EZ77WNCL,
I have an Android phone, and on that I have an app called 'GPS Test'. Once it gets a signal from the GPS sat(s) is shows your lat/long, speed, heading, etc. It doesn't show a map or anything similar, so it doesn't need to access a phone-network.
I also have another useful app ... called 'Open GPS Tracker'. This one *does* download maps so needs to have a connection to a network. The app allows you to create a track of where you've been ... essentially, it records your lat/long every 5 minutes or so ... and records details in a file on your phone. It also shows a map with a trace of your route (which is why the network connection is required). However, you can switch-off the mapping function so that it just records your position every 5 minutes (or 1 minute, or whatever you choose).
It's a bit more fiddly to use ... you have to remember to switch it on and remember to switch it off afterwards (duh!) so that it finishes recording your route.
Both these apps need a clear view of the sky, and they *will* work through aircraft windows, but they won't work elsewhere in the cabin. You will need to have your 'phone up against the window for the flight.