 This is the most common illusion during flight, and can be caused by a sudden return to wings-level flight following a gradual application of bank that had gone unnoticed by the pilot.The reason a pilot can be unaware of such an attitude change in the first place is that human exposure to a rotational acceleration of ~1 degrees per second² or lower is below the detection threshold of the semicircular canals.Rolling wings-level from such an attitude may cause an illusion that the aircraft is banking in the opposite direction.