Posted Tue Jul 11 2006

By Scott Miller

Photo 1 Photo 2 Photo 3 Photo 4 Photo 5 Photos of Jeff Gladish Photos: Marat Leiras

Many factors determine the way your canopy opens. The design of the canopy and the way it is packed are two important factors, but body position also plays a major role.

We learn to deploy our canopies in a basic, stable position as students, and many of us don’t give this skill much more thought after that. Unfortunately, we sometimes develop a few bad habits that have a negative effect on our openings.

Even after making thousands of jumps, people have been surprised to find that a few small adjustments to their body position during deployment can significantly improve their openings.

This article is about deploying a parachute, one of the most important things you do on every skydive. It might be a good idea to practice these techniques on the ground before trying them in the air. You might even want to make a solo jump and try some practice pulls using these techniques before it’s actually time to deploy.

If you are not a licensed skydiver yet, or have just recently earned your license, you should discuss this article with your instructor before trying anything you read here. He or she may want you to focus on more important skills, like altitude awareness and basic stability, rather than adding anything new to your pull sequence.

No Need for Speed

The speed at which you are falling when you deploy your canopy can have a large effect on the forces generated during the opening. As your airspeed increases, these forces also increase.

Many of today’s canopies are designed for relatively slow openings, and some will not be affected greatly by a little extra speed at deployment time. Some jumpers even find that their canopies open better when they are falling a bit faster. This is not something you should take for granted, though.

Higher airspeeds might not cause a canopy to open hard as long as everything else is just right, but small variables tend to have greater effects at higher airspeeds. If you rush your pack job one time and let things get a little sloppy, or if your canopy is starting to go out of trim, extra airspeed could make the difference between an opening that is slightly abrupt and one that really hurts.

Slowing down before you deploy can provide a greater “margin of error” and reduce the effects that other variables have on your openings. Slowing down can be especially helpful if your openings are frequently or even just occasionally faster than you like them to be.

Vertical or “freefly” body positions like head-down or sit-flying allow you to reach much higher airspeeds than “flat” body positions. This extra speed makes flattening out and slowing down before you pull particularly important. Both beginners and experienced freeflyers should keep this in mind when planning their dives. Even if you don’t freefly, simply tracking at the end of a belly-to-earth jump can significantly increase your airspeed, and you may still find it helpful to “flare out” of the track and slow down before you deploy.

To flare out of a track, spread your arms and legs and de-arch slightly for a second as shown in Photo 1. This will help bleed off any excess speed. Keep your arms and legs spread out and maintain a slight de-arch while you wave off, remembering to look around for other jumpers. As you finish your wave-off and start to pull, relax back into a normal arch. If done correctly this doesn’t take a significant amount of time and becomes a natural part of your wave off.

What Are You Looking At?

Take a moment to notice where you are looking while you reach for your pilot chute. If you jump with a video camera, look at some of your openings on tape. What do you see in the video as you pull? Are you looking up at the horizon, or down at the ground below you? Do you look back toward your pilot chute handle as you reach for it? Do you look over your shoulder after you pull?

Older skydiving rigs used spring-loaded main pilot chutes activated by a ripcord. Even in the late 1990′s this type of system was still used on most student rigs. Those of us who were trained using this type of system were taught to look for the ripcord handle before grabbing it. We were also taught to look over one shoulder and “check” after pulling the ripcord. Looking over your shoulder changes the airflow over your back and helps clear pilot chute hesitations, which are common when using a spring-loaded main pilot chute.

Most licensed jumpers use hand-deployed main pilot chutes, and these are becoming the standard for student training as well. Even if years have passed since they transitioned to a hand-deployed pilot chute, many experienced jumpers still have the habit of looking for their pilot chutes as they reach for them and checking over one shoulder after they throw them. Unfortunately, it’s almost impossible to look over your shoulder and keep your shoulders level at the same time. Looking over your shoulder also tilts your container to one side (Photo 2).

Although large, docile student canopies may not get offended if your shoulders and container are uneven, more responsive sport canopies will be much happier if you keep your shoulders level. Having your shoulders and container tilted as the canopy deploys can cause off-heading openings, line twists, and can even cause a hard opening.

