Article published in Volume Three No. 3 '' issue.

Copyright fotoglider/Paraglider Magazine 2004

                        Ooops!           Did you arrive rather than land?                                       

Film strip from the helmet camera show the progressive addition of rear riser flare while avoiding the stall point.

The Down wind or up-slope landing…

 Part of my regular flying ‘tool kit’ is the controlled (ending both upright, on my feet and where I was aiming for) ‘down wind’ or ‘up slope’ landing or even both together! 

So the first question must be…

  WHY would a pilot WANT to be able to land this way?

 Reading numerous PG accidents reports we see, as commonly stated in aviation, that

 “there are no new accidents only new pilots having the same old accidents”

  In general aviation accidents often split into those on the flat bits at/near an airfield and CFIT (controlled flight into terrain) usually while on route when a pilot fly’s a perfectly serviceable aircraft into the ground, normally as it rises to meet the aircrafts flight path!

Still frames above taken from video, the wind is blowing up the ridge seen in the images and after take off from the top I have turned almost 180* to land on the up-slope with a tail wind. A wind sock is set at the top of the slope and can be just made out near the right 1/3 of the frame.

  So in the freeflight world what do we see?

And more importantly what can we do about it?

  The first ‘obvious’ answer is the case of LZ ‘airfield’ accidents, these mainly fall into the ‘down wind’ category  of this article… mmm those who listen to the ‘Paraglider Radio’ show will know I distrust the ‘obvious’ in aviation. What often occurs is the pilot realizes at the last few moments that they have a tail wind before touch down (by the end of the article you should hopefully understand this can be a non-event J) and instead of a minor ‘slide in to base’ [mh1] they spin/stall or fly into an obstacle as they try to turn into wind.

  If you fly in the normal range of wind conditions, adding your airspeed to the tailwind (which most of the time can’t be too high or you would have spotted it earlier/higher) and you end up looking at your ‘slide into base’ at the sort of speed that as kids we fell off our bikes, except now we are kitted up with padded harnesses/gloves/full face helmets etc!

 The greater damage to the adult pilot’s body is not that as youngsters we had a higher ‘bounce factor’ but the mind set of ‘flying’. On, or should I say coming off, our bike we didn’t try to turn ‘into wind’ and end up with a high vertical impact (stall), instead we tried to aim to avoid anything sticking up from the ground, so why do pilots insist on trying to do a 180? By ‘fixating’ on turning into wind you ending up splat, face first into a tree/wall/parked car etc or just plain stalling into the ground below you!

  How has our pilot ended up with a tailwind near the ground? Well the list runs from human error, which can be as simple as not paying attention to changing conditions, on to the ‘backdraft’ effect of a big strong thermal popping off up wind of the wind sock leaving it showing a false ‘prevailing wind’ at the time you looked at it! When you add in the fact that much of our flying can be away from flat clear and open airfields, it is easy to imagine (or remember) lots of situations where ‘arrival’ would normally be a better word to use than ‘landing’ listing all the situations would fill the magazine let alone this page!  

As one example, try imagining bottom landing where the valley side is ridge soarable and you expose your self to a number of causes of unexpected landing winds including katabatic flow from the head of the valley and along the valley floor at right angles to your ridge etc.

 OK Incidents happen…. This does not mean an accident must follow

Ok so at some point most pilots will face a situation where landing, while gliding downwards, instead of converging gently with a flat field you meet ‘hard stuff’ that seems to jump up towards you!

‘Honest that hill was not in front of me as I approached to land’

 Take even a 6:1 glide angle as your brain ‘makes’ you pull brakes, slowing your normally 9:1 modern glider, just add in a fairly gentle 20* upslope and you end up facing a 30* or worse ‘arrival’, you ‘know’ that will hurt… so you slow down more… Encounter (for what ever reason) a tail wind before touch down and we can be talking major hospital time L

 So what does it take to make these ‘arrivals’ into ‘landings’?

 Well if you could slow down your ground speed AND at the same time reduce OR better still; negate your sink rate, you would be well on your way to a solution.

  The obvious (mmm!) thing to do is exactly what you brain tell you to do, that’s pull on lots of brake… Instead do some re-thinking, using brakes adds mostly parasitic drag ‘deforming’ the trailing edge, this gives the wing two sets of 'adverse yaw' as left and right brake both produce more drag than lift.

Fig. 1 Blue lines show a normal landing flare where the brake lines on both sides pull down the trailing edge increasing the drag, and quickly the sink rate!

