Joseph J. O'Connell Jr., 77, the first chairman of the National Transportation Safety Board who was remembered for the high standards he set in the early years of the agency, died of a heart attack July 13 at his home in Delray Beach, Fla.

President Lyndon B. Johnson appointed Mr. O'Connell head of the NTSB in 1967, when it was organized. The board is charged with determining the probable cause of major accidents involving aircraft, shipping, railroads and vehicles on highways.

Mr. O'Connell was named to the job after wide experience in law, government and transportation, having served as general counsel of the Treasury, chairman of the Civil Aeronautics Board and chairman of Lake Central Airlines. In his private law practice he specialized in aviation and transportation law.

This background enabled Mr. O'Connell to set the NTSB on the course that earned the reputation it enjoys today. He remained chairman of the agency until the Nixon administration took office in 1969.

Mr. O'Connell was born in Saranac Lake, N.Y. He graduated from the University of Vermont in 1926 and earned a law degree at Fordham University in 1930. He later was awarded an honorary law degree by Rider College.

He came to Washington in the mid-1930s and joined the Public Works Administration. From 1938 to 1947, he was at the Treasury Department. He was chairman of the Civil Aeronautics Board from 1948 to 1950 and then entered a private law practice.

In 1955, he was named chairman of Lake Central Airlines. From 1965 until he was appointed to the NTSB, he was a member of the law firm of Chapman and O'Connell. He returned there in 1969 and retired to Florida in 1971.

Survivors include his wife, Hazel, of Delray Beach, and two daughters, Margaret, of Washington, and Sheila, of New York City.