I plan to go hiking in an area where I do not anticipate there being much cell coverage at all. What there is will likely be very spotty. I would like to use the All Trails app to track my progress using the built in GPS in my iPhone 4S. I don't need any data while I am actually hiking (and tracking my progress with GPS). My concern is that the phone will uselessly drain it's battery trying to find cell signal when it could have made it easily through the day if there was a way to force it to stop looking. The problem with Airplane mode is that it shuts the GPS off as well.
Is there a way to conserve battery and use the GPS?
I could get a solar charger or battery charger but would prefer not to.