Carrier-based aircraft are military aircraft designed specifically for operations from aircraft carriers. The term is generally applied only to fixed-wing aircraft, as naval helicopters are able to operate from a wider variety of aviation-capable ships. Carrier-based aircraft must be relatively sturdy to withstand demanding carrier operations. They must be able to launch in a short distance and be sturdy and flexible enough to come to a sudden stop on a pitching deck; they typically have robust folding wing mechanisms that allow higher numbers of them to be stored in below-decks hangars. These aircraft are designed for many purposes including air-to-air combat, surface attack, submarine attack, search and rescue, materiel transport, weather observation, reconnaissance and wide area command and control duties.