J. C. Constanz, 64, vice president of federal affairs for Republic Airlines Inc. and a former chief of economic planning and programming for the old Civil Aeronautics Board, died May 20 at Arlington Hospital. He had a heart ailment.

Mr. Constanz began his career in aviation with Transcontinental and Western Airlines, a predecessor of Trans World Airlines (TWA), after earning a bachelor's degree from Culver-Stockton College in his native Canton, Mo.

He worked in Transcontinental's treasury department before transferring to the airline's route development office here in 1946.

As director of regulatory proceedings for TWA, he was in charge of planning for extension of international routes and represented TWA in bilateral negotiations with foreign governments on air transport agreements. He also was an adviser to the U.S. delegation in air transport consultations with foreign governments in Europe, North Africa and the Far East.

From 1956 to 1962, when he returned to the Washington area, Mr. Constantz was director of economics research for TWA in New York City.

In 1962, he was appointed chief of economic planning and programming for Civil Aeronautics Board.

Mr. Constanz became assistant to the president of North Central Airlines in 1978. When North Central merged with Southern Airlines last year to form Republic Airlines, he was appointed vice president of federal affairs for Republic.

An Arlington resident, he served as president of the Ashlawn, Kenmore and Washington-Lee Parent-Teachers Association and the Boulevard Manor Civic Association.

Survivors include his wife, the former Betty Powell, of Arlington; five sons, Jon, of Manassas, Joel, of Arlington, Jay, of St. Louis, Jed, of Boston, and Jeffrey, of Charlottesville, Va.; four brothers, Dr. Quinn H., of Cullowhee, N.C., George D., of St. Louis, Dr. Robert B., of San Francisco, and Donald A., of Loveland, Colo.; a sister, Ann English of Dallas, Tex., and a granddaughter.

The family suggests that expressions of sympathy be in the form of contributions to the Outdoor Education Association, 202 North Edgewood St., Arlington, 22201.