Spacial Disorientation
Flying requires several sensory systems to work together:
- Vestibular system: organs found in the inner ear that sense position by the way we are balanced
- Somatosensory system: nerves in the skin, muscles, and joints that, along with hearing, sense position based on gravity, feeling, and sound
- Visual system: eyes, which sense position based on what is seen
There are many situations where visual references outside the aircraft are lost, and the normal motions of the aircraft create convincing illusions that are difficult to overcome.
Illusions
- The leans
- After a long gradual turn, unnoticed by the pilot, the airplane is returned to level flight
- After leveling the wings may feel like the plane is banking in the opposite direction
- Coriolis illusion
- When in a long turn, a swift head movement can make it feel like the airplane is preforming a maneuver that it's not
- Graveyard spiral
- In a prolonged, coordinated turn, the pilot may sense that the aircraft is not turning at all
- When the aircraft is turned back to level flight, the disoriented pilot may believe the aircraft is turning in the opposite direction, and return to the original bank
- The turn can cause the aircraft to lose altitude, and pulling back to correct this simply tightens the turn
- Somatogravic illusion
- Aircraft acceleration may cause the sensation of pitching up
- Likewise, deceleration may cause the sensation of pitching down
- Inversion illusion
- An abrupt change from climb to straight-and-level flight can create the illusion of tumbling backwards
- Disoriented pilots may then push the aircraft abruptly into a nose-low attitude
- Elevator illusion
- An abrupt upward vertical acceleration, as can occur in an updraft, can create the illusion of being in a climb
- Disoriented pilots may then pull the aircraft abruptly into a nose-up attitude