No. Not unless something interesting happens (which on an airplane is usually never), then I might make 30 seconds of smalltalk. I’m somewhat social in general and talk way too damn much, but I can’t be that way everywhere all the time. Plane time is STFU time for me. If someone chats me up, I’ll be as brief in response as I can be while still being polite.
Speaking of strangers on planes, trains and automobiles, what happened to Stranger on a Train?
Option 2 should be divided up into multiple possible outcomes, i.e.:
Since you don’t know whether you’re going to get 2a or 2b until it happens, the risk of 2b is enough that many people, myself included, won’t even attempt 2a.
I will also point out that if someone has headphones on, is turned away from you, and is reading a book or using an electronic device, then if you persist in attempting to make conversation anyway, 1) you’re the one who’s being rude, and 2) you are a complete idiot about how social interactions work.
I’m horribly shy if I’m on my own so I don’t chat up fellow passengers. If one starts a conversation, I will volley back, but that’s about it.
Recently, I was on a flight to San Francisco and had the window seat. In the middle seat was a woman in her 60s with pigtails and carrying a Mickey Mouse backpack. A rather average man in his 50s was on the aisle seat. They were strangers to each other. I exchanged some pleasantries then put on my headphones and read a book in my Kindle. I changed albums a couple times and heard snippets of very, very intimate conversations about her abortion and his upcoming prostate surgery. I was so glad for my iPod at that moment.
Ah, so there are other options! 
I was just responding to kayaker, whose posts implied that there are only two options.
Okay, I get the basic point. What I don’t understand is why is it so difficult to just tell the person: “Hey, nice chatting with you. I have some reading to do”? Or, “I just need to relax”. Or whatever it is that you want to do instead of talking with a stranger.
It seems that some of the posters in this thread don’t mind talking with strangers (at least some of the time) but they don’t want to get stuck in a long, unpleasant conversation. But, if you can avoid this at the beginning of the flight by having your earphones on (or whatever else you do to avoid interacting with other passengers), why not just interrupt the (boorish, obnoxious, self-centered) person and tell them what you want to do? It seems to me that, once the unpleasant conversation starts, some people would rather suffer for a few hours rather than just tell the other person that they want to do something else. I realize, though, that if you think that there will be no benefit from talking with a stranger, then it makes sense not to engage in any conversation.
Yeah, you’re right. So what do you do, without being equally rude or being a complete idiot? I’ve found that almost everyone is aware of social norms and boundaries, but their idea of boundaries might be different from yours. Regardless, I’ve found that almost everyone will respect the other person’s boundaries in a neutral setting like a regular flight in a commercial aircraft. And, for those real nut-cases … well, you just gotta do what you gotta do.
I prefer to completely ignore them. If someone attempts to strike up a conversation with me, I’ll usually answer the question and nothing more. I try really hard not to be rude, but I’m not interested in socializing on a plane. Generally, I’m either a) enjoying the rare free time I’ll have to sit down and read a book during the day, b) trying very hard not to vomit (motion sickness, usually only bad at night or on particularly bumpy flights) or c) trying to work and don’t want to be interrupted.
Here, enjoy! (Strangers On My Flight)
This is why, when you see your buddy Jack, you don’t say high. 
(is it creepy that this guy has the Hitler mustache,…and even the haircut?)
I’ve also had some really interesting conversations with people seated next to me. One was from my home town and knew my godmother. Another knew my boss. Someone told me things to see/do in Raleigh while I was on a flight headed there. Last winter I had a really fascinating conversation with a women who had been in Northern Minnesota looking for owls. When it was -25 out. And she was from San Diego so it was the coldest weather she’d ever been in. I enjoy bird watching, although not to that extent, but enough to thoroughly enjoy the conversation.
I don’t talk to anyone who puts headphones on right away or who pulls a book out. And I generally won’t initiate the conversation. But I usually have knitting with me, and often people will comment on my knitting, which makes a natural conversation opener.
Talking’s a good way to pass the time. And I agree with Galileo that the solution to people who don’t take the hint to stop talking is just to say “I’ve got some work to get done” or “It’s been nice chatting, but I’d like to read now.”