Northrop Grumman Corp. and the maker of Airbus planes won a multibillion-dollar Air Force contract to build 179 tankers used to refuel military aircraft mid-flight, a congressional staffer familiar with the award said Friday.

The staffer, who learned of the award from a Northrop Grumman employee, spoke on condition of anonymity.

The selection of Los Angeles-based Northrop Grumman and European Aeronautic Defence and Space Co. comes as a surprise to Wall Street and major blow to Boeing Co.

Chicago-based Boeing has been supplying refueling tankers to the Air Force for nearly 50 years and had been expected to win the deal.

The contract will be worth between $30 billion and $40 billion over 10 to 15 years. It is the first of three awards worth up to $100 billion over 30 years to replace the entire Air Force fleet of nearly 600 tankers.