THE battle of the superjumbos has hit new levels with European manufacturer Airbus accusing US rival Boeing of telling "big lies" about its double-decker A380.

While manufacturers have always sniped at each other’s usually conflicting comparisons of aircraft performance, Airbus says it is incensed at Boeing’s latest attempts to sell the 747-8, the stretch version of the venerable jumbo jet.

The Europeans are back on the offensive after being thrown into crisis earlier this year when production problems forced it to delay the delivery of the first A380s by another six months.

"Quite frankly, we have to put a few things right regarding the A380 compared with the 747-8 and their freighter stablemate because Boeing has just been putting what can only be termed big lies in the marketplace about the A380," Airbus A380 marketing director Richard Carcaillet said in Sydney this week.

Airbus has so far sold 159 of the double-decker planes to 16 customers, including 25 freighters.

It booked three new customers and 20 orders in 2005 and so far this year has sold an additional nine planes to Singapore Airlines.

It expects to announce more orders this year and says it already has half of the 16 major 747 operators as customers.

Boeing, which has yet to announce a major airline customer for the passenger version of the 747-8, claims the stretch 747 can beat the A380 on costs per seat as well as for a total trip.

It also contends the 747-8 is more structurally efficient than the A380 in terms of operating empty weight per seat.

The US plane maker has 29 orders and commitments for the new plane, including an agreement with former A380F customer Emirates to buy 10 freighters. But Airbus says Boeing is stretching a 40-year-old design to the limits compared with its completely new A380.

By contrast, it says, the A380 is at the start of its development cycle with stretch versions of the big plane still to come.

It expects to launch variants with greater range or bigger capacity as and when the market requires.

It also accuses Boeing of ignoring reality in its comparison between the two planes.

"What the airlines wanted, and asked us to provide, was an aircraft that is not only bigger but with more performance in terms of range, in particular, than the 747-400.

"And the A380 is 50 per cent more productive through the combination of more capacity and more range than the 747-400. In contrast to that, what Boeing are offering today … is only 16 per cent more productive.

"Why? Because they wanted, of course, to try and match the range of the A380 so they announced the same, or slightly better, range than the A380.

"In order to do that they are hitting the limits of the old 747 wing, which basically just has a minor tweak, and their capacity increase is only 8 per cent, instead of 35 per cent (for the A380), compared with the 747-400."

Other claims under dispute include the number of airports to which the A380 will fly - Boeing estimates about 30, while Airbus predicts around 70 by 2010 - and the way traffic growth will develop.

Airbus also argues the wider cabin on its plane will be more comfortable, allowing wider economy seats and giving airlines more scope to install the next generation of business and first-class suites.

It says the cabin will be quieter with low-speed airconditioning that will put an end to drafts.

But it is Boeing’s claims about the 747-8 that it has lower seat-mile costs and structural efficiency that have seriously raised Airbus’s dander.

Airbus says Boeing’s structural efficiency claim is invalid, that the 747-8 will be heavier than Boeing says it will be, and that cost comparisons fall convincingly in favour of the A380.

Mr Carcaillet said seat-mile costs on the A380 were 20 per cent lower than the 747-400 and 12 per cent lower than the 747-8.

He accused Boeing of putting "huge mark-ups" on the A380’s empty weight and fuel burn to enable it to show bigger differences than were actually the case.

He said Boeing’s estimates were in many cases double those used by Airbus.

This enabled Boeing to say the operating empty weight per seat of the 747-8 was 13 per cent below the A380 when it was only 7 per cent.

Boeing estimated the 747-8’s fuel burn per seat to be 14 per cent below the A380 but Airbus calculated that the double-decker plane was 5 per cent better.

"One of many erroneous statements that Boeing are putting out regularly and repeatedly in the marketplace is that the 747-8 is the lowest-cost large aircraft," he said. "It is basically wrong."

Mr Carcaillet said the discrepancies between the Boeing and Airbus claims about the A380 freighter were even worse.

The freighter version will be introduced into service two years after the passenger model and has been ordered by logistics giants UPS and Federal Express.

"Without going into too much detail, a big source of the incredible comparisons Boeing is putting out about the A380 freighter is that they assume … that the A380 freighter versus the 747-8 freighter weight difference is not 70 tonnes, as it is, but 85 tonnes," Mr Carcaillet said. "They just assume the aircraft will be so far off its target and it’s not."

Although not prepared to comment on whether Airbus would still deliver its first plane by the end of the year, Mr Carcaillet said the A380 was meeting all its performance guarantees.