Sky diving
Sky diving is a recreational activity. A trained sky diver (or jumper) and a group of associates meet at an isolated airport. A fixed-base operator at that airport usually operates one or more light cargo aircraft, and takes groups of skydivers up for a fee.The sport is extremely exciting at first, and has complex skills that can take thousands of jumps to master. There are four basic areas of skill: basic safety, free fall maneuvers, parachute operation, and landing.
Basic safety includes knowledge of parachute operation, including how to pack a parachute, when to open one's parachute, and how to land safely. Most national sport organizations certify instructors, most operators who fly skydivers retain an instructor, and all certified instructors can teach the basics well enough for a student to be licensed by the national sport organization.
Most sky-divers say that they feel that they are flying in free fall. Experienced sky-divers can change their downward rate from a low of 120 mph, to more than 200mph. They have complete control over their body position, and can approach other skydivers without danger of injury to either party.
Inexperienced skydivers are a substantial hazard in the air. For the first few jumps, most beginners are required to jump in a linked harness, with an instructor in the other harness. Even newly-licensed skydivers are shunned by groups until they've completed fifty to a hundred jumps, and their experience is personally known to a number of people on the field. For many sky-divers this is not nastiness, or elitism, but a simple desire not to have anything broken.
Choosing when to open the parachute is a matter of safety. If opened too low, a parachute may not deploy in time to break the skydiver's fall. A thousand feet (~300m) is the practical minimum, and to go this low, skydivers must use their altimeter. Many skydivers open higher to practice flying their parachute.
Flying the parachute has two basic challenges: 1. To land where you planned, often on a target. 2. To avoid injury. On a more advanced note, some skydivers enjoy performing aerobatic maneuvers with parachutes.
Modern parachutes are wings, and can glide substantial distances. Elliptical parachutes go faster and farther, and some small, highly loaded ellipticals glide faster than a man can run, which can make them very challenging to land.
A good landing will not have any discomfort at all, and will land the skydiver within a few feet of his intended location. Champion skydivers routinely land less than 1/3 meter from the center of a target. Neophytes do well to hit the landing field and avoid a sprain.
With a parachute, the ground is dangerous. Common wisdom is to avoid speed. high swings and other high-energy maneuvers near the ground. The most common reason for injury in the sport is a badly-executed low maneuver with a fast, open parachute.
After landing comes the most hazardous operation of all. The skydiver has to repack his parachute. It's always a temptation to put it off, or to hurry to make the next plane, and this is how accidents happen and 'chutes get damaged.
In the U.S., skydiving is regulated by a combination of voluntary industry standards and government safety standards. Most operators refuse to take sky divers who are not licensed by a national sport organization. FAA regulations require civilian sport parachute rigs to have a professionally-packed "reserve 'chute." Professional parachute riggers are licensed by the FAA.
The basic safety statistics are roughly this: The main parachute will fail to open roughly one in a hundred jumps- less often if it is new, and the skydiver packs it carefully. A reserve will fail roughly one in three hundred to five hundred jumps. Thus, the average sky-diver has a roughly one in twenty thousand chance of dying on any given jump. At ten jumps per week-end, most sky-divers would have to jump 400 years before their luck would be likely to run out.
See also parachute, recreation