Definition
A horizontal tail surface whose angle of incidence can be changed in flight to trim the aircraft for varying load and speed conditions. Instead of using a fixed horizontal stabilizer with a movable trim tab on the elevator, the entire stabilizer pivots, typically driven by a jackscrew, to set the pitch trim of the airplane.
Plain English
It is the small wing at the tail that can tilt up or down as a whole. By tilting the whole tail surface, the pilot trims the airplane so it flies level without having to hold pressure on the controls.
Context Anchor
Seen in aircraft control, trim, and weight-and-balance discussions, especially when loading changes how much nose-up or nose-down force the airplane needs to balance.
Derivation
“Stabilizer” comes from “stable,” meaning steady or not easily disturbed. In this term, it points to the tail surface that helps keep the airplane steady in pitch; “adjustable” tells you that the surface’s angle can be changed.
Why Pilots Care
Allows the pilot to set a stable pitch attitude for hands-off flight at different speeds, weights, or power settings.
Intuition Check
Do not assume this means only the elevator moves. On aircraft with an adjustable horizontal stabilizer, the stabilizer itself changes angle to help balance the airplane.
Example Sentence 1
After leveling off in cruise, the pilot trimmed the adjustable horizontal stabilizer to relieve the back pressure on the yoke.
Example Sentence 2
The mechanic verified the full travel of the adjustable horizontal stabilizer during the preflight inspection.