In the May lawsuit, three men - who were not seated together and did not know each other - said that every black man was removed from the flight between Phoenix, Arizona and New York City.
A total of eight passengers were removed.
In a separate incident in 2017, the NAACP warned black travellers to avoid the airline, citing a pattern of "disrespectful" and "discriminatory" behaviour as well as a "corporate culture of racial insensitivity and possible racial bias".
They lifted the advisory the following year after the carrier announced it had made changes to its operations.