Which vestibular illusion is characterized by a sense of falling or climbing when flying straight and level?

The vestibular illusion that is characterized by a sense of falling or climbing while flying straight and level is known as the "leans." This illusion occurs when the pilot experiences a discrepancy between their equilibrium sensations from the inner ear and the actual orientation of the aircraft.

When a pilot is in a banked turn, the inner ear can become accustomed to that banked position. If the pilot suddenly levels the aircraft, they may feel a sensation as if they are falling away from the bank, leading them to mistakenly believe they are still in a turn. This can create the sensation of climbing or descending, even when the aircraft is actually in straight and level flight.

Understanding this illusion is crucial for pilots as it can affect their spatial orientation and decision-making. Recognizing the leans helps prevent erratic control inputs driven by false sensations of movement, prompting pilots to rely more on their instruments for accurate situational awareness.