Digital Trunking and Fireground

[tbendick]

The discussion has come up over and over about using a digital trunked radio system for fireground operations.  For someone reason people think this is a good idea.  Here are some facts from a LODD fire that had fireground operations on such a system.

Radio user would receive a ?Bonk? signal is when the Talk Group is busy. This ?Bonk? signal is considered a ?Transmission ?Bonk?
First sixty (60) minutes 579 bonks
Pre  collapse 83
Post collapse/mayday  496
*This does not include "Bonks" from unable to access system (Out of Range)

Digital Delay is a period of time (usually 1 to 1.5 seconds) that occurs after a radio user speaks and the message is sent through the digital system and heard on another radio. This delay leads to multiple personnel trying to use the radio at the same time and produces a large amount of ?Transmission Bonks?.

A ?Quick Key? occurs when a radio mic is engaged for any length of time ? of a second or less. These usually occur when the user accidentally touches or bumps the Push-to-Talk button (PTT) on their radio. When a ?Quick Key? occurs, it captures the Talk Group for 3-4 seconds.

During the first 60 minutes, there were approximately 96 ?Quick Keys? which totaled 6 minutes and 24 seconds of possible unusable talk time. This equates to approximately 11% loss of air time in the first hour. These 96 "Quick Keys" also led to
111 transmissions ?Bonks? which is also estimated to be 19% of the total transmission ?Bonks? that occurred at this fire.

It was further learned that some of these ?Quick Keys? were the result of members in the department that weren?t assigned to the incident. Members across the city had turned on their radios to listen to the incident and at some point, accidentally created a ?Quick Key?

 

[FD347]

Anyone who thinks digital fireground, be it trunked or conventional, can work needs their head examined. There is enough evidence from the last fiasco that it didn't work then, and can't work ever the way we work a fireground.

 

[336]

tbendick, can you post the link for the complete NIOSH report, please?

Monroe County is allegedly changing over to this crap "by 2016".  PD made the change a few years ago and a majority of them dislike it, for the same reasons..

 

[BCR]

Usually new technology is a good thing helping to progress a department toward more streamlined communications with fewer dead spots etc.. In this case progression is a bad thing that sends a department backwards toward the stone age with an expensive price tag. Let the statistics speak for themselves, this system is NOT Fire friendly

 

[Bulldog]

There has been so much documentation showing problems like those shown here I don't understand how any department would even consider going to a complete digital trunked system!  Digital trunking may be all right for dispatch and noncritical communications but fire ground definitely needs to be analog non-trunking!  I'm not really in tune with the PD side but I'm sure the same problems exist there on the scene of major incidents such as when SWAT is involved.

 

[Firebuff66]

I work for a Motorola shop and I would agree the only thing on fire ground should be Simplex. Using a trunking system or repeater system for fire ground is inviting disaster. We have 100s of NIOSH reports showing that fact.

As for the digital/analog debate you can't look at the FDNY issues of the late 90s anymore, digital is totally different now and so are the radios.  Many groups are doing research on this issue and every time they come out with issues the Vendors change the radios to conform, Motorola has already changed the APX to address the Quick key issue. We have 10 departments using digital fire ground in simplex and have no issues and love the noise reduction of the new radios.

So going back to Houston, The digital "delay" would be fixed by being on simplex, the system "bonks" would be fixed by being on simplex and the quick key would be fixed by being on simplex.

As for digital voice and fire ground operations, that debate will go on for 20 or 30 more years im sure

 

[Ladder68]

Sorry for finding this topic late but everything tbendick has said happened at this incident did in fact occur at this incident as it relates to our "new" radio system. We were 1st truck on the box for the SW Inn Fire and lost Fire Fighter Robert Garner and Fire Fighter Anne Sullivan from our Engine Co. and Captain Bill Dowling permanently disabled. While the radios did NOT cause their loss, they did hamper rescue efforts as the incident escalated following the transmission of the initial May Day.

From the inception of the digital system we had issues regarding the quick key, the weaker signal strength and other issues. The Department was very proactive with training of the new system and everyone had the training at least once. The problem, as it appears still, is that the system was said to do X and really only does Y. A year and a half after this fire and our system has had the "quick key" removed and other updates done but to no avail. Just 2-tours ago in a 3-11 fire I couldn't talk to the Division Officer who was giving me direction for ladder pipe ops and he was 50' from me. I could hear him, but couldn't talk to him. Next transmission I could talk but not hear him although the radio of the FF next to me on the turntable was able to relieve him. Suffice it to say it is not fixed and the Departmrnt has developed a form for when this occurs. Every day now we are doing extensive daily testing, city wide mind you, of all riding positions on all talk groups. While we are not the size of FDNY, to have 86 Engines, 37 trucks/towers, 3 rescues and 21 District Chiefs plus Haz Mat, ARFF, and not to mention EMS units, doing this is quite the daily task.

There are a lot of theories on how this happened and what needs to be done to fix it, but bottom line when you get down to it money will be needed and someone will have to own up to their being a problem. There are documented cases where fire fighters were lost and due to their digit radio system, unable to call for help. Colerain Township, Ohio comes to mind. In our case we hope it's worked out before the system is a contributing factor to an injury or worse.

 

[Firebuff66]

Both tbendick and Ladder 68 say the issue in the posts. Fire ground should never ever be on a talk group of the system. I work on 2 Motorola Digital trunk systems and the FDs have no issues on the fire ground at all, The reason is that they are on simplex on the fire ground and a repeater links them back to the trunk system. FDNY is doing the exact same thing now, the simplex fire ground is rebroadcast over the digital trunk system.  its simple and tested and works great.  Its sad that people died and got hurt when the solution has been being used for 6 years here with no issues