Two dozen black pilots alleged in a lawsuit on Tuesday that United Continental Holdings, the parent of United Airlines, passed them over for management promotions because of race.
The world's biggest carrier denied the allegations and said it would fight them in court.
The veteran aviators alleged a long history of discriminatory behavior across multiple U.S. states. Their suit was filed in the U.S. District Court for the Northern District of California in San Francisco.
"The struggle for inclusion at United Airlines is a long-standing issue that many have tried to address over a long period of time," Captain Leon Miller, a plaintiff, said in a statement.
Most of those involved in the suit worked for pre-merger United. The complaint specifically addresses promotion issues dating to 2009.
In addition, nearly half of the plaintiffs were part of a 2010 federal equal employment racial discrimination case against United, and are claiming the carrier has punished them by withholding promotions and special assignments.
United said in a statement that it does not tolerate harassment or discrimination.
"We believe this lawsuit is without merit and will vigorously defend ourselves," the airline said.