In some instances of an aircraft suffering a catastrophic failure of its primary flight controls, the loss of control force on the elevator allows said elevator to drop down under its own weight, causing an immediate crash.
In other loss-of-flight-controls accidents, however, the elevator either stays stuck at its position immediately prior to the control failure, or floats in the airstream:
- JAL 123 (B747, 1985, Mt. Takamagahara)
- LOT 5055 (Il-62, 1987, Warsaw)
- UAL 232 (DC-10, 1989, Iowa)
- DHL OO-DLL (A300, 2003, Baghdad)
Why does elevator dropdown occur during some, and only some, loss-of-flight-controls accidents?