Global Navigation Satellite System Outage

John Franklin • 6 November 2023
in community Air Operations
1 comment

Following EASA analysis of recent data from the Network of Analysts and open sources that has concluded that GNSS jamming and/or spoofing has shown further increase in the severity of its impact, as well as an overall growth of intensity and sophistication of these events, the Agency has updated the SIB on Global Navigation Satellite System (GNSS) Outage and Alterations Leading to Navigation / Surveillance Degradation.

The SIB (2022-02) was first published on March 17, 2022 and then updated to Revision 1 (R1) on February 17, 2023. You can access this Revision 2 that has been published today, on the EASA SIB Tool.

This revision includes the information outlined below (the main updates from the previous version are also highlighted).

Also download our information poster at the bottom. 

GNSS Jamming

Examples of symptoms of suspected GNSS spoofing for aircraft

These are the things pilot’s might observe while flying due to spoofing (no changes).

-              Incoherence in navigation position, such as GNSS/FMS position disagree warnings; 

-              Abnormal differences between Ground speed and True airspeed;

-              Time shift;

-              Problems with INS/IRS.

The list of the most affected flight information regions (FIR)

No changes, the list is as follows:

-              The Black Sea area:

-              FIR Istanbul LTBB, FIR Ankara LTAA

-              Eastern part of FIR Bucuresti LRBB, FIR Sofia LBSR

-              FIR Tbilisi UGGG, FIR Yerevan UDDD, FIR Baku UBBA

-              The south and eastern  Mediterranean area, and the Middle East:

-              FIR Nicosia LCCC, FIR Beirut OLBB, FIR Damascus OSTT, FIR Tel-Aviv  LLLL, FIR Amman OJAC, north-eastern part of FIR Cairo HECC

-              FIR Baghdad ORBB, north-western part of FIR Tehran OIIX

-              Northern part of FIR Tripoli HLLL 

-              The Baltic Sea area (FIRs surrounding FIR Kaliningrad UMKK):

-              Western part of FIR Vilnius EYVL, north-eastern part of FIR Warszawa EPWW, south-western part of FIR Riga EVRR

-              Arctic   area:

-              Northern part of FIR Helsinki EFIN, northern part of FIR Polaris ENOR

Examples of issues that a degradation of GNSS signal (including Satellite Based Augmentation Systems (SBAS) and Ground Based Augmentation Systems (GBAS)) could generate.

These are the problems this could cause to the safety of the flight – SIB revised to extend its applicability to aircraft and equipment manufacturers and address the cases of spoofing.

-              Temporary or non-recoverable failure or degradation of PNT information provided by GNSS possibly resulting in:

-              Inconsistent flight guidance possibly resulting in route deviations, uncommanded turns, and potential airspace infringements;

-              Loss or misleading surveillance system (e.g. corrupted Automatic Dependent Surveillance-Broadcast (ADS-B), TAWS (e.g., false PULL UP alert triggered by TAWS during cruising phase), wind shear, terrain and other surface functionalities);

-              Loss or misleading time dependent systems (e.g. clock, fuel computation system, flight management system);

-              Inconsistent, potentially misleading aircraft position, and ground or wind speed on the navigation display.

-              Inability to use GNSS for navigation, including waypoint navigation;

-              Inability to conduct or maintain GNSS based Area Navigation (RNAV) and/or required Navigation Performance (RNP) operations.

Recommendations for CAAs, ATM/ANS providers and Air operators (including helicopter operators – with specific information on both jamming and spoofing that flight crews and relevant flight operations personnel should be aware of)

CAAs should:

-              Ensure that contingency procedures are established in coordination with ATM/ANS providers and airspace users, and that essential conventional navigation infrastructure, particularly Instrument Landing Systems, are retained and fully operational;

-              Implement appropriate and proactive mitigating measures as a matter of high priority, including the issuance of NOTAMs, e.g. describing affected areas and related limitations (as appropriate and determined at State level).

