The DOT has granted Spirit Airlines the right to operate more flights at Newark Airport.
Southwest left 36 daily slots when it stopped serving Newark. The landing rights have been rearranged.
The Transportation Department asked low-cost carriers and ultralow-cost carriers to submit applications for the remaining slots after a court order called for increased competition at Newark.
The slots were won by SPIRIT. Only four daily slots were available for Alaska Airlines.
The DOT said in its announcement on Monday that it was most likely to give the lowest fares to the most consumers.
Newark flyers are having significant disruptions this summer due to construction as well as airline, airport and air traffic control staffing shortages, but the department awarded the slots. United decided to reduce its schedule at Newark due to airport congestion.
In April, Scott Kirby, the CEO of United, accused the two airlines of operating more flights than they are supposed to. The schedules of the two airlines were trimmed.
The DOT incorporated concerns about Newark operations into its decision by requiring Spirit to report more data on disruptions that impact its customers.
The department will be able to better quantify the financial impact of operational disruptions on travelers thanks to the reporting requirements.
According to the most recent data from the Bureau of Transportation Statistics, Spirit was the third-largest carrier in Newark for the year ending in March. The second largest carrier at the airport was JetBlue. More than half of Newark flyers are flown by United and United Express.
The DOT's selection of the airline comes at a time when the airlines are in a bidding war.