Definition
A graphical line or arrow displayed on an electronic flight instrument (such as a primary flight display) that predicts where a parameter — typically airspeed, altitude, or heading — will be a set number of seconds in the future if the current rate of change continues.
Plain English
A short line on a glass-cockpit display that shows where your speed, altitude, or heading is heading next if you keep doing what you're doing right now.
Context Anchor
Seen on electronic flight displays and moving-map displays, especially when monitoring changes in airspeed, altitude, vertical movement, or aircraft path.
Derivation
‘Trend’ comes from the Old English ‘trendan,’ meaning to turn or roll in a direction. ‘Vector’ comes from the Latin ‘vehere,’ meaning to carry. Together, the term carries the idea of ‘the direction something is being carried toward’ — a useful image for a line that shows where a value is going.
Why Pilots Care
It lets the pilot spot and correct a developing deviation early rather than waiting for the actual value to move outside limits.
Intuition Check
Do not read trend vector as a command to fly somewhere. It is a prediction based on what is happening now, not an instruction and not a guarantee.
Example Sentence 1
As the airspeed trend vector reached the top of the green arc, the pilot reduced power to avoid exceeding maneuvering speed.
Example Sentence 2
Watching the altitude trend vector helped the pilot maintain level flight during the approach.