Inertia. Think of when your driving your car. Your car is moving, and you are in your car, so you move. People, the air, and planes are all on the earth, so they are all moving at the same speed as the earth. Also, the earth is not excelerating; in order for it to excelerate, something would have to be moving it.
you can see planes fly. the proof is right infront of you. try googling how planes fly.