The Asiana Airlines Boeing 777 that crashed at San Francisco's airport on Saturday was travelling "significantly below" its intended speed and its crew tried to abort the landing just seconds before it hit the seawall in front of the runway, the US National Transportation Safety Board said on Sunday.
Information collected from the plane's cockpit voice recorder and flight data recorder indicated that there were no signs of trouble until seven seconds before impact, when the crew tried to accelerate, NTSB Chairwoman Deborah Hersman said at a news conference at the airport.
A stall warning sounded four seconds before impact, and the crew tried to abort the landing and initiate what's known as a "go around" manoeuvre just 1.5 seconds before crashing, Hersman said.
"Air speed was significantly below the target airspeed," she said.
Asiana Airlines said the pilot was in training for the long-range plane and it was his first flight to the airport with the jet.
"It was Lee Kang-kook's maiden flight to the airport with the jet... He was in training. Even a veteran gets training [for a new jet]," a spokeswoman said in Seoul on Monday.
"He has a lot of experience and previously flown to San Francisco on different planes including the B747... and he was assisted by another pilot who has more experience with the 777," the spokeswoman said.
One of the two Chinese teenage girls killed in the incident might have been run over by an emergency vehicle, the local fire department said on Sunday. San Francisco's medical examiner was conducting an autopsy to determine the cause of the girl's death, fire department spokeswoman Mindy Talmadge said.
"One of the deceased did have injuries consistent with those of having been run over by a vehicle," Talmadge said.
More than 180 people were injured in the crash, at least two dozen of them seriously.
Hersman said it was too early to speculate on the cause of the crash. The data recorders corroborated witness accounts and an amateur video, obtained by CNN, that indicated the plane came in too low, lifted its nose in an attempt to gain altitude, and then bounced along the tarmac after the rear of the aircraft hit a seawall at the approach to the runway.
Asked whether the information reviewed by the NTSB showed pilot error in the crash, Hersman did not answer directly.
"What I will tell you is that the NTSB conducts very thorough investigations. We will not reach a determination of probable cause in the first few days that we're on an accident scene," she told reporters.
Asiana said mechanical failure did not appear to be a factor in the crash. Hersman confirmed that a part of the airport's instrument-landing system was offline on Saturday but cautioned against drawing conclusions from that, noting that the so-called glide slope system was not essential to safe operations in good weather. She said it was a clear day with good visibility.
Six people remained in critical condition at San Francisco General hospital on Sunday, including one girl, a hospital spokeswoman said, and 13 others were in less serious condition. Stanford hospital said late on Saturday that three people were in critical condition and 10 in serious condition there.
At least five people were still being treated at other area hospitals on Sunday morning.
Some of the injured at San Francisco general suffered spinal fractures, including paralysis, and others sustained head trauma and abdominal injuries, according to Margaret Knudson, chief of surgery at the hospital.
At least two patients also suffered "severe road rash suggesting they were dragged", Knudson said. The injured patients who were able to talk said they were all sitting in the back of the plane, Knudson said.
The plane was coming in from Seoul when witnesses said its tail appeared to hit the approach area of a runway that juts into San Francisco Bay.
The impact knocked off the plane's tail and the aircraft appeared to bounce violently, scattering a trail of debris and spinning before coming to rest on the tarmac.
Benjamin Levy, a 39-year-old venture capitalist from San Francisco who sat in a window seat near one of the wings, said the flight crew gave "no indication whatsoever" that there was any problem with the landing moments before the aircraft struck the runway.
Following the initial collision, "we're going back up and I'm thinking maybe we're taking off again. We didn't and we went back pretty hard and bounced," he told reporters after being released from San Francisco general
Pictures taken by survivors showed passengers hurrying out of the wrecked plane, some on evacuation slides. Thick smoke billowed from the fuselage and TV footage later showed the aircraft gutted and blackened by fire. Much of its roof was gone.
Interior damage to the plane also was extreme, Hersman said on CNN.
"You can see the devastation from the outside of the aircraft, the burn-through, the damage to the external fuselage," she said. "But what you can't see is the damage internally. That is really striking."
The dead were identified as Ye Meng Yuan and Wang Lin Jia, both 16-year-old girls and described as Chinese nationals who are students, Asiana Airlines said. They had been seated at the rear of the aircraft, according to government officials in Seoul and Asiana, and were found outside the airplane.
The crash was the first fatal accident involving the Boeing 777, a popular long-range jet that has been in service since 1995. It was the first fatal commercial airline accident in the United States since a regional plane operated by Colgan Air crashed in New York in 2009.
"For now, we acknowledge that there were no problems caused by the 777-200 plane or [its] engines," Yoon Young-doo, the president and CEO of the airline, told reporters on Sunday at the company headquarters on the outskirts of Seoul.
Asiana on Sunday said the flight, which originated in Shanghai, had carried 291 passengers and 16 crew members. The passengers included 141 Chinese, 77 South Koreans, 64 US citizens, three Indians, three Canadians, one French, one Vietnamese and one Japanese citizen.
Vedpal Singh, a native of India, was on board the flight along with his wife and son when the aircraft struck the landing strip.
"Your instincts take over. You don't know what's going on," said Singh, who had his arm in a sling as he walked through the airport's international terminal and told reporters he had suffered a fractured collar bone.A senior Asiana official said the pilot was Lee Jeong-min, a veteran pilot who has spent his career with the airline. He was among four pilots on the plane who rotated on two-person shifts during the 10-hour flight, the official said.
Wrack der verunglückten Maschine
Ein Wrackteil vom Heck
Innenraum der verunglückten Maschine
Flugschreiber der Maschine 

