Photo: Kevin Wells
Screenshot from video footage of the instrument panel inside a Cessna private jet. For a few seconds, the signals from GPS satellites were interrupted as the plane ascended after takeoff.

When Kevin Wells’s private jet lost its GPS reception on the approach to Hayward Executive Airport in California’s Bay Area in February 2019, he whipped out his phone and started filming the instrument panel. For a few seconds, the signals from over a dozen GPS satellites can be seen to blink off, before slowly returning as Wells continues his descent and eventually makes a safe landing.

Wells was quick to film the incident because this was not the first time he had suffered GPS problems. Less than a month earlier, his Cessna had been hit by a similar outage, at almost the identical location. “At that point it was pretty clear to me that it was either inadvertent or purposeful jamming,” he told IEEE Spectrum. “And I wanted to track it down.”