操縦室だけ独立した気圧・酸素圧制御になっているのか。

このところ定着した格安航空会社いろいろあるが、そのひとつ、ヘリオス航空機が墜落。お気の毒な話。問題の多い航空会社ながら、実に謎な墜落直前の様子。

　同機は、キプロスのラルナカを出発し、アテネ経由でプラハに向かう途中だった。ＡＰ通信などによると、緊急発進したギリシャ空軍機からの情報として、飛行中の操縦席に機長が見えず、副操縦士は席にうずくまって動かず、操縦役が不在の状態だった。２人が折り重なるように倒れていたとの情報もある。
朝日 05年8月14日付

ＡＦＰ通信などによると、ギリシャ国防省は航空機内の酸素供給が途絶えたか気圧が低下し、機長と副機長が意識を失ったとみている。
毎日　05年8月14日付

ガーディアンにもう少し詳しい。

Two Greek air force F-16 fighter jets were scrambled when the Cypriot plane lost contact with air traffic controllers in Athens. Their pilots reported that the plane's captain was absent from the cockpit, and the co-pilot was slumped over the controls.

A government spokesman, Theodoros Roussopoulos, said the F-16 pilots reported that oxygen masks could be seen hanging from the cabin ceiling. When the pilots flew by the plane a second time, he said, they saw two people apparently trying to take control of the Boeing-737, but it was unclear if they were members of the crew or passengers.

Greek television reported that early in the flight the airliner's crew had told air traffic control that there were problems with the air conditioning.
ガーディアン　05年8月15日付

しかしながら、

"The pilot has turned blue in the face," one passenger said in an SMS message to a cousin before the crash, Greek television reported.
"Cousin, farewell, we are freezing," the text message said.

ということは、操縦室だけで気圧ないし酸素がひどく途絶えた、ということになる。ありえるのだろうか。

・・・
さらにもう少し詳しい解説発見。

Chris Yates, an aviation analyst with the journal Jane's Transport, said there seemed to have been "some form of depressurisation" of the aircraft cabin before yesterday's crash.

He said: "It would have to have happened in a split second, otherwise the pilot and co-pilot would have got themselves oxygen straight away and brought the aircraft down to a safe altitude where they could breathe." The pilot of one of two fighter jets scrambled after air traffic controllers in Athens lost contact with the flight said he could not see the captain in the cockpit, while the co-pilot appeared to be slumped at the controls.

"That suggests things happened so rapidly that neither the pilot nor co-pilot had time to get oxygen," said Mr Yates.

He expressed surprise that passengers had been able to send text messages at a time when the crew appeared to have been incapacitated. "If it was immediate depressurisation, then everyone would have been affected."

Kieran Daly, editor of Air Transport Intelligence, said the cause was a puzzle. "There are very good procedures in place for dealing with a lack of oxygen. There are so many warning systems: the crew should have been aware there was a problem," he said. Under normal circumstances, a sudden loss of cabin pressure would trigger the automatic release of oxygen masks over passengers' heads. The pilots would then aim to take the plane down to an altitude of 10,000 feet as quickly as possible.

On-board canisters carry oxygen for use during emergency loss of cabin pressure, but if masks failed to deploy, the crew and passengers would eventually suffocate. At 30,000 feet, most would lapse into unconsciousness after five minutes and be likely to die from asphyxiation within 20.
ガーディアン　同日付

結局

Daniel Holtgen, of the European Aviation Safety Agency, based in Cologne, said: "It is highly unlikely the loss of pressure alone would cause such an incident. There would have to be other contributing factors."