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Related to leans: leans against
An illusion in which the pilot perceives the aircraft to be tilted, leading him or her to lean the aircraft in the opposite direction to balance it. The pilot is unable to perceive changes along the lateral axis of the aircraft. If an aircraft is banked to any one side at a rate lower than 2°/s and the pilot does not refer to the instruments (and other outside visual clues are absent), he or she may not perceive this change and may believe that the aircraft is still flying with the wings level. If the wings are then leveled, the pilot will feel that the aircraft is banked in the reverse direction and may tend to bank (lean) it to the original side.