United Airlines has informed union employees at 28 airports that their work may be contracted out.

“We need to ensure our costs are competitive and we are considering transitioning some of our operations at select airports to an outside vendor,” United spokesman Luke Punzenberger confirmed.

Workers represented by the International Association of Machinists and Aerospace Workers District Lodge 141 at such airports as Hartsfield-Jackson in Atlanta, Bradley International in Hartford, Conn., San Antonio International, St. Louis and Kansas City were given notice Monday morning that their jobs are on the line as the airline reviews costs.

“As many of you know, our major competitors in these locations — like Delta and American — have workforce arrangements, including market competitive sourcing, that allow them to operate in these stations at significantly lower costs that are more in line with local markets,” United Senior Vice President of Operations Jon Roitman said in a letter to affected employees Monday.

United reported third-quarter 2014 net income of $1.1 billion — an increase of 99 percent over third quarter 2013, and its highest-ever quarterly profit.

This is the latest in a series of maneuvers by the airline to control costs by cutting labor expenses. United outsourced nearly 500 jobs to outside vendors in 2013 and more than 600 jobs at 12 other U.S. airports in the fall of 2014.

The jobs that have the potential to be affected in this latest move fall into the category of “airport operations,” which includes baggage-handing ramp workers and inside customer service agents, among others, depending on the airport.

The most recent contract between IAM and the airline requires that the two groups meet to attempt to negotiate terms to keep the work with the union — a provision that was negotiated in the 2013 contract that merged workforces of United and Continental Airlines, said IAM 141 president Rich Delaney.

“Job security was the overwhelming issue of those talks due to the histories of both carriers,” Delaney said via e-mail. “Prior to reaching the agreement with United, less than 20 percent of the total unionized population had employment protection.”

Delaney said that percentage increased to 90 percent by requiring the airline negotiate work agreements on a per-airport basis.

“The purpose and goal of these meetings is to look at each station individually and look for alternatives that will allow our members to continue to work in their home stations and maintain the level of wages and benefits they deserve,” Delaney said. “If that is not possible, other security and seniority provisions will be implemented to allow our members to continue to work for United Airlines in other locations, if they choose.”

IAM members took to social media Monday to express concern. Among them, IAM district member Tim Nelson, in Chicago, who expressed dismay over the news.

“When United was in bankruptcy, they didn’t outsource all these jobs. Now, making billions of dollars off the backs of those workers who helped save the airline, the new management decided to outsource their family-rearing jobs while giving themselves pay raises,” he said.

There are about 2,000 United airport operations workers nationwide who could be impacted by the potential outsourcing, some of whom could transfer to other airports, including Denver International Airport, according to the airline.

United has recently been under scrutiny at DIA amid passenger reports of lost luggage, delayed flights and a chaotic baggage-claim area. Passengers promised home delivery for misplaced luggage have also waited up to a week to receive their bags.

The airline has pointed fingers at holiday travel, weather, and new United Express baggage-handling vendor Simplicity Ground Services for the issues. The contract at DIA had been held by SkyWest Airlines for nine years.

But the problem can’t be pinned solely on Simplicity. Luggage handling at DIA is a duty shared by Simplicity and United Airlines employees, depending on the flight and bag destination.

United mainline flights are handled by United’s IAM-represented workers.

Simplicity Ground Services on Dec. 4 took over the below-wing baggage service contract for the majority of United Express daily regional flights at DIA.

United workers also took over many bag transfer responsibilities from SkyWest on Oct. 19, a change that added about 260 to 300 flights per day to United workers’ duties with no additional hands on deck, per Denver-based United ramp employees who asked not to be identified because of fears of disciplinary action, including termination.

Neither the airline nor Simplicity would comment on whether or not additional workers would be added in Denver to help handle the workload.

Delaney, however, confirmed Monday that the airline has been adding IAM workers to help with United mainline flights.

“The issue in DEN is that work was insourced to United employees, not outsourced. We have met with United to resolve the manpower issues this insourcing created,” he wrote. “As a result, members have been upgraded from part-time to full-time status and United has begun hiring employees in classifications we represent.”

Simplicity spokesman Mickey Mandelbaum said the company pays its workers $12 per hour with no flight perks. SkyWest-contracted employees were paid $10.40 per hour to start, with raises up to $20 per hour, and flight benefits on United.

Former SkyWest employees are not surprised that things have fallen apart.

“When you add up the hourly wage and the free-flights perks, I guess that was enough for United to make the switch,” said former SkyWest ramp employee Daniel Joseph. “Unfortunately for United, it pays to have someone with experience dealing with customer bags. When customers have so many flight options to choose from in today’s age, you can’t give them a valid reason to fly someone else.”

Delaney said he wishes United would have acted more quickly in Denver, but that he feels the steps the airline is taking now will “go a long way” to fixing the situation.

The baggage trouble at DIA is taking its toll on United employees in the meantime.

“We used to enjoy being in uniform, taking pride in our jobs and this company. Now when we wear our uniforms, we hear people tell us how we lost their bag last week,” said one employee who asked not to be identified because speaking to the media can result in being fired. “It’s not our fault that the company can’t staff us enough.”

The first meeting between the airline and the union to discuss future outsourcing is scheduled for Tuesday, with additional meetings to be held through the week.

Laura Keeney: 303-954-1337, lkeeney@denverpost.com or twitter.com/LauraKeeney