The National Transportation Safety Board (NTSB) says failures by the crew ultimately caused the crash of Asiana Airlines flight 214 in San Francisco last year, although a number of factors contributed to the crash.

In a statement released today, the agency points to a number of contributing factors, including Boeing’s failure to adequately document complexities in the aircraft’s systems, failures in Asiana’s flight training and crew fatigue.

The aircraft, a Boeing 777-200ER, crashed into the airport seawall after its speed decayed to 103kt.

The accident killed two passengers. A third passenger likely survived being ejected from the aircraft, only to be killed after being hit by emergency response vehicles, investigators have said.

Prior to the crash, the aircraft’s autothrottle transitioned in “hold” mode while the aircraft’s flight computer was in “flight-level change mode,” a configuration under which the autothrottle does not maintain speed.

During a hearing today, the NTSB pegged the accident on the pilot’s false assumption that the autothrottle would maintain speed in that configuration. It also pointed to the crew’s failure to manage the descent, monitor airspeed or initiate a timely go-around.

But the board also pointed a finger at Boeing, saying the manufacturer did not properly document system complexities that have proved in a number of other instances to have confused pilots.

The board also highlighted shortcomings with the Asiana's training.

Boeing disagrees the with NTSB’s finding that the 777s flight systems contributed to the accident, telling Flightglobal that the aircraft has an “extraordinary record of safety.”

“The auto-flight system has been used successfully for over 200 million flight hours across several airplane models, and for more than 55 million safe landings,” says the company in a statement. “The evidence collected during this investigation demonstrates that all of the airplane's systems performed as designed. “

Asiana says the NTSB has “properly recognised the multiple factors that contributed to the accident, including the complexities of the autothrottle and autopilot systems.”

“The recommendations made by the agency can help ensure such an incident does not happen again,” says the airline.

Asiana flight 214 probably cause

The hearing concluded after more than three hours with the NTSB reading 27 recommendations aimed at preventing a repeat of the accident and improving accident response.

Those included calls for the Federal Aviation Administration (FAA) to require Boeing to improve training and documentation related to the 777’s systems and to require operators to adopt that training.

The board also suggests that the FAA convene a “special certification review” of the 777's automatic control systems and develop guidance to help manufacturers “improve the intuitiveness” of systems.

In addition, the NTSB suggests that the FAA convene a panel to study an a onboard “low-energy alerting system.” Such a system could take into account factors like airspeed, altitude and engine performance to prevent an aircraft from reaching a near-stall.

The NTSB’s recommendations to Boeing include a call to modify the 777’s flight control system to “expand the conditions under which the autothrottle automatically protects speed.”

Boeing says it will review the NTSB’s recommendations, but adds that aircraft design changes should be “reviewed with great care and with due consideration for the potential unintended consequences of any change.”

The board also recommends that Asiana improve training for both pilots and monitoring pilots and adopt more manual flight training to improve proficiency.

Asiana says it has already implemented the NTSB’s training recommendations.

NTSB Asian flight 214 recommendations

Source: Cirium Dashboard