There has been a lot of critical comments on some internet news groups consisting of personal attacks, directed at me, for using the term Adverse Yaw, first I would point out until I started to mention that there are TWO ways of yawing a wing IN THE SAME DIRECTION no one else 'specified' the types of yaw we get in paragliding.

One 'yaw' is by a secondary effect of roll, this DOES NOT involve any significant increase in drag, while the 'normal' method of producing a change in the yaw axis IS BY PRODUCING FAR MORE DRAG THAN ANY ADDITIONAL LIFT (see 'min sink') BY APPLICATION OF ONE BRAKE.

My development of the use of a specified term to differentiate 'types' of yaw was from a starting point of 'min sink' where pilots are normally taught that adding brake is good yet all in aviation surely regard more drag as something bad, even if it is often used to a useful purpose i.e. flaps on landing!

PS the term 'proverse yaw' which I have been 'told' to use is not even a word in the dictionary and makes no sense if used to talk about something which involves giving an aircraft MORE DRAG!

 Back to the article!

If we could tip the whole wing to a positive pitch (gliders and engine ‘out’ powered planes need a negative pitch to glide), just like a GA C152 has during a landing as the pilot eases the yoke back to the ‘hold off’ remaining just above the runway while ‘burning’ airspeed, or like a hang glider on landing flare.

  Translating this to paragliding, by keeping our airspeed high and acquiring the rear risers while still say 10ft above the ground, start to ease them down instead of using the brakes at about a foot above the ground this will produce mainly another type of drag, that is lift induced drag.

Fig. 2 The zig/zag in the (yellow) C risers represent the shortening as the pilot eases them down.

  Produce lift at the same rate as your normal sink rate and what happens is you ‘float’ in exactly the same manner as the ‘hold off’, prior to touch down used in GA landings. Take this a step further and by making progressively more lift than your normal sink rate and you climb! That sounds perfect for the upslope landing as long as you leave it to just prior to touch down, but wait a minute where do we get all this ‘engine’ power from enabling us to climb and how do I control it? Instead of limiting our thinking to brakes, weight shift and speed system etc. we need to start to look at all our choices/controls/options.

  ‘Fuel’ in paragliding

   We do have in a limited fashion ‘fuel’, it is our mass with its store of kinetic energy (given by your airspeed) as well as potential energy (from your altitude) by using the ‘opposite’ of the speed system, that is a ‘rear riser flare’ to slow down then just like a HG doing a dead stick/fly on the wall landing, we keeping a very ‘clean’ aerofoil with no ‘draggy’ deformation of the trailing edge, can gain a small amount of height…. And wait a minute, thrown in for free we ‘burn’ of air speed to just about zero. Leaving just a few quick steps to take care of the remaining ground speed produced from the tail wind.

 Having come this far why not go for some ‘style points’?

 With your feet safely on the ground and getting rid of the remaining (tail wind) rate of travel, why not spin the wing to get it to drop down wind and in front of you in a neat wall! All you need do is add more rear riser on one side and reduce it on the other side as it passes over head and instead of a messy tangle wrapped around you, with practice when up slope/top landing you end up ready for your next pull up and take off back the way you came from i.e. into wind!

  The final question remains, if what we hope to avoid is having our name in a accident report, will, like the occasions when a practice ‘engine out after t/o’ in GA training turns into REAL incident can we learn/practice a rear riser landing without it becoming an ‘arrival’?

 Practice ‘safe practice’

  Safe is simple, just practice ‘rear riser flares’ into wind and on a flat LZ to start with! Once you get the basic landing sorted 100% without any ‘zoom climb’ and always nail the ‘dead stop stall’ landing then start doing them up slight inclines which are into wind, working up to steeper slopes a step at a time, or in the same manner practice first with some x-wind and move on to a 1kt cross tail wind and finally work it up to a level of tail wind you are happy with.

 Remember we are training to easily survive something most hope never to encounter, this in my opinion is something it is well to apply to all your training, practice for the thing you hope never to need and your flying should be fun and stress free.

  Flying my DHV2/3 Vertex G-BZVI we have one SE sea breeze flying site with a low grass ridge above a flat grass park, where in a fresh East/NE wind I regularly practice landing with a 10kt tailwind!

 While we do not aim to encourage pilots to take training to any where near this level, by avoiding all the problems of just using brakes and having a slow, safe and step by step training approach it shows what could be done to cut accident rates associated with at least one type of incident.

    Extra photographs captured from the helmet camera and video footage should be online soon