The US Airways website clearly states the prices for food on domestic flights. However, for Transatlantic, no charge is mentioned. The following statements were taken from "In The Air". The food serveed can be pretty bad at times so I'd still take a few back up snacks.

"Transatlantic Economy Class passengers on flights between the U.S. and Europe have a choice of hearty entrées.

Rotated monthly, the upgraded menu consists of a choice between two hot entrées, refreshing salads, breads and desserts. We focus on keeping the menu fresh to ensure that a healthy variety of options is available for frequent flyers."

Meals
Flights to Europe
Choice of dinner entrées with a fresh green salad, hearty multi-grain roll and all-American-style dessert.
Morning arrival service features a different Danish each month, including apple, cream cheese, raspberry and apricot.

Flights to the U.S.
Choice of lunch entrées accompanied by a salad, a European-style roll and dessert.
Arrival service features fresh, hearty sandwiches.