To be more numerical, generally non-airplanes are supposed to stay below 500' AGL, and outside airport areas down to the ground as charted on sectional maps. S

To be more numerical, generally non-airplanes are supposed to stay below 500' AGL, and outside airport areas down to the ground as charted on sectional maps. So a jetpack flying around at 3000' sounds like an airspace violation, unless it's over a hilly area to 2500'.