SAN FRANCISCO (KCBS/KPIX 5) — The first sign of trouble for a Korean passenger jet that crashed at San Francisco International Airport on Saturday came seven seconds before impact – the point where the crew realized they were too slow on their approach to land, the chairwoman of the National Transportation Safety Board said Sunday.

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Deborah Hersman said both black boxes, the flight data recorder and cockpit voice recorder from Asiana Airlines Flight 214, were recovered and analyzed at a laboratory in Washington, D.C. yielding some key “preliminary information.”

The cockpit voice recorder reflected a call to increase speed seven seconds before the crash occurred, which was the first indication that something went awry.

“We’re not talking about a few knots,” Hersman said. “We’re talking about a significant speed below 137 knots,” or 160 miles per hour, which is the targeted landing speed.

Hersman said that was followed by indications the plane was about to go into a stall four seconds before impact and then an unsuccessful call by the crew to abort the landing just 1 1/2 seconds prior to crashing.

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She noted that air traffic controllers were unaware of any problems with the landing until they saw the plane hit a seawall before the runway begins.

The crash of the Boeing 777 aircraft claimed the lives of two passengers and injured over 180 others.

Despite the initial findings, Hersman cautioned it was way too early in the probe to say whether pilot error, or an unknown mechanical issue, were to blame for causing the crash.

Hersman said there did appear to be significant differences between Saturday’s crash and the crash of a Boeing 777 at London’s Heathrow Airport a few years ago that injured nearly 50 people.

Most notably, she said, the engine manufacturer for the two planes were different. The Heathrow flight suffered a mechanical problem.

“At this time we haven’t identified any type of similarities” between the two incidents, Hersman said.

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