The craziest member of the A-Team resided in a military mental hospital for most of his time and it wasn't hard to see why. Running through different personalities like a hot knife through butter, and talking randomly to objects and things that did not exist. B.A. had a particular problem with this "crazy fool".
However, despite his umm.. inconsistencies, Murdock was a top class pilot. He'd fly anything and fly it well - if a crash was iminent he was the man to get the 'plane down safely. Despite his mental state (and was he really crazy?), he was an irreplacable member of the Team.