The iPad can serve as an excellent backup navigator if your primary panel-mount GPS quits or if you have an electrical emergency. But here’s another scenario – what if the GPS signal became unavailable in the area you are flying? This rarely happens unexpectedly, but the FAA does do periodic testing of GPS which can result in unreliable or unavailable GPS signals in specific regions of the country.
The next testing session is scheduled for May 4 – 13, and centers around an area 70NM east of Jacksonville, FL (Centered at 302000N/0801000W or the CRG VOR 090 degree radial at 70NM). The testing period is scheduled for 2000Z – 0145Z each day, and the FAA says each event may last up to 45 minutes with 15 minutes off and may start at any time during the specified times.
The affected area spreads out like an upside down cone, affecting high altitude airspace as far as 332NM from the center point:
During testing, the GPS signal may be unreliable or unavailable within a 332NMR centered at 302000N/0801000W or the CRG VOR 090 degree radial at 69.6 NM at FL400 and above, decreasing in area with decrease in altitude to 283NMR at FL250, 210NMR at 10,000 FT MSL, 170NMR at 4,000 FT AGL and 127NMR at 50 FT AGL.
Pilots are strongly encouraged to report anomalies during testing to the appropriate ARTCC to assist in the determination of the extent of GPS degradation during tests.
The time periods discussed in this advisory may be reduced or cancelled with little or no notice. Pilots are advised to check NOTAMs frequently for possible changes prior to operations in the area. NOTAMs will be published at least 24 hours in advance of any GPS tests. When flying during the testing period in the affected areas, make sure to monitor your position with ground based navigation systems in addition to GPS.
Check out the official FAA Flight Advisory here.