Back in the 1981/1982ish time frame, just before Braniff went under… AA management desperately needed more lift at DFW over the Christmas holidays. Behind the union’s back, they negotiated a quick deal with Braniff to carry AA passengers on AA routes using the AA code. The morning it was scheduled to start, a bunch of AA Captains maneuvered their aircraft after pushback to park and block every Braniff pushback at DFW. They shut em down that morning. The deal was called off immediately afterwards. Obviously I wasn’t around back then but from what I’ve been told, it was a coordinated secret grass roots effort at the membership level that enabled that to happen.