What is your Decide and Act Altitude?

? – Do you have a Decide and Act altitude ?
? – Do you have a Hard Deck altitude ?
? – How do you decide these altitudes ?

In 2018 I published an article called “The Malfunction Flowchart” in an attempt to summarize the most common nuisance factors and malfunctions and the appropriate reactions on one page so that jumpers have a visual aid to review and hopefully practice their emergency procedures regularly.

While the feedback was mostly positive, to my surprise there were a number of people on various channels of social media who seemed to be disturbed by the “Decide and Act” altitude of 2500 feet I chose to adopt in the graphic (altitude recommended for students by the USPA).

Most comments went along the line of “…and I should ride it down to 2,500 feet till I react, or what?” I shrugged it off as people just being keyboard warriors, patted myself on the back for making skydiving safer and forgot about it.

Until recently when I gave a talk about canopy collisions, where I was met with blank faces when I asked about people’s Decide-and-act altitude and their hard deck. Turns out a considerable number of skydivers have not considered, let alone set these altitudes for themselves. It is after all a complex topic with A LOT of factors influencing your decision, which can of course lead to information paralysis.

That, or people just don’t like to think of worst-case scenarios, let alone complex ones and their solutions.

Either way, given that in recent years we have seen an increased number of fatalities due to low cutaways, I am going to take you down the rabbit hole of a caffeine-fueled rant about the Decide and Act Altitude. 

All About Altitude

What we will discover is the following:

• What is the Canopy Hard Deck?
• What is the Decide and Act Altitude?
• Why a clearly defined Decide and Act Altitude is a good idea
• Factors you need to consider when choosing your Altitudes

What I will NOT do is tell you which altitude is right for you. 

I will do my best to describe all the influencing factors in my case, show a few hypothetical scenarios, and then hopefully you will find yourself urged to clearly define your Decide and Act Altitude as well as your hard deck and maybe revise your standard pull altitude in the process.

What is the Hard Deck?

Briefly put, your canopy hard deck is the altitude from which, once reached, you do not cut away from a malfunction any more since below that altitude it is not considered safe. As Shannon Pilcher said in an interview (in video at base of article): “Once you’ve reached your hard deck, your right side is out of the equation and you directly jettison your reserve.”

The hard deck implies that you have entered the stage of ‘Last resort’ of your EPs.

Usually, the 1,000 feet mark is chosen as ‘do not cut away below’ altitude and 0-1,000 ft. is clearly marked in red on most analog altimeters. The reason for this altitude is its proximity to the ground – approximately 5.5 seconds to impact at terminal velocity, and the impending AAD activation – approximately 750 ft. for Expert CYPRES.

Shannon Pilcher suggested in a Performance Designs Raw talk to link a strong reference such as the pattern entry point or the point of maneuver for high performance pilots to the hard deck altitude, so that the course of action is clear in case of collision or malfunction during the pattern.

Decide and Act Altitude

Your “Decide and Act Altitude” is a clearly defined altitude which acts as a safety buffer before you reach your hard deck. As the name suggests, it is the altitude by which you should decide and act in case of a malfunction or uncertainty of a landable parachute.

This is the altitude at which nuisance factors, if unresolved, turn into malfunctions, and require the execution of your Emergency Procedures (EPs), immediately.

This is a ‘Decide and Act LATEST BY…’ altitude, as in “if you haven’t yet, now you must carry out your EPs”.  If you are above your ‘Decide and Act Altitude’ and it is obvious that you have a malfunction, do not delay your emergency procedures unnecessarily.

If you are above your ‘Decide and Act Altitude’ and you have a malfunction, do not delay your emergency procedures”

You should choose this altitude low enough below your pull altitude to allow for the opening process and address a possible nuisance factor as well as execute a full controllability check. Also, you should have enough margin below this altitude to not risk AAD activation during your emergency procedures and allow time to choose a safe landing area under your reserve, once it’s deployed.

