Pilots in Asiana crash relied on automatic equipment for airspeed
Pilots in Asiana crash relied on automatic equipment for airspeed
The pilots aboard the Asiana Airlines Boeing 777 that crashed in San Francisco relied on automatic equipment - an auto-throttle system - to maintain airspeed and did not realize the plane was flying too slowly until it was just 200 feet above the ground, the head of the U.S. National Transportation Safety Board said on Tuesday.
In her third detailed briefing on Saturday's crash that killed two Chinese passengers and injured more than 180 other people, NTSB Chairwoman Deborah Hersman also said two flight attendants were ejected from the plane after its tail hit a seawall in front of the runway and was torn off. Both were found injured but alive on the side of the runway.
Hersman said many questions remained about the incident. The South Korean airline's flight crew members were not tested for drugs or alcohol after the crash, a requirement for pilots of U.S.-based carriers involved in accidents, she said.
The accounts given to investigators by the pilots, as relayed by Hersman, confirmed information from the plane's flight data recorder that showed the plane was traveling 25 percent below its target airspeed as it came in for landing.
While she has declined to speculate on the cause of the crash, much of the information released by the NTSB suggests pilot error as a main focus of the investigation.
The pilot in charge of landing the plane on Saturday was in training on the 777 and was roughly halfway through the process, while seated next to him was a co-pilot on his first flight as an instructor. Both were experienced pilots, although they had not flown together before, Hersman said.
"At about 500 feet, he realized that they were low," Hersman told reporters, referring to the instructor pilot's account of the failed last-second attempts to avoid Saturday's disaster. "Between 500 and 200 feet, they had a lateral deviation and they were low. They were trying to correct at that point."
Referring to the instructor pilot, she said it was not until 200 feet that "he recognized the auto-throttles were not maintaining speed" and tried to abort the landing. Hersman had previously said that the plane had been at an altitude of 200 feet 16 seconds before crashing.
Three of the four pilots on board were in the cabin during the landing, although only two could see the runway, Hersman said, citing the interviews by investigators with the crew.
Hersman said an examination of the wreckage showed that the auto-throttle was "armed," but it was not clear if it had been properly engaged or had somehow failed before the plane slowed to a near-stall and hit the ground. "We need to understand a little better" how the auto-throttle is used, she said.
"They had set speed at 137 knots (158 mph), and he assumed that the auto-throttles were maintaining speed," Hersman said of the instructor pilot.
She noted that the pilots were responsible for maintaining airspeed.
"We have a flying pilot and two other pilots in the cockpit and they have a monitoring function," she said. "One of the critical things that needs to be monitored on an approach to landing is speed. So we need to understand what was going on in the cockpit and also what was going on with the aircraft."
REUTERS