The flight attendant unions representing cabin crew members at Frontier Airlines, JetBlue Airways, and Spirit Airlines are backing a merger of Frontier and Spirit, or at least opposing JetBlue’s hostile takeover attempt of Spirit.

The Association of Flight Attendants-CWA (AFA), which represents flight attendants at Frontier and Spirit, said May 17 that it had reached a merger transition agreement with Frontier. The agreement would oversee the integration of cabin crew groups at Frontier and Spirit if the merger goes ahead.

“We are thrilled to announce our support for the merger of Spirit and Frontier Airlines after reaching a transition agreement that protects flight attendant jobs,” AFA International President Sara Nelson said. “We support the necessary regulatory approvals that will improve competition, increase consumer options and experience, and maintain and grow good union jobs.”

On Wednesday, the Transport Workers Union (TWU), which represents flight attendants at JetBlue, came out firmly against the New York-based airline’s hostile takeover attempt. “After thoughtfully considering the impact that a JetBlue acquisition of Spirit Airlines would have on customers and our workforce, the TWU fully opposes JetBlue’s proposed hostile takeover. JetBlue has proven itself to be an abusive employer by disregarding the well-being of its workforce, and refusing to abide by its existing union contracts,” TWU International President John Samuelson said.

Spirit shareholders will decide the fate of the airline. They are scheduled to vote on a combination with Frontier on June 10, which the Spirit board supports and JetBlue opposes through a separate tender offer.

Tags: frontier airlines, mergers and acquisitions, spirit airlines