In the days before safety became paramount... this kind of flying was only by military pilots generally, but occasionally its still seen by airliners... as shown on these clips.
http://www.youtube.com/watch?v=4HPjPqrnYQI&NR=1http://www.youtube.com/watch?v=9hBTYEMk ... re=relatedWhich leads to warbirds displays...do most warbird pilots have low level flying qualifications endorsed/approved/required or do they prefer to stick to base minimums at airshows in the US instead to get around the safety of low flying?