In the vomit comet ( 0G ) there is always a tiny bit of gravity:
In the vomit comet the gravity is exactly as it is on the earth surface, minus perhaps a mere 0.3% due to the heigth of the plane, let's say 10,000 meters.
People are not bouncing around because there is no gravity.
On the ISS the gravity (meaning the gravitational field) is only about some 12% lower than on the earth's surface.
In both cases the
apparent lack of gravity is due to free falling.