Asiana
Crash Pilot Set Throttle He Didn’t Understand to Idle (2)
An Asiana Airlines Inc. (020560) pilot nervous about making a
manual landing in San Francisco inadvertently disabled a speed-control system
before the plane crashed into a seawall on July 6, documents show.
Captain Lee Kang Kuk, a veteran pilot with Seoul-based Asiana
who was being trained on the Boeing Co. (BA:US) 777-200ER
wide-body, had momentarily adjusted the power without realizing the plane’s
computers then assumed he wanted the engines to remain at idle, according to
information released today at a U.S. National Transportation Safety Board
hearing.
The documents, while showing the pilots made errors, raise
questions about how auto-throttles on Boeing planes are designed and whether
there’s enough training on using them. The safety board hasn’t concluded what
caused the crash, which killed three teenage girls from China in the first U.S.
airline accident with deaths since 2009.
Lee, 45, “believed 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 in a summary of an interview with him. “That was the
theory at least, as he understood it.”
In most modes of operation, the speed-protection system on the
777 and several other Boeing aircraft won’t allow planes to slow too much,
protecting against accidents such as the Asiana crash. The plane, on the verge
of losing lift because it was almost 40 miles (64 kilometers) per hour slower
than its target speed, broke apart after hitting the ground.
‘Speed’ Warning
In some combinations of auto-throttle and autopilot settings,
such as during Asiana Flight 214’s approach to San Francisco, the system
becomes dormant, according to NTSB documents.
The three pilots in the cockpit didn’t sense the impending
danger until seconds before impact, according to NTSB documents and a
voice-recorder transcript made public at the start of the hearing.
Bong Dong Won, 40, a crew member on board to give the pilots a
rest break, said at least twice that the plane was descending too quickly in
the final minute, according to the transcript.
Lee and Lee Jung Min, 49, an instructor pilot monitoring the
captain as part of his training on the 777, failed to abort the landing after
the plane descended below 500 feet (152 meters), as was required under airline
rules, according to the documents.
Flights that are below target speed once they descend to 500
feet should abort landings and climb, according to Asiana rules. The plane also
was flying too low, another criteria for calling off the landing.
Too Late
No one commented immediately after a series of chimes 11 seconds
before impact indicated that the plane had reached dangerously low speed,
according to the transcript.
“Speed,” Lee Jung Min said three seconds later. An unidentified
person said “speed” again 1.2 seconds later.
Shortly after the plane descended below 50 feet (15 meters), the
plane’s control column began shaking to warn pilots they were in danger of
losing lift, known as an aerodynamic stall, according to the recording.
Only then, 8.5 seconds after the initial speed warning, did Lee
Jung Min command to abort the landing and climb, according to the transcript.
The pilots added power too late to prevent the collision.
‘Very Concerned’
Lee Kang Kuk, asked about his approach to the airport, told
safety-board investigators it “was very stressful, very difficult.” He wasn’t
accustomed to landing without an instrument-landing system guiding him to the
runway, as pilots had to do in San Francisco that day because of airport
construction, according to an NTSB summary of his statement.
Two former Asiana pilots said in interviews that most of the
carriers’s crews were uncomfortable with manual flight maneuvers, according to
NTSB documents. The pilots gave a similar account in interviews with Bloomberg
News in July.
An FAA study released last month found that pilots’ growing
reliance on automation in the cockpit has led to occasional confusion and new
safety risks.
Autopilots, automatic throttles and computerized navigation
systems have helped improve safety in recent decades, the FAA study concluded.
The price for that is occasional confusion because the systems, which sometimes
interact with each other, may be improperly set or act in ways that crews don’t
anticipate, it said.
Pilots accustomed to having automation handle mundane flying
tasks may also lose basic manual flying skills, the report said
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