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Rotor!
How to deal with the pilot's worst nightmare - being blown over the back of the mountain.

The day was glorious when you arrived - the sky a gentle blue, the wind clean and soft against your skin, the sun shone goldly on the grass at your feet. You stepped to the edge, and launched your paraglider off into the breathtaking altitude. Presently, you were high above the valley, gliding here and there, watching the other pilots drift forwards of the ridge. Clouds began to cover the sky. You watched pilots tuck their wingtips in and head out into the valley. You wondered what was going on. Then suddenly you saw your shadow, far below. You were trapped! The wind, which had begun so quietly, was howling around you with vicious intent, and you began to drift further and further towards the looming mountain ridge behind.

1. Get away from big obstacles
Fly upwind of any mountain as fast as you can - hands up off the brakes, and check your penetration (positive ground-speed). The glider can be accelerated in smooth air by at least 10% by pushing the speed bar. If your glider lacks a speed bar, simulate one by pulling down on the A and B risers (a very strenuous maneouvre). Some paragliders fly faster with the wingtips tucked in, than with them inflated. This is something to test on your next flight, before you need it.

2. Get down
Wind speed usually increases as you get higher, due to an effect called the wind-gradient. Especially in the face of an approaching cold front, the airflow is extremely laminar - the lower layers of air are retarded due to friction with the ground, but the higher up the air flows in seperate sheets at a progressively increasing speed. Quite often you can escape being blown away by coming down, closer to the ground, where the wind-speed is lower. Use 'big ears' (tucking in the outer A-lines of your canopy to collapse the wingtips underneath). Do not spiral or use a B-line stall. Both of these maneouvres result in zero penetration into the prevailing wind, and you will therefore drift with the wind towards any obstacles positioned downwind of you.

Narrow valley systems (The Alps) present an added twist to the problem. They constrict the air below, which can cause very strong valley-winds. If you are presented with a narrow valley below you, it may be best to try and avoid coming down for as long as possible, until you are near a wider part of the valley.

3. Do both
It is quite safe to tuck the ears first, then to push out on the speedbar as well. This increases your forward speed and increases your rate of descent, and the glider remains very stable. Be careful not to push the speedbar first, and then vigorously tuck the wingtips in. The tucks may become a large nose collapse, because of the low angle of attack.

For the technically minded pilot - Tucking ears increases your angle of attack as your glide angle drops, taking your wing closer to stall angle. Pushing your speedbar decreases your angle of attack, curing a potential problem. The glider also has a far higher wing-loading and resultant cell pressure when the ears are tucked in. There is therefore less danger of having a big nose collapse in turbulence when the ears are tucked than when they are open.

4. Recognising that you're going over
The earlier you can do this, the better your chances of taking action. Analyse your flight path after trying the first three steps. If you are going backwards rather than forwards, and are drifitng back towards the mountains, you need to make a decision early. Tuck BIG 'big ears' (tucking two lines in on either side on a glider with three A-lines aside, for example) and have a look at your flight path. Is there any way in which you can safely slope-land on the windward side of the mountain? This is a risky option, as you will have to collapse your glider in very strong winds if you land anywhere near the compression areas on the mountain. (The wind-speed increases in narrow valleys, near saddles in ridges, and at the crest of the mountain). But it is far better to execute a windy slope-landing in constant airstream than to land in the rotor turbulence behind the mountain.

5. Up, up and away
Make the decision early, don't fight a glider all the way down into the compression on top of the ridge to work out you are not going to make it. The most dangerous area to be in is going backwards through the compression, too high to land, too low to turn and run, getting thrown into the rotor turbulence behind the ridge with no height at all.

Hoo boy! So you really are going to be blown over the back. Think. Air is harmless. Rocks hurt. Get as much height as you can in the situation. As the wind blows over the mountain, it is forced upwards in places. Wherever there is lift, the horizontal component of the wind will be less, so you will have marginally improved forward speed. This means that you can climb in the lift for quite some time, building up as much height as possible.

