Spatial disorientation specifically refers to the lack of orientation with regard to the position, attitude, or movement of the airplane in space. The body uses three integrated systems that work together to ascertain orientation and movement in space.

• Vestibular system—organs found in the inner ear that sense position by the way we are balanced
• Somatosensory system—nerves in the skin, muscles, and joints that, along with hearing, sense position based on gravity, feeling, and sound
• Visual system—eyes, which sense position based on what is seen

The Leans – when a banked attitude, to the left for example, may be entered too slowly to set in motion the fluid in the “roll” semicircular tubes.

Coriolis Illusion – The pilot has been in a turn long enough for the fluid in the ear canal to move at the same speed as the canal.