Well well well… what have we here, if not the french Q plane I spotted here: >>5024045 (pb)
Looks like I was right about NorthWest USA…
I don't know, it's actually very close to the shortest path considering the actual shape of the earth compared to the 2D map we look at in ADSB-E.
But still, have not seen that type of activity before, so still worth to keep an eye on.