SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/ifr-leans-illusion

You slowly enter a bank, then correct it abruptly. What does your inner ear tell you?

The leans: a feeling of banking the opposite way.

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  1. That you are climbing
  2. That you are perfectly level
  3. That you are banking the opposite way ✔

Why: A bank entered too slowly does not stir the fluid in the inner ear. The abrupt correction does, so you feel banked the other way and may roll back into the original bank. Trust the attitude indicator.

Huh, didn't know that: The semicircular canals sense angular acceleration, while the otolith organs sense linear acceleration and gravity.

The dad joke
The leans: when your inner ear and your instruments disagree, believe the instruments.
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References

Answer: That you are banking the opposite way. A bank entered too slowly does not stir the fluid in the inner ear. The abrupt correction does, so you feel banked the other way and may roll back into the original bank. Trust the attitude indicator.

  1. FAA Instrument Flying Handbook (FAA-H-8083-15B) www.faa.gov/sites/faa.gov/files/pilots/FAA-H-8083-15B.pdf
    An abrupt correction of this attitude sets the fluid in motion, creating the illusion of a banked attitude to the right.
    Checked 2026-10-10.
  2. FAA Aeronautical Information Manual 8-1 Medical Facts for Pilots www.faa.gov/air_traffic/publications/atpubs/aim_html/chap8_section_1.html
    Spatial disorientation from these illusions can be prevented only by visual reference to reliable, fixed points on the ground or to flight instruments.
    Checked 2026-10-10.

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Test yourself in the game

FlyingWhich illusion can make a pilot in a long steady turn pull back and tighten a descending spiral?FlyingAfter a long turn you look down at a chart and suddenly feel the airplane turning on another axis. What illusion is this?FlyingRapid acceleration on takeoff in clouds can feel like what attitude?

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