Flight-path for me means trajectory through the air. But it can colloquially mean a route.
Since we have a route tag, I imagine flight-path does indeed refer to the trajectory. It does lack a tag description though.
Yet most questions for flight-path are about routes. So I wouldn't force a description really and retag a bunch of questions.
What should we do about it?
Update after 1.5 years: I've split the answer. The action taken (?) was opposite my recommendation (now posted separately), I believe in error. The flight-path tag is now the master, with the route a synonym.