Definition
A GPS receiver mode in which the course deviation indicator (CDI) becomes more sensitive as the aircraft approaches a destination airport. Within 30 nautical miles of the destination, full-scale CDI deflection automatically tightens from the en route value of 5 NM to 1 NM, allowing more precise tracking during the terminal phase of flight.
Plain English
When you get within 30 miles of your destination airport, the GPS automatically makes the left/right needle on your course indicator more responsive, so small drifts off course show up sooner and you can fly a tighter, more accurate track.
Context Anchor
Seen during IFR departures, arrivals, and other terminal-area operations when the aircraft is near the departure or destination airport.
Derivation
"Terminal" comes from the Latin terminus, meaning "end" or "boundary" -- the airspace at the end of a flight, near the airport. "Sensitivity" describes how strongly the CDI needle reacts to a given amount of off-course distance. Together: the needle's responsiveness during the terminal phase.
Why Pilots Care
The tighter scaling improves precision on approaches but demands more accurate flying because deviations are magnified.
Grounding Statement
As the airplane gets close to the airport, the navigation scale tightens so smaller left-or-right errors show up more clearly.
Intuition Check
Terminal does not mean the passenger building here; it means the airport-area part of the flight. Sensitivity does not mean the equipment is fragile; it means how tightly the course display is scaled.
Example Sentence 1
As we crossed 30 miles from the destination, the GPS transitioned to terminal sensitivity and the CDI tightened to 1 NM full-scale.
Example Sentence 2
The pilot reduced course corrections after the system reverted from terminal sensitivity to en route scaling on the missed approach.