6. Go for the gap!
You are going to cross over the mountain as soon as you reach the top of the lift band, so maneouvre yourself towards the best-looking jump point. Conical peaks are great when they have large drop-offs on all sides. Any area where there is a 'bite taken out of the ridge-line' will have a venturi effect and increased windspeed. These are good areas to run through, as the airflow is usually more laminar; less prone to roll and cause rotor turbulence.
All too soon though, you will climb to the top of the lift band, and the airflow will revert to being more horizontal. Once this level airflow is re-established, you have to turn and run. There is no use fighting now, we are going over.

7. Air space
Having acquired the most height possible, you now want to increase your ground-clearance. It is quite often a good move to fly at an angle across the wind, away from the peak which you climbed in front of. Thus you avoid the worst of the rotor, and race away with the wind. As the ground falls away beneath you, you have more and more space in which to fight the beast.

8. Run
If the route is clear, run downwind. Initially, the airflow will be level. To get your best glide angle, fly with zero brakes applied. It is more effective to stay as high as possible for as long as possible, while the wind pushes you from behind. You are trying to 'lift your feet up and escape the rotor'! Then you will enter the sinking air, that is the downward flow at the back of the mountain. Try to speed your glider up to counteract the sink, fly off brakes and use the speedbar gently. And pray.

9. Rotor!
You were too low, you couldn't escape his jaws. Most paragliders are designed to stabilise, so be prudent with your brake-input. Let the glider fly, but fly actively - dampen out the wild surges, keep the wing as much above your head as possible. And keep heading downwind. If you are high, it is quite possible that you will experience only a few tumbles in the rotor, then you'll be out and away. So don't throw your reserve yet, give yourself a chance of beating the beast.

10. Touchdown
If at any point during the escape, you find yourself close to the ground, and there is any chance that you will land, turn into wind. A downwind landing into rocks is likely to be deadly. You know your own limits best - remember, it was 'lift up your feet to avoid the rotor', not the rocks! The landing is going to be wildly unpredictable, and may be painful. Hopefully you escape the rotor and glide far away behind the mountain before you need to touch down, completing a large (and exhilirating) cross-country flight.

Get your glider in! Gusts of wind can tear you away down the slope, and seriously injure you, even though your landing was fine. There are various techniques, each suiting a particular weather, pilot and glider combination - the B-line stall, the C-line stall, or inducing a front tuck with the A-lines (which requires good timing in strong wind). All require a bit of practice - find a large field and go and play.

A round of applause Whoa! you made it through, you Crazy Skygod Ragwing Pilot you! Congratulations on completing the TEN TASKS OF TAMING THE TYPHOON, you've got one big story to tell the guys in the pub. I hope that this is the last time you need to go over the back, for this is one game where it is better to score a One than a Ten. Those guys that landed out in the valley earlier on? They were the real winners today.

A note on reserve parachutes : You may have noticed that I have not advocated throwing a reserve. The reserve is your last chance - You know you are going to die, so you throw your reserve. In strong winds, the reserve can do more damage than good. It may prevent a hard landing, although in rotor this is unlikely. But you will be dragged far and fast on the reserve, and slammed into anything on the path. It is extremely difficult to collapse most reserves, being pulled-down apex chutes, with bridles that only split into lines far above your head.
A justification for 'tossing the rag' comes from the pendulum motion you will experience on your paraglider during the battle with the rotor. If your glider has become uncontrollable, you can be tossed into the canopy when it surges forwards. You could also you can be pitched into the ground due to a last-minute surge. In both cases the reserve would remain more or less overhead. Make no mistake, landing under reserve in rotor will be very hard. Considering that the average sink rate under reserve is 5m/s, and that the air is sinking at least as fast again. So in this I make no recommendation - deploying a reserve may do good, it may do harm. You are the pilot, it is your call.

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