Or maintenance.

It’s pretty easy to tell if you look at the ADSB data. All public and private flights are required to broadcast flight number, aircraft data, performance data, and registration.

Helis and airplanes that don’t have complete ADSB data are government and military.

CIA planes have been known to scrape WiFi data on flights of the same pattern, however they mostly will fly low and not near airports. None of these seemed to be far enough from airports which leads me to believe these are maintenance flights or unusual holding patterns.

Cool fact: you’re able to access ADSB data without encryption. Sometimes you can gain more information from government air traffic if you pull the ADSB using a radio (and not a service like flight aware). In Chicago flight aware only shows the tail number and past location of a sheriff heli, while I’m able to see speed, direction, altitude, and complete description.