Avoiding Conflict in our Airspace

With so many diverse areas of skydiving becoming popular, our chance of freefall or canopy collisions has greatly increased. Phil Webley discusses how we can effectively manage the space in our skies to avoid conflict…

In this article, I will discuss the safety requirements of various specialist disciplines within skydiving and how they can be performed safely as part of a regular DZ operation.

Curt Bartholomew once said that the downside to skydiving is, you have to rely on other people to not kill you. Today we have many skydive disciplines that have their own needs and characteristics. Everyone wants to perform their discipline without conflicting with each other. Our aircraft capacity as a sport is larger than ever and it means that routinely we have busier airspace. To add to that, we all need to land on the same PLA and manage traffic on the way there.

In this paper a number of disciplines will be discussed: 

1. high-performance landings
2. the debate as to whether freefly or formation skydiving groups should exit first
3. tracking and angle flying
4. solo freefly or coached jumps
5. disciplines which involve canopy deployment at unusually high altitudes, such as flocking, high pulls and canopy formations.

The main points I want to raise for anyone not versed in high-performance landings, is that the final turn is greater than 90°, the descent rates prior to landing are unusually high and when pilots perform these manoeuvres they can sometimes be blind to other parachutists. 

The most common manoeuvres are 270° turns as final approach and 450° turns. Manoeuvres with rotation larger than this are also possible. The altitudes can range from, 600 feet to 1500 feet where the pilots will reach vertical descent rate around 70 to 80 mph or more! The area used can be estimated to around 100 m x 100 m.

The introduction to high-performance landing areas in the UK (or “swoop lanes” elsewhere) has been a great move to separate regular landings from high-performance landings. It has served to separate landings by space and time and has reduced traffic issues. Although this is generally a great move by DZs, each one faces its own real-estate issues and each DZ has to work with what they have. Some HPLAs are small in size, requiring a relatively advanced pilot to safely land within it. This can put beginner and intermediate canopy pilots in danger as they are trying to land in small areas as well as learning the intricacies of high-performance landings. The considerations of some HPLAs sometimes turn out to be two-dimensional and concerned with deconfliction at ground level and there has been very little consideration three-dimensionally in the performance of manoeuvres and the approach to them on the base leg.

As an example: someone intending to execute a 270° turn while there is someone behind and below them making a regular approach may not see that jumper until they are already 180° into the rotation and reached a high vertical descent rate. See diagram 1:

It is almost always safer for high-performance turns which start at a higher altitude to extend beyond the regular PLA as in diagram 2:

If HPLA and regular PLA are in close proximity to each other, another method of deconfliction is to have the base leg approach of high-performance landings opposing that of regular landings. See diagram 3.

When this is not possible ensuring that the speed generating manoeuvre happens deeper (further downwind) of regular approaches and designating a no-fly zone is another good way of separating high-performance landings with regular approaches. See diagram 4

Different DZs choose to place freeflyers or formation skydiving groups first. Some baseline knowledge regarding the two disciplines from an exit order perspective involve forward throw and freefall drift. Freefly exits generally have about 50% more forward throw than flat flyers. It must be emphasised that to get this extra projection the freeflyers must be of a good level, whereas beginner free flyers may have a projection typical to belly flyers. In any case, this extra 50% accounts for around 80 metres more. The bigger factor is free fall drift, where flat flyers, as data indicates, have close to double the freefall drift of free flyers. In the conservative example of an average of 10 knots winds aloft, a formation skydiving group would have a freefall drift of 300 metres whereas a freefly skydiving group would be around 200 metres.

The traditional approach of formation skydivers exit before free flyers keep groups well away from each other by virtue of the fact that FS groups, which exit first drift further downwind and the free flyers after them will drift towards them but nowhere near as much. This method generally gives good horizontal separation and groups all open at similar times to each other. However, as the trend in skydiving tends to be now that the more experienced jumpers are freeflying and have smaller, faster parachutes and the less experienced (or older) jumpers tend to take part in FS and have slower parachutes. One disadvantage of this method is that the smaller faster canopies may overtake the slower jumpers in the pattern and the smaller, faster parachutes may open deeper, increasing the chance of an off-landing.

Some DZs have changed the exit order where all freefly groups exit first followed by all belly flying groups. This has seen great separation achieved where the free flyers with fast canopies have a combined faster descent rate such that they are much lower under canopy than the following FS groups by the time the belly flyers are deploying their parachutes.

