One of the latest details revealed about Saturday's crash of Asiana Flight 214 in San Francisco likely raises a question in many minds: After tumbling down the runway and coming to rest, why did the flight crew initially ask passengers to remain in their seats rather than immediately start to evacuate the plane? Instead, an announcement was made for everyone to stay put. It was another 90 seconds or so before the evacuation order was given.

An initial review of what happened indicates the pilots may have thought it was safer to wait for emergency personnel to get to their crippled jet before having passengers get out.

According to what Deborah Hersman, head of the National Transportation Safety Board, told reporters on Wednesday:

-- When the Boeing 777 came to a stop, flight attendants asked the pilots if they should begin evacuation procedures. "The pilots indicated that they were working with air traffic controllers," Hersman said, and asked that passengers be told to stay where they were."We don't know [yet] what the pilots were thinking," Hersman added, "[but] in previous accidents there have been crews that don't evacuate. They wait for other vehicles to come to be able to get the passengers out safely."-- Moments later, however, a flight attendant saw fire outside the aircraft. "Certainly, if there's an awareness that there's fire aboard an aircraft, that's a serious issue," Hersman said. A flight attendant alerted the pilots. "The aircraft evacuation began after that," she said.

"Hindsight is 20/20," Hersman also told reporters. But, she added, "pilots are in the front of the airplane. They really don't have a good sense of what's going on behind them. They need to get that information from the flight attendants."

And when Flight 214's crew got that information, it appears, the evacuation began.

Two people died from injuries they suffered in the crash or immediately after (investigators are looking into whether one person was struck and killed by an emergency vehicle responding to the scene). But all 305 of the other people on board survived.

The NTSB has posted video of Hersman's briefing. Bill posted Wednesday about other details from her presentation.

She also discusses another piece of information — that, as USA Today reports, the pilot has told investigators he was "temporarily blinded by a bright light when 500 feet above the ground. Asked whether it's possible that someone on the ground aimed a laser light at the aircraft, Hersman said, "we really don't know at this point what it could have been."

The potential danger of laser lights aimed at cockpits has been a concern for several years.

Update at 6:55 p.m. ET. NTSB: 'No Anomalous Behavior'

Hersman, at a news conference on Thursday, said there is no sign that the autopilot failed aboard the aircraft.

"There is no anomalous behavior of the autopilot, of the flight director, and of the auto-throttles, based on the FDR data reviewed to date," she said, referring to the 777's flight-data recorder.

She said the first internal call to abort the landing came three seconds before impact and the second abort call was made just 1.5 seconds prior to the crash.

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