Lock-in Altitude

[Nekoatl]

I'd like a button on the altitude sensor to set the target altitude to the currently measured altitude.  The most obvious use for this would be to simply lock-in the starting altitude, but there would be other creative uses as well, for example, you could program a drone to orbit the planet once at a given altitude, then drop until it hits the tolerance limit, lock-in the new altitude, and repeat the process to gradually work towards the center breadth-first style.