With 40 minutes or so of gps riding a day I have to charge the phone every day. Sometimes I forget or other times I have longer rides/hikes and get low battery away from my charger. I typically put it into airplane mode then. What I noticed is that if I go into a run or biking activity it turns GPS back on without telling me. Both of those modes do have a mode to work without GPS. I'm surprised it doesn't stay in airplane mode if I put it there. I don't want to have to dig through the menu when I start my ride to figure out how to setup GPS free ride.