Loss Of Pressurization At High Altitude
Hi,
I get some questions regarding the loss of pressurization (not sudden decompression) at HIGH ALTITUDE due to all engines flame-out (even the APU will not be able to provide air unless at low altitude):
1-So during depressurization how long the oxygen will be available for the passengers from cruise altitude (modern aircrafts are flying above 40000ft, for certain aircraft like 747 the max certified ceiling is 45100 ft) to a safe altitude? We suppose the aircraft have a normal air leakage rate.
A safe altitude will be 14000 or 10000 ft?
Will the quantity of oxygen be enough for passengers?
2-In such case, I guess the crew will perform emergency descent: how long it take to reach a safe altitude?
Will pilots try to restart engines during the emergency descent?
Can the attempt to restart engines affect the emergengy descent (the rate of descent)?
3-From a safe altitude to the landing, how air is provided to passengers and crew? We suppose engines and APU still off.
4- How air is provided for the flight crew during an unpressurized ferry flight and without oxygen? (engines operating of course).
5-And finally the last question: the aft outflow valve in the 737-NG is thrust recovery??? does it mean that the valve is providing thrust by taking advantage of the difference of air pressure between the pressurized zone in the aircraft and the ambient air??? or it means other thing. By the way this valve is fitted with 2 gates: aft gate and forward gate.
Your feedback will be very appreciated. Thank you in advance.
Best regards.
P.S: I guess the problem will be worst in case of rapid decompression at high altitudes (40000 ft or above) since the oxygen masks (even pilots masks I guess are not pressure feeded O2) are not supplied with "forced" oxygen.