Most of us have our pilot chutes mounted on the bottom of the container, so trying to look for the handle is really useless. Even if you still use a legstrap-mounted pilot chute, you probably can’t see the handle very easily in freefall. Since hand-deployed pilot chutes are thrown into the clean air next to your body, pilot chute hesitations rarely occur and checking over your shoulder every time isn’t necessary.

Some people have a habit of looking straight down as they deploy. This tends to put you in a slightly head-low attitude, which can increase your airspeed slightly. It can also amplify the opening force your body feels, since this force will mainly be transmitted to your shoulders when the canopy reaches the end of the lines. Also, your legs may swing through a wider arc as the canopy sits you up in the harness, making the opening feel more abrupt.

Instead of looking for your handle or looking down at the ground, try lifting your head up and looking out at the horizon as you reach for your main deployment handle (Photo 3). This puts you in a more head-high attitude. The opening forces will be transmitted farther down through the harness instead of being concentrated at your shoulders.Looking at the horizon also helps keep your shoulders and container level as you pull.

After throwing the pilot chute, bring your arms back into a neutral freefall position and think about keeping your shoulders level as the deployment bag lifts off of your back (Photo 4). You can also push your hips down slightly and bend your knees just a bit, as if you were in a very slow backslide. This keeps your head and upper body high. In the past, some jumpers have recommended “sitting up” during the deployment. This can actually work well as long as it is done correctly, but if you sit up too much or too soon there is a risk of increasing your airspeed or even becoming unstable. Simply lifting your chin, looking at the horizon, arching a bit more, and relaxing your legs slightly has a similar effect to consciously sitting up, and you’re less likely to overdo it.

Some people who jump with side-mounted cameras believe it’s necessary to keep their heads down when they deploy, to prevent a riser from hitting the camera. This might be an issue if you have narrow shoulders or wear your chest strap very tight, leaving less room between your risers. It also might be a problem if your camera sticks out from the side of your helmet quite a bit. It’s best to minimize this problem by keeping side-mounted cameras as small, streamlined, and snag-free as possible. If you’re convinced it’s necessary to keep your chin down, at least keep a good arch and relax your lower legs to keep your shoulders higher than your hips, and also focus on keeping your arms and shoulders level in the relative wind.

Back in the Saddle

As soon as the canopy sits you upright in the harness, try putting your feet and knees together for the rest of the opening (Photo 5). Putting your legs together helps keep your weight even in the harness and reduces the chances of an off-heading opening. This is especially effective if you are jumping an elliptical-type canopy. Just the weight of your legs swinging around or a small weight shift in the harness can cause some of these canopies to start turning.

If you grab your risers as the canopy is opening it’s best to hold the lower part of the risers, just above the 3-Ring system. If you grab the risers up near the toggles you might make the canopy turn by unintentionally pulling one riser or releasing one brake. If you hold on to the bottom of the risers, you can still slide your hands up quickly to steer with the risers or release the brakes if necessary.

Some jumpers try to keep their openings on heading by actively steering with their rear risers while the slider is still up against the canopy. This works with some canopies, but other canopies don’t like it at all. You may get better results if you just relax, sit still, focus on keeping your weight even, and wait until the slider starts to come down before making any corrections with the risers.

Watch Where You’re Going

In a first jump course we are taught to check our canopies to make sure they open correctly. Although this is important, it can also create a very bad habit. Many jumpers look up at their canopies as soon as they start to open, and continue watching the canopy through the entire opening sequence. Some people continue looking up for several more seconds while they collapse their sliders and release their brakes.

If another person opens close to you, you may only have a second or two to react in order to avoid a collision. Staring up at your canopy for five or ten seconds after you deploy is like driving down the highway while staring up at the roof of your car.

Fortunately, a few techniques can help you avoid this problem.

Many students are taught to count out loud while their canopy deploys, saying “arch, reach, pull, one thousand, two thousand, three thousand…” If you don’t do this already it’s a good habit to create, and can help you keep track of time during the deployment sequence.

