"If there are four pilots there, even if you are sitting on a jump seat, that's something you watch, the airspeed and the descent profile," said John Cox, a former US Airways pilot and former Air Line Pilots Association accident investigator.
Investigators want to nail down exactly what all four Asiana pilots were doing at all times.
"We're looking at what they were doing, and we want to understand why they were doing it,." Hersman said Monday. "We want to understand what they knew and what they understood."
It's unlikely there was a lot of chatter as the plane came in. The Federal Aviation Administration's "sterile cockpit" rules require pilots to refrain from any unnecessary conversation while the plane is below 10,000 feet so that their attention is focused on taking off or landing. What little conversation takes places is supposed to be necessary to safely completing the task at hand.
Choi Jeong-ho, a senior official for South Korea's Ministry of Land, Infrastructure and Transport, told reporters in a briefing Tuesday in South Korea that investigators from both countries questioned two of the four Asiana pilots, Lee Gang-guk and Lee Jeong-min, on Monday. They planned to question the other two pilots and air controllers Tuesday.
Choi said recorded conversation between the pilots and air controllers at the San Francisco airport would be investigated, too.
In addition, authorities were reviewing the initial rescue efforts after fire officials acknowledged that one of their trucks might have run over one of the two Chinese teenagers killed in the crash. The students, Wang Linjia and Ye Mengyuan, were part of a larger group headed for a Christian summer camp with dozens of classmates.
Asiana President Yoon Young-doo arrived in San Francisco from South Korea on Tuesday morning, fighting his way through a pack of journalists outside customs.
He said he will look at the efforts of airline employees to help injured passengers and their family members, visit with the NTSB and other organizations to apologize for the crash and try to meet injured passengers.
Yoon said he can't meet with the Asiana pilots because no outside contact with them is allowed until the investigation is completed.
More than 180 people aboard the plane went to hospitals with injuries. But remarkably, more than a third didn't even require hospitalization.
The passengers included 141 Chinese, 77 South Koreans, 64 Americans, three Canadians, three Indians, one Japanese, one Vietnamese and one person from France.
South Korea officials said 39 people remained hospitalized in seven different hospitals in San Francisco.
The flight originated in Shanghai, China, and stopped over in Seoul, South Korea, before making the nearly 11-hour trip to San Francisco.