HKG to IAD with a transfer in NRT using a "C" ticket. When checking in at HKG they apologized and said all segments were over booked. Instead they moved me to a new itinerary that add a transfer in ORD but moved me to "F" for all segments.

The icing on the cake was that the new itinerary somehow got me to IAD earlier than my original (for once, no delays in ORD).

Once in a while it works out.

Craig