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SESK: Stuff Everyone Should Know · sesk.info/pilot-the-leans-illusion

What causes the flight illusion called the leans?

Snapping level after a slow, unnoticed turn.

  1. Staring at a single light at night
  2. A sudden climb after takeoff
  3. Leveling the wings after a slow, unnoticed turn ✔

Why: The inner ear cannot sense a roll slower than about 2 degrees per second. If you drift into a gentle bank and then roll level, your body feels like it is banking the other way. Trust the instruments.

Huh, didn't know that: The leans is the most common illusion during flight.

The dad joke
Why did the Leaning Tower of Pisa skip flight school? It already had the leans.
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Sources

  1. FAA Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 17 https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/faa-h-8083-25c.pdf
  2. Aeronautical Information Manual 8-1-5, Illusions in Flight https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap8_section_1.html

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