Pre GPS navigation
Pre GPS aircraft navigation is amazing, there is so much to take in and you could be in a Vulcan cruising at neatly 600MPH ( 10 miles a minute ). Using Celestial Navigation they could get their position to within about 5-10 miles, it's more of a black magic art coupled with some science.
I'm sure many of you will enjoy exploring, it's a really interesting subject. I've done a quick search and these three links should give you a starter.