Unmanned aerial vehicle
Unmanned aerial vehicles (UAVs) are gaining popularity for observing dangerous areas or to reduce costs. A special type of UVA, the High Altitude Long Endurance (HALE) vehicle, can bridge the gap between manned survey aircraft and spacecraft or satellites. Typically, a HALE is a remotely operated aircraft of ultra-light weight and load that flies for months at altitudes of around 20 km.