Nap-of-the-earth

Nap-of-the-earth (NOE) is a type of very low-altitude flight course used by military aircraft to avoid enemy detection and attack in a high-threat environment.

Using NOE flight, the approach may be undetected; the aircraft "pops up" to attack the target and then turns to escape before the enemy can respond.

The lowest NOE flying is by helicopters because they have lower speeds and more maneuverability than fixed-wing aircraft, particularly fast jets.

Attack helicopters can hide behind trees or buildings, "popping up" with minimum exposure, just enough to use their (rotor mast-mounted) radar or other sensors and launch weapons.

In populated areas with tall radio transmission towers, an altitude of 150 m (490 ft) above ground level applies.