 In den USA hat einen Tag nach dem Unglück einer koreanischen Verkehrsmaschine auf dem internationalen Flughafen von San Francisco, bei dem zwei Personen getötet und zehn schwer verletzt wurden, die Suche nach den Ursachen begonnen.

Schon kurz nach dem Unglück waren mechanisches Versagen und das Wetter als Ursache ausgeschlossen worden. Die Leiterin des National Transportation Safety Board (NTSB), Deborah Hersman, gab inzwischen erste Ergebnisse der Auswertung der technischen Daten des Flugdatenschreibers und der Aufzeichnungen der Gespräche aus dem Cockpit bekannt. So verlangte eines der Besatzungsmitglieder sieben Sekunden vor dem Unglück, die Geschwindigkeit zu erhöhen, und 1,5 Sekunden vor dem Unglück wurde versucht durchzustarten. Erste Auswertungen der Flugdaten haben ergeben, dass das Flugzeug deutlich langsamer war als die zu diesem Zeitpunkt zu erwartenden 245 km/h (137 Knoten).

Als Ablauf des Unfalls geht man bisher davon aus, dass das Flugzeug die Uferbefestigung am Anfang der Landebahn berührt hat; dabei brach das Heck des Flugzeugs mit dem Seitenruder ab und das Flugzeug rutschte, bis es neben der Landebahn zum Stillstand kam und wahrscheinlich durch ein abgerissenes Triebwerk Feuer fing. Der genaue Ablauf der Ereignisse wird aber weiter untersucht.

Auch wurde inzwischen bekannt, dass der verantwortliche Pilot erst 43 Stunden Flugerfahrung auf einem Flugzeug des verunglückten Typs Boeing 777-200ER hatte, er aber eigentlich ein erfahrener Pilot mit über 10.000 Flugstunden vor allem auf Maschinen des Typs Boeing 747 ist und auch den Flughafen San Francisco schon öfter angeflogen hat. An Bord waren zwei Pilotenteams, die sich während des Fluges abwechselten, und ein auf der Boeing 777-200ER erfahrener Pilot war während der Landung als Co-Pilot zur Unterstützung ebenfalls im Cockpit.

Auf dem internationalen Flughafen von San Francisco stehen zurzeit verschiedene Unterstützungssysteme nicht zur Verfügung. So gibt es keine Gleitweganzeige, und die Anflugbefeuerung war ausgeschaltet, der Precision Approach Path Indicator und der Localizer waren verfügbar, betonte das NTSB und widersprach damit anderslautenden Meldungen. Diese Systeme helfen dem Piloten, den richtigen Winkel und die richtige Geschwindigkeit für die Landung zu finden. Eine visuelle Eigenkontrolle der Höhe durch den Piloten wird in San Francisco durch den Anflug über das Wasser extrem erschwert. Deutsche Piloten klagten zudem über die amerikanischen Fluglotsen, die extreme Sinkgeschwindigkeiten anordneten, und wiesen auf die dichte Reihenfolge der Landungen hin, die die Landung in San Francisco sehr stressig für Piloten machte. Für ein sehr schweres Flugzeug, wie es die verunglückte Maschine war, können schon kleine Abweichungen von den Idealwerten schwerwiegende Folgen haben. Die Leiterin des NTSB kündigte an, dass die Rolle, die die nicht vorhandenen Unterstützungsysteme bei dem Unfallhergang möglicherweise spielten, genau untersucht würde.

Zu den Opfern wurde inzwischen bekannt, dass am Sonntag (Ortszeit) noch sechs Personen in kritischem und 13 in ernstem Zustand im San Francisco General Hospital behandelt würden. Mindestens fünf weitere Personen wurden noch in anderen Krankenhäusern behandelt. Bei den beiden getöteten Passagieren handelt es sich um zwei 16 Jahre alte Mädchen aus Jiangshan in der chinesischen Provinz Zhejiang, die mit einer Gruppe von 30 Schülern und mehreren Lehrern zu einem Sommercamp in die USA reisen wollten. Bisher unbestätigten Meldungen zufolge wurde eines der Mädchen von einem zur Unglücksstelle eilenden Rettungsfahrzeug überfahren. Mitglieder einer zweiten chinesischen Schülergruppe aus Taiyuan in der chinesischen Provinz Shanxi blieben unverletzt.