Pilots of the Asiana Airlines Inc. plane that crashed in San Francisco last year relied too much on cockpit automation they didn’t understand, an investigator said at the start of a hearing to establish the accident’s cause.
The U.S. National Transportation Safety Board today is discussing recommendations to address how flight crews interact with the computerized systems of modern airliners, acting agency Chairman Christopher Hart said in opening remarks.
“The more complex automation becomes, the more challenging it is to ensure that the pilots adequately understand it,” he said.
The Boeing Co. 777-200ER struck a seawall after the pilots of the Seoul-to-San Francisco flight allowed the jetliner to get almost 40 miles (64 kilometers) per hour slower than the target speed as they neared the runway. The July 6 accident that killed three teenage girls was the first in the U.S. with passenger fatalities since 2009.
The pilots mismanaged their approach to the airport, failed to notice the deteriorating speed and lights near the runway showing they were too low, and then didn’t to abort the touchdown, which they were trained to do in such circumstances, according to the NTSB.
An underlying reason for the accident was that Captain Lee Kang Kuk, a veteran of the airline who was being trained on the Boeing 777 wide-body, didn’t realize he had disabled the jetliner’s automatic speed protection system as he was trying to descend, according to the NTSB.
Lee told investigators after the crash he thought “the auto-throttle should have come out of the idle position to prevent the airplane going below the minimum speed” for landing, the NTSB said.
Another Asiana captain, Lee Jung Min, an instructor, was seated in the co-pilot’s seat.
The probe has also concluded that fatigue played a role in the pilots’ performance, Bill Bramble, a human-factors investigator at the NTSB, said in a presentation at the hearing.
Chicago-based Boeing, in a submission to the NTSB on the accident, said crew actions caused the accident.
“The airplane and all airplane systems were functioning as expected prior to impact and did not contribute to the accident,” Boeing said in the submission in March.
The 777, the largest twin-engine jetliner, began commercial service in 1995 and has one of the industry’s best safety records, according to Boeing’s annual aircraft accident summary.
While Seoul-based Asiana said in its submission the pilots were at fault, it urged the NTSB to find that issues with the plane’s automation were also to blame.
Incidents with an almost identical auto-throttle issue arose in certification of the Boeing 787, NTSB documents show.
The FAA required Boeing to add a note to the then-new 787’s documentation warning pilots they could lose speed protection under the same circumstances, according to the documents. An FAA test pilot flying the 787 in 2010 said he was surprised to learn that the plane’s speed protection could be lost in some cases. The changes weren’t required for the 777.