Plain English Meaning

A little pointer on the altimeter that you can move to mark an altitude you want to remember, so you can see at a glance when you are reaching it.

Full Definition

A small movable marker on the face of an altimeter that the pilot can set to a chosen altitude as a visual reference. It does not change how the altimeter measures altitude; it simply provides a quick visual cue showing a target altitude such as a level-off, decision altitude, or minimum descent altitude.

Context Anchor

Seen on cockpit altimeters and altitude displays, especially during instrument flying, approaches, climbs, descents, and altitude changes assigned by air traffic control.