WASHINGTON – Asiana Flight 214’s pilots caused the crash last year of their airliner carrying more than 300 people by bungling a landing approach in San Francisco, including inadvertently deactivating the plane’s key control for airspeed, the National Transportation Safety Board concluded Tuesday.
But the board also said the complexity of the Boeing 777’s autothrottle and autoflight director – two of the plane’s key systems for controlling flight – contributed to the crash.
Materials provided to airlines by Boeing that fail to make clear under what conditions the autothrottle doesn’t automatically maintain speed were also faulted.
The 777 has been in service for 18 years and is one of the world’s most popular wide-bodied airliners, especially for international travel.
Until last year’s crash, it had not been involved in a fatal crash.
The board’s acting chairman, Chris Hart, warned that the crash underscores a problem that has long troubled aviation regulators around the globe – that increasingly complicated automated aircraft controls designed to improve safety are also creating new opportunities for error.
The Asiana flight crew over- relied on automated systems that they did not fully understand, Hart said.
In their efforts to compensate for the unreliability of human performance, the designers of automated control systems have unwittingly created opportunities for new error types that can be even more serious than those they were seeking to avoid, he said.
The South Korea airline’s pilot training also was faulted.
Of the 307 people aboard Flight 214, three Chinese teenagers were killed when it crashed July 6, 2013. Nearly 200 people were injured, 49 of whom were seriously hurt.
It remains the only fatal passenger airline crash in the U.S. in the past five years.
Asiana Airlines said it has already implemented the NTSB’s training recommendations and that it agreed with the NTSB’s finding that one factor was the complexity of the autothrottle and autopilot systems, as well as their descriptions in Boeing training manuals.
Boeing immediately rejected the notion that the 777’s automated systems contributed to the crash, pointing to the aircraft’s safety record.
The autoflight system has been used successfully for over 200 million flight hours across several airplane models, and for more than 55 million safe landings, the company said in a statement.
The evidence collected during this investigation demonstrates that all of the airplane’s systems performed as designed, the company said.
The board, which made 27 recommendations to prevent future disasters, didn’t say the autothrottle failed to perform as designed – rather that its design, under certain circumstances, could lead to confusion as to whether it was active or inactive in controlling speed.