Originally Posted by
H5487
Except for the landing and takeoff phases (and perhaps cropdusting and law enforcement ops) full-scale aircraft don't usually operate below 500ft above the highest obstacle in sparsely-occupied areas, 1000ft in congested areas.
Keep in mind though the military does it all the time. All across the country there are Military Training Routes, where aircraft routinely operate below 500 feet and at speeds of 420 KIAS or more. Some of these are even flown at night using terrain following radar and/or FLIR. These routes are shown on sectionals as VRs, IRs, and SRs. But what most RC folks don't know is these routes can be up to 20 miles wide in places, and they're not always in sparsely populated areas. One of my favorites is a route that ends just west of Dulles.
If you've ever seen the Blues or T-Birds perform, you also know that even a subsonic aircraft can be on top you before you hear it for more than a second or so (not enough time to "avoid" per AMA & FAA rules).
Having nearly lost a jet when I hit a sparrow in the windscreen at 420 indicated on a VR route, I can only imagine how much damage would have been caused by a 2lb or more sUAS at that speed.