BASE Jumping Equipment & Techniques Leeds

BASE jumping grew out of skydiving (recreational parachuting from aircraft). There are three main technical differences between the two.

1. BASE jumps are generally made from much lower altitudes than skydives.
2. A BASE jump takes place in close proximity to the cliff or tower which provided the jump platform.
3. The BASE jumper generally has a lower airspeed than a skydiver throughout the jump, because a BASE jump starts with zero airspeed, and (due to the limited altitude) a BASE jumper very seldom approaches the terminal velocity (airspeed) of a skydiver.

All three factors have significant implications.

Firstly, the BASE parachute system has to be made to open very quickly at low airspeeds. Skydiving parachutes are reefed to slow down the opening and reduce opening shock forces. Secondly, the cliff or tower presents a risk to the BASE jumper if, for example, the parachute opens facing backwards. An off-heading opening is not considered a problem in skydiving, but has caused fatal impact injuries in BASE jumping. Off heading opening resulting in object strike is the leading cause of serious injury and death in BASE jumping.

An experienced skydiver is recommended to deploy their parachute no lower than 2,000 feet (610 m). At that time, if they have already been in freefall for at least 1,000 feet (305 m), the jumper is traveling 120 miles per hour (54 m/s), and is 11 seconds from the ground. Most BASE jumps are made from less than 1,000 feet (305 m). For example, a BASE jump from a 500 foot (152 m) object is about 6 seconds from the ground if the jumper remains in freefall. On such a jump, the parachute must open at about half the airspeed of the skydiver, and more quickly (that is, in a shorter distance fallen). Standard skydiving parachute systems are not designed for this situation.

Many BASE jumpers use specially designed harnesses and parachute containers, with extra large pilot chutes, and jump with only one parachute - since, with a total freefall time of 6 seconds, there would be no time to use a reserve parachute. In these systems, the actual parachute canopy should also be specifically manufactured for BASE jumping, however skydiving parachutes with some modifications (primarily the addition of a tail pocket for stowing suspension lines) are occasionally used by those unable to purchase appropriate equipment.

The rest of the system is almost always specifically designed for BASE use. Standard skydiving equipment can only be used on relatively high BASE jumps. If modified, by removing the bag and slider, stowing the lines in a tail pocket, and fitting a large pilot chute, standard skydiving gear can be used for lower BASE jumps, but is then prone to kinds of malfunction which are rare in normal skydiving (such as "line-overs" and broken lines).

The vast majority of people who try BASE jumping are those that have already learned to skydive. It is important to know how to safely ...