Is this sentence (written by a native English kid) correct?

He was sitting at the wheel awhile ago but he disappeared in mid air the next second.

- sitting at the wheel? I heard sitting behind the wheel
- disappear in mid air? I heard disappear into the thin air

Thanks a lot

At the wheel is fine- we use both. Mid-air could work if the person went flying through the air, but if they just vanished, then I would use your version.