In Papua New Guinea, almost overnight, air travel transformed a stone-age country into a 20th-century state. It brought remote hill tribesmen into the age of the computer, the flush lavatory, the English language and the tourist credit card. Now the sons of headhunters travel by air as a matter of course, both as passengers and crew. They share the same advantages, irritations and doubts as the rest of us.

Air travel today makes better sense when thrown into relief by what came before. In 1919, airline pilots followed railway lines expecting to make regular forced landings. But as wood and fabric bi-planes gave way to comfortable and reliable Empire flying-boats, service levels on the ground and in the air became more and more exclusive. Among all that we've gained, what have we lost?

The air conquest of the North Atlantic pit the aeroplane against the elements and against the airships - and of both against the ocean liners - in a race to the first commercial air service over the most prestigious route linking the New World with the Old.