Southwest Airlines (WN, Dallas Love Field) has reached a USD15 million settlement in price-fixing litigation and agreed to "significantly cooperate" in proceedings against the other three defendants, American Airlines, Delta Air Lines, and United Airlines, Law360 has reported.

The four major US-based carriers were sued in 2015 by a group of travellers over the alleged price-fixing case from 2009. The claim stipulates that the airlines colluded to limit the availability of seats on domestic flights in order to maintain higher prices despite falling fuel prices.

"Not only will the USD15 million cash payment provide a monetary benefit to settlement class members, the settlement also preserves their right to recover the entire amount of damages against the nonsettling defendants based on joint and several liability," the parties stated in a memorandum of support for preliminary approval of the settlement.

The group of travellers underlined it hopes that other carriers will follow Southwest Airlines' lead and also enter into settlement negotiations.