United Airlines CEO Scott Kirby on Monday outlined why he thinks a merger between his airline and rival American would benefit travelers, despite American’s refusal to engage in negotiations. The stocks of both airlines soared two weeks ago when reports surfaced that Kirby had floated the idea of combining two of the biggest U.S. airlines to the White House. Kirby said Monday that he had approached American directly about a tie-up, but it’s unclear whether that was before or after the White House meeting. Days after the meeting in Washington, American shot down the idea of a merger.