The airline business has been firmly in the doldrums ever since the tragedy of 11 September.

But Boeing, the biggest maker of aircraft in the world, is putting down a marker for when things bounce back by planning to update its most well-known jetliner, the 747.

The new 747-400XQLRl, the company announced at the Singapore Air Show, will fly further and more quietly, and is scheduled to come into service in 2004 after flight tests next year.

It is intended to take the shine of European competitor Airbus's plans for a "super-jumbo" of its own.

The current 747's maximum capacity of about 400 passengers would be dwarfed by the A380, which - when launched in 2006 - should hold more than 500.

'Size doesn't matter'

Boeing believes that bigger is not necessarily better, and that its customers are more interested in range and in meeting new European noise standards.

"If we wanted to make it bigger, we could make it bigger," senior vice president of sales Larry Dickinson told reporters.

"What we've been told is that this is the size of airplane customers want. There's a 500-seater if you want to buy one. But nobody is telling us they want a bigger airplane."

The new jetliner's range is to be 9,190 miles: only a 4% increase on current range, but according to Boeing that would be enough to take the plane from New York to Bangkok non-stop.

Existing 747s can go no further than the New York-Hong Kong run.

One on one

Boeing, which is shedding 30,000 staff and saw profits slide $600m last year, is locked in a head-to-head tussle with Airbus, and, as is the case with most air shows, this one is about each of the two rivals trying to outdo the other.

Part of the justification for the new 747, some observers remark, is that Boeing has scrapped its own "super-jumbo" plans in favour of a "sonic cruiser", a near-supersonic jet which it hopes to have in the air by 2008.

Both are also trying to shake off the gloom shrouding the aviation world, which has seen General Electric shell out more than $4.1bn in vendor financing to try to keep airlines shopping.

Airbus's owner EADS, meanwhile, is focusing its comments on the defence business.

EADS said at the show that its defence division would turn profitable this year.

The company is starting on pilotless planes, and also plans to win more business in Asia.