Investigators have found no evidence of mechanical problems with Asiana Flight 214, the head of the National Transportation Safety Board said Thursday, putting the focus of the safety probe into the crash landing at the San Francisco airport squarely on the pilots.

In her final briefing before the agency concludes its on-site detective work, NTSB Chairman Deborah Hersman said the airplane itself showed no signs of a breakdown, and on voice recorders, the pilots of the Boeing 777 fail to notice that their approach is dangerously low and slow until it’s too late.

“There is no mention of speed until about nine seconds before impact when they’re at 100 feet,” she said Thursday. Just seconds before impact, two of the pilots call for the landing to be aborted.

Investigators have stressed that nothing has been definitively ruled out and no firm conclusions reached. The agency’s final evaluation is expected to take more than a year.

The airliner itself, though heavily damaged in the crash, had no malfunctions in any critical systems, including the engines and flight-control surfaces, the autopilot, the autothrottles and the flight director, she said.

Two people were killed and 180 of the 307 people were hurt Saturday when the airliner slammed into a seawall at the end of the runway. The impact ripped off the back of the plane, tossed out three flight attendants and their seats and scattered pieces of the jet across the runway as it spun and skidded to a stop.

The battered passengers, some with broken bones, were told over the jet’s public-address system to stay in their seats for another 90 seconds while the cockpit consulted with the control tower, a safety procedure to prevent people from evacuating into life-threatening fires or machinery.

And in this accident, authorities are investigating whether one of the two Chinese teens who died may have been run over by a fire truck rushing to the burning jet.

Hersman has said repeatedly that pilots Lee Gang-kuk, who was landing the big jet for his first time at the San Francisco airport, and Lee Jeong-Min, who was training him were ultimately responsible for a safe landing.

The NTSB investigators will soon head back to Washington with “a mountain of information” to analyze and review, from pieces of the airliner to interview transcripts.

A firefighter who scrambled aboard the jet looking for victims as fire was breaking out told inspectors the seats in that section of the aircraft were almost pristine.

“He said it looked like you just fluff the pillows and turn the airplane around it can go out for its next flight.”

That section soon erupted in flames caused by oil spilling on hot engines. The fuel tanks did not rupture, Hersman said Thursday.

The FAA has found “no significant issues” during 134 unannounced mechanical, pilot or avionic checks on Aviana airliners over the last 18 months, said Hersman.

Hersman clarified Thursday that the pilot trainee told investigators he saw a flash of light at about 500 feet, which would have been 34 seconds before impact and the point at which the airliner began to slow and drop precipitously. She said he told investigators that the light did not prevent him from seeing his instruments, and that it may have been a reflection of the sun. The other pilots made no mention of a light, she said.

While the pilots were manually flying the jet for the landing, as expected on a clear, sunny day, they told investigators they thought the airliner’s speed was being controlled by an autothrottle set for 157 mph.

Inspectors found that the autothrottle had been “armed,” or made ready for activation, Hersman said. But investigators are still determining whether it had been engaged. In the last two minutes, there was a lot of use of autopilot and autothrottle, and investigators are going to look into whether pilots made the appropriate commands and if they knew what they were doing, she said.

Experts said the evidence points toward pilot error.

Lee Collins, a pilot with 18,000 hours and 29 years of experience on a variety of airliners, said the question is how the Asiana pilots could make such a “gross error.”

“What caused this airplane to crash was their failure to maintain proper airspeed,” Collins said.

During the evacuation, many passengers jumped out the back of the plane or slid down inflated slides through emergency exits. Then, say some, an unnerving wait began. 911 tapes recorded frantic callers, pleading for help.

“We’ve been on the ground, I don’t know, 20 minutes, a half hour,” said one woman. “There are people laying on the tarmac with critical injuries, head injuries. We’re almost losing a woman here. We’re trying to keep her alive.”

San Francisco Fire Department spokeswoman Mindy Talmadge said Thursday that some passengers who called 911 may not have immediately seen ambulances at the scene because they were dispatched to a nearby staging area as first responders assessed who needed to be taken to the hospital.

“There is a procedure for doing it,” Talmadge said. “You don’t cause more chaos in an already chaotic situation. You don’t do that with 50 ambulances running around all over the place.”

Within 18 minutes of receiving word of the crash, five ambulances and more than a dozen other rescue vehicles were at the scene or en route, in addition to airport fire crews and crews from San Mateo County and other agencies already on the scene, Talmadge said.

“Our response was immediate,” Talmadge said. “It’s not what you may see in the movies. That’s not how a real-life response is to a large-scale incident.”

(AP)