The flight was carrying 181 passengers and crew when it belly-landed before slamming into a barrier, killing all aboard except two flight attendants.

South Korean police raided the offices of Jeju Air and the operator of Muan International Airport Thursday, as the investigation into the deadly Dec. 29 plane crash that killed 179 people ramped up.

For decades, Boeing has maintained a role as one of the giants of American manufacturing. But the the past year's repeated troubles have been damaging.