'Still smiling?' asks my instructor, Adrian, as our two-seater glider ploughs a furrow in the earth and crunches to a halt in the middle of a field. Technically, it is a perfect landing, but to me - accustomed to the charter-flight luxury of Tarmac, a jet engine and soft rubber tyres - Adrian's touchdown at the London Gliding Club near Dunstable, in Bedfordshire, has all the elegance of crashing a sledge at high speed.
That's the problem with gliding: it is so far removed from the average person's experience of flying, it seems totally mad and counter-intuitive. No wonder not many people try it. First, there is the paradox of being airborne without power, a concept even more baffling than a 747 staying in the air. These carbon-fibre albatrosses with their giant wingspans can travel 500 miles, remain aloft for hours and hurtle along at 100mph or more. How do they do it? Then there is the absence of an airstrip: you take off from a field full of rabbits and skylarks, then, if your flight goes pear-shaped, land just about anywhere you like. The day before my course, a pilot came down in a field of oilseed rape - as the yellow stains on his trainers proved.
In the cockpit with Adrian Hobbs, I learn about other manoeuvres that defy logic. If the glider 'stalls' and goes into a spin, you point its nose towards the ground rather than up into the air, as self-preservation dictates. Once it stops spinning, you gently pull out of the dive. To 'bank' left, you push the joystick to the left - which is logical enough. Then, when you return the stick to its central position, absolutely nothing happens.
The plane continues to turn in a graceful circle until you push the lever way over to the right. Teenagers weaned on Nintendo don't have a problem with this, apparently, while anyone who has steered a yacht or a car does. If you can get your head around 'driving' in three dimensions and the mystery of being airborne at all, gliding isn't as terrifying as it seems. In fact, it is marketed as a safe sport for everyone from 12-year-olds to pensioners. 'If you can manage a walk in the country,' says the London Gliding Club's brochure, 'you should have no problem.' (You also have to be mobile enough to fold yourself into a cramped cockpit, and tall enough to reach the controls.) As part of its training initiative, the club runs holiday courses suitable for families at its centre on Dunstable Downs, ranging from a single trial flight (£35) to a five-day programme (from £349). The longer courses are residential, using bed and breakfast places, caravans or bunkhouses at the club (£30). Many students go solo after between eight and 12 hours of accompanied flying.
The course I am on is Flight 2000 Plus, featuring a safety lesson, two launches and an hour or so in the air 'some of it at the controls, but mostly as a passenger. Unnervingly, it includes a briefing about parachutes. At first, I think Adrian is joking when he passes me the blue backpack and tells me to strap it on. As he talks me through the ejection procedure, showing me the lever that jettisons the cockpit canopy, sweat forms icicles in my armpits. 'To release the chute,' he says, 'pull the red pin. Don't feel for it, but look. You'll probably be falling upside-down.' I laugh nervously, and Adrian grins. 'It's time for your first aero launch,' he says.
An aero launch is where the glider is hitched to a conventional powered plane (or 'tug') and towed into the air - in our case, to about 2,500ft, which is where the clouds begin. 'We never fly in cloud,' says Adrian, 'because it's too disorientating.'
After a safety check, the plane drags us like a toboggan across the grass, and within seconds we are airborne. So far, it's like taking off in a normal plane, but then there is an ominous 'ping'. As Adrian releases the towing cable, the engine noise of the 'tug' fades and the buffeting from its propellers stops. We are silently, miraculously airborne, swooping along at terrific speed like a giant bird.
The reason why gliders travel at such speed is gravity; they are, if you like, 'falling' at a very shallow angle, determined by the aircraft's aerodynamic design. For every foot of vertical drop, the glider travels dozens of feet forwards, and the pilot's job is to find an air current that will take it higher again. The best-known currents are 'thermals', formed where warm air rises off the earth and often marked by cumulus clouds. By reading cloud patterns, the pilot learns to judge where the best thermals are - and circles in them, slowly gaining height. Wind deflected by hills also provides uplift, as do the 'waves' of turbulent air caused by more distant mountains, allowing gliders to travel hundreds of miles cross-country without having to land.
'There is tremendous energy up there,' says John Jeffries, the club's veteran flyer and instructor, who has been gliding since 1949. 'Think of all the people in the world scrabbling around for oil,' he says, 'when there's all this untapped energy in the sky, thousands and thousands of horsepower. A cloud contains two or three tons of water, all held up by nature's forces. That's what we're harnessing when we glide.' As we take off a second time - this time dragged into the air by a cable attached to a high-speed winch - the forces of nature are all too apparent. In a winch launch, the glider lurches violently across the airfield then ascends with an angle of trajectory more like a rocket, exerting a noticeable G-force. As the cable is released again, we soar free, then stabilise for a minute or two.
'You have control,' Adrian announces, which means I am flying the plane alone. Cautiously, I execute a left turn, then a right turn, keeping the nose pointing slightly upwards so we don't lose precious height. The joystick is finely tuned and sensitive and I can feel turbulence through the controls as we enter a thermal.
As my confidence builds, Adrian takes control and shows me what the plane can really do. First, he cranks it round in tight circles, gaining 200ft with a little help from the Downs. 'This is a wingover,' he says, dropping the left wing suddenly and pirouetting in a tight turn. My stomach clenches and I feel I will be thrown through the Perspex canopy. It is scarier and more exhilarating than any fairground ride. Traffic grind along the M1 below, the mansions, swimming pools and riding stables of millionaires appear like Ken and Barbie toys. It may be crazy, but gliding gives you a true perspective and a sublime detachment from life's banalities. A week later, I still haven't come back down to earth.
• For details of London Gliding Club courses, call 01582 663419.
Cleared for take-off
Booker Gliding Club: Wickham Air Park, Marlow, Buckinghamshire SL7 3DP. Tel: 01494 442501
Lasham Gliding Society: Lasham Airfield, Alton, Hampshire GU34 5SS. Tel: 01256 381322
Cambridge Gliding Club: Gransden Lodge Airfield, Longstowe Road, Little Gransden, Sandy, Bedfordshire SG19 3EB. Tel: 01767 677077
Midland Gliding Club: Long Mynd, Church Stretton, Shropshire SY6 6TA. Tel: 01588 650206
The Scottish Gliding Centre: Port Moak Airfield,Scotlandwell by Kinross, Kinrossshire KY13 9JJ. Tel: 01592 840243
Strathclyde Gliding Club: Lethame Road, Strathaven, Lanarkshire ML10 6RW. Tel: 01357 520235
