BASE jumping () is the activity of jumping from fixed objects, using a parachute to descend to the ground. BASE is an acronym that stands for four categories of fixed objects from which one can jump: buildings, antennas (referring to radio masts), spans (bridges) and earth (cliffs). Participants jump from a fixed object such as a cliff and, after an optional freefall delay, deploy a parachute to slow their descent and land. A popular form of BASE jumping is wingsuit BASE jumping.
In contrast to other forms of parachuting, such as skydiving from airplanes, BASE jumps are performed from fixed objects that are generally at much lower altitudes, and BASE jumpers only carry one parachute.
BASE jumping is significantly more hazardous than other forms of parachuting and is widely considered to be one of the most dangerous extreme sports.
Fausto Veranzio is widely believed to have been the first person to build and test a parachute, by jumping from St Mark's Campanile in Venice in 1617 when he was more than 65 years old. However these and other sporadic incidents were one-time experiments, not a systematic pursuit of a new form of parachuting.
Precursors to the activity date back hundreds of years. In 1966 Michael Pelkey and Brian Schubert jumped from El Capitan in Yosemite National Park. The acronym B.A.S.E. (now more commonly BASE) was later coined by filmmaker Carl Boenish, his wife Jean Boenish, Phil Smith, and Phil Mayfield. Carl Boenish was an important catalyst behind modern BASE jumping and in 1978 he filmed jumps from El Capitan made using ram-air parachutes and the freefall tracking technique. While BASE jumps had been made prior to that time, the El Capitan activity was the effective birth of what is now called BASE jumping.
After 1978 the filmed jumps from El Capitan were repeated, not as an actual publicity exercise or as a movie stunt but as a true recreational activity. It was this that popularized BASE jumping more widely among parachutists. Carl Boenish continued to publish films and informational magazines on BASE jumping until his death in 1984 after a BASE jump off the Troll Wall. By this time the concept had spread among skydivers worldwide, with hundreds of participants making fixed-object jumps.
During the early eighties, nearly all BASE jumps were made using standard skydiving equipment, including two parachutes (main and reserve), and deployment components. Later on, specialized equipment and techniques were developed specifically for the unique needs of BASE jumping.
In recent years, recognizing the activity's growing appeal and the potential for high-impact marketing, companies such as Red Bull have stepped in to sponsor athletes, further elevating the activity's profile.
Upon completing a jump from all of the four object categories, a jumper may choose to apply for a "BASE number", awarded sequentially by Rick and Joy Harrison.
In the early days of BASE jumping, people used modified skydiving gear, such as by removing the deployment bag and slider, stowing the lines in a tail pocket, and fitting a large pilot chute. However, modified skydiving gear is prone to kinds of malfunction that are rare in normal skydiving (such as "line-overs" and broken lines). Modern purpose-built BASE jumping equipment is considered to be much safer and more reliable.
The biggest difference in gear is that skydivers jump with both a main and a reserve parachute, while BASE jumpers carry only one parachute. BASE jumping parachutes are larger than skydiving parachutes and are typically flown with a wing loading of around 3.4 kg/m2 (0.7 lb/sq ft). Vents are one element that make a parachute suitable for BASE jumping. BASE jumpers often use extra large pilot chutes to compensate for lower airspeed parachute deployments. On jumps from lower altitudes, the slider is removed for faster parachute opening.
BASE jumpers use a single-parachute harness and container system. Since there is only a single parachute, BASE jumping containers are mechanically much simpler than skydiving containers. This simplicity contributes to the safety and reliability of BASE jumping gear by eliminating many malfunctions that can occur with more complicated skydiving equipment. Since there is no reserve parachute, there is little need to cut-away their parachute, and many BASE harnesses do not contain a 3-ring release system. A modern ultralight BASE system including parachute, container, and harness can weigh as little as 3.9 kilograms (8.6 lb).
When jumping from high mountains, BASE jumpers will often use special clothing to improve control and flight characteristics in the air. Wingsuit flying has become a popular form of BASE jumping in recent years, allowing jumpers to glide over long horizontal distances. Tracking suits inflate like wingsuits to give additional lift to jumpers, but maintain separation of arms and legs to allow for greater mobility and safety.
BASE jumps can be broadly classified into low jumps and high jumps. The primary distinguishing characteristic of low BASE jumps versus high BASE jumps is the use of a slider reefing device to control the opening speed of the parachute, and whether the jumper falls long enough to reach terminal velocity.
Low BASE jumps are those where the jumper does not reach terminal velocity. Sometimes referred to as "slider down" jumps because they are typically performed without a slider reefing device on the parachute. The lack of a slider enables the parachute to open more quickly. Other techniques for low BASE jumps include the use of a static line, direct bag, or P.C.A. (pilot chute assist). These devices form an attachment between the parachute and the jump platform, which stretches out the parachute and suspension lines as the jumper falls, before separating and allowing the parachute to inflate. This enables the very lowest jumps—below 60 metres (200 ft) to be made. BASE jumpers have been known to jump from objects as low as 30 metres (100 ft), which leaves little to no canopy time and requires an immediate flare to land safely.
Many BASE jumpers are motivated to make jumps from higher objects involving free fall. High BASE jumps are those which are high enough for the jumper to reach terminal velocity. High BASE jumps are often called "slider up" jumps due to the use of a slider reefing device.
High BASE jumps present different hazards than low BASE jumps. With greater height and airspeed, jumpers can fly away from the cliff during freefall, allowing them to deploy their parachute far away from the cliff they jumped from and significantly reduce the chance of object striking. However, high BASE jumps also present new hazards such as complications resulting from the use of a wingsuit.
Tandem BASE jumping is when a skilled pilot jumps with a passenger attached to their front. It is similar to skydiving and is offered in the US and many other countries. Tandem BASE is becoming a more accessible and legal form of BASE jumping.