In flight verification of the inversion illusion

Area of Science:

• Aerospace Medicine
• Human Factors Engineering
• Vestibular System Research

Background:

• Pilot disorientation during flight maneuvers, particularly pushing over (bunting), is a known issue.
• Existing research suggests inconsistencies in pilots' subjective orientation experiences.
• The specific phenomenon of an "inversion illusion" requires further investigation.

Purpose of the Study:

• To investigate the occurrence and characteristics of the "inversion illusion" in pilots and non-pilots.
• To determine the influence of G-force exposure during specific flight maneuvers on perceived orientation.
• To assess whether the sensation of backward rotation is consistently perceived during inversion illusions.

Main Methods:

• Thirteen aircrew and naive subjects were tested in Hawk or Hunter jet training aircraft.
• Subjects performed a standardized maneuver involving acceleration and a push to -1 G.
• Orientation sensations were recorded with eyes closed and sun visor down during the maneuver.

Main Results:

• 14 out of 30 maneuvers induced an "inversion illusion" in 9 out of 13 subjects.
• Sensations varied, including feet-up rotation, indeterminate rotation, and sudden inversion.
• Naive non-pilots (3/3) and pilots (6/8) reported the illusion, while test pilots (0/2) did not.

Conclusions:

• The "inversion illusion" is a verifiable phenomenon experienced during specific flight dynamics.
• The illusion is more prevalent in less experienced pilots and naive individuals.
• The expected sensation of backward rotation during this illusion is often not perceived.