GPS Degradation in ZDC/ZNY areas

[Jay Somerset]

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)

[Jim]

http://www.fly.faa.gov/oisedit/gps_dod_sys.html
--
Jim Burns III

Remove "nospam" to reply


"Jay Somerset" > wrote in message
...
> 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)

[Jay Somerset]

On Sat, 29 Nov 2003 09:41:36 -0600, "Jim" > wrote:

> 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" > wrote in message
...
> 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)

[EDR]

> 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?