Amid growing complaints about overtime, stress and obsolete equipment, the nation's air traffic controllers voted overwhelmingly yesterday to organize a new union -- six years after 11,400 controllers were fired for striking over many of the same issues.

After 30 days of balloting, the controllers voted by better than 2 to 1 to accept the National Air Traffic Controllers Association (NATCA) as their new union.

Labor leaders viewed the vote as a symbol as important for labor's rebirth as the 1981 showdown with President Reagan was for its decline.

"This election is a turning point and the start of a new trend," said C.E. DeFries, president of the National Marine Engineers Beneficial Association, which helped NATCA start up.

The union vote was announced the same day that the Federal Aviation Administration unveiled further refinements to control peak summer season traffic -- refinements that were applauded by the National Transportation Safety Board. The NTSB, which has pushed the FAA to reduce air traffic this summer, said it was "encouraged" to see the FAA searching for additional solutions to airspace problems.

Overcrowded sectors have become a sore point with controllers in major facilities, who complained to the FAA that they were being asked to handle too much traffic.

The union vote -- 7,494 to 3,274 -- was the first time controllers have tried to organize a new union since 11,400 of 16,500 controllers were fired by Reagan in 1981 for striking illegally. That confrontation destroyed the Professional Air Traffic Controllers Organization (PATCO), which went bankrupt in 1982.

After the strike, the FAA struggled to rebuild the air traffic control system. But the rebuilding has been too slow, controllers argue, and morale eroded from an almost euphoric "can do" feeling immediately after the strike to frustration and discontent today.

Ironically, said New York area controller David Pearson, the FAA could have kept the union out; the mood among many of the controllers after the strike was anti-union, and many denounced the strike as a mistake.

"I think the FAA did have the opportunity," Pearson said, but added that the mood began to change about three years ago, when hiring lagged and controllers began to wear down from overwork.

"The troubles, the issues, the equipment are the same," he said. "There are less controllers and more traffic."

Controllers at some major facilities are still working six-day weeks. Controllers say FAA's attempt to create employe-relations committees failed as a remedy, in part because the committees did not deal with what the controllers thought were significant issues.

Despite a bitterness that runs most strongly among controllers who have moved from anti- to pro-union, NATCA's organizers say they do not want to repeat the mistakes that led to the 1981 confrontation. John F. Thornton, NATCA's national organizer, said the union's constitution contains a "no-strike" clause and other safeguards have been written into the bylaws to prevent "a small minority" from taking over the union -- a reference to the leadership of PATCO who encouraged the strike.

Bob Buckhorn, an FAA spokesman, said the agency intends to work with the new union, and pointed out that the FAA deals with 10 other unions.

"The individuals who comprise the controller work force are a most important part of the nation's air traffic control system," the agency said in a statement. "The FAA remains committed to building an organizational culture which nurtures achievement of people's aspirations and is prepared to work with NATCA to achieve these goals."

The FAA announced yesterday it began a new program June 4 to spread out flights traversing oversaturated "sectors" of airspace. Jack Ryan, the FAA's director of operations, declined to call the effort a reduction, but said the number of flights flying through various crowded sectors would be reduced. He said the changes will mean more delays at airports.

"We are lessening the number of planes," Ryan said. "We are doing that by delaying on the ground."

Ryan said the FAA began slowing the number of planes flying through overcrowded sectors around Chicago's O'Hare International Airport and has expanded that effort to airports in Atlanta, Detroit, Newark and San Francisco.

During a test of the new program, Ryan said, there were anywhere from 118 to 295 more flight delays daily than would have otherwise occurred.

About 125, or one-fifth of the country's 652 "sectors" of airspace, have been identified by the FAA as having the potential for becoming oversaturated with planes during the summer season.