NTSB Probes Pilot's Use of Autothrottles in Asiana Crash
Investigators with the U.S. National Transportation Safety Board (NTSB) focused on pilot training and knowledge of the Boeing 777-200ER autothrottle system during a day-long investigative hearing on December 11 into the crash of Asiana Airlines Flight 214 at San Francisco International Airport.
The widebody struck a seawall short of the runway on July 6, after Asiana pilots flew it more than 10 hours from Seoul and conducted a visual approach to the airport. The crash killed three of the 291 passengers and injured three of the four pilots and 10 of the 12 cabin crew. “The investigation to date has not identified any anomalies with the airplane prior to impact,” although systems testing continues, Bill English, NTSB investigator in charge, told the hearing.
Parties participating in the hearing, held at NTSB headquarters in Washington, D.C., were Asiana Airlines, the Asiana Pilots Union, Boeing, the U.S. Federal Aviation Administration, San Francisco International Airport and evacuation slide manufacturer Air Cruisers. Jeong-kwen Park, director of the aviation investigation team with the Republic of Korea Aviation and Railway Accident Investigation Board, served as the country’s accredited representative to the hearing.
As part of its evidence-gathering process, the NTSB organized panels of expert witnesses to answer questions in the areas of Boeing 777 flight deck design concepts; Asiana Airlines pilot training on the 777; the influence of automation on pilot performance; and the emergency response to the crash.
English started by summarizing the pilots’ actions on the flight deck preceding the crash. The pilot flying, positioned in the left seat, was a captain transitioning from the Airbus A320 to the 777 with the less 45 hours in the latter type. A newly certified instructor pilot with 3,200 hours in the 777 monitored from the right seat. One of two relief first officers sat in the jump seat.
Data indicates that at an altitude of 1,600 feet and 3.5 miles from the runway, the flight level change switch on the mode control panel—normally used to climb or descend to selected altitudes—was activated, changing the autopilot and autothrottle operating mode. “It is not recommended to use flight level change past the final approach fix, according to the Boeing flight crew training manual,” English said, describing this action along a continuum of actions leading to the crash.
Nadine Sarter, a University of Michigan professor and human factors expert, testified that “mode error” is one of the most common errors associated with automated flight systems. She described it as resulting from “mode awareness, being that you are aware of the current and future state of the automation and if you are not, that might lead to an error that is appropriate for the assumed but not the actual state of the automation.”
Deborah Hersman, NTSB chairman, said the Board’s target is to complete the investigation before the one-year anniversary of the accident. “We have talked a lot today about training, about experience, about knowledge of automation and automated systems, particularly in the 777,” she said following the 12-hour hearing. “Clearly automation is a huge issue in the aviation community.”