The trade group said it would take the National Mediation Board to court for changing the way votes are counted in elections among workers attempting to form a union, the Memphis Commercial Appeal reported Tuesday.
The previous rule set by the National Mediation Board would count as a no vote a worker who did not take part in balloting.
On Monday, the board changed the rule, which had been in effect for 75 years. The new rule says a simple majority among those who vote would be enough to establish a union.
"The reality is nowhere else in the nation does your vote count without participating," said Shawn Fivecoat, an official with the Association of Flight Attendants.
ATA spokesman David Castelveter said: "We don't think the NMB has the authority to change the election process. We think the process they followed (in making the rule change) was legally deficient."