Arducopter 4.3.X does not arm due a “Terrain Data Missing” error caused by a bug not present until 4.2.X. We use this function for over 3 years with no problems. Switching back to V4.2.X all works fine. All our missions use waypoints with “Terrrain” altitude type.
This error is happening with working rangefinder (radar) and TERRAIN_ENABLE,0. The Rangefinder has a working height of 20m, so “Data Missing” should happen only after I pass 20m. Please correct the code. We do not load terrain data since we fly very low (crop sprayers) and we need radar information to follow terrain.