Terrain awareness
iNav knows how high the drone is above its home point, not above the ground under it. Take off in a valley, fly towards a hill, and “60 m” can really mean 15 m above the slope. Wizzo works out height above ground (AGL) from elevation data:
AGL = ground height at home + height above home − ground height under the drone
AGL shows under the HUD’s altitude tape and in the map’s GPS widget.
Warnings
Section titled “Warnings”| Warning | When |
|---|---|
| ABOVE 120 m AGL | Above the ceiling. 120 m is CASA’s standard limit. |
| LOW · 12 m AGL | Below the minimum height while flying. |
| TERRAIN AHEAD · 140 m | The ground along the drone’s track, within the look-ahead time, would bring it below the minimum. |
| NO TERRAIN DATA | No elevation data saved for where the drone is. |
The low and terrain-ahead warnings only show once the drone is flying, so sitting armed on the pad doesn’t set them off. Set the ceiling, minimum height and look-ahead time under Setup › Terrain.
Offline
Section titled “Offline”Elevation data within 3 km of you and of home downloads automatically while you have signal, and stays on the phone. Before heading somewhere without coverage, tap Download 6 km around me in Setup › Terrain.
How accurate is it?
Section titled “How accurate is it?”The data is about 30 m resolution, with a few metres of height error, more on steep slopes. In some places it includes trees and buildings. Treat AGL as a guide for warnings, not for flying close to the ground. For terrain following, use a rangefinder on the drone.