often, these are people with some kind of flying fear, their method of dealing is to talk incessantly!! IF the person is BORING (frequently the case!) it can drive one crazy! -one has to be out and out rude, to be allowed entry into ones' own personal world!
i use two methods for dealing: (1) headphones/ipod & (2) faking like i've fallen asleep! -books are good too, if you get 'into' the book immediately!! and act totally enraptured, which you CAN be, if you have the right book!
an in-flight motormouth tortured me all the way to poop town!!
we experienced terrible turbulence which help distract my in-flight motor mouth!