* NTSB interviews the Asiana flight's four pilots
* Pilot at the controls was still training on 777s
* It's too early to conclude pilot error, NTSB chief says
* Firefighters, passengers describe dramatic rescue effort
By Alistair Barr and Hyunjoo Jin
SAN FRANCISCO/SEOUL, July 8 The role of the pilots in Saturday's crash of an Asiana Airlines plane in San Francisco came under increasing scrutiny on Monday as U.S. investigators began to interview them and released new details about the jet's dangerously slow air speed before it slammed into the ground.
The Asiana Airlines Boeing 777 was flying 39 miles per hour below its target speed of 158 mph in the moments before it crashed at San Francisco's international airport, National Transportation Safety Board Chairwoman Deborah Hersman said at a news conference in San Francisco.
Planes can stall at slow speeds, and Hersman said on Sunday a stall warning had sounded four seconds before the crash.
All four pilots from the flight were being interviewed on Monday by investigators from the NTSB and other agencies, Hersman said. Saturday's crash killed two teenage Chinese passengers and injured more than 180 other people.
The pilot at the controls, Lee Kang-kuk, was still training on Boeing 777 jets, the South Korean airline said, and his supervisor was making his first flight as a trainer. Lee had 43 hours of experience flying the long-range jet, Asiana said.
Lee Kang-kuk was making his first attempt to land a 777 at San Francisco's airport, although he had flown there 29 times previously on other types of aircraft, said South Korean Transport Ministry official Choi Seung-youn.
It was not clear whether the senior pilot, Lee Jung-min, who had clocked 3,220 hours on a Boeing 777, had tried to take over to abort the landing.
"All responsibilities lie with the instructor captain," Yoon Young-doo, the president and CEO of the airline, said at a news conference on Monday at the company's headquarters.
Hersman said her team was investigating all aspects of the crash and the rescue efforts. She noted that the tail of the plane had hit the seawall in front of the runway, and part of the tail and other debris had landed in the water. Bits of the seawall were found far down the runway, Hersman added.
She said the NTSB wants to get the facts straight about who was the "flying pilot" in this leg of the flight and "who was the pilot in command in the cockpit."
"We have to understand what these pilots knew. We also need to look at how they were flying the airplane. Were they hand-flying the airplane? Were they relying on auto pilot or some combination of the two of those - and how those systems worked, if they worked as designed, if the crew understood what they were supposed to do," Hersman said in a CNN interview.
But Hersman, whose agency takes the lead in finding the cause of U.S. air crashes, added: "I think it really is too early to conclude pilot error because there's so much that we don't know."
The NTSB had said on Sunday the plane was "significantly below" its intended air speed and its crew tried to abort the landing less than two seconds before it hit the seawall in front of the runway.
On Monday, Hersman offered fresh details, saying the plane was flying at just 119 miles per hour immediately prior to the accident, a full 25 percent slower than normal for the descent.
Hersman referred to the local coroner's office any questions on whether one of the two girls killed in the accident had been run over by a fire vehicle.
San Francisco Fire Department Chief Joanne Hayes White said on Monday: "We have information and evidence to suggest that one of our fire apparatus came into contact with one of the victims at the scene. We're working closely with the NTSB as they conduct their investigation, particularly on this aspect."
The coroner's office did not respond to inquiries about when the autopsy results might be released.
DRAMATIC RESCUE SCENE
San Francisco police and fire officials, at an airport news conference, described a dramatic scene in the moments after the crash, with firefighters quickly putting out an initial blaze and clambering up escape slides to help evacuate passengers.
San Francisco police officer Jim Cunningham, who colleagues said raced onto the plane without any protective gear, described freeing passengers as fire began to engulf the aircraft.
"People had injuries and some were just scared to move," Cunningham said. "When we were getting the last couple of people out, I started coughing. The cabin started filling up with smoke. A black billow of smoke came rushing towards us before we were just about to get off the plane."
Many passengers, especially at the front of the plane, were able to walk off easily. But emergency workers and passengers described a grim situation in other parts of the plane, with some passengers trapped among dislodged seats and an escape chute that had deployed inside the aircraft.
Eugene Rah, a concert producer who lives in the San Francisco suburb of Milbrea, described heroic efforts by a flight attendant he identified as Ji Yeon Kim.
"She was in tears, but she was telling everybody what to do," Rah said in an interview. "She was piggybacking other passengers."
Rah described a frustrating and disorganized situation in the hours after the crash, with survivors receiving little information or help from the airline or local authorities.
The charred aircraft remained on the airport tarmac on Monday as investigators collected evidence even as flight operations gradually returned to normal.
The two girls who died, Ye Mengyuan and Wang Linjia, were friends from the Jiangshan Middle School in Quzhou, located in the prosperous eastern coastal province of Zhejiang.
Ye, 16, had an easy smile, was an active member of the student council and had a passion for biology, the Beijing News reported. "Responsible, attentive, pretty, intelligent," were the words written about her on a recent school report, it said.
Wang, a year older than Ye, also was known as a good student and was head of her class, the newspaper said.
They were among a group of about 35 students on their way to attend a summer camp at the West Valley Christian School in West Hills, near Los Angeles. Pastor Glenn Kirby said the surviving students would now be returning home to China.