Definition
The cockpit instrument that displays the aircraft's altitude above a selected pressure reference, typically mean sea level when set to the local altimeter setting. It senses changes in atmospheric pressure through a static port and converts those pressure changes into an altitude reading shown on its face.
Plain English
The dial in the cockpit that tells you how high you are flying. It works by measuring the air pressure outside the aircraft and turning that into an altitude number you can read.
Context Anchor
Seen on the instrument panel and in instrument-flying references when checking whether the aircraft is holding the assigned altitude.
Derivation
From Latin altus (high) plus the suffix -meter (a measuring device). 'Indicator' comes from Latin indicare, to point out. Together: a device that points out how high you are.
Why Pilots Care
Accurate altitude awareness prevents controlled flight into terrain and ensures compliance with assigned altitudes.
Intuition Check
Do not read “indicator” as a separate warning light here. In this context, it means the altitude display the pilot reads.
Example Sentence 1
During the climb, the pilot scanned the altimeter indicator and leveled off as it reached 6,000 feet.
Example Sentence 2
Before entering the traffic pattern, the pilot set the altimeter indicator to the local altimeter setting and verified the indicated altitude.