Published: September 5, 2017
In skydiving, we use the phrase "ground rush" to succinctly describe the optical illusion that the ground is abruptly rushing up to meet you. The sensation of ground rush is extremely uncommon because of what triggers it: deploying your parachute at an unsafe altitude. It only truly occurs at a way-too-low altitude, when the curvature of the earth comes into peripheral view, giving the sensation of falling.
Ground rush will not affect your tandem skydive, because your parachute will be open before the sensation can take place. If you're more than a little curious about what ground rush is and how it works, no worries! You don't have to experience it for yourself to learn about it. Here's our best shot at explaining the phenomenon.
Step One: Run an Experiment
Ready? Okay. Stand about five long paces from a wall that has visual features on it: paintings or pictures or shelves or knickknacks. Stare at a single doodad and walk towards it at an even pace. At some point on this journey, you're going to notice a dramatic increase in how fast the other items on the wall are visually "spreading out" from the center doodad where you're holding your focus, even though you're not walking any faster. This phenomenon will be most dramatic at the edges of your vision. Some skydivers insist that this is the "ground rush" feeling, defined.
Step Two: Review the Hypotheses
This is purely conjecture, but we have an idea about why this might be so. Humans have built-in motion detectors around the edges of our visual field, intended to alert us to the presence of danger or prey. They exist to divert our attention to the thing in the periphery of our vision that we're pretty sure is going to eat us.
In a sensation of ground rush, those motion detectors are going off all around. (Quick note: Since you don't normally have a 180-degree field of vision, as you would if your eyes were designed to do so, you can't actually see the edges of the true horizon while looking down.) Some skydivers theorize that the eerie feeling that eventuates does so because there's no one direction to look in so as to face off to the danger.
Step Three: Rest Easy
On a tandem skydive, you're going to be under a "there, square and steerable" parachute at about 5,000 feet. That is way above the altitude that skydivers report experiencing ground rush. (Sport skydivers deploy their parachutes at around 3,500 feet; a "super low pull" is somewhere in the 2,500-to-1,800-foot range.) But y'know what? It won't detract anything from your skydive to forego ground rush. It'll only make it better--because you'll know you're in great hands with us!
Want to experience the rush of freefall with a dropzone that's laser-focused on your safety and comfort? Reach out to us and schedule your tandem skydive today!
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» Raymond H.