You will hear and feel different things during each stage of the deployment. A second or less after you throw your pilot chute, you should feel the snatch force pull you upright in the harness. This is the force of the canopy fabric hitting the relative wind as it comes out of the deployment bag.

The canopy will then snivel. The snivel is the portion of the opening where the slider stays against the bottom of the canopy, reducing your airspeed before the canopy starts to inflate. There will still be a lot of wind noise during the snivel, and you will still have a sensation of falling. This may last for a second or two, or even for several seconds.

The inflation occurs as the slider moves down the lines and the cells fill with air. Things become quieter once the canopy inflates. Even under a canopy that inflates very slowly and smoothly, you will still feel the transition from falling to gliding. You may also hear the slider flapping above your head once it comes down.

Once you become more aware of these sensations you will find that your other senses can tell you as much about your opening, if not more, than your eyes do. Soon you will feel comfortable looking out in front of you during the entire opening, rather than watching the canopy itself. This allows you to watch for other jumpers, and many people find this reduces off-heading openings as well.

“But,” you may ask, “if I don’t watch my canopy open, how will I know if I’m having a malfunction?” Take the advice of someone who has cut away a number of misbehaving canopies: you will probably know right away if you are having a malfunction. They tend to feel very different from a normal opening, and you will probably know something is wrong before you ever look up.

If you start to count after throwing your pilot chute, and reach “two thousand” or “three thousand” without feeling the snatch force, there is obviously a problem. This would be an acceptable time to look back over your shoulder and check for a pilot chute hesitation or pilot chute in tow.

Once you know how many seconds the snivel usually lasts on your canopy, you will also know if that part of the opening is taking longer than normal. You can usually feel line twists right away, and if you start spinning wildly you’ll surely want to look up at your canopy and see what’s bothering it.

What if the opening feels perfectly normal? Unless you need to avoid another jumper right away, you should still look up and check your canopy right after it inflates. You might not notice a tear, broken line, or similar problem until you look up. Even in these situations, if the opening felt normal then the canopy is probably flying well enough to give you a low rate of descent. Assuming you deployed at a reasonable altitude, you should have enough time to do a control check and execute emergency procedures if necessary.

If you’ve been watching your canopy open every time then you might not feel ready to stop doing this during your very next jump, but you should start developing better habits as soon as possible. Start counting when you throw your pilot chute, and notice how long each stage of the deployment sequence takes. Pay attention to what you are hearing and feeling during the opening. Soon you won’t need to watch the whole deployment, and will be able to pay more attention to your body and your surroundings.

Improving your body position and increasing your awareness when you deploy your canopy can produce great results. You might not remember everything in this article during your next jump, but at least think about trying these suggestions one at a time, at your own pace. You might be amazed by the difference a few small changes can make.

About the author: Scott Miller runs the Freedom of Flight Canopy School at Skydive DeLand in Florida (www.freedomofflight.tv) and holds canopy skills camps at other DZ’s throughout the year. He has worked at several drop zones as an AFF instructor, tandem instructor, and freefall photographer, and also worked as a test jumper for Performance Designs.

The standard flight pattern for a ram air parachute involves a downwind leg, a cross wind leg, and an into-the wind leg, also know as the final approach. This pattern is defined by three distinct turn points, “A” (Base to Final), “B” (Downwind to Base), and “C” (pattern entry point). It is true that if we are prepared to modify our approach in light of new information along the way, we can hit the target. But wouldn’t it be nice to get there without needing to modify our flight path, to just sail along and turn when the altitude is right? That is exactly what the inclusion of a fourth turn point does.

The trouble with the standard pattern is that there is a good deal of guesswork when it comes to the length of the Base leg. Depending on the glide ratio of the parachute, the location of the turn to Base leg will vary widely. The better the relative glide ratio, the farther the turn to Base needs to be from the target. Our ability to adapt to this changing environment is spotty at best, and often requires substantial correction along the way. This creates traffic conflicts, as well as varying airspeed and decent rate, making life far more difficult for us, and for the canopies behind us. In most cases, the length of the Base Leg needs to be longer than we think.

