This post was inspired by wirelesswalker at yahoo.com and gregcarttar at 3rd-st.com who posted very similar articles to an Internet mailing list.

On April 16. 2007 firefighter/technician Kyle Wilson died while fighting a residential structure fire in Woodbridge, Virginia. Communications problems associated with the use of a digital trunked radio system contributed to the tragedy. Prince William County Department of Fire and Rescue just released a detailed report on the incident. The County uses a Motorola digital trunked radio system.

According to the report, fire service safety advocates are encouraging colleagues everywhere to study this incident in hopes of similar tragedies being avoided in the future. Audio recordings of radio traffic and video of the fireground have been made available, including the the chilling transmissions of Firefighter Wilson advising that he was trapped. Within the audio, you will hear Firefighter Wilson advising that he was trapped, with his words “Mayday, Mayday, Mayday, Tower 512 bucket, I’m trapped inside, I don’t know where I am, I’m somewhere in the stairwell, I need someone to come get me out!!”

Numerous personnel reported operational problems with their portable radios. These problems were described as:

• Signal distortion and transmission capability failure.

• Receiving capability failure.

• Inoperable radio.

• One radio displayed “out of range.”

• Radios self transmitting (open microphones).

• Dead batteries that occurred during use on the fire ground.

On the incident the following personnel reported portable radio failures during their interviews:

• Wagon 512 officer – stopped transmitting and receiving.

• Wagon 512 bucket – stopped transmitting.

• Rescue 510 officer – displayed out of range.

• Rescue 510 officer’s bucket – stopped transmitting and receiving.

• Rescue 510 driver’s bucket – stopped transmitting and receiving.

• Safety 502 – stopped transmitting and receiving.

• Battalion 502 – signal distortion and stopped transmitting.

• Wagon 502 officer – signal distortion.

• Tower 513 officer – stopped receiving.

The 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.

The Department took immediate action following the Marsh Overlook incident to further assess and identify the weaknesses of the portable radios by conducting a radio test procedure. All users were advised of the vulnerabilities of the radio. Procedures were identified to troubleshoot the device when operational difficulties are encountered. The following weaknesses and vulnerabilities were noted:

• When the Motorola ASTRO XTS 5000 Model II and ASTRO XTS 5000R Model III portable radios were exposed to water fog during testing, there was a significant loss of communication capability that is inconsistent with the needs of emergency responders.

• The loss of communication capability occurred with or without the use of any extended microphone accessories tested.

• Audio transmissions become distorted when water physically struck the radio.

• There was additional audio signal degradation when water continued to impact the speaker area of the portable radio. This condition was exacerbated when the extended microphones were utilized.

• Either one of these issues, independent of the other, can cause and affect communication failure during radio use. A failure was defined as preventing effective communications of simple messages from sender to receiver.

Currently, the International Association of Fire Chiefs has commissioned a digital noise interference task force which is evaluating industry wide concerns with the technology that is currently in use and available for the fire and rescue industry. Prince William County’s findings have been forwarded to that group for inclusion in the process. Efforts to identify potential solutions to the communication issues continue to date.

Prince William County is located in the Commonwealth of Virginia and is part of the Washington metropolitan area. The county has a total area of 348 square miles and an estimated population of 357,500.

My Recommendation:

1. Do not use repeater operation on a fireground.

2. Do not use trunked radio operation on a fireground. (“out of range” could only have come from a trunked system.)

3. Do not use digital modulation for fireground radio communication. Current, vocoder technology cannot tolerate the noisy environment.

4. Use only analog, simplex radio operation on a fireground.

5. Waterproof radios may be waterproof and may survive water immersion or inundation, but standard acoustic microphone elements are not. If you get water into them, they may continue to work and survive, but they become unclear. Water is a lousy acoustic propagation medium. Consider using non-acoustic microphones.

Click on the following links for more information.

Prince William County Fire LODD Report (382 page PDF)

Prince William County Fire LODD Radio Audio and Video (20 MB video)

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