Definition
An air traffic management approach in which each aircraft is managed as a four-dimensional flight path -- latitude, longitude, altitude, and time -- shared between the aircraft and air traffic control. Instead of issuing tactical instructions to keep aircraft separated, controllers and the system agree on a planned trajectory for each flight and manage the operation by adjusting that trajectory when needed.
Plain English
Air traffic is run by agreeing in advance on the exact path each aircraft will fly, including when it will be at each point along the way, rather than the controller giving heading, altitude, and speed instructions as the flight unfolds.
Context Anchor
Seen in FAA NextGen discussions about future air traffic control, flight planning, and more predictable use of busy airspace.
Derivation
Trajectory comes from the Latin trajectoria, meaning the path of something moving through space. In aviation, it is used in a precise sense: not just where the aircraft will go, but when it will be at each point along the route. Operations here means the day-to-day running of air traffic, so Trajectory Based Operations means running air traffic around agreed flight paths in time and space.
Why Pilots Care
Enables smoother routing, lower fuel use, fewer delays, and higher overall system capacity.
Analogy
It is like several cars using navigation apps that not only know the roads they will take, but also when each car is expected to reach each intersection. The system works better when everyone’s planned path and timing are visible.
Grounding Statement
Picture a flight plan that is not just a line on a map, but a timed path showing where the aircraft should be throughout the flight.
Intuition Check
Do not read “trajectory” here as only the curved path of a falling object. In this FAA context, it means the aircraft’s planned path through the air, including timing.
Example Sentence 1
Under Trajectory Based Operations, the crew is expected to meet the assigned time at the arrival fix within a tight tolerance, not just fly the route in the correct order.
Example Sentence 2
Trajectory Based Operations let dispatch and ATC adjust a route in real time while preserving the agreed arrival time.