The Federal Aviation Administration released a flight advisory  Friday concerning more scheduled GPS interference testing in Alaska, this time based in Anchorage. From Aug. 18-20, GPS testing by the Department of Defense may result in unreliable or unavailable signals ranging outward from the city to 244 nautical miles and up to 40,000 feet.
Centered at 611451N/1495041W or the ANC VOR 014 degree radial at 006NM, the tests will affect the surrounding area as follows:
• Within a 244 nautical mile radius to an altitude of 40,000 feet and higher
• Within a 197 nautical mile radius to an altitude of 25,000 feet and higher
• Within a 132 nautical mile radius to an altitude of 10,000 feet and higher
• Within a 121 nautical mile radius to an altitude of 4,000 feet and higher
• Within a 97 nautical mile radius to an altitude of 50 feet and higher
Pilots are encouraged to report all GPS anomalies in the area during testing to Anchorage Center to assist in measuring the extent of signal degradation.
Notices to Airmen (NOTAMS) will be issued and updated throughout the testing period. Pilots flying through the area should check NOTAMS frequently as testing periods may change. The FAA advises that NOTAMS will be issued 24 hours in advance of all testing. The current scheduled times for the testing are as follows:
Aug. 18 - 20: 7:30 a.m. - 9:45 a.m.
Aug. 18 - 20: 1:30 p.m. - 3:59 p.m.
For more information on GPS interference testing, see the U.S. Coast Guard Navigation Center website . Contact information is available there  on a 24/7 basis for those with questions and concerns about the testing.
Contact Colleen Mondor at colleen(at)alaskadispatch.com .