Definition
On an electronic flight display, trend vectors are short magenta or cyan lines projecting from the airspeed and altitude tapes that show what those values will be in six seconds if the current rate of change continues. They give the pilot a visual prediction of where airspeed and altitude are heading, not just where they are now.
Plain English
Small lines on the glass cockpit display that show where your speed and altitude will be a few seconds from now if you keep doing what you are doing.
Context Anchor
Seen on electronic flight displays, especially near the speed scale, altitude scale, and direction display during instrument flying.
Derivation
From 'trend' (the direction something is moving) and 'vector' (a line showing direction and magnitude). Together: a line showing the direction and rate of change.
Why Pilots Care
They let the pilot see and correct trends early, before small changes become large deviations that require bigger inputs.
Grounding Statement
If the altitude trend vector points toward 5,200 feet while you are climbing through 5,000 feet, the display is showing where your altitude is likely to be shortly if the climb continues.
Intuition Check
Do not read “vectors” here as ATC instructions to fly a heading. Trend vectors are display predictions, not commands.
Example Sentence 1
As the airplane climbed through 5,400 feet, the altitude trend vector reached up to 6,000, so the pilot reduced pitch to begin the level-off.
Example Sentence 2
With the airspeed trend vector pointing upward, the pilot lowered the nose slightly to stabilize at the target speed.