This particular level and visibility of sky writing is new, but "drawing things in the sky" dates back to the 1920s or so. That sort of skywriting uses oil to cause the airplane to leave a trail of white smoke, visible against the blue background of the sky.
The precision we see in this route is fairly new, but, especially on proving flights for new aircraft, which needed hours and hours of flight time and would take off and land at the same airport, and even before the public could see it on a website, filing flight plans that contained (much cruder) drawings of "747" or otherwise certainly exist.
I'd say this is a very different type of drawing, because you only see it on a tracker. Someone watching in real live from the ground wouldn't see the pattern, because I don't think jet trails stay in the air for two hours.
This seems more like people using run/cycle trackers to make drawings on a map. (Strava Art)
We can only see it on a tracker. My claim is that sort of flight route drawing predates modern tracking on the Internet by decades. GPS was released to the public in the 1980's.
Drawing stuff on a map with a GPS track is a rather beaten path in the world of Strava and similar [0]. Not being bound to the road network graph just makes it easier. I don't want to think about the fuel burned for this stunt, but if I were in some position that is required to sign off that flight path I'd sure congratulate whoever came up with this. Wouldn't even be all surprised if tomorrow some Airbus ferry flight would respond in the same medium with a respectful salute to the old lady.
([0] but relative to anything that would be considered a tradition in aviation, the entire concept of GPS is rather newfangled, despite it's surprising age, I'm not disagreeing)
I don't think this uses GPS, at least not directly. This data comes from ADS-B and radar. ADS-B involves the plane itself broadcasting where it (thinks it) is. That may come from GPS onboard but is probably more sophisticated than that in a modern 747.
The ADS-B out data is fed from the aircraft’s ADIRU (air data inertial reference unit), which, yes, just uses GPS unless that fails for some reason. There’s a fallback based on accelerometers and laser gyros to provide shockingly accurate positioning should such a failure occur, but it does lose some accuracy (enough that you can still fly autopilot on it for an approach at max range, but it’ll be drifting by some number of meters) over long flights before it needs to be reset from GPS data on the ground.
