Definition
A feature on an electronic altimeter display, typically shown as a vertical bar or arrow alongside the altitude tape, that visually indicates the direction and rate of altitude change over the next several seconds based on the aircraft's current vertical speed.
Plain English
A small marker on the altimeter that shows which way your altitude is heading, and roughly how fast, so you can see at a glance whether you are climbing, descending, or holding level.
Context Anchor
Seen on electronic flight displays near the altimeter tape during instrument flying and straight-and-level flight practice.
Why Pilots Care
Provides instant feedback that helps a pilot correct unintended climbs or descents before altitude deviation becomes significant.
Analogy
It is like a short preview line showing where you will be if you keep moving the same way for a few more seconds.
Intuition Check
Do not read it as the altitude you selected or the altitude the airplane will automatically hold. It is only a short-term prediction based on what the airplane is doing right now.
Example Sentence 1
As he approached 5,000 feet, he watched the altitude trend indicator shrink and began reducing his climb rate to capture the assigned altitude smoothly.
Example Sentence 2
With the altitude trend indicator steady, the pilot confirmed the aircraft was maintaining the assigned IFR altitude.