And what an extraordinary industry it is. It is so normal in the sense that we use its services, either directly by travelling or indirectly by buying goods flown round the world, almost every day. And it is extraordinary in that the commercial risks that its main companies are obliged to take are greater than those of any other industry in the world.

That is why there is room for only two big airframe manufacturers, Boeing and Airbus . . . both in rather different ways relying on government support . . . and three big engine manufacturers, General Electric, Rolls-Royce and United Technologies.

It is reasonably easy to start an airline. That happens all the time. But it is unthinkably difficult to enter the airframe business, and the world is lucky in a way to have two companies that can make large commercial aircraft, not just one.

So aviation is an industry story, but it is also an energy and environmental story, for obvious reasons. And finally it is a globalisation story, for aircraft rank alongside telecommunications as one of the two great drivers of our ever-more global world economy.

The industry story is widely understood. Airbus is in the doghouse, with delays on the super-jumbo, the A380, and a forced redesign of its new mid-size aircraft, the A350. Management was sacked. Boeing, by contrast, is riding high. But two years ago the reverse was true. Airbus was getting far more new orders and Boeing was mired in scandal.

The super-jumbo may or may not be a commercial success. My instinct is that the market is not big enough for it to pay back its development costs, but to say that may be to underestimate the growth of air travel in Asia.

The company, however, will not be allowed to fail and in 20 years we will still have two big airframe manufacturers. We will also have three engine manufacturers, or more likely two-and-a-half, for United Technologies has been losing ground to GE and RollsRoyce.

But the big point here is that this is an industry that delivers products that work with astounding reliability and ever-increasing efficiency. Couple that with the parallel revolution in efficiency by airlines . . . call it the Ryanair revolution . . . and you have a global industry that is really very good at what it does.

Of course we all get irritated if we are held up for some reason, but the overall experience is remarkably consistent and much of the time, very cheap. I find it intriguing how the budget airlines figure out those tiny changes that save time and money, such as Ryanair's elimination of pockets on the backs of seats, and wish a similar drive for efficiency were as evident in other walks of life. If only the tax authorities were as efficient as Ryanair at getting rid of paperwork. . . well, maybe not.

It is an industry that will carry on with incremental improvements for the foreseeable future, and where huge technological breakthroughs are unlikely. The new generation of aircraft now on the drawing board will still be in service in another 40 years. And that has important environmental implications.

In round terms, improved efficiency is offsetting about half the environmental damage done globally by increased air travel. That is a considerable achievement, but we are still losing ground.

We will lose more ground as the boom in air transport spreads across Asia. And unlike most other forms of energy use, with air transport there is really no substitute for oil.

Oil remains the scarcest of the world's energy resources.

There seems to be evidence that, by releasing hydrocarbons in the upper atmosphere, aircraft are particularly polluting. For journeys of more than about 500 miles, there is really no competitive alternative. And high-speed trains are pretty polluting too, when you allow for power loss in transmission and other energy costs.

So I think we have to accept that the more successful air transport is, the greater the environmental impact it will have. At the moment, the carbon imprint is quite small relative to other uses of fossil fuels, but it will grow. The only thing that might stop it is the end of the march to an ever more global world.

Try and imagine if air transport and travel actually shrank. International tourism would become once again the privilege of the rich . . . the time-rich as well as the money-rich. Trade in highvalue exports would decline.

Countries that were far from their markets would suffer: it would be bad to be Iceland or Estonia. Scotland, Wales and Ireland would suffer relative to England. It would be particularly bad news for Africa, which is unusually dependent on air transport.

Moving people and goods around is the very core of globalisation, which is in turn the driver of the present burst of global prosperity.

Those who argue that air travel has become too easy, and there are many who feel that, have not I suspect thought through the consequences of making it more difficult. I suppose some people do travel frivolously. One of my former colleagues once went to New York for a haircut: I rather admired her for that. I suppose you could say that having a stag party in Dublin or Prague is frivolous when you can drink just as much at home, or going to Germany to watch a football match when you can see it on the box.

But . . . and this is the key point . . . cheaper air travel, along with much cheaper telecommunications, is at the core of the greatest period of sustained prosperity that the world has ever known.

The hundreds of thousands of foreign nationals working here did not come by boat.

It is the practical way we get to know each other, get to understand and, I would hope, respect other cultures.

Sure, we are allowed, when reading about the travails of the Airbus super-jumbo, or worrying about a noisy plane overhead, to appreciate that aviation has its flaws. But at the same time we should recognise how lucky we are to be able to move about the world, thanks to the industry's astounding technology.

And we should not try to deny other people with less money the privileges and freedoms that we enjoy.