On Thursday, August 7, 2014 1:30:14 AM UTC-7, Stats Watcher wrote:
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)

Isn't the Flarm GPS WAAS corrected? The WAAS standard of performance is 1.6M nominal horizontal (95%). When the NDGPS system is functional (and GPS engines take advantage of it) this will be reduced to 15 cm.