leans
A dangerous sensory illusion where the pilot of an aircraft believes themselves to be in a bank when they are actually wings-level, or vice-versa, often resulting in spatial disorientation and loss of control of the aircraft.
Example
“If you don't use your flight instruments when flying in cloud, you can easily get the leans and enter a fatal graveyard spiral.”
Where this comes from
This definition is adapted from “leans” on Wiktionary, by its contributors, published under CC BY-SA 4.0. This page is published under the same licence.