HALO (high-altitude low-opening) parachuting is an insertion technique used exclusively by Special Forces. Drops are made from as 36,000 feet, so that aircraft can evade detection or blend into commercial aviation lanes. At these altitudes, temperatures are well below zero and oxygen equipment is required. HALO insertions are usually performed by small squads, who must keep close together during the drop. The low temperatures, need for breathing equipment and the heavy loads of gear usually required for a HALO jump make it extremely dangerous: icing and shattering of equipment as well as sudden blackouts from hypoxia are real dangers.