 ???   C.3 1230 117 1095 1650 ?Bonk? ?2
Strap R3 
12 ????2  
C.4 1560 149 1215 1980 ?Bonk? 
Strap R6 
8 ???   C.5 975 138 900 1395 ?Bonk? ?2
Exterior Strap 
12 ??? C.6 735 196 705 1155 ?Bonk? ?2 
Exterior 
Strap 
 
 146 
300
Pocket R5 Pocket R6
Radio C.1 Radio A.1 Pocket R3 Pocket R2
250
Radio A.2 Radio B
12 kW/m2 Pocket R4
Exterior Radio A.3 12 kW/m2 Strap 
200 Radio C.6 R2
8 kWQ/m2 Strap Radio C.4
R3
150 Radio A.4
8 kW/m2 Exterior
8 kW/m2 Strap 
100 Radio C.5
R3
Radio A.4
12 kW/m2 Strap 
50 R3 12 kW/m
2 Strap 
Pocket R1 Radio C.3 R6
Radio A.1 Radio C.4
0
0 500 1000 1500 2000
Time (s)
 
Figure 0.75: Failure Temperature at Battery and Failure Time Comparison 
 While the graph above shows large disparities between different radios, it does show a few 
trends, especially when coupled with the signal degradation times discussed earlier.  As a trend, 
the highest battery failure temperatures were seen in the radio pocket tests.  While Radio B, tested 
as a part of the radio pocket analysis, had the longest failure time, it should again be noted that this 
radio was the only radio of a different model.  Also, the radios that endured the longest were those 
carried in a radio strap.  These also had the lowest temperatures when they failed, which would 
confirm the hypothesis that wearing the radio beneath the turnout coat would provide superior 
thermal protection.  Finally, wearing the radio in a radio strap above the turnout coat does not 
provide the same protection as wearing the strap beneath the coat.  It also led to more dramatic 
failures as the signal degradation times were far less for these radios than for the other carrying 
methods.
 147 
Failure Temperature at Battery (?C)
Conclusions 
1.17 Final Thoughts 
 With the conclusion of the empirical testing portion of this report, some best practices can 
be gleaned, and some recommendations made to policy makers in the fire service.  Also, it is hoped 
that those involved in the firefighting equipment manufacturing industry and in the standards 
making process would take some recommendations of their own from this research.  The 
recommendations toward the firefighters and to policy makers are listed below. 
1.18 Experimental Program Comments 
As shown above, these radios do show a large disparity in failure time, even in the same 
carrying configuration.  However, the 8 ????2 is not an extreme heat flux, so it is quite alarming 
for these radios to have failed at this lower heat flux.  Therefore, the placement of a radio certainly 
increases the radio?s durability in a fire situation.  While wearing a radio beneath a turnout coat 
will certainly extend the time to failure, it also provides many other benefits outlined in the Fairfax 
County Study [38].  Additionally, wearing a radio in a position where it will remain in its holder 
is preferable as shown in the NIST study.  Wearing a radio in a turnout pocket greatly increases 
the possibility that the radio will become completely exposed and unprotected.  This may prove 
detrimental to the firefighter and implies that wearing a radio in a radio strap is the superior way 
to carry a radio strap. 
Also, while the first radio strap test had a significantly reduced failure time, the heat flux 
varied much like a normal fire situation.  Furthermore, as the radio moves closer to the radiant 
panel, the heat flux was increased.  While this increased heat flux was not determined, it is unlikely 
that the heat flux increased above a 20 ????2 threshold.  Therefore, when a firefighter is exposed 
 148 
to more severe thermal conditions, it is likely that his or her radio will fail.  When a radio fails at 
such a critical juncture, a firefighter may become severely injured or potentially even killed.  While 
thankfully it did not result in a fatality, this situation occurred in the Riverdale Heights incident 
referenced earlier [44].  
1.19 Recommendations to Firefighters 
 Firefighters first need to be able to operate their radio whenever they are engaged in 
dangerous activities, even if only to call for assistance when endangered.  However, firefighters 
often use their radios to communicate when involved in emergency activities.  Therefore, 
firefighters first must be able to always operate their radios.  Firefighters should know the features 
