Avoiding Blow-back

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John Wolfe
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Avoiding Blow-back

Post by John Wolfe » Fri Sep 19, 2014 9:56 am

Hugh mentioned that he was nearly blown over the back at Apache Maid, and he asked for suggestions. This is a great safety topic, one we should cover in a future meeting, but perhaps we can begin the discussion here.

1. Safety in The Bar?!! Yes, your speed bar is a piece of safety equipment. Before you ever begin ridge soaring, you must ensure that your speed bar is properly installed, is effective, and you have the confidence and ability to use it properly. This includes being able to engage it without being a contortionist, dropping the brakes, or standing on your ear.

2. Have a plan. Before launching into what you hope is a ridge soaring flight, think through your flight plan. This includes periodic penetration checks and what you will do in the event the wind strength increases to the point where your penetration drops into single digits.

3. Execute on that plan. Every few laps, or whenever you notice an increase in the wind strength, turn into the wind and measure your off-bar, trim-speed penetration. If it drops into single-digit land (mph ground speed), it's time to push out away from the hill. Since you're already pointing that way, just relax, fly efficiently, and if necessary, add some speed bar to get away rapidly. As you push away from the hill, you will fall out of the lift band, and once that's done, you will usually be out of danger for being blown over the back. Now you can focus your attention on finding a decent place to land, keeping in mind that you must continue flying efficiently and that lateral motion will come from very slight adjustments in your crab angle, not by making a substantial turn, which could put you back into the lift band.

4. It didn't work! If the wind changes quickly enough, your wing is slow, or you were having too much fun to notice the impending problem, you may find yourself making slow, but steady progress...backwards. This is not a particularly good time to panic. Remain pointed directly into the wind, fly efficiently with as much bar as you can safely apply under the circumstances (taking a monster collapse because the air is turbulent and you're mashing the bar will certainly not improve the situation). This is where the other part of the flight plan comes in. You know, the plan you made before leaving the ground? Before launching you talked with your fellow pilots and decided what you would do in this situation. It varies, a lot, with the terrain, so there is no one right answer. But, in general, the goal is to minimize the violence of the mechanical turbulence through which you are now likely to fly. Sometimes this can be done by crabbing off to one side of the hill. In other cases, it's a matter of turning and running over the lowest, smoothest part of the hill. The point is, you cannot be expected to work this out in the air, while under the stress of the situation. Once you recognize you're going over the back, you need to execute on a plan that was made with a cool head on the ground.

So, about that plan, then. You, as the pilot in command, are responsible for making one. And, if you're new to the site, you should get help from someone who has experience with the site. If you're headed out for a ridge-soaring flight, part of the site introduction really should include a discussion of preferred escape routes. Whenever I take a new pilot to Mustang, I try to use the windshield time on the way down there to talk through my escape plan for that particular site. In any case, if your host doesn't provide this information, then please ask for it.

I'm hoping others will join in and offer their views on this topic. We often take our newest pilots to Mustang, which has a propensity to blow pilots over the back. Apache Maid provides perhaps the most beautiful glass-off in the state but also carries the blow-back risk. So, let's do whatever we can to help all pilots, especially the new ones, be prepared for this risk.

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HughR
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Re: Avoiding Blow-back

Post by HughR » Fri Sep 19, 2014 12:59 pm

Thanks John. I got to far back on the RH side of the hill, turned away and into the wind. Cool, I look down notice I'm not making much forward progress, crap .Not going up anymore. Apply speed bar and eek forward but of course loosing altitude. Got back in front of the hill and up and away. I'm always learning something. Not really a true blow back but if I could not make it around forward I would have egressed to the west and would have had a long hike.

John Wolfe
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Re: Avoiding Blow-back

Post by John Wolfe » Fri Sep 19, 2014 2:06 pm

The inconvenience of a long hike pales in comparison to the danger of a rotor ride. Many trips through strong lee-side turbulence produce reserve tosses. Something to keep in mind if that happens is that unlike your paraglider, most reserves cannot be "disabled", so if you've deployed your reserve in windy conditions, chances are you'll get dragged across the terrain and the attendant rocks, cactus, and trees once you've landed. Again, it's good to have a plan...and a hook knife.

So, Hugh, it sounds like you had an escape plan and thankfully didn't need to employ it. Thanks for raising the topic for discussion.

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azwyatt
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Re: Avoiding Blow-back

Post by azwyatt » Wed Oct 08, 2014 12:29 pm

Chandler Papas (a Phoenix instructor) consistently tells his students that applying bar in order to avoid getting blown over the back is a bad idea. He says he cringes whenever he hears observers on the hill telling a pilot to get on bar when they're going backward just off of launch, because they're essentially telling the pilot, "DESTABILIZE YOUR WING!" Though I understand Chandler's argument, I tend to take the middle ground, as you do, John. I feel that a pilot should make an informed risk:benefit decision about this for each situation. Factors should include height above launch, size and shape of the mountain/range, wind velocity, turbulence, your wing's stability on bar. Though going full-bar is a bad idea, especially with a student, 1/4 bar will likely have little adverse effect on the stability of the wing, and will get you another mph to help get out of the danger zone.

Tanner Patty (Flagstaff instructor) once told me that there are two situations in which you always want to throw your reserve: if you have a mid-air collision, and if you get blown over the back. He likely chose to keep the second part of that statement simple for me because I was a relatively new pilot at the time, but there is some merit to it, especially for newer pilots. Depending on the size and shape of the hill, you might choose to deploy your reserve as soon as you're behind the peak of the mountain or you might choose to run with the wind and get out of the wind shadow as quickly as possible. On a smaller hill with a steeper peak such as Mustang, I would argue that if you're more than 500 feet over you might have a better chance trying to run with the wind to avoid rotor, being ready to deploy the reserve at a moment's notice in case it gets rough. Less altitude than that and you'll probably want to just play it safe and deploy your reserve before it gets nasty, as Tanner suggests.

On a bigger hill with a flatter peak such as Mingus, the chances of running with the wind and making a safe landing on the backside if you have anything less than 2000 feet over launch is nil, so it would be better just to go ahead and deploy your reserve.

On lone hills (with no adjacent mountain range), such as the Craters, the best course of action might be to take a heading downwind and away from the hill. Though the venturi will draw you back toward the rotor on the lee, if you're going downwind you have a good chance of outrunning the draw.

A few years ago Sean Buckner, Brad Chastain and I went to Mustangs. Unbeknownst to Sean, his wing was significantly slower than trim because of line shrinkage. Also unbeknownst to him, he had an equipment malfunction which prevented him from using speedbar. I think his brummel hook broke or something. The wind ramped up after launch and Sean, without use of his speedbar, was starting to get pushed OTB. He made a dash for the venturi between Mustang and the other mountain to the south (Bruce?). He ended up being just fine, landing with a ground speed of about -2 mph between the mountains. The landing was hairy, it took him a while to safely disable the wing, but his high-wind kiting skills prevented him from being dragged. So this option has some viability. But if it had been windy enough that he was getting pushed OTB even with speedbar, he might not have been able to land safely in the venturi. So I suppose the moral of the story is that, when flying a site that is prone to push pilots OTB, it's a good idea to stretch your lines back out once a year or so, and use a more foolproof way to connect your speedbar. Sean now uses d-rings for his speedbar attachment instead of brummel hooks.

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