DALLAS, US - US consumers will pay more to fly this summer than in 2007 and find fewer seats as carriers including American Airlines and United Airlines struggle with a 63 per cent jump in the price of jet fuel.

First-quarter fares rose about 7 per cent, said David Swierenga, president of consulting firm AeroEcon in Round Rock, Texas. He predicted on Tuesday that prices will increase 10-15 per cent in the high-demand summer season while airlines pare fuel use by cutting service or flying smaller planes.

Costlier tickets still could not stem collective operating losses last quarter of US$1.69 billion among the 10 largest US airlines. With the Air Transport Association predicting a 44 per cent jump in carriers' 2008 fuel bill and the prospect of capacity-trimming mergers, fares probably will keep climbing.

'If you're flying during the peak summer season, no matter how you look at it, you're going to end up paying more,' Tom Parsons, chief executive officer of Internet travel website Bestfares.com said in an interview.

'That's without any increases that may occur between now and then. And you'll see less flight options, fewer planes.'

US airlines have boosted fares or fuel surcharges at least nine times this year, not including Delta Air Lines Inc's round-trip surcharge of as much as US$40 begun on Monday. That pushed the round-trip fuel fee on some US flights to US$110.

Carriers, concerned that continued fare increases may drive away travellers, also are adding or boosting charges for optional items or services.

This month, the largest airlines will start charging US$25 to check a second bag, and some have bumped up ticket-change fees to as much as US$150. US Airways Group Inc will charge US$5 more for some aisle or window seats effective May 7, and JetBlue Airways Corp has a premium of as much as US$20 for seats with extra legroom.

'As price goes up, demand goes down,' Mr Swierenga said in an interview. 'Some travellers will opt out.'

Leisure fliers may pick closer, less expensive destinations, while some businesses may have to stop travelling sooner as the fares drain their budgets, he said.

Most major airlines have cut expansion plans for this year or next, grounding aircraft or delaying deliveries of new planes.

Delta is eliminating 2,000 non-pilot jobs through buyouts and voluntary retirements, while United, a unit of UAL Corp, is cutting 1,100 jobs. Delta also is betting that its plan to buy Northwest Airlines Corp will produce US$1 billion in new revenue and savings to overcome the surging fuel bills.

The Air Transport Association, the trade group for the major US airlines, says fares are still a bargain.

'In the US, the price to fly a mile is 46 per cent below levels dictated by inflation,' spokesman David Castelveter said in an interview. The average domestic fare to fly 1,000 miles is 0.5 per cent below 2000's level, while a gallon of jet fuel has more than doubled, he said.

Ticket prices need to rise as much as 20 per cent just for carriers to break even at current fuel prices, Delta CEO Richard Anderson said last week.

Crude oil, from which jet fuel is refined, has surged 74 per cent in the past 12 months, topping the 63 per cent leap for jet fuel.

Fuel has become the largest expense at many US carriers, surpassing labour. Losses among US airlines may total more than US$2.5 billion this year even as travel demand remains strong, according to Ray Needle, a Calyon Securities analyst in New York.

The Bloomberg US Airlines Index has slumped 24 per cent this year, with Southwest Airlines Co the only carrier posting a gain compared with declines for the 13 others.

'The consumer is going to see some pain' from higher fares and added fees, Mr Swierenga said. 'But the airlines are going to see some real hurt. They are going to have full airplanes and are going to be losing their shirts.' - Bloomberg