This becomes an even more important issue for swoopers setting themselves up for a high speed approach. If the length of the Base Leg is incorrect, the pilot is forced to either float in the brakes or “S-Turn” prior to the initiation of the dive. This has consequences to the approach, even if they manage to reach the Initiation Point at the correct altitude. If they are flying significantly faster than usual when they arrive at the initiation point, they may lose much less altitude in the turn due to the increased front riser pressure upon initiation. If they are flying significantly slower than usual, they may lose a much greater amount of altitude in the turn, and find themselves hooking into the ground. It is my experience that, aside from the altitude of the Initiation, the selection of the “B” point is the most important aspect of a high speed approach.

If we simply add another checkpoint prior to the entry into the Downwind Leg, we can take the guessing out of the process. Assuming that the turn points are equidistant in altitude (300, 600 and 900 feet), we can simply add another unit above the original pattern entry to create a fourth, or “D” point, precisely on the wind-line, upwind of the target. What this does is, it creates a Pre-Base Leg, which shows us exactly how long the Base Leg needs to be. In other words, if the altitude between the points is 300 feet, the “D” point is at 1200 feet.

The beauty of the data that this “D” point brings us is, we discover the exact length of the base leg without choosing the precise location of the “B” point prior to exit. This means that we can fly this pattern at a new drop zone, or when we are landing off, and learn where the altitude-location-checkpoints are for that specific landing area. It doesn’t help us with the “depth” of the pattern points, but it puts us in the ballpark, assuming that we have a rough idea of our canopy’s glide ratio.

When the winds pick up, this method still works perfectly well. The crab angle on the Pre-Base Leg is equivalent to the angle of crab on the Base Leg. Note that the horizontal distance of the offset from the target on the downwind leg on a windy day is exactly the same as it would be on a no wind day (A to B = Anw to Bnw). This is only true if we do not compensate for the side-slip of our ground track due to the crosswind legs.

However, even when we do choose to compensate for diagonal crabbing on the base leg and create a “Holding Crab”, if we create the same crab angle on the Pre-Base Leg, we end up on the perfect final approach despite the complex situation. This is easily accomplished by simply making our goal to fly a box pattern on the ground, flying our Pre-Base and Base Legs perpendicular to the wind-line.

Also note that the length of the base leg is longer on the No Wind condition than it is on a windy day on which we perform a Holding Crab on the crosswind legs. This is due to the reduced groundspeed when in a Holding Crab, and the diminished glide ratio that comes as a result of it. If you aren’t pointed where you are going, you will not move there quite as quickly.

This method assumes something that many canopy pilots do not have: a trustworthy altimeter. A standard dial-type, analog altimeter is not sufficient to give us the kind of accuracy we are looking for. Even the digital dial-type is not usually graded in such a way that we can distinguish units of one hundred feet or less. These are freefall altimeters. For the precise data required by today’s canopy pilots, we need digital altimeters with digital read-outs. Even better, many of us have found, is the heads-up advantage of an audible altimeter designed for canopy flight such as the Optima and Neptune. If you have an audible alert telling you where you are, it is far easier to keep your eyes looking outside the cockpit and on the action that may require your instantaneous reactions. All that being said, your eyes have ultimate veto power. If things do not look right, your instruments must be ignored. Too many skydivers have hit the ground due to complete faith in their instruments that let them down due to mechanical problems, battery issues or some unconsidered technical malfunction.

Assuming that you use this accuracy technique the way it was intended, and you notice what is happening as it is happening, you can take a huge step forward in consistently hitting your target runway. It will take a while to dial-in your approach so that you actually hit the target, but the target is always a secondary goal to hitting the centerline of the runway and turning to final at a reasonable altitude. If you plan your pattern well, using four distinct points along the way, you can change what you are capable of handling as a canopy pilot. Not only will you feel better about yourself, you will increase the likelihood that you will live a long, healthy life. That, of course, is the mark of a great skydiver.

