David O. Cooper, 68, an official with the Federal Communications Commission for 30 years before retiring in 1971, died of cardiac arrest Oct. 2 in his Arlington home.

He worked in the FCC's Washington headquarters before becoming chief of a field division in Kansas City, Mo., in 1948. three years later he moved to New Mexico as supervisor of the CONELRAD program for the southwest United States.

CONELRAD (Control of Electromagnetic Radiation) was a government program operated from 1951 to 1963. The plan was to switch the frequencies of AM stations in case of war to prevent the stations' use as a navigation aid to enemy aircraft and missiles.

Mr. Cooper became CONELRAD supervisor for the eastern United States in New York from 1957 until returning to Washington in 1961. He was assistant chief of the FCC's frequency allocation and treaty division for 10 years before retiring.

He was a member of Trinity Presbyterian Church in Arlington.

Mr. Cooper was born in Akashi, Japan, where his parents were missionaries with the Free Methodist Church. He came to this country at an early age, graduated from high school in Cincinnati, and earned a bachelor's degree in electrical engineering at the School of Mines in Rapid City, S.D. He worked for RCA and a local power company in Indiana before moving to Washington.

Survivors include his wife, Mary, of the home in Arlington; a daughter, Andrea Compton, of Paris, Tex.; a son, John, of Miami, Fla.; a sister, Bernice Waddell, of Claremont, Calif.; a brother, Robert, of Jacksonville Beach, Fla., and two grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the Hospice of Northern Virginia, P.O. Box 1590, Arlington, Va., 22210.