Definition
A stored digital map of terrain elevations used by a GPS-based navigation system to compare the aircraft's position and altitude against the height of the ground beneath and around it. The database supplies the elevation data that drives terrain awareness displays and ground-proximity alerts in many modern avionics units.
Plain English
A built-in map of how high the ground is at every point, so the GPS can warn the pilot if the aircraft is getting too close to it.
Context Anchor
Seen in instrument departure and low-visibility operations, especially when discussing terrain awareness during takeoff or climbout.
Derivation
Database comes from the idea of a stored collection of facts the system can look up. Here the facts are terrain elevations — the height of the land — paired with their geographic locations.
Why Pilots Care
It supplies the data that powers terrain warnings, reducing the risk of controlled flight into terrain.
Analogy
It is like having a stored topographic map inside the avionics. The system uses your position on that map to help point out high ground near you.
Grounding Statement
The system does not see terrain directly; it matches your GPS position against stored terrain information.
Intuition Check
Do not assume a GPS terrain database is live radar or real-time vision. It is stored information, so its usefulness depends on the database being correct and current.
Example Sentence 1
Before the cross-country flight through the mountains, the pilot confirmed that the GPS terrain database was current.
Example Sentence 2
During the climb in IMC, the system used the GPS terrain database to generate a terrain caution alert.