Reference

Terrain-following radar (TFR) is a military aerospace technology that allows a very-low-flying aircraft to automatically maintain a relatively constant altitude above ground level and therefore make detection by enemy radar more difficult. ... Use in strike aircraft Advantages and disadvantages. Terrain following radar is primarily used by ...

Terrain-following radar (TFR) is a military aerospace technology that allows a very-low-flying aircraft to automatically maintain a relatively constant altitude above ground level and therefore make detection by enemy ... Use in strike aircraft Advantages and disadvantages. Terrain following radar is primarily used by military strike aircraft ...

Terrain-following radar (TFR) is a military aerospace technology that allows a very-low-flying aircraft to automatically maintain a relatively constant altitude above ground level and therefore make detection by enemy radar more difficult. The height of the top of any particular feature relative to the aircraft can then be calculated through h = H - R sin φ, where H is the altitude over the ground measured by the radio altimeter, φ is the angle and R the range measured by the radar, with h being the resulting height of the object over the current flight path.[8] The clearance between the aircraft and terrain is then H - h.[9]