In order to avoid confusion and too many different altitudes, I use the same “Decide and Act Altitude” under parachute to confirm that I can in fact land on the dropzone or commit to an alternate landing area when I’m flying home from a long spot.

What influences the choice of these altitudes?

Looking over my skydiving career so far, I noticed something in my choice of pull altitude as depicted in fig. 1, and I realized that I was not alone in this trend. Many of my full-time colleagues and more experienced friends showed a similar tendency over the course of their time in the sport.

Why was that?

I have always enjoyed flying high performance wings, so naturally as I downsized, my wing loading increased and my housekeeping got more complex (Removable slider, chest strap extensions, camera wings, etc). I chose to pull higher. I did this to adjust for higher descent rates of a smaller parachute, guarantee my point of maneuver for the turn and get the upper hand in traffic, as well as gaining time to react in case of a malfunction.

On top of that, by this time I was working full time as TI, AFF-I and camera flyer and had had a taste of the occasional long spot with a side of spicy outs after exiting last and openings taking longer than comfortable.Then I started traveling for load organizing jobs, jumping at unfamiliar dropzones, with out-landing options of varying degree of quality and the occasional close call that comes with the job description.

This led me to set my AAD activation altitude higher, to decrease my chances of hanging under a reserve with nowhere to land, same reason I have always jumped a skyhook. On a side note, the fact that people are starting to set their AAD activation altitude higher is a trend I welcome, but as mentioned before, this has consequences for your (1000 ft) Hard deck, as well as your “Decide and Act Altitude” as we will see in a little bit.

All of these factors made me review my previous choices for opening altitudes, “Decide and Act Altitude” and hard deck. I was asking myself some sobering questions:

• How low am I comfortable being under my reserve? 
• What if I have line twists in my reserve?
• How long does it take me to execute my EPs? 
• How does that translate to altitude?
• What does that imply for my “Decide and Act Altitude” if I have a high-speed malfunction and I travel at close to terminal velocity?

How much time do you have?

For the next part, keep the following information in mind for reference:

• If you are having a high-speed malfunction, you’re traveling close to terminal velocity 
• A spinning malfunction can generate considerable descent rates
• If you are current, your EPs will take approximately 3-5 seconds to execute from point of decision, factoring in a possible minor complication (hard reserve pull, difficulties due to high G-force on a spinning malfunction, equipment hindrance eg, wingsuit, etc)
• In case of a collision or a high-speed/high G-force malfunction, it is easy to get overwhelmed. Your inner clock might not be as reliable as usual and altitude awareness is lost easily

For example, the approximate Time vs. Altitude lost at 120 mph is:

• 10 seconds loses 1,800 feet
• 8 seconds loses 1,450 feet
• 5.5 seconds loses 1,000 feet
• 2.5 seconds loses 450 feet
• 1 second loses 180 feet

This example is for a skydiver with 200 lb exit weight. Speeds vary by size, weight, clothing, maneuvers, etc.

Visualizing Altitude Lost

Following are three graphs that will help you visualize how much altitude (and as a result time) you effectively have at your disposal if you pull at 3,000 ft, 3,500 ft and 4,000 ft. This assumes that you lose 600-1,000 ft during your deployment, considering three options:

• Option A: Ride the malfunction down till your hard deck (high risk of AAD fire)
• Option B: Have a Decide and Act Altitude of 1,500ft.
• Option C: Have a Decide and Act Altitude of 2,000ft.

Each with a standard AAD activation altitude A0 (A0 = 750 ft +250 ft safety margin) and a commonly-chosen higher activation altitude A3 (A3 = 1050 ft +250 ft safety margin) as reference):

With all the information we have discovered so far, you will now be able to see how much altitude you have to execute your EPs if you ride it down to these common ‘Decide and Act Altitudes’ in each of the cases and how much altitude you have left after until your hard deck.