of their radios and be comfortable operating it in uncomfortable conditions.  Firefighters may 
become trapped and have their range of motion compromised, meaning that they might not be able 
to reach a radio.  To achieve this goal of radio proficiency, firefighters must ensure that they train 
with the radios in real world scenarios often. 
 While firefighters may be allowed to choose the side or location where they prefer to wear 
their radio, it is imperative to protect the radio?s battery.  However, this consideration may seem 
to be unnatural, as many would view the screen to be the front of the radio and the battery to be 
the rear, with the desire to protect the screen.  This effort can be especially challenging for the 
radio pocket, as firefighters often place the screen toward themselves while the battery faces the 
outside environment.   Firefighters orient their radios in this way both to provide increased 
visibility to the screen as well as to place the radio in a more comfortable position.  The flat portion 
of the radio is where the screen is generally located, meaning that that end of the radio is the one 
often left to face the firefighter.  Therefore, the battery is left facing the outside environment. 
 149 
 In addition to training, firefighters must be comfortable with how they wear their radios.  
If a fire department requires a firefighter to wear his or her radio in a certain location, then the 
firefighter should be comfortable with that model of radio worn in that location.  However, where 
firefighters have a choice, it would certainly appear that wearing a radio under the turnout coat in 
a radio strap provides the best protection.  As alluded to earlier, firefighters should also be 
comfortable and confident in their ability to change volume or channels when operating in 
dangerous environments.  This proficiency will assist firefighters with overcoming the main 
drawback of this carrying method: having to move the turnout coat to access the channel selector 
and volume knobs on the radio.  If a firefighter is unable to use the knobs with the extremely 
limited dexterity afforded by firefighting gloves, then it may take them longer to make these critical 
changes.  The longer that the firefighter must lift his or her turnout coat, then the longer that the 
station uniform below the turnout gear will be exposed to the environment.  This uniform, mainly 
composed of cotton and polyester work and t-shirts, provides far less thermal protection than 
turnout gear.  Another way to eliminate this potential hazard is found in the section below. 
1.20 Recommendations to Fire Department Policy Makers 
 Fire departments generally use one channel to dispatch their emergency calls, and one 
channel for each large incident.  Some fire departments require their firefighters to transition their 
radios from the dispatch channel to the incident channel when the units first begin to respond while 
others switch channels when firefighters arrive at the incident.  Finally, some departments may not 
switch to an incident channel unless requested to do so.  This may mean that several firefighters 
may already be operating in a dangerous environment before suddenly being required to switch to 
a different channel.   
 150 
 Firefighters also often switch their radios during a MAYDAY incident.  When a firefighter 
becomes trapped, the firefighter, incident commander, and rapid intervention team all work on the 
same channel while the other crews on the scene work on a different channel.  To achieve this, 
some fire departments have the endangered firefighter, rapid intervention team, and officer switch 
channels while the rest of the crews operate on the same channel.  Other agencies do the reverse, 
with the rest of the crews operating on the incident changing channels.  While this allows for two 
complex operations to be conducted simultaneously, it is very important to ensure that all 
firefighters are on the correct channel, and if possible, they should wait to change their channels 
until they are in a safer environment with improved visibility. 
 Fire departments also need to ensure that they are providing their firefighters with adequate 
