Autokinesis

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Autokinesis is a visual illusion. It can occur under certain conditions, especially on dark nights in areas with few visual cues (such as lights or other illuminated objects or landmarks). When a small, dim, and fixed light source remains within visual range for an extended period of time, this phenomenon can occur, making it appear as if the light source were moving. This visual illusion can be of particular danger to pilots at night. In addition, it is possible that this illusion may account for some supposed UFO sightings in which witnesses may see an isolated light, such as a bright star or planet, seeming to move erratically around. (see Identified flying object)

Autokinesis and Countermeasures for Pilots

A stationary light stared at for 6 to 12 seconds in the dark will appear to move. This phenomenon can cause considerable confusion for pilots, especially those flying in formation or rejoining on a refueling tanker at night.

To prevent, or overcome this phenomenon, the pilot should:

• Shift their gaze frequently to avoid prolonged fixation on light sources.
• Attempt to view a target with a reference to stationary structures or landmarks.
• Make eye, head, and body movements to eliminate the illusion.
• Monitor the flight instruments to prevent or resolve any perceptual conflict.

References

• U.S. Air Force (2000). Flying Operations, Instrument Flight Procedures. Air Force Manual 11-217. Volume 1, 29 December 2000.
• Fundamentals of Aerospace Medicine, second edition, by Roy L. DeHart. Port City Press, 1996.