GPS testing prompts St. Louis, Mo., flight advisory

July 7, 2011

The FAA has issued a flight advisory for potentially unreliable GPS signals in the vicinity of St. Louis, Mo., from July 8 to Aug. 26 and from Aug. 29 to Sept. 19.

During testing, the GPS signal may be unreliable or unavailable within a 15 nautical-mile radius centered at 385535N/0902522W or the STL VOR 35.1-degree radial at 4.8 nm at Flight Level 400 and above, changing in area with decrease in altitude to 20 nm radius at Flight Level 250, 20 nm radius at 10,000 feet msl, 20 nm radius at 4,000 feet agl and 10 nm radius at 50 feet agl.

Pilots are encouraged to report anomalies to the appropriate air route traffic control center to help determine the extent of signal degradation. Please share your reports with AOPA.

Notams will be published at least 24 hours in advance of tests, but may change with little or no notice. Pilots are encouraged to check notams frequently for changes to operations in the area. Tests will be during any period within the stated times, the FAA said.

The testing schedule will be conducted in one-hour blocks, July 8 to Aug. 26 from 1130Z to 2200Z, and from Aug. 29 to Sept. 19 from 1130Z to 2200Z.