Distance Learning

The first problem is technology - stretching the range of a plane is a trade-off between space for passengers and cargo, and for the extra fuel. A derivative of the Airbus A340 has a theoretical maximum range of 15,000 miles, more than enough for any journey between two points on the surface of the earth. But it is doubtful that any airline could operate the plane at a profit. The best bet is the 8,500-mile range A340-500, due out in 2002, and the 777 derivative being considered by Boeing that could fly almost 10,000 miles.

Next problem: crews. The maximum working day is 16 hours - just enough to cover the longest scheduled flight, between New York and Hong Kong. Any further, and more crew and space has to be used.

Where's the demand? There are plenty of city-pairs within the capabilities of the 747-400 or A340: Perth-Buenos Aires, Lagos-Los Angeles, London- Bali, Cape Town-Melbourne. There are just not enough customers to justify these flights.

Joining the dots: these are among the few remaining city-pairs that could justify non-stops - if the technology becomes available: Chicago- Sydney (9,223 miles); New York-Singapore (9,545); Tokyo-Lima (9,608); London-Sydney (10,549).