No you are incorrect. You are missing the point about altitude relative to the Earth's surface. If you can't get this part right, then all your other theories will hold no weight. If you want people to accept your flat earth theory, you at least have to understand the most basic facts of life. In a round Earth the plane does not turn when going straight. How can you even say this? Follow a line as I described, You do not turn. Take anything round, let's say a water bottle and do the same thing. Put a pen point on it then move the pen around the bottle. The pen does not go east and west, as long as it keeps the same distance to the bottle. Take a plate. Lay it on a table. Put your finger on the plate, now go straight keeping the same distance you fall off of the plate, therefore you would need to steer.
If you still do not understand here is another example.
Imagine you are on a car on a gigantic ball. You're car is somehow stuck to the ground and can't fall off. The car goes around the earth such as from the US to Europe to Asia back to the US in a straight latitude type line. He can keep the wheel totally straight and he will circle the ball and end up exactly where he started.
If the car was on a round race track and he was going in his lane, he has to steer the wheel around every curve.
I hope you see the difference now. If you still do not see how a plane in a round Earth just goes straight and a flat Earth you need to turn, then I refuse to discuss anythign else with you, as you will just be a waste of my time.