Parachuting - Parachute Deployment

Parachute Deployment

At a skydiver's deployment altitude, the individual manually deploys a small pilot-chute which acts as a drogue, catching air and pulling out the main parachute or the main canopy. There are two principal systems in use : the "throw-out", where the skydiver pulls a toggle attached to the top of the pilot-chute stowed in a small pocket outside the main container : and the "pull-out", where the skydiver pulls a small pad attached to the pilot-chute which is stowed inside the container.

Throw-out pilot-chute pouches are usually positioned at the bottom of the container – the B.O.C. deployment system – but older harnesses often have leg-mounted pouches. The latter are safe for flat-flying, but often unsuitable for freestyle or head-down flying.

In a typical non-military parachute system, such as the throw-out, the pilot-chute is connected to a line known as the "bridle", which is in turn attached to a small deployment bag that contains the folded parachute, with the suspension lines stowed in rubber bands. At the bottom of the container that holds the deployment bag is a closing loop which, during packing, is fed through the grommets of the four flaps that are used to close the container. At that point, a curved pin that is attached to the bridle is inserted through the closing loop. The next step involves folding the pilot-chute and placing it in a pouch (e.g. B.O.C pouch).

Activation begins when the pilot chute is thrown out. It inflates and creates drag, pulling the pin out of the closing loop and allowing the pilot-chute to pull the deployment bag from the container. The parachute lines are pulled loose from the rubber bands and extend as the canopy starts to open. A rectangular piece of fabric called the "slider" (which separates the parachute lines into four main groups fed through grommets in the four respective corners of the slider) slows the opening of the parachute and works its way down until the canopy is fully open and the slider is just above the head of the skydiver. The slider slows and controls the deployment of the parachute. Without a slider, the parachute would inflate fast, potentially damaging the parachute fabric and/or suspension lines. During a normal deployment, a skydiver will generally experience a few seconds of intense deceleration, in the realm of 3 to 4 G, while the parachute slows the descent from 120 mph (190 km/h) to approximately 18 mph.

If a skydiver experiences a malfunction of their main parachute which they cannot correct, they pull a "cut-away" handle on the front right-hand side of their harness (on the chest) which will release the main canopy from the harness/container. Once free from the malfunctioning main canopy, the reserve canopy can be activated manually by pulling a second handle on the front left harness. Some containers are fitted with a connecting line from the main to reserve parachutes – known as a reserve static line (RSL) – which pulls opens the reserve container faster than a manual release could. Whichever method is used, a spring-loaded pilotchute then extracts the reserve parachute from the upper half of the container.