Asiana Pilots Raise Throttle Malfunction: Crash Investigators Haven't Found Electrical or Mechanical Problems in Preliminary Probe

October 7, 2013, 5:47 p.m. ET

By ANDY PASZTOR

The Wall Street Journal


Pilots of an Asiana Airlines Inc. jet that crashed while trying to land in San Francisco are offering an account that differs from the preliminary findings of U.S. investigators, people familiar with the investigation said.

The pilots have told the National Transportation Safety Board that an in-flight malfunction of an automated speed-control system was a major factor in the fatal accident on July 6, these people said.

So far safety-board investigators haven't uncovered any mechanical or electrical problems with the twin-engine jet prior to impact, these people said. Instead, the NTSB is focused on why the three pilots in the cockpit didn't adequately monitor the approach and failed to check airspeed until it was too late.

The pilots, according to these people, have told U.S. investigators they believe an automated speed-control system, called auto-throttles, disconnected on its own, allegedly without any warning to the crew, shortly before the Boeing 777 slowed dangerously then slammed into a sea wall in front of a runway at San Francisco International Airport and broke apart.

NTSB officials previously said the cockpit crew "assumed the auto-throttle was maintaining speed," but investigators also suggested the pilots may have failed to activate it correctly.

"'Armed' does not mean 'active,'" acting safety board Chairman Deborah Hersman said during an on-site news conference in July. When pilots rely on such automation to adjust engine thrust during landings, she said at the time, "a big key is to monitor" the system and keep close track of aircraft speed.

The pilots' statements—along with details of Asiana 777 maintenance logs showing a number of "uncommanded auto-throttle disconnects"—are part of the arguments Asiana officials intend to make during a planned visit to the NTSB later this year, according to people familiar with the details. The carrier may raise the same issue at a public hearing on the crash the board plans to hold early next year. The NTSB is in charge of the accident probe.

Officials at Asiana and a special South Korean government committee investigating the crash declined to comment. An NTSB spokeswoman couldn't be reached.

But according to people familiar with the status of the probe, the pilots' comments are the most detailed effort by the airline so far to explain why an experienced crew may have been lulled into a false sense of confidence.

Three people were killed and dozens were injured in the high-profile accident, which prompted debate over Asiana's training practices and operations. In the wake of the crash, which destroyed the aircraft, Asiana promised the South Korean government it would enhance training for aviators, update its data on airports with difficult approaches and move to ensure better communication in the cockpit.

At the public hearing, safety board officials are likely to focus on those issues in addition to operation of the auto-throttle system.

The pilots of Asiana Flight 214 have repeatedly told investigators they recall properly arming and engaging the plane's auto-throttle to maintain safe speed during the visual approach in good weather to the San Francisco runway. At an altitude of 500 feet, the approach was on track with the engines idle.

Within the next few seconds, the speed dropped, the plane's nose rose and by time pilots realized the danger, it was too late to rev the engines and try to climb away from the field.

Data from the jet's flight-data recorder doesn't show the auto-throttle engaged at all during the final part of the descent, according to people familiar with the probe. Asiana, however, is expected to bring up at least one other example of Boeing 777 auto-throttles disconnecting, on their own, at another airline.

Source:   http://online.wsj.com

NTSB Identification: DCA13MA120
Scheduled 14 CFR Part 129: Foreign operation of Asiana Airlines
Accident occurred Saturday, July 06, 2013 in San Francisco, CA
Aircraft: BOEING 777-200ER, registration: HL7742
Injuries: 3 Fatal.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators traveled in support of this investigation and used data obtained from various sources to prepare this aircraft accident report.

On July 6, 2013, about 1128 pacific daylight time, Asiana Airlines flight 214, a Boeing 777-200ER, registration HL7742, impacted the sea wall and subsequently the runway during landing on runway 28L at San Francisco International Airport (SFO), San Francisco, California. Of the 4 flight crewmembers, 12 flight attendants, and 291 passengers, about 182 were transported to the hospital with injuries and 3 passengers were fatally injured. The airplane was destroyed by impact forces and postcrash fire. The regularly scheduled passenger flight was operating under the provisions of 14 Code of Federal Regulations Part 129 between Incheon International Airport, Seoul, South Korea, and SFO. Visual meteorological conditions prevailed at the time of the accident.