Robert Andrew Miles, 59, district manager of federal sales for Computer Communications Inc. in Alexandria, died Saturday at his Alexandria home. He had a heart ailment.

Mr. Miles began working in federal sales for computers about 20 years ago. Before joining COMPUTER communications about two years ago, he worked for several leading computer manufacturers, including the Burroughs Corp., Honeywell Inc. and Sperry Univac.

He was born in Troy, N.Y. He earned a bachelor's degree in business from the Virginia Southern College in Roanoke and lived in Roanoke before coming to this area in 1960.

A retired Air Force captain, Mr. Miles was an Army pilot during World War II and participated in the Normandy invasion. He also took part in the Berlin airlift and served in Korea during the Korean conflict.

His military decorations include the Distinguished Flying Cross and the Air Medal with four oak leave clusters.

Survivors include his wife, Jane Starz Miles, of Washington; a son, Robert W., of the home in Alexandria; a sister, Virginia M. Adams of Clinton, N.C., and a brother, Delmar, of Rochester, N.Y.

The family suggests that expressions of sympathy be in the form of contributions to the American Heart Association.