GPS Interference Testing Encompasses Southwestern U.S.

A sweeping flight advisory issued this week advises "all aircraft relying on GPS" of interference testing across most of the Southwestern U.S. and the California coast throughout this month, and specifically warns operators of one light jet—the Embraer Phenom 300—to avoid the area entirely while tests are under way.

The first testing cycle took place yesterday, with further tests planned for on June 9, 21, 23, 28 and 30. Testing periods range from 1630Z to 2230Z (9:30 a.m. to 3:30 p.m. PDT), although the FAA notes the schedule may change without notice.

During the testing period, GPS signals may be "unreliable or unavailable" down to 50 feet agl along a 253 nm radius extending from China Lake, California., the FAA said. The disruption area swells at higher altitudes, ultimately encompassing a diameter of more than 950 nm at FL400 and enveloping all of California, Arizona and Utah, as well as portions of Oregon, Colorado and New Mexico.

Pilots should report any GPS anomalies to ATC during the testing period. Due to the type's unique geo-dependent flight stability systems, the agency also "recommends Phenom 300 pilots avoid the above testing area and closely monitor flight control systems due to potential loss of GPS signal."