GPS Jamming, Spoofing

Rarely do we have days without notice of deliberate GPS interference somewhere in the U.S., usually from the military. But that’s only one source of GPS errors.

BTeter

Wednesday, June 05, 2024 at 07:53 AM ET

Verified

A spoofing transmitter is typically identified because it is ground-based instead of space-based. (Drawing courtesy of GPSPATRON.)

Key Takeaways:

Modern WAAS GPS, while precise, is highly susceptible to errors from natural phenomena, unintentional or intentional jamming, and especially insidious spoofing that alters the apparent aircraft position.
Unlike jamming which blocks the signal, spoofing provides misleading navigational data, posing a more dangerous "significant challenge" to aviation safety, particularly noted in regions like Eastern Europe.
Pilots must actively prepare for these risks by conducting preflight checks, vigilantly monitoring GPS status for anomalies, being ready to operate without GPS, and promptly informing Air Traffic Control of any degradation.

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Modern WAAS GPS provides ILS-like precision position and guidance, which can be affected by natural ionospheric disturbances and unintentional or intentional jamming. Spoofing by altering the apparent WAAS GPS position is also a growing problem, particularly in Eastern Europe. It’s time we explored these GPS errors.

WAAS/GPS Fundamentals

The GPS satellites transmit their orbital data in a long extended-data stream. The time of arrival of the low-amplitude data stream from the satellite is critical in determining the aircraft’s position. The GPS satellites, owned by the Department of Defense, are not geostationary—they rotate around the Earth in low orbits. “WAAS satellites” are in geostationary orbits much higher than the GPS satellites.