For anti-collision purposes, the identification of an aircraft requires perception of its presence, detection of its track, and determination of its relative altitude. This evaluation will be recorded by the cerebral cortex and give rise to decisions regarding the action to be taken, which will vary from one individual to another. The avoidance manœuvre will be dictated by the situation and the rules of avoidance, and will involve a psychomotor coordination. Time is the essential factor in the chain of events, since the speed of the pilot's reactions will reduce the possibility of collision.