Incident Overview
Description
A Trans World Airlines, Inc., Boeing 707-331B porpoised while descending approximately 35 miles west of Los Angeles, California, USA. The flight was bound for the Los Angeles International Airport. The longitudinal instability persisted for about 2 minutes during which more than 50 pitch oscillations occurred. Peak acceleration forces of +2.4g to -0.3g were measured at the aircraft’s center of gravity. There were 141 passengers and 11 crewmembers aboard. As a result of the accident, one passenger was injured fatally; one flight attendant and two other passengers were injured seriously. The National Transportation Safety Board determines that the probable cause of this accident was a combination of design tolerances in the aircraft’s longitudinal control system which, under certain conditions, produced a critical relationship between control forces and aircraft response. The atypical control force characteristics which were present in this particular aircraft’s control system were conducive to overcontrol of the aircraft by the pilot. The pilot’s normal reaction to an unexpected longitudinal disturbance led to a pitching oscillation which was temporarily sustained by his subsequent application of control column forces to regain.
Primary Cause
Design tolerances in the aircraft’s longitudinal control system, under certain conditions, produced a critical relationship between control forces and aircraft response.Design tolerances in the aircraft’s longitudinal control system, under certain conditions, produced a critical relationship between control forces and aircraft response.Share on:
