Definition
An altimeter that uses a sealed aneroid capsule connected to a small electric servo motor, which drives the indicating pointers and digital counters. As outside static pressure changes, the aneroid expands or contracts; this movement is sensed electrically and amplified to drive the display, giving smoother and more accurate altitude readings than a purely mechanical altimeter.
Plain English
An altimeter where a small motor moves the needles, instead of gears and springs doing the work directly. A pressure sensor tells the motor how to position the display, which makes the reading steadier and more accurate.
Context Anchor
Seen in aircraft instrument systems, especially where altitude information must be displayed accurately or sent to other aircraft systems.
Derivation
‘Servo’ comes from the Latin servus, meaning servant. In engineering, a servo is a small powered device that ‘serves’ a control input by doing the physical work of moving something. Here, the servo motor does the work of driving the altimeter display in response to pressure changes.
Why Pilots Care
Delivers steadier, more accurate altitude information with less lag, supporting safer vertical navigation and reduced risk of altitude deviation.
Intuition Check
Servo does not mean a separate backup altimeter here. It means the altimeter uses a powered follow-up mechanism to move or control the altitude indication.
Example Sentence 1
The aircraft’s servo altimeter held its indication smoothly through the climb, without the small jumps you sometimes see on a mechanical unit.
Example Sentence 2
Before takeoff the crew cross-checked the servo altimeter against the backup unit to confirm both read the field elevation.