NTSB Probable Cause

THE LOSS OF CONTROL OF THE AIRPLANE FOR UNDETERMINED REASONS FOLLOWING THE INFLIGHT OPENING OF THE IMPROPERLY LATCHED CARGO DOOR. CONTRIBUTING TO THE ACCIDENT WERE: INADEQUATE PROCEDURES USED BY EVERGREEN AIRLINES AND APPROVED BY THE FAA FOR PREFLIGHT VERIFICATION OF CARGO DOOR SECURITY, EVERGREEN'S FAILURE TO MARK PROPERLY THE AIRPLANE'S EXTERNAL CARGO DOOR LOCKPIN MANUAL CONTROL HANDLE, AND THE FAILURE OF MCDONNELL DOUGLAS TO PROVIDE FLIGHTCREW GUIDANCE AND EMERGENCY PROCEDURES FOR AN INFLIGHT OPENING OF THE CARGO DOOR. ALSO CONTRIBUTING TO THE ACCIDENT WAS THE FAILURE OF THE FAA TO MANDATE MODIFICATION TO THE DOOR-OPEN WARNING SYSTEM FOR DC-9 CARGO-CONFIGURED AIRPLANES, GIVEN THE PREVIOUS KNOWN OCCURRENCES OF INFLIGHT DOOR OPENINGS.