CHARLOTTE, N.C. ( TheStreet) -- Pilots at US Airways ( LCC) have mounted a campaign to oppose the carrier's slot swap with Delta ( DAL).

US Airways and Delta announced in August that the former carrier would trade slots at New York's LaGuardia Airport for slots at Washington Reagan National and Tokyo Narita. It also traded a Rio route authority for an unrestricted Brazil route authority.

The deal requires approval by the antitrust division of the U.S. Justice Department. The U.S. Airline Pilots Association, which represents US Airways pilots, said Monday it will seek a full investigation.

"We are extremely concerned about the market concentration that this transaction would create," said USAPA President Mike Cleary, in a letter to the department. "These conditions raise the prospect of much higher fares and, if history repeats itself, a reduction in services to smaller communities." Additionally, Cleary wrote, many of the airline's New York-based employees will lose their jobs.

Last week, about 70 pilots and 50 flight attendants picketed at the Massachusetts State House to protest the closing of US Airways' Boston crew base, part of the airline's continuing effort to eliminate unprofitable flying. The Massachusetts congressional delegation, including Sen. John Kerry, has sent the airline a letter urging that it reconsider its decision.

US Airways spokeswoman Michelle Mohr said US Airways lost about $800 million in 2008 and will lose more this year and "we have to make decisions that will return the airline to profitability." She said the Justice Department has been investigating the slot swap since shortly after it was announced in August. Since then, she said, "We have made two filings, submitted hundreds of thousands of documents and answered every question DOJ has asked.

"We are confident that the transaction presents no antitrust issues," Mohr said.

Delta spokesman Kent Landers said the transaction has broad support. Nearly 10,000 Delta customers and employees have voiced support to the departments of Justice and Transportation, as have a variety of New York officials including two senators, 20 members of Congress, New York state Governor David Paterson and New York City Mayor Michael Bloomberg, he said. In addition, the Delta chapter of the Air Line Pilots Association recently encouraged its members to back the deal.

Speaking to reporters in Charlotte last month, US Airways CEO Doug Parker said US Airways would be weakened in the New York area, but he noted that even today it has just 4% of the traffic. US Airways would become stronger at National, with more than 50% of traffic.

USAPA's intent is to save jobs and to maintain a strong presence at LaGuardia, said spokesman James Ray. "We've been trying to save the crew bases and US Airways flying out of LaGuardia, which is one of the most highly sought after markets in the world," he said. "We've been talking to the company, but so far that has fallen on deaf ears."

-- Written by Ted Reed in Charlotte, N.C.