Determining Your Minimum Opening Altitude
How low should you go?
Whether you’re new, or just haven’t thought about it since you were–it’s time to give that question a good mulling-over.
Determining your minimum opening altitude is an important decision that every jumper must make. That said, it’s not as simple as looking at USPA BSR’s (or any other national organisation’s regulations, for that matter). Why? Well: you don’t always get to choose. Since your AAD might someday be handling the deployment, you need to make sure it knows your wishes–and that those wishes are damn well informed.
Over the last decade, an average of two jumpers per year have died after an AAD activation of their reserve parachute at an altitude that was insufficient for a full reserve deployment. The expert consensus is that many of these fatalities could have been avoided with higher AAD activation altitude settings. Given the estimated 200 to 300 AAD saves per year, there’s a greater-than-99% chance that your AAD will save your life if you fail to activate your parachute; however, close to 1 in 100 AAD riders do not survive due to the reserve not being fully open above ground level.
AAD settings: the fundamentals
While the factory setting of the Sport CYPRES (750ft AGL) and the Sport Vigil2 (840ft AGL) are high enough to prevent a fatality in the vast majority of cases, there are some cases where the reserve deployment process takes more altitude than available. These longer deployments could be caused by a number of factors. Keep in mind that with typical freefall speeds of 200 feet/second, a one-second hesitation between the AAD activation and reserve inflation could result in a fatality: maybe, yours.
Both Cypres and Vigil AAD’s have the capability for users to set higher than the activation altitudes set at the factory. To determine if you should or should not alter your activation altitude, reassess four critical altitudes for each jump:
the planned main parachute deployment altitude
the minimum main parachute deployment altitude
the minimum cut-away altitude, and
the minimum reserve deployment altitude (AAD activation altitude)
AAD settings: what to ask yourself
Minimum altitudes will change as equipment changes and with your vertical speed when deploying. To arrive at your planned main deployment, minimum main deployment, cutaway, and reserve deployment altitudes, you need to calculate from the ground up.
In order to make your choices here, there are a few self-inquiring questions we like to use as lenses. Here goes:
If you have an AAD activation, how much altitude do you want to have under your canopy to (potentially wake up and) prepare to land?
How much altitude would give folks on the ground the optimal amount of time to grok your situation and hop into a chase car?
Can you land your reserve with no flare and not get hurt?
Do you want to be able to unstow the brakes and let the canopy build up some speed for a flare?
Do you want to be able to also turn into the wind or have a chance of avoiding obstacles?
Do you really want your AAD set so close to the edge that a one second pilot chute hesitation could be the difference between life and death?
Keep in mind that, at the lowest AAD settings, you may not have enough time to manoeuvre the canopy into a clear area, set up an approach and/or get in a solid flare. This fact alone presents good reason to raise the AAD setting to close to 1000 feet AGL (or more).
It’s important to keep in mind that your AAD factory altitude setting is its minimum activation altitude. According to both Cypres and Vigil, your AAD unit could fire up to 260 feet higher than the setting, depending on the circumstances. That means that, given the factory settings, both Cypres’ and Vigil AADs may open as high as 1010 and 1100 feet, respectively. If you raise your AAD activation altitude to 1000ft AGL, your AAD could fire as high as 1260ft AGL.
Minimum cutaway altitude: what to ask yourself
Here, we figure out how much altitude you need to perform your emergency procedures (EPs). Many skydivers are taught to think of this as their “decision altitude.” There are a few factors to consider when determining this number:
Do you want to leave yourself time between cutting away and pulling the reserve to get into a stable belly-to-earth orientation?
How much altitude do you want to set aside for unforeseen circumstances?
What if you reach for your cutaway handle and end up with a handful of jumpsuit?
What if you have a hard time breaking the Velcro loose, or your cable hangs up in a poorly-maintained housing?
What if the risers do not release immediately?
Could you handle these situations in four seconds? Three? Two?
Once you have determined how much altitude you want for your EPs, you can then calculate your minimum deployment altitude.
Minimum main deployment altitude: self-inquiry
When determining your minimum deployment altitude, consider the following:
How long does your canopy snivel?
After that, how long will it take you to decide whether to keep your main parachute or cut it away?
If you have a small high-performance canopy, you could be losing altitude very quickly in a malfunction. Will you fight the malfunction or cut away immediately?
Let’s take a look at an example.
Jumper Joe has his AAD set to activate at 750ft AGL, meaning that the AAD could fire as high as 1010ft AGL. He believes this AAD setting leaves him enough time to find a clear landing area and flare under his large reserve. Jumper Joe wants at least 500 feet to perform his emergency procedures and account for any unforeseen circumstances like a hard pull. His canopy usually snivels for about 600 feet. If he has a malfunction, he wants to leave himself enough altitude to at least assess the situation and make one attempt to solve it. He will leave himself 400 feet to do this.
By adding these altitudes together, Jumper Joe can determine that his minimum opening altitude is 2510 ft. AGL.
These altitudes are constantly in flux and must be re-evaluated for every condition, including canopy size and type, jumper experience level, and location. (Are you jumping in the desert at sea level, or are you jumping at a DZ with a high ASL and surrounded by trees?)
They also need to be regularly adjusted relative to each other. If you decide to change one altitude, all other altitudes will be affected. For instance: if you change your AAD setting from 750ft to 1000ft AGL, you’ll need to bump every other altitude up by 250 feet to allow yourself a sufficient amount of altitude to deal with a situation. Failure to raise these other altitudes could result in having two canopies out–and, of course, main><reserve entanglement increases your chance of injury or death. Eek.
Planned main deployment altitude: setting a strong foundation
Finally, it’s important to give yourself a buffer between your minimum opening altitude and your planned opening altitude.
What happens if your rig shuffles around your back on a jump, the hackey isn’t exactly where you thought it would be and it takes you a second or two to find it? Experienced jumpers should have at least a 500-foot safety buffer here: so, if Jumper Joe’s minimum deployment altitude is 2510, his lowest planned deployment altitude should be no lower than 3010ft AGL.
Conclusion
Even though AADs have a very impressive safety record over the years, it remains the responsibility of every jumper to ensure their safety margins are maximized.
Each jumper must carefully consider their planned main deployment altitude, minimum main deployment altitude, minimum cutaway altitude and minimum reserve activation altitude for their particular situation. These decisions could make the difference between life and death.
We’re here for you if you need more advice on this important matter. Please don’t be shy: contact us.
Author: Bill Cou
Bill Coe is the Owner and President of Performance Designs, Inc. Performance Designs was founded in 1982 and it is the realisation of Bill’s dream to deliver improved performance of ram-air parachutes to the sport of skydiving. Bill’s passion ignited following his first jump at the age of 18 in 1976 and burned fiercely. He relocated to chase year-round jumping, but was dissatisfied with the canopies he encountered. First modifying, then building new designs from the ground up (all self-funded), he set out to revolutionize the sport and did so with the release of an early version of the PD 9-cell from his shop in DeLand, FL. Bill’s friend and also ardent skydiver, John LeBlanc, matched Bill’s passion and drive for moderniced designs and joined PD as VP. With their combined efforts, the company thrived, yielding cutting-edge developments such as Microline, cross-bracing, and zero porosity fabric, all of which endure as standards in today’s parachute industry. Today Performance Designs calls DeLand, FL home, where Bill and John continue to lead and inspire their team to create progressive designs, and still encourage lunch break skydives.
By: Performance Designs & Bill Coe
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