About

GPSIA Statement on

Disruptions to Global Navigation Satellite Systems

February 14, 2024

Washington, DC

The U.S. government, in partnership with other affected governments, must take additional steps to reassure the public that it takes threats to the Radionavigation-Satellite Service due to disruptions seriously and is actively addressing them.

Accepting the status quo is unacceptable, particularly when risks to public safety from jamming and spoofing GPS and other global navigation satellite systems (GNSS) signals are well documented and increasing. GPSIA urges the U.S. government to immediately accelerate technological, interagency, and diplomatic activities to ensure that pilots, mariners, and the flying public can rely upon interference-free GPS and other GNSS to arrive safely at their intended destinations.

We outline below immediate and near term steps.

The International Community, including Public Safety Officials, Has Expressed Concerns.

On January 25, 2024, the Federal Aviation Administration (FAA) issued a Safety Alert for Operators (SAFO), “Recognizing and Mitigating Global Positioning System/Global Navigation Satellite System Disruptions.” A SAFO “…alerts, educates, and makes recommendations to the aviation community” and can convey time-critical information.

The SAFO dated January 25, 2024, notes that GPS jamming and spoofing activities are occurring “…in and around conflict zones, military operation areas, and counter unmanned aircraft systems protection… pose a potential safety of flight risk to civil aviation.” The SAFO highlights the impacts of these disruptions, including “…potential loss of situational awareness and an increase of pilot and Air Traffic Control (ATC) workload issues.”

Air carriers and general aviators are particularly concerned with aviation risks posed by jamming and spoofing of GNSS. As a public safety organization, the FAA has ensured that redundant aviation navigation systems are in place to reduce risks to the public. These analog systems, while valuable, are not nearly as capable as GPS and other GNSS signals.

Similar concerns were contemplated during the most recent World Radiotelecommunications Conference, where Resolution 676 (WRC-23), “Prevention and mitigation of harmful interference to the radionavigation-satellite service in the frequency bands 1164-1215 MHz and 1559-1610 MHz,” was adopted. The WRC Resolution notes that the public depends on the Radionavigation Satellite Service (RNSS) for a multitude of aspects of daily life: “…RNSS is used for safety-of-life applications, for scientific applications and in many applications and devices around the world and across all sectors of the global economy, as described in Report ITU-R M.2458.” In Resolution 676 (WRC-23), the WRC resolved to urge administrations “to apply necessary measures to avoid the proliferation, circulation and operation of unauthorized transmitters that cause or have the potential to cause harmful interference to RNSS systems and networks ….” The WRC also called upon administrations to take actions to prevent and mitigate harmful interference affecting RNSS operations, including “encourag[ing] collaboration between spectrum regulators, enforcement authorities and RNSS stakeholders, in particular in the aeronautical and maritime domains ….”

Additional Context is Essential to Understanding the Risks from Disruptions.

As this Cybersecurity and Infrastructure Security Agency Insights publication notes, “Detecting interference can be challenging.” These additional points add context to this statement:

GPS is the most reliable global navigation satellite system and is used by military, civil, and commercial entities around the world.
While GPS is the focus of the SAFO, foreign GNSS signals are also being disrupted when transmitting signals to receivers located in the same affected geographic areas.
Disruptions to all GNSS may be unintentional or intentional.
All electronics-based systems are susceptible to jamming and spoofing.
Illegal and irresponsible jamming and spoofing activities are long acknowledged threats to GPS. In 2016, South Korea highlighted threats to the safety of aircraft and maritime vessels to the United Nations Security Council when North Korea began jamming and spoofing GPS signals in the region starting in 2010.
The GPS signals designed for military users and transmitted today are less susceptible to jamming and spoofing than the signals used by civilian and commercial entities.
The Defense Department’s GPS Modernization program, once fully operational, will provide between eight and 60 times greater anti-jam capabilities for military users.
The August 2023 “MOU between the Department of Defense and the Department of Transportation For the Civil Use of the Global Positioning System” indicates both Departments will “…[p]romote international acceptance for civil use of GPS and its augmentations and military use of GPS PPS with equivalent levels of safety and performance (or better) in civil airspace and maritime operations in commercial shipping lanes and seaports.” [Ed. Note: Precise Positioning Service is a standard that describes the performance of signals provided to receivers used by the military and key allies.]
Many GNSS-enabled receivers are designed to detect and “throw out” irregular signals before delivering information to customers and users.
Receivers that “hear” multiple signals transmitted in different frequencies within the Radionavigation Satellite Service spectrum can be more immune to interference.

What More Can the U.S. Government Do?

The U.S. government can and should take immediate steps to address risks to public safety and the global economy:

The Federal Communications Commission and the Department of Homeland Security must dedicate additional resources to monitor for and eliminate online and other sales of illegal GPS jammers and spoofers.
The Departments of State, Transportation, and Defense should coordinate a diplomatic response with affected nations that is commensurate with the seriousness of threats to public safety and the global economy.
International Trafficking in Arms Regulations should be revised to permit the export of Controlled Reception Pattern Antennas, consistent with a PNT Advisory Board recommendation. CPRAs are an effective means to build resiliency in GPS receivers against spoofing or jamming attacks.

Two of these measures are specifically urged upon administrations by WRC-23 in Resolution 676 (WRC-23).

Additional steps must be taken by the U.S. government to mitigate these disruptions:

With additional funding and direction, the Defense Department should upgrade the existing GPS ground station (known as OCS or AEP) to support the civil GPS mission, to include a more robust civil signal (L5) originally designed for aviation and used by many commercial receivers. To further important U.S. government missions, the OCS has already been upgraded to accommodate Contingency Operations for GPSIII satellites, M-Code Early Use, and incorporated cyber security protections due to schedule delays to the next generation GPS control station (OCX). The recent announcement that OCX will be delayed until July 2025 at the earliest, coupled with the concerns raised by the FAA and WRC, increases the urgency and primacy of upgrading OCS to support the civil GPS mission as soon as possible.
The U.S. government can allocate additional funding to the GPS Modernization Program to rapidly accelerate and put on orbit more robust satellite capabilities:
- Four GPSIII satellites are currently in storage and should be prioritized for launch. They will provide up to eight times greater anti-jam capabilities for military and other users authorized to receive PPS signals. These satellites also transmit L5, which can also improve public safety.
- GPSIIIF satellites will be equipped with a Regional Military Protection (RMP) capability, which provides up to 60 times greater anti-jam capabilities when operated in a specific region. While launching GPSIIIF satellites will also increase the numbers and types of signals available to civil and commercial users, these satellites bring additional capabilities that can improve public safety:
  - Offers a growth path for optical crosslinks to improve GPS constellation accuracy, integrity, resilience, and responsiveness.
  - Includes Search and Rescue (SAR) capabilities that enable detection and geolocation of user’s distress beacons.
  - Offers a Laser Retroreflector Array (LRA) used for independent orbit determination.
The U.S. government can also allocate funding to accelerate the deployment of an authentication protocol for GPS civil signals to enable receivers to authenticate signals for spoofing mitigation. While National Technology Satellite-3 is scheduled to launch in late 2024 and will test an authentication protocol, that timeline is not timely enough. The European Union’s Galileo Open Service Navigation Message Authentication is one example of such a service.