AirTalk.org Aviation discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  GPS Degradation in ZDC/ZNY areas          AirTalk.org Forum Index -> Aviators (General Discussions) View previous topic :: View next topic   Author Message Jay Somerset Guest Posted: Sat Nov 29, 2003 1:59 pm    Post subject: GPS Degradation in ZDC/ZNY areas Has anyone alse tried to use GPS in this area? Mine showed current location pretty accurate (within 1/4 mile) but indicated track wallowed +/- 20 degrees from actual. What sort of degradation tests are being run that wil affect GPS this way? No outages encountered, just misleading track information. Here is the NOTAM... ------------- GPS unreliable within a 270 nautical miles radius of 3050N/08025W at FL400. this area decreases with altitude to a CIRCLE of radius 225 nautical miles at FL250. then to a CIRCLE of radius of 160 nautical miles at FL100, down to a CIRCLE of radius 115 nautical miles at 4000 above ground level. IFR operations based upon GPS navigation should not be planned in the affected area during the periods indicated. these operations include domestic RNAV or long - range navigation requiring GPS. these operations also include GPS standalone and overlay instrument approach operations. 1600 - 2000/0000 - 0400 daily will be effective November 22nd, 2003 at 11:00 AM EST (0311221600) - December 16th, 2003 at 11:00 PM EST (0312170400) Back to top Jim Guest Posted: Sat Nov 29, 2003 3:41 pm    Post subject: Re: GPS Degradation in ZDC/ZNY areas http://www.fly.faa.gov/oisedit/gps_dod_sys.html -- Jim Burns III [email]jburns3 (AT) nospamuniontel (DOT) net[/email] Remove "nospam" to reply "Jay Somerset" <jay (AT) no-fixed-abode (DOT) com> wrote Quote: Has anyone alse tried to use GPS in this area? Mine showed current location pretty accurate (within 1/4 mile) but indicated track wallowed +/- 20 degrees from actual. What sort of degradation tests are being run that wil affect GPS this way? No outages encountered, just misleading track information. Here is the NOTAM... ------------- GPS unreliable within a 270 nautical miles radius of 3050N/08025W at FL400. this area decreases with altitude to a CIRCLE of radius 225 nautical miles at FL250. then to a CIRCLE of radius of 160 nautical miles at FL100, down to a CIRCLE of radius 115 nautical miles at 4000 above ground level. IFR operations based upon GPS navigation should not be planned in the affected area during the periods indicated. these operations include domestic RNAV or long - range navigation requiring GPS. these operations also include GPS standalone and overlay instrument approach operations. 1600 - 2000/0000 - 0400 daily will be effective November 22nd, 2003 at 11:00 AM EST (0311221600) - December 16th, 2003 at 11:00 PM EST (0312170400) Back to top Jay Somerset Guest Posted: Sun Nov 30, 2003 3:24 pm    Post subject: Re: GPS Degradation in ZDC/ZNY areas On Sat, 29 Nov 2003 09:41:36 -0600, "Jim" <jburns3 (AT) uniontel (DOT) net> wrote: Quote: http://www.fly.faa.gov/oisedit/gps_dod_sys.html The location in the NOTAM does not correspond to anything in the web page (above), and appears to be centered off the east coast of Florida in the ocean. Why then, is it NOTAM'ed for the DC and NY areas, which are way out of the posted range? "Jay Somerset" <jay (AT) no-fixed-abode (DOT) com> wrote Quote: Has anyone alse tried to use GPS in this area? Mine showed current location pretty accurate (within 1/4 mile) but indicated track wallowed +/- 20 degrees from actual. What sort of degradation tests are being run that wil affect GPS this way? No outages encountered, just misleading track information. Here is the NOTAM... ------------- GPS unreliable within a 270 nautical miles radius of 3050N/08025W at FL400. this area decreases with altitude to a CIRCLE of radius 225 nautical miles at FL250. then to a CIRCLE of radius of 160 nautical miles at FL100, down to a CIRCLE of radius 115 nautical miles at 4000 above ground level. IFR operations based upon GPS navigation should not be planned in the affected area during the periods indicated. these operations include domestic RNAV or long - range navigation requiring GPS. these operations also include GPS standalone and overlay instrument approach operations. 1600 - 2000/0000 - 0400 daily will be effective November 22nd, 2003 at 11:00 AM EST (0311221600) - December 16th, 2003 at 11:00 PM EST (0312170400) Back to top EDR Guest Posted: Sun Nov 30, 2003 4:30 pm    Post subject: Re: GPS Degradation in ZDC/ZNY areas Quote: The location in the NOTAM does not correspond to anything in the web page (above), and appears to be centered off the east coast of Florida in the ocean. Why then, is it NOTAM'ed for the DC and NY areas, which are way out of the posted range? Sunspots? 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