Experiencing a traumatic event such as surviving a plane crash can result in symptoms of post-traumatic stress, but everybody experiences these symptoms differently, and scientists are not sure why. An airplane crashed in South Korea on Sunday, killing 179 of the 181 people on board, including all its passengers and four of six crew members. The passenger plane burst into flames after skidding off a runway into a wall at an airport after the plane's landing gear apparently failed to deploy, shortly after the pilot received a warning of a bird strike. Two flight attendants were rescued from the back of the aircraft and are being treated for non-life-threatening injuries.