U.S. National Transportation Safety Board investigators work at the scene of the Asiana Airlines Flight 214 crash site at San Francisco International Airport in San Francisco

 
U.S. National Transportation Safety Board investigators work at the scene of the Asiana Airlines Flight 214 crash site at San Francisco International Airport in San Francisco
U.S. National Transportation Safety Board (NTSB) investigators work at the scene of the Asiana Airlines Flight 214 crash site at San Francisco International Airport in San Francisco, California in this handout photo released on July 7, 2013. REUTERS/NTSB/Handout