Both engines on a South Korean Boeing 777 were working normally when the plane made an underspeed approach and crash-landed on the runway of San Francisco International Airport, the National Transportation Safety Board said Monday.
The airplane was flying more than 37 mph slower than the minimum recommended approach speed three seconds before its tail hit the sea wall on the apron of the runway, the NTSB said.
“Three seconds before impact it was traveling at 103 knots,” NTSB Chairman Deborah A.P. Hersman said Monday after her investigators examined the damaged engines and studied flight data recorders. “One hundred thirty-seven knots is the speed they want to have when they cross the [runway] threshold. The engines indicate that both engines were producing power.”
The pilot was a veteran aviator but a novice at handling the massive Boeing 777, and he had not landed at the California airport before, Asiana Airlines said Monday.
Although Lee Gang-guk had logged 10,000 hours on other airplanes, including the Boeing 747, he had been at the controls of a 777 for just 43 hours, a spokeswoman for the South Korean airline said in Seoul.
NTSB investigators said they planned to interview the two pilots who were in the cockpit and two others with whom they rotated duties during the more-than-10-hour flight across the Pacific Ocean.
“We are certainly looking at pilot performance, and we’re looking at communication between the two crew members,” Hersman said. “But everything is still on the table.”
In describing data taken from the cockpit and flight data recorders Monday, Hersman said that the plane was on a straight, 17-mile approach to the runway and that the pilot told air traffic controllers that he had the runway within sight.
She said data show that 82 seconds before the crash, the plane’s autopilot was not engaged. The recorder indicated that the plane slowed below the appropriate approach threshold 34 seconds before it hit the wall, dropping to 112 knots with eight seconds left in its flight.
Hersman said the cockpit recorder revealed that seven seconds before impact, there was a call to increase the plane’s speed. Three seconds later, a “stick shaker” — a violent vibration of the control yoke — warned that the plane was about to stall. Just 11 / 2 seconds before impact, a crew member called out to abort the landing.
Hersman said it would take weeks, if not months, before her agency reached a conclusion on what caused the crash.
Two Chinese teenagers were killed and scores of passengers were injured just before noon Saturday, when the airliner struck the sea wall at the end of the runway tail-first and skidded about 2,000 feet before catching fire.
That only two people died in the crash was being hailed as a miracle Monday, but the survival of the other 305 on board was more than good fortune. After more than 10 hours in flight, the center wing fuel tank just beneath the passengers was probably close to empty.
Moreover, as the result of the 1996 midair explosion of TWA Flight 800 off Long Island, the Asiana flight would have been equipped with a system that filled the drained tank with nitrogen, eliminating oxygen that might have allowed for combustion.
In the most exhaustive investigation in NTSB history, the agency concluded that an electrical spark in TWA 800’s near-empty center-wing fuel tank cause the plane’s explosion.
Aboard Asiana Flight 214 on Saturday, passengers had time to flee the airplane before fire consumed the cabin from the cockpit area back to behind the wings.
Asked Monday whether she agreed that it was “a miracle” so many survived, Hersman stopped short of that.
“This was a survivable accident,” she said, despite major structural damage to the plane. “The majority of airplane crashes are survivable.”