Investigators scrutinizing the events leading up to Saturday's Asiana Airlines plane crash in San Francisco are examining the behavior of the pilots in the minutes leading up the crash—during which the Boeing 777 was flying at a dangerously low rate.

The crash killed two teenage passengers from China and injured another 180 people. Just before it crashed, the plane was traveling 39 miles below the target speed of 158 mph.

National Transportation Safety Board Chairwoman Deborah Hersman revealed new details yesterday—the plane was flying at just 119 miles per hour before the accident, which is 25 percent slower than normal speeds for descent. The investigation will focus on why the pilot crew allowed the speed to decrease for such a long time, as well as why the pilots did not take any action until two seconds before impact.

At a news conference in San Francisco on Sunday, Hersman said that a stall warning had sounded four seconds before the plane crash. She also emphasized that there was "no prior distress call" from the plane's crew.

The pilot at the controls, Lee Kang-kuk, was in training, with only 43 hours flying a Boeing 777. This was his 9th training flight and the first flight into the San Francisco airport. According to industry experts, a large portion of the pilot's 43 hours would have been logged onto a 777 simulator, rather than an actual plane—if Asiana follows global industry standards. Additionally, he would have been under supervision by a training captain.

All four pilots are being questioned as part of the investigation.

Hersman stressed that the method of flying and the use of controls needed to be examined before any conclusions could be made. In a CNN interview, Hersman said, "I think it really is too early to conclude pilot error because there's so much that we don't know."

The two young women who died, Ye Mengyuan and Wang Linjia from the eastern Chinese province of Zhejiang, were on their way to summer camp in California. It is still unclear whether one of the two young woman was run over by an approaching rescue vehicle after the crash, as has been speculated. The San Francisco Fire Department Chief Joanne Hayes White stated yesterday:

"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."

[image via AP]