SAN FRANCISCO (AP) — A federal safety official said yesterday that the cockpit voice recorder from Asiana Flight 214 showed the jetliner received a warning that it could stall because it was flying too slowly and tried to increase its speed before it crashed.
National Transportation Safety Board chief Deborah Hersman said at a news conference yesterday that the recorder also showed the Boeing 777’s crew called to abort the landing about 1.5 seconds before impact.
National Transportation Safety Board chief Deborah Hersman, at a briefing on the crash, said that the plane was traveling at speeds well below the target landing speed of 137 knots per hour, or 157 mph.
“We’re not talking about a few knots,” she said.
Hersman also said the aircraft’s stick shaker — a piece of safety equipment that warns pilots of an impending stall — went off moments before the crash. The normal response to a stall warning is to increase speed to recover control.
There was an increase in speed several seconds before the crash, she said, basing her comments on an evaluation of the cockpit voice recorder and flight data recorder. They contain hundreds of different types of information on what was happening to the plane.
And at 1.5 seconds before impact, there was a call for an aborted landing, she said.
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 raises an important question: “Why was the plane going so slow?”
The plane’s Pratt and Whitney engines were on idle, Hersman said. But the normal procedure in the Boeing 777, a wide-body jet, would be to use the autopilot and the throttle to provide power to the engine all the way through to landing, Coffman said.