How Things Work: Ejection Seats
- By Mary Collins
- Air & Space magazine, July 2002
(Page 2 of 2)
At low altitudes a pilot doesn’t need to free-fall, so the main parachute opens immediately and the drogue stays in its case. All of the decisions based on speed, altitude, and the weight of the passenger are already made for the pilot before he even clears the aircraft.
Manufacturers have spent decades perfecting all the steps necessary for a fully automated ejection. A hole blows open overhead. The wind surges in. The pilot can feel the chemical cartridge ignite under his seat, which activates a catapult that pushes his seat up a rail. One-tenth of a second after yanking the handle, he’s out of there. As he clears the airplane a rocket system called STAPAC kicks in. The wind wants to flip the seat around like a milkweed seed, but the thrust from STAPAC offsets the rotation and keeps the seat and pilot upright and forward facing.
About two seconds after the seat is rocketed upward, the parachute opens, and that triggers a bell crank that pulls the pins on the seat belts so the seat falls clear of the pilot. After all the bang and rush, the airman drifts quietly for three or four seconds. Then a survival kit drops on a 25-foot line. Upon contact with the water, the kits’ raft and life vest automatically inflate.
While the success rate for ejections has improved dramatically since the 1940s, from about 50 percent to approximately 90 percent today, flailing limbs can get torn off by 600 mph winds, and ejection delays often shorten descents, and that increases the riskiness of the parachute landings. Women pilots, who weigh on average 50 pounds less than their male counterparts, are especially at risk because the lighter the object, the faster the toss and the greater the oscillation.
But even in the most extreme conditions, if a pilot doesn’t wait too long, the ACES II can usually pull off a save. When Captain Jon Counsell had to eject from an F-15C on a training run over the Gulf of Mexico in 1995, he was going Mach 1.4, beyond the accepted parameters for success on the ACES II, which draws the line at 600 knots (690 mph). His limbs flailed so violently during the ejection that he broke his left arm, fractured his left leg in five places and dislocated both knees. Doctors thought he’d never walk again, but seven years later he’s back in the cockpit. In an exchange with the Navy, he now flies F/A-18s.
“I had to make one decision—to pull the handle,” he says. “After that, 13 automatic functions had to work perfectly for me to live, and they did.”