Airline pilots spend nearly all their time monitoring automated cockpit systems rather than “hand-flying” planes, but their brains aren’t wired to continually pay close attention to instruments that rarely fail or show discrepancies.
As a result, pilots may see but not register signs of trouble, a problem that is showing up repeatedly in accidents and may have been a factor in the recent crash landing of a South Korean airliner in San Francisco, industry and government experts say.
Teaching pilots how to effectively monitor instruments has become as important as teaching them basic “stick-and-rudder” flying skills, a panel of experts told an annual safety conference of the Air Line Pilots Association, the world’s largest pilots union, on Wednesday.
“The human brain just isn’t very well designed to monitor for an event that very rarely happens,” said Key Dismukes, a former top NASA human factors scientist.
Although people “do very well” at actively controlling a plane, “we’re not well designed to monitor for a little alphanumeric (code) on the panel even if that alphanumeric tells us something important,” he said. “We can’t just sit there and stare at the instruments.”
The “sheer volume of monitoring required even on the most routine flights and the diversity” of systems that must be monitored has increased, he said.
Concern about the problem is great enough that government, union and industry safety officials formed a working group last fall to come up with a blueprint for teaching pilots techniques for how to overcome the brain’s natural tendency to sometimes see but disregard important information. For example, if pilots see airspeed indicators showing appropriate speeds landing after landing, their brains may filter out an unexpected low or high speed, they said.
“The human brain filters out information it considers unchanging,” said Helena Reidemar, an airline pilot and the pilots union’s director of human factors.
Asiana Flight 214 crashed short of a runway at San Francisco International Airport on July 6 after a nearly 11-hour flight from Seoul, South Korea. Of the 307 people on board, three have died and dozens of others were injured. One of the issues that have emerged in the National Transportation Safety Board’s investigation of the accident is whether the pilots, who were supposed to be watching airspeed indicators, were aware the plane was traveling at speeds so dangerously slow that it was at risk of losing lift and stalling.
The flight’s pilots set a target airspeed of 137 knots for crossing the runway’s threshold. The plane reached speeds as low as 103 knots just before its landing gear and then its tail collided with a rocky seawall at the end of the runway, shearing off the tail, dumping three flight attendants onto the tarmac and sending the rest of the plane spinning and sliding.
Dismukes cautioned that it’s too soon to reach conclusions about whether the three Asiana pilots who were in the Boeing 777’s highly-automated cockpit were closely monitoring the plane’s airspeed, “but what was going on there in terms of monitoring systems obviously is going to be a crucial issue.”
Robert Sumwalt, an NTSB board member, said: “The question is, did the pilots recognize they were slow? And if not, why not?”
The board’s investigation hasn’t turned up any mechanical or computer problems with the plane, NTSB chairman Deborah Hersman said at briefing last week.
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