AIM 

4/20/23 

b.  Illusions Leading to Spatial Disorientation. 

1. 

Various complex motions and forces and certain visual scenes encountered in flight can create illusions 

of motion and position. Spatial disorientation from these illusions can be prevented only by visual reference to 

reliable, fixed points on the ground or to flight instruments. 

2.  The leans. 

An abrupt correction of a banked attitude, which has been entered too slowly to stimulate 

the motion sensing system in the inner ear, can create the illusion of banking in the opposite direction. The 

disoriented pilot will roll the aircraft back into its original dangerous attitude, or if level flight is maintained, will 

feel compelled to lean in the perceived vertical plane until this illusion subsides. 

(a) Coriolis illusion. 

An abrupt head movement in a prolonged constant-rate turn that has ceased 

stimulating the motion sensing system can create the illusion of rotation or movement in an entirely different axis. 

The disoriented pilot will maneuver the aircraft into a dangerous attitude in an attempt to stop rotation. This most 

overwhelming of all illusions in flight may be prevented by not making sudden, extreme head movements, 

particularly while making prolonged constant-rate turns under IFR conditions. 

(b)  Graveyard spin. 

A proper recovery from a spin that has ceased stimulating the motion sensing 

system can create the illusion of spinning in the opposite direction. The disoriented pilot will return the aircraft 

to its original spin. 

(c)  Graveyard spiral. 

An observed loss of altitude during a coordinated constant-rate turn that has 

ceased stimulating the motion sensing system can create the illusion of being in a descent with the wings level. 

The disoriented pilot will pull back on the controls, tightening the spiral and increasing the loss of altitude. 

(d)  Somatogravic illusion. 

A rapid acceleration during takeoff can create the illusion of being in a nose 

up attitude. The disoriented pilot will push the aircraft into a nose low, or dive attitude. A rapid deceleration by 

a quick reduction of the throttles can have the opposite effect, with the disoriented pilot pulling the aircraft into 

a nose up, or stall attitude. 

(e)  Inversion illusion. 

An abrupt change from climb to straight and level flight can create the illusion 

of tumbling backwards. The disoriented pilot will push the aircraft abruptly into a nose low attitude, possibly 

intensifying this illusion. 

(f)  Elevator illusion. 

An abrupt upward vertical acceleration, usually by an updraft, can create the 

illusion of being in a climb. The disoriented pilot will push the aircraft into a nose low attitude. An abrupt 

downward vertical acceleration, usually by a downdraft, has the opposite effect, with the disoriented pilot pulling 

the aircraft into a nose up attitude. 

(g)  False horizon. 

Sloping cloud formations, an obscured horizon, a dark scene spread with ground 

lights and stars, and certain geometric patterns of ground light can create illusions of not being aligned correctly 

with the actual horizon. The disoriented pilot will place the aircraft in a dangerous attitude. 

(h)  Autokinesis. 

In the dark, a static light will appear to move about when stared at for many seconds. 

The disoriented pilot will lose control of the aircraft in attempting to align it with the light. 

3.  Illusions Leading to Landing Errors. 

(a) 

Various surface features and atmospheric conditions encountered in landing can create illusions of 

incorrect height above and distance from the runway threshold. Landing errors from these illusions can be 

prevented by anticipating them during approaches, aerial visual inspection of unfamiliar airports before landing, 

using electronic glide slope or VASI systems when available, and maintaining optimum proficiency in landing 

procedures. 

(b)  Runway width illusion. 

A narrower-than-usual runway can create the illusion that the aircraft is at 

a higher altitude than it actually is. The pilot who does not recognize this illusion will fly a lower approach, with 

the risk of striking objects along the approach path or landing short. A wider-than-usual runway can have the 

opposite effect, with the risk of leveling out high and landing hard or overshooting the runway. 

8

−

1

−

6 

Fitness for Flight