ATLANTA — Delta Air Lines Inc. flight attendants have again failed to get the necessary votes to form a union.

The Association of Flight Attendants-CWA said in a statement Wednesday that not enough of the eligible flight attendants voted, and therefore the results, despite showing solid support from those people who did vote, did not meet the certification requirements of the National Mediation Board.

Federal rules require a majority turnout by those eligible to vote.

There were only 5,375 total votes cast. National Mediation Board rules required 6,691 ballots to be cast for the election to count. There were 13,380 Delta flight attendants eligible to vote.

Of those flight attendants who did vote, 5,306 voted in favor of forming a union.

A similar effort in late 2001 was rejected in election results announced on Feb. 1, 2002.

Delta flight attendants could get another shot at unionization after the completion of the carrier's acquisition of Eagan, Minn.-based Northwest Airlines Corp.

Northwest's 8,000 flight attendants are members of the AFA-CWA. Federal rules call for an automatic union election if at least 35 percent of the combined group is already represented by a union, which it will be in this case. Northwest flight attendants would still be covered by the union after the combination at least until another election.

"Delta flight attendants faced an aggressive campaign from management, and almost a majority of them were able to stand up," AFA-CWA spokeswoman Corey Caldwell said of the results announced Wednesday.

Kevin Griffin, the head of the Northwest branch of the Association of Flight Attendants, called the vote "disappointing," but said he wasn't surprised.

"They did have a heck of an uphill battle with Delta management, with all the anti-union propaganda," Griffin said.

But Joanne Smith, senior vice president of Delta's in-flight service division, said it was the union that was spreading misinformation, and all Delta tried to do was make sure its flight attendants had the facts before deciding whether to participate in the election.

"This was one of the biggest decisions our flight attendants faced in their careers at Delta," Smith said.

She added, "We've said all along, we respected their right to choose."

Delta's pilots remains the only major work group at the Atlanta-based carrier to be members of a union.

More than 55,000 flight attendants at 20 airlines are members of the AFA-CWA. The AFA is part of the 700,000-member Communications Workers of America.

AP Business Writer Joshua Freed contributed to this report from Minneapolis.