There have been several recent newspaper articles about Hamilton County firefighters and the problems they’ve reported with fire scene communication. We thought it would be helpful to our users to review some best practices and clarify misconceptions in the media reports.
Two articles in today’s Cincinnati Enquirer allege the system used by Cincinnati firefighters failed during recent fires. In reality, they’re speaking of several distinct and separate issues, including:
- the ability of digital radios to isolate and transmit a voice in high-noise environments
- coverage in densely constructed downtown Cincinnati high-rises
- multiple firefighters trying to transmit at the same time
- “busy signals” experienced when all channels are in use; and
- mayday calls not being heard on the fireground.
While these issues are presented together, each must be examined separately.
Digital Radios in High Noise Environments
The International Association of Fire Chiefs (IAFC) formed a digital working group in 2007 to address potential problems found in digital radios in the presence of loud background noise. In the early years of digital public safety radios, the audio processing hardware and software in the radio did a poor job picking the voice out of background noise like chain saws and PASS alarms.
The IAFC working group, comprised of fire-service personnel and manufacturers, studied the issue to develop reliable data to address the extent and nature of the problem.
As a result, Motorola has made several improvements to the hardware and software that, while not perfect, do greatly improve voice quality during those situations. Motorola also issued a recommendation in 2008 for best practices in programming radios with settings for high noise environments, all of which have been incorporated in Butler County radios. Testing conducted by the Hamilton Fire Department, in conjunction with BRICS system administrators, demonstrated that these settings made a significant improvement in high noise environments. Radios with the recommended settings were tested against those without, in situations with SCBA and PASS alarms.
The IAFC released an interim report on their findings, which recommends many best practices for fire department leadership and radio field users.
The leaders were charged with training “all personnel to properly use the assigned radio equipment in conjunction with all components of the protective ensemble.” They pointed out the need for “scenario-based user training utilizing their communication equipment,” and “integration of communication policies and procedures into agency operations.”
Field users were advised to, when practical:
- use the radio for the initial distress call before manually activating the PASS alarm in a mayday situation.
- ensure the microphone is placed one to two inches from the mouth or SCBA voice port with the microphone positioned directly in front of the audio source
- speak in a loud, clear and controlled voice to maximize audio intelligibility
- shield the microphone from noise sources to improve the intelligibility of the audio in high-noise environments
To read the full list of recommendations, you can download the report and presentation from our Best Practices in High Noise Environments page.
Coverage in Dense Buildings
No radio system can cover every part of every building. Our system was designed to provide 95% coverage for portable radios in 15db buildings and, upon completion, tested at over 97%. We thought it was important to involve local agencies in the coverage testing and had good participation throughout the county.
We recommend making radio coverage testing a part of your fire preplanning efforts. Knowing gaps in coverage ahead of time will allow the incident commander to plan accordingly in using conventional simplex channels programmed in every Butler County radio.
Local governments around the country have included this in their building codes, requiring new construction to demonstrate that public safety radios will work inside or add amplifiers to accommodate them. Large buildings already install amplifiers so cell phones work inside; encourage them to include public safety.
Busy Signals vs. Multiple Users Trying to Talk
Cited as a failure of the radio system, media reports point out that users of Hamilton County’s system get “busy signals” when others are talking. There are actually two different situations that sound the same: either the system can be busy (every channel across the system is in use) or someone else can be talking on your selected talkgroup. In either case, you can’t transmit and your radio tells you so – with two different tones. This is not a failure; it’s by design.
Radios are typically “half duplex”, meaning you can either receive or transmit, but you can’t do both. This works the same way on our new system and Hamilton County’s system. Having to wait your turn to talk is nothing new.
Analog systems, including what both we and Hamilton County used before digital, perform the same way. If two people tried to talk on the old system, only one got through. Both thought they were heard, but only one signal made it over the channel. The difference with the new system is you actually know whether your message will be transmitted, because you get immediate confirmation with either the chirp that tells you to proceed, or the tone that tells you to wait. It’s an improvement over analog.
Maydays
A Cincinnati Enquirer article titled “Mayday Call Met with Silence on Radio” describes a situation where two firefighters became trapped by a burning stairwell. One of the firefighters declared “Mayday, mayday, mayday,” according to the article, and received no response from the incident commander. Responding apparatus heard the mayday call and answered the distress call. Three minutes elapsed before a rescue operation was initiated.
The fact that the mayday was heard by other users demonstrates that the call went through, but was missed by the incident commander for reasons unknown.
This scenario is what guided our decision to have emergency buttons revert to the main talkgroup. If our users are unsuccessful at declaring a mayday on the fireground, activating the emergency alarm feature will take them to a dispatch center on the main talkgroup, guaranteeing they will be heard.
Our recommendation is to vocally declare your mayday on the fireground first, to alert incident command to your situation. If your call goes unanswered, use the emergency alarm. A dispatcher will coordinate with commanders to initiate a rescue effort.
Summary
We thought it was important to respond to this because we knew many of our users would see the articles and have questions concerning the applicability to our system. Hamilton County was very open with us and helped a great deal during the planning stages of our system. Both systems are Motorola Astro 25 and, for the field users, essentially operate the same. The main difference in Butler County is, with the benefit of having programmed our radios in 2009, we were able to take advantage of the best practices for noise reduction, issued by Motorola in 2008. With the input of Motorola, our partner systems and user community, we believe our radios are programmed with the best available settings and capabilities for fireground safety.
Related Downloads
Digital Portable Radio Best Practices Presentation – IAFC
Best practices guide published by the International Association of Fire Chiefs on how to minimize or eliminate background noise problems while using digitial radios.
Digital Problem Working Group, Interim Report – IAFC
Interim report, issued in May 2008 by the International Association of Fire Chief’s Digital Problem Working Group.
Background Noise and Radio Performance – Motorola
Best practices help firefighters and other first responders maximize the intelligibility of two-way radio communications in high-noise environments.
Newspaper Articles
Dropped Calls Put Firefighters in Danger (PDF)
Cincinnati Enquirer | Printed January 15, 2010 | web link
Mayday Call Met with Silence on Radio (PDF)
Cincinnati Enquirer | Printed January 15, 2010 | web link
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