David Megginson writes: > We have to decide on the authority of each data point individually. > Anything that we get from the DAFIF or FAA data should stand as-is, > for example. For Robin Peel's data, we should fix things only when > there is a known problem.
The problem is that in my spot checking, DAFIF and FAA data always disagree, sometimes/often significantly. Usually neither set of localizer info brings you in over the threshold correctly. Robin auto corrects all the approaches for X-Plane so those by default should be considered "munged" ... but they are munged for X-Planes coordinate system. I don't know if either DAFIF or FAA could be considered "authoritative". We'd need to go stand on top of a few actual localizers with a differential gps to verify if one or the other is more accurate. I suspect that for both, the information is often not recorded to the tolerances we need in FlightGear to get the approach to line up perfectly. It's probably fine for chart making or the other anticipated uses. I'm guessing that when an ILS is installed, someone goes out and stands at the center of a runway with something equivalent to a VOR gauge (or maybe they park a real aircraft out there) and they have the person at the localizer end adjust the heading until the VOR needle centers. That's just a guess. What get's recorded and put into the DAFIFT/FAA data could be *much* cruder or error prone. Regards, Curt. -- Curtis Olson IVLab / HumanFIRST Program FlightGear Project Twin Cities curt 'at' me.umn.edu curt 'at' flightgear.org Minnesota http://www.menet.umn.edu/~curt http://www.flightgear.org _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
