A union representing aircraft mechanics at shipping giant UPS is again asking a federal board to release it from mediation, saying negotiations on a new contract are at an impasse.

Contract talks have been going on for nearly four years between Sandy Springs-based UPS and Teamsters Local 2727 representing the roughly 1,300 airline maintenance workers.

The mechanics are are covered by health insurance with no annual contribution and are concerned about losing some of their healthcare benefits.

UPS said it “continues to negotiate in good faith for a mutually agreeable contract,” and that negotiators have “moved closer on several economics issues” in talks, according to a written statement.

Teamsters Local 2727 last year took a strike authorization vote and early this year filed a request with the National Mediation Board for a release from federally-mediated negotiations. But the NMB sent them back to the bargaining table.

The union says since then, the company has refused to “offer reasonable proposals to come to a fair agreement, causing growing unrest and instability within the maintenance workforce as the busy holiday shipping season nears.”

UPS management said the union’s leaders “are turning to inflammatory and exaggerated public claims that misrepresent the Company’s offers.”

If the NMB grants a release from mediated talks, it could offer arbitration. If either side refuses to arbitrate, a 30-day “cooling off” period would start, after which mechanics could strike.

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