SAN FRANCISCO — The pilots of the Asiana jet that crashed here Saturday believed that they had set the auto throttles, devices that can control the engines to maintain safe airspeed, but speed fell to unsafe levels anyway, the chairwoman of the National Transportation Safety Board said Tuesday.
Investigators in the cockpit of the wreckage found the auto -throttle switches set to the “armed” position, meaning that the auto-throttle could have been engaged, depending on various other settings, she said. The disclosure is far from conclusive, but raises the clear possibility that there was a mechanical failure or that the crew misunderstood the automated system it was using.
The chairwoman, Deborah A.P. Hersman, also said that interviews with the three pilots who were in the cockpit at the time of impact showed that the speed indicator on the flat-panel displays in the cockpit had drifted down into a crosshatched area, meaning that the instruments were saying that the plane was moving too slowly.
At the dual controls, the pilot flying the plane was undergoing initial training as he upgraded from a smaller plane, and was supervised by a veteran pilot who was new as an instructor, Hersman said. The instructor told investigators that between 500 feet and 200 feet in altitude, the crew was also correcting from a “lateral deviation,” meaning that the plane was too far to the right or left (she did not specify which) and realized they were too low.
At 200 feet, the instructor pilot told investigators in an interview, he noticed they were too slow. “He recognized that the auto throttles were not maintaining speed,” and began preparing the airplane to go around for another try. But it was too late.
Hersman made clear that the safety board was looking to see if there was a generic problem with the runway and the approach path. Her agency requested data from the Federal Aviation Administration, which operates the air traffic system, on other recent arrivals by Boeing 777s, and recent go-arounds, cases in which crews broke off the approach because of a problem.
As the investigation continued, others — including lawyers, passenger advocates, and a pilots union — began jockeying for position.
The crash resulted in an unusual mix of deaths and injuries, said Robert A. Clifford, an aviation lawyer in Chicago, who pointed out that lawyers in his specialty are usually pursuing wrongful-death claims, not personal injury ones. Injured passengers will need legal help, he said.
But Hans Ephraimson-Abt, who leads the Air Crash Victims Families Group, and who frequently lobbies for passenger rights and represents the families of people killed, said that under the governing international law, those injured were covered by a no-fault provision. Under the 1999 Montreal Protocol, he said, “they are entitled to be reimbursed for all their property damages, and economic and noneconomic damages, including psychological counseling.” All that was required, he said, was to show medical bills or calculate lost earnings.
On Tuesday, Clifford said that another party, not covered by the Montreal Protocol, could be vulnerable to claims: Boeing. The plane did not have an aural warning of low airspeed, he said, even though the safety board recommended 10 years ago that the Federal Aviation Administration convene a panel of experts to consider installing them. If the plane was unsafe, he said, the manufacturer could face suits.
A retired 777 captain, Robert Maurer, who flew for American Airlines and later Air India, said that many foreign carriers had a reluctance to land the plane manually, and thus lacked proficiency in the technique.
The Asiana crew was attempting a manual landing on Saturday because an instrument landing system was out of service. And though there were four pilots on the Asiana plane, three of them very experienced in the 777, pilots in some cultures are reluctant to contradict a pilot at the controls, Maurer said.
In fact, the safety board has investigated previous accidents in which cultural factors have reduced the effectiveness of the crew, and that is one of the areas of inquiry here, investigators said.
On Tuesday, a pilots union, the US Airline Pilots Association, issued a statement critical of the safety board, asserting that the board’s quick release of “incomplete, out-of-context information” had “fueled rampant speculation about the cause of the accident” and created the impression that it was pilot error.