Given that they flew this below 15k feet, not requiring the full IFR flight plan which would be required above that altitude, I suspect they might have hand flown this out by Moses lake by following a magenta line on a map.

They could have also just programmed the FMS with the waypoints and the plane flew itself.

It appears that flight was flown IFR as the cleared route is available: SEA V120 EAT 4700N/11924W 4723N/11930W 4714N/11915W 4712N/11901W 4714N/11848W 4728N/11831W 4714N/11816W 4711N/11803W 4714N/11750W 4722N/11733W 4707N/11739W 4708N/11811W 4708N/11856W 4706N/11926W 4637N/11918W 4638N/11909W 4657N/11856W 4657N/11913W 4701N/11913W 4701N/11849W 4637N/11904W 4638N/11831W 4657N/11831W 4645N/11841W 4645N/11831W 4643N/11831W 4643N/11849W 4701N/11834W 4701N/11827W 4638N/11826W 4638N/11813W 4657N/11800W 4657N/11816W 4701N/11816W 4701N/11753W 4637N/11807W 4637N/11749W 4707N/11739W 4713N/11737W HLN DPR MCW JOT CEGRM5

Since the clearance includes a STAR, I'm suspect it was all filed IFR.

That is an amazing IFR flight plan. I wonder if someone captured the readback on the radio. You’re cleared to the Cincinnati airport via ……

Yeah even one step easier is following the flight director that tells you where to point the plane from a first person view.

You can literally just give the flight computer a list of lat-lons and have it fly arbitrary routes in the sky in 3D.

If I was going to do it with my avionics, I'd do it with GPS user-defined-waypoints driving the auto-pilot.

> Some of the turns are way too tight to be done by the autopilot.

Not sure what you're looking at, but this is absolutely incorrect.

> I would suspect some custom control system was used.

Not a chance in hell.