Those magnificent men...

There are five categories of competitive aerobatics: Beginner, Standard, Intermediate, Advanced and Unlimited. Funny: I always thought the sky was the limit. "At Beginner's level, all you do is something like a loop and a roll," says Nick Wakefield, a display pilot who did his first loop and roll in the Cambridge University Air Squadron. He's on hand at the Aviator Hotel at Sywell, Northampton, to do "whatever needs to be done" to ensure the smooth running of the National Aerobatics Championships.

The winner at Unlimited level becomes British Aerobatic Champion. The competition, the last and most important of a season which runs roughly from March until now, is also used to select the pilots for next year's European Cham- pionships. They take place every two years, alternating with the World Championships.

The Aviator Hotel is one of those square concrete places, painted yellow and surrounded on the roadside by chalet-style rooms reminiscent of the Bates Motel. The restaurant is vaguely Art Deco, with flight memorabilia scattered about. Men in kit chat in groups, backs turned to a glass display case. Inside is a memorial to a Lancaster bomber which crashed nearby. A shelf holds copies of those sepia-tinted studio photos everyone had taken of their sons as an unspoken hedge against never seeing them again: uniformed, grinning, bursting with promise. Lovely boys who could have been dandling grandchildren by now. The propeller is polished, and propped up by the baby grand. It's a jarring reminder of how this sport came about.

Thoughts of death, though, are far from the minds of the competitors, who are on their practice day, running through the routines they hope will bring them another kind of glory tomorrow. The nearest I've come to aerobatics was in one of those big wheels with the revolving cages. The fear of flying upside-down was so intense that it's beyond me to imagine how you could do it and steer at the same time. Typically, though, of those who take part in these adrenaline-heavy sports, no one is prepared to admit any element of fear.

"Loop-the-loops," says Nick, "are very simple when you've progressed beyond them. When you first do them they're very, very difficult. It's a bit like when you first learn to drive. You can keep a straight line, but anything like that is beyond you. And once you've got your licence you've hacked that part of it. Starting aerobatics is a bit like starting all over again. You're learning to fly again and it's all a bit disorientating at first".

Understatement, it seems, is all part of the game. The stresses are actually enormous. Even Nick concedes that. "Physically it's very demanding. You'll be absolutely knackered after you've finished a sequence." The main problem is the G-forces. One G is the weight of gravity. These people regularly subject themselves to eight or nine. It's the corners that are the worst: when you're flying straight up, you are weightless. Upside- down is dodgy as well: when you're hanging by your shoulder straps the blood pools in your head.

It's also got tougher, improvements in equipment having increased the stresses. Mike Riley, chief judge, and a Concorde pilot in his spare time, started flying aerobatically in the early Sixties: he was 17 when he first grabbed a joystick. "It used to be very physical, we thought, 20 or 30 years ago, but the machinery has improved so much that the aeroplanes are now much stronger than the pilots." No one who flies planes uses the short word to describe them. If you respect the machine, you call it an aeroplane. "It used to be that the aeroplanes could break if they were misused. These machines are so strong and manoeuvrable that physically you are very much a weak link. You're pushing your own physical limits in an area in which there is very little knowledge."

Mike has represented the country "three or four times, I can't remember", and was chief judge at the World Championships in 1990. He still teaches and flies for fun, but doesn't compete any more. He's very clear on the thrill of why you do it. "It's the challenge of pure flying. It's purely and simply aeroplane handling skill. Aviation is a relatively new human experience and, though we're not the first generation, we're the first century to be able to pursue this particular sport. One is very much at the cutting edge of a new human experience."

Once you have passed through the hotel, you suddenly realise the point of having it there. French windows lead onto a lawn, and then on to Sywell Airfield. A picket fence stops you from wandering on to the runway, and a sign adorns a stone gatepost: "DANGER BEYOND THIS POINT." It is a perfect spot to slump round a white plastic table and watch the goings- on at the aerodrome.

In front of us is a line of helicopters. People in overalls bustle round them; one is being shifted manually with the help of little yellow wheels clamped to its landing bars. Looking at the mechanics, you would think that this is a world quite heavily infiltrated by women. Not so. Most pilots are men. The handlebar moustaches may have flown off skywards, but testosterone still dominates. Only one woman is flying in the competition, Annabel Wakefield, Nick's wife. "There aren't many women doing it, no," says Mike, "though the best British pilot by far is a woman called Louisa Knapp. She's about 25 and incredibly talented."

In the sky, a tiny black and red insect - you would be hard pushed to park more than three Ford Fiestas in the space they fill - flies a straight line upwards, pauses, slides backwards on its own trajectory, flips over and plunges head-first toward the ground. This, apparently, is called a Tailslide. They have some great shop-talk, these flyboys: they do flick rolls and snap rolls and Lomcevaks (Czech for headache), Cuban Eights (a figure eight flown sideways, so called because the Cubans are always asleep), Avalanches ("a Swiss manoeuvre") and Humpty Bumps.

Planes vary from around $200,000 - Sukois, CAPs and Extras (named after their German designer, Walther Extra) - to pounds 15,000 for a third-hand self- built biplane. Mike walks me round, pointing out their features: he recognises individual planes like a bloodstock expert recognises horses. Four-blade propellors for noise reduction, titanium bodies, carbon fibre wings. Seats are tilted at 45 degrees; pilots fly with their feet in stirrups as though preparing for gynaecological examination. This, apparently, lessens the G-forces.

Thomas Haueter, a Swiss DC-10 pilot, reckons he spends about pounds 12,000 a year on his hobby. Why does he do it? "Sometimes I'm asking myself the same question. Sometimes it can be very frustrating. But it's a great sport. It's a good combination of the physical and mental."

Mental, everyone stresses, is what it's all about. Unlike air-show display flying, which is all about crowd-pleasing, talk here is of precision and geometrical accuracy. It's the difference between dressage and show jumping: the uninitiated may enjoy the jumpers more, but dressage is where the real skill lies. Competitors fly a sequence of manoeuvres and are marked down from a perfect 10 for each. "The psychology of the sport is interesting," says Mike. "The pilots are trying to create perfection and the judges' only interest is in the negative side of it. So the pilot has this feeling that the judges are doing something destructive. In a big competition this can create a sense of conflict. People get rather paranoid."

Fully conversant with this paranoia is Alan Wade, competing in Unlimited for the first time in nine years. He started his career as a flying instructor. "But you do get very bored being a flying instructor. It's like being a driving instructor, only the view out of the window's a bit nicer. And it doesn't pay as much." So he took on that extra challenge of doing it upside-down. He's been doing air shows around Europe - "I had to stop competition flying to earn a living" - and only decided to enter three weeks ago. He's a bit trepidatious about his lack of preparation.

That, though, he doesn't necessarily see as justification for failure. "If you walk around and talk to the pilots, none of them have practised for three months, they only got the aeroplane back yesterday, there's far too much fuel in it and so forth. But when it comes down to it, it's all down to the guy holding the stick. There are no excuses."