Definition
Restrictions on which path and terminator (P&T) combinations a particular RNAV or RNP system is approved to fly. A path and terminator is the two-letter code (such as TF, RF, CF, or VA) that tells the flight management system how to fly a leg of a procedure and where that leg ends. Not every aircraft and avionics combination supports every P&T type, so manufacturers and operators publish limitations identifying which legs the system can execute and which it cannot.
Plain English
Procedures in the navigation database are built from coded leg types that tell the autopilot how to fly each segment and where it ends. Some aircraft systems can fly all of these leg types, and some cannot. Path and terminator limitations spell out which ones your specific equipment is allowed to fly.
Context Anchor
Seen when studying RNAV instrument procedures and how procedure legs are stored and flown by GPS or other panel navigation systems.
Derivation
Path' refers to the shape of the flight segment (straight, curved, heading, course). 'Terminator' comes from Latin terminare, meaning 'to end' -- it marks where the leg finishes (at a fix, at an altitude, at an intercept). Together they describe how a leg is flown and how it concludes.
Why Pilots Care
Recognizing these limitations explains why certain procedure legs are coded a specific way and helps avoid database or FMS mismatches during flight.
Grounding Statement
A path and terminator leg is one piece of an instrument procedure: fly this path until this specific ending point or condition occurs.
Intuition Check
Do not read “terminator” as a device or as the end of the whole procedure. Here it means the point or condition that ends one route segment. Do not read “limitations” as general pilot limitations. Here it means limits in how certain procedure segments can be coded, shown, or flown by navigation equipment.
Example Sentence 1
Before accepting the RNAV arrival, the crew checked the AFM and confirmed their FMS had no path and terminator limitations affecting the RF legs in the procedure.
Example Sentence 2
Due to path and terminator limitations, the procedure could not end the course-to-fix leg with an altitude constraint in that segment.