I knew we were in trouble when the man in the shiny suit appeared with a trolley of bottled water and granola bars.

Our British Airways flight from Vancouver had already been delayed twice - trouble refuelling and trouble finding somewhere to dock - but even as we walked into the crowded but strangely inactive baggage hall in the new Terminal 5, nobody was telling us that we had just flown into the sort of fiasco that the British seem to do so particularly well.

Queues had already formed at the customer assistance desks but the smiling, slightly wild-eyed staff had almost nothing to offer. Even after six hours of chaos, nobody had been briefed. Nobody knew anything. The desks, probably knocked together by a carpenter some time during the night, were bare. I'm not even sure they had telephones. Not that it would have helped if they had. "I have tried calling," one young woman told me, waving a sheet of contact numbers. "But nobody's answering." So, £4.3bn spent. Fifteen years to complete. All manner of planning stipulations flouted. (In 2001, even the possibility of a third runway was deemed "totally unacceptable".) And all to create what the Queen in her opening address called "a 21st-century gateway to Britain". It felt more like a 19th-century doorway to Calcutta from where I was sitting.

According to the press, BA and the BAA were at each other's throats from the moment things began to go wrong, ie almost from the second that this wretched place opened. This was certainly reflected at ground level.

As the jet-lagged crowd slumped on the floor in the vast baggage claim area (the genius of the Richard Rogers Partnership did not extend to a single chair or bench), BAA officials were keen to impress on us that they had done their job. The lights were on. The conveyor belts were turning. BA officials meanwhile blamed the BAA computer systems. And all the time, every 10 minutes, an Essex voice was cheerily announcing in a loop designed to send even a strong man insane: "British Airways would like to apologise for the delay to baggage collection. British Airways are doing their best to address the situation."

"Why can't you give out some proper information?" I asked a BA manager. "We can't," he wailed. "We don't have any - and anyway, they haven't given us a Tannoy."

Since then, Willie Walsh, the chief executive of BA, has been doing the rounds with a bizarre performance of mea culpa. He is entirely to blame for the poor performance, he tells us. "I apologise to everyone and anyone." Strangely, this apology doesn't extend to his resignation for what he admits was "a public relations disaster" for his airline and which Nigel Turner, chief executive of BMI, called "a severe embarrassment for the United Kingdom".

Indeed, how is one to respond to this latest disaster, and what does it augur for the London Olympics in 2012? How are we going to feel when the Olympic torch turns up in Walthamstow three days after the opening ceremony?

What is so depressing is that T5 so obviously repeats the pattern of the Millennium Dome, Wembley stadium and the Scottish parliament which, you may remember, arrived three years late and 10-times over budget. When that unlovely building opened, Jack McConnell, the Scottish first minister, said: "It's what we do in the building that really matters." And that, I suppose, is also true of Terminal 5.

Except that what we do in T5 is to try to get out of it as quickly as possible. Some people have praised Richard Rogers' design, with its sense of scale and space, the use of natural light, the vast steel arches and back-painted glass. But who really cares? There is not a shred of glamour or excitement in an oversized shed in the back end of Southall, even if you can shop at Paul Smith and get a meal cooked (as if) by Gordon Ramsay. We go to airports reluctantly. We leave them with heart-felt relief.

Speaking for myself, I have arrived at that very fine line when I wonder if a two-week holiday in the sun or the snow is actually worth the ordeal of air travel - the Byzantine ticket pricing schemes, the invasive and tedious security lines, the crying babies, the unexplained delays, before you get on to the plane, while you sit on the runway silently begging air traffic control to end the torture and give you a precious "slot", and while you wait for your suitcase which will always be the last off the carousel, even assuming that it's actually on it ... The sheer misery of the whole experience. Is there anyone who goes on holiday (and 80% of air travel in the UK is leisure based) without the dread of the journey back again?

And I'm beginning to see that there are alternatives. The real "21st-century gateway" that opened this year did so at St Pancras, and it did so with enormous style and comfort. All of Europe is suddenly available and I can reach it in less time than my bags reached me. All the signs are that air travel is going to get worse. Fuel prices and tax are going up. Air space is decreasing. The cabin crews are getting smugger.

The one thing I didn't see at Heathrow was the expected demonstration by environmental groups such as Greenpeace or Plane Stupid. But perhaps they weren't needed. There were, after all, thousands of people protesting for them, albeit in a rather lacklustre and disorganised way. They were called passengers.

And at the end of the day, it is their voice that may put an end to the vexed question of airport expansion. The bigger it gets the worse it gets, and I'd guess that modern air travel carries with it the seeds of its own destruction. There will have to come a time when everyone decides that anything is better than seat 27K behind the lavatory... even staying at home.

The environmentalists only have to wait, because in the end they've simply got to win.

· Anthony Horowitz is the author of the Alex Rider book series