The Reason the Plane Cannot Fly into Space

The current highest flight record is 37,652m by Alexandr Fedotov in 1977, but this is only 1/3 of the way to space. So why, can it fly in the air but the plane cannot fly into space like a spacecraft?

The main reason the aircraft cannot fly into space like a spacecraft is the gravity of the Earth and the dilution of the atmosphere. Check out the video below to know how these two factors have affected the plane!