Definition
A small auxiliary control surface attached to the trailing edge of a stabilator that moves in the same direction as the stabilator. Its purpose is to increase the control force the pilot feels and to prevent the stabilator from being over-controlled. It also functions as a trim tab when adjusted by the pilot.
Plain English
A small flap on the back edge of a stabilator that moves the same way the stabilator moves. It deliberately makes the controls feel heavier so the pilot does not move the stabilator too far too easily.
Context Anchor
Seen during tail inspection, control-surface rigging, and discussions of stabilator-equipped aircraft.
Derivation
The name combines 'anti' (against) with 'servo' (a device that assists movement). A normal servo tab helps the pilot move a control surface. An antiservo tab does the opposite — it works against easy movement, adding resistance so the controls do not feel too light.
Why Pilots Care
Prevents over-sensitive pitch response on aircraft that use a stabilator instead of a fixed horizontal stabilizer and elevator.
Intuition Check
Do not think of “antiservo” as meaning the tab stops movement. It still moves; it moves in a way that adds control feel instead of helping the surface move more easily.
Example Sentence 1
During the preflight inspection, the pilot checked that the antiservo tab on the stabilator moved freely and was secure.
Example Sentence 2
With the antiservo tab installed, the pilot felt increased resistance when pulling the nose up, improving pitch stability at cruise speed.