Real GPS Outage

One has only to monitor the GPS NOTAMs to conclude that our near-100 percent confidence in GPS is misplaced. Here’s a story of a real GPS outage.

lbencini-tibo

Tuesday, November 28, 2023 at 08:00 AM ET

Verified

Key Takeaways:

A localized GPS anomaly at an airport, affecting multiple aircraft, was traced to an always-on re-radiating GPS test system in a maintenance hangar, exacerbated by a temporary second unit.
The incident highlights the critical importance for pilots to be prepared to navigate without GPS, urging proficiency in traditional VHF navigation methods and pre-flight integrity checks.
The author advises against removing VHF navigation capabilities during aircraft panel upgrades, especially for IFR operations, due to the potential for GPS unreliability.

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Routinely, my two GPS navigators will lock onto GPS satellites within a few minutes once powered up. But not this time. Both indicated LOI (loss of integrity), implying that the GPS satellites were insufficient. This was confirmed when no satellites appeared on the GPS Status pages. With the failure in two separate units, a failure in the airplane was unlikely. I suspected some systemic GPS problem.

Curiouser and Curiouser

Once I taxied perhaps 100 yards beyond the FBO, the satellites came alive one-by-one. Since I remain well practiced in VHF nav, and it was a local flight, I continued.