Definition
A phase of flight, defined in GPS receiver operation, that covers arrival and departure activity in the area surrounding an airport. During terminal operations, the GPS automatically tightens its course deviation sensitivity from the en route value (typically 5 NM full-scale) to a terminal value (typically 1 NM full-scale), giving more precise course guidance as the aircraft maneuvers near the airport.
Plain English
The part of a flight where you are flying near an airport to depart from it or arrive at it, rather than cruising between airports. When the GPS detects you are in this phase, it switches to a more sensitive setting so small course errors show up clearly on the display.
Context Anchor
Seen in GPS approval, receiver modes, and IFR departure or arrival discussions near an airport.
Derivation
Terminal comes from the Latin terminus, meaning 'end' or 'boundary.' In aviation it refers to the end points of a flight -- the airport areas where flights begin and finish -- as opposed to the en route portion in between.
Why Pilots Care
Knowing the GPS has shifted into terminal mode tells the pilot that course deviation indications are now more sensitive. A needle deflection that would have meant a wide deviation en route now represents a much smaller error, which matters for staying on procedure tracks near the airport.
Intuition Check
Terminal does not mean only the airport building or only the end of the flight. Here it means the airport-area phase of flight used for departures and arrivals.
Example Sentence 1
As the aircraft approached within 30 NM of the destination, the GPS transitioned from en route to terminal operations and the CDI sensitivity tightened.
Example Sentence 2
During terminal operations the pilot used the GPS to follow the arrival route into the airport traffic pattern.