A plane ride is a time of spiritual elevation. I mean, you are mamesh mamesh in the clouds. In shomayim! Thankfully, you get to come down [as opposed to those who go to shomayim and don't return...].
Example - davening. On my latest trip I brought along a sefer called Shearis Yosef [Vol. 7] and lo and behold he has an article about minyanim on airplanes. He is opposed to the practice. So were Rav Shlomo Zalman, Rav Ovadiah Yosef, Rav Soloveitchik and many other luminaries. One may not conduct a public tefilla if it will disturb the sleep of others. What a great tefilla - no tefilla bi'tzibbur so as not to wake others. A bein adam lachaveiro'dike tefila! So you daven privately and wonder of wonders - nowhere to go!! People always seemed so rushed to get somewhere but on a plane it's either your seat or the restroom. Neither of them particularly exciting. So you can just daven and daven. You don't have to keep pace with anybody else [i.e. skip in order to keep up]. Ah mechaye.
Learning - You can learn and learn without interruption [unless they come around with those "facial tissues" which for the record I never take]. No telephone, no cell phone, no internet. Pure learning.
סור מרע: You can eschew the various forms of entertainment that are so deletorious to the soul. You can also eschew chewing gum but that's besides the point. [If you think I wrote this post just so that I can use the word "eschew" you may have a point..]
Teshuva - You can think "Large metal bin 35,000 feet above the Atlantic. Never met the pilot. May he is a druggie and we are goin' down". This will prompt you to do QUICK TESHUVA!