Parachuting

 

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 or may not involve a certain amount of 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 and 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.
Safety

Despite the perception of danger, fatalities are rare. About 21 skydivers are confirmed killed each year in the US, roughly one death for every 150,000 jumps (about 0.0007%).
In the US and in most of the western world skydivers are required to carry two parachutes. The reserve parachute must be periodically inspected and re-packed (whether used or not) by a certificated parachute rigger (in the US, an FAA certificated parachute rigger). Many skydivers use an automatic activation device (AAD) that opens the reserve parachute at a pre-determined altitude if it detects that the skydiver is still in free fall. Depending on the country, AADs are often mandatory for new jumpers, and/or required for all jumpers regardless of their experience level. Most skydivers wear a visual altimeter, and an increasing number also use audible altimeters fitted to their helmet.

Injuries and fatalities occurring under a fully functional parachute usually happen because the skydiver performed unsafe maneuvers or made an error in judgment while flying their canopy, typically resulting in a high speed impact with the ground or other hazards on the ground. One of the most common sources of injury is a low turn under a high-performance canopy and while swooping. Swooping is the advanced discipline of gliding at high speed parallel to the ground during landing.

Changing wind conditions are another risk factor. In conditions of strong winds, and turbulence during hot days the parachutist can be caught in downdrafts close to the ground. Shifting winds can cause a crosswind or downwind landing which have a higher potential for injury due to the wind speed adding to the landing speed.

Another risk factor is that of "canopy collisions", or collisions between two or more skydivers under fully inflated parachutes. Canopy collisions can cause the jumpers' inflated parachutes to entangle with each other, often resulting in a sudden collapse (deflation) of one or more of the involved parachutes. When this occurs, the jumpers often must quickly perform emergency procedures (if there is sufficient altitude to do so) to "cut-away" (jettison) from their main canopies and deploy their reserve canopies. Canopy collisions are particularly dangerous when occurring at altitudes too low to allow the jumpers adequate time to safely jettison their main parachutes and fully deploy their reserve parachutes.

Equipment failure rarely causes fatalities and injuries. Approximately one in 750 deployments of a main parachute result in a malfunction. Ram-air parachutes typically spin uncontrollably when malfunctioning, and must be jettisoned before deploying the reserve parachute. Reserve parachutes are packed and deployed differently; they are also designed more conservatively and built and tested to more exacting standards so they are more reliable than main parachutes, but the real safety advantage comes from the probability of an unlikely main malfunction multiplied by the even less likely probability of a reserve malfunction. This yields an even smaller probability of a double malfunction although the possibility of a main malfunction that cannot be cutaway causing a reserve malfunction is a very real risk.

Parachuting disciplines such as BASE jumping or those that involve equipment such as wing suit flying and sky surfing have a higher risk factor due to the lower mobility of the jumper and the greater risk of entanglement. For this reason these disciplines are generally practiced by experienced jumpers.

Depictions in commercial films – notably Hollywood action movies – usually overstate the dangers of the sport. Often, the characters in such films are shown performing feats that are physically impossible without special effects assistance. In other cases, their practices would cause them to be grounded or shunned at any safety-conscious drop zone or club. USPA member drop zones in the US and Canada are required to have an experienced jumper act as a "safety officer" (in Canada DSO – Drop Zone Safety Officer; in the U.S. S&TA – Safety and Training Advisor) who is responsible for dealing with jumpers who violate rules, regulations, or otherwise act in a fashion deemed unsafe by the appointed individual.

In many countries, either the local regulations or the liability-conscious prudence of the drop zone owners require that parachutists must have attained the age of majority before engaging in the sport.