Cathay Pacific Airways will review schedules and fares on long-haul routes as skyrocketing fuel costs put pressure on the airline's margins. 'Flying longer needs more fuel, and it has to burn fuel to carry fuel,' said the carrier's chief operating officer John Slosar. Long-haul flights had a higher percentage of fuel costs to total expenses per flight, he said. Jet fuel now accounts for more than 40 per cent of Cathay's total costs, compared with 30 per cent last year as kerosene rose to US$179 per tonne in Singapore last Friday. Cathay chief executive Tony Tyler said on May 16 that the carrier would reduce flights on or scrap cash-draining routes and would look at long-haul destinations first. 'The last thing we want to do is to cancel flights. [That would be] the last resort,' Mr Slosar said, adding that the route-adjustment decision would be made by year-end. As Cathay could book exchange gains from tickets sold in Europe because of the strong euro, routes to the United States are more vulnerable to service cuts. The airline is also looking at boosting revenue to offset rising costs. 'For the first time in a long period, the real cost of travelling is increasing,' Mr Slosar said. The real cost of travelling, which is inflation adjusted, has declined at a rate of 2 per cent per year over the past 40 years, helping to create a travel boom worldwide. 'People might travel less, and may no longer travel on holiday or send their children to study overseas,' Mr Slosar said. To lower fuel costs, Mr Slosar said Cathay had decided to replace the 20 plus Boeing 747-400 aircraft in its fleet that were more than 20 years old from 2013 with B777-300 ERs that consume 22 per cent less fuel per seat. The airline is also interested in more fuel-efficient models such as the Airbus 350 and Boeing 787.