For most of the month of June, the skies above Traverse City have been visited by one particular Gulfstream-IV business jet. This G-IV visited several times and sometimes more than once per day, including last Tuesday and Wednesday. This airplane didn't land at Traverse City, merely circled at 43,000 feet, putting out circular contrails easily seen from the ground - and then went back to its base at Willow Run Airport in Ypsilanti. According to the Traverse City Record-Eagle, this prompted calls to 911 by residents. And then things got weird.

Enter your number to get our free mobile app

According to a YouTube video from MT Aviation Photo & Film, this particular aircraft has been modified in a way rarely, if ever, seen on one of these Gulfstream jets, which are commonly used by corporate flight departments or as charter jets. On its left side, the aircraft windows have been modified  to support some sort of optical feature. Some speculate the new "window" is for photography (I can't wait for THESE "Pure Michigan" TV spots). Others question, "why from 43,000 feet?" The YouTube commentary suggests that the modification, which happened at Willow Run, might have something to do with drone technology.

Or, it could be that a crew, or multiple crews, have been doing flight training, including "holding pattern" training or practice. Or, they may be testing their new camera (if that's what it is) in an out of the way place where the weather is nice and there's not much air traffic. Whatever's going on, those flying this aircraft haven't been very talkative when contacted by air traffic control.

What do YOU think?

Here's the story.

And here's the YouTube video: