1. A USPA Safety Day Presentation
How To Avoid
Canopy Collisions
A USPA Safety Day Presentation

2. Easiest Way? Jump Alone (OK, NOT Practical)
If you always jump alone, there would never be another parachute in the air to be concerned with. However, we seldom jump alone, so collisions are usually a factor we need to consider and avoid on every skydive when there is at least one other jumper in the air at the same time.
Jump Alone
(OK, NOT Practical)

3. Because Skydivers Like To Historically, The Two Greatest Risks Of A
Jump In Groups
Historically, The Two Greatest Risks Of A
Canopy Collision:
The two most likely places where a collision will occur is right after or during the main canopy deployment, or just before landing near the ground as jumpers all converge onto the landing area at nearly the same time.
Deployment
Landing Pattern

4. Deployment Separation Planning starts on the ground
Avoiding collisions starts with proper planning on the ground, before the plane even takes off. Everyone needs to be aware of the wind direction and speeds, jump run heading, group sizes and the time between groups based on the winds for the day.
Planning starts on the ground
BEFORE the jump

5. 1. Separation Between Groups
Two Considerations
Regarding Collisions up high
1. Separation Between Groups
2. Separation Between Jumpers
IN each group
Providing adequate separation between groups as well as separation between the jumpers in your own group are both critical factors in lowering the chances of having a collision during or right after deployment.

6. 3. Ground speed of aircraft
Group Separation
1. Type of jump
2. Size of group
Determing the separation between groups largely depends on these three factors; The type of jump-belly to earth or freefly, etc. The size of the group, and the ground speed of the aircraft.
3. Ground speed of aircraft

7. Group Separation Exit Order
Slow fallers (belly) largest to smallest
Fast fallers (freeflyers) largest to smallest
Students-solo gear first, then tandems
An established exit order that helps to promote group separation is as follows: Slow falling (belly) groups largest to smallest, Freefly groups, largest to smallest, solo equipped students, tandem students, jumpers deploying high for canopy work, and wingsuits.
High deployments
Angle Fliers, Tracking Groups, Wingsuits

8. Minimum Distance? 1. Canopy speed = 30 mph (44 feet per second)
2. Three seconds required to see and
respond to an approaching canopy
So how do you determine how much distance you need between groups? First determine what a minimum safe distance should be. Assuming that the canopy speed is 30 mph and it takes approximately three seconds to take action once it is determined that you are on a collision course with another jumper, the distance covered by two canopies flying head on would be approximately 300 feet in three seconds.
3. Two canopies on a head-on collision
Will cover 300 feet in three seconds

9. Minimum Separation 2 jumpers
150 feet
150 feet
Here is a graphic of that airspace requirement. Keep in mind that this would be the absolute minimum distance necessary to avoid a collision.
3 Seconds
300 feet

10. The corresponding area for an 8-way is more than 1,000 ft. across.
To obtain 300’ separation between jumpers in a 4-way, need to track 212 ft from the center so the individuals’ columns of air don’t overlap.
3 seconds after opening there could be canopies anywhere in an area 724 ft in diameter. Each group needs its own column of air.
Separation is achieved within the group by breakoff and tracking away from the center. Geometry shows that a track of 212ft minimum is needed by members of a 4-way to achieve 300ft separation – this when everyone tracks perfectly, with equal spacing. In actuality, accommodating imperfect spacing will require a longer track.
Since we don’t know a priori the directions in which group members will track, all we can safely say is that some 3 seconds after canopies open, members of the 4-way group with adequate separation between members can be anywhere within a circle 724 ft across (362ft in radius, the green circle in the figure). Of course, the area could be larger if members track farther. I shall call this the GROUP’S SPACE. Our aim, then, is to ensure adequate time or distance from one group to the next that one group’s space does not encroach on its neighbor’s group space. In addition to every individual needing his or her own column of air, each group also needs its own column of air.
724ft
The corresponding area for an 8-way is more than 1,000 ft. across.

