Definition
A radar-based approach service in which a ground controller, watching the aircraft's position on precision radar, gives the pilot continuous voice instructions for heading and descent to bring the aircraft down to a safe landing. A GCA may be a Precision Approach Radar (PAR) approach, which provides both course and glidepath guidance, or an Airport Surveillance Radar (ASR) approach, which provides course guidance only.
Plain English
A landing approach where a controller on the ground uses radar to watch your airplane and tells you over the radio exactly which way to turn and when to descend, so you can land safely even when you can't see the runway until the last moment.
Context Anchor
You may see GCA in approach, airport, or emergency discussions, especially where radar-based help from a controller is available for landing in poor weather.
Derivation
The name describes the service literally: the approach is controlled from the ground rather than flown by the pilot reading their own instruments. Knowing this helps separate it from a normal instrument approach, where the pilot follows published guidance independently.
Why Pilots Care
Provides a reliable way to complete a landing when visibility prevents a visual or standard instrument approach.
Intuition Check
Do not confuse ground control approach with taxi instructions from Ground Control. Here, ground means the guidance comes from a controller on the ground, and approach means the final part of getting to the runway to land.
Example Sentence 1
With the ceiling down to 200 feet and his navigation radio acting up, the pilot requested a GCA and followed the controller's headings and descent calls all the way to the runway.
Example Sentence 2
GCA guidance allowed the aircraft to reach the runway even though the cloud layer was solid down to two hundred feet.