Alexander Butterfield had a distinguished career long before he burst onto front pages in 1973 with a startling revelation during the Watergate investigation. He was a decorated Air Force pilot in 1969 when President Richard Nixon invited him to join the White House staff, and he was head of the Federal Aviation Administration when he testified before the Senate regarding the 1972 break-in at Democratic Party headquarters in the Watergate building. It was his unwitting testimony about the secret taping operation in the White House that eventually sealed Nixon's fate. Butterfield was born in 1926 in Pensacola, where his father was stationed while in the Navy. He spent much of his youth in California and Virginia, then briefly lived in Pensacola again. Young Butterfield opted for a military career, earning a commission as a second lieutenant in the Air Force in 1949. He advanced steadily to colonel. In the meantime, he earned a bachelor's degree from the University of Maryland. From 1957 to 1959, he was an assistant professor at the Air Force Academy, then went on to command all U.S. low- and medium-level air reconnaissance operations in Southeast Asia from 1962 to 1964. In 1969, when he retired from the military, he joined Nixon's White House staff and, for the next 4{ years, he was in his words, "as physically close to Nixon as anyone could get." Later Nixon appointed Butterfield to head the FAA, and he was in that job when he was summoned by a special Senate committee to testify in the Watergate hearings. Butterfield, who was untouched by the scandal, thought that presidential aide H. R. Haldeman already had told investigators about Nixon's secret taping operation and that he was merely being asked to corroborate the story. His testimony was the beginning of the end of Nixon's Washington career _ and his own. Nixon cut off all communication with him, and when Gerald Ford became president, he asked Butterfield to resign from the FAA. More than 20 years later, Butterfield finds himself reliving those Nixon years. Recently he served as a technical adviser to Oliver Stone for his new movie, Nixon. And Butterfield is continuing work on a book about Nixon, which is expected to be published by Little Brown in 1997. "Almost everyone else involved in Watergate has written at least one book," he said. "I haven't, and I was as close to Nixon as any living human being. I sat outside the president's office and ran his day. My job was to see that his schedule went as planned." Butterfield, who also served as Cabinet secretary, said his book will be sprinkled with Nixon and Haldeman anecdotes. "I don't try to solve the Watergate mysteries," he said. "I'm just writing about my White House experiences." His White House experiences were the expertise he brought to the set of Nixon, which is expected to be released late this year or early in 1996. "I was hired for two reasons," he said. "One was to help the actors to the extent that they needed help. For example, Anthony Hopkins, who plays the title role, had seen a lot of Nixon film. But I could confirm for him what Nixon did and didn't do, such things as his distinctive gestures. "I could tell them who swore and who didn't swear (Nixon and Haldeman were very profane, John Ehrlichman and Henry Kissinger were not), who put their feet up on the desk, how many White House police were outside the door." Butterfield, who worked on the set for nearly three months, was impressed with the "tremendous pains they went to and the effort they put out to make a set authentic." "When I was on the Oval Office set, there was no way I could not believe I was in Washington," he said. "There were the same chairs, the same lamps, the Eisenhower painting over the fireplace. And the scenery outside was Washington. I had to walk out of there to convince myself I was on a sound stage in Culver City, Calif." Butterfield said Nixon is not a movie about Watergate. Rather, he said, it is a film about Nixon's complex personality. "He was the strangest guy I ever met, bordering on being paranoid. And the film looks at some of the things that might have caused this." The filmmakers researched Nixon's childhood and early life, he said. "I think that people who love and adore Nixon are not going to like the film," he said. "But people who didn't like Nixon will say, "I'll be damned; I understand him a little better now.' They'll come away a little more empathetic, but they still won't like Nixon." Butterfield views Hopkins' performance as superb. "When I was not in the room and heard him, I could not believe it wasn't Richard Nixon." He also said Paul Sorvino, as Henry Kissinger, and Joan Allen, as Pat Nixon, do superlative jobs. But he saves his highest praise for Stone. "The actors and actresses and all the other people on the set love this guy," Butterfield said. "He's got a nice sense of humor, he's very considerate of the cast and crew, he never screams. And he's a fast shooter. The average film takes 75 to 80 days to shoot; this film is longer than average and was scheduled for 62 days, and he finished two days early." But he says Stone took some liberties. "He has Nixon getting up and pacing around; he never did that," Butterfield said. But Stone explained he couldn't just let him sit at the desk or audiences would fall sleep. And he has people riding with Nixon in the presidential limousine even though only Secret Service personnel would have held those seats. But he said that change was necessary for dialogue purposes. The set took Butterfield back to his days with Nixon, but two decades ago, he was persona non grata in White House circles. After resigning from the FAA, Butterfield became chief executive officer of a San Francisco aviation company. Then he joined California Life Corp., a Los Angeles financial holding company, as its president. Later he became associated with a consulting firm, and a couple of years later formed his own management consulting company, which he ran for 12 years. He says he "totally retired" Dec. 31, 1994, and now lives in San Diego. He is 69. He and his wife have been divorced for 11 years. "But we remain very close," he said. "We're good friends." They have a son, two daughters and seven grandchildren. Although Butterfield said his book won't break new ground on Watergate, he said there is one thing of which he remains certain: "Nixon knew in advance of the plans for that break-in at Democratic Party headquarters. There's absolutely no question about that."