Preventing Freewheeling of Public Safety Portable Radio VolumePower Knob 

RECOMMENDATIONS 

The NIOSH Fire Fighter Fatality Investigation and Prevention Program 

(FFFIPP) recommends fire departments ensure all firefighter portable radio 

volume-power knobs cannot be accidentally turned down or off while 

responding to or on the scene of an incident. To ensure the proper working 

conditions and use of portable radios, departments should make sure that 

firefighters: 

 Recognize that the volume-power knob may be unintentionally turned

down or off on some portable radios by movement from the firefighter’s

turnout coat and/or tools contacting and turning the power-volume

knob.

 Consider upgrading to portable radios with function knobs located

on top of the radios, knobs of different size with detents at each

position with hard stops, and knobs that are resistant to accidental

turning.

Firefighter Using Portable Radio 

Photo by © moodboard/Getty Images 

FFFIPP INVESTIGATION 

On January 5, 2020, a fire department responded to a dryer fire at a modular home. Two firefighters in 

full personal protective equipment made entry into the structure with a hoseline with visibility conditions 

eventually turning to zero. Conditions worsened further and the firefighter on the nozzle fell through the 

floor. The captain, several feet behind the firefighter, was struck by debris and was unaware the firefighter 

fell through the floor. The communications that took place inside and outside the structure to Command 

were primarily face to face or shouting because of past experience with the volume-power knob freely 

spinning to off or low volume with the department’s Motorola APX 6000 handheld radios. Several 

attempts were made to locate the firefighter, but heavy fire hindered rapid intervention team operations. 

After the fire was knocked down, the firefighter was located in the basement with a radio in his 

possession. He was taken to the hospital where he was pronounced deceased. As part of the NIOSH 

investigation, the firefighter’s portable radio was inspected. Investigators could not confirm the position of 

the knob at the time of the incident but noted the volume-power knob could freewheel (spin freely). Freewheeling is known to have hindered fireground communication during past incidents and may have 

prevented a Mayday from being communicated by the firefighter. 

QUESTIONS & ANSWERS on p. 2 
 Preventing Freewheeling of Public Safety Portable Radio VolumePower Knob

QUESTIONS & ANSWERS

Why does the volume-power knob inadvertently move? 

There is a small O-ring under the knob that provides friction. Some O-rings may have insufficient friction, allowing

the volume-power knob to move freely as a result of contact with the inner lining of the turnout coat and/or tools 

when the radio is in a holster or pocket. 

What are the solutions for inadvertent volume-power knob movement? 

1. Some newer models come with higher friction O-rings. Older model portable radios with a free moving

control knob can be retrofited to increase the resistance by replacing the O-ring in accordance with the

manufacturer’s guidance. See the manufacturer’s installation guide for information on how to change these

O-rings.

2. Consideration should be given to the purchase and use of ruggedized radios and accessories developed for

the fire fighting environment per NFPA 1802.

What is the NFPA 1802: Standard on Two-Way, Portable RF Voice Communications Devices for Use by 

Emergency Services Personnel in the Hazard Zone? 

This standard, released in early 2021, aims to make portable radios more environmentally rugged and 

enhance their overall performance. Recommended radio upgrades include ergonomic improvements to 

knobs and locations. The function knobs should be located on top of the radio, each knob should be a 

different size with detents at each position and hard stops, and knobs should be resistant to accidental 

turning. NFPA 1802 also calls for adherence to maintenance and service information, improved voice 

intelligibility, ruggedized testing for high temperature survivability that includes remote speaker 

microphones and cords, and establishing an intrinsic safety rating. 

Note: Although NIOSH has not investigated an incident involving the channel selector knob, NIOSH has 

been informed by fire department personnel that this issue can occur with the channel selector knob as 

well. 

Find NIOSH products and get answers to workplace 

safety and health questions:

1-800-CDC-INFO (1-800-232-4636) | TTY: 1-888-232-6348

CDC/NIOSH INFO: cdc.gov/info | cdc.gov/niosh

FFFIPP: cdc.gov/niosh/fire/

DHHS (NIOSH) Publication No. 2021-117

DOI Number: https://doi.org/10.26616/NIOSHPUB2021117

Page 2

Scan here for more information on FFFIPP