Definition
An RNAV path and terminator leg that begins at a defined fix, follows a specified track (course) outbound from that fix, and ends when the aircraft has flown a specified distance from the fix. The leg terminates based on along-track distance from the originating fix, not on reaching another waypoint or altitude.
Plain English
Fly outbound from a named point on a set heading-line, and stop flying that line once you are a specific number of miles from that point. The starting point and the distance flown from it define when the leg ends.
Context Anchor
Seen in RNAV instrument procedure design and flight management system leg descriptions, especially when learning how path-and-terminator legs define the route an aircraft is expected to fly.
Derivation
The two-letter codes used for path and terminator legs come from ARINC 424, the industry standard that tells navigation databases how to describe each segment of a procedure. 'FC' stands for 'Fix to Distance,' meaning the path is built from a starting fix and ends after a set distance.
Why Pilots Care
It guarantees the aircraft follows the exact route and distance the procedure designer intended for safe obstacle clearance and traffic flow.
Grounding Statement
Picture leaving a marked point on a map, following one exact line for a set number of miles, and then starting the next instruction.
Intuition Check
Do not read “fix” as something being repaired. In instrument procedures, a fix is a named position in space. Do not read “distance” as a rough estimate. Here it is the defined point where that leg ends.
Example Sentence 1
The departure procedure uses an FC leg that tracks 090 from WAVES for 6 NM before turning on course.
Example Sentence 2
The missed approach begins with an FC leg from the runway fix along 270 degrees for four nautical miles.