US Airways and American Airlines are extending their merger deadline by one month to give themselves time for the anti-monopoly trial scheduled for November. The trial is scheduled to start November 25. The airlines’ original agreement allowed either side to quit the merger by December 17, but the trial might not be concluded by then. The new agreement extends the period until January 18, or later if the court rules in favor of the airlines. The U.S. Justice Department has sued to prevent the planned merger, saying it will hurt competition in the commercial aviation industry.