AOA For Dummies Part 2: Real World
Second installment of Angle of Attack video education for wingsuit BASE jumpers
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While no one can exempt themselves of this risk, there are a number of things you can do to reduce the chance of getting near a wall, or hitting it.
Off-heading openings are a common occurrence and quick, decisive action is necessary to bring yourself back on heading, but let’s have a look at what causes off heading openings:
While your pack job can have an adverse effect on the opening it is by far the least likely cause unless you´re a sloppy packer not paying attention to symmetry. A symmetrical pack job that lifts the parachute with equal distribution of weight out of the container facilitates an on-heading opening. Make sure to check that your bridle and center cell are indeed centered and flaking of the material folds etc are equal on both sides. All other factors such as wind and body position being perfect, your symmetrical pack job will likely open on heading.
The body position before and during the deployment, as well as your forward speed can have great effect on heading performance. The rotation of your body once the risers load can range from nearly 0° (extreme head high) to 180° (extreme head low). While a head high, arched deployment rotates from riser load to sitting in at about 90°. In addition, depending on your forward speed at deployment, the canopy can be extracted from straight up at 0 forward speed to somewhere at 45° behind you, if you were tracking fast. If your line-stretch results in one riser loading before the other the canopy starts to inflate and fly on one side before the other. Your body´s attitude and speed can have a negative effect on the rotation and the subsequent inflation of your canopy.
Windy conditions can have great effect on the deployment and heading performance.First the placement of your pilot chute and its position relative to your container upon bridle stretch can pull the canopy to one side during deployment. Vented pilot chutes have better performance to stay behind your back though strong wind from one side can pull the deploying parachute to line stretch. Once the pins are popped and the mess you called a symmetrical pack-job lifts out of the container. It is then exposed to the relative wind comprising of your deployment speed (and direction) as well as the wind present. Side winds can turn the pack-job as it gets to line stretch, while front wind usually has little effect on turning the canopy before inflation. If possible (distance to the wall is big) turn into the wind, else call off the jump if side winds exceed what you are comfortable with.
Line twists are the result of the canopy turning during the opening process, loading the canopy single sided and a combination thereof:
If you find yourself in line twists and are lucky enough that they are in front of your face (as opposed to behind your head) don´t delay or start kicking like a skydiving b!“§$%ch. Reach above the twist if necessary climbing up your own lines. This may be hard, but you´ll be amazed at your super human power when your life depends on it. Make the canopy turn if you´re headed toward the wall: preferably by pulling on lines or riser links of the rear riser as you will turn and slow things down at the same time. Front riser or lines of the nose will also turn the canopy but accelerate and increase the turn radius. Once on heading to clear air you can take your time and unwind. (no pun intended)
Cliffs of a height more than 300 meters (1,000 feet) warrant assuming a tracking position to increase the distance to the wall before deployment. While a 300 meter cliff only allows for subterminal tracking it is still a good idea to use the 4 or so seconds to squeeze 10 or 20 meters out of the total distance away from the wall. A higher cliff warrants tracking as long as you can to gain the maximum distance, though your forward speed will be much higher at deployment. This in effect will put you're deploying canopy behind you as you fall away on a forward angle from the decelerating parachute. As your risers load they will still be well behind your head at a +-45° angle. If your body position is not completely square to load the risers simultaneously, you may just find yourself in line twists that still spool up as you wonder why this happened.
This may be hard, but you´ll be amazed at your super human power when your life depends on it
Fact is: the side of the canopy on which the riser loads first starts to fly first i.e. right riser loaded right side canopy inflates and flies forward hence causing an off heading to the left. Since the riser on the right pulled on your right shoulder, you in turn will spin to the right and find yourself with line twists behind your head not knowing in which direction you are flying. Nevertheless, if the canopy opens hard and your body is flung with energy you may actually turn to the left and spool up into line twists left. There are other factors such as the recoil action of your dacron lines, etc, but let's not add unnecessary variables.
With all the antlers of rigid camera gear and extended arms to hold them in place a line twist can make it virtually impossible to move your head to see whats going on. It would take time you don´t have to determine the direction in which the canopy is flying. The scary part here is that you need to make the canopy turn if it is aiming at the wall. You can do this by reaching up as high as possible and grab a riser or lines to pull the canopy into an asymmetric state that will make it turn. However, if you were flying away from the cliff you may actually be turning it into the the cliff if you don´t know what's going on. So,- quickly determine if you are in danger and make the canopy turn if necessary.
To reduce your chance of line twists behind your head be sure to assume a head high, arched position before deployment.
Don´t pull too high, and definitely not too low
Don´t pull too high, and definitely not too low:
Some people may argue that a higher deployment is safer, but think again:
Not making use of the available altitude = less tracking distance from the wall and upon a severe off heading opening, 180 or line twists, you may hit the wall quite a way up from the talus only to be rewarded with a number of bounces all the way down to come to rest at the bottom. That is, if you don´t hang up somewhere in between. I consider a reasonable deployment altitude about 150-200 meters AGL for trackers and a bit higher for wing-suit flyers though this may vary depending on the terrain.
Your input is welcomed and I wish you consistently on-heading openings on your future jumps!