Francis H. McAdams, 69, one of the original members of the National Transportation Safety Board and a longtime advocate of improved training for airline pilots, died of cardiac arrest Dec. 11 at Sibley Memorial Hospital. He had arteriosclerosis and was stricken after jogging on the American University track.

Mr. McAdams had been a safety counselor for the Air Transport Association of America since his retirement from the safety board in December 1983.

The board is best known for its investigations of highly publicized airline accidents. Mr. McAdams was the board member in charge of the investigation here in January 1982 after an Air Florida jet taking off from National Airport crashed into the 14th Street bridge and killed 78 people.

The safety board was organized in 1967 from the old Civil Aeronautics Board's aviation accident investigation office. Mr. McAdams was appointed by President Lyndon B. Johnson and subsequently reappointed by Presidents Nixon, Ford and Carter. He unsuccessfully sought reappointment from President Reagan.

One of his great disappointments, he said in an interview two years ago, was that he was never named chairman of the board.

Mr. McAdams was known as "the great dissenter" because of his proclivity for writing dissenting opinions when he disagreed with the five-member board's findings of probable cause in transportation accidents.

He said the dissent of which he is proudest is one that ultimately reshaped the board's majority position. It concerned the midair collision over San Diego in 1978 between a Pacific Southwest Airlines jetliner and a small private plane. A total of 144 people died.

The board initially ruled that the probable cause "was the failure of the flight crew" of the jetliner to keep itself clear of the smaller plane. Mr. McAdams contended that "inadequacies of the air traffic control system" were the probable cause because controllers "had the capability of providing either vertical or lateral separation" between the planes, but failed to do so.

In August 1982, after persistent lobbying by Mr. McAdams, the board changed the probable cause to show that "air traffic control procedures played an equal role with that of the flight crew . . . . "

Mr. McAdams was a native of Brooklyn, N.Y., and a graduate of Georgetown University and its law school. His safety board experience was the culmination of an adult lifetime in aviation. He received a certificate as a commercial pilot in 1939 and flew with the Navy in World War II as a pilot and was executive officer of an aircraft-carrier fighter squadron.

He became an aircraft accident investigator with the CAB in 1946. He was a regulatory attorney with the CAB, and then with Capital Airlines, which was merged into United Airlines.

In the 1983 interview, Mr. McAdams said the increasing complexity of modern aircraft demanded improved crew training. "If something goes wrong, it's back to the basics," he said, and he wondered if today's computer-monitoring pilots had the basics. "If properly trained, a pilot should be able to get it back on the ground safely," he said.

His wife, Katherine Egan McAdams, died in 1983. Survivors include two sons, Michael and Peter, both of Washington; two daughters, Hope McAdams Frank of Darien, Conn., and Wootie McAdams of Portland, Ore., and one grandchild