SAN FRANCISCO — Pilots of Asiana Flight 214 were flying too slowly as they approached San Francisco airport, triggering a warning that the jetliner could stall, and they tried to abort the landing but crashed barely a second later, the head of the National Transportation Safety Board said Sunday. The airline said the pilot at the controls had little experience flying that type of plane.
While federal investigators began piecing together what led to the crash, San Mateo County Coroner Robert Foucrault disclosed that he was looking into the possibility that one of the two teenage passengers who died Saturday actually survived the crash but was run over by a rescue vehicle rushing to aid victims as the plane burst into flames. Remarkably, 305 of 307 passengers survived the crash and more than a third didn’t even require hospitalization. Only a small number were critically injured.
Accident investigators are trying to determine whether pilot error, mechanical problems or something else was to blame for the crash. At a news conference, NTSB chief Deborah Hersman disclosed the Boeing 777 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 described the frantic final seconds of the flight as the pilots struggled to avoid crashing.
Seven seconds before the crash, pilots recognized the need to increase speed, she said, basing her comments on an evaluation of the cockpit voice and flight data recorders that contain hundreds of different types of information on what happened to the plane. 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 and Hersman said the throttles were fired and the engines appeared to respond normally.
At 1.5 seconds before impact, there was a call from the crew 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 raises 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 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, he said.
There was no indication in the discussions between the pilots and the air traffic controllers that there were problems with the aircraft.
The airline said Monday in Seoul that the pilot at the controls had little experience flying that type of plane and was landing one for the first time at that airport.
Asiana spokeswoman Lee Hyomin said that Lee Gang-guk was trying to get used to the 777 during Saturday’s crash landing. She says the pilot had nearly 10,000 hours flying other planes but had only 43 hours on the 777.
Among the questions investigators are trying to answer was what, if any, role the deactivation of a ground-based landing guidance system due to airport construction played in the crash. Such systems help pilots land, especially at airports like San Francisco where fog can make landing challenging. The conditions Saturday were nearly perfect, with sunny skies and light winds.
The flight originated in Shanghai, China, stopped over in Seoul, South Korea, before making the nearly 11-hour trip to San Francisco. The South Korea-based airline said four South Korean pilots were on board, three of whom were described as ‘‘skilled.’’
Among the travelers were citizens of China, South Korean, the United States, Canada, India, Japan, Vietnam and France. There were at least 70 Chinese students and teachers heading to summer camps, according to Chinese authorities.
Fei Xiong, a Chinese passenger , was traveling to California so she could take her 8-year-old son to Disneyland. The pair was sitting in the back half of the plane. Xiong said her son sensed something was wrong.Continued...