"It seemed like they were aware of our presence, because they would actively move around us," Lt. Accoin said.
According to the lieutenant, when a strange reading shows up on radar for the first time, it's possible to interpret it as a false alarm, "but then when you start to get multiple sensors reading the exact same thing, and then you get to see a display, that solidifies it for me."
https://www.livescience.com/65585-ufo-sightings-us-pilots.html
Hadn't heard of Lt. Accoin's account before.