A340-300 burns 15% to 20% more fuel per seat

Airlines say the 777 is beating the A340 because it is newer, less expensive to fuel and maintain, and more reliable. Tim Clark, president of Emirates, said that its new 777-300ERs have had fewer problems than its new A340-500s. The 777 has "exceeded all its planned performance criteria" for fuel consumption and range, Mr. Clark said. "That's why there's a resurgence of interest" in the 777.

The Boeing 777 is more fuel-efficient and less costly to maintain because it has two engines rather than four. Airbus officials said the A340 operates economically and that four engines offer airlines greater security and reliability than two.

Air Canada Chairman Robert Milton said in April that the carrier chose to replace its A340s with 777s because they "have considerable economic efficiencies" compared with the Airbus models. He said that "had a very dramatic impact on the decision."

Air France, another major Airbus customer but also a big 777 buyer, is one of few carriers that has flown both A340s and 777s on the same routes. Chief Financial Officer Philippe Calavia said a first-generation A340-300 from the 1990s burns about 15% to 20% more fuel per seat than a 777 of the same vintage. "It's more costly to maintain four engines than two," he said, adding that Air France expects "to further increase the proportion of 777s in our fleet."
WSJ January 16, 2006