View Full Version : Cargo Fire Detection system

24th Oct 2005, 19:28
Does anyone know of any fire detection system for belly cargo or cargo aircraft that uses a camera and UV or another means?

If so, if this system is installed does it allow for non diversion if the pilot can tell the alarm is false and there is no fire?

Thanks in advance. :)

prop jocket
27th Oct 2005, 19:18
There are only two types of detector certified for class C freight holds ( as fitted to 747's and the like ). The detectors are either particulate or ionising, each having advantages and disadvantages.

Particulate detectors rely on detecting the sooty particles produced by combustion, which means that they won't detect anything until the fire is actually taking hold. However, they also don't trigger fire warnings if you're carrying bananas like the ionising ones seem to do for some reason.

Ionising detectors don't need the fire to be established before they trigger a warning, but as I said above they are prone to false alarms.

You pays your money and takes your choice.

An American company ( nameless to protect the guilty) tried to market a wireless conversion for the 737's to go from D to C class holds. Their system used infra red detection. Great bit of kit - sweaty baggage loaders set it off, and on one occasion a genuine fire was raging and the wireless system triggered the alarm in the aircraft that was on stand beside it, without a peep from the cockpit module on the one that was blazing away.

Hope this helps.

27th Oct 2005, 20:03
Thanks much for the info.

What is the difference between a class C and class D cargo hold?

I wonder what a wired infra red system would be any good?

Do you think pilots would be confident that there was a false alarm if they had cameras to let them see the belly so then not divert?

I suppose it could also allow them to make a ditch decision of the fire is raging away and they better land in the next 5 minutes or they will lose control and crash.

27th Oct 2005, 21:15
As far as I know, no aeroplane fire detection system allows any discretion not to make an emergency landing. I think few people would be happy continuing with a warning occuring. BA had a 747 fly for an hour with a cargo fire warning to get to Santa Maria in the Azores for a landing in a gale and a full emergency evacuation was carried out without delay. Should a fire have burst through the cabin floor, it would have been too late to then order an evacuation without fatalities, so it was an absolutely spot on decision. That made fascinating watching of the digital film from someone's movie camera during the incident, and the wind was very obvious.

Cargo holds on larger aeroplanes contain large metal baggage containers almost completely filling the volume. I don't see how a camera could film the range needed to adequately ensure all areas are clear when the fire may be located behind baggage or containers and the smoke blown towards the exhaust without being observable. I'm not sure if there are types of fire that produce fewer particles or smoke that may be undetected visually or by the smoke detectors. Ignore at your peril (and 400 other peoples' peril!)

27th Oct 2005, 21:45
This company produces an optical cargo smoke/fire detection system:


(This is a British company as far as I know :} )

prop jocket
1st Nov 2005, 19:25
747focal: The compartments on aircraft are categorised as A through D.

A class A compartment is one that the crew will access as part of their normal duties ( toilets for example ). Hand held extinguishers are easy to bring to bear.

A class B compartment is one to which the crew have access, but wouldn't normally go there without good reason ( EG lower 41 on a jumbo ). Again, hand held extinguishers can easily be brought to bear.

A class C compartment is one to which the crew don't have access in flight ( an exception to this is the fwd cargo on a 747 which is classified as a class C compartment, but you can get to it through the lower 41 if you must ) and has both fire suppression and detection; there are sub classifications of class C dependent upon the certified duration of suppression.

A class D compartment has no in flight access, and either detection but no suppression or neither detection nor suppression; fire protection being provided by the flame proof linings and the ( theoretically ) near air tight nature of the compartment.

There's a bit more to it than this, but hope this helps.

2nd Nov 2005, 00:47
For additional info:
With respect to immediate diversion and landing, on ETOPS aircraft the Class C compartment fire suppression must be able to suppress a fire for the full duration of the ETOPS rating (which may be as much as 180 minutes) plus an extra 15 minutes. This means installing larger capacity fire extinguishers with a multiple shot capability. The first shot is fired when the fire detection sounds the alarm and further shots at specific intervals as the diversion progresses.

2nd Nov 2005, 22:29
747F this does appear to something that Airbus have looked into previously. No idea if they ditched the idea or have been following up on it though.

Fire verification system (http://www.fire.tc.faa.gov/pdf/systems/CargoFireVerification.pdf)