Long Flights

How does crew rotation work on a really long flight? i.e. KDFW to YBBN, 14-15 hours.

I haven’t been on that flight in particular, but I’ve observed on other ultra long hauls -
Cabin crew: one set of cabin crew for departure, dinner, breakfast, and arrival, another set of cabin crew handles the non-mealtime in the middle of the flight
Cockpit crew: 2 captains and 2 FO, not sure what their scheduling is but probably something staggered

Some airlines just use 1 captain and he or she will be on deck for take off and landing,
then resting in cruise. Other pilots will rotate as needed resting in first class seats
or crew bunk beds depending on airline and trip length.

Lufthansa flies this route with B744 and 3 pilots, if the A340 was used because of
lower cruise speed, the route would need 4 pilots.
flightaware.com/live/flight/DLH5 … /EDDF/SAEZ

Turkish uses 4 pilots on this B77W flight.
flightaware.com/live/flight/THY9 … /LTBA/KLAX

Singapore uses 5 pilots on this A345 route.
flightaware.com/live/flight/SIA2 … /KEWR/WSSS

This delivery flight of a new HA A332 also used 5 pilots.
flightaware.com/live/flight/N382 … /LFBO/PHNL