Firstly, if you saw a pretty blue and white 747 and you were “highly certain” that the President was not aboard, then you DID NOT see Air Force One.
Air Force One is the call sign given to the aircraft carrying the President.
You might have seen one of the aircraft used for this purpose.
Those 747s usually fly normal 747 type flight paths and altitudes.
I am not sure what you saw – maybe the crew were sightseeing, maybe they were taking marketing pictures of the President’s latest golf resort, maybe they were training somehow, maybe they were on an extended approach to land.
Flying low is not necessarily dangerous – as long as you know what you are doing and where you are going.
