This is the 14794th most frequent Turkish word.
rotayı
"Rotayı" means "the route" or "the course" in English.
The word 'rotayı' is used in the accusative form here to indicate the 'route' as the direct object of the action.
Pilot, rotayı güneye çevirdi.
The pilot changed the route to the south.
In this sentence, 'rotayı' again is in the accusative case to show that the 'route' is the thing being determined.
Rotayı belirlemeden yola çıkmak tehlikeli olur.
Starting a journey without determining the route would be dangerous.
Here, 'rotayı' highlights the specific 'route' that was supposed to be followed, emphasizing its direct-object role in the sentence.