Definition
A position, configuration, or flight condition of the aircraft that was not intended by the flight crew and that reduces safety margins. Examples include unintended deviations from assigned altitude, heading, or airspeed; incorrect aircraft configuration for the phase of flight; and aircraft attitudes or energy states outside normal operating parameters.
Plain English
The airplane has ended up somewhere, in some configuration, or doing something the pilots did not want. It is not yet an accident, but it is a situation that needs to be recognised and corrected before it gets worse.
Context Anchor
Used in safety training, upset prevention and recovery training, approach briefings, and flight debriefs when discussing how a normal flight can drift into an unsafe condition.
Why Pilots Care
Left uncorrected, an undesired aircraft state can rapidly develop into loss of control or an accident.
Analogy
It is like a car entering a curve too fast while drifting out of its lane. Nothing has crashed yet, but the situation is already outside the safe plan and needs immediate correction.
Grounding Statement
A typical example is being low, fast, and not properly set up while approaching the runway.
Intuition Check
Do not read “undesired” as merely “not ideal.” In this term, it means the aircraft condition has moved far enough from the intended condition that safety margins are reduced.
Example Sentence 1
After being distracted by a radio call, the crew noticed they had climbed 300 feet above their assigned altitude -- an undesired aircraft state they corrected immediately.
Example Sentence 2
After a late runway change, the aircraft entered an undesired aircraft state with an excessive bank angle.