Military GPS jamming is disrupting US aviation – and it’s getting worse
A new report has revealed the scale of the impact of military jamming exercises on US commercial aviation – and shows it’s set to get worse unless industry and government act to address it.
A new report from the Radio Technical Commission for Aeronautics (RTCA) has highlighted the worsening impact of military GPS jamming exercises on commercial aviation in the US.
Commissioned by the Federal Aviation Authority (FAA), the March 2018 report, Operational Impacts of Intentional GPS Interference [PDF], reveals that the US Department of Defense is carrying out more jamming exercises every year, creating growing problems for airports and commercial airlines operating in the affected airspace.
Threefold increase in jamming exercises
The number of exercises has increased sharply, from 43 in 2012 to 127 in 2017, with the number of test locations increasing from 16 to 37. The aim of the exercises is to ensure US military operations can cope in conditions where GPS is unavailable, so they invariably involve the civilian GPS signal being jammed over wide areas of the United States.
I found those numbers very interesting, as they mirror the upward trend in pilots reporting GPS interference events to NASA’s Aviation Safety Reporting System (ASRS) database. When I examined those reports in 2016, I discovered that not only were there more interference events reported year on year, but that around 25% of them were specifically attributed to military jamming exercises.
Wide range of impacts on aircraft systems and ground operations
As the aviation industry comes to rely more and more on GPS for in-flight navigation, take-off and landing, it looks as though the impact of these jamming exercises will continue to grow.
The report lists 13 different potential impacts on commercial aircraft systems, ranging from loss of GPS-based navigation, which can result in missed runway approaches, to impairment of the ADS-B system, which reports an aircraft’s location to air traffic control and other aircraft nearby.
In several cases (24 in 2017), air traffic controllers have had to activate a so-called “stop buzzer” – a request to the organisers of the military exercise to pause the jamming so that a particular aircraft, such as an air ambulance, can take off or land unimpeded.
A threat to “next-generation” aircraft navigation systems
With the aviation industry implementing new GPS-enabled systems to allow faster, smoother landings, and relying more on ADS-B for situational awareness in crowded airspaces, interference to the GPS signal is set to cause more problems unless something is done to address the issue.
GPS-based navigation equipment is designed to allow more flights to land, in quicker succession, at busy airports. If GPS is unavailable, aircraft may have to wait longer to land and take off, or may have to “go around” and re-attempt a landing if the first approach is missed. That creates stress for flight crew and air traffic control, additional cost (in fuel) for airlines, and efficiency losses for airports.
The report notes that one airline has implemented a policy not to fly at all through affected airspace in areas where jamming is taking place, which must have a significant impact on operations. And one pilot filing a report to the ASRS in 2016 made their feelings very clear:
“The recent notice - NAFB 16-03 flight advisory GPS interference testing illustrates a continuous disregard for safety of our nation's airspace navigation system. The coverage area of this test effectively grounds all GPS-equipped aircraft in the Southwest flying IFR since they may experience unknown signal loss.
[…] At the time that ground based Navaids are being decommissioned and our government is promoting GPS based systems as primary navigation sources, the repeated interruption of GPS signals by our military [is] threatening the safety of our aviation system.”
How can the problem be solved?
The aim of the report was to understand the extent of the problem so that it can be addressed. The RTCA offers 25 recommendations on how government and industry can work together more effectively to ensure civil aviation can operate smoothly, and the military can continue to conduct vital exercises.
They include making improvements in three areas:
- The planning process for interference events
- The notification of interference events to pilots
- The alerting process during interference events
In addition, it calls for manufacturers and users of GPS-dependent equipment to better understand and mitigate against the impact of GPS interference on aircraft systems.
Understanding the risks
That last one is especially important given that military jamming exercises are just one of many scenarios in which GPS disruption can interfere with avionics and ground-based navigation systems.
Recently we’ve seen serious problems in the Philippines, with many aircraft experiencing GPS disruption on the approaches to Manila airport (attributed to a malfunctioning TV transmitter), and in the Eastern Mediterranean (likely due to signal jamming by parties involved in the Syria conflict). And just last month an Air France flight reportedly had to return to Munich Airport shortly after take-off, as both GPS systems on board failed.
The report highlights the needs for the whole aviation industry to understand the risks associated with GPS-based navigation, and to address any shortcomings in systems and procedures. A risk assessment is always the best first step, followed by testing in realistic interference scenarios (including testing with humans in the loop to uncover any unintended consequences), and the implementation of appropriate counter-measures.
