A few years ago, a friend asked me which single invention separated modern man from our ancestors.

'Penicillin,' I suggested. 'Photography?

Sellotape?'

'No,' he said, 'It's flight! For centuries they dreamed about it, from Icarus to Leonardo. But we can actually do it - and we should! We owe it to their memory to learn to fly!'

It's an extreme position, but then Peter is an extreme pilot - he owns three aeroplanes. And he's always looking for potential converts. A few weeks after that conversation, he took me flying.

It was a brilliant summer day in the Cotswolds, the flying club a broad acreage of cracked, grass-tufted concrete that once witnessed the rumbling of a hundred Lancaster bombers. As soon as we were airborne, Peter showed me how the pedals and joystick worked, and gave me the controls of the two-seater. We climbed away from the bosomy hills, levelling at 5,000 feet where we scampered among clouds of teased candyfloss. One was the shape of a doughnut, and I couldn't resist flying straight through the hole. It was a delirious sensation, and I began to laugh. I felt, I told him giggling, like an angel.

Peter looked at me askance. 'I've had some weird reactions taking people flying, but this is the first time anyone thought they were an angel!'

I have dreamt of flying since childhood - but who hasn't? Didn't most of us spend childhood nights flying, reliving the weightless suspension of the womb? My dreams were so vivid and familiar - they would always begin with me gliding, chest-down like Superman but mesmerically slowly, out of my room, along the landing and down the Burgundy-red stair carpet - that I was convinced of their literal reality: at night, while others slept, I flew.

I grew up in the countryside a few miles from Farnborough, and during the annual airshow I could look up from our back lawn to see the Battle of Britain Memorial Flight pass overhead. It was rare on any summer day for five minutes to go by without the sound of an aeroplane, and we would shade our eyes and wait to capture the silver flash like a fish as it passed, straight and fast, between the chimney and the woods, and we'd try to read its shape against the sky. Now, perversely, I am reassured when the summer silence of the British countryside - the hum of bees, the distant lowing of cows - is disturbed by the faint rumble of an aero engine. This, the rumble says, is how it should be.

A few years back I started work on a book about the world's deserts. Early one chilly desert morning on my two-year journey I was standing at the small aerodrome of Nazca, in Peru. The rising sun was staining the jagged Andes red. I climbed into a four-seat Cessna and the pilot, Carlos, fired up the engine.

Some things only make sense from the air. Dawn is the best moment to appreciate the Nazca lines, when the shallow ridges are shadowed by the low sun, and the air is clear and vapourless. Climbing over the pampas we soon saw them: hundreds of straight lines scoring the desert, and animal shapes, including the iconic hummingbird with its wings outstretched. They seemed smaller than I expected.

'It's because of our height,' yelled Carlos. 'They're a long way down.'

'Well, can't we go a bit lower?'

We dropped out of the dawn-pink sky to buzz the drawings. As we banked tightly they whirled around us - monkey, dog, 'owlman', spider.

No one knows why, 1,500 years ago, Nazcans engraved these lines into the desert crust. Erich von Daniken's Chariots of the Gods claimed that they were landing-strips for alien spacecraft; a more plausible theory suggests they played a role in hallucinogenic rituals. Andean museum collections groan with the paraphernalia of shamanistic drug-use, and it was - is - common for shamans in these psychedelic trances to identify with some symbolic creature. Frequently they believe their spirits take to the sky, and soar. Each of the creatures on the Nazcan crust is etched in a single line. Perhaps they were paths, walked by the shamans during their possession by the animal - spiritual, not alien, runways from which the shaman's soul took flight.

A few months after that flight, I found myself in the Peruvian Amazon, sitting in a wooden cabin with the velvet night sky overhead and the jungle raucous with insects. A shaman and I had been into the jungle and found the ayahuasca vine, and back at his village had boiled it into a thick, bilious stew. There were four of us on the oil lamp-lit porch, two of them women smoking tobacco pipes. The shaman passed the potion, and while we sipped he hummed a tune, an invocation to the spirits of ayahuasca. Soon the visions began: I was airborne, flying over endless fantastic cityscapes, their gothic towers and frothing parks delirious shades of crimson, lime-green and turquoise.

My friend Peter was surely right that as long as man has had an imagination he has dreamt of flight. Fortifications have been constructed at the highest elevations for strategic purposes, but we are also drawn to mountaintops for reasons of the soul. Hilary's conquest of Everest had for the British, in the year of Queen Elizabeth II's coronation, some profounder meaning than a mere sporting record. Close to Everest is the fabulous Mount Meru, navel of the earth, abode of the Hindu gods. The gods of the Greeks and Romans also inhabited the heavens - as do the Trinity and angels, and all the virtuous souls, of Christianity.

