How do upgrades work at major U.S. airlines?
When a captain upgrades from say a DC-9 to a B757, does he retain his rank as captain? If so, this would not make much sense to me as he would have much less time on type than his F/O. Also, I have noticed many obviously senior captains flying DC-9's and other single aisle, short range types. Is this because of a limited number of slots on the heavy's, or do many choose to remain on smaller types because of the short routes and more time at home, etc?