How low can a plane legally fly?
The FAA has rules about flying over populated areas. Except when approaching or departing an airport, a plane may not fly lower than 1000 ft over a populated area. Elsewhere, a plane may not fly within 500 ft of any person or building or vessel. Since there are buildings and persons in the area surrounding Healdsburg Airport, this basically means that any pilot who flies an aircraft lower than 500 ft AGL, except during takeoff/landing, is violating Federal law. If you see an aircraft flying below this legal altitude or in any other hazardous manner, you should try to get a good look at it. Note whether it’s a high-wing (wings above the cabin) or low-wing, number of engines, and color. If you can record the tail number (begins with “N”, painted on the tail or fuselage), the FAA can use that information to trace the owner of the plane.
Going to point this out to you because you are missing a big point here. From 91.119 we can actually fly as low as we like as long as A) we aren’t in a position that an engine failure would cause undue hazard to other (not in the airplane) persons or property on the ground and B) we are 500ft from any persons, vessel, vehicle, or structure . So over a lake or sparsely populated area as long as we maintain 500ft separation from something we can fly as low as we wish. the rest of what you said about the 500 and 1000ft rules is correct. If you’re going to post answers here and suggest someone contact the FAA the least you could do is actually include the whole regulation.