Sensory Systems and Illusions

040-02-02Pablo Asensio Martínez2026-04-011 min

Vision

The primary source of information for pilots ("See and Avoid").

  • Retina: Contains Photoreceptors.
    • Cones: Central vision (Fovea), detailed, color, require bright light (Photopic).
    • Rods: Peripheral vision, movement detection, black & white, sensitive in low light (Scotopic).
  • Blind Spots:
    • Anatomical: Where the optic nerve exits (no receptors).
    • Night Blind Spot: The Fovea (Cones) is blind at night. Pilots must look off-center to use Rods.
  • Empty Field Myopia: In featureless skies (blue sky, haze, dark night), the eye tends to focus at a resting distance of ~1-2 meters, making distant traffic detection difficult.

Vestibular System (Balance)

Vestibular balance system

Located in the inner ear.

  1. Semicircular Canals: Detect angular acceleration (Rotation: Pitch, Roll, Yaw).
  2. Otoliths (Utricle & Saccule): Detect linear acceleration (Gravity, Speed up/down).

Illusions (Spatial Disorientation)

When visual cues are lost (IMS/night), the vestibular system can mislead.

  • The Leans: A slow roll is undetected by the canals (below threshold). A sudden correction feels like a roll in the opposite direction.
  • Coriolis: Moving the head during a steady turn stimulates multiple canals, causing unbearable tumbling sensation.
  • Somatogravic Illusion:
    • Take-off (Acceleration): Otoliths interpret acceleration as a pitch up. Pilot pushes nose down $\rightarrow$ CFIT.
    • Deceleration: Interpreted as pitch down. Pilot pulls nose up $\rightarrow$ Stall.

Hearing

  • Noise Induced Hearing Loss (NIHL): Prolonged exposure to high decibels (>90 dB) damages the hair cells in the cochlea. High frequencies are lost first.