Japan Airlines and Airbus said the Japanese carrier, also known as JAL, would buy 31 A350 wide-body jets, which are expected to replace Boeing 777s in the carrier's long-haul lineup. Airbus is set to begin deliveries of the A350, a new plane that made its first test flight in June, to JAL in 2019.

Airbus and Boeing have been jousting for global leadership for years, with Boeing regaining the top spot in orders last year for the first time in a decade. Airbus long ago pushed into other Asian markets like China. But Japan, where Boeing has been firmly entrenched since the end of World War II, has remained unusually loyal to the American company. JAL had never bought a plane from Airbus, and JAL's main domestic rival, All Nippon Airways, operates mostly Boeing jets.

"Certainly this is the big order Airbus was hoping for, the big foot in the door that could lead to new orders," said Will Horton, an analyst at the CAPA Center for Aviation in Hong Kong.

Fabrice Brégier, the Airbus chief executive, said he had been courting JAL executives intently since taking over last year. Mr. Brégier, who worked in Japan early in his career for Pechiney, the French metals company, spoke a few words in halting Japanese at a news conference in Tokyo before switching to English.

"I have tried to give the best of Airbus to convince JAL that it was a no-brainer to select Airbus," he said. "I think in the past Airbus did not work closely enough with potential customers in Japan."

Japan is the second-largest air travel market in Asia behind China, although China is growing faster. Boeing has 428 passenger and cargo planes in service in the country, compared with 61 for Airbus, according to Ascend, an aviation consulting firm. In China, by contrast, the two manufacturers are neck and neck, with more than 950 planes each in operation.

Airbus and Boeing expect the Asia-Pacific market to yield 35 percent to 40 percent of all deliveries of new passenger planes over the next two decades. The bulk of those orders is expected to come from airlines in China, India and Southeast Asia, and most will likely be for smaller, single-aisle workhorses like the Airbus A320 and the Boeing 737, which airlines use on high-frequency routes over relatively short distances.

But Japanese carriers' need for fuel-efficient, long-range jets like the Airbus A350, the Boeing 787 and a forthcoming stretch version of the Boeing 777 are expected to increase significantly in the next 20 years as growth in intercontinental traffic between Japan and the rest of the world far outpaces expected growth in the domestic market of less than 2 percent per year.

The longstanding ties between the Japanese carriers and Boeing have also been subject to new tensions over problems with the 787, one of Boeing's newest planes. Both All Nippon and JAL have bought 787s, and a substantial portion of the planes' manufacturing takes place in Japan. Mitsubishi Heavy Industries, for example, makes the wings.

But the introduction of the 787 was delayed several times, with the first delivery, to All Nippon, coming in 2011. Then, earlier this year, the plane was grounded for months by problems with batteries, causing scheduling and logistical difficulties for the Japanese carriers and other 787 customers.

"I think it played a significant role in this decision," said Geoffrey Tudor, an analyst at Japan Aviation Management Research in Tokyo, and a former JAL executive, referring to the grounding of the 787.

However, JAL's president, Yoshiharu Ueki, said the choice to buy the A350 had "nothing to do with that situation," saying that JAL had chosen the A350 for other reasons, including an expectation of low operating costs. Like the 787, the A350 uses a substantial amount of lightweight composite material in its structure, lowering the weight and fuel consumption.

Hisako Ueno contributed reporting from Tokyo, and Nicola Clark from Paris.