On January 25, 2011 Shaker Heights Fire Department units along with units from Cleveland Heights, South Euclid and Beachwood were operating at the Chelsea Apartments, 3330 Warrensville Center Road Apartment, for a working kitchen fire. The fire was in apartment 508 on the fifth floor.
The initial unit on scene, Engine 216, reported that they had a grease fire that had extended into the cupboards above. They had heavy smoke with a little heat or fire. E216 reported that a sprinkler had activated above the fire which had kept the fire confined to that area.
Captain Zugan was Incident commander and located at street level in front of the building at the rear of his vehicle (C263). Captain Zugan reported that during the overhaul stage, for a period of 2-3 minutes, he noticed there was a problem communicating on the Channel 2 – Fireground (Zone 29 Eastcom – Channel 2). During this time no one on the fireground was able to communicate. Captain Zugan reported hearing only interference noises like buzzing and clicking. Capt. Zugan observed different radio ID’s appearing on the MARCS radio in the rear of C263 but was unable to hear any voice communication.
Inside the building, Lt. Sepesy was operating directly under a flowing sprinkler head. He also heard the interference. He turned his radio off and then back on at which time the interference immediately stopped. Lt. Sepesy reports that his radio was totally soaked from operating under the sprinkler. Lt. Sepesy reporting hearing the transmit tone sounding on his radio.
Fireground communications then became fully operational again and there was no further issue throughout the incident.
Analysis / Discussion:
After reading the complaint forwarded by Capt. Zugan (Exhibit A attached). Lt. Sepesy’s radio was obtained and held in quarantine. We secured his radio in the state it was given to us. We examined it visually only without altering it. It is a Motorola XTS 5000R with a model NMN6193C remote speaker microphone attached.
SHFD Portable Radio ID #: 6178 | |
Model ID: | XTS5000R |
Description: | XTS5000 MDL II Portable 700/800 |
Serial #: | 721CHF6178 |
Model # : | H18UCF9PW6AN |
Remote Speaker Microphone Model #: | NMN6193C |
Remote Speaker Microphone Serial #: | N/A |
We inquired into the water proof characteristics of this radio and speaker/mike combination. We found that the radio meets military specs and is submersible. The remote speaker/microphone is rated water resistant only.
The team investigated the condition of the cross band repeater on C263 to see if it could have played a part in the interference. The cross band repeater on C263 was found to be off. This cross band repeater only operates between two radios, one in the VHF band, and the other in the UHF band. If the repeater had been activated during the incident it would not have effected the operations on fireground channel 2 (770.1625 Mhz.).
We investigated whether any mutual aid companies had any radio equipment activated while they were on scene. No other communities had active repeaters that would have interfered with the operations on fireground channel 2 (770.1625 Mhz.).
There are two 700/800 MHz MARCS radios in the back of C263. They were both found to be in working order.
We conducted a test of a speaker/microphone of the same model number with water to see if we could cause it to fail. Attaching it to the same model radio, we immersed the head of the speaker/microphone in water and sprayed it with a garden hose. After approximately ten minutes the radio began transmitting intermittently and at some points locked into transmit for longer periods. The surrounding monitoring radios began to buzz and click. To further recreate the situation, additional radios were utilized to recreate other traffic trying to talk on fireground. Radio ID’s were observed on the display of the fireground radio in C263. There was no audio from the other radios simply the ID’s displaying.
The next day the same test was repeated. The results were the same. This time members were present who were on scene of the initial event. Members in attendance agreed that the sounds on the other radios were those that they heard that night. Furthermore Captain Zugan also agreed that the sounds and the ID’s flashing on C263’s radio replicated the conditions of the Chelsea fire scene.
On the second day of testing, another speaker/microphone was tested. The Motorola Remote Speaker Microphone model number PMMN4038A has a 30 minute submersible rating. It is recommended for firefighting use by Motorola. We tested one of these mikes by submersing it for approximately 50 minutes and spraying it directly with a hose. We could not cause it to fail and it worked perfectly at the end of the water test.
The suspect radio and speaker/microphone were sent out to Motorola Solutions for radio examination. We asked Motorola to look the radio and remote speaker microphone for any problems.
The radio was examined and found to be working properly within specifications. There was no sign of water intrusion into the radio. Motorola believes that there was nothing wrong in the radio that would have caused the problem that was encountered.
The remote speaker/microphone was examined by Motorola. They found that there were signs of water intrusion and corrosion inside the remote microphone. They stated that this could have caused a malfunction.
Findings:
Our findings are that the heavy water drenching of a remote speaker/microphone that was water resistant only and not rated for the conditions encountered at this scene caused this communication failure. The drenching caused the microphone to lock into the transmit mode thereby causing interruption of communications on the selected channel.
Recommendations:
- It is recommended that the use of the “Water Resistant-Only” remote speaker/microphone (NMN6193C) be suspended immediately for any radio used for fireground operations or radios that may become wet.
- The alternative replacement speaker/microphone would be at minimum the Motorola PMMN4038A Remote Speaker Microphone. This microphone carries with it a 30 minute submersion rating and is recommended for firefighter use.
- Radios that become wet must be dried at the first opportunity. Remove the battery and dry the inside surfaces of the battery and the radio. Remove the speaker/microphone and dry the connections between the speaker/microphone and the radio.
- Inform all department members of how to tell if their radio may be failing and transmitting by listening for the transmit tone.
- Share this report with other possible users of this radio and speaker/microphone combination.
