24 June 2014
Last updated at 16:31
The crew of the Asiana flight that crashed in San Francisco “over-relied on automated systems” the head of the US transport safety agency has said.
Chris Hart, acting chairman of the National Transportation Safety Board (NTSB), said such systems were creating serious errors.
The NTSB is meeting to vote on the probable cause of the crash, which killed three people in July 2013.
It was the only fatal passenger airline accident in the US in five years.
The aircraft hit a seawall as it approached the airport runway, ripping off the tail and sending the body of the airplane skidding down the runaway, which then caught fire.
Three people died in the crash – including one Chinese teenager who was run over by a firefighting vehicle in the chaos.
During the meeting on Tuesday, Mr Hart said the Asiana crew did not fully understand the automated systems on the Boeing 777, but the issues they encountered were not unique.
“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,” Mr Hart said.
Asiana has acknowledged the crew failed to monitor and maintain the plane’s airspeed, which was likely to have been the cause of the accident, according to documents made public by the NTSB.
The South Korea-based airline said those flying the plane reasonably believed the automatic throttle would keep the plane flying fast enough to land safely.
But that feature was shut off after a pilot idled it to correct an unexplained climb earlier in the landing.
The airline argued the automated system should have been designed so that the auto throttle would maintain the proper speed after the pilot put it in “hold mode”.
Boeing has been warned about this feature by US and European airline regulators.
NTSB board members are voting on the probable cause of the crash after a nearly-year long investigation
“Asiana has a point, but this is not the first time it has happened,” John Cox, an aviation safety consultant, told the Associated Press news agency.
“Any of these highly automated airplanes have these conditions that require special training and pilot awareness. … This is something that has been known for many years.”
Other issues found in the investigation are ones that have been a concern in aviation for years.
The pilot that was flying the plane at the time of the crash, Captain Lee Kang-kuk, told investigators that he did not immediately move to abort the landing after it became unstable because he felt only the instructor pilot had that authority.
Deference to senior pilots were identified as a factor in several South Korean airliner crashes in the 1980s and 90s, but procedures relating to cockpit culture were overhauled in South Korea, as well as in the US, after those findings.