cargo fire

[westinghouse]

hi all,

supposing your in cruise and your experience a cargo fire. (your nearest airfield is 300 nm away)
the bottles discharge but you have no way of knowing if the fire is out.
is there any benifit of doing an emergency descent to FL100?
or could you maintain your level till your close to the nearest airfield and then descend?

[SNS3Guppy]

That really depends what you hope to accomplish. At altitude a cargo compartment that is depressurized and starved of oxygen may stop burning on it's own. If you've already discharged your agent and have a reason to believe the fire is not out, it may be your only option.

Conversely, if you have no landing fields available and have no choice but to travel an additional 300 miles, then is it better to do so at altitude with a higher groundspeed and lower fuel burn, or to descend where the air is thicker, more oxygen is available to feed the fire, fuel burn increases dramatically, and the time to the destination will be longer?

Is the cabin filled with smoke? Do you have an environmental issue requiring a descent due to oxygen limitations? Do you have a nearer alternate for which descent now is appropriate? What sort of terrain and weather is beneath you? What is your fuel state?

All important considerations in determining what you'll do.

[Intruder]

What does your checklist say?!? Likely it says to go to 25,000' so there is less oxygen to support a fire.

[Bullethead]

G'day Westinghouse,

In the airliners I have flown, all Boeings, the cargo compartment fire extinguishing system initially has a high volume discharge of extinguishant then a metered flow usually for around 195 minutes.

The fire detection systems in these aircraft don't detect fire or heat they detect a reduction in the cargo hold visibility, that is smoke, so if the smoke clears then there should be no more fire warning or fire for that matter.

Other events however can cause a false alarm such as happened to me en-route from BKK to LHR in a B747-400 years ago. The alarm went off and the checklist was carried out but the alarm kept going off repeatedly. We diverted to ARN (Stockholm) and did a precautionary disembarkation. The cause of the alarm was a pallet of fruit in the forward hold giving off ethylene gas which was warm and condensed in the cold conditions of the hold and set off the alarm. Ripening fruit gives of volumes of ethylene and some carriers refuse to carry fruit for the above reason.

Regards,
BH.

[westinghouse]

than guys. appreciate the replies.

as per the airbus checklist for a cargo fire there isnt anything said abt descending to a lower altitude.
the only level montioned is FL100 and that for the smoke removal procedure.

[SNS3Guppy]

What does your checklist say?!? Likely it says to go to 25,000' so there is less oxygen to support a fire.


Not everything is in the checklist. Ours ends with "land as soon as practicable." Beyond that, it's time for pilot decision making.