11. Break-off and Deployment
Issues
Lack of separation from other jumpers
(Poor tracking skills)
(Low break-off altitude with less tracking time)
Followed By
Collisions among jumpers in their own group have typically been due to a combination of errors. For example a lack of separation from another jumper followed by an off-heading opening or an uncontrollable canopy due to line twist or having one brake release on opening.
Jumpers unable to control the parachute
after deployment
(Line twist)
(spinning canopy due to one brake release)

12. Distance Between Groups More distance is actually required
900 feet bare minimum
8-way group
4-way group
Considering an 8 way group followed by a 4-way group, the minimum distance necessary between the center of the two groups at deployment would be 900 feet.
This does not account for higher break-off, longer tracks, sliding groups
More distance is actually required

13. Distance Between Groups
For jump runs flown into the wind,
Ground speed of the aircraft is a large factor
The stronger the upper winds, the slower
the aircraft ground speed will be
Wait longer between groups with strong
upper winds
Upper wind and ground wind speed and direction all factor greatly into the time that is necessary between groups in order to provide adequate separation during deployment. For jump runs flown into the wind, the higher the upper winds, the more time that must be given between each group. With a ground speed of 30 mph the airplane will cover ½ mile in one minute.
Crosswind Jump Runs-Winds have less
influence on group separation
(Direction of ground winds will also play a large role in separation requirements)

14. Separation Chart In Aircraft
Inserting a separation chart near the door of the aircraft can help
provide guidance to jumpers for the necessary amount of time required
between groups.
Inserting a separation chart near the door of the aircraft can help
provide guidance to jumpers for the necessary amount of time required
between groups.

15. No deployment collision
Now what?
So now that you have created adequate airspace and your main canopy is open and flying, now what? You still need to maintain separation from other canopies during the descent and landing. Here are some things to consider during the canopy descent.

16. Orderly Flow Closest canopies pose the most
immediate threat of a collision
Identify the nearest traffic to determine
what needs to happen next
Once open, the most immediate threat of a collision comes from the canopies closest to you. This can be horizontal or vertical distance. Make sure to scan the area carefully, both above and below as well as horizontally. Be prepared to steer using rear risers immediately after inflation should there be a nearby canopy that is headed towards your own canopy.
Make adjustments that will help promote
an orderly flow of canopies towards
the landing area

17. Wing-loading plays a significant factor In maintaining separation
Try to remain near the same area
with your group
If you catch up to another canopy
During your descent, allow for
Plenty of room while passing
One you are clear of any nearby canopies you will need to plan the descent based on the current situation. This can change dramatically as you descend based on what the other canopies are doing. Higher wing-loaded canopies will descend faster and often pass other groups of canopies during the descent. Those who are passing other canopies need to respect he airspace of those other canopies and maintain a safe distance. Be aware that the lower jumper may not see you due to blind spots and may make a last second turn that can cause a collision if you are passing to close. If possible stay in the same airspace with your group so that the groups land in an orderly fashion and the landing area stays less corwded. Using rear risers or braked flight can slow the descent if it becomes necessary.
Be aware of blind spots
(above and behind)

18. Traffic Flow Landing Area Wind Direction
A good flow of canopy traffic will have the load separated into smaller groups approaching the landing area with a time separation to help prevent the landing area from getting crowded all at once.
Landing Area
Wind Direction

19. No wind? Pick a direction for landing and stick with it!
Traffic Pattern
Once above the landing area each group should be following an established traffic pattern, using left hand turns or right hand turns to final approach. This helps keep an orderly flow of canopy traffic all the way to landing, and nobody is cut off by canopies flying in different directions. If there is no wind, pick a landing direction for that load or for the immediate time being, and stick with it.
No wind? Pick a direction
for landing and stick with it!
Wind Direction

20. Split Landing Area
Sometimes it is necessary to fly an opposite landing pattern due to the exit point and it just makes sense to reverse the landing pattern instead of flying across the other canopies to try and get into the standard landing pattern. If you have to reverse the pattern, be sure to stay on the appropriate side of the landing area and watch carefully for other canopies. Especially at the base to final intersection.

21. Landing Pattern Issues
High-Performance approaches must
be separated from standard landings
Separate landing areas or;
By time, using separate passes for
H-P landings
Fly a predictable landing pattern
Defined Downwind-Base-Final
Straight-in final approach
Without S-Turns
USPA requires all Group Member drop zones to separate the high-performance approaches from those flying a standard landing pattern. This is done through space, with a separate landing area for high-performance landings, or through time, by providing a separate pass for high-performance canopies to land separately from those who are using a standard landing approach. S-turns on final approach have led to many fatalities in the past. Each leg of the landing patten should be flown in a predictable manner without using S-turns.

22. Canopy Collision Fatalities 1999-2016
Canopy collisions have typically resulted in several fatalities per year in the last decade. Immediately after deployment, and below 1,000 feet are the two areas where most collisions occur. The base leg to final approach intersection is one of the most common locations for a canopy collision. Jumpers need to stay vigilant and watch for traffic throughout the entire canopy descent.
Thanks to Professor John Kallend for use of his separation formulas!