Need to know: The mission - Jumping out of a plane with a flimsy bit of nylon for support? And in Peterborough, too? Nicholas Barber must be mad

his week's mission is a toughie. Not only am I going to spend a weekend in Peterborough - a testing feat in itself - I'm also going to learn how to parachute while I'm there. On Saturday, I'll be training at Peterborough Parachute Centre. On Sunday, I'll be jumping out of an aeroplane. And to think, passing my driving test took me 18 months.

Sibsen Airfield, Saturday, 0900 hours. I'm tracksuited and ready for 12 solid hours of gruelling physical punishment administered by a shell-shocked ex-para who makes Windsor Davies look like Melvyn Hayes. It doesn't happen. Yes, we train for a morning and an afternoon, but even I wouldn't call it strenuous, despite the fact that the last time I put this tracksuit on was for school cross-country running.

The day is rounded off with a talk on what to do if things go wrong, which can be summarised in two words: nothing will. Then it's off to the bar to swap sky-diving stories. The folk yarn about the friend of a friend who was pureed by a helicopter's rotor blades elicits the most horrified responses, but my personal favourite is the tale of a parachutist who broke his leg by landing on a sheep. The sheep was unscathed.

Sunday arrives. Just in case we forget to pull our rip-cords - unlikely, I would have thought - we first-timers have a "static-line" system: when we jump from the plane, the 'chute opens automatically. Five of us cram into a tiny Cessna 206 and we climb to 2,000 feet. I'm second in the queue to jump. The first jumper tips herself through the side door of the plane. I expect to see her fluttering backwards into the distance like an autumn leaf, the words "1,000, 2,000, 3,000, check canopy," carried faintly on the breeze. Again, it doesn't happen. I hear her say "wuh-" and she is nothing but a speck, far below.

My turn. I balance in the windy doorway and, imagining that I'm sitting on the edge of a swimming pool, I ease myself into the water. Before I have the chance to wonder why I'm still dry, there is the sort of loud flapping noise that is usually followed by the phrase, "bugger, there goes the tent," and when I look upwards, all I can see is a large expanse of ripstop nylon. It's working! The only trouble is, it's working too well. I'm not moving. I'm floating completely still, in a completely silent world.

Or so it seems. What actually happens is that you descend at a steady speed, with the parachute countering the accelerating pull of gravity, so you don't feel as if you're falling. You hang there blithely enjoying the view. Then, all at once, with 200 feet to go, the earth seems to hurtle towards you at a terrifying speed. The sensation is known as "ground rush" and its effects are predictable: I deftly forget everything I have learnt about the landing procedure and end up in a messy, mildly bruised heap. An undignified touchdown, but a happy one. Even sprawling in a muddy field wearing an unfashionable tracksuit cannot dent the elation of knowing I have joined that elite brotherhood that counts Andy McNabb, Jimi Hendrix, Prince Edward and half-a-dozen Blue Peter presenters among its number