N7827A

Probable cause: the local controller s incorrect assumption that the Southwest Airlines (SWA) airplane would depart from the runway before the Federal Express airplane arrived on the same runway, which resulted in a loss of separation between both airplanes. Contributing to the controller s incorrect assumption were his expectation bias regarding the SWA airplane s departure, his lack of situational awareness regarding the SWA airplane s position when the flight crew requested takeoff clearance, and the air traffic control tower s lack of training (before the incident) on low visibility operations. Contributing to the incident was the SWA flight crewmembers failure to account for the traffic that…