I still remember the first time I flew on my own... heading back to Semenanjung from Sarawak... I sat beside an elderly Phillipino lady... we chatted throughout the flight... I learned of her life story, and she learned of mine... that I wanted to become a doctor, my family back home...
I enjoy chatting with the person sitting beside me on the plane - provided that I'm not too nauseatic from air sickness, or that the person doesn't stare daggers at me, wishing that I would flush myself down the airplane toilet.
Perhaps it's because spending more than just a few minutes with a complete stranger sitting next to me compels me to be a bit friendlier than to just smile insipidly at that person when he / she tries to squeeze past me to get in and out of the aisle, or the other way round.
Either that, or I'm just plain nosy. :P