Experts point to takeoff and turbulence as the most worrisome moments for passengers.
Tom Bunn, a retired airline captain and licensed therapist, is the author of "SOAR, The Breakthrough Treatment for Fear of Flying." He cites 10 rapid-fire events that cause stress hormones to go bananas -- one after another -- shortly after the plane's door closes:
The engines rev for takeoff and the exhaust thunders. The acceleration of the plane pushes you back, recalling feelings of a physical intrusion, like bullying -- or much worse. The plane bumps as it rolls down the runway. The aircraft feels "flimsy" because the overhead compartments shake. The nose rises, and the plane lifts off, making you feel heavy in your seat. The landing gear noisily retracts.
"Ten seconds later," Bunn said, "engines slow and the nose is lowered for 'noise abatement' which causes passengers to believe the engines have quit and the plane is falling."
Passengers white-knuckle their way through the process, which Bunn points out is over in just about 2 minutes.