In a video, a Swiss International Air Lines crew flies an Airbus A340-313 (flight LX38) from Zurich to San Francisco. Then, they can be seen (I am not sure if this is on the very same day) visiting downtown and the Golden Gate prior to getting back to the airport for the return flight (LX39), which is scheduled for departure around three hours later.
The question here is:
How do airlines handle crew turnovers in long-haul flights?
Is it the same crew who is demanded to command the return flight? Or is there, oddly enough, a replacement crew in each destination airport? Or do they carry the crew for flight LX39 onboard flight LX38?