Definition
Information transmitted from a ground-based station up to an aircraft in flight, typically as part of a navigation, landing, or surveillance system. In the context of approach guidance systems such as the Microwave Landing System (MLS), ground-to-air data includes signals and digital messages sent from ground equipment to the aircraft's onboard receiver to support azimuth, elevation, and approach guidance.
Plain English
Information sent up from equipment on the ground to an aircraft flying overhead. The aircraft's instruments use this incoming information to know things like its position relative to the runway during an approach.
Context Anchor
Seen in instrument approach guidance discussions, especially where a ground system sends navigation and approach information to the aircraft.
Derivation
The term simply describes the direction of the data flow: from the ground up to the aircraft. The opposite is air-to-ground data, which travels from the aircraft down to a ground station.
Why Pilots Care
Supplies critical navigation updates that keep the aircraft aligned with the runway when onboard equipment alone is insufficient.
Intuition Check
Do not think of “data” here as internet service or a general computer file. Here it means specific approach information broadcast by ground equipment for the aircraft to use.
Example Sentence 1
The MLS ground station sends ground-to-air data that the aircraft's receiver uses to compute the approach path.
Example Sentence 2
During the missed approach, updated ground-to-air data allowed the crew to re-establish the proper heading.