United Airlines Holdings has reached tentative agreements with the International Association of Machinists and Aerospace Workers (IAM) for providing improved wages to its nearly 30,000 ground workers, the union said Wednesday.

The detailed terms of the two-year contracts were not disclosed, but the union said it offers “industry-best” wage rates, better job security, insourcing of five previously outsourced locations and prohibiting outsourcing at 17 additional U.S. locations.

The pacts come as part of airlines’ efforts to retain workforce with attractive pay after a faster-than-expected rebound in the U.S. travel demand following the COVID-19 pandemic, which recorded steep job cuts in the industry.

IAM District 141 members covered by the tentative agreements would receive more details, the union said in a statement, adding that a ratification vote would be shortly scheduled.

The agreements cover seven different work classifications at the carrier, including fleet service workers, passenger service workers, storekeepers, central load planners, maintenance instructors, fleet technical instructors and security officers.

United is also separately locked in negotiations with its pilots over a new contract, with U.S. carriers under pressure to better Delta Air Lines’ pilot deal, which provided for a 34% cumulative pay increase and other benefits.