The crash of an Asiana Airlines Boeing 777 in San Francisco on Saturday is only the second major accident for the twin-engine, wide-bodied jet in the 18 years the model has been in service, aviation safety expert said.
"The 777 has a fantastic record," said Tom Haueter, who retired last year from the National Transportation Safety Board, where he was the head of aviation accident investigations.
The two accidents share a striking similarity -- both occurred just about the time the planes were touching down to landing.
The previous accident occurred on Jan. 17, 2008, at London's Heathrow Airport. In the process of landing, British Airways Flight 28 from China landed hard about 1,000 feet short of the runway and then slid onto the runway. The impact broke the 777-200's landing gear. There were 47 injuries, but no fatalities.
An investigation revealed ice pellets had formed in the fuel while the plane was flying at high altitudes, clogging the fuel-oil heat exchanger. As a result, fuel was blocked from reaching both of the plane's engines. The Rolls-Royce Trent 800 series engines that were used on the plane were fixed afterward to prevent similar problems.
Bill Waldock, an expert on aviation accident investigation, said he was reminded of the 2008 Heathrow accident as he watched video of Saturday's crash in San Francisco.
The Asiana 777 "was right at the landing phase and for whatever reason the landing went wrong," said Waldock, director of the Embry-Riddle Aeronautical University accident investigation laboratory in Prescott, Ariz. "For whatever reason, they appeared to go low on approach and then the airplane pitched up suddenly to an extreme attitude, which could have been the pilots trying to keep it out of the ground."
Waldock cautioned: "Of course, there is no indication directly that's what happened here. That's what the investigation is going to have to find out."
While the two accidents appear to have occurred about the point in landing, "you can't rule out anything thing at this point," Haueter said.
"I think it's someone who got slow and low on the approach, quite frankly, but we won't know anything until we see the flight data recorder," he said.
Haueter said was doubtful the Asiana accident will be linked to the same icing problem as that caused the British Airways accident since changes were made after that crash to prevent further incidents.
"Most accidents happen during takeoff and landing anyway," he said.
Safety improvements to planes in recent years -- better fire-proofing of passenger cabins and reinforcements to fuel systems -- may have prevented the San Francisco accident from becoming much worse, Waldock said.
Commonly referred to as the "Triple Seven," the 777 is a long-range jet designed primarily for extended flights over water. The plane that crashed in San Francisco was coming from Seoul, South Korea.
The 777 had its first flight in 1994 and was introduced into service in 1995. As of last month, Boeing had delivered more than 1,100 of the planes to airlines around the world.