Leans describes a physical sensation caused by what?

• A. A weather phenomenon
• B. A misalignment of instruments
• C. A physical sensation caused by abrupt correction of a banked attitude entered too slowly to stimulate the motion sensing system in the inner ear
• D. A miscalculation of fuel

Answer: (C)

The leans is a vestibular illusion—the brain’s misperception of bank due to how the inner ear detects motion. The semicircular canals sense angular acceleration, not steady tilt. If you enter a bank gradually, the movement may not be enough to trigger a strong sense of turning, so your vestibular system can adapt and you may feel as if you’re level when you’re actually banked. Then, when you correct and roll out abruptly, the sudden angular acceleration stimulates the motion-sensing system and produces a false sensation of a bank or tilting moment. That combination—the bank being entered too slowly to stimulate the inner ear, followed by an abrupt correction—produces the physical sensation described as the leans. Weather phenomena, instrument misalignment, or fuel miscalculations don’t create this vestibular illusion.