>>5070163 (pb)
>>5070012 (pb)
Not that uncommon.
http://www.thedrive.com/the-war-zone/11502/nightstalkers-show-off-for-the-public-with-a-dramatic-urban-air-assault
https://www.twincities.com/2014/08/18/helicopter-training-over-cities-continues-through-thursday/
https://www.nola.com/military/index.ssf/2013/04/mystery_copters_over_new_orlea.html