20th August, 2003

This Wednesday looked promising in forecast, so I booked FVV with the intention of attempting the Bury St. Edmunds - Shipston-on-Stour triangle. However, by the time daily checks had been done a thin shelf of cloud at the top of the inversion had appeared to the north-east and cumulus had started to pop. This showed that the shelf was very thin because the first cumulus were sticking up through it: you could see a diffuse reflection from sunlight on the cloud tops through the thin layer. This must have made an amazing cloudscape from above. Shortly there was a lot of spread-out to the north and east. The club pundits were unanimous that going north or due west was a bad idea and then split into those who thought the thing to do was to go and play in East Anglia and the rest who thought that it was best to go south-west first and then into East Anglia as conditions there would improve in the afternoon. As my mentor was in the second group I was persuaded to declare Didcot and Downham Market:

Task map

This turned out to be a most enjoyable flight despite slightly more difficult navigation. From Old Warden as far as Aylesbury the outward track skirts along the edge of the London and Luton control zones as far as Ampthill and then passes under the Luton CTA until Leighton Buzzard. Finally, there's a corner of the Luton CTA over Aylesbury, so attention is needed to avoid straying south of your track if you're above 3500 ft. Finally, you'd best not be south of your track as you approach Didcot because that will put you in the Chalgrove parachute dropping zone and you really don't want to go there.

I took a winch launch at 10:28 and it was immediately apparent that there was good lift around under a 4300 foot cloud base. I made a start 8 minutes later. The day was very nice and clear, with a light westerly though it was hazy at flying height.

I started by going south west to Didcot. That turn point is a power station south of Oxford. It is huge and stands out on the flat Oxfordshire countryside like a cardboard model on a painted table. You can't miss seeing it from 25 km away given reasonable visibility. The run to Didcot was under high cumulus. There was a lot of spread-out, but plenty of lift under it organised into a series of short but nice cloud streets. The route took me smack over Woburn Abbey and past Bletchley Park. Woburn Abbey is the the Duke of Bedford's place and site of the UK's oldest Safari Park. You drive your own car round roads in the animal enclosures, hoping the baboons won't steal your windscreen wipers. As I flew over at 3500 I could see lines of cars in the animal enclosures and even the herds of animals the occupants were watching. I was south of track as I passed over the M40: you can see the detour I made to the north to avoid the Chalgrove DZ and to keep clear of RAF Benson. Things got slightly more difficult as I arrived at Didcot and flew out from the overcast into blue conditions. I had a sticky moment, and the lowest point in the flight, when I got down to 1600 ft over the last village before Didcot before finding lift under a small cumulus and then riding the plume from the power station up to and round the main chimney, the actual turning point, and then moving off to a nearby cumulus and so back onto a nice cloud street heading east. I had company under the cumulus as another glider came round the turn point while I was topping up on height before heading for the cloud street.

The return run was similar except that there was top cover above the cumulus layer. The northern edge of it ran almost exactly along my track. For a while there were useful streets under it but after Aylesbury these got scrappy, so I moved out to the north and used the sunlit cloud streets which were working better. This continued until just short of Bedford, where things quite suddenly turned blue. The streets disappeared and were replaced by widely spaced small cumulus caps, which marked some pretty good lift. There had been lots of company between Didcot and Bedford with gaggles in the better thermals and a real need to keep a good lookout for gliders coming the other way down the cloud streets.

After Bedford I set out toward Sandy, moving from one tiny cumulus to the next. About this time I caught up with a V-tailed glider, either an SHK or a Standard Austria. I went for a cloud to the north of its target and was fortunate to find a nice energy line which got me to my cloud with little height loss: meanwhile I could see the other glider sinking steadily until it contacted lift under its target cloud. From here I picked my way from cloud to cloud past Gransden Lodge and out to Earith, heading for Downham Market. Past Earith the cumulus reduced to haze caps and then to nothing beyond Ely and the thermal strength was steadily reducing. I was a good 6 km from Ely because I was following the fen drainage system from Earith to Downham Market, but the cathedral stood out like a model on a painted map under the, by now, blue sky with its tracery of cirrus. I didn't fancy landing out so I turned for home here, picked my way carefully back toward Earith. Just before I got there I took a final climb and calculated I was within gliding range of home, so started the 25 km final glide from there at 4900 ft, arriving at 2300 ft over the field. I was evidently being over-cautious because I then had the problem of shedding 1400 feet in order to join the circuit and land.

The following trace shows the route I flew, while the satellite picture shows the huge area of blue, cloudless conditions covering much of East Anglia and as far west as Bedford at 14:30. Judging from this image there have been sea air incursions from the Wash and along the Thames estuary, apparently without the usual convergence lines but with a narrow strip of cumulus running from south of Bedford past Cambridge to the patch of cloud on the coast near Norwich. I seems like a safe bet that if I'd pushed on to Downham Market, deep in the cloud-free zone, that I'd have landed out nearby.

GPS trace Weather satellite

Time Declared Leg (km) Flown Leg (km)
Takeoff 11:28 GRL
Start 11:36 GRL GRL
Turn point 1 13:16 DID 100.76 DID 100.76
Turn point 2 14:58 DOW 155.68 EAR 120.51
End 15:41 GRL 56.58 GRL 21.22
Landed 15:42 GRL
Distance 313.02 242.49
Time 4:05
Avg. speed 59.8 kph