Definition
A type of RNAV path-and-terminator leg that defines a geodesic (great-circle) flight path between two named fixes, terminating at the second fix. The TF leg is the preferred straight-line leg type in RNAV procedure coding because it specifies both the path to fly and a defined endpoint, allowing precise, repeatable navigation between waypoints.
Plain English
A straight-line segment of an RNAV procedure that goes from one named point to another. The aircraft follows a fixed track between the two fixes and stops tracking when it reaches the second one.
Context Anchor
Seen in instrument approach procedure coding and in GPS or flight-management-system flight plan legs.
Derivation
The name describes exactly what the leg does: the aircraft follows a defined track until it reaches a fix. 'Track' here means the path over the ground between two points, not the aircraft's heading.
Why Pilots Care
Allows precise compliance with published routes, maintaining obstacle clearance and procedure accuracy during instrument operations.
Grounding Statement
For a TF leg, the important line is the aircraft's path over the ground to the fix, not the direction the nose happens to point.
Intuition Check
Track does not mean the direction the nose is pointing; it means the path over the ground. Fix does not mean a repair; it means a named navigation position. Leg does not mean a body part; it means one segment of a route or procedure.
Example Sentence 1
Most of the legs in this RNAV approach are TF legs, so the aircraft will fly straight from each fix to the next.
Example Sentence 2
The aircraft flew the TF leg to reach the final approach fix before turning inbound.