DALLAS — American Airlines and US Airways said Monday that they won’t appeal a court official’s decision not to force the Justice Department to reveal certain documents and third-party interviewee lists to them.But both carriers said they remain confident of winning the antitrust trial and eventually merging. A decision is expected by early January.AMR Corp.’s American and US Airways Group wanted the department to explain why it approved four prior airline mergers but opposes theirs. They wanted to know whom the government’s lawyers interviewed as they prepared the lawsuit.A retired judge hired to help the trial judge generally sided with the Justice Department last week, saying it could keep most of the information confidential. Fort Worth-based American and Tempe, Ariz.-based US Airways could have appealed to the trial judge. The airlines believe that the department is judging their merger by different standards. They wanted access to the department’s documents to show that under the economic assumptions used in the past, their merger would increase competition, not reduce it. The trial is scheduled to start Nov. 25 in a federal District Court in Washington.