The Boeing Co. 777 is one of the world’s most advanced jets, capable of flying automatically most of the time and catching pilot errors before they endanger a flight. That technology may also be a drawback.
Because it’s so tempting to let the 777 fly itself, pilots can allow their flying skills to atrophy or become confused when systems don’t work as expected, said aviation safety experts and pilots who have flown it.
Determining how the pilots of Asiana Airlines Flight 214 interacted with the jet’s automation has become a top priority for investigators looking into why the plane crash-landed at San Francisco International Airport on July 6, U.S. National Transportation Safety Board Chairman Debbie Hersman said yesterday in an interview.
“You’ve seen a lot of investigations internationally” in which aircraft automation contributed to an accident, Hersman said. “It’s not a new thing.”
Two people died and scores were injured when the tail of the Asiana 777 arriving from Seoul struck a seawall short of the runway and the plane slid across the ground. The jet had slowed to 40 miles (64 kilometers) per hour below its target landing speed on approach and was in danger of losing lift, according to preliminary information from the flight-data recorder.
The crew didn’t begin evasive action until seven seconds before impact, Hersman has said. The pilot at the controls had only 43 hours of experience in the wide-body 777 after advancing from narrow-body jets, and was making his first landing at San Francisco in that aircraft type. The management pilot sitting next to him got approval to train other pilots a month earlier.
The flight’s arrival required more manual flying skills than usually needed in San Francisco because a radio beam known as a glide slope, used to automatically guide planes to the runway, was inoperable, according to the safety board.
Cockpit automation has played a role in several recent accidents by confusing pilots, particularly when they became startled or the equipment acted in unusual ways, Rory Kay, the former air safety chairman of the Air Line Pilots Association, said in an interview. ALPA is the largest pilots’ union in North America.
“How well trained are we to handle departure from the norm?” said Kay, who declined to discuss the Asiana accident.
On Feb. 25, 2009, a Turkish Airlines Inc. Boeing 737-800 crashed on approach to Amsterdam, killing nine people. An erroneous altitude reading caused the plane’s automatic throttles to slow the plane, causing it to lose lift and plunge to the ground, the Dutch Safety Board concluded.
While the pilots had several opportunities to prevent the accident, the plane’s automated systems worked against them, the investigation concluded. After pilots added power to regain speed, for example, the autopilot pulled the power back again, according to the investigation.
“A series of small misunderstandings start to accumulate that put the plane into a situation that makes the plane harder to handle,” David Woods, an Ohio State University engineering professor who has studied the issue, said in an interview.
The U.S. Federal Aviation Administration is now trying to determine whether pilot training should better address cockpit automation, Woods said.
The technology is so good that pilots have come to rely on it, Woods said.
“It is making things go smoothly and effectively. When it doesn’t, it’s kind of a surprise,” he said.
Pilots today need to have technical savvy as well as traditional “stick and rudder” skills, John Cox, a former airline pilot who has participated in NTSB investigations, said in an interview.
“The concern is the pilots who become automation-dependent to the degradation of their manual flying skills,” Cox said.
The 777, like similar Airbus SAS models, has automatic systems to prevent the plane from going too slowly. Investigators will want to know how the flight crew set the plane’s speed, and whether the systems malfunctioned or were overridden, Cox said.
“Technology is a two-edged sword,” former NTSB Chairman Jim Hall said in an interview on Bloomberg Television today. “It can provide great safety on modern aircraft, but at the same time we have to be prepared if that technology is not available.”
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