Marginal

No. It's fixed to the same range as the in-cockpit RDA-1 instrument.

Release 1.2.0: Display AGL when gear is down and altitude < 3000m AGL.

That seems like a natural solution (and has the advantage of being easier to implement!)

I tried this and it didn't work so well. Will look at making a setting instead.

Switching at 3,000 ASL could work for planes. Not so good for landers - if you're rapidly approaching a 2,000m ridge on the Mun it would only switch over at 1,000m AGL which doesn't give you much time to start your final burn. I'll look in to whether I can reliably tell a plane from landers. vesselType looks promising, otherwise I could go off whether the command module is a cockpit or not.

I agree that when you’re in level flight between 3,000-5,000m ASL it will be a bit annoying to have the readout flipping back and forth between ASL and AGL modes. But I don’t spend any time in level flight at those altitudes so automatic switching seemed simpler and more attractive to me. Also, I don’t want to display radar altitude above 3,000m since that would go beyond the tech available in the unmodded game. Making it customisable means adding a menu and taking up screen space with a button to bring up the menu, which seemed intrusive for such a basic mod. Doesn’t the Landing Height mod let you manually switch modes if that’s what you want?

This mod automatically switches the altitude readout from ASL to AGL below 3000m. KSP's exterior view shows altitude above sea level ("ASL") at the top of the screen (actually altitude above the deepest point for planets without seas). That's not very useful when you're attempting to land in the dark or trying to conserve fuel by starting your landing burn as late as possible. What you want to see instead is altitude above ground level ("AGL"). Manned command modules are equipped with an RDA-1 radar altimeter which displays AGL for altitudes < 3000m, with more precision for altitudes < 500m. But you have to switch to internal view to see it which is a pain for manned modules and isn't possible at all for unmanned probes: This mod automatically switches the exterior view's altitude readout from ASL to AGL and the digits' colour from black to "navball brown" when your gear is down and your altitude is below 3000m AGL: Note that, like the RDA-1 altimeter, the display shows the altitude of the command module above the ground so when judging your landing you still have to account for the height of fuel tanks, landing legs etc below your command module. Installation Download and extract RadarAltitude-122.zip. Put the "RadarAltitude" folder into your KSP installation's "GameData" folder. Source GitHub. Acknowledgements Joe Patrick's Radar Altimeter for 1.2 which performed a similar function, but which required a hotkey press to switch between ASL and AGL. License Copyright © 2018 Jonathan Harris. Licensed under the GNU Public License (GPL) version 2 or later.