Step 1. Start with a picture that's easy to find, such as a large recognizable land formation. This one only took a couple of minutes to find.
Once you find that picture, you know which way the airplane window is facing. And if you have timestamps on your pictures, you can estimate how many miles there are between them. Just take the difference in minutes and multiply by 10.
For example, the picture above has a timestamp of 1:30:42. The picture I took before that has 1:24:25. That's a difference of 6 minutes, 17 seconds. Take the seconds, divide by 60 and add to the number of minutes to get 6.28. Then multiply by 10 to get 62.8 miles.
Once you have distance, you can estimate the direction of the airplane. They like to follow curvy paths (along great circles on the globe). So, if you start with the location of picture #1 and draw a line toward (or away from if going backwards) the destination point, and draw a line away from (or toward) the departure point, it will narrow down the location of your next picture. (You can check out my very last picture at the end to see the lines I drew.)
I was surprised how fast I found the next obscure picture ...
I challenge you to try the same game should you remember next time you're on a plane. Can you find your pictures? Have fun, and good luck!