turnout gear.  While turnout gear is sized a standard firefighter, it is also important to make sure 
that the length is properly measured.  Firefighters will often work with their hands extended above 
their heads, meaning that a turnout coat must be sized larger than a standard coat so that the coat 
will not rise and expose station uniform.  These serves in addition to the comments made earlier 
regarding reflective striping possibly being eliminated. 
Fire departments should also investigate providing their firefighters with radio straps and 
safer equipment such as SCBA mounted microphones.  This equipment can be vital for firefighters 
operating in dangerous environments, as illustrated earlier in this report. 
Finally, fire departments need to evaluate their radios.  While the NFPA 1802 standard is 
evaluating the temperature conditions that a radio will experience in a firefighting environment, it 
will certainly take a long time to be implemented in the fire service.  Many agencies have 
undergone an upgrade to the ?best? radios that were on the market at the time of their upgrade.  
However, these were largely before the NFPA 1802 standard was published.  Now that the standard 
 151 
has been published, and technology continues to advance, radios that are tested in accordance with 
this standard are far more expensive than other radios on the market.  Therefore, it may take many 
more years for radios tested in accordance with this standard to become ?mainstream? in the fire 
service.  Until this development, firefighters and fire departments must be vigilant to ensure that 
portable radios are provided with the greatest protection to ensure that firefighters operate safely 
and efficiently at the fires of today and of tomorrow. 
1.21 Suggestions for Future Research 
While this study focuses on different carrying methods, it is far from comprehensive.  First, 
as noted above in the methodology discussion, no objects were placed under the turnout coat.  
While placing a person inside of the turnout coat would serve to better represent the realistic 
situation, it was not deemed a safe for test tests.  However, in the absence of a firefighter, no 
thermal mass was located behind the turnout coat.  This mass would likely consume some of the 
thermal energy that remained in the radio pocket or strap assembly.  This may increase the time to 
failure for each of these radios.  Additionally, care should be taken to quantify the thermal 
conductivity, thickness, and air gap width of the turnout gear and the radio holder assembly.  This 
will allow for a specific heat transfer analysis to be conducted for each case.  In this test series, 
two turnout coats were used with different air gap thicknesses and thermal conductivity, 
eliminating the possibility for an accurate analysis.  
In terms of quantities to identify, the orientation of the battery will factor into the radio?s 
failure time.  Therefore, further research should be conducted to determine the impact of this 
positioning.  Furthermore, research into specific holders should be conducted.  Different leather 
radio strap manufacturers produce various types of holsters.  Some other manufacturers may also 
use thicker leather on certain radio holsters, which would provide more thermal protection than 
 152 
others.  This research could also be updated with more modern radios.  Additionally, using only 
one type of radio may also prove beneficial.  This may eliminate the thermal soak differences.  An 
analysis of a similar nature should also be done to the shoulder microphone assembly.  This portion 
of the radio apparatus has been deemed to be the ?weakest link? in the assembly, so this would 
likely provide shorter failure times than identified in this research.  Finally, determining the 
transmission capability through walls and other structural components can be researched.  The 
testing conducted above replicates a scenario seldom seen in the fire service.  Positioning the target 
radio behind a simulated wall could dramatically alter the results as the signal at the control radio 
would likely be far weaker. 
 153 
Appendices 
Appendix A: Living Room FDS Simulation Input File 
&HEAD CHID='Couch', TITLE='Couch'  / 
 
