In the email, United said its contracts typically require vendors to abide by applicable local, state and federal laws. The airline wrote: "If the Policy becomes effective, and assuming it is validly issued, the vendors would be required to comply with the Policy or they would be in violation of their contracts with us."
The email came near the end of a 30-day public comment period on the Port Authority's order, which applies to workers at New York's three major airports. Some workers at Kennedy and LaGuardia airports have already received raises, according to Ana Maria Cruz, a spokeswoman for Local 32BJ of the Service Employees International Union.
Chicago-based United, which operates roughly three of every four flights at Newark, had criticized the increases in a February letter to the Port Authority, saying the order raised "significant legal issues." United said the wage increases might not be enforceable without legislative approval.
The airline also raised the possibility of antitrust issues since the Port Authority was "requiring airlines to act in concert to force wage raises on third party contractors."
A United spokesman declined to say Friday if the company would mount a legal challenge to the wage hikes. In United's email, the airline said the hikes would cost the company about $12 million a year.
In January, Port Authority executive director Patrick Foye sent a letter to United, JetBlue, Delta and American, ordering the pay hikes for low-wage workers, which also includes skycaps and ticketing agents. Many of these workers are employed by private companies that contract with the airlines for their services.
According to Foye, Delta and American agreed to the new rules. United and JetBlue expressed similar concerns regarding wage increases without legislative action.
Port Authority board members have said recently they support eventually expanding the wage hikes to contract workers at all the agency's facilities, which include bridges and tolls, the ports of New York and New Jersey, the World Trade Center site and the Port Authority Bus Terminal.
Irwin Carbajal, a cabin cleaner from Elizabeth who earns $8.25 per hour cleaning planes at Newark, said he is afraid to get sick or injured because he can't afford health insurance. The native of Peru lives with his father in a room at his uncle's house and does extra work for his uncle to help pay the rent.
"If you get injured, your whole monthly pay could go for your health bills," he said.
Karen Boroff, a professor of management and dean emeritus at Seton Hall University's Stillman School of Business, said United and JetBlue could have valid legal challenges to the hikes but may conclude the risks outweigh the benefits. She also questioned the effects of the wage increases.
"These jobs are low-skilled. Giving them another buck isn't going to raise their skill level," she said. "I'd rather have these people get vouchers for education or for technical training."
Some West Coast airports have raised minimum wages for workers in recent years. But a judge decided a $15-per-hour minimum wage approved last year by the city of SeaTac, which surrounds Seattle-Tacoma International Airport in Washington, does not apply to airport workers because the airport is operated by the Port of Seattle.