Imagine you're a falcon. You effortlessly ride the airwaves, circling upwards in the thermals, just flicking a wing feather every now and again to change direction. Gliding is a sport which almost fulfils the dream of flying like a bird. There is no distracting engine noise and you have wonderful views of the countryside below. Reading the weather provides a real mental challenge and yes, we sometimes do watch the birds for clues!

The Colditz Cock

Modern day gliders are made from fibreglass rather than the original wood and fabric designs. The older use of such simple materials made possible one of the most ambitious escape plans of the second world war inmates of Colditz prison.

With unbelievable audacity, a glider with a 32 ft wingspan was secretly built in the attic of the castle. Materials were improvised from whatever came to hand eg bed-boards, iron bars from the windows and even the prisoners' own sleeping bags were used to provide the skin of the aircraft. After eight months of work, the glider was finished but never used.

Recently, a replica has been constructed so the surviving members of the Colditz Cock team may yet see their design tested in flight

Do you fall out of the sky when the wind stops?

Keeping a glider airborne is all about finding areas of rising air, known as lift. There are several different types of lift.

Thermals

Thermals are the result of warm air from the earth escaping into the colder skies above. When you see birds circling high above you, they are taking a free lift from a thermal. At the top there will often be a large fluffy white cloud with a flat bottom. Think of a hot Summer's day with blue skies and you're probably picturing the right sort of cloud. If you're anywhere near a gliding airfield, there may well be some large-winged aircraft rising dizzyingly under the clouds.

Ridge Lift

Ridge lift is caused by a long edge of hillside getting in the way of a steady flow of air. When the airstream reaches the hillside, there's nowhere to go but up. We can then fly quite happily above the ridge, supported by all that rising air. The airfield I fly from is lucky enough to launch directly onto a ridge so with a favourable wind we can fly back and forth for hours if we really want to.

Wave

Wave can be King of the skies for providing strong, steady lift. It's easiest to imagine if you consider the analogy of a stone in the middle of a river. As the water flows against the stone, waves of ripples spread out from the obstruction. A similar thing happens to moving air as it hits mountains and hilltops sticking up into the atmosphere. Standing waves occur which can be seen in the sky in the form of lens-shaped clouds, lying still across the direction of the wind instead of moving with it. The stronger the wind, the bigger the waves and the faster they lift lucky glider pilots up, up and away.

So if you're a glider pilot, you'll be watching for signs of these conditions and making the most of them to get you high in the air and keep you there. If there's no wind, you might still find some thermals. If there really is no rising air to be found, then you'll gently glide downwards in a controlled descent. If you've calculated your height, glide angle and distance from airfield correctly, you'll make it back home. If you've miscalculated and are too low, too far from home - then it's time to find a friendly field you can safely land in. Glider pilots on cross-country flights will be constantly scanning the ground for suitable fields in case the weather or their judgement fails.

I am reliably informed that golf courses also make good landing sites.

If you want to know more the British Gliding Association can give you more information and (if you are based in the UK) direct you to a gliding airfield near you where enthusiastic pilots will be happy to take you for a ride.