American Airlines Flight 1813

During engine start, while being pushed back, both engines went to a high power setting. The airplane pushed forward against the tow bar, sheared a pin, bent the tow bar, and struck the tug. Before engine start, maintenance personnel had conducted an automated check which included automatic movements of the control wheel and throttles. The flight crew returned to their seats while the test was being conducted. At the completion of the test, the airplane was returned to service and maintenance personnel departed the cockpit. The captain initiated the BEFORE STARTING ENGINES checklist without either pilot first completing a cockpit flow setup as required by company procedures. The checklist was then interrupted by a cockpit visitor and a non-pertinent conversation took place for 3 1/2 minutes. When the checklist was resumed, several items had been missed. As the checklist was continued, the call out THRUST LEVERS was made by the first officer, and the correct response of CLOSED was given by the captain. Push back was initiated, and the captain verbalized starting the first engine as required by the checklist. As the first engine was being started, the captain initiated another non-pertinent conversation with the first officer. The second engine was then started without verbalization as required by company checklist procedures. Although company checklist procedures made both pilots responsible for ensuring a normal start, neither pilot detected that the engines were accelerating above normal idle. According to follow-up testing, the engines accelerated to a power setting that corresponded to the last position of the throttles at the completion of the automated test by maintenance.

Verbatim NTSB analysis and probable cause from the NTSB dataset