Retired Army Col. Halvor T. Darracott, 70, whose 24-year military career was in the Signal Corps and who later worked as a civilian in communications for the Department of the Army, died of cardiac arrest Wednesday at his home in Falls Church.

After retiring from military service in 1962, he became a civilian employee of the Department of the Army, retiring for a second time in 1979 as chief communications and controls system officer at the Systems Development Headquarters, Development and Readiness Command here.

Col. Darracott was born in Wichita Falls, Tex. He graduated from Drury College in Springfield, Mo. and later earned a master's degree in physics from the University of Arkansas. He was commissioned in the Army in 1938.

His assignments had included battalion commander in the Army's 7th Division in Germany after World War II. He also had served in the office of the Chief Signal Officer in Washington, as deputy signal officer for the Military District of Washington, and as chief of the electronics branch in the Federal Aviation Administration's Experimental Center at Atlantic City. He worked for the Army Materiel Command as a civilian.

Col. Darracott was a fellow of the Washington Academy of Sciences. Other professional organizations in which he was active were the Institute of Electrical and Electronics Engineers, the American Physicists Society, the Washington Operational Research Council, the American Forces Communications and Electronics Association, the American Academy of Political and Social Scientists and the American Academy of Arts and Sciences.

He was a former president of the Kiwanis Club of Falls Church and a life-member of Kiwanis International. A 32nd degree Mason, he belonged to Kena Temple of the Shrine and the Shrine Greeters. He was serving his second term on the board of directors of the Mental Health Association of Northern Virginia. He had served on the vestry of St. Paul's Episcopal Church in Bailey's Cross Roads.

He is survived by his wife of 41 years, the former Margaret Jane Mitchell, of Falls Church; three children, Hattiejane Darricott of Beirut, Lebanon, William Michael of Gaithersburg and James Patrick, of Falls Church; three sisters, Alyse Link of Jefferson City, Mo., Frankye Prigg of Scottsdale, Ariz., and Mary Stultz of Reynoldsburg, Ohio, and a grandchild.