What causes the perception of a spin at wings level during a constant rate spin?

The perception of a spin at wings level during a constant rate spin is primarily influenced by inner ear correction. The inner ear plays a crucial role in the vestibular system, which is responsible for balance and spatial orientation. When an aircraft is in a spin, the continuous rotational motion can lead to a disconnection between what the pilot feels physically and what they observe visually.

As the aircraft is spinning, the semicircular canals in the inner ear detect the rotation. Even when the wings are level, the sensation from the inner ear may still indicate that the aircraft is spinning. This mismatch can create a disorienting feeling of spinning or tumbling, even when the aircraft's orientation appears stable to the pilot. The inner ear tries to correct this sensation based on its interpretation of the motion, thus contributing to the perception of the spin.

Other factors like visual cues from the cockpit or external environmental factors could potentially influence a pilot's perception, but they are secondary to the primary role that the inner ear plays in detecting rotational motion. Cognitive distractions might also affect how pilots interpret sensations, but they do not directly cause the perception of spinning in this context.