A quiet flight is transformed in an instant into a bone-cold chaos of shrieking wind, flying debris and crushing G forces as the pilot dives to save the plane.
If you think the flight crew will come and take care of you, think again.
The tragedy of United Airlines Flight 811 was only the most recent in a series of episodes of sudden decompression in jetliners at high altitude.
“People aren’t really aware of the physiological phenomenon of rapid or explosive decompression,” said Barbara Hansen, whose El Segundo company, In-Flight Safety Services Inc., trains flight attendants to handle emergencies and business travelers--the most frequent fliers--how to increase their chances of surviving such incidents.
“Passengers have more control (over their fate) than they think they do,” Hansen said. “They just need to become more aware.”
Hard to Respond
Passengers need to think in advance “what they would do in a rapid decompression” because if it happens, “people get disoriented. They can’t react.”
“They think they can just sit there and (flight attendants) are coming to help them. But (the attendants) need to be secured in their seats during the rapid descent.”
Some of the 336 passengers and 18 crew members on Flight 811 said they heard a hissing moments before a 10-by-40-foot hole opened up behind the cockpit and nine passengers were pulled out of the plane to their deaths more than 20,000 feet below.
Hansen said the hissing should have warned passengers that the nightmare of a rapid or explosive decompression was beginning.
Once pressure is lost, the inside temperature plunges to that outside, typically well below zero. The sudden temperature change causes rapid condensation that produces fog.
The fog, combined with the enormous noise of wind tearing through an open fuselage, makes communication virtually impossible.
Depending on the altitude, passengers may have little more than 15 seconds to find and affix their oxygen masks before they pass out.
The masks, designed to drop automatically during a pressure loss, often do not.
“Nicotine, dirt and grime gets up there (in the mask compartment hatches), so when we finally need them, they stick,” Hansen said.
She recommends asking a flight attendant before takeoff how to manually open the oxygen mask compartments.
Passengers also should make sure that their seat belts are fastened at all times and pulled “uncomfortably tight” once the emergency has begun.
The normal procedure in a sudden decompression is for the pilot to go into a steep dive to deadly cold and lack of oxygen. Any unbelted passengers face the risk of being thrown about the cabin--or out of it.
The steep dive will produce G forces that will shove the body back into the seat, adding to the discomfort to the joints and sinuses from the sudden pressure change.
Once on the ground or in the water, the prepared passenger--having checked out where every door is located, not just the one closest to his seat--should get out as fast as possible.
Hansen said videotape of the disfigured 747 on the ground in Honolulu also showed what she called a persistent problem when passengers evacuate.
“I saw the universal problem (of) everyone taking their carry-on luggage with them,” she said.
Hansen said luggage and other property can puncture inflatable escape chutes and cause dangerous clogging of the aisles and at the bottom of the slides.
Emphatically, she advises passengers to “leave everything. If it’s that important, have it on your person.”
Hansen became a flight attendant for TWA 20 years ago. She later trained attendants for several airlines before becoming a consultant and training the cabin attendants for corporate and government jets.
In 1987 she started offering passenger survival courses to corporate frequent flyers.