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Parachuting, or skydiving, is a method of exiting an aircraft and returning to Earth with the aid of gravity, then slowing down during the last part of the descent by using a parachute. It may involve more or less free-fall, a time during which the parachute has not been deployed and the body gradually accelerates to terminal velocity. Andre-Jacques Garnerin was the first to make successful descents using a canvas canopy from a small basket tethered beneath a hot-air balloon. The first intentional freefall jump with a ripcord-operated deployment is credited to Leslie Irvin in 1919. The military developed parachuting technology as a way to save aircrews from emergencies aboard balloons and aircraft in flight, and later as a way of delivering soldiers to the battlefield. Early competitions date back to the 1930s, and it became an international sport in 1952. ==Common Uses== Parachuting is performed as a recreational activity, a competitive sport, and is widely considered an extreme sport due to the risk involved. Modern militaries utilize parachuting for the deployment of airborne forces, and special operations forces commonly employ parachuting, especially free-fall parachuting, as a method of insertion. Occasionally forest firefighters, known as "smokejumpers" in the United States of America, use parachuting as a means of rapidly inserting themselves near forest fires in especially remote or otherwise inaccessible areas. Manually exiting an aircraft and parachuting to safety has been widely used by aviators (especially military aviators), aircrew, and passengers to escape an aircraft that could not otherwise land safely. While this method of escape is relatively rare in modern times, it was commonly used in World War I by military aviators, and utilized extensively throughout World War II. In modern times, the most common means of escape from an aircraft in distress is via an ejection seat system. Said system is usually operated by the pilot, aircrew member, or passenger, by engaging an activation device manually. In most designs, this will lead to the seat being propelled out of and away from the aircraft carrying the occupant with it, by means of either an explosive charge or a rocket propulsion system. Once clear of the aircraft, the ejection seat will deploy a parachute, although some older models entrusted this step to manual activation by the seat's occupant. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Parachuting」の詳細全文を読む スポンサード リンク
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