On the flight deck there are usually 3 pilots. A captain, a first officer and an international officer (or relief pilot). There are not 2 FA crews. Maximum staffing on a 747 is 18, I think 16 on a 777 and not sure on the 767. UA has different (higher) minimums than FAA requirements, if there are fewer flight attendants than UA minimum they can still fly providing they have FAA minimum. In that situation the FA's receive extra pay.