&MESH IJK=31,31,31, XB=0.75,3.85,3.45,6.55,0.0,3.1 / 
 
&TIME T_END=600. / 
 
&REAC SOOT_YIELD=0.01,FUEL='PROPANE'/ 
&MATL ID                    = 'FABRIC' 
      FYI                   = 'Properties completely fabricated' 
      SPECIFIC_HEAT         = 1.0 
      CONDUCTIVITY          = 0.1 
      DENSITY               = 100.0 
      N_REACTIONS           = 1 
      NU_SPEC               = 1. 
      SPEC_ID               = 'PROPANE' 
      REFERENCE_TEMPERATURE = 320. 
      HEAT_OF_REACTION      = 3000. 
      HEAT_OF_COMBUSTION    = 20000. / 
 
&MATL ID                    = 'FOAM' 
      FYI                   = 'Properties completely fabricated' 
      SPECIFIC_HEAT         = 1.0 
      CONDUCTIVITY          = 0.05 
      DENSITY               = 40.0 
      N_REACTIONS           = 1 
      NU_SPEC               = 1. 
      SPEC_ID               = 'PROPANE' 
      REFERENCE_TEMPERATURE = 320. 
      HEAT_OF_REACTION      = 1500. 
      HEAT_OF_COMBUSTION    = 30000. / 
 
&MATL ID            = 'GYPSUM PLASTER' 
      FYI           = 'Quintiere, Fire Behavior' 
      CONDUCTIVITY  = 0.48 
      SPECIFIC_HEAT = 0.84 
      DENSITY       = 1440. / 
 
&SURF ID             = 'UPHOLSTERY' 
      FYI            = 'Properties completely fabricated' 
      COLOR          = 'PURPLE' 
 154 
      BURN_AWAY      = .TRUE. 
      MATL_ID(1:2,1) = 'FABRIC','FOAM' 
      THICKNESS(1:2) = 0.002,0.1  / 
 
&SURF ID             = 'WALL' 
      DEFAULT        = .TRUE. 
      RGB            = 200,200,200 
      MATL_ID        = 'GYPSUM PLASTER' 
      THICKNESS      = 0.012 / 
 
 
&OBST XB= 1.50, 3.10, 5.80, 6.60, 0.00, 0.40 / 
&OBST XB= 1.50, 3.10, 5.80, 6.60, 0.40, 0.60, SURF_ID='UPHOLSTERY', 
BULK_DENSITY=41.176 / 
&OBST XB= 1.30, 1.50, 5.80, 6.60, 0.00, 0.90, SURF_ID='UPHOLSTERY', 
BULK_DENSITY=41.176 / 
&OBST XB= 3.10, 3.30, 5.80, 6.60, 0.00, 0.90, SURF_ID='UPHOLSTERY', 
BULK_DENSITY=41.176 / 
&OBST XB= 1.50, 3.10, 6.35, 6.60, 0.60, 1.20, SURF_ID='UPHOLSTERY', 
BULK_DENSITY=41.176 / 
&OBST XB= 0.78, 3.82, 3.49, 3.5, 0.0, 2.5, SURF_ID='WALL', BULK_DENSITY=41.176 / 
&OBST XB= 0.78, 3.82, 6.54, 6.55, 0.0, 2.5, SURF_ID='WALL', BULK_DENSITY=41.176 / 
&OBST XB= 0.77, 0.78, 3.5, 6.55, 0.0, 2.5, SURF_ID='WALL', BULK_DENSITY=41.176 / 
&OBST XB= 3.81, 3.82, 3.5, 6.55, 0.0, 2.5, SURF_ID='WALL', BULK_DENSITY=41.176 / 
&OBST XB= 0.78, 3.82, 3.5, 3.55, 0.0, 0.1, SURF_ID='WALL', BULK_DENSITY=41.176 / 
&OBST XB= 0.78, 3.82, 3.5, 6.55, 2.4, 2.5, SURF_ID='WALL', BULK_DENSITY=41.176 / 
 
&PART ID='ignitor particle', SURF_ID='ignitor', STATIC=.TRUE. / 
&SURF ID='ignitor', TMP_FRONT=1000., GEOMETRY='CYLINDRICAL', LENGTH=0.15, 
RADIUS=0.01 / 
&INIT XYZ=2.45,6.30,0.65, DX=0.1, PART_ID='ignitor particle', N_PARTICLES=3 / 
 
&VENT MB='XMIN', SURF_ID='OPEN' /   
&VENT MB='XMAX', SURF_ID='OPEN' /   
 
&HOLE XB=1.84,2.76,3.44,3.56,0.0,2.13/ 
&HOLE XB=0.74,0.8,4.73,5.33,1.0,2.0/ 
 
&BNDF QUANTITY='RADIATIVE HEAT FLUX' / 
&BNDF QUANTITY='CONVECTIVE HEAT FLUX' / 
&BNDF QUANTITY='NET HEAT FLUX' / 
&BNDF QUANTITY='WALL TEMPERATURE' / 
&BNDF QUANTITY='BURNING RATE' / 
 
