I want to start off saying that American Airlines did the right thing. We had a "maintenance" issue that delayed my 09:00 flight from Chicago yesterday. They take pride in their on-time departure record. However, we had a situation that downgraded the ability to perform a reduced visibility landing. They delayed the departure while they worked on the airplane. A decision was made to replace the plane. We wound up leaving at 10:45, 1 hour and 45 minutes late, but in a safe condition. My hat's off to AA.