In addition to being a highly experienced skydiver with over 14,000 jumps, Brian Germain is the author of several books including The Parachute and Its Pilot, Transcending Fear, Vertical Journey, and Green Light. He is currently designing canopies for Aerodyne Research, and offers canopy flight courses worldwide. For more about Brian’s Books, Seminars and Parachutes, visit his websites: www.BigAirSportz.com and www.TranscendingFear.com

Exit separation has become a point of contention at many DZ’s lately. Years ago, when belly flying was the rule and the Cessna 182 was the aircraft at most DZ’s, exit separation wasn’t too much of a big deal – you gave the other group (if there was another group) some time and then you went. With the aircraft in popular use 15-20 years ago, it was hard to exit very quickly to begin with, and so the issue never came up very often.

Bill von Novak started skydiving in 1991 at a small DZ in New York. Since then he has become an S+TA, an AFF, tandem and static line instructor, and has set two world records in large formation skydiving. He lives with his wife Amy in San Diego.

Since then, several factors have conspired to make exit separation more of an issue. First off, there are more people freeflying. Freeflyers, especially head down groups, drift differently than belly flyers, and thus need different considerations when planning for exit separation. Faster canopies mean that people who open facing each other need more distance to deal with a potential collision. Large aircraft with big doors can hold several larger groups, and those groups can get out those big doors more quickly. Finally, GPS spotting has removed some of the delay between groups. It’s rare to see people even check the spot before beginning their jam-up.

I first became aware of this issue in 1994, when I started jumping at Brown Field in San Diego. We went through a series of aircraft as we grew, from Cessna 206′s to King Airs to Beech-99′s, none of which had GPS. In addition, we were less than a mile from the US-Mexico border, which meant our jump runs had to be east-west and our spots had to be dead on. Several instructors were “designated spotters” and we would argue over 100 yard differences in jump run offset and exit location. After a while we got pretty good at spotting.

As our aircraft became larger, exit separation became more of an issue. We had a few close calls, and so we agreed to start allowing more space between groups. At first it was essentially trial and error – we would leave some amount of time (10 seconds or so) between groups and increase that time whenever someone felt they were too close to someone else. After a while, we began to get a feel for how much time was required. We knew that if the upper winds were strong and the plane was just creeping along the ground, we had to leave more time. We also knew that if we let the freeflyers get out first, we had a problem almost every time. We ended up with a system that worked for us, and had essentially no problems with collisions or close calls after that.

During this time I was also traveling in the summers to different boogies and I noticed a wide variety of exit separation techniques. By far the most common technique was some amount of fixed time – the next group would pause, then climb out and go, without knowing what the upper winds were doing or what the spot was. The next most common technique was similar but they added a “leave more time if it’s windy” clause to their delay. There was also a class of jumpers who looked out the door to tell how much separation to leave; these jumpers either looked at angle of the departing group or the ground to tell how much space to leave.

This got me thinking. What really works and what doesn’t? I tried a few methods on my own, from the “45 degree” method to a purely ground-based method. After some experiments, a group of skydivers collaborated via email and internet and came up with the actual math behind separation, the physics that determines how far the center of group A will be from the center of group B after they open. But before diving into the math, there are a few basic concepts to cover.

1. What we care about. When we’re talking about separation at opening time, we don’t really care about where we are in relationship to the plane or even the ground – what we care about is how far we will be in the air horizontally from the next group that opens. So for our purposes, the airplane and the ground don’t really matter, and someone watching from either of those places may not get the same “picture” of things that we get. (Of course, we do care about our relationship to the ground when it comes to spotting and landing on the DZ, but that’s a separate issue.)
2. How we fall. In most freefall (tracking dives and wingsuits excepted) we fall essentially straight down with respect to the air. If there’s wind, the wind blows us at whatever speed it’s blowing. If the wind is doing 30kts at altitude, a group of skydivers will be doing 30kts as they drift with the wind. It’s also important to realize how your trajectory changes after you open. At a freefall speed of 100kts, a 30kt wind will slightly deflect your trajectory, because it’s a small fraction of your total speed. Once under canopy and descending at 10kts, it will deflect your trajectory a tremendous amount, since it is now a very large part of your speed. Of course, under canopy you have much more control over your own horizontal speed, and the winds may add or subtract from your canopy’s groundspeed depending on the direction you are facing.
3. Speeds. When discussing speeds, it’s important to define units. There is feet per second, which is very useful for people who are trying to figure out how far they want to be from another group. At 100 feet per second, 10 seconds gives you 1000 feet, which is about as easy as it gets. You may also hear the terms indicated airspeed, true airspeed, and groundspeed, in both knots and miles an hour. These can all be converted back and forth as needed .

