Secor D. Browne, 69, who served as chairman of the Civil Aeronautics Board from 1969 to 1973, and was head of his own Washington aviation consulting concern since that time, died of cancer March 23 at a hospital in Boston.

He joined the government as the assistant secretary of transportation for research and technology in 1969 and became CAB chairman later that year. He was head of Secor Browne Associates Inc. from 1973 until his death. He had been living in Charlestown, R.I., for the past month.

Mr. Browne was a native of Chicago. An aeronautical engineer by training, he was a 1938 graduate of Harvard University. He served with the Army Air Forces in the Mediterranean theater during World War II. After the war, he held a variety of posts involving aeronautical engineering. He was board chairman and president of Browne & Shaw, a Waltham, Mass., consulting firm, for 14 years before moving here in 1969.

He was chairman of the Flight Safety Foundation. He was a member of St. John's Episcopal Church at Lafayette Park, the National Aeronautics Club and the Metropolitan Club, all in Washington.

Survivors include his wife, the former Constance Ely of Charlestown; eight children, a brother, a sister, and six grandchildren.