PRESTWICK could be in for a double boost following the announcement of one of the largest aircraft orders in commercial aviation history.

US Airways has announced that it wants to buy up to 400 Airbus aircraft over a three-year period and the order is worth an estimated $24bn.

As well as the possibility of spin-off work for the British Aerospace plant at Prestwick, the neighbouring Caledonian aero engine overhaul plant also stands to benefit.

British Aerospace has a 20% stake in Airbus Industrie and carries out a wide range of sub-assembly work for the Airbus family of planes at its Ayrshire facility.

Prestwick has been hit by a wave of job losses in recent years, the worst when the company announced it could no longer sustain losses on its Jetstream aircraft and closed the production line.

Almost 350 jobs were lost and work has been going on behind the scenes, with the backing of local MPs, councils, trade unions and the Scottish Office, to secure further work for those remaining at a plant which once employed almost 2000.

Caledonian was recently taken over by the global company GE which, in a joint venture with Sncema of France, will provide the engines for the US Airways planes.

The power units are expected to be CFM56, an engine for which the Prestwick plant is widely considered to be the world leader in maintenance and overhaul.

Mr John Horsburgh, managing director of the Prtestwick plant, said: ''It is too early to speculate on what direct benefit this order will have, but any order of this size is good news for the planemakers and for our parent company which will be involved in the engine production.''

US Airways issued a statement in Bonn yesterday which indicated that it has placed firm orders for 124 aircraft and had options on a further 276.

The orders will be phased in from late next year and into the year 2000 and involve single aisle aircraft ranging from the 150-seat Airbus A320 to its 185-seater stablemate the A321.

The airline has also set the hares running in the industry by announcing that it is considering a large order for wide-bodied aircraft - with its eyes set on either the Airbus A330 favoured by Virgin and Aer Lingus or the Boeing 777 in service with United and British Airways among others.

As well as expanding its hub at Philadelphia, with a $300m new terminal planned, the airline is in talks with transport authorities with a view to expanding its route network including the introduction of its seventh European destination at Milan.

Airbus Industrie was formed by BAe, Aerospatiale of France, Deutsche Airbus and CASA of Spain