Now that all that’s out of the way, the math is pretty simple. The distance you will get between group centers is the speed of the aircraft plus the speed of the winds at opening altitude, multiplied by the time you leave between groups. That’s it. So if the aircraft is flying into the wind doing 80 knots per its GPS, and the winds at opening altitude are 10 knots from the same direction, and you are waiting 10 seconds between groups, you are going to get (80+10 = 90 kts, which is 153 feet per second) 1530 feet between groups.

It gets a little more complicated when the winds are not from the same directions. If the winds at opening altitude are opposite jump run, you have to subtract them rather than add them. If the winds at opening altitude are from the side, it’s the same as zero winds at opening altitude when it comes to separation.

If you put these equations into a spreadsheet and play with the numbers, some basic patterns emerge. If the headwinds at altitude are strong you have to leave more time. If the plane is slow (i.e. it’s indicated airspeed on jump run is low) you have to leave more time. If the winds at opening altitude are strong as well, and from the same direction, you can safely leave less time. (Or, preferably, just leave the same amount of time and you’ll end up with even more separation.) If the winds at opening altitude are opposite from jump run, that’s the worst case, and you have to leave even more time.

Some people have a problem visualizing how winds at opening altitude can possibly cause them trouble if they leave enough distance on exit. The question is usually phrased as “don’t all jumpers follow the same path out of the plane?” And they definitely do. To visualize why this can still cause you problems, take a look at the separation diagram shown below.

Drawing showing exit separations

In the first drawing, there is no wind after exit, and the first group breaks off, tracks, opens, and flies their canopies away from the center for the first few seconds, which is what they should be doing on most formation skydives. (After that, it’s a good idea to turn away from line of flight once you’re sure you are clear of others in your group.) The second group arrives 10-15 seconds later, shortly after the first group has opened their parachutes, with some room to spare.

The second drawing shows what happens when there are winds are the same all the way down. Notice that the “cone” caused by the breakoff and the canopy flight has shifted strongly to the right. This is because (as mentioned before) once their parachutes are open, the wind affects their trajectory more strongly. As with the first example, it is assumed that everyone flies away from the center for the first few moments. That means the jumper flying into the wind makes no progress and comes straight down, while the jumper flying downwind gets a boost in groundspeed..

The third drawing shows where you can run in to problems. In this drawing, the winds after exit are from the opposite direction. You get the same skewing of the cone, but now the edge of the cone is getting dangerously close to the trajectory of the next group. This is a case where the same separation at exit led to trouble because of opposite winds at opening altitude.

This leads naturally to the question “how much separation do you really need?” That depends on the group. 1000 feet should probably be an absolute minimum for any belly formation skydiving. That means that two four-ways can exit, fall straight down the pipe, track 300 feet from center on breakoff, and then still have 300 feet to deal with avoiding a potential collision after opening. With the speeds of today’s canopies, that’s a bare minimum. If the group size grows to two 10-ways, 2000 feet might be a wiser separation. If a low-time RW group backslides a bit, again, 1500 feet might be needed to be clear of them at opening time.

So how does a jumper who doesn’t want to carry around a calculator figure out how much time to leave between groups? One very simple way is to just look out of the plane and wait until it has covered 1000 feet, then go. This method, originally suggested by Skratch Garrison, takes much of the figuring out of exit separation. It can be hard to determine how far 1000 feet is on the ground, but fortunately most DZ’s come with a handy ruler – a runway. A 3000 foot runway allows you to put 3 groups out along its length with a bit of margin thrown in. This method also has the tremendous advantage that it requires people to look out the door, and that means they are more likely to see traffic, high canopies or clouds that could pose a hazard to their skydive.

