Asiana Airlines Flight 214 swooped over San Francisco Bay that summer day, its instruments indicating it was too high to start a safe landing.
The pilots adjusted the altitude but inadvertently shut off the automatic throttle. That caused the Boeing 777 to gradually slip below the required speed and altitude for a proper approach.
By the time the crew noticed, it was too late. A stall warning went off, and within seconds the wide-body jet carrying more than 300 passengers and crew had slammed into a sea wall bordering San Francisco International Airport. The plane cartwheeled down the runway before bursting into flames.
On Tuesday, the National Transportation Safety Board delivered its final report on the litany of blunders that left three dead and 187 injured, some of them Chinese high school students headed for a Christian summer camp. It was the first major commercial aircraft accident in the United States in five years.
Federal experts concluded that the pilots mismanaged the landing and over-relied on an automatic throttle, the use of which they did not completely understand. Had it been operated properly, the device might have prevented the accident, investigators said.
The four-member NTSB panel, which met in Washington, also blamed the pilots' failure to monitor airspeed and altitude, and said they waited too long to abort the landing for another try.
In addition to the main causes of the July 6 crash, the NTSB concluded that a number of factors contributed to it, including the complexity of the Boeing's computerized flight systems and fatigue that probably degraded the performance of the pilots during the long flight from South Korea to the U.S.
The panel also stated that the captain at the controls lacked the training to fly the jet manually and his instructor, who had 3,200 hours in Boeing 777s, failed to supervise him properly or intervene at crucial times.
Heading into the airport "there are cascading errors. Some were corrected," said Roger Cox, the NTSB's senior air safety investigator. "But as the approach proceeded, the errors compounded."
Attorneys for Los Angeles firm Kreindler & Kreindler, which represents crash victims and relatives of the dead , said the findings could help resolve pending lawsuit claims.
"The conclusions contribute to our view that crew mismanagement on approach was initially caused by their confusion over Boeing's automatic throttles," Kreindler attorney Brian Alexander said.
During the hearing, the NTSB weighed the skill and training of Asiana's pilots, the effect of computerized flight systems on their awareness and the response by San Francisco's emergency personnel.
Much of the discussion focused on the design of the Boeing 777's throttle system that automatically adjusts airspeed if it drops off sharply. Asiana officials have contended that the design is flawed and that the device is confusing to use.
Investigators found that the pilots inadvertently deactivated the device when they did not completely turn off the plane's automated flight systems during the approach. Consequently, the automatic throttle went into "hold mode" and could no longer adjust airspeed if it dropped.
Although automatic throttles have been used on Boeing 777s for 18 years, NTSB officials were concerned that Boeing's and Asiana's manuals do not fully explain how the system works.
Board member Robert Sumwalt, a former airline pilot, noted that some other pilots have been confused by the throttle and he questioned whether training was lacking on the limitations of the device.
William Bramble, another NTSB investigator, said the Asiana pilots did not follow standard airline procedures during the landing, such as calling out changes in control settings, airspeed and altitude. He added that the inconsistent adherence to operating procedures in a complex working environment is an indication that they were tired.
Asiana officials said Tuesday they agreed with the conclusions, stating that the NTSB "properly recognized the multiple factors that contributed to the accident, including the complexities of the autothrottle and autopilot systems, which the agency found were inadequately described by Boeing in its training and operational manuals."
During the hearing, the NTSB praised the emergency response at the airport and noted that public safety agencies were so well staffed that they were able to free five passengers trapped in the burning wreckage. They noted that there were 23 airport firefighters, far more than the minimum requirement of three.
Board members said, however, that improvements could be made in communications, the training of commanders for aircraft accidents and the use of firefighting vehicles with booms that can penetrate fuselages and extinguish interior fires. They added that procedures should be developed to prevent emergency vehicles from hitting crash victims, which happened to one 16-year-old passenger who had been thrown from the wreckage, apparently already dead.
Overall, the NTSB made 27 recommendations to the Federal Aviation Administration, Asiana Airlines, Boeing Co. and public safety agencies in San Francisco. They call for a variety of improvements in training, emergency communications and testing of aircraft evacuation devices, such as inflatable slides. Two opened inside Flight 214 after the crash.
Key among the recommendations is enhanced training for using Boeing's automatic throttles and reviews to help the company refine the devices. The NTSB also called for a working group to come up with a better landing alert system for pilots that considers a number of parameters such as altitude, airspeed and the capabilities of jet engines.
Asiana officials say they are already overhauling the airline's safety procedures and improving training to sharpen flying skills, such as increasing the hours of flight simulator training for landings without relying on automated systems.
The carrier has vowed to add safety specialists, improve maintenance and hire consultants to evaluate its procedures. Meanwhile, the South Korean government is considering an increase in training requirements and tougher penalties for airlines when accidents result in casualties.
"We again express our great sorrow for the accident, the loss of life and the injuries sustained by the passengers and crew," Asiana officials said. "The recommendations made by the agency can help ensure such an incident does not happen again."
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