electricity pylons to being present. Over populated areas with tall radio transmission towers, an altitude of AGL applies. Height above ground level Height above ground level (AGL) in NOE and low flying generally vary with the aircraft speed, aircraft maneuverability and the ruggedness of the terrain. Helicopters are capable of flying with no more than a few feet of clearance below the helicopter's skids or wheels. Fast jets are more constrained and at a typical low-flying speed of , is not unusual and is possible in relatively flat terrain. Power wires are a danger to all aircraft flying at low level and "wire strikes" are common, such as the Cavalese cable car disaster. Special maps are produced that plot the routes of these wires but these are difficult to keep up-to-date, especially for foreign/enemy countries. Pilots are trained to scan for the pylons or power-poles that support these wires, because they can be seen at a distance where the wires themselves cannot. See also Low flying military training Low-altitude parachute-extraction system Radar altimeter Radar horizon Sea skimming (missiles) Terrain-following radar References Aerial maneuvers Aerial warfare tactics Low flying