This article was written by PD’s President Bill Coe in 2016 for the PD blog and is still relevant today…
Determining your minimum opening altitude is an important decision that every jumper should make
It’s not as simple as looking at USPA, BSR’s or other national organizations’ regulations…
Over the last decade, an average of two jumpers a year have died after an AAD activation of their reserve parachute at an altitude that was insufficient for a full reserve deployment.
It is likely that many of these fatalities could have been avoided with higher AAD activation altitude settings. There are an estimated 200 to 300 actual AAD saves per year, so you have 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 do not survive due to the reserve not being fully open above ground level.
Both Cypres and Vigil AAD’s have the capability for users to set higher than factory setting activation altitudes. 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)
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.
Minimum Reserve Deployment Altitude (AAD Setting)
If you have an AAD activation, how much altitude do you want to have under canopy to prepare to land? 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? You should know how much altitude after opening it takes to safely land your reserve. At the lowest AAD settings, you may not have enough time to maneuver the canopy into a clear area, set up an approach, or get a good flared landing. This alone would be good reason to raise the AAD setting to close to 1,000 feet AGL or more.
While the factory setting of the Sport CYPRES (750ft AGL) and the Sport Vigil2 (8,40ft 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 things. Keep in mind that with typical free-fall speeds of 200 feet/second, a one second hesitation between the AAD activation and reserve inflation could become fatal. 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? It’s likely that some of these deaths could have been prevented if the AAD were set to activate closer to 1,000 ft AGL or more.
It’s important to keep in mind that your AAD altitude setting is 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 with the factory settings Cypres and Vigil AAD’s may open as high as 1,010 and 1100 feet respectively. If you raise your AAD activation altitude to 1,000ft AGL, your AAD could fire as high as 1,260ft AGL.
Minimum Cutaway Altitude
How much altitude do you need to perform your emergency procedures (EPs)? 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 in 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 also get a handful of jumpsuit? What if you have a hard time breaking the Velcro lose or pulling the handle? What if the risers do not release immediately? Could you handle these situations in 2, 3 or 4 seconds? Once you have determined how much altitude you want for your EPs, you can then calculate your minimum deployment altitude.
Minimum Main Deployment Altitude
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 at activate at 750ft AGL, meaning that the AAD could fire as high as 1,010ft 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 2,510 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 or are you surrounded by 100ft tall trees?). If you decided to change one altitude, the other altitudes will be affected. For instance, if you changed your AAD setting from 750ft to 1,000ft AGL, every other altitude would have to be bumped up by 250 feet to allow yourself a sufficient amount of altitude to deal with the situation. Failure to raise these other altitudes could result in having two canopies out. A main/reserve entanglement increases your chance of injury or death.
Planned Main Deployment Altitude
In any case, it’s important to give yourself a buffer between your minimum opening altitude and your planned opening altitude. What happens if the ripcord or pilot-chute handle is not 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 2,510ft, his lowest planned deployment altitude should be no lower than 3,010 feet.
Even though AADs have a very impressive safety record over the years, it is 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 the life and death.
Article written by Bill Coe, originally published in 2016 on the PD blog
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- Four Critical Altitudes - 19th February 2021
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