Has anyone any information on an aircraft fire where the crew descended to 25,000 unpressurized and what the results were? How about manufacturer or government testing regarding fire suppression at 25,000 pressure altitude?
When descending to FL250 and following the cargo fire procedure, how long does it take to get the cabin pressure to 25,000? Someone posted that the 747 depressurizes at 2500 fpm. Is that correct? Is that the same for all the Boeings? Other manufacturers? Is it advisable or even possible to hurry that up manually? What would be the physiological effects of doing that? Someone posted a USAF study whereas 25,000 was chosen to lesson the chances of decompression sickness. What can we expect as to the possibilities of continued fire at 25,000 cabin altitude? What can we expect at 25,000 physiologically? Will a pack at 1/2 flow keep the cockpit warm? Is pressure breathing required? Et cetera...
I don't know what will happen with the lithium batteries at 25,000 feet. Besides the lack of oxygen, it should get pretty cold back there. If they do continue to burn, hopefully the stuff around them will not and the batteries may eventually burn out. Sound reasonable?
When at cruise at about 5-6,000 cabin altitude, if a major fire develops and an immediate descent is made, will the cabin altitude ever rise to a "fire extinguishing" level? Is it possible and should it be considered to put the fire out at 25,000 unpressurized before descending?
Sorry for the shotgun approach with the questions, but there seems to be a lack of information on a lot of this stuff.
As for the specifics of UPS 6, I'm waiting to learn the flight profile after discovering the smoke. What was the cabin altitude profile during this return? Did the cabin ever get depressurized sufficiently to impede the fire? When did the smoke become so dense as to partially or completely obscure vision both inside and out, both in terms of flight profile and time since discovery?
Last edited by F111UPS767; 12th Oct 2010 at 18:01.