Originally Posted by Lafyar Cokov
Certainly for flying over the Jungle canopy at very low level (in a military helicopter), the radalt generally locks onto the tree tops but one does have the occasionaly spike down to the ground for no apparent reason.
Thanks, much as I expected... The beam from a modern rad alt is only about 20° or less, so any small clearing at the low level you're talking about would cause it to 'latch on' to the ground level momentarily.