A man conducted "an experiment" (quotes really, really necessary) to prove that earth is flat. Here's a link. He used a spirit level, set it up before takeoff and expected the level to be tilted after landing, becase since the world is round, the destination would be tilted in relation to origin. Well that failed, because gravity works differently than he anticipated.
I'm fairly sure I know the answer, but... What would happen if he had used a gyroscope instead? Wouldn't that work? Wouldn't gyroscope be tilted in relation to Earth's surface after landing?