The “BASE” in “BASE jumping”
stands for Buildings, Antennas, Spans (i.e. bridges) and Earth (i.e.
cliffs). Therefore, to do the world’s highest BASE jump off a building,
you need to be leaping off the world’s newest tallest building. So Nasr
Al Niyadi and Omar Al Hegelan lept off the Burj Khalifa, 672 meters (2,204 feet) from the ground. This video shows the jump:
About The BASE Jump
Instead of a ripcord, BASE jumpers release their pilot chute manually.
For higher jumps, the pilot chute is stowed in an easily accessible
pocket or flap, and the jumper pulls it free to release it at the right
moment. This leaves both hands free during the brief freefall. If the
jump is shorter, the jumper usually just holds the pilot chute in his or
her hand.
Angel Falls, Venezuela, a popular BASE jump site.
For jumps 300 feet or lower, BASE jumpers have almost no time at all to
freefall and deploy a chute. They use a static line to deploy the chute
automatically. This line runs from the jumper's pack to the object.
During the jump, this line pulls the main chute open, and then separates
from the pack.
Skydivers
don't have to worry about object proximity. They have to worry about
hitting the ground, not the side of a building or cliff. But most BASE
jumping fatalities are due to object impacts, rather than freefalling to
the ground. The need for fast parachute deployments compounds the
problem -- these deployments can send the jumper off into an unintended
direction, such as straight into a granite wall. Jumpers call this an
"off-heading opening."
Jumpers try to compensate by using a smaller ram-air parachute, one with
seven air cells instead of nine. Modern parachutes designed
specifically for BASE jumping have started to incorporate modified
sliders that ease the suddenness of deployment, making it easier to
avoid an off-heading opening.
Body position at the jump and deployment are key factors in determining
the success of a jump. Jumping head first and rotating forward is
incorrect. Keeping the body oriented so that the jumper is facing down,
with the chute deploying behind him, is vital. On jumps with a few
seconds of freefall, jumpers use tracking to direct the body away from
the object. This means that the jumper "flies" away from the object
using the aerodynamic shape of the body, instead of just falling
straight down.
Canopy skills are vital as well. Once a ram-air parachute has deployed,
the jumper may be carrying a great deal of forward velocity. Being able
to steer properly and avoid slamming into the object could literally be
the difference between life and death.
Source: www.howstuffworks.com
