Check altitude

Hi,

I try to make a drone who get in space and then come back to land.

I usually use "Visual Script Builder" to make my scripts and it's work fine.
But I want something that isn't possible with this site.

To go down on the planet I shutdown all the engine from my drone.
This to not use too much fuel, and because of the speed bug in gravity.

I need something like "If altitude < 1500m do start all engine".

I have find this script :...

Check altitude