The latch of the DC-10 is a study in
human factors,
interface design and engineering responsibility. The control cables for the rear control surfaces of the DC-10 are routed under the floor, so a failure of the hatch could lead to the collapse of the floor, and disruption of the controls. To make matters worse, Douglas chose a new latch design to seal the cargo hatch. If the hatch were to fail for any reason, there was a very high probability the plane would be lost.
This possibility was first discovered in 1969 and actually occurred in 1970 in a ground test. Nevertheless, nothing was done to change the design, presumably because the cost for any such changes would have been borne as out-of-pocket expenses by the fuselage's sub-contractor, Convair. Although Convair had informed McDonnell Douglas of the potential problem, rectifying what the airline considered a small problem with a low probability of occurrence would have seriously disrupted delivery of the aircraft and cost sales so Convair's concerns were ignored.
Dan Applegate was Director of Product Engineering at Convair at the time. His serious reservations about the integrity of the DC-10's cargo latching mechanism are considered a classic case in the field of
engineering ethics.
After Flight 981, a complete re-design of the latching system was finally implemented. The latches themselves were re-designed to prevent them from moving into the wrong positions in the first place. The locking system was mechanically upgraded to prevent the handle from being able to be forced closed without the pins in place, and the vent door operation was changed to be operated by the pins, so that it would properly indicate that the pins were in the locked position, not that the handle was. Additionally, the
FAA ordered further changes to all aircraft with outward-opening doors, including the DC-10,
Lockheed L-1011, and
Boeing 747, requiring that vents be cut into the cabin floor to allow pressures to equalize in the event of a blown-out door.
The name given to the crashed DC-10, "Ankara", is still used on an
Airbus A340-300 (TC-JDL, MSN: 57) in Star Alliance Livery.