A hook knife is a pretty basic tool, similar to a letter opener in design. It is usually installed on the container so that the jumper can easily reach it. Some are slipped in behind the mud flap on the main lift web; others are located on the chest strap or down near the leg straps. There are many different brands and styles available, from small, cheap, plastic versions to more expensive, higher-quality models.
From time to time, USPA receives an inquiry from a member asking if it recommends that skydivers carry a hook knife. A look through Section 5-3 of the Skydiver’s Information Manual shows that indeed, USPA does recommend it: “A jumper should always carry a protected but accessible knife.”
Does this mean you should be packing an 18-inch Rambo knife strapped to your leg so you can be ready to start slashing away at a moment’s notice? Not really. In the early days of skydiving, equipment was large and cumbersome, canopies were round and slow, and hook knives were always at the ready—jumpers were always prepared to cut a line or two if the canopy opened with a line-over. Now, our gear is small and sleek, and canopies are flying at warp speeds. Malfunctions are sometimes violent, and the last thing on anyone’s mind during this type of malfunction is, “I think I can fix this with my hook knife!” The truth is that almost no skydiving emergency requires, nor would it benefit from, the use of a hook knife. Therefore, you’re probably better off spending your time and energy working toward another solution. Even so, there are some valid, albeit obscure, reasons to carry one.
Why would you actually need to use a hook knife on a skydive? The answer depends on whom you ask. Some jumpers seem to think they would use a hook knife if the main canopy opened with a line-over malfunction, thus avoiding the need for a cutaway and reserve ride. That’s not really a wise choice in most cases. Who’s to say the main canopy will fly correctly after you cut a line or two? And if you have a line-over, which almost always involves the steering lines, will you be prepared to land your main canopy using just the rear risers once you’ve hacked away the offending line? It would probably be a better idea to cut away the main canopy and deploy your reserve while there is still plenty of altitude remaining for a safe deployment and landing.
You should really use a hook knife as a last resort, such as if a brake or suspension line is over your reserve canopy. However, in-air rigging is never really a good idea, and it just might make your situation worse if you cut the wrong line. In most cases, if you are under your reserve, it means you are at a low altitude, and there will probably not be enough altitude or time to take care of an unusual malfunction that requires the use of a hook knife—especially considering that so many jumpers are descending pretty quickly anyway under canopies with moderate to high wing loadings.
Proper packing and thorough equipment maintenance can help to ensure that your deployments go as planned and there are no messy line entanglements that would require the use of a hook knife. Once you make it past the deployment without a problem, the only other time you might need a hook knife is in the case of a canopy entanglement following a canopy collision. For instance, if another jumper’s main canopy wrapped you up in its fabric and lines following a collision, a hook knife might come in handy to clear yourself from the mess once the jumper released his main. However, bear in mind that with modern canopies, whatever’s going wrong is likely to be happening quickly, and you may not have the time or ability to solve it with a hook knife, particularly if you are close to the ground in your landing pattern, where most collisions occur.
There’s an old skydiving joke that goes like this: Why is it that canopy formation jumpers carry six hook knives? Because they don’t have room to carry more! In reality, canopy formation jumpers usually wear at least two hook knives in case they are caught in a canopy entanglement. Yet CF jumpers rarely use their hook knives in these cases. They always prefer to get out of the entanglement without slashing a bunch of gear if it’s at all possible. Still, it is an option for those who are intentionally flying canopies together in formations, particularly since they usually have more altitude to deal with an entanglement than the average jumper.
Will a hook knife cut through more than a suspension line? Maybe, but the cheaper plastic versions are famous for breaking quite easily. Hook knives are not really effective for cutting harness webbing or tape. The tougher the material, the less likely you are going to hack through it with a hook knife.
If you put your efforts into learning canopy flying skills, creating adequate separation before deployment, flying defensively, clearing your airspace as much as possible and flying a smooth, predictable landing pattern, chances are you will never have to deal with a canopy entanglement. A hook knife should only serve as a last resort, and if it is there, at least you have the option to use it if time allows. But with canopies now so small and fast and most collisions happening below 1,000 feet, the chances of actually being able to use it are pretty slim. But your hook knife doesn’t have to go to waste—if you are still getting bills and letters through the U.S. Mail, they make nice letter openers.
—Jim Crouch | D-16979
USPA Director of Safety & Training