Pilot Panics After GPS & ADS-B Failure — ATC helps the aircraft land safely

GPS and ADS-B Failure: When the Moving Map Disappears

A pilot experiencing simultaneous GPS and ADS-B problems can lose several of the electronic cues that have become routine in modern general aviation. In the incident associated with this report, the pilot became concerned when the navigation and surveillance picture degraded and turned to ATC for assistance.

GPS is not merely a display on a moving map. It can provide the position source used by navigation equipment and by ADS-B systems. The FAA notes that ADS-B Out depends on a position source and that a GPS or position-source failure can prevent the aircraft from broadcasting the expected surveillance information.

From the controller's perspective, an aircraft may therefore become harder to identify or track electronically at the same time that the pilot is losing the normal navigation presentation. That is why conventional headings, radar vectors and position reporting remain important backup tools.

The incident demonstrates the value of using ATC as an additional safety resource rather than treating electronic navigation as the only source of positional information. When the equipment becomes unreliable, a pilot can revert to basic navigation and accept vectors while troubleshooting or continuing toward a suitable destination.

The modern cockpit often presents navigation and surveillance information as a seamless picture, which can make a combined failure feel more dramatic than a conventional instrument failure. When GPS becomes unavailable, the aircraft may lose its primary position source. If ADS-B depends on that source, the surveillance picture can disappear at the same time.

The FAA explains that ADS-B Out relies on a position source and that a position-source failure can prevent the system from transmitting the required data. The agency also notes that pilots should know how their equipment annunciates failure rather than waiting for ATC to discover the problem.

In practical terms, the pilot can return to older methods: heading information, conventional radio navigation where available, dead reckoning, position reports and controller vectors. These methods are less visually convenient than a moving map but do not depend on the same single position source.

The ATC relationship is particularly valuable during the transition. A controller may still have radar or another surveillance source even when ADS-B is unavailable. That means the controller can provide headings and confirm the aircraft's position while the pilot works through the avionics problem.

The event therefore illustrates resilience rather than a failure of aviation technology. Electronic systems provide enormous benefits, but safe flight does not depend on every electronic layer remaining available simultaneously. Training, basic navigation skills and ATC support remain the fallback structure.

That resilience is particularly important because GPS and ADS-B are closely related in many modern installations. The FAA specifically notes that ADS-B position information can disappear when the underlying GPS or other position source becomes unavailable.

A pilot who understands the architecture is therefore less likely to interpret simultaneous annunciations as multiple unrelated failures. Instead, the symptoms can be recognized as connected to a common position-source problem, allowing the crew to select an appropriate fallback strategy.

“On 19 December 2025, Cherokee N3864M experienced an inoperative Mode C transponder and ADS-B failure while operating over Palo Alto Airport, CA (PAO / KPAO),”

Accident Facts

Sources

• Video source (ATC/audio reconstruction)
• FAA, Getting to Know Your ADS-B System.
• ICAO ADS-B implementation and operations guidance.
• Aviation incident record associated with the case.
• Video/ATC recording