At 04:37 07 August 2014, Ramy wrote:
Dan, you kidding about the accuracy of GPS, right? Or maybe
trolling? I
realize you may have never used a GPS in gliders, but I am sure
you've seen
GPS in cars which can pin point in which Lane you are traveling.
OK, I am
not going to fall into this trap.

Ramy


Most automotive GPS systems augment the raw GPS signal with a
'Lock to Road' function. If you have a route set they also often
assume you are traveling the route, so assume you will be and
display you in the correct lane.

You can see this in two ways... On my system if I choose to ignore
the guidance and take a different route the GPS shows me
travelling the the suggest route for a few seconds before snapping
to the new road. If you turn off the 'lock to road' function, it will
often show you several (or even tens) of metres from the road.

Using a modern ( and FLARM is not) GPS engine in an optimum
installation, raw GPS is still +-8m at 95% confidence and 16m at
99% confidence (Current US DoD stats)