If the earth is round, then how come planes ,which fly level, don't fly off into space?

beacuse the earth isn't round, its flat

1. The planes have pilots and instruments to adjust flight path.
2. If the earth is not an oblate spheroid, post a picture.

They actually do. *snif* SO many lives lost!!! So much sorrow from imagining air travel could be possible *bwaa ha ha haaaaaaa!! (uncontrollable balling)*

If they're flying level then that means they're maintaining a set altitude. A set altitude of 40,000 ft over one part of a sphere is still 40,000 ft. somewhere else on the sphere.

Because of solar wind.

If you’re not viewing the earth from space, it obviously looks flat. It’s the same situation with planes. Planes are heavily impacted by the gravitational pull of the earth. It may look like they’re flying level, just as the earth looks level from the typical person standing on Earth, but in reality they fly at an EXTREMELY slight curve that matches the curvature of the earth due to gravity. No, this is not but choice of pilot, it just happens. Hope this helped.

They are flown by level headed pilots.