TOUGHENING UP

Passengers in plane crashes today, such as the one in San Francisco involving Asiana Airlines Flight 214, are more likely to survive than in past disasters. Advances in aviation technology have made these feats of survival possible, including:

Stronger seats. Today’s aircraft seats – and the bolts holding them into the floor – are designed to withstand forces up to 16 times that of gravity.

Fire retardant materials. Carpeting and seat cushions are now made of materials that burn slower, spread flames slower and don’t give off noxious and dangerous gases.

Improved exits. Doors on planes are much simpler to open and easily swing out of the way, allowing passengers to exit quickly.

Better training. Flight attendants at many airlines now train in full-size models of planes that fill with smoke during crash simulations.

Stronger planes. Aircraft engineers have looked at structural weaknesses from past crashes and reinforced those sections of the plane. AP

Three seconds later, the aircraft’s stick shaker – a piece of safety equipment that warns pilots of an impending stall – went off.

The normal response to a stall warning is to boost speed. Hersman said the throttles were fired and the engines appeared to respond normally.

At 1.5 seconds before impact, there was a call from crew members to abort the landing.

The details confirmed what survivors and other witnesses said they saw: an aircraft that seemed to be flying too slowly just before its tail apparently clipped a seawall at the end of the runway and the nose slammed down.

Pilots normally try to land at the target speed, in this case 137 knots, plus an additional five more knots, said Bob Coffman, an American Airlines captain who has flown 777s. He said the briefing raised an important question: ‘‘Why was the plane going so slow?’’

The plane’s Pratt & Whitney engines were on idle and the pilots were flying under visual flight rules, Hersman said. Under visual flight procedures in the Boeing 777, a wide-body jet, the autopilot would typically have been turned off while the automatic throttle, which regulates speed, would have been on until the plane had descended to 500 feet in altitude, Coffman said. At that point, pilots would normally check their airspeed before switching off the autothrottle to continue a ‘‘hand fly’’ approach.

There was no indication in the discussions between the pilots and the