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.