There is actually an ingame radar altimeter of a sorts in FA but sadly the game producers (Brett Iverson and Crew) were not smart enough to realize it...
When the terrain turns off at 37,500 ft it turns back on if you fly over elevated terrain by taking that elevation and adding to to the 37,500 ft limiter.
As an example the terrain will turn off at 37,501 ft unless you are flying at terrain that is over 1 foot tall... Lets say you are flying over a 5000 ft mountain peak and your aircraft altitude is at 52,499 ft. The terrain will turn back on until you clear that peak and the terrain drops in height. That means the game is always figuring your actual altitude above the ground and that number is accessible somewhere in the original assembly code, but they didn't think to make it available to player to display in a MFD Window as Radar Altimeter Height...
So its all there they just never accessed it... Makes me sad...
