Flying is all too often a purgatorial nightmare, and the burgeoning travel industry can only make things worse. What can architects do to restore the magic?
Airports tell the story of this century as well as any type of building you can think of; the transformations of scale, technology and aesthetics offer a telling index of new realities, not to mention fantasies. There is no bigger challenge to designers, architects, and all the others involved in making air travel feel like the cutting edge of experience rather than the purgatorial waiting, searching, trekking and shopping places they have all too often become.

First the bedrock practicalities. The growth in air travel is exponential; how to cope with it? What happens when two big-bellied planes each carrying 800 passengers both disgorge at the same time?

Over the next 10 years the British Airports Authority will invest more than pounds 1m a day on new buildings. Already at Heathrow Terminal 3 the architect, Nicholas Grimshaw, is building an extension for a new check-in, retail and office buildings and Llewelyn-Davies is extending the front of Terminal 2. These are familiar spaces. What will revolutionise Heathrow are the introduction of the Heathrow Express (a high-speed link from Paddington) and, most dramatically, the putative new Terminal 5, conceived by Richard Rogers' company. It is the subject of a public enquiry that will announce its findings next April. It may yet take the Government some time to evaluate the results. So Terminal 5 may be the airport of the future or just a sci-fi fantasy.

A light, airy, transparent building with a distinctive curvy roof, it floats above the landscape in an undulating wave. The core is a central atrium about 35m tall, around which are satellites with aeroplanes parked along them like toast in toast-racks. The modular structure is made from sections of arches, the most effective way to span large distances. Bands of roof glazing and glass walls bathe the airport in daylight because the architects feel it is imperative to bring back some of the magic of travel and to do that, you need to see the planes. Inside, louvres, angled walls, fabric canopies and eave overhangs will act like baffles to control light emission at night. Passengers on the Heathrow Express and on the Underground will disembark at the base of the core building and enjoy spectacular views through all levels of the building. In a move away from the radical expressionism of Lloyd's of London, Rogers' new building takes a softer, more organic, site-responsive approach. The only element visible from Windsor Castle, Osterley House and Richmond Hill is the thin steel tube of the 87m air-traffic control tower, stabilised with high-tension steel cables. But then a lot of people live closer to the building than the Royal Family and as sensitive as the look of the building are the noise and light pollution issues. A senior partner of Rogers, the architect John Young, argued passionately for the Terminal, which is destined to carry 30 million passengers a year, nearly half of Heathrow's predicted total by 2005.

To address the issues of the airports of the future, Raymond Turner, head of design at British Airports Authority, has assembled a think-tank headed by Sir John Egan.

In their efforts to get to grips with the future, the group sift through predictions by weather forecasters, behavioural scientists, sociologists, architects and designers to identify trends. Helping them are four outsiders: the Milan-based architect and designer Vico Magistretti, who thinks the London Underground map is Britain's best design product; Nick Butler, designer of that neat black and yellow pocket torch that switches on when you flip the lid; Rodney Fitch, who marketed the Saudis at Expo '92 as having tourist potential alongside a cutting-edge petrochemical industry; and Chris Ludlow, who's a whizz on corporate identity in an age of global cloning. They have to decide whether the trend identified is a probability or a possibility. "If it's a probability, we have to make a business decision," says Turner.

Changing weather patterns are taken seriously at BAA. Weather forecasters warn that though rain levels are not expected to drop in the UK, more rain will fall in heavy showers with long periods of drought in between. So BAA plans to instal radial guttering at all its airports, which will channel rainwater into tanks for storage and recycling.

By 2010, a third of the world population will be 65 years and older. Seasoned travellers by then, but needing golf-buggy conveyors to board the plane, wheelchair fork lifts, bigger signs, clearer announcements.

Shopping patterns are changing too, with the Net. Instead of trying on the fake tan from a sample at the Body Shop, we'll tap into the World Wide Web sites and punch in an order with plastic to await delivery at our destination. "Why do people go to the airport, get rid of their luggage and pick up more luggage to carry on board the plane?" Turner asks.

By 2010 passengers may be wearing wrist straps that contain personal information. So check-in knows in advance that you fear flying. Your heart rate goes up when you are scared so your "intelligent agent" or minder sends this info ahead so that check-in can give you beta-blockers with your boarding pass.

And finally, that luggage nightmare. Think how you drag your suitcase round to the airport, check it in, watch it disappear while you go up the same sort of cigar-tube escalators and dreary route to the plane, rejoin it on board yet are separated from it, only to be reunited again at the carousel at the end of your journey with still some way to go to unpacking it all. In the future suitcases may be air-couriered door to door from your home to your destination with all the security surveillance that top technology can throw at it, and no input from you. Now that would give the heart lift-offn

`Airport', a photographic and video exhibition sponsored by BAA, opens at the Photographers' Gallery, 5 Great Newport Street, London WC2, 4 September. A second exhibition also called `Airport' and sponsored by BAA, featuring five international airports, opens at the Architectural Association 29 September.