Definition
An air traffic management approach in which an aircraft's expected path through the airspace system — its 4D trajectory in latitude, longitude, altitude, and time — is shared, agreed upon, and managed between the pilot, the operator, and air traffic control. Decisions about routing, spacing, and sequencing are made against this agreed trajectory rather than by issuing tactical instructions step by step.
Plain English
A way of running air traffic where each flight has an agreed plan that includes not just where it will fly, but exactly when it will be at each point. Controllers and pilots work to keep the aircraft on that plan instead of giving and taking many short instructions along the way.
Context Anchor
Seen in FAA air traffic and modernization discussions, especially where the AIM describes how future traffic flow is planned and managed.
Derivation
Trajectory comes from the Latin trajectus, meaning 'thrown across' — the path an object takes through space. In TBO, the trajectory adds time to that path, so the flight is described as a moving point on a 4D track rather than just a route on a chart.
Why Pilots Care
TBO reduces delays, holding patterns, and fuel burn while enabling more reliable arrival times through precise coordination of aircraft movements.
Grounding Statement
Picture an aircraft approaching busy airspace: TBO is the system planning not only its route, but also where it should be at certain times.
Intuition Check
Do not read TBO here as Time Between Overhaul. In this AIM glossary entry, TBO means Trajectory Based Operations, and “trajectory” includes timing, not just the shape of the flight path.
Example Sentence 1
Under Trajectory Based Operations, the controller cleared the flight to maintain its filed speed and altitude so it would meet the agreed crossing time at the next waypoint.
Example Sentence 2
With TBO in use, the flight followed its assigned trajectory through the terminal area and landed exactly on schedule.