INTRO

We recently heard about a couple of people having their (non ‘speed’) AAD activate while landing their Valkyrie, and after working on a press release about unwanted AAD activations we continued putting together some information from all the different AAD manufacturers.

This entire discussion about AAD activations under canopy is not new, and it is certainly not linked to any one canopy design or type of AAD unit. Indeed, someone may go up for a jump on student gear instead of their normal gear and dive the canopy in such a way that it surpasses the vertical speed of that particular AAD unit and causes a two out scenario. That’s why it’s important to understand your gear for each and every jump you do.

It’s also important to mention that we do not (nor do any of the AAD manufacturers) recommend that everyone just start jumping AADs with higher activation speeds. There are certainly trade offs with that to be aware of. For example, if you have a low speed malfunction, you will have to speed up that much more after you cutaway in order to reach the activation speed of your AAD unit. We also do not tell people whether they should or should not jump AADs. Simply that you should be knowledgeable about your gear options, make the risk/benefit calculations for yourself and make an informed decision about what to jump and when.

So what’s the deal with ‘speed’ units?

The discipline of canopy piloting and ‘swooping’ has come a long way. Today we see canopy pilots achieving higher speeds, jumping at much higher wing loadings on smaller canopies and doing more powerful turns than ever before. The skydiving community is also developing and producing canopies that are capable of much higher speeds. In 2005, there were a few instances of AAD activation during landing (with one resulting in a fatality*). Airtec, after working closely with the PD Factory Team, released the Speed CYPRES. For the purposes of this article, we gathered information from Airtec, Vigil and Mars who all offer units with higher activation speeds to accommodate high performance landings.

Should you get a Speed unit?

So what is it that dictates whether or not you should have an AAD with a higher activation speed? How do you know if you are close to reaching the activation speed of your AAD under canopy? Is it primarily the turn (how many rotations)? The wing loading or size of your canopy? Your skills/techniques doing high performance turns? The altitude of the dropzone? The weather? Or perhaps some combination of these factors?

It would be nice if we could just stop right here and say definitively “If you are doing more than a 270° turn on landing, with a wing loading above 2.0 on a canopy smaller than 120 sq. ft. you are at risk of activating certain AADs while under canopy”. The reality is, it’s not that simple.** Two jumpers, doing the same 270 at the same wing loading on the same canopy may get very different results (speed), due to their different subtleties in techniques.

However, there are ways to determine how close you are to activating your AAD while under canopy. Mars’ m2 has a ‘gravity index’***, and both Vigil and Airtec have data loggers that can gather information from your jumps to let you know whether or not you are close to activating your AAD while under canopy. It is possible to use instruments, such as the FlySight, to get an idea as to your vertical speed under canopy…but keep in mind this measures speed using GPS, while AADs calculate speed based on barometric pressure change (and, sometimes, a little of their own magic ). So there will be some variance.

Consider your options

If you can’t get a hold of something that will help you determine your vertical speed under canopy, please consider the following:

If you’re jumping a highly loaded canopy, a really small and fast wing, doing high performance turns or any combination of these factors…you should consider your AAD options very carefully. Many (if not most) skydivers using Expert AADs (with an activation speed of 35 m/s) will not be close to activating their AAD under canopy. And switching to a Speed unit (with an activation speed of 46 m/s), you may be throwing away a measure of safety…so think carefully about that choice.

As we said before, if you’re on student (or borrowed) gear and operating outside of the normal parameters for that gear, you could potentially activate your AAD under canopy. After a quick google search we found an AAD fire on a Velo 90 doing a 270, a Velo 96 at a 2.7 wl, a 103 doing a 720 and even a Crossfire at a 1.6 wingloading.

Below is a comparison chart, showing the different AAD units, their activation speeds and altitudes. For more technical information please read the AAD manufacturer’s manual and/or get in touch with them. If you have questions about your canopy, feel free to get in touch with us.

[easy table]Manufacturer,Mode,Activation Speed,Activation altitudes,Disarming Altitude

Airtec, Student Cypres, >29 mph<78 mph, 1000ft, 130 ft

Airtec, Student Cypres, >78 mph, 750 ft, 130 ft

Airtec, Expert Cypres 2, >78 mph (35 m/s), ~750ft, 130 ft

Airtec, Speed Cypres 2****, >96 mph (43 m/s), ~750ft, 330 ft

Airtec, Speed Cypres 2, >102 mph (46 m/s), ~750ft, 330 ft

Vigil, Student, >45 mph (20 m/s), <1300***** ft, 150 ft

Vigil, Pro, >78 mph (35 m/s), <1100 ft, 150 ft

Vigil, Xtreme, >96 mph (43 m/s), <1100 ft, 300 ft

Mars, m2 Student, >45 mph (20 m/s), <1085 ft, 195 ft

Mars, m2 Expert, >78 mph (35 m/s), <885 ft, 328 ft

Mars, m2 Speed, >101 mph (45 m/s), <885 ft, 490 ft

[/easy table]

*Experienced, world-renowned and highly respected skydiver, Adrian Nicholas, died on 17 September 2005 following an AAD activation during a high speed landing maneuver and a subsequent downplane.

**So far as we know, there is no clear set of parameters that any of the AAD manufacturer say will result in an increased risk of AAD activation under canopy (e.g: if you’re doing more than a 270, at a wing loading of 2.5 or greater, on a canopy smaller than 100 sq ft). And again, even if they declared set parameters, there are so many variables at play (including technique) that those parameters wouldn’t be set in stone by any means…

***The Gravity index is displayed as a percentage of reaching the activation point, with the activation point being 100%. After each jump, the pilot can display the Gravity Index value and determine their margin of safety for their particular canopy, wing loading, final turn radius, etc.

****As of 1/1/2013 Airtec increased the activation speed for Speed units. Any Speed CYPRES bought or maintained/serviced after 1/1/2013 has a higher activation speed of >102 mph (46 m/s). This was also around the time frame of the initial release of the Peregrine.

As of 1/1/2013 any unit bought or maintained/serviced has a ‘user selectable activation altitude’. This allows you to increase your activation altitude at the push of a button, in increments of 100ft, up to 900 ft. All CYPRES that do not have this feature will automatically be upgraded at their next maintenance, free of charge. You can also have your Expert CYPRES upgraded to a Speed CYPRES free of charge, if you so wish.

*****The programmed activation altitude for the Vigil units are set so that regardless of the jumper’s orientation to earth (belly or back) the unit will activate at a minimum of 840 ft. This accounts for the depression zone (burble) which results in a different activation height based on body to earth orientation.

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