Protect, Toughen and Augment
It’s worth keeping in mind the framework devised by Dr Bradford Parkinson, the father of GPS, who advised a continuous effort to “Protect, Toughen and Augment” both the Global Positioning System itself and the systems that depend on it. In the aviation domain, that could be applied as follows:
Protect: Issuing better, more detailed advisory notices before a known jamming event, providing ATC guidance and updates in real time during the event, and better co-ordination with the military. GPS interference detectors would also be very effective deployed around airports to detect the use of illegal civilian jammers. Detected interference events can then be reported to pilots and ATC. An analysis of collected data could lead to operational improvements and mitigations.
Toughen: Improving GPS sensors on aircraft to ensure better integrity monitoring and reduce Time to Alert, or using multi-constellation, multi-frequency receivers to reduce the impact of jamming on one frequency. Improved antenna design and placement could also help considerably.
Augment: Using other sensors or systems to complement or provide a backup to GPS navigation. Commercial aviation already has networks of conventional radio navigation aids and ILS landing systems, a worldwide infrastructure that can be used alongside GPS to provide assured navigation.
One last thought: this report is concerned with the impact on commercial aviation, but this isn’t the only industry that should be concerned about the impact of military jamming exercises. As more sectors of the economy come to depend on GPS, from agriculture to shipping, disruption to the GPS signal should be a major element of any risk assessment.
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System Design Engineer
6yIf this is going to happen-- and it needs to-- then frankly, the test site is the right place, because if you can't line up for McCarran, of all places, you need more training. Drive down Sunset and you will clearly see, at any hour of the day, five evenly spaced aircraft on final, all aimed at the most iconic, recognizable, and most importantly, _differentiable_ skyline on earth, in a city that almost never has anything other than perfect visibility. I will readily admit that I don't have anything other than a few flight hours and some simulator time, but it seems to me that this is about the safest place to get some "unexpected bonus training". I can understand that being seen as a flippant way to talk about a metal tube full of a few hundred civilians, but the writing is on the wall that GNSS disruption will be a very real part of future conflicts, and avoiding training both civil and military aviators for that does not seem wise.
Space Operations & National Security Professional | JCIDS/PPBE | Avid Skier | Proud Father
6yReport should read “Military ramping up efforts to do their part to prepare pilots for possible GPS outages or hacking.” Also, how many of these events could have been reported if the pilots had read the SPINS when filing their flight plan. Military exercises of this type are subject to almost unreasonable amounts of scrutiny and control, and must be planned months in advance. Do your job, and don’t forget how to fly just because you lose an electronic sensor.
infiniDome CEO
6yGreat article. One note though - you’d expect aviation’s n systems to adopt some level of anti-jamming / anti-spoofing solutions. These are no longer expensive large systems but come in minimal footprint without affecting payload and certainly easy on the price (e.g #GPSdome by #infiniDome)
Humanist & Solutionprovider for Mission Critical PNT, IoT and 5G Telecom Ctrl Cmd and Trusted Precise Wireless Timing, TPWiT.
6yAre there anything like "the civilian GPS signal"?! Here in Norway the Civil Aviation Authority has thrown out almost all of its working MSSRs (Monopulse Secondary Surveillance Aviation traffic RADARs) and now fully relies on WAM to do the job "for free" without being too worried or concerned that they're not in charge of 2 of the most important segments (Spacesegement& Control-segement) and transmission-channel of the NAVSTAR GPS timing solution which they put all their trust into. I guess they go for the slogan "don't worry, be happy". The Norwegian CAA collects all the airway-fees, but do not support their prime provider for their Timing of their WAM-solution. NAVSTAR GPS. C/A (Coarse Acquisition)signal) L1 also plays a vital role for EGPWS-solutions onboard almost any aircraft. Last year, servere manmade jamming detected by aircrafts made NAVSTAR GPS unavailable for several weeks in a greater northeast region of Norway, but this seems to have been ignored by the people in charge of flightsafety in Norway. A regional airliner in Norway has experienced a servere Timing-issue for almost more than a year now d/t firmwareproblem with their choosen flightmanagement (FMS) system, but choose to be quite about it, and to live with it, rather than to fix it d/t ageing fleet of aircrafts and potential additional typecertification (TSO) as it doesn't seem to impact the precision/accuracy of the system that is vital to other integrated operational functionalities like GBAS. The upcoming integration of Poseidon P8 which heavily relies on NAVSTAR GPS for its intended purpose will require a great deal to cope with an aggressive jamming-scenario, but time will show how successful an GPS-independent submarine-tracking-operation will turn out to be. The Norwegian Defense are also planning to demolish its coastal military RADARs and will rely more on AIS, microsatelliets and drones to carry out the required surveillance, so there's no lack of "technology-optimism" in Norway following the demolsihing of 4-four excellent, very low-cost, eLoran-stations during year 2016, 2017 and 2018. Time will show if the optimism will pay off in the long run as everything relies more or less on NAVSTAR GPS Coarse Acquisition L1 signal from above.. I'm very surprised to witness the unlimited trust a lot of people and major "businesses" put into a single signal.