Sky diving

Parachuting, also known as skydiving, is the sport of jumping from enough height to deploy a fabric parachute and land safely.

The history of parachuting appears to start with Andre-Jacques Garnerin who made successful parachute jumps from a hot-air balloon in 1797. The military developed parachuting technology first as a way to save aircrews from emergencies aboard balloons and aircraft in flight, later as a way of delivering soldiers to the battlefield. Early competitions date back to the 1930s, and it became an international sport in 1951.

Sport Parachuting is performed as a recreational activity and a competitive sport, as well as for the deployment of military personnel Airborne forces and occasionally forest firefighters.

In the early days, a trained skydiver (or jumper) and a group of associates met at an isolated airport, sometimes referred to as a "drop zone." (DZ) A fixed base operator at that airport usually operates one or more aircraft, and takes groups of skydivers up for a fee. It was common for an individual jumper to go up in a Cessna light aircraft such as C-172 or C-182. These days, it is common for busier DZs near populated areas to use multiple, larger aircraft such as the Cessna Caravan C208, De Havilland Twin Otter DHC6 or Short Skyvan.

A typical jump involves individuals jumping out of an aircraft (usually an airplane, but sometimes a helicopter or even the gondola of a balloon), at approximately 4,000 meters (around 13,000 feet) altitude, and free-falling for a period of time before activating a parachute to slow the landing down to safe speeds.

Once the parachute is opened, (usually the parachute will be fully inflated by 2,500 ft). the jumper can control his or her direction and speed with toggles on the end of steering lines attached to the trailing edge of the parachute, and so he or she can aim for the landing site and come to a relatively gentle stop in a safe landing environment. All modern sport parachutes are self-inflating "ram-air" wings that provide control of speed and direction similar to the related paragliders. Purists in either sport would note that paragliders have much greater lift and range, but that parachutes are designed to absorb the stresses of deployment at terminal velocity.

By manipulating the shape of the body—as a pilot manipulates the shape of his aircraft's wings—a skydiver can generate turns, forward motion, backwards motion, and even lift. Experienced skydivers say that in freefall one can do anything a bird can do, except go back up.

When leaving an aircraft, for a few seconds a skydiver continues to travel forwards as well as down, due to the momentum created by the plane's speed (known as throw-forward). The perception of a change from horizontal to vertical flight is known as the "relative wind", or informally as "being on the hill". In freefall, skydivers generally do not experience a "falling" sensation because the resistance of the air to their body at speeds above about 50 mph (80 km/h) provides some feeling of weight and direction. At normal exit speeds for aircraft (approx 90 mph (140 km/h)) there is little feeling of falling just after exit, but jumping from a balloon or helicopter can create this sensation. Skydivers reach terminal velocity (around 120 mph (190 km/h) for belly to Earth orientations, 150-200 mph (240-320 km/h) for head down orientations) and are no longer accelerating towards the ground. At this point the sensation is as of a hard wind.Many skydivers make their first jump with an experienced and trained instructor (this type of skydive may be in the form of a tandem skydive). During the tandem jump the jumpmaster is responsible for the stable exit, maintaining a proper stable freefall position, and activating and controlling the parachute. With training and experience, the fear of the first few jumps is supplanted by the tact of controlling fear so that one may come to experience the satisfaction of mastering aerial skills and performing increasingly complicated maneuvers in the sky with friends.
Skills
Parachuting has complex skills that can take thousands of jumps to master, but the basics are often fully understood and useful during the first few jumps. There are four basic areas of skill: basic safety, free fall maneuvers, parachute operation, and landing.

Free-fall maneuvers

In freefall most skydivers start by learning to maintain a stable belly to earth "arch" position.In this position the average fall rate is around 190 km/h (120 mph). Learning a stable arch position is a basic skill essential for a reliable parachute deployment. Next, jumpers learn to move or turn in any direction while remaining belly to earth. Using these skills a group of jumpers can create sequences of formations on a single jump, a discipline formerly known as relative work (RW) and now as formation skydiving (FS). In the late 1980s more experienced jumpers started experimenting with freeflying, falling in any orientation other than belly to earth. Today many jumpers start freeflying soon after they earn their license, bypassing the traditional flat-flying stepping stone.

Parachute operation and landing :
The decision of when to deploy the parachute is a matter of safety. A parachute should be deployed sufficiently high to give the parachutist time to handle a malfunction, should one occur. 600 metres (1,970 ft) is the practical minimum for advanced skydivers.Skydivers monitor their altimeters during freefall to decide when to break off from the formation (if applicable) and when to open their parachutes. Many skydivers open higher to practice their parachute flying skills. During a "hop-and-pop," a jump in which the parachute is deployed immediately upon exiting the aircraft, it is not uncommon to be under canopy as high as 1200 to 1500 meters (4000 to 5000 ft).Parachute flying involves two basic challenges. Firstly to avoid injury and secondly to land where planned, often on a designated target. Some experienced skydivers enjoy performing aerobatic maneuvers with parachutes, the most notable being the "Swoop". This is a thrilling, but dangerous maneuver entailing a steep, high speed landing approach, before leveling off a couple of feet above the ground to maintain a fast glide parallel to the surface. Swoops as far as 180 metres (590 ft) have been achieved.

A modern parachute or canopy "wing" can glide substantial distances. Elliptical canopies go faster and farther, and some small, highly loaded canopies glide faster than it is possible to run, which can make them very challenging to land. A highly experienced skydiver using a very small canopy can achieve over 100 km/h (60 mph) horizontal speeds in landing.

Today, the majority of skydiving related injuries and deaths happen under a fully opened and functioning parachute. The most common cause being poorly-executed, radical maneuvers near to the ground, such as hook turns, or landing flares performed either too high or too low.

Safety:
Despite the perception of danger, fatalities are rare. However, each year a number of people are hurt or killed parachuting world-wide.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.[citation needed] In recent years, 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 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.

Equipment failure rarely causes fatalities and injuries. Exact numbers are difficult to estimate but approximately one in a thousand deployments of a main parachute results in a malfunction. Ram-air parachutes typically spin uncontrollably when malfunctioned, and must be jettisoned before deploying the reserve parachute. Reserve parachutes are packed and deployed differently, they are also designed more conservatively and built & 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.

Types:
There are several different disciplines to embrace within parachuting. Each of these is enjoyed by both the recreational (weekend) and the competitive participants.
Types of parachuting include:
* Accuracy landing - Landing as close as possible to a target.
* BASE jumping - From buildings, antennas, bridges (spans) and cliffs (earth).
* Blade running - A kind of slalom with a parachute.
* Big-ways - Formation skydiving with many people all falling belly to earth.
* Canopy formation - Making formations with other parachutists while under canopies. (Known also as canopy relative work or simply CRW (CRew))
* Canopy piloting - Also known as 'swooping'.
* Formation skydiving - Making formations during freefall. (Known also as relative work or simply deployment-position RW)
* Freefall style
* Freeflying - Flying in multiple orientations (i.e. head down, flocking, and sitflying). A more advanced approach to skydiving.
* Freestyle skydiving
* Military Parachuting
o HALO/HAHO
o Treejumping
* Para-ski
* Speed Skydiving - represents the fastest non-motorized sport on Earth, with Speed in excess of 500 km/h (310 mph)
* Skysurfing - Skydiving with a board strapped to one's feet.
* Vertical Formation Skydiving - a subset of Formation skydiving that uses high-speed freeflying body positions instead of bellyflying. (Known also as VRW)
* Wingsuit flying - Skydiving with a suit which provides extra lift, and powered skydiving where the wingsuit flyer adds propulsion.

resource :wikipedia