The centenary of man's first powered flight occurs in two years' time. Orville and Wilbur Wright's Flyer III was a cumbersome machine, its kite-like forward rudder and complex controls in many ways an aeronautical cul-de-sac (it was Blériot's Channel-crossing monoplane that standardised the aeroplane form we know today); but the Flyer changed the world for ever, possibly for the worse. In Baden-Powell's words: 'Wilbur Wright is in possession of a power which controls the fate of nations.'

When did humans first fly? The 1965 movie Those Magnificent Men In Their Flying Machines began with a slapstick montage of fur-clad cavemen futilely flapping their arms, and early aviators on primitive hang-gliders dropping like stones. The Chinese had constructed kites of tremendous sophistication and scale by the third century AD, and it's at least possible that people - clinging on or strapped on - took to the air. Everyone knows about the 'balloonist' craze that swept Europe in the eighteenth century in the wake of the Montgolfier brothers' hot-air ascents. But what about Sir George Cayley, MP for Scarborough, who launched a manned glider in 1848? If even a French aviation authority can call Cayley 'the true inventor of the aeroplane and one of the most powerful geniuses in the history of aviation', then it must be true - yet he languishes in obscurity.

As for me, I continued to experience livid, full-colour flying dreams into my late teens. If they stopped, perhaps it is because, as the shrinks tell us, flying dreams are associated with sexual longing. I suspect that the improvement in my sex life grounded my dreams. But I seized every opportunity that came my way to fly small aircraft.

I was in Kenya when I realised that the subject of my next book would be flight. A contact at Unesco's Nairobi desertification programme had introduced me to his son, a keen amateur pilot, who invited me to go flying with him over the Rift Valley. The problem was, neither of us had enough money to rent a plane. The following afternoon we went out to the airport, and hung around the pilot's clubroom until someone offered to take us up. It was a stunning flight, swooping around the emerald craters of the valley's extinct volcanoes. I discovered something valuable that day: that the owner of a pilot's licence can walk into an aerodrome, get chatting to fellow pilots, and stand a good chance of being offered a ride. Suddenly I had an image of myself 'hitch-hiking' by small plane from one aerodrome to the next - and the idea of Winging It was born, a journey around the planet celebrating the many facets of manned flight - a journey I'll be describing in The Observer over the next few months.

So it was that on a glittering late summer afternoon four months ago I found myself at an Ontario airfield, with six weeks in which to gain a flying licence. It was my first day at the school, and I was eager to be up in the air. Who knew how long the weather would hold? Within four hours of climbing off the Airbus, I was at the controls of a Cessna 152.

Tim Coombs, my instructor, had shown me the Walk Around: like pioneer aviators, pilots still begin every flight with a physical inspection of the plane, waggling ailerons and rudder, poking a stick in the fuel tank to check the fuel level (gauges can be unreliable), and carefully monitoring the engine's performance. To the uninitiated this behaviour implies severe doubts about the plane's airworthiness, but this is the aviator's Highway Code: when cars break down, you coast onto the hard shoulder, but aeroplanes are less forgiving, so they simply aren't allowed to go wrong. Instructors like to build your confidence fast, and they usually have you take off first time (it's landing that requires the skill). With a delicate shudder the fragile three-wheeled machine takes off, a winged Reliant Robin improbably airborne.

Within a fortnight I was learning how to enter and recover from the spins and spiral dives we've all seen in war movies, manoeuvres which place the pilot within seconds of death. I began by dreading these nauseating exercises, but ended up taking a grim pleasure in being able to pull them off (that is, pull out of them); maybe one day I'll even start to like them. Certainly, they give you confidence in your ability to handle a plane. The British have removed these perilous techniques from the flying syllabus - making us, according to one Canadian pilot, 'a bunch of woossies'.

Over the next six weeks I flew tiny trainers, a bulbous, leather-seated vintage Cessna (the 1954 equivalent of business jet) and a floatplane that scudded over the placid, pea-green lakes of northern Ontario. Cruising at 95 knots, I learned that unlike cars, planes can crash from being flown too slowly: the air passing over the wings is suddenly insufficient to generate lift, and the plane 'stalls'.

This usually occurs when a pilot is so intent on giving passengers a bird's-eye-view of, say, his new swimming pool, that he takes his eye off the speedo. A plane stalling at 3,000 feet picks up speed as it drops, quickly generates lift, and can resume flight; stall it at 500 feet, however, and before you know it your propeller is ploughing its way across a field, which in the mordant words of my instructor Tim, 'exceeds its design specification'.

I was learning to fly with half-dozen trainee commercial pilots, and conversation often revolved around aviation's unspoken freemasonic secret: the fact that it's dangerous. (Q: 'What's the definition of a good landing? A: One that you can walk away from.') Pilots naturally tend to a gallows humour: they know theirs is a job where failure can wipe the smiles off 300 holidaymakers. I've never forgotten the visual gag in Airplane, where the in-flight movie contentedly watched by passive, post-prandial passengers is a montage of aircraft crashes and great balls of fire. When I first saw the film the audience's laughter was edged with hysteria - this was a taboo flamboyantly transgressed, a joke that stirred our most assiduously buried fears.

