For a very brief interlude last week, aircraft flying near Dallas-Fort Worth International Airport (DFW) were subject to spoofing of their GPS-reported locations.
For many in the PNT community, the event evoked memories of a much longer, 44-hour disruption in that area in 2022.
For two minutes, between 11:47 and 11:49 local time on March 19, 12 aircraft reported false positions as a result of the interference. The incident was reported on the social media site LinkedIn. Both Benoit Figuet of SKAI Data Services, which operates the GPSwise advisory service, and Jeremy Bennington from Spirent, which offers the Watchman service, posted about the event.
Bennington was less specific about the time of the event but reported that it was to the west of DFW and had varying impacts on aircraft.
“Over the past 24 hours, we observed a GPS spoofing event to the west of DFW impacting multiple flights.” He cited eight flights from four airlines and commented that one had “brief low-integrity indications before and after,” another “lost GPS for the remainder of the flight,” and a third “experienced a loss of ADS-B without clear spoofing.”
“What stands out is the geographic consistency—almost all affected aircraft were on the west side of DFW, with only one instance on the east side,” he said.
“Even more interesting: Most aircraft maintained ‘good’ integrity indications. In more established interference zones, we often see integrity degradation before and after spoofing events. That wasn’t consistently the case here, which could make these events more difficult for flight crews to recognize and manage in real time.”
Bennington also discussed the impact to aviation safety.
“This is particularly concerning given the phase of flight. Interference during approach and departure introduces real safety risks, including the potential for false eGPWS alerts.”
Stanford University GPS experts Todd Walter, Zixi Liu and Sherman Lo observed that the “spoof to” location was near the center of effect, which had a greater than 50-mile radius. This “…also appears to be near Fort Wolters Range Control, a former Army base,” Walter said. He commented that Fort Wolters had been the site of DHS counter-UAS testing in the past.
Mitch Narins, president of Strategic Synergies and a former Chief Systems Engineer for Navigation at the FAA, said no advisories for exercises or tests had been posted for the day the spoofing took place.
This has led some to speculate the incident was the result of an accidental or unannounced use of a system that interferes with GPS reception as a way to deter or disable drones.
Department of Transportation (DOT) officials have been upgrading their ability to respond to such events since the 2022 incident. In this case, the Federal Aviation Administration (FAA) was immediately alerted by aviation users and the department quickly responded to ensure the problem source was identified and terminated.
