{"id":16809,"date":"2014-12-30T00:00:00","date_gmt":"2014-12-30T00:00:00","guid":{"rendered":"http:\/\/skydivemag.com\/new\/?p=16809"},"modified":"2022-03-24T12:15:38","modified_gmt":"2022-03-24T12:15:38","slug":"2014-12-30-loss-of-altitude","status":"publish","type":"post","link":"https:\/\/www.skydivemag.com\/new\/2014-12-30-loss-of-altitude\/","title":{"rendered":"Loss of Altitude"},"content":{"rendered":"\n

A number of fatalities over the last years have been caused by low cutaways following malfunctions<\/h2>\n\n\n\n
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Malfunction image by Performance Designs<\/figcaption><\/figure>\n\n\n\n
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This safety article is not designed to give you answers; rather to ask you some very important questions, to which we hope you have the answers…<\/h3>\n\n\n\n
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If not then it is well worth the investment in time to find out. By having some key intel about your system (the combination of you and your canopy) you can dirt dive and visualise your deployment sequence to create a picture from deployment through to a steerable canopy. Whilst none of this is a substitute for altitude awareness on the jump, a good solid picture of how much altitude you lose in various scenarios can be a powerful tool in knowing how a particular jump may unfold and how important it is to make a swift decision.<\/p>\n\n\n\n

Losing Altitude <\/h2>\n\n\n\n

Take a normal skydive; let\u2019s say you have a chosen deployment altitude signal of 3,000ft. Reaching for the handle: you respond to an audible alarm or a visual check of your altimeter\/ground, you check for clear airspace, wave off and pull. That sequence may take 2 seconds before you touch your deployment handle. How much altitude have you lost \u2013 400 feet? You are now at 2,600ft.<\/p>\n\n\n\n

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Altitude loss on deployment<\/h2>\n\n\n\n
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Image by Parasport Italia<\/figcaption><\/figure><\/div>\n\n\n\n

Do you know how much altitude you lose on a normal deployment (without a malfunction)?<\/strong><\/p>\n\n\n\n

Have you ever checked this? There are many different designs of canopies available and each with their own opening characteristics, those designed with a \u2018long, medium or short snivel\u2019. Whilst many of us will have a sense of which category our canopy falls into, do you know your actual altitude loss?<\/p>\n\n\n\n

If not, watch your altimeter during your deployment sequence noting altitude loss from pulling your deployment handle to a fully inflated canopy. Let\u2019s assume our altitude loss from deployment to fully inflated canopy is 800ft. You are now at 1,800ft with a fully inflated canopy.<\/p>\n\n\n\n

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Malfunction \u2013 photo by PD<\/figcaption><\/figure>\n\n\n\n

But what if you have a malfunction?<\/h2>\n\n\n\n

Altitude loss during a malfunction: whilst we cannot simulate various malfunctions to measure altitude loss, we can better understand the rate of turn of our system and the altitude loss associated with it.<\/p>\n\n\n\n

1. Do you know how much altitude you lose in an aggressive 360 degree toggle turn?<\/h2>\n\n\n\n

An aggressive toggle turn can be used as a replication of a toggle fire \u2013 how much altitude do you think you would lose after three rotations (a reasonable estimate of the rotations needed to release the other toggle and regain symmetry back under the wing)?<\/p>\n\n\n\n

2. How much altitude do you lose on a slow 360 degree toggle turn?<\/h2>\n\n\n\n

For example you release your toggles and one is snagged\/has a small knot that you try to clear. The rotation is slow, the perception may be that you have enough time. If you don\u2019t know the answer to this question, go try it \u2013 the results may surprise you. Sometimes the most minor malfunctions can result in a fatality due to this false perception and a loss of altitude awareness.<\/p>\n\n\n\n

3. Are you now below your hard deck?<\/h2>\n\n\n\n

You were around 1,800ft before the malfunction. In any of the above circumstances is the altitude loss enough to put you below your hard deck, ie the altitude under which you will not cut away your main canopy? If not, how much altitude do you have as a buffer to make a decision? If it is, then you may question your deployment altitude or your choice of canopy. (Hard Deck Discussion by Shannon Pilcher of Flight-1 \u2013 here<\/a>)<\/p>\n\n\n\n

Sometimes the most minor malfunctions can result in a fatality due to this false perception and a loss of altitude awareness”<\/p><\/blockquote><\/figure>\n\n\n\n

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Photo by Willy Boeykens<\/figcaption><\/figure>\n\n\n\n

Big-way community<\/h2>\n\n\n\n

All of these questions above relate to any jump under normal circumstances. For the big-way community out there, we find ourselves in situations where circumstances must change in order to meet the demands of the jump or the slot.<\/p>\n\n\n\n

1. Assigned Deployment Altitude<\/h2>\n\n\n\n

We are often given a ceiling and a lower altitude in between which we must deploy for safety reasons (e.g., deploy between 3,000 and 2,800ft) \u2013 our deployment altitude is set for us. If you run through the math above for your set deployment altitude, what effect does that have on your window of safe opportunity to make a decision in the event of a malfunction?<\/p>\n\n\n\n

2. Increased Weight<\/h2>\n\n\n\n

We may have to wear 20lbs of lead to be in our mid fall rate range for our slot. This increases our airspeed under canopy as well as our freefall speed. That in turn will increase the loss of altitude on deployment and during a malfunction. By how much?<\/p>\n\n\n\n

It\u2019s vital for us to understand altitude loss with our current system, and it is important to appreciate how this will change when we alter any aspect of the system, such as wearing weight or changing canopy. If you may require weight at a record event, then go experiment with your canopy with that weight before the event. Know the answers to these questions and give yourself a clear heads-up of how it may affect that small window of opportunity to make the right decision. You will also benefit from the repetition of landing with a greater wing-loading than you are used to.<\/p>\n\n\n\n

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Photo by Bill Von Novak<\/figcaption><\/figure>\n\n\n\n

Summary<\/h2>\n\n\n\n

Being ready to participate in any event, big way or otherwise, requires being current in freefall and under canopy.<\/p>\n\n\n\n