According to the National Transportation Safety Board (NTSB), the fatal crash of Asiana Airlines Flight 214 was caused by the pilots mismanaging the descent toward San Francisco’s airport and not aborting the landing to try again.
Other factors included the complexities of the Boeing 777’s autothrottle, which were inadequately described in the manufacturer’s documents, along with inadequate pilot training and monitoring, the board said.
The board agreed to the cause and contributing factors by a series of 4-0 votes. To avoid future crashes. the board agreed to recommendations including enhancing training for the autothrottle and requiring pilots to land flights manually more often to remain familiar with it.
The board also voted to urge Boeing to change the autothrottle so that it would provide a minimum speed regardless of what part of a flight a plane is in. Investigators found that low-speed protection available in other flight modes would have revved the engines 20 seconds before impact, which would have “likely” prevented the accident, the board said.
“Our goal in this investigation is to help prevent similar accidents in the future,” said Christopher Hart, acting chairman of NTSB. “In this instance, the flight crew over-relied on automated systems that they did not understand.”
The crash July 6, 2013, killed three people and injured 187, out of 307 aboard the flight from Seoul. The plane was flying lower and slower than intended when it slammed into the seawall at the end of the runway, spun around, and burst into flames.
While Asiana acknowledged the pilots were flying too slow and too low, there is a dispute between the airline and Boeing about why that happened.
Asiana cited “inconsistencies” with the autothrottle that led pilots to believe it would maintain the plane’s speed after some adjustments in the autopilot, when in fact the engines were idling in “hold” mode. Boeing has maintained that the plane was functioning as expected and “did not contribute to the accident,” and that the pilots should have aborted the landing when they realized things were awry and tried again. The hold mode is widely used in Boeing wide-body planes. But board members offered different perspectives on the pilot’s confusion dealing with the wakeup feature that was introduced about 18 years in the 777. Robert Sumwalt, a board member who previously was a 24-year airline pilot, said confusion about the autothrottle was widespread in the industry and not well known. He said the pilots were experienced but expected the autothrottle to work differently than it did.
“I personally don’t believe this is a case of crew competency,” Sumwalt said. “It was not just this pilot who misunderstood. I think this problem is a lot more widespread than we may have thought.”
The disputed hold mode for the autothrottle was common among Boeing wide-body planes for decades. Capt. Roger Cox, the investigator who studied operations in the crash, said the Asiana pilot was surprised by the throttle not waking up. “He used the word ‘astonished,'” Cox said.
But Cox said the hold mode was displayed on control panel in front of the pilots. And he said the flying pilot should have called out that he was flying manually, but he didn’t.
“You have to look at them,” Cox said. “There are plenty of cues in front of you telling you what you’ve done, but you have to look at them.” Six people – two passengers and four flight attendants – were ejected from the plane as it broke apart.
The two passengers, who hadn’t been wearing seat belts, died. But investigators found they likely would have survived if they had worn their seat belts. “Seat belts save lives and protect people in all modes of transportation,” board member Mark Rosekind said.
The third dead passenger was struck by a door that detached when the plane struck the ground.