Definition
A graphical indicator on a glass-cockpit Primary Flight Display (PFD) that projects, as a curved line or arc extending from the aircraft symbol on the heading indicator or horizontal situation indicator, the heading the aircraft will reach in a set time (typically six seconds) if the current rate of turn is maintained.
Plain English
A short curved line on the heading display that shows where the aircraft's nose will be pointing in a few seconds if it keeps turning at the current rate.
Context Anchor
Seen on glass cockpit flight displays during turns, especially while watching the heading display in instrument flight.
Derivation
Trend' comes from Old English 'trendan,' meaning to turn or roll. A trend vector points in the direction things are heading — here, where the heading will be a few seconds from now.
Why Pilots Care
It gives immediate visual feedback on turn rate so the pilot can maintain a standard-rate turn or adjust promptly without diverting attention from the attitude indicator.
Grounding Statement
During a turn, the vector moves ahead of the current heading and gives the pilot a quick picture of where the airplane is about to point if nothing changes.
Intuition Check
Do not read “trend” as a suggestion or command. Here it means a prediction based on the aircraft’s present turn, not an instruction to turn that way.
Example Sentence 1
As she rolled into the turn, she watched the turn rate trend vector extend toward 270° and began rolling out as it touched her assigned heading.
Example Sentence 2
As the heading approached the final approach course, the turn rate trend vector showed the rollout would occur exactly on the desired track.