Why isn't there a geofence FLOOR?

I see someone brought this up in 2014:

I’d love to know that if I set a minimum altitude…based on GPS or the barometer, that the copter would not fly below that altitude…would really help when doing flight maneuvers of some kinds (with PLANE as well of course), while doing photography, etc…and ESPECIALLY when flying over water as the consequences of going too low are so high.

Probably 90%(?) of crashes happen when hitting something on the ground or close to the ground (“controlled (or semi-controlled) flight into terrain” as pilots call it)…how nice it would be to set a FLOOR so the copter/plane would not go below a fixed altitude. A “hard deck” as it were.

Or maybe there IS a way to do this with some kind of parameter or, say, via telemetry to a Taranis radio that would change a flight mode or command a climb, etc (but I’d like the flight controller to be able to save itself in case of radio failure)? Or maybe I can use a SONAR or LIDAR to set a floor? Still, I don’t see a way to set a FLOOR in any parameter.

That said I’m no expert. :slight_smile:


There is a minimum altitude option for geofencing. See here for details: https://ardupilot.org/plane/docs/geofencing.html#setting-up-geo-fencing

Copter does not have this parameter.
This parameter is plane only.

I did a PR a while ago adding this exact feature: https://github.com/ArduPilot/ardupilot/pull/7111
But one part of that code was hacky and I did not have the time to pursue it again. Feel free to rebase it on master and improve it.

BUMP for a good safety feature. Thanks…