Newly signed contracts between United Airlines (UAL) - Get Report and its largest union have an unprecedented effect: They bring back work that had been outsourced and they protect thousands of other jobs from being outsourced in the foreseeable future.

Under the contracts, which are scheduled to be signed Monday, about 400 to 500 fleet service and passenger service agent jobs for United Express at Los Angeles International and San Francisco International airports were brought under the jurisdiction of the International Association of Machinists, which represents 30,000 United workers.

"We never had this before," said Mike Klemm, president of IAM District 141. "The unprecedented thing is that no {major airline} contract has ever been able to protect regional flying until now."

During the tumultuous early years of the 21st century, when the U.S. airline industry lost tens of billions of dollars and nearly every major legacy airline experienced bankruptcies, union protection was widely eroded. The United/IAM contracts reverse that trend.

Besides bringing in the regional flying, the contracts indefinitely extend union protections for several other groups.

They include 8,500 fleet service and passenger service agent jobs at 23 airports, such as Boston Logan and Washington National, generally major airports where United isn't a dominant carrier. Under previous agreements, that work was protected until 2019.

Also, union protections for the 10,000 United Express jobs at United's hub airports, which had been scheduled for review in 2019, were extended indefinitely. United mainline work at hub airports has always been protected but that wasn't the case for express work.

Raises, a bonus and improved pension benefits were also part of the contract deals.

All of the 30,000 IAM workers at United will receive 18.4% raises effective Nov. 15, with an additional 30% through 2021. The union represents seven United work groups, primarily including 13,000 to 14,000 workers in each of two categories: fleet service and passenger agents. In each of the seven groups, the salaries will be industry-leading, the union said.

CEO Oscar Munoz didn't participate directly in the talks, Klemm said, "but at the end he was a phone call away on several hot topic issues" including salary and the extended union protections. Munoz was consulted in both cases, Klemm said.

Regarding United's announcement that it had reached a deal with two hedge funds to add three new directors and make other changes to its board, Klemm declared: "We have an improving relationship with United. We were able to secure industry leading contracts -- that's a reflection of the improving relationship.

"We hope the new people on the board aren't going to poison that relationship," he said.

The contract also includes a $100 million lump sum payment that will entitle every one of the 30,000 workers to a one-time payment of $200 for each year of service.

One other major benefit in the contract was a 25% increase in benefits that will be paid out under the IAM's defined benefit pension plan. IAM is the only United union with a defined benefit pension plan.

About 11,500 former Continental flight attendants are covered by a defined benefit pension plan negotiated by the IAM, but the group is now represented by the Association of Flight Attendants, which is among the unions that hasn't signed a new contract or an extension since Munoz took over as CEO in September.

Besides fleet workers and agents, both at the airports and in reservations, the IAM's seven contracts cover storekeepers, maintenance instructors, fleet technical instructors, and related and security officer classifications.

At San Francisco International Airport, United Express airport agents had been covered by the IAM contract, but United Express fleet service workers weren't. At LAX, neither group had union representation.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.