Some other advantages which have come out from this method are that the faster canopies, which exit earlier, can deal better with a headwind if those jumpers exit short of the PLA and the slower canopies deal better with long spots flying back with a tailwind. The real disadvantage of this method is that FS groups can drift over the top of freefly groups when the freefall winds are particularly high, or at least to drift much closer than desirable to the freefly group which exited before. This occurrence could go by unnoticed for a long time until the rare – but not impossible – occurrence of a free flyer having a premature opening when an FS group has drifted over them. 

Nevertheless, this method has a lot of advantages in reducing canopy traffic so the above-named risks could be mitigated by ensuring that the first FS group following free flyers respects the required exit separation. As a guide, doubling the prescribed exit separation for the first FS group following free flyers would be a good recommendation. Some of these nuances may be missed by an inexperienced jumpmaster.

By their nature, these disciplines involve moving off the jump run. A lot of DZs will recommend to tracking groups to move in alternating directions and sometimes these tracking groups have vertical groups in between them in the exit order such as FS and FF further dividing and separating the groups.

In these groups, the jumper who has undertaken the responsibility of leading the group should have a good understanding of the winds aloft, jump run direction and general landmarks of the area. They must have a good understanding of the wind cone and ensure that they do not lead the group so far away from the PLA that they will not reach it under canopy. Some good control of these groups at various PTOs are: 

• only jumpers who have been vetted may lead tracking jumps
• there may be a limit of the number of movement groups on a particular lift 
• in the event that two groups cannot track in opposite directions but must both track in the same direction from jump run, an effective control measure is using a prominent landmark to divide the airspace for the two groups, ensuring the leaders keep their own group in their own portion of air space.

Canopy meeting points is a relatively new control measure: it is particularly useful on very steep angle jumps where the group won’t necessarily move very far away from jump run. The canopy meeting point is a designated area where, after opening the jumpers continue flying away from jump run and form as a loose canopy stack before then heading towards the PLA. This reduces the danger of multiple groups converging back onto jump run immediately once under canopy where it is easy to miss one stray jumper from another group. See diagram 5.

Someone still getting to grips with free flying who may not be falling “down the tube” can be moving horizontally at up to 30 mph. Over 40 seconds that can be a freefall drift of over 500 metres! Jumpers must receive a thorough brief on the importance of orienting their heading perpendicular to jump run – and jump masters should not be afraid to check a jumper’s understanding of the current jump run. It should be a high priority for coaches working with beginners to ensure that the two-way remains oriented perpendicular to jump run throughout the descent, so they move away from other skydivers.

The discipline of Canopy Formation  has been around for a long time, however there are newer disciplines emerging which require deployment at an unusually high altitude (even at full altitude). These disciplines make a DZ operation more difficult to manage, but not impossible. If a particularly high hop and pop has been dispatched, jumpmasters must take the descent rate of those canopies into consideration if the aircraft is to go around and dispatch free fallers on the same jump run. For example: hop and pops are dispatched at 10,000 feet, they have a descent rate of 1,000 ft/m, then the aircraft takes two minutes to climb to 12,000 feet and dispatch free fallers. The canopies from the first pass could still be as high as 8,000 feet, making the chance of a freefall/canopy collision a real possibility. 

Possibly dropping the high hop and pops on the way down after the free fallers could reduce that risk. Better still, the high canopies exit on the same jump run as the freefallers, negating the chance of freefallers being dropped over them. If high-pulls exit on the same pass, in light winds they will generally want to exit early (possibly their own green-light) and in high winds they will want to exit after everyone in a deep spot. 

The “glass wall” method of separation is the most successful where a prominent geographical feature (if linear, such as a runway, all the better) designates the separation between freefall jumpers and high-pull jumpers. Separate, offset jump runs for free fallers and high canopies on their respective side of the glass wall will further ensure separation, as well as briefing both parties. 

For those taking part in flocking, we can designate an altitude (for example 2,500 feet) before they can cross the glass wall or better still, if the PLA allows it, having a separate landing area for them. It is just as important for the freefall jumpers to be aware of these measures and not infringe on the glass wall either under canopy or in freefall, for example by tracking. See diagram 6 as an example of the use of a “glass wall”.

In summary, with a lot of new disciplines gaining popularity and large aircraft capacity we must have an open mind as to how we can accommodate everyone with maximum safety. Every DZ is different and under different constraints, so a lot of times we must work with what we have. Continue to reassess procedures and ensure that the de-confliction methods laid down will work in worst-case scenarios and not just best-case scenarios.