Flying to Florida, I find myself looking out of the window with more interest than usual. Not that at 39,000 feet I am likely to get much clue as to what it is like to jump out of a plane from around 13,500 feet, which is what I'll be doing in a few days' time. Friday the 13th, to be precise.
Before attempting my first skydive, though, I've decided to attempt to pick up some pointers on technique by trying the simulated skydiving experience offered by Sky Venture, a vertical wind tunnel in Orlando. The idea is simple: dress paying customers in boilersuits and helmets, then blast them upwards with a 120mph column of air inside a Perspex octagon, thus simulating freefall.
Sky Venture looms over the Wet 'n' Wild waterpark like a giant food blender. In the reception area, photo-graphs on the wall depict various personalities skydiving for real, including a grinning George Bush Snr, presumably surrounded by Secret Service agents ready to form a human cushion below him in the event of parachute failure.
The normal tourist experience is two minutes in the wind tunnel, although experienced skydivers can book 10-minute slots for what looks like a glorified fairground attraction. But Laura on reception explains firmly: "It's a sport, not a ride."
Our instructor, Greg, gets us kitted out and advises on "arching", the standard skydiving position. With arms and legs spreadeagled, the idea is to raise your head, thrust your pelvis downward and thus arch your back. But it soon becomes clear that I'm going to need extra tuition; my first stint in the tunnel is chaos. I bump the walls before flying across the chamber to try to headbutt the controller behind the glass.
I finish by descending inexplicably to lie like a clumsy fish on the mesh floor. My second attempt is better, however, as I finally begin to establish some stability, and my final effort is a positive revelation: I manage to stay completely still, gently rotating in midair.
Sky Venture attracts skydivers from around the world and, as I leave, the Russian national team are busy practising their routines . They don't touch the walls once as they change formation in a series of crisp, well-choreographed moves.
On the fateful Friday I transfer to the manicured surroundings of Saddlebrook Resort, near Tampa. It is just down the road from the Zephyr Hills drop zone, established in 1990, open year-round and reputed to be the best in Florida. It is early morning, and the only sign of life at Zephyr Hills is a cat sitting by the office door. On a noticeboard is a cutting from the Daily Telegraph reporting the inquest into the death of the UK skydiver Stephen Hilder, who fell 13,000ft in 2003.
Someone has highlighted one line: "The inquest, in Scunthorpe, also painted a stark picture of the skydiving culture, which included drinking, drug-taking and sexual promiscuity." Things seem somewhat staider in Florida: another cutting refers to a local grandmother of 82 who made her first skydive recently.
Igor, my AFF (Accelerated Freefall) instructor pitches up. He is a big, dark-haired Russian, living aptly enough in St Petersburg, Florida, who saw action in Afghanistan with the Soviet Air Force before notching up 4,000 jumps since 1986.
My original plan had been to do just a tandem jump, harnessed to a qualified instructor, but Igor is more than a little insistent that I complete the six hours of classroom instruction required to reach AFF Levels One and Two. At this formative stage in my skydiving career, the ultimate objective is to execute a solo jump with two instructors holding on to me. We agree that if the tandem is successful, and I'm still alive afterwards, a solo jump will follow.
One classmate, Jason, is a farrier from nearby Citrus County who recently tried his first tandem. "As soon as I hit the ground I was ready to do this [solo] course," he drawls. His T-shirt reads: "My mommy says I am special". Another student, Scarlett, who is training to join the CIA, has notched up seven tandems.
"The number one thing is to open your parachute on time. It's a pass/fail course," explains Igor. "And it's normal to be scared. If you weren't, we would be asking questions."
Igor has, he tells me, experienced just the two parachute malfunctions, including one with a poor soul making his first tandem jump. "Be aggressive and positive," he suggests. "And never give up [if you have problems], because the alternatives are worse."
We rehearse the midair drills, lying on "creepers" (trolleys on wheels), and repeatedly practise arching, pulling the ripcord, cutting away the main para-chute and deploying the reserve. We also study the construction of a parachute, identifying the brake lines, which will help reduce our forward speed, and the various bits of the harness.
As we tuck into a lunch-time sandwich, a gaggle of skydivers land with a rush of colourful canopies, some dragging their feet expertly in the swoop pond, a purpose-built, shallow stretch of water on which parachutists can "surf" on landing. Then the Tannoy announces: "Load two, 20 minutes", and a group of US Special Forces troops wander out, decked in black.
Next, we get some advice on steering our parachutes. Each year, around 30 skydivers die worldwide, around 90 per cent perishing because they make mistakes under an open, fully functional parachute, such as hook turns, when a parachutist corners too steeply too close to the ground.
"But," says Igor with a grin, "if you are conservative you will be jumping a long time, usually until you get married and your wife doesn't want you to jump any more. Skydiving usually wins."
It is late afternoon by the time we get suited up and walk nervously out to our plane, a DeHavilland Twin Otter, an aircraft renowned for its capacity to climb rapidly, at about 1,600ft a minute.
As we climb, someone rolls open the door at the back to let in some air, which I badly need, and the solo skydivers start tumbling out, looking up at us as they begin their descent to Earth.
I am feeling healthily scared. "This is seriously crazy," I think. Igor's dark eyes have a faraway look; possibly he is anticipating the large dose of adrenalin I imagine will be arriving shortly. As we stand by the open doorway, gazing down at patches of green Florida through scattered clouds, it all feels utterly surreal. We rock forward, we rock back, and then take one of the biggest leaps possible.
The first two seconds, no matter what people tell you, are scary. Very scary. Your stomach lurches, while your overstimulated brain is yelling: "Get back on the plane!" But the only way out of this is down. As I assume the arch, Igor throws a small drogue parachute to slow our descent; 120mph is the maximum speed at which human beings fall, a speed known worryingly as terminal velocity.
It is, without doubt, the maddest of minutes, like floating in a bright, roaring gale. Then, just for kicks, Igor puts us into a series of dizzying spins. My endorphin-flooded brain struggles desperately to establish a point of reference; a wind tunnel this isn't.
At 4,000ft, Igor lets me pull the ripcord. The jerk isn't anywhere near as severe as I'd been expecting, and with the canopy open we circle down. As the drop zone increases in size, we make a short detour upwind and literally step back on to terra firma.
The evening passes in a euphoric fog, and I head home a changed person. Unfortunately, it is the same person who spends the night fretting about the various calamities that lie in store the next day, all of which involve approaching the ground at speed.
Igor's sales pitch had bordered on the pushy and, thoroughly unnerved, I phone the drop zone at 6am to cancel, knowing I may well live to regret it my decision. An expert massage at the Saddlebrook Spa helps ease my pain the next day. If nothing else, I still get a buzz when I imagine being back at that metal doorway at 13,500ft.
Ways to drop in on Florida
Marcus Waring (above) travelled with British Airways Holidays (0870 243 3406, ba.com/holidays). Seven-night fly-drives to Tampa or Orlando from £521, including car hire and flights. He stayed at the Crowne Plaza Universal (001 407 781 2107, ichotelsgroup.com) in Orlando and the Saddlebrook Resort (001 813 973 1111, saddlebrookresort. com) near Tampa. Sky Venture (001 407 903 1150, skyventure.com) offer two one-minute wind tunnel rides for £22. Skydiving at Zephyr Hills can be arranged through Skydive City (001 813 783 9399, skydivecity.com). Prices from £102 per person, which includes pre-jump training, equipment and a tandem skydive. For more information about holidays in Florida: 0870 770 1177, visitflorida.com