Important difference here, a GPS is direct satellite navigation. Any smartphone 
app is triangulation beteween cellular provider towers which are line of sight. 

Cell phone based navigation is great if you are in such fortunate locations to 
be with service bars enough to keep that connection. GPS is more robust when 
you leave the areas of cell tower coverage, be that by distance into sparse 
population areas, away from interstates or into terrain so up and down that 
cell service “shadows” break coverage. 

Know that GPS is somewhat line of sight as well, they are susceptible to signal 
degradation by heavy overhead foliage (springtime when leaves are pulpy and 
growing fast or wet from recent dew, rain) and atmospheric phenomenon between 
you on the ground and the satellites. The scene in Lone Survivor when Lt. Mike 
Murphy leaves cover to go out on an open rock area to make the satellite phone 
call for help demonstrated the same problem. These signal degradations always 
seem to coincide with the moments you usually have the greatest need for 
navigation or location advice. 

If you really want to maintain navigational awareness you may have to keep 
cellular or GPS based device information backed up with real map. Reporters 
here represent each of these ways to navigate, Patrick says he uses several 
(for contingency) which I practice myself. Many places I ride haven’t enough 
cellular coverage to provide continuous information. Don’t put your eggs in one 
basket as the consequences increase. Missing a turn in your own town is one 
thing but losing your way when circumstances have become more critical is 
another. 

I navigate the GAP trail by cyclometer using a crude set of mileage cues and 
related locations I tape to my water bottle. I am continuously aware of where I 
am along my travels, even in the dark zones to both cellular service and 
satellite by obscured overhead radio visibility. The trail is an unmistakable 
linear feature across a map(s). At those incremental trailheads or landmarks I 
can find support needs or services from a map or by phone as coverage usually 
exists at those locations. I don’t need to be running either my phone or a GPS 
for my continuous location that way. It even shows on Google maps so I don’t 
need much more complexity or paid services for accurate location 
identification. 

Andy Cheatham
Pittsburgh

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