Yes, entering Oceanic you basically tell them: "Request track Delta, Flight level 350, Able 370, second choice track Charly" Translation: I want this route, th

Yes, entering Oceanic you basically tell them: "Request track Delta, Flight level 350, Able 370, second choice track Charly" Translation: I want this route, the best altitude for me is 35,000 ft and at my current weight the maximum I can climb to is 37,000 ft. That optimum altitude is calculated by the flight management system.