Mismanagement by the pilots of Asiana Flight 214 caused the plane to crash while landing in San Francisco last year, the National Transportation Safety Board has concluded.
But the board on Tuesday has also took the unusual step of faulting the complexity of the Boeing 777's autothrottle, as well as materials provided by the aircraft maker that fail to make clear under what conditions the automated system doesn't automatically maintain speed, saying they contributed to the accident.
The board's acting chairman, Chris Hart, warned that the accident 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.
Boeing immediately rejected the notion that the 777s automated systems contributed to the accident, pointing to the aircraft's safety record.
Investigators said the flight's three veteran pilots made 20 to 30 different errors, some minor and others significant, during the landing approach on July 6, 2013.
Among the errors were that they didn't follow company procedures on calling out notifications about the plane's altitude, speed and actions they were taking during the landing approach.
They also weren't closely monitoring the plane's airspeed – a fundamental of flying. Instead, they assumed the autothrottle was maintaining the required speed for a safe landing.
Three people were killed in the crash.
Two were Chinese teens seated in the back, who weren't wearing their seatbelts and were thrown from the plane.
A third teen was hit on the head by one of the plane's doors but survived the crash.
She was killed when, lying unconscious, she was run over by two rescue vehicles in the chaos afterward. Nearly 200 people were injured.
