The flight data recorder (FDR) recovered from the Asiana Airlines Boeing 777-200ER that crash landed at San Francisco International Airport on Saturday indicates that the airplane slowed to 103 knots—or 34 knots below the airspeed identified as appropriate for landing—some three seconds before its tail section hit the sea wall at the threshold of Runway 28L, according to National Transportation Safety Board chairman Deborah Hersman. While issuing her second formal media briefing on the crash on Monday in San Francisco, Hersman also confirmed reports that one of the captains hadn’t yet earned his type rating in the Boeing 777 and that the hours he spent flying the airplane from Seoul accounted for some of what she called “initial operating experience” in that particular model. She did describe the pilot as experienced in other types, however. In all, four pilots worked the flight.
“When we interview the four crewmembers we’ll get a lot more details about their activities, about their work, about their training, about who was the pilot flying, who was the pilot-in-command in the cockpit at the time of the accident,” said Hersman. “We’re going to be looking to correlate all of that information with what we are finding on the cockpit voice recorder and the flight data recorder.”
The airplane’s CVR recorded no discussion of any aircraft anomalies or concerns with the approach, said Hersman. One of the crewmembers did call for more engine power some seven seconds before impact, however. Some three seconds later, the stick shaker activated, indicating an imminent stall, and only 1.5 seconds before impact, the crew called for a go-around.
Further FDR data showed that the airplane’s autopilot disengaged at 1,600 feet, some 82 seconds before impact. While descending from 1,400 feet to 250 feet, the 777 decelerated from 170 knots to 112 knots in 65 seconds. The airplane hit the ground while traveling at 106 knots—three knots faster than the slowest recorded speed. Engine power had increased from idle to 50 percent at the time of impact.
Two of the 307 passengers and crew aboard Asiana Flight 214 died after the tail of the 777 struck the sea wall at the threshold of SFO’s Runway 28L upon landing, sending it careening off the pavement until it came to rest several hundred feet from the point of impact. Rescuers sent 182 of the occupants to area hospitals with injuries, some life-threatening, while 123 walked away from the wreckage.
Hersman couldn’t confirm reports that an emergency vehicle had run over one of the dead passengers. “It is a very serious issue and we want to understand it,” said Hersman. “The coroner has not yet determined the cause of death…We are reviewing airport surveillance video to understand what happened. I will tell you that at least the initial read of the video by our investigators…wasn’t conclusive.”
Questioned about the operation of instrument landing system, Hersman reported the existence of a Notam (Notice to Airmen) indicating that the airport’s glideslope wouldn’t function from June 1 to August 22, while crews worked on a construction project. However, the ILS’s localizer remained in operation, and airport officials stressed that all required navigation tools at the airport worked properly at the time of the crash. Later, the FAA issued a Notam of inoperative precision approach path indicator lights damaged by the crash.
Although visual flight rules (VFR) prevailed at the time of the accident, Hersman said investigators still didn’t know whether or not the pilots opted to fly the approach entirely “by hand” or with the use of automation such as GPS-based navigation tools in the cockpit.