From MSNBC:

An American Airlines flight en route from Chicago to Miami was diverted to Nashville, Tenn., at 12:20 p.m. CDT when the pilot fell ill, according to Tim Smith, a spokesperson for the airline. Smith said it was unclear whether the pilot was flying the plane or what type of illness led to the diversion.
Flight 2050, a Boeing 777 carrying 213 passengers, made a normal landing in Nashville, but has remained on the tarmac since the airport's gate and jet bridges are not equipped to handle wide-bodied aircraft.
The airline is in the process of determining how to get passengers to Miami. According to the Tennessean, the sick pilot is in stable condition and has been taken to a nearby medical center. The airline is reportedly considering adding a new pilot to the flight, bringing in a new plane and crew or canceling the flight.
The Tennessean also reported that one passenger became ill as well, but there were no details about that person's condition.
The flight was originally scheduled to land in Miami at 2:40 p.m., but the airline's website has changed the arrival time to 6:52 p.m.

Overhead Bin - American Airlines flight diverted after pilot falls ill