The US Airline Pilots Association said it sent a letter to the Justice Department seeking a full investigation on the impact of the proposed transaction between US Airways and Delta at New York's LaGuardia and Washington's Reagan National airports.
The dispute pits the US Airways pilots union against its counterpart at Delta, which supports the slot swap deal. The Delta pilots union encouraged members in a memo Nov. 6 to help in the effort to get government approval.
In August, US Airways said it had agreed to transfer 125 operating slot pairs to Delta at LaGuardia. In exchange, Delta agreed to transfer 42 operating slot pairs to US Airways at Reagan National.
Slots, especially at peak times of day and in busy corridors like the Northeast, are valuable to airlines.
A slot is an interval of time during which an airline can take off or land its aircraft at an airport. A pair refers to cities airlines fly between.
The same week as the Delta-US Airways deal was announced, it was disclosed that AirTran Airways planned to stop flying to and from Newark, N.J., effective Oct. 25 and would give its takeoff and landing slots there to Continental Airlines Inc. in exchange for Continental slots at LaGuardia and National airports.
Continental has a hub at Newark Liberty International Airport, which is used by many travelers heading to or from New York City.
US Airways' pilots union said it believes the Delta deal may raise antitrust implications.
"We are extremely concerned about the market concentration that this transaction would create if it is allowed to be consummated," union President Mike Cleary said in a statement. "Those conditions raise the prospect of much higher fares and, if history repeats itself, a reduction in service to smaller communities."
A spokesman for Delta Air Lines Inc., based in Atlanta, said nearly 10,000 of Delta's customers and employees have voiced their support for the proposed transaction directly to the Transportation and Justice departments. US Airways Group Inc. spokeswoman Michelle Mohr said her airline, based in Tempe, Ariz., believes the transaction will pass government review.
It's not clear when government regulators will reach a decision.
The transaction would add 11 gates to Delta's LaGuardia operations. The world's biggest airline operator has said the deal would allow it to create a domestic hub at LaGuardia, even as Delta maintains a strong presence at New York's John F. Kennedy International Airport. At the Washington airport, Delta said previously it expected to cut its daily departures from 89 to 55.
If its deal is approved, Delta has projected it would operate nearly 30 percent of the total available seat miles from the three main airports serving New York City. Available seat miles measure an airline's capacity for carrying passengers. It equals the number of seats available multiplied by miles flown.
US Airways, meanwhile, has said it would expand its service at the Washington airport and reduce its Express flights at LaGuardia, while mainline and Shuttle flight levels would not be affected.
The airline's regional carrier Piedmont has been expected to be hit hard by US Airways' plans to discontinue service to 26 destinations served by US Airways Express. The airline has said that would result in the elimination of roughly 300 Piedmont positions at LaGuardia when the reduced flight schedule is implemented in early 2010.
The US Airways pilots union is concerned the deal will place a burden on many of US Airways' New York-based employees whose jobs will be eliminated.
But Delta's pilots union said the agreement will allow more than 2 million additional passengers to fly at New York's preferred domestic airport every year without increasing congestion, moving Delta closer to its goal of becoming the top airline in New York. The union urged members to contact lawmakers in Washington to express their support for the slot swaps.