One day we were below 2000 feet and still two or three miles from the airfield, so we decided to head straight back for a left-hand circuit and landing.
| Just in case there was any available ridge lift still to exploit, we lined up the downwind leg to take us close to the ridge south of the airfield. We could always take the lift and abandon the approach. Then there was a call on the radio: the wind had changed direction while we were airborne and we now had to land at the opposite end of the runway. So we were now in the wrong position in the reversed circuit. I was not sure at first how to get us back into the correct position for this modified approach - but the instructor pointed out that all it took was a swift 180 degree turn into a right hand circuit instead of the original left hand circuit. | |
As we were now established in the downwind leg, it was time for the downwind checks. I changed our pitch to gain an approach speed of 55 knots and re-trimmed to maintain the glider attitude. As we passed the landing reference point away off to our right, I turned us 45 degrees right into the diagonal leg, then after a couple of hundred yards, right again through another 45 degrees onto the base leg and the runway started lining up nicely on our right.
On another occasion I was flying over the radio mast on the hilltop south of the airfield circling to the left in a weak thermal. Like many pilots I was finding turning left easier than turning right. Apparently it's because right-handed people push move their hand across their body to turn left, which is easier than pulling their arm out further to the right when turning right.
It was odd to see the hilltop only a couple of hundred feet below while in a steep bank with an indicated altitude of more than a thousand feet. As our height was approaching the circuit decision height (i.e. when you decide whether to take any available lift or head back for a circuit and landing), the instructor suggested we should move towards the airfield. With the wind still from the SE, I decided on a left-hand circuit from the south and headed over to the high-key area at the start of the downwind leg.
Then the instructor said he'd demonstrate a zig-zag circuit. After establishing us in the high key area, he turned us to the right, 45 degrees away from the airfield. He asked me to shout when I thought we were too far away. I mentioned that the hilltop near this north east end of the airfield now seemed awfully close below, so perhaps we should now turn around - but he pointed out that it was only a bit close if we were planning to land on it (!) We could in fact just fly past and around the peak and we'd still not be too far out from the ideal downwind leg. As we drew alongside I duly shouted that we were too far away and he turned us back pointing 45 degrees towards the airfield. This time shouted when we were too close to the airfield. When I called out he said I was a little late as we were almost over the airfield perimeter. After another couple of zig-zags and my shouts at appropriate extremities of the zig or zag, the instructor settled us back onto the end of the downwind leg at the low key point turned onto the diagonal leg.
He concluded that I was still estimating the ideal downwind position to be a little too close to the airfield. No surprise, based upon previous feedback. Clearly I was a bit shy of getting too far from the safety of the airfield, but I'd have to move further out to make the approach easier in future. As it turned out this was easier said than done.
The first time I flew in a strong wind, I had to anticipate the effect of the headwind on the approach & landing and set a much higher circuit speed. A rule of thumb says you should add a third of the anticipated windspeed to the normal approach speed of 55 knots. With the windspeed gusting to 25-30 knots I set and trimmed for an airspeed of 65 knots. I also chose the circuit high key area to be higher than usual (1000 feet rather than the usual 800 feet) and closer-in than normal to allow for the effects of turbulence and sink in the circuit.
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On the downwind leg the tailwind pushed us very rapidly along the desired path. The groundspeed was probably approaching 100 knots. There was a temptation to slow down due to the effect of the ground whizzing past, but it is airspeed that counts, so you must constantly monitor and maintain a safe airspeed during the circuit. With the anticipated strong headwind on landing I selected a reference point point about half-way down the runway. As I came abreast the reference point I had to turn very promptly onto the diagonal leg. The idea was to keep us close to the airfield at all times, reducing the risk of being blown back too far which could result in an undershoot short of the runway. On the base leg there was a real sense of "flying sideways" as I had to nose into wind to maintain the desired rack. Turning onto the approach, much closer-in than usual (only a little short of the runway threshold), the glider seemed to stop in the air as the strong headwind took a grip. There was a temptation to open the airbrakes 'as usual' - but I was reminded to be sure that we would overshoot without airbrakes before I opened them - gently with caution. As we descended I was also reminded that on a windy day you also have to be wary of any wind gradient - or a tendency to balloon during the round-out due to the excessive airspeed. |
On another occasion I realised I was too low on the approach and promptly had to shut the airbrakes for a few seconds to reduce our rate of sink and glide back onto the correct glideslope.
Coming home one windy day I was flying along the downwind leg when we encountered rapid ridge lift due to the wind blowing up the hillside below. I had to fully open the airbrakes quickly to keep us down on the correct glideslope.
I was learning that you have to be prepared to modify the circuit at any time to deal with the circumstances. Experience enables you to predict many eventualities ahead of time, making the whole circuit easier. Always think ahead and plan to make your life easier. There is really no such thing as a standard circuit.