&SLCF PBX=2.50, QUANTITY='TEMPERATURE',VECTOR=.TRUE., 
CELL_CENTERED=.TRUE. / 
 155 
&SLCF PBX=2.50, QUANTITY='HRRPUV', CELL_CENTERED=.TRUE. / 
&SLCF PBX=2.50, QUANTITY='RADIATION LOSS', CELL_CENTERED=.TRUE. / 
&SLCF PBX=2.50, QUANTITY='VISCOSITY', CELL_CENTERED=.TRUE. / 
&SLCF PBY=4.40, QUANTITY='TEMPERATURE',VECTOR=.TRUE., 
CELL_CENTERED=.TRUE. / 
&SLCF PBY=4.40, QUANTITY='HRRPUV', CELL_CENTERED=.TRUE. / 
&SLCF PBY=4.40, QUANTITY='RADIATION LOSS', CELL_CENTERED=.TRUE. / 
 
&DEVC ID='Tree_1_T1', QUANTITY='THERMOCOUPLE', XYZ=2.63,5.13,0.31/ 
&DEVC ID='Tree_1_T2', QUANTITY='THERMOCOUPLE', XYZ=2.63,5.13,0.62/ 
&DEVC ID='Tree_1_T3', QUANTITY='THERMOCOUPLE', XYZ=2.63,5.13,0.93/ 
&DEVC ID='Tree_1_T4', QUANTITY='THERMOCOUPLE', XYZ=2.63,5.13,1.24/ 
&DEVC ID='Tree_1_T5', QUANTITY='THERMOCOUPLE', XYZ=2.63,5.13,1.55/ 
&DEVC ID='Tree_1_T6', QUANTITY='THERMOCOUPLE', XYZ=2.63,5.13,1.86/ 
&DEVC ID='Tree_1_T7', QUANTITY='THERMOCOUPLE', XYZ=2.63,5.13,2.17/ 
&DEVC ID='Tree_1_T8', QUANTITY='THERMOCOUPLE', XYZ=2.63,5.13,2.48/ 
 
