This question is motivated by the MH17 tragedy. Following [my other question](Can confirmed passengers preview or request flight plans before the flight?, say that after a passenger learns of or views the flight plan, she opposes it, for reasons of safety, for example.

She could just refuse to board the flight and forfeit her ticket and costs, but are there less costly and dire and radical options? Despite being only a passenger, could she explain to the flight crew (plausibly via the cabin crew?) her reasons and thus request a different route?

As an instantiation, I'd venture that if I had apprehended that MH17 would be flying over Ukraine, even outside of the no-fly zone, then I'd remonstrate against it. I'd prefer a more northern one that would substantively avoid Ukraine.