LONDON (Bloomberg) - British Airways Plc ordered 36 Airbus SAS and Boeing Co. planes valued at $8.2 billion, making its biggest purchase in nine years to keep pace with Virgin Atlantic Airways and fend off business-only carriers.

British Airways will buy 12 Airbus A380 super jumbos and 24 Boeing 787 Dreamliners, Chief Executive Officer Willie Walsh said today. The long-haul planes will be powered by Rolls-Royce Group Plc engines, with deliveries starting in 2010.

Adding the 525-seat A380 will increase capacity on flights to Hong Kong, Los Angeles and San Francisco from London Heathrow, where takeoff slots are limited. The Airbus was chosen over a new version of Boeing's 747 jumbo, of which the airline has 57 older models. The order will boost capacity by four percent annually, closing the gap on Virgin, whose passenger count rose 16 percent last year, eight times the pace at British Airways.

"British Airways needed to grow or face profit stagnation," said Chris Avery, an analyst at JP Morgan in London with a "neutral" rating on the stock. "BA has not expanded its long-haul fleet since 9/11, while competitors such as Virgin and the new business-class carriers have."

The smaller 787s, which seat about 250 people, will operate to New York and additional destinations the carrier plans to serve. The share of the contract for both Boeing and Airbus is about $4bn, based on list prices. Discounts may have cut the actual bill by a quarter, Collins Stewart Plc said in a note.

Shares of British Airways, Europe's third-largest airline, rose 15.25 pence, or 4.1 percent, to 384.25 pence, the sharpest advance since Aug. 13. That pares the stock's decline this year to 27 percent, giving a value of £4.43bn.

"The A380 will be used to provide more capacity for key high-density markets and maximize use of scarce Heathrow slots," Walsh said in a statement. "The 787 will start new routes and increase frequencies in existing markets."

European Aeronautic, Defence & Space Co., parent of Toulouse, France-based Airbus, closed down one cent at 21.07 euros after earlier gaining 2.9 percent. The A380 contract is the first in almost two years from a new customer after the introduction of the world's biggest passenger plane was delayed for 24 months by wiring problems.

Rolls-Royce gained three pence, or 0.6 percent, to 524 pence having earlier added 2.2 percent. The deal for the London- based company's Trent engines may be worth $5 billion, including maintenance work, it said.

Chicago-based Boeing was trading down 13 cents, or 0.1 percent, at $104.32 as of 11.52 a.m. in New York.

The aircraft ordered by British Airways today are needed to replace 20 aging Boeing 747s and 14 767s and to help the company compete with Virgin Atlantic, owned by UK billionaire Richard Branson, and business-only startups such as Silverjet Plc.

Virgin's passenger count rose by 700,000 to 5.1 million last year. British Airways added 634,000 customers in the 12 months through March for a total of 33.1m. Virgin has an 18 percent share of the London-US market, compared with 38.9 percent at its larger rival, Panmure Gordon & Co. said yesterday.

British Airways also has options to buy 18 more Dreamliners and seven more A380s, it said yesterday. The carrier has arranged for a group of banks to provide $1.5bn of debt-financing to cover all of the firm orders to the end of 2011.

"They need to keep up with rivals like Virgin, but they want to grow at rates that are suitable to them," said Gert Zonneveld, a London-based Panmure analyst with a "buy" recommendation on the stock. "With extra options, they'll have the ability to control their expansion."