&DEVC XYZ=2.63,4.2,0.25, QUANTITY='INTEGRATED INTENSITY', ID='FF1Crawl' / 
&DEVC XYZ=2.63,4.45,0.89, QUANTITY='INTEGRATED INTENSITY', ID='FF1Standing' / 
&DEVC XYZ=2.63,4.7,0.51, QUANTITY='INTEGRATED INTENSITY', ID='FF2Crawl' / 
&DEVC XYZ=2.63,4.45,0.91, QUANTITY='INTEGRATED INTENSITY', ID='FF2Standing' / 
&DEVC XYZ=2.63,4.45,0.74, QUANTITY='INTEGRATED INTENSITY', ID='FF3Crawl' / 
&DEVC XYZ=2.63,4.45,1.3, QUANTITY='INTEGRATED INTENSITY', ID='FF3Standing' / 
&DEVC XYZ=2.63,4.2,0.33, QUANTITY='INTEGRATED INTENSITY', ID='FF4Crawl' / 
&DEVC XYZ=2.63,4.45,0.94, QUANTITY='INTEGRATED INTENSITY', ID='FF4Standing' / 
&DEVC XYZ=2.63,4.45,0.51, QUANTITY='INTEGRATED INTENSITY', ID='FF5Crawl' / 
&DEVC XYZ=2.63,4.45,0.86, QUANTITY='INTEGRATED INTENSITY', ID='FF5Standing' / 
&DEVC XYZ=2.63,4.7,0.53, QUANTITY='INTEGRATED INTENSITY', ID='FF6Crawl' / 
&DEVC XYZ=2.63,4.45,0.76, QUANTITY='INTEGRATED INTENSITY', ID='FF6Standing' / 
&DEVC XYZ=2.63,4.2,0.25, QUANTITY='INTEGRATED INTENSITY', ID='FF7Crawl' / 
&DEVC XYZ=2.63,4.45,0.76, QUANTITY='INTEGRATED INTENSITY', ID='FF7Standing' / 
&DEVC XYZ=2.63,4.7,0.81, QUANTITY='INTEGRATED INTENSITY', ID='FF9Crawling' / 
&DEVC XYZ=2.63,4.45,1.04, QUANTITY='INTEGRATED INTENSITY', ID='FF8Standing' / 
&DEVC XYZ=2.63,4.5,0.4, QUANTITY='HRRPUV', ID='HRRPUV' / 
&DEVC ID='FF1Crawl_TC', QUANTITY='THERMOCOUPLE', XYZ=2.63,4.2,0.25/ 
&DEVC ID='FF2Crawl_TC', QUANTITY='THERMOCOUPLE', XYZ=2.63,4.7,0.51/ 
&DEVC ID='FF3Crawl_TC', QUANTITY='THERMOCOUPLE', XYZ=2.63,4.45,0.74/ 
&DEVC ID='FF4Crawl_TC', QUANTITY='THERMOCOUPLE', XYZ=2.63,4.2,0.33/ 
&DEVC ID='FF5Crawl_TC', QUANTITY='THERMOCOUPLE', XYZ=2.63,4.45,0.51/ 
&DEVC ID='FF6Crawl_TC', QUANTITY='THERMOCOUPLE', XYZ=2.63,4.7,0.53/ 
&DEVC ID='FF7Crawl_TC', QUANTITY='THERMOCOUPLE', XYZ=2.63,4.2,0.25/ 
&DEVC ID='FF8Crawl_TC', QUANTITY='THERMOCOUPLE', XYZ=2.63,4.7,0.81/ 
&DEVC ID='FF1Stand_TC', QUANTITY='THERMOCOUPLE', XYZ=2.63,4.45,0.89/ 
&DEVC ID='FF2Stand_TC', QUANTITY='THERMOCOUPLE', XYZ=2.63,4.45,0.91/ 
&DEVC ID='FF3Stand_TC', QUANTITY='THERMOCOUPLE', XYZ=2.63,4.45,1.3/ 
&DEVC ID='FF4Stand_TC', QUANTITY='THERMOCOUPLE', XYZ=2.63,4.45,0.94/ 
 156 
&DEVC ID='FF5Stand_TC', QUANTITY='THERMOCOUPLE', XYZ=2.63,4.45,0.86/ 
&DEVC ID='FF6Stand_TC', QUANTITY='THERMOCOUPLE', XYZ=2.63,4.45,0.76/ 
&DEVC ID='FF7Stand_TC', QUANTITY='THERMOCOUPLE', XYZ=2.63,4.45,0.76/ 
&DEVC ID='FF8Stand_TC', QUANTITY='THERMOCOUPLE', XYZ=2.63,4.45,1.04/ 
 
&TAIL / 
 157 
Appendix B: Bedroom FDS Simulation Input File 
&HEAD CHID='Bed', TITLE='Bed'  / 
 
&MESH IJK=31,46,31, XB=0.75,3.85,2.0,6.6,0.0,3.1 / 
 
&TIME T_END=600. / 
 
&REAC ID='POLYURETHANE', 
      FYI='FM SNL FDS5 Validation', 
      FUEL='REAC_FUEL', 
      FORMULA='C17H16N2O4', 
      SOOT_YIELD=0.02/ 
 
&MATL ID            = 'GYPSUM PLASTER' 
      FYI           = 'Quintiere, Fire Behavior' 
      CONDUCTIVITY  = 0.48 
      SPECIFIC_HEAT = 0.84 
      DENSITY       = 1440. / 
 
