Skydiving is one of the most dynamic and adrenaline-pumping sports around, but jumping out of a plane takes more than just grit – you’ll need a bit of technical knowledge before your leap.

To make sure you are properly prepared for the big drop, brush up on this vital skydiving jargon and get better acquainted with the technical lingo before you plunge through the clouds. When your instructor yells for you to cut away after a box man goes wrong, you’ll want to know what he means.

Here are six essential skydiving terms you need to know.

Altimeter

One of the only flight instruments a light plane actually needs is an altimeter or an altitude meter. This instrument resembles a clock face with a single hand. It indicates your altitude above the ground, in 1,000-foot increments. Audible altimeters beep when you drop beneath a preset height, which are useful if you have a purely visual altimeter and it malfunctions. The latest upgrade in clarity is an electronic flight instrument system with integrated digital altimeter displays. The technology has filtered down from airliners and military planes to become standard in many general aircraft. Altimeter technology is more versatile than you might think. Hikers and mountaineers deploy hand-held or wrist-mounted barometric altimeters. An altimeter is more dependable and often more exact than a GPS receiver for measuring altitude.

Box man

This term refers to the classic skydive or freefall, belly down stance. Box man is a neutral, face-to-earth posture in which the arms form right angles at the shoulder and elbow, and the legs are spread at about 45 degrees from the “long axis” and bent 45 degrees at the knees. The box man is widely seen as the perfect position for formation skydiving. If you hold the perfect, relaxed arch position, you will fall straight down at a constant rate. From this posture you can easily execute turns and forward, backward and sideways movement. To accelerate, you just arch more, letting air slip off easily. Flatten out, or lower your knees and elbows, and you will lose speed, getting more time to admire the view.

Cut away

No skydiving term is more important than cut away. If someone calls for a cut away, they want you to release the main parachute in case of malfunction. Cutting away is a standard emergency procedure performed before deploying the reserve. Also called a breakaway, the technique involves using a simple release system by pulling a handle. In some systems, the cut away or breakaway system will also automatically activate the reserve canopy. In a worst-case scenario, where parts of the faulty main parachute tangle with the skydiver, it may be necessary to use a hook knife to literally cut away from the main parachute. Any time you cut away, the reserve must deploy cleanly and form a good canopy – reasonable buoyancy after making the break. In skydiving, nothing is guaranteed, so you need bags of nerve to take emergency action when dangers arise.

Decision altitude

Decision altitude is terminology that refers to the height at which a skydiver is trained to start execution of emergency measures. Decision altitude is usually 2,500 feet AGL (above ground level) for students, and 1,800 feet for veteran skydivers. The decision altitude may be higher depending upon the nous or comfort of the skydiver. This altitude should be relayed to the jumpmaster and or the pilot before hopping on the aircraft.

Turf Surf

A turf surf is a long, flat skim across the grass with a smooth stop, usually in the wake of a deftly timed and executed high-performance landing. When mistimed, the reverse result is a turf eat: a mouthful of dirt.

Precision landing

Also simply called accuracy, precision landing is a competition discipline in which the skydiver tries to land smack in the middle of an established target. At the elite national level, the target is three centimeters wide – roughly the size of a quarter. Accuracy landings of varying degrees of challenge, from two meters to 20 meters, are required for USPA (United States Parachute Association) licenses. Beginners may struggle just to hit the right field.

Know any other essential skydiving terms that you’ve used on your adventures? Let us know in the comments below or @DegreeMen on Twitter.