Skydive Mag is a free, international, online skydiving magazine with daily updates of news, event coverage, educational articles, safety information, videos and more

Loss of Altitude

by Performance Designs
by Performance Designs

A number of fatalities over the last few years have been caused by low cutaways following malfunctions, and there has been a lot of good advice on this issue as a result. But we recently had another tragedy in the big-way community from the same.

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. 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.

Take a normal skydive; let’s 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 – 400 feet? You are now at 2,600ft.

Keep your head up and look towards the horizon as you pull — by Marat Leiras
Keep your head up and look towards the horizon as you pull — by Marat Leiras

Altitude loss on deployment

Do you know how much altitude you lose on a normal deployment (without a malfunction)? Have you ever checked this? There are many different designs of canopies available and each with their own opening characteristics, those designed with a ‘long, medium or short snivel’. Whilst many of us will have a sense of which category our canopy falls into, do you know your actual altitude loss?

If not, watch your altimeter during your deployment sequence noting altitude loss from pulling your deployment handle to a fully inflated canopy. Let’s assume our altitude loss from deployment to fully inflated canopy is 800ft. You are now at 1,800ft with a fully inflated canopy.

by Scott Campos
by Scott Campos

But what if you have a malfunction?

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.

by Jump4Heroes
by Jump4Heroes

1. Do you know how much altitude you lose in an aggressive 360 degree toggle turn?

An aggressive toggle turn can be used as a replication of a toggle fire – 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)?

2. How much altitude do you lose on a slow 360 degree toggle turn?

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’t know the answer to this question, go try it – 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.

3. Are you now below your hard deck?

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 – here)

by Willy Boeykens
by Willy Boeykens
Sometimes the most minor malfunctions can result in a fatality due to this false perception and a loss of altitude awareness

Big-way community

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.

1. Assigned Deployment Altitude

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) – 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?

Brake line lock on Comp Velo 79… to chop or not to chop?…

2. Increased Weight

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?

It’s 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.

by Bill von Novak
by Bill von Novak

Summary

Being ready to participate in any event, big way or otherwise, requires being current in freefall and under canopy.

  • Know your system
  • Invest in the time to answer these questions so you can envision how the most important part of your skydive may unfold
  • Don’t be surprised by your altitude loss under difficult circumstances
  • Do the math and be ready to react quickly and decisively when needed.

Article by Maxine Tate of Flight-1 canopy school. Flight-1 run a range of courses in canopy skills, including exercises to understand altitude loss under various circumstances.

Zach Lewis had a bad day, relive it

Most Recent Articles

8-way, Block 6

Climbing & Jumping Castleton

Brilliant Pebbles - Audible Simplicity

Follow the leader

AOA For Dummies Part 2: Real World

Show more

Most Viewed Articles

Show more

advertisement

advertisement