IF AN aircraft depressurises, pilots should don oxygen masks immediately. So
say air safety experts, who add that studies dating back to the Second World War
may have led pilots to overestimate how long they have to react.
The US National Transportation Safety Board says pilots may have only
seconds, not minutes, before they become too disoriented to function. The advice
follows the NTSB鈥檚 investigation into the crash of golfer Payne Stewart鈥檚
Learjet in October 1999, after it flew without a pilot for four hours and failed
to respond to radio calls. The crew and passengers lost consciousness after the
cabin depressurised. All six were killed.
Although it鈥檚 not clear why the jet鈥檚 pilots didn鈥檛 get supplemental oxygen,
the NTSB found that many pilots have an unrealistic idea of how much 鈥渢ime of
useful consciousness鈥� they have. Previous studies, some dating back to the
1940s, have suggested pilots can function for a minute or two in a depressurised
cabin at about 30,000 feet. But NTSB medical officer Mitch Garber says recent
studies show pilots might have as little as eight seconds. Earlier studies
measured the ability to continue counting backwards from 1000. 鈥淏ut that doesn鈥檛
relate to the ability to take appropriate emergency action,鈥� he says.
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