That phrasing sure makes it sound like they're not in the park until they fall. Does it occur the moment they hit the ground, or sooner? If ground, then that tells us that the quadcopter isn't in the park while off the ground either; it's above the park.
That phrasing sure makes it sound like they're not in the park until they fall. Does it occur the moment they hit the ground, or sooner? If ground, then that tells us that the quadcopter isn't in the park while off the ground either; it's above the park.