Contract negotiations between United Airlines and ground workers who are members of the International Association of Machinists and Aerospace Workers have recently resulted in a tentative labor agreement. The agreement is expected to include job protections, guards against outsourcing tasks, and leading wage rates, and it will cover tens of thousands of workers. The union will be putting the agreement to a vote to determine ratification or rejection of the offer. These are not the only contact negotiations occurring at United, as the airline company is currently engaged in labor talks with unions representing pilots and flight attendants as well.
See "Pilots, flight attendants, and ground workers all engaged in labor talks and contract negotiations with United Airlines", Noah Sheidlower, CNBC, March 29, 2023