I enjoyed reading valuable insights and viewing wonderful pictures of jets for several years on a.net as an observer. Finally decided to join. Thanks for keeping the shop open and the lights on until lazy "foot draggers" like me act and join
a) True, rapid decompression gives more observable signs (sudden drop in temp, fog/mist suddely filling the cabin, could be preceded or accompanied with loud noises). However, untrained individuals are not likely to recognize that these signs indicate "Rapid Decompression". This is why above a certain flight level one of the two pilots HAS TO
go on Oxygen above that flight level (period), even with both pilots at the controls.
b) Slow cabin depressurization to cruise level altitudes is practically impossible to detect by a single individual without instrumented alarms. When both pilots are at the controls and the flight level is not that high, it is supposed that if one of them passes out or become sluggish (usually silly with sheepish smile and unresponsive to verbal ques), then the other (well trained professional) pilot would figure out it is hypoxia before he passes out to and dons his oxygen mask. If one pilot leaves his position for any reason the second pilot should be thinking (if I start to feel silly or light headed - I am going on Oxygen right away) that hypoxia may become a factor and watch out for that. With one pilot out of the cockpit some pilots [at least some pilots I flew with] just go on Oxygen even if it is not dictated by the regs (period). Sometimes the cockpit would have a third relief pilot and they may not go on Oxygen if it was NOT in the regs.
No one knows what happened on MH370. But bear with me here as I go out of my way to show that not all possibilities are entertained yet. Easy on the Captain, not everything in life is fully sinister you know
1. MH370 levels off at initial cursing altitude following a good take of by FO under the supervision of the Captain. Captain tells FO "Well done I have the airplane". FO says "Thanks, I will go get us Coffe". Captain goes on the radio and says the "good night" phrase to ATC. FO gets out of his seat and opens the door to the Cabin.
2. Someone waiting outside (pretending to be waiting for the bathroom) pushes the door all the way in, enters the flight deck and points a gun to the Captain's head. "Turn off the transponder and the radios!" and locks the door behind him. The captain does what he is told.
2a. FO wanting to be a hero fights with the intruder who shoots at the center console (now radios are inop!). He shoots the captain in the head once or twice and then shoots at the FO. FO continues to fight and manages to get the intruder shot too (either with the intruder's gun or with a weapon that MH
security procedure could have called for that "one of the two pilots on deck will carry a weapon on international flights" (anyone heard about the US "Armed Pilot" Program?"
2b. Intruder tells the FO to go back to his right seat and locks the cockpit door. Intruder starts shooting them both from behind. One of the two pilots although shot manages to get the intruder shot too (source of weapon same as 2a).
3. With one pilot dead and the other pilot unconscious MH370 does the climb, 270 degree turn, and descend unexplained maneuvers.
4. The unconscious pilot partly recovers and tries his best (aviate, navigate, communicate). His first priority is to avoid terrain. He sets MSA as the minimum alt in the AP. Shot in the head and thought to be dead by the intruder the Captain with compromised vision and other injuries while passing in and out of consciousness due to bleeding tried his best. He puts the way-point to the north followed by a vector to the south then passes out one last time and dies. This or a similar scenario can happen.
A.netters, are you sorry I joined a.net or what? [Edited correcting typos 2014-04-10 10:41:37]
[Edited 2014-04-10 10:42:56]