And that's why:
Thousands of planes flyes to a thousands miles every day. All of them use gyroscopes. Gyroscope shows the airplane orientation in the space. It resists any deviation. It "save" original orientation. So even in clouds pilot can see if plane goes up or down.
Now look at the picture: while fluying to his destination, the plane is moving along an arc around "globe". But if so - its nose should decrease in relation to the initial position fixed by the gyro.
But i've never heard about this problem. Throughout the all flight's no matter how long they're distance, gyro always works with no problems.

So, the Earth are flat. Gagarin diddn't fly to Space. Americans has never fly to the moon. It's all bullshit. I'm drunk.