JB, probably a bit of a silly question but I'll anyway...
Who / what /why determines the route a plane travels on take-off (apart from the obvious of flying into the wind to get extra lift)? On the weekend, I was watching planes take off from BNE on FlightRadar24 and they were departing on runway 01 out over Moreton Bay. Domestic flights going to places such as Cairns, Townsville, Gladstone etc seemed to do a left turn on take-off and then follow the coast line but international flights to Singapore and points in that general direction turned right heading south and did a big loop to the north west taking the 'scenic route' over Brisbane. I would have thought it would have been more fuel efficient to go the same route as the domestics and then turn north-west a bit further north...