Remember these graphs are there to help visualize the implications of altitudes that are often chosen without second thought to the possible consequences. They are supposed to help you make an educated decision that could potentially prevent a life-threatening situation. Under no circumstance are these graphs to be seen as an invitation to stay with malfunctions for a second longer than necessary.

Option A

Ride the malfunction down till your hard deck (high risk of AAD fire)

Option A – This Graph serves to establish a baseline, depicting how much time you would hypothetically have with no ‘Decide and Act Altitude’ until you are running a high risk of your AAD activating. An AAD activation is a last resort and should be treated as such. I do not recommend or endorse waiting until AAD activation by any means.

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Option B

Have a Decide and Act Altitude of 1,500 feet

Option B – This graph shows approximate altitudes from opening until an established ‘Decide and Act Altitude’ of 1,500ft, as well as the altitude left from decision until high risk of AAD activation for different presets of AAD activation altitudes, A0 and A3.

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Option C

Have a Decide and Act altitude of 2,000 feet

Option C – This graph shows approximate altitudes from opening until an established ‘Decide and Act Altitude’ of 2,000ft, as well as the altitude left from decision until high risk of AAD activation for different presets of AAD activation altitudes.

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Influencing factors

In the three graphs above, as complex as they might seem, it is important to keep in mind that they are still a simplification of reality. When you choose your ‘Decide and Act Altitude’ take into consideration the list of contributing factors and questions below, as they will influence the altitudes you select. It is a good idea to revisit this list regularly, especially if some of the factors change, and ask yourself if your altitudes should remain as they are, or if they need to be adjusted accordingly.

Influencing factors

• Currency
• Emergency Procedure currency
• Pull height
• Altitude loss during opening
• Canopy size
• Canopy design
• Wing loading
• Reserve size
• Reserve wing loading
• Selected AAD Activation Altitude + (250 ft. safety margin)
• Skyhook/RSL/none
• Equipment choice (wingsuit, camera wings, weight belt, Mutant etc.)
• Equipment familiarity
• Dropzone: familiar – unfamiliar
• Available outs

Questions

• How low are you comfortable being under your reserve?
• What if I have line twists in my reserve?
• How long does it take me to execute my EPs?
• How does that translate to altitude?
• Implications in case of high-speed malfunctions?

Side-by-Side

In this last graph below, the three options of chosen Decide and Act Altitude – none, 1,500 feet and 2,000 feet – and their implications on relative altitude to resolve any issues until the respective altitudes are reached is shown relative to a standard pull altitude for reference.

This is not to promote this deployment altitude over another, but serves to see the three options in a very common scenario relative to each other.

Options A-C

Side-by-Side

Conclusion

These graphs are a tool to visualize the implications of the altitudes you select and help you evaluate the cost and benefit of your decision.  There is no black and white here and as complex as these graphs are, they are still a simplification of reality. Some of you will look at these graphs and recognize their own patterns and reconsider their choices, or you might find that you were right on the money.

It is important to be aware of the influencing factors, the complexity of the situation, and the implications of your choices of your Hard Deck and ‘Decide and Act Altitude’.

Be aware of influencing factors, complexity… and implications of your choices of your Hard Deck and “Decide and Act Altitude”

Make an educated choice

In the end I want to leave you with the tools to make an educated choice with the information you need at your disposal. Each skydiver should choose the altitudes they deem adequate for their skill level and be aware that as the determining factors change, so can and should the altitudes.

When choosing your altitudes, pick round, easily recognizable numbers, commit to them, back them up with audible alarms and review them regularly.

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Note: ‘Decide and Act Altitude’ is referred to as ‘Decision Altitude’ in some countries. We prefer ‘Decide and Act’ because it’s important to act – ‘Decision’ does not mean Action’.

Sources:

1, Shannon Pilcher discussion on Canopy Hard Deck

2, Cypres2 User Manual

3, Cypres Terminal Velocity Chart