With regard to the missing Malaysian airliner, some comment on the topic from an acknowledged aviation authority, more or less copied in entirety.
It now accepted that the missing airliner FLEW FOR FOUR HOURS AFTER HAVING DISAPPEARED FROM RADAR CONTACT. PINGS FROM THE AIRCRAFT ENGINES, AUTOMATED DATA TRANSMISSIONS REGARDING PERFORMANCE RECEIVED AS IF NOTHING WAS AMISS!!
"I've been postulating my own theory, based on prior history of disappearing airplanes."
"There are a few instances where planes at altitude just seemed to fly on without the pilots responding to air controller calls. It became apparent the planes were on auto-pilot and their crews--and passengers--were unconscious or dead. In most cases, the air cooling system malfunctioned, feeding contaminants into the oxygen system (like carbon monoxide from the engines--the cooling systems in my day were always fed off the 17th stage of the compressors in the engines, making it probable that a leak could add some really dangerous fumes, perhaps without anyone noticing). In other cases, the plane gradually depressurized such that the automatic warning systems did not react as the passengers and crew gradually 'fell asleep' from lack of oxygen."
"The planes continued flying, crew less, for hours, until their fuel ran out and they were observed to dive to the sea or ground when the engines flamed out. In those cases, fighter planes were flown alongside the errant airplanes, where the military pilots could see into the cockpits and see everyone apparently 'asleep'--or dead. Nothing could prevent the inevitable end - the fighter crews could only accompany the planes until they crashed. One had a famous golf pro [Payne Stewart] and his entourage, another was a Boeing KC-135 (like the Boeing 707) Air Force refueling tanker."
"The missing Malaysia plane seems to have one of three possibilities":
"2) cockpit contamination or depressurization, as I mentioned"
"3) sudden, catastrophic explosion."
"With the first, it is likely that hijackers would be announcing their goals or, as in 9/11, trying to fly into some significant target to make their political statement. Additionally, virtually every passenger would likely have had cell phones. If the hijackers confiscated them, it is probable that not all would be found immediately, giving a passenger time to get a call or text off--even if out of a reception zone, a text message would 'hold' until a tower was in range, and sent, or so it would seem."
"With the last, there should have been wreckage scattered for a distance, leaving some kind of pattern or trail to be found."
"But with reports now of continued 'pinging' and possible continued flight, the first two options are most likely. And the problems mentioned with item (1) hijack would seem to mitigate against that possibility. So that leaves item 2 as most probable, in my opinion."
Personally, my [Bert] instantaneous reaction was that this was a hijack. Within the context of the recent Uighur knife attack in Kunming and that the preponderance of the airliner passengers were Chinese nationals en route to Beijing this seemed reasonable to me.
The one-two punch.
But now, one can infer further and have second thoughts.
And it is all so strange!! And thank you acknowledged aviation authority.