SAN FRANCISCO (AP) - Pilots of Asiana Flight 214 were flying too slowly as they approached San Francisco airport, triggering a cockpit 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.
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, Hersman said. 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.
There was no indication in the discussions between the pilots and the air traffic controllers that there were problems with the aircraft.
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.
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.
"My son told me: "The plane will fall down, it's too close to the sea,'" she said. "I told him: "Baby, it's OK, we'll be fine.'"
When the plane hit the ground, oxygen masks dropped down, said Xu Da, a product manager at an Internet company in Hangzhou, China, who was sitting with his wife and teenage son near the back of the plane. When he stood up, he said he could see sparking - perhaps from exposed electrical wires.
He turned and could see the tail where the galley was torn away, leaving a gaping hole through which they could see the runway. Once on the tarmac, they watched the plane catch fire, and firefighters hose it down.
In the chaotic moments after the landing, when baggage was tumbling from the overhead bins onto passengers and people all around her were screaming, Wen Zhang grabbed her 4-year-old son, who hit the seat in front of him and broke his leg.
Spotting a hole at the back of the jumbo jet where the bathroom had been, she carried her boy to safety. I had no time to be scared," she said.
"Think you said people are just walking outside the airplane right now?" the controller replied.
"Yes," answered the pilot of United Flight 885. "Some people, it looks like, are struggling."
At the crash scene, police officers knives up to crew members inside the burning wreckage so they could cut away passengers' seat belts. Passengers jumped down emergency slides, escaping from billowing smoke that rose high above the bay. Some passengers who escaped doused themselves with water from the bay,