The failure caused the cabin to lose pressure instantly and the oxygen masks to deploy.

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Oxygen masks were not deployed, indicating that the cabin did not depressurize, the bureau said in a 2009 report.

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But eventually, when the passenger oxygen masks dropped as the plane steepened its descent, the news had to be announced.

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It was Mstislav who had the foresight to seal the Den remotely, then insist that we don oxygen masks and investigate.

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Of course, they are also wearing oxygen masks - more tightly fitted than those of the passengers, to keep out fumes and smoke.

BBC: What to do when planes lose pressure

The cabin isn't pressurized, so pilots had to wear oxygen masks.

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And instead of moving with urgency the Trojans dallied as the clock ticked, like browsing SkyMall magazine as a plane's oxygen masks drop from the ceiling.

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No need for the oxygen masks!

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While this is happening, the passengers will be provided with oxygen from drop-down masks which will give them oxygen for 12 to 15 minutes, by which time the aircraft should be at a lower level.

BBC: NEWS | Europe | Dangers of aircraft decompression

It seems that their efforts might not stop at masks and underwear with bringing oxygen on board considered for future events.

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If this alert is received, the pilots should put on masks which will provide them with oxygen while they rapidly descend the aircraft to an altitude where the occupants can breathe without assistance.

BBC: NEWS | Europe | Dangers of aircraft decompression