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Wingsuiting out of a balloon has become a popular way for people to practice their wingsuit BASE exits without the risk of hitting the more commonly jumped cliffs and terrain. Jumping into dead air from a balloon resembles a Base exit and allows for wingsuiters to learn how to start flying their wingsuit in an environment devoid of relative wind.
Although the balloon is a great training tool, it can also create some bad habits. First of all, some have taken to jumping out of a balloon in a wingsuit on their very first balloon jump; this is not the greatest idea. Experiencing dead air for the first time can create instability and at low altitude this danger is compounded by wearing a wingsuit.
The first question I ask someone before considering a wingsuit jump from a balloon is whether they have done a hop 'n' pop in their wingsuit or gone purposely unstable to practice recovering quickly. Both the low altitude awareness and proactive recovery skills learned doing this are necessary before balloon jumping a wingsuit.
There is also a misconception that exiting from a balloon is a good simulation for a jump off a stationary object. What some do not take into consideration is that the balloon basket gives way when you step off of it, which in turn requires a stronger push on exit. When transferring this to wingsuit base, this type of push can result in the loss of altitude if the transition is not done properly.
Jumping head high is another common problem when doing wingsuit balloon jumps and creates bad habits for wingsuit base. Also, it is difficult to determine how fast you begin flying because you do not have any visual references, unless you use a GPS such as a Fly Sight.
For more info see Wingsuit Base Exits article
Ultimately, balloon jumping is a bit more complicated than it seems and shouldn't be used to start training for wingsuit BASE. I recommend that jumpers are proficient in flying the wingsuit they plan to take off the balloon, and that they understand the differences that I have touched on here. It is not a numbers game, it is important to know how to properly fly your wingsuit.