Definition
An unintended flight condition in which an airplane is at a pitch attitude greater than 25 degrees nose up, more than 10 degrees nose down, banked more than 45 degrees, or flying within those limits but at airspeeds inappropriate for the conditions.
Plain English
A situation where the airplane has departed from normal flight — pointed too far up or down, rolled too far to one side, or flying at a speed that doesn't match what it's doing — and the pilot needs to recover it back to normal flight.
Context Anchor
Seen in upset prevention and recovery training, loss-of-control discussions, instrument training, and accident-prevention material.
Derivation
"Upset" comes from the everyday sense of something being knocked out of its normal position. In aviation it carries that same plain meaning: the airplane has been knocked out of normal, controlled flight and needs to be set right.
Why Pilots Care
Failure to recognize and recover from an upset can quickly lead to loss of control, one of the leading causes of fatal accidents.
Grounding Statement
Picture the airplane suddenly nose-low with the wings steeply tilted after turbulence or a distraction; that is the kind of situation meant by an airplane upset.
Intuition Check
Upset does not mean the pilot is emotionally upset. Here it means the airplane itself has unintentionally departed from the attitude or speed needed for the situation.
Example Sentence 1
After encountering severe wake turbulence, the airplane rolled past 60 degrees of bank, meeting the definition of an airplane upset.
Example Sentence 2
Wake turbulence from a preceding aircraft can trigger an airplane upset if the pilot does not react promptly.