The International Association of Machinists union at Northwest Airlines filed suit against Delta Air Lines, arguing that Delta's launch of a seniority integration process for the union's members before union representation elections are held is unlawful.
The machinists union's lawsuit, filed Monday in U.S. District Court in Washington, follows a similar one filed late last month by the Association of Flight Attendants, which represents flight attendants from Northwest.
Now that Atlanta-based Delta has closed its merger with Eagan, Minn.-based Northwest, many employees at the combined carrier will likely vote on whether to unionize.
The work force from Northwest is highly unionized, while Delta's only large unionized group is its pilots.
The International Association of Machinists and Aerospace Workers represents more than 12,000 employees from Northwest, including baggage handlers, customer service agents, reservations agents and others.
The union argued in the suit that the move by Delta to start a seniority integration process amounts to unlawful interference with employees' rights to choose a union to represent them and bargain collectively.
The airline and the unions are taking positions on the seniority integration matter that could influence the outcome of the union representation vote, in part because the company's process for seniority integration could yield a different result from the union's method.
The union also argued that Delta's "demand" to start a seniority integration process before a union representation election is part of efforts to undermine the IAM's campaign to represent employees from both Northwest and Delta.
Delta spokesman Kent Landers said the company believes the position the machinists and flight attendants unions have taken is "wrong as a matter of law and does not serve the interests of our combined work groups. And, importantly, seniority integration is one of the top issues on our employees' minds and we are committed to resolving seniority and integration issues promptly."