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Choices About Containers

Posted Wednesday, December 21, 1994

By Bryan Burke

When its time to buy your first container, there will be as many choices to make as there are when you buy your canopies. Virtually any container in production in the US today is reasonably safe. Just be sure it is in good condition and appropriately sized for your body and the parachutes you plan to put in it. Some terms will come up in any discussion about containers, and the purpose of this section is to explain how some systems work and their advantages and disadvantages.

Main Deployment Method

There are several ways a main parachute can be deployed. Which system you choose is most likely to be determined by what the experienced skydivers on your dz jump. This choice seems to be as much dz fashion as anything else. However, over the last few years, the Bottom of Container Pilot Chute has gained in popularity. At the 1993 World Championships, probably 75% of the competitors chose this method.

Ripcord

There is a reason why every reserve container on the market today employs ripcord deployment for the reserve. Ripcord deployment keeps everything inside the container; there is no bridle or pilot chute outside, eliminating the possibility of misrouting these or having them snagged. Ripcord handles are hard to snag, and even if they are dislodged, they must be pulled before deployment starts. Another big advantage is they can be pulled with either hand, a feature not normally needed but which could make a vital difference in an emergency where one hand or arm is disabled. Finally, they are at least as likely to work in an unstable deployment as any other method.

Why do so few experienced jumpers use a ripcord? Most will tell you that ripcords have certain inconveniences. They can be slightly harder to pack, but anyone with experience packing them will tell you this is hardly a problem. You do have to keep the ripcord, which is slightly inconvenient. And no one has devised a collapsible spring loaded pilot chute. If you want a collapsible pilot chute (see further below to learn about these) you can't have a ripcord.

The true reason experienced jumpers don't use ripcords is really an image thing. Ripcords have a "student" look to them, just like helmets. The fact that they are safe and practical doesn't make them cool. Ripcords went out of the mainstream in the late 70s. At that period in skydiving, Relative Workers wore huge jumpsuits with lots of fabric and wings. The burble behind these suits was so large that a conventional ripcord/spring pilot chute often produced a pilot chute in tow. The solution was to deploy the pilot chute to the side, into clear air. Since this was a hot item, everyone wanted one. Jumpsuits eventually shrank back to a reasonable size, but the hand deploy pilot chute remained.

Hand Deployment

There are two types of hand deploy pilot chutes. One is the "throw out," which means the pilot chute is located on a pouch outside of the container. When deployment time comes, you just grab the pilot chute handle and toss it to the side. "Pull out" pilot chutes are actually packed inside the container. To deploy them, you grab a handle and pull a lanyard that goes to the pin holding the container closed. The pilot chute is also attached to the lanyard. The action of pulling the handle out to the side first opens the container and then pulls the pilot chute out to the side.

Pull Out versus Throw Out

Skydivers who use throw outs tend to disparage pull outs, and vice versa. Generally argument centers around a simple dispute, and that is what sort of total malfunction you would prefer to have if the system (or operator) doesn't work. With a pull out, the container is still closed if the handle is dislodged. Nothing comes out unless the handle is pulled. Pull out partisans argue that you don't need to worry about being inadvertently deployed if your handle is knocked loose. With a throw out, if the handle is dislodged, the pilot chute is out and deployment begins. People preferring pull outs also say that you are unlikely to have a pilot chute in tow situation, because you, not the pilot chute, extract the pin. Finally, unlike a belly band or leg mounted pilot chute, you can't misroute the bridle and there is no bridle outside of the container to snag on things or blow loose in the wind.

Friends of the throw out don't like pull outs because if your pull out handle is dislodged, you may have trouble grabbing the lanyard blowing around on your back. A remarkable number of reserve rides, and quite a few fatalities, have resulted from this situation. If your handle is dislodged on a throw out, deployment is initiated. This is potentially dangerous of course, but usually just results in the dive being redesigned after the victim is extracted at an unplanned altitude. Statistically you are less likely to face a reserve ride, injury, or death from a premature deployment than you are from a lost pull out handle. Another problem with pull outs is that since the pilot chute is only pulled out as far as your hand, as opposed to being thrown several feet to the side, a negligent pull can leave you with your pilot chute on your back.

