There are mysterious aspects to the loss of the Helios Airways Boeing 737 last weekend, but the fact is that if the depressurisation emergency procedure is not followed rapidly and efficiently then things can quickly go wrong. At least two reports of earlier incidents show just what can happen.
In this 1998 incident the highly experienced captain of a UK-registered Boeing 737 lost consciousness at 35,000ft when his oxygen mask became entangled with his spectacles as he tried to put it on following a suddent depressurisation. A flight attendant who tried to help him also collapsed. Only the first officer remained conscious. Investigators found that a 17 year-old fatigue crack finally led to the failure of a cargo door at altitude.
And in this 1996 incident the captain of a Boeing 727 in the USA collapsed at 33,000ft when he delayed putting on his mask while manipulating the controls to cure a pressurisation problem probably caused by human-error in using the system. Again in this case a flight attendant collapsed in the cockpit and so did the flight engineer who fell across the central console. Once more only the first officer remained conscious.
In both cases the cabin emergency oxygen systems for passengers worked pretty as much as advertised.
But masks can be donned very quickly, as this movie produced by emergency equipment manufacturer Avox-Eros, which equips some 737s, illustrates.