Know how they say you're supposed to picture members of an audience naked in order to calm yourself down for public speaking?
Next time you board a plane, just imagine what everyone in there would look like screaming and freaking out moments before impact. Envision the people in the back crying out for help as the fuselage snaps in half and they get sucked out of the plane and fall away screaming into the inky blackness of the cold night sky. See the polite strangers sitting next to eachother exchange a final look of terror through the liquid fire atmosphere with their precious oxygen masks melting to their charred skin, before their eyeballs boil out of their skulls and they endure their final moments in a sightless deafening world of hellish agony.
That always cheers me up.
If it doesn't work, just talk to the person next to you. "You know, I may be the last person you'll ever see" is a pretty good opening line.