US Airways Group Inc has ordered 20 Airbus A350 planes honouring its promise to buy the fuel-efficient aircraft aimed at trans-Atlantic flights as part of a financing deal for the airline’s acquisition by America West Airlines.

Trading in United Airlines’ shares was halted in the US today after they plunged 59%, a day after the world’s second-largest carrier lost its request for government loan backing it said was needed to keep it out of bankruptcy.