Delta Air Lines Inc. says a federal board has upheld results from an election that blocked a union from representing its flight attendants.
Delta said late Friday that the National Mediation Board rejected claims by the Association of Flight Attendants that the company interfered in the representation election last year.
The union criticized the ruling, saying Delta unfairly pressured flight attendants to vote against representation and, in some case, supervisors made threats against union supporters.
"This is not democracy, not in outcome nor process," the union said in a statement.
Delta said the ruling would let flight attendants from Delta and the old Northwest move ahead as a combined group. Vice president Joanne Smith said Delta would immediately begin raising pay for Northwest flight attendants to Delta's hourly rates.
The airline still faces claims of interference in union elections for customer service, cargo, reservation sales and other employees. It said it hoped for a similar ruling in those cases.
Pilots were the only large group that was unionized at Delta when it bought Northwest. The combination of Delta and Northwest triggered elections to see whether Northwest unions would represent workers in the combined groups.
The Association of Flight Attendants fell about 300 votes short out of more than 18,000 cast in its bid to represent the Delta employees.
Delta is the nation's second-largest airline company behind United Continental Holdings Inc.
Delta shares rose 8 cents to close at $7.36.