Definition
A TF leg is an RNAV path/terminator leg type that defines a geodesic (great-circle) track between two specified fixes, terminating at the second fix. The leg is fully defined by its starting fix, ending fix, and the precise track between them, allowing flight management systems to fly a repeatable, predictable course.
Plain English
A TF leg is a straight flight path drawn between two named points on a chart. The aircraft flies from the first point directly to the second, following the exact line between them.
Context Anchor
Seen in GPS-based instrument procedures and in the navigator’s flight-plan or procedure-leg display.
Derivation
The name describes the function directly: 'Track' is the path over the ground, and 'to a Fix' means the leg ends at a defined waypoint. The label tells you exactly what the leg does — fly a track until you reach the fix.
Why Pilots Care
It provides precise, repeatable guidance between waypoints in performance-based navigation without depending on ground radio signals.
Intuition Check
Do not read track as a railroad track or fix as a repair. Here, track means the airplane’s path over the ground, and fix means a named navigation point.
Example Sentence 1
The RNAV approach was built almost entirely from TF legs, giving us the same predictable ground track on every arrival.
Example Sentence 2
On the missed approach the aircraft flies a TF leg to reach the holding fix.