The vestibular system in the inner ear senses head movement and position. It is evolutionarily designed for ground motion — and a dangerous source of misinformation in flight.
Construction
Two main components in the inner ear (labyrinth):
| Component | Senses | Mechanism |
|---|---|---|
| Semicircular canals (three, mutually perpendicular) | Angular acceleration (rotation) | Endolymph fluid lags — during rotation the cupula deflects |
| Otolith organs (utricle, saccule) | Linear acceleration and gravity | Calcium carbonate crystals on hair cells — displacement creates signal |
Limitation: acceleration sensors only
| Movement | Vestibular detects? |
|---|---|
| Sudden start of rotation | Yes (angular acceleration) |
| Constant rotation rate | No — after 10–20 s system believes still |
| End of rotation | Yes — felt as rotation in the other direction |
| Acceleration (e.g. take-off) | Yes — can be mistaken for pitch-up |
| Constant velocity | No |
| Vertical acceleration (lift, climb) | Yes — can be mistaken for pitch change |
Consequence for flight
In VFR with clear visual reference: vision corrects the vestibular misinformation. In IMC or with limited visibility: only the instruments are reliable.
→ Golden rule: in IMC trust the instruments, not your inner ear.
Examples of typical misinterpretations
These are covered in detail in §6.3 (Spatial Disorientation):
- Leans — slow bank not detected
- Coriolis — head movement during a turn causes violent tumbling sensation
- Graveyard spiral — unnoticed descending spiral
- Somatogravic illusion — take-off acceleration felt as pitch-up
Training
Practical spatial disorientation training is part of modern pilot education — rotating chairs or VR simulators expose the discrepancy between perception and reality.