Triangle craft

Back story, i got this from a law enforcement friend who works near a major airport. He sees weird stuff all the time. As a joke he calls it in to the control tower every time. They tell him “they know about it and could he please quit calling.” He sent me this photo he took. It was very near dark but still a little light left in the sky. Triangle craft hovering above power lines. Says he observed it for about 10 minutes before he got a call. He says if you want to see one just show up about dark and hang out. They are always around the airport. Photo is a couple years old. Very clearly shows a dark triangle with three lights hovering just beyond the power lines. The photo is a little dark but still really good. Any ideas what’s going on around out airports?