ABSTRACT
Visual illusions of movement may be oculogyral, when a false sense of turning is created, and oculogravic, which is a visual component of the altered perception following a change in the force vector. Low visibility approaches no doubt reflect a critical part of the flight. However, the predominant area of incidents and accidents arising from visual illusions seems to be in non-precision approaches, when the pilot reverts to visual control - often in quite good weather conditions. These are generally recognised as the most critical phases of flight and so visual illusions are potentially more dangerous than at other times. It is sometimes said that as visual illusions result from an unconscious process within the brain, there is really nothing to be done about providing protection against them. Very effective steps can be taken by flight crew members and operational management to reduce substantially the risks associated with visual illusions in flight operations.