&SURF ID             = 'Fire' 
      FYI            = 'Properties completely fabricated' 
      COLOR          = 'RED' 
      HRRPUA         = 184, 
      TAU_Q      =-240.0, 
      TMP_FRONT      = 300.0/ 
 
&SURF ID             = 'WALL' 
      DEFAULT        = .TRUE. 
      RGB            = 200,200,200 
      MATL_ID        = 'GYPSUM PLASTER' 
      THICKNESS      = 0.012 / 
 
&OBST XB= 1.3335, 3.265, 4.01, 6.60, 0.00, 0.90 / 
&OBST XB= 0.78, 3.82, 1.99, 2.01, 0.0, 2.5, SURF_ID='WALL', BULK_DENSITY=41.176 / 
&OBST XB= 0.78, 3.82, 6.59, 6.6, 0.0, 2.5, SURF_ID='WALL', BULK_DENSITY=41.176 / 
&OBST XB= 0.77, 0.78, 2.0, 6.6, 0.0, 2.5, SURF_ID='WALL', BULK_DENSITY=41.176 / 
&OBST XB= 3.81, 3.82, 2.0, 6.6, 0.0, 2.5, SURF_ID='WALL', BULK_DENSITY=41.176 / 
&OBST XB= 0.78, 3.82, 2.0, 6.6, 0.0, 0.1, SURF_ID='WALL', BULK_DENSITY=41.176 / 
&OBST XB= 0.78, 3.82, 2.0, 6.6, 2.4, 2.5, SURF_ID='WALL', BULK_DENSITY=41.176 / 
 
&VENT MB='XMIN', SURF_ID='OPEN' /   
&VENT MB='XMAX', SURF_ID='OPEN' /  
&VENT ID='burner vent', SURF_ID='Fire', XB=1.3335,3.265,4.01,6.60,0.9,0.9, COLOR='RED'/  
 
&HOLE XB=1.84,2.76,1.98,2.02,0.0,2.13/ 
 158 
&HOLE XB=0.74,0.8,4.73,5.33,1.0,2.0/ 
&HOLE XB=3.80,3.86,4.73,5.33,1.0,2.0/ 
 
&BNDF QUANTITY='RADIATIVE HEAT FLUX' / 
&BNDF QUANTITY='CONVECTIVE HEAT FLUX' / 
&BNDF QUANTITY='NET HEAT FLUX' / 
&BNDF QUANTITY='WALL TEMPERATURE' / 
&BNDF QUANTITY='BURNING RATE' / 
 
&SLCF PBX=2.50, QUANTITY='TEMPERATURE',VECTOR=.TRUE., 
CELL_CENTERED=.TRUE. / 
&SLCF PBX=2.50, QUANTITY='HRRPUV', CELL_CENTERED=.TRUE. / 
&SLCF PBX=2.50, QUANTITY='RADIATION LOSS', CELL_CENTERED=.TRUE. / 
&SLCF PBX=2.50, QUANTITY='VISCOSITY', CELL_CENTERED=.TRUE. / 
&SLCF PBY=4.40, QUANTITY='TEMPERATURE',VECTOR=.TRUE., 
CELL_CENTERED=.TRUE. / 
&SLCF PBY=4.40, QUANTITY='HRRPUV', CELL_CENTERED=.TRUE. / 
&SLCF PBY=4.40, QUANTITY='RADIATION LOSS', CELL_CENTERED=.TRUE. / 
 
&DEVC ID='Tree_1_T1', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.5,0.31/ 
&DEVC ID='Tree_1_T2', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.5,0.62/ 
&DEVC ID='Tree_1_T3', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.5,0.93/ 
&DEVC ID='Tree_1_T4', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.5,1.24/ 
&DEVC ID='Tree_1_T5', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.5,1.55/ 
&DEVC ID='Tree_1_T6', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.5,1.86/ 
&DEVC ID='Tree_1_T7', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.5,2.17/ 
&DEVC ID='Tree_1_T8', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.5,2.48/ 
 
