You can file any flight plan you wish, as often demonstrated in the US by certification flights "painting" logos and letters into flight tracking paths. Perhaps even more impressively, NASA's SOFIA modded 747 (
https://en.wikipedia.org/wiki/Strato...ared_Astronomy) is always flying paths specifically geared towards observing specific targets on the sky and flies oddly shaped flight paths for that reason, both in the US and over the pacific, as well as when operating out of NZ for the southern deployment missions over the south pacific, tasman sea, and all the way down to Antarctica on occasion.