The airliner is an aseptic high technology, close for most of us to brain surgery and rocket science. We all made paper aeroplanes at school, but the spectacle of a 365-ton jumbo jet ponderously mounting the air fills us with a superstitious sense of nature violated.

Consider the morbid press ecstasies whenever one of the slender aluminium tubes plunges into ocean, mountain or municipal housing unit. We are happy to drive along a wet motorway at 90 with spouse and new-born sleeping beside us - that's acceptable risk (it's a statistical fact that planes are safer than family cars); but when Concorde, with its hitherto 100 per cent safety record, experiences a freak accident, we are irrationally disturbed.

In flight, we behave as though we're not. The cabin staff's professional grins, the videos and Muzak all conspire to distract us from the terrifying miracle of flight. Magic seeks to appease the Gods, and flight is unquestionably magic; passengers know they have propitiated no one, signed no Faustian pact - they are exposed. Just two trembling wings and a clutch of fallible engines keep them airborne. And what about Human Error? The technology depends on two gold-braided fly-boys (they're usually male) up front, and recent events (the Russian pilot who let his knee-dandled son plough a plane into the ground, those heavy-drinking BA pilots) have taught us they're not angels. Taxiing up to take-off one morning, my plane skewed to the left. I shut the engine down and went to look for Paul, the mechanic. I found him with his head inside a deconstructed Cessna.

'Paul, I have a Situation.'

'Whassat?'

'Left brake locked on taxi.'

He pulled himself out of the fuselage, wiped his hands on his overalls and picked up a hammer.

'Is that what you need?' I asked.

'It fixes most things.'

He beat the brake pads and, achieving no result, grunted and stuck his head under the dashboard. I went to find a coat against the Canadian autumn winds. When I returned, Paul was smiling. 'You're lucky it didn't lock a couple of minutes later, when you were landing. Woulda spun you right off the runway.'

'Oh. Is it safe now?'

'Safe is a relative term, my friend. I keep both my feet on the ground.'

In the mid-1960s, my father took a job with the UN, and we as a family were en route to Turkey via Rome. The era of flight as mass transit had arrived with the plane we were flying - a Boeing 707 - but flight was still romantic then, and Pan American had yet to become a victim of deregulated airways and go bust. Our Boeing was curvaceous, and the miniskirted hostesses who wore crisp, virtually seamless dresses like those in Kubrick's 2001 gave us children crayons and colouring books. The outline drawings all showed airliners and airports, and trilbied, suited emissaries of capitalism grinning as they passed through sleek and streamlined terminals, utopian symbols of Modernity. What happened to it all? When did the giddy romance of flight implode into the banality of mass tourism, where every grey terminal resembles every other, with the numbing inevitabilities of the X-ray machine and the stuttering Baggage Claim carousel?

Yet there are still thousands of courageous, wary figures who wrestle small planes over deserts and choppy seas and fog-covered mountains - planes that have changed little technically in 50 years. There are pilots who live in hangars, sleeping beside their planes, and others who have devoted their lives and chequebooks to the preservation of ancient, impossibly exotic aircraft. Then there are the half-mad aerobatics junkies, the air racers, the exhibition pilots who risk everything to thrill a jaded crowd, and meet their deaths at airshows with sickening regularity. It was to encounter these pilots, all over the world, that I decided to set off on the journey I'll be describing in The Observer.

My most memorable flight as a pilot so far came after six weeks in the Canadian skies, soon after I gained my licence. It stirred me (it still does) to wake up and see the leather wallet with Pilot Licence printed on it in gold sitting on the bedside table. That day I woke up early to a bright, cloudless winter sky. Perfect. At the aerodrome I tugged my plane round into the sun's first copper rays, and as they melted the fine layer of iced dew on the wings I completed the flyer's ritual, checking ailerons and rudder and poking a length of dowling into the fuel tanks to be sure that the cockpit gauges didn't lie.

Climb in, headphones on, fire her up, taxi onto the runway. Add full power, and the engine is almost brutally alive, the prop jerking the fuselage forward as you accelerate to 10,000 rpm. At around 55 knots you ease back the stick, and there it is - weightlessness, gravity-defiance, the instant miracle of flight, the landscape falling away from you, emerald streaked with early-morning gold.

Winging it

Martin Buckley sets off this week on his global journey by small aircraft. He begins with a pilgrimage to the workshop in Scarborough where Sir George Cayley built the first manned glider. But soon he will be flying to Paris, Marseilles and on to North Africa. Observer readers can share Buckley's experiences as he files a fortnightly column from 21 January in Escape based on his research for Winging It, a travel book celebrating manned flight around the world. If you have information to share, you can also contact him en route by emailing mbwingingit@hotmail.com. Buckley's first book Grains of Sand is published in paperback on 29 March (Vintage, £7.99).