How can you navigate "Writing" onto FlightRadar Plans? Sorry if the question title here is a bit misleading, the graphic here should explain all:



I read a news story this morning about how a guy flying a Robin DR400 regularly creates inventive patterns in his flight tracks.

Source

The question is, how would the pilot be able to create this writing (and other creative patterns)?  Autopilot instructions?  Watching himself on FlightRadar?
Most Robin 400s don't have autopilots, but some do. Whether it has an autopilot or not it was almost certainly navigated using a pre-set course which was fed into a GPS. One would use flight planning software to create a course using a series of waypoints which would then be uploaded to a built-in or handheld GPS, and then either flown by hand or followed by an autopilot. 

You can see that the curves are mostly a series of small straight lines, I think that these straight lines are the space between waypoints, it could be the refresh between the FlightRadar inputs causing the lines though.