Definition
The path that an aircraft follows through the air, described in three or four dimensions — laterally (left/right), vertically (up/down), longitudinally (along track), and often with a time component indicating when the aircraft will be at each point.
Plain English
The route the aircraft is actually flying or is predicted to fly through the sky, including where it is, where it's going, how high it is at each point, and when it will get there.
Context Anchor
Seen in discussions of aircraft movement, flight paths, navigation, and how an aircraft or object moves after a control input or launch.
Derivation
From Latin trajectoria, meaning 'thrown across.' Originally used for the path of a projectile after it was launched. In aviation, it carries the same idea — the path traced through space — but extended to include time and altitude, not just a curve through the air.
Why Pilots Care
Pilots use trajectory awareness to maintain safe clearance from terrain, weather, and traffic while managing fuel and performance.
Intuition Check
Trajectory does not mean only a planned route on a chart. It means the actual path something follows as it moves.
Example Sentence 1
The flight management system computed a descent trajectory that satisfied the crossing restriction at the arrival fix.
Example Sentence 2
During the missed approach, the crew followed the published trajectory to rejoin the arrival.