These days an increasing number of skydivers are using a throw out positioned on the bottom of the container, where pull out handles are located. This offers the secure and easy to reach position of a pull out and eliminates exposed bridle. Yet it retains the advantages of a throw out. This option seems to offer the fewest disadvantages and is as simple and safe as any system except possibly ripcord deployment.

Collapsible pilot chutes

A collapsible pilot chute is one that deflates after the parachute opens. This means the pilot chute has less drag, giving the main parachute a slight increase in speed and therefore in performance. On the down side, it is one more thing to go wrong. If a collapsible pilot chute is improperly designed, built, maintained, or packed, it may not work at all. If you decide to get one, make sure you are thoroughly acquainted with its operation.

Reserve Static Lines (RSLs)

Almost every main container made now comes with the option of a Reserve Static Line, commonly referred to as an RSL. They may also be called Stevens systems, after Perry Stevens, who came up with the concept over twenty years ago. Rigs without RSLs can easily have them added by a competent rigger.

The RSL is very simple. It consists of a lanyard linking the main canopy riser(s) to the reserve ripcord cable. If the main is cut away, the RSL pulls the reserve ripcord, deploying the reserve. (It should be obvious that the RSL only works with a main canopy out - in the event of a total it may as well not be there.) Since a significant number of fatalities involve jumpers who cut away but do not pull their reserve or pull to late, an RSL is a good idea in many ways. In fact, there are only two situations where an RSL can be a problem.

One is in a violent malfunction, where an immediate reserve deployment is equivalent to an unstable deployment. However, a great many skydivers are not aware enough of their altitude to justify taking a delay between cutaway and reserve deployment. Malfunctions can be extremely disorienting, and can also have a high descent rate. The average jumper is probably better off getting the emergency procedures done immediately, and an RSL can shave a second or two off the time between cutaway and reserve pull.

Another situation where an RSL can be a hazard is in a canopy wrap. In the case of CRW, a person should disconnect the RSL before the jump. But what about unintentional wraps following RW? This is a case where the RSL could be a problem, since the correct procedure (altitude permitting) is to disconnect the RSL, cut away to get clear of the canopy entanglement and then pull the reserve. Most people who have been in wraps would agree that reaching the RSL disconnect would be difficult in this type of situation. However, canopy wraps cause fewer fatalities than low/no pulls and are easily avoided by good separation and canopy procedures. Statistically you are better off with an RSL in this case too. Skydive Arizona's Safety and Training Advisor strongly recommends an RSL for anyone who is not extremely current and experienced. You should definitely get one on your first rig.

Single Operation Systems (SOSs)

One method of simplifying emergency procedures is the Single Operation System. These are commonly used on student rigs, including the ones here. An SOS incorporates the functions of cut away handle and reserve handle in one. That means that faced with an emergency the operator need remember only one procedure: pull the handle. There are only three reasons this system is not in common use among experienced jumpers. Two were covered above, in the section on RSLs: you can't delay reserve deployment if you are unstable or in a wrap. The third is that you cannot cut away the main in winds to escape from being dragged. With an RSL, you have the advantages of an SOS but the added options of releasing the RSL for canopy relative work or high wind situations.

Automatic Activation Devices (AADs)

An increasing number of skydivers are choosing to put an Automatic Activation Device, or AAD, on their reserve. These devices have improved greatly over the years, to the point where there are few if any reasons not to have one - provided it is modern and correctly installed and maintained. Accident studies indicate that 50% or more of skydiving fatalities might not have happened if the people involved had AADs.

AADs all work on a simple principle. As you fall through the air, they sense your descent rate just as an altimeter does. When you pass through their arming altitude - somewhat higher than their firing altitude - they begin to calculate your descent rate. At the preset firing altitude they attempt to open your reserve if you are exceeding a certain speed. Two common types do this by pulling the reserve ripcord, while another version cuts the reserve closing loops. The two older designs commonly seen, the Sentinel and the FXC, have certain limitations a user should be aware of. The more recent CYPRES design is very easy to use and has earned an excellent reputation. Be sure to read the owner's manual thoroughly before you use an AAD of any type.

Bryan BurkeSkydive Arizona


Source
Newsgroups: rec.skydiving
Subject: Choices About Containers
Date: 21 Dec 1994 17:39:48 -0500
Reply-To: skyaz@aol.com (SkyAZ)





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