Boeing 737 Safety Record

Maintenance personnel’s excessive grinding of the left main landing gear’s aft trunnion pin during machining, which imparted heat damage to the base metal and led to the fatigue cracking that caused the pin to fracture during landing.

A No. 1 (left) engine fire due a fuel leak that originated from the fuel nozzle 17 b-nut connection that was not properly torqued in accordance with the aircraft maintenance manual procedure.

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 was on short final approach and to notify the controller that they would need additional time on the runway before the takeoff roll. Also contributing to the incident was the Federal Aviation Administration’s failure to require surface detection equipment at Austin-Bergstrom International Airport and direct alerting for flight crews.

The American Airlines flight 106 (AAL106) crew’s surface navigation error due to distractions caused by their performance of concurrent operational tasks during taxi, which resulted in a loss of situational awareness. Contributing to the incident was the air traffic control tower team’s nondetection of the AAL106 crew’s deviation from taxi instructions while performing concurrent operational tasks; the timing of the runway status light system, which activated too late to prevent the AAL106 crew from crossing the runway hold short line; and American Airlines’ lack of adequate risk controls to prevent concurrent flight crew tasks from leading to distraction, loss of situational awareness, and deviation from an authorized taxi clearance. Reducing the severity of the incident, and likely preventing an accident, was the activation of the ASDE-X warning in the air traffic control tower and the local controller’s prompt cancellation of DAL1943’s takeoff clearance.