Some of these things involve preparing beforehand, so for your sake, I really hope you're not on that plane yet.
1. Strike up a conversation
In today's day and age, most people would rather stick their faces into their phones, pretending that likes and Facebook tags and Snapchat stories count as human interaction. Be the change. Start with questions that are open-ended and give them room to tell you they're not really interested in a conversation. Or, open up a little bit about yourself, such as sharing the reason why you're traveling. Sometimes they don't want to talk, and that's okay. Sometimes you'll find yourself in one of the most interesting conversations of your life.
2. In-flight entertainment
Airline companies are really stepping up their game! This does depend on the plane you're in, and typically also depends on the duration of your trip and the class of your ticket, but the other day I took a 2-hour Delta flight in economy and watched "Avengers: Infinity War." I was pleasantly surprised that one, it was offered in economy, two, it was offered on a rather short, 2-hour flight, and three, such a popular, new movie was available. Always worth checking out that panel!
3. Listen to music
Depending on whether you will have WiFi on your plane or not, you may want to download your favorite playlists onto your phone beforehand. Typically planes charge extra for WiFi, and since I'm a Spotify Premium user, I can download my playlists. Other music apps have their own management systems, so be sure to check yours and get your music offline for the flight.
4. Read books
Yes, this requires some level of preparation. Nowadays e-readers are popular, but I still prefer paperback books, and that means heading to my local library and packing it beforehand. Airplanes can be a little uncomfortable, but they're usually quiet and a good way to disconnect from your phone and social media and get some quality reading time.