Self explainatory, as the title said.
It is not quite hard as the HUD is already present in camera mode 5.
Just create a new part and slap a Decal onto the current altitude indicator present in the virutal cockpit, add the same script and make the Texture. Done. It shouldn't be quite hard to add this feature into the game. But adding this to all aircraft may take some time.
(i think this is only for aircrafts that has PFDs)