Another simple way is time-based. There are several tricks you can use to determine how long to wait. One common one is to always leave at least 7 seconds, then if the upper winds are strong divide them by 2 and wait that number of seconds. (Faster aircraft sometimes use divide by 3.) So if the winds are 30kts you wait 15 seconds between groups. This technique uses some math but isn’t too bad.

A third technique that seems to be popular for some reason is the 45 degree method. In this method, jumpers wait until the previous group passes through an imaginary 45 degree line before they exit. The problem with this method is that the jumpers never pass through that 45 degree angle, or pass through it so quickly (under 1 second) that it’s not useful for determining separation. The numbers confirm this. What you see out the door depends purely on speed of the aircraft, fallrate of the jumpers and type of exit. If the plane is going slower than freefall speed, the group may start out above the 45 degree line, but will drop below the line in less than a second and never rise above it again. If the plane is going faster than freefall speed (which is rare) the jumpers stay above the line and never cross it at all. A good head-down exit will tend to move jumpers lower in the picture. Winds will not affect the picture; an exit in 5kt uppers looks the same as an exit in 50kt uppers.

There has been some friction over this issue. The 45 degree method has a lot of supporters because it’s so simple and makes a sort of intuitive sense. Beyond that, it actually seems to work for some people – although it’s likely that the extra time it takes to locate and stare at the previous group has something to do with the reason the next group usually leaves enough time. To show that this doesn’t work, two cameras were fixed at a 45 degree angle and mounted on a boom outside an Otter’s door (see pictures below.) Pictures and video of several jump runs both into the wind and downwind were taken and magnified to determine how close each group was to the imaginary 45 degree line, which was essentially the center of the images. The pictures confirmed the basic problems of the 45 degree rule. RW groups, falling a little faster than the aircraft, never quite passed behind the 45 degree line. Freeflyers, going much faster than the aircraft, stayed well below the 45 degree line for as long as they were visible in the stills (about 30 seconds.)

Some version of the 45 degree method may work for some people. It may be that the simple act of looking out the door delays them enough, or their subconscious may see the group moving slowly along the ground (because the aircraft’s groundspeed is low) and send a warning message to the rest of their brain – “hey, hold up a minute.” But waiting for a true 45 degree angle simply does not work.

Another issue that has become more important lately is exit order. Some places still put freeflyers out first, and that doesn’t make much sense. In 30kt uppers, a belly flyer who leaves 10 seconds and gets out after freeflyer will open 100 feet from him, but if the belly flyer goes first and the freeflyer leaves the same time he will open 2200 feet from the freeflyer. RW groups, since they are in freefall longer, drift farther downwind before opening. It seems like a no-brainer to choose an exit order that used this to your advantage and increased, rather than decreased, separation distances. You can certainly wait 20 seconds after the freefly groups before the belly groups exit if there is some other reason why the freeflyers have to exit first, but at most DZ’s it’s hard to ensure that 20 seconds, especially since waiting so long almost guarantees long spots or a goaround.

Below are two diagrams that show how exit order can affect separation.

Belly out first diagram

Freefly out first diagram

One reason given at DZ’s to explain a backwards exit order is that freeflyers open sooner and therefore are beginning to descend before the next group gets there. Bryan Burke of Skydive Arizona has pointed out that you simply cannot trust vertical separation – one premature deployment or malfunction and all that vertical separation is gone. Even during a normal skydive, when you add up altimeter error, pull timing and snivel distance, you can easily get a jumper opening 1000 feet from where he expected to be open. In fact, Bryan points out that at Skydive Arizona, the primary reason high pullers get out last is not for separation but rather because they are the ones that can make it back from a bad spot.

Every drop zone is going to have a different set of rules and a different approach to exit order. Some work well, some don’t work as well. Jumpers have to understand the factors that can reduce group separation so they can make informed decisions about when they want to exit and what kind of exit orders they are comfortable with.