Investigation Summary
The investigation revealed that the DC-10's outward-opening cargo doors relied on a latching system that could be forced shut even if the locking pins were not fully engaged. Because the cabin floor was not vented, the sudden pressure differential during decompression caused the floor to collapse into the cargo hold. This collapse severed the redundant hydraulic lines routed through the floor, which were essential for controlling the elevators and rudder. Furthermore, the floor collapse pulled the number two engine throttle to the idle position, complicating the crew's attempts to maintain thrust and recover the aircraft. A similar incident had occurred two years earlier on American Airlines Flight 96 (the 'Windsor Incident'), but the safety recommendations from that event had not been effectively implemented as mandatory fixes.
Final Conclusions
The crash was caused by the failure of the aft cargo door latching system. Contributing factors included the design of the door, which lacked a fail-safe mechanism to prevent pressurization if not properly locked, and the lack of floor venting which led to structural collapse and loss of flight controls. The disaster highlighted significant failures in the FAA's oversight and the manufacturer's response to known design defects.
Video Analysis
The DC-10 Cargo Door Disaster | Turkish Airlines Flight 981 — An in-depth look at the Ermenonville air disaster and the design flaws of the McDonnell Douglas DC-10 cargo door.
If playback is blocked, the owner has disabled embedding — use the link above.
Systems & Failure Modes
Cargo Door Latching Mechanism
An outward-opening door design that used over-center latches and locking pins to secure against cabin pressure.
Hydraulic Control System
The DC-10 used three redundant hydraulic systems, but all were routed through the cabin floor, creating a single point of failure.
Cabin Floor Structure
The floor lacked pressure relief vents, causing it to buckle when the cargo hold decompressed.
Interesting Facts
- 01It was the deadliest aviation accident in history until the 1977 Tenerife airport disaster.
- 02The aircraft was nicknamed 'Ankara'.
- 03A strike at British European Airways led to an unusually high passenger load on the Paris-London leg.
- 04The cargo door latching pins had only moved 7mm, insufficient for a secure lock.
- 05It remained the deadliest single-aircraft accident until the crash of Japan Airlines Flight 123 in 1985.
Safety Actions & Advisories
Mandatory Cargo Door Redesign
Source ↗The FAA issued Airworthiness Directives requiring a complete redesign of the cargo door locking mechanism, including the installation of a support plate to prevent the locking pins from being forced into a locked position when the latches were not fully engaged, and a viewing port to allow ground crews to visually verify pin engagement.
Cabin Floor Venting
Source ↗To prevent structural collapse in the event of a future decompression, manufacturers were required to install pressure relief vents in the cabin floors of wide-body aircraft, allowing air to flow between the cabin and cargo compartments to equalize pressure.
Location
ACCIDENT SITE · Coordinates taken from the wikidata coordinate.