I don't know what you mean by "planes." All airfoil based aircraft have a limitation on how high they can fly before the air gets too thin for their wings to generate sufficient lift (known as their "operating ceiling").
The only exception to this I know of would be a craft with enough thrust to use power as the source of lift (like the space shuttle).
Well, it is a test flight of a brand-new plane. Also, some "planes" can go as high as they want in the atmosphere, even up to space (kinda).