Robert Frailey, the athletic director at American University since 1964, surprised his colleagues at an athletic department staff meeting yesterday by announcing his resignation, which will go into effect May 1, 1987.

According to Craig Tartasky, American's director of athletic relations, the 10 a.m. meeting followed a set agenda until the last item, when Frailey told the gathering: "Just so you don't hear it first from anyone else, I'm resigning."

Tartasky said, "It was a shock. There were some chins hitting the floor. The man is AU athletics."

Frailey, who was not available to comment yesterday, was quoted in a press release issued by American as saying: "I plan to be around to help smooth the transition for my successor. I felt it was time to step down and let someone with a fresh, innovative approach lead our program into a very promising time ahead."

Of the search for a successor, Tartasky said: "Donald Triezenberg vice president for development will probably set it up and establish the criteria. We don't know any of the who, what or where.

"I wouldn't be surprised if the search was a nationwide one. But it hasn't been decided yet, whether it will be an in-house search, a national one or a combination."

Triezenberg is on vacation and could not be reached for comment. He said in the press release, " Frailey is irreplaceable. We hope he will maintain contact with and support for the sports program he has done so much to build."

American is in the process of building the Adnan Khashoggi Sports and Convocation Center on campus, scheduled to be completed in time for the 1987-88 basketball season. "We'll have a new building and a new direction," said Tartasky. "I guess Frailey just felt the time was right to retire. He really didn't give any reasons. But he's doing it in a way so we won't lose continuity."

Frailey, 61, has been associated with sports at American for 38 years. He graduated from the school in 1949 and became the Eagles' swimming coach. He also coached the tennis and golf teams for a number of years, and in 15 seasons as a head coach he never had a losing record.

Frailey was appointed director of athletics in 1964 and two years later upgraded the school's athletic programs to the Division I level. He was instrumental in the creation of the Colonial Athletic Association and designed the CAA logo. He has served on the NCAA Executive Committee and is the longest-tenured faculty member in American's College of Arts and Sciences.