WASHINGTON, June 24 (Xinhua) -- U.S. federal accident investigators on Tuesday concluded that "mismanagement" by the pilots of Asiana Flight 214, including confusion over whether one of the airliner's key controls was maintaining airspeed, caused the plane to crash while landing in San Francisco last year.
The U.S. National Transportation Safety Board said that the complexity of the Boeing 777's autothrottle, as well as materials provided by the aircraft maker that failed to make clear when controls don't automatically maintain speed, also contributed to the accident on July 6 last year, which killed three passengers and injured about 200 others.
According to the report, the flight's three veteran pilots made 20 to 30 different errors during the landing approach. The major errors include that pilots didn't follow company procedures on calling out notifications about the plane's altitude, speed and actions they were taking during the landing approach.
Meanwhile, 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.
The board's acting chairman Chris Hart said that the Asiana flight crew "over-relied on automated systems that they did not fully understand."
He warned that the accident underscores a problem that has long troubled aviation regulators around the globe: "increasingly complicated automated aircraft controls designed to improve safety are also creating new opportunities for error."
According to the NTSB report, the 777 has been in service 18 years and is one of the world's most popular wide-bodied airliners, especially for international travel. Until last year's accident, it had not been involved in a single fatal crash.
In addition, the NTSB investigators also blamed South Korea- based airline's pilot training program by saying that the trainee captain at the controls that day lacked the training for landing an aircraft manually.
The Boeing 777, with 307 people on board, crashed and burst into flames during its landing at San Francisco International Airport.