Nov. 11 (Bloomberg) -- Airbus SAS, the world's largest manufacturer of commercial planes, won an order from Emirates for aircraft valued at as much as $31 billion, including 70 A350 airliners and 11 double-decker A380s.

Emirates, the biggest Arab airline, placed a firm order for 70 A350s and took options for 50 more, Chairman Sheikh Ahmed bin Saeed al-Maktoum said today at the Dubai Air Show. The carrier bought about $34.3 billion in aircraft today, including a purchase from Boeing Co., the No. 2 planemaker, worth about one-tenth of the Airbus order.

The Airbus deal is a boost for the 300-seat A350, the planemaker's challenger to Boeing's 787, which is cheaper and due to enter service five years ahead of the Airbus model. The A350 was delayed because Airbus redesigned the plane several times to meet demands from airlines. The A380 order gives Dubai-based Emirates a backlog of 58, making it the largest customer for the superjumbo.

``It's a tremendous win for the A350,'' said Nick Cunningham, an analyst with Evolution Securities in London. ``It validates the program and is exactly what it needs to get it off the ground.''

With the Emirates order booked today, Airbus has 266 firm contracts for the A350 and 98 commitments. The A350 order from Emirates, including options, is valued at $27.6 billion at list prices, and the A380s are worth $3.5 billion. List prices do not take into account discounts usually given for large purchases.

``The 350 was the most suitable aircraft for our type of mission,'' al-Maktoum said at a press conference. Asked why Emirates chose Airbus over Boeing, airline President Tim Clark said: ``The 787-9 wasn't suitable for us and the 787-10 wasn't available to us.'' Emirates is willing to talk to Boeing when the 787-10 is available, he said.

Boeing `Too Fragile'

Boeing's 787 program is ``too fragile at the moment,'' Cunningham said. The 787 Dreamliner model is due at the end of next year, six months later than planned. Boeing had 710 orders for the plane as of mid-October, the company's most successful sales effort for a new model.

Boeing hasn't formally offered the 787-10, a longer-range and bigger version of its 787-9. Boeing Commercial Airplanes President Scott Carson conceded that Boeing lost the Emirates order.

``Obviously Boeing would like to win every venture we're involved in,'' he said. ``We didn't have the airplane they wanted at this time.''

Emirates 777s

Chicago-based Boeing, the second-largest planemaker, won an order for 12 of its 777 aircraft valued at $3.2 billion from Emirates, the carrier also announced today. Emirates ordered the 777-300ER model, which has a list price of about $250 million.

Boeing also won a $6.1 billion order today for 30 of its 787 Dreamliner planes and five freighter 777s from Qatar Airways, the largest customer for Airbus's A350. The carrier took an option to buy 30 more 787s.

Airbus also sold A320s today valued at $2 billion to National Air Services, the first budget carrier in Saudi Arabia. NAS bought 20 planes and took options for 18 more.

Clark said last month that Boeing needed to increase the thrust available for the 787-10 before Emirates would consider an offer. The General Electric Co. GENX engine offered 75,000 pounds of thrust and Emirates wants 83,000, Clark said at the time.

Rolls-Royce Group Plc, the second-largest aircraft-engine maker after GE, would be able to offer the increased thrust, Chief Executive Officer John Rose said in an interview today.

Rolls-Royce

The Emirates order for A350s may be worth as much as $8.4 billion to London-based Rolls-Royce, which offers the only engine now available on the Airbus plane, Rose said in a statement.

Emirates started in 1985 with two leased planes and now has 110 aircraft including freighters. It had 112 planes on order as of Oct. 24. The airline has added destinations in China and India, betting that economic growth in Asia's two most populous countries will spur demand for travel.

``Many in the aviation community believe they've gone too far, and committing to an operation of that size is definitely a gamble,'' said Richard Pinkham, an analyst at the Centre for Asia Pacific Aviation in Singapore. ``But aviation experts have been leveling the same charge for years and thus far, at least, Emirates has continued to prove them wrong.''

Persian Gulf carriers including Abu Dhabi's Etihad, Qatar Airways and Emirates are among the biggest customers for Airbus and Boeing as the airlines build the region into a hub for tourism and transit flights between Europe, Asia and Africa. Airbus, based in Toulouse, France, is a division of European Aeronautic, Defense & Space Co.

Airbus Crisis

Airbus, struggling to end a financial crisis sparked by delays that put the double-decker A380 two years behind schedule, announced a reorganization Feb. 28 that includes 10,000 job cuts over four years and a move to find partners for six plants.

The 555-seat A380 overtook Boeing's 747 as the world's largest airliner after entering service with Singapore Airlines Ltd. last month. British Airways Plc said in September it will buy 12 A380 superjumbos valued at $4.3 billion.

Arab airlines are expected to increase their combined fleet almost two-thirds to 900 aircraft by 2015 from 550 in 2006, according to the Arab Air Carriers Organization.

Clark, the Emirates president, said the airline may consider issuing bonds to raise money for purchases, but that this wouldn't take place before 2009.

To contact the reporters on this story: Massoud A. Derhally in Dubai, United Arab Emirates at mderhally@bloomberg.net ; Andrea Rothman in Toulouse, France, at aerothman@bloomberg.net .