&DEVC XYZ=2.3,2.41,0.25, QUANTITY='INTEGRATED INTENSITY', ID='FF1Crawl' / 
&DEVC XYZ=2.3,2.66,0.89, QUANTITY='INTEGRATED INTENSITY', ID='FF1Standing' / 
&DEVC XYZ=2.3,2.91,0.51, QUANTITY='INTEGRATED INTENSITY', ID='FF2Crawl' / 
&DEVC XYZ=2.3,2.66,0.91, QUANTITY='INTEGRATED INTENSITY', ID='FF2Standing' / 
&DEVC XYZ=2.3,2.66,0.74, QUANTITY='INTEGRATED INTENSITY', ID='FF3Crawl' / 
&DEVC XYZ=2.3,2.66,1.3, QUANTITY='INTEGRATED INTENSITY', ID='FF3Standing' / 
&DEVC XYZ=2.3,2.41,0.33, QUANTITY='INTEGRATED INTENSITY', ID='FF4Crawl' / 
&DEVC XYZ=2.3,2.66,0.94, QUANTITY='INTEGRATED INTENSITY', ID='FF4Standing' / 
&DEVC XYZ=2.3,2.66,0.51, QUANTITY='INTEGRATED INTENSITY', ID='FF5Crawl' / 
&DEVC XYZ=2.3,2.66,0.86, QUANTITY='INTEGRATED INTENSITY', ID='FF5Standing' / 
&DEVC XYZ=2.3,2.91,0.53, QUANTITY='INTEGRATED INTENSITY', ID='FF6Crawl' / 
&DEVC XYZ=2.3,2.66,0.76, QUANTITY='INTEGRATED INTENSITY', ID='FF6Standing' / 
&DEVC XYZ=2.3,2.41,0.25, QUANTITY='INTEGRATED INTENSITY', ID='FF7Crawl' / 
&DEVC XYZ=2.3,2.66,0.76, QUANTITY='INTEGRATED INTENSITY', ID='FF7Standing' / 
&DEVC XYZ=2.3,2.91,0.81, QUANTITY='INTEGRATED INTENSITY', ID='FF8Crawl' / 
&DEVC XYZ=2.3,2.66,1.04, QUANTITY='INTEGRATED INTENSITY', ID='FF8Standing' / 
&DEVC XYZ=2.3,2.5,0.4, QUANTITY='HRRPUV', ID='HRRPUV' / 
&DEVC ID='FF1Crawl_TC', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.41,0.25/ 
 159 
&DEVC ID='FF2Crawl_TC', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.91,0.51/ 
&DEVC ID='FF3Crawl_TC', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.66,0.74/ 
&DEVC ID='FF4Crawl_TC', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.41,0.33/ 
&DEVC ID='FF5Crawl_TC', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.66,0.51/ 
&DEVC ID='FF6Crawl_TC', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.91,0.53/ 
&DEVC ID='FF7Crawl_TC', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.91,0.25/ 
&DEVC ID='FF8Crawl_TC', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.91,0.81/ 
&DEVC ID='FF1Stand_TC', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.66,0.89/ 
&DEVC ID='FF2Stand_TC', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.66,0.91/ 
&DEVC ID='FF3Stand_TC', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.66,1.3/ 
&DEVC ID='FF4Stand_TC', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.66,0.94/ 
&DEVC ID='FF5Stand_TC', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.66,0.86/ 
&DEVC ID='FF6Stand_TC', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.66,0.76/ 
&DEVC ID='FF7Stand_TC', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.66,0.76/ 
&DEVC ID='FF9Stand_TC', QUANTITY='THERMOCOUPLE', XYZ=2.3,2.66,1.04/ 
 
&TAIL / 
 160 
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