Definition
Approaches to landing in which the aircraft is not on the correct path, speed, configuration, or descent rate by a defined point before the runway. An unstable approach typically shows one or more of the following: airspeed too high or too low, excessive descent rate, off the centerline or glidepath, incorrect flap or gear configuration, or excessive power changes. The accepted corrective action is a go-around.
Plain English
An approach where the aircraft isn't tracking the runway correctly — wrong speed, wrong height, wrong descent rate, wrong configuration, or not lined up — by the time it should be settled and ready to land. The safe response is to break off the approach and try again.
Context Anchor
Encountered during landing training, especially when an instructor is teaching a student when to continue an approach and when to stop the landing attempt.
Derivation
Unstable comes from stable, meaning firm, steady, or not easily moved, with un- meaning not. Approach, in aviation, means the part of the flight where the airplane is coming toward the runway to land. Together, unstable approaches are approaches that are not steady enough to be safely continued to landing.
Why Pilots Care
Unstable approaches are a leading factor in approach-and-landing accidents; recognizing them early allows a timely go-around decision.
Grounding Statement
If the airplane still needs big corrections close to the runway, the approach is not settled enough to treat as a normal landing.
Intuition Check
Unstable does not mean the airplane is falling out of the sky or that the pilot has lost control. In this context, it means the approach is outside safe, steady landing limits and should be corrected promptly or abandoned.
Example Sentence 1
The instructor pointed out that the airplane was still 20 knots fast and high on glidepath at 400 feet, making it an unstable approach that called for a go-around.
Example Sentence 2
Instructors teach pilots to call out unstable approaches early so they can break the habit of forcing a landing.