A small airport with intersecting runways and no control tower. A mysterious transmission that may have steered a plane into danger. And a malfunctioning air stair door that turned a survivable accident into one of the worst runway disasters in American history. See how small failures culminated in a tragedy that took the lives of everyone on board United Express Flight 5925 at Quincy Regional Airport in Illinois on November 19, 1996. Then follow the investigation that highlighted the importance of listening to preflight safety briefings.