Anchor: The U.S. federal agency investigating the crash-landing of an Asiana Airlines passenger jet in San Francisco has recovered the plane's black box and begun analysis.  Kwon Chae-ryung has what they have found so far.
 
Report: U.S. National Transportation Safety Board Chairwoman Deborah Hersman disclosed an initial black box analysis on Sunday local time, saying the flight data recorder is in good condition and data of the past 24 hours is intact.
 
Hersman said that based on findings so far, while landing, the plane was traveling at speeds well below the target landing speed of 137 knots per hour (254 kilometers per hour) and also at a low altitude. 
 
She said there were no unusual signs up until seven seconds prior to the crash when a pilot suddenly ordered an increase in speed. It's also confirmed that the stick shaker, a piece of safety equipment that warns pilots of an impending stall, went off four seconds before the crash. The pilot then tried to increase altitude one and a half seconds before the plane's tail clipped a seawall between the runway and San Francisco Bay.   

The safety board chief said so far no mechanical faults have been found with the plane and there are no reports of weather playing a factor. U.S. officials are also looking into flight records and previous experience of the Asiana jet pilots. The officials plan to conduct in-depth interviews with the pilots. 
 
The chief investigator, however, stressed that the case is under probe from all perspectives and authorities remain open to all possible causes of a pilot blunder, aircraft defect or problems with the airport system. She urged people to refrain from making conjectures and that onsite inspection alone will take a week, and from a year to a year and a half to reach a final conclusion. 
 
Two 16-year old Chinese teenage girls were killed and more than 180 passengers were injured when the Boeing 777 smashed into a runway at San Francisco International Airport on Saturday.
Kwon Chae-ryung, KBS World Radio News