-              Facilitate the establishment by ATM/ANS service providers of a process to collect information on GNSS degradations, in coordination with the relevant National Telecommunications Authorities, and promptly notify the related outcomes to air operators and to other airspace users;

-              Initiate discussion at a national level to restrict the usage of GNSS jammers;  

-              Confirm that contents of this SIB are duly considered by air operators, including helicopter operators, ATM/ANS providers, and aircraft and equipment manufacturers.

ATM/ANS providers should:

-              Establish a process to collect information on GNSS degradations, in coordination with the relevant CAAs, National Telecommunications Authorities, and promptly notify the related outcomes to air operators and to other airspace users;

-              Assess the impact of loss or anomalies of GNSS-based timing on CNS systems;

-              Issue NOTAMs to provide relevant information to airspace users (as appropriate and determined at State level);

-              Provide reliable surveillance coverage that is resilient to GNSS interference, as well as maintain essential conventional navigation infrastructure operational (Instrument Landing Systems, Distance Measuring Equipment (DME), Very High Frequency omnidirectional range (VOR)) in support of conventional navigation procedures;

-              Ensure that their contingency plans include procedures to be followed in case of large-scale GNSS jamming and/or spoofing events.

-              Monitor the traffic closely to prevent any deviation from the flight track/route.

Air operators, including helicopter operators, should:

-              Ensure that flight crews are aware of and trained on the importance of prompt reporting by means of a special air-report (AIREP) to air traffic services of any observed interruption, degradation or anomalous performance of GNSS equipment or related avionics (e.g. map shifts, suspected GNSS spoofing, position and duration of the GNSS interference);

-              Evaluate different scenarios based on their operations in order to provide the flight crew with timely information to increase awareness of jamming and spoofing;

-              Ensure that GNSS outage or spoofing topic is included in the flight crew ground recurrent training, highlighting the identified operational scenarios to recognize, react in a timely manner to different jamming and spoofing cases;

-              Assess operational risks and limitations linked to the loss of on-board GNSS capability, including any on-board systems requiring inputs from a reliable GNSS signal;

-              Ensure that operational limitations introduced by the dispatch of aircraft with inoperative radio navigation systems in accordance with the Minimum Equipment List, are considered before operating an aircraft in the affected areas;

-              Ensure, in the flight planning and execution phase, the availability of alternative conventional arrival and approach procedures (e.g. an aerodrome in the affected area with only GNSS, including augmentation, approach procedures should not be considered as destination or alternate).

-              If subject to FDM requirements and necessary data are available, use FDM programme to identify and assess GNSS spoofing events.

-              Concerning spoofing: contact aircraft or equipment manufacturers for instructions on how to deal with spoofing cases of their products and apply them.

GNSS jamming specific recommendations for Air operators, including helicopter operators:

Ensure that flight crews and relevant flight operations personnel:

-              Are aware of possible GNSS jamming ;

-              Verify the aircraft position by means of conventional navigation aids when flights are operated in proximity to the affected areas;

-              Check that the navigation aids critical to the operation for the intended route and approach are available;

-              Remain prepared to revert to a non-GNSS arrival procedure where appropriate and inform air traffic services in such a case; and

-              Report (AIREP) to air traffic services any observed irregularities.

GNSS spoofing specific recommendations for Air operators, including helicopter operators:

-              Ensure that flight crews and relevant flight operations personnel:

-              Are aware of possible GNSS spoofing;

-              Continuously monitor aircraft position using non-GNSS navaids and all available automatic navigation accuracy calculations, including the Estimated Position Uncertainty (EPU) figures.

-              Monitor the GNSS time versus non-GNSS time sources.

-              Closely monitor the ATC Frequencies in the vicinity of spoofing area. 

-              Apply the manufacturer’s instructions for the aircraft type on dealing with suspected spoofing, non-exhaustive list of examples of possible instructions could be such as:

  1. being ready to select HDG mode and manually adjust the flight course.
  2. being ready to ask for verification vector from ATC as long as needed.
  3. being ready to crosscheck with and switch to using alternate PNT such as IRS and/or available ground facilities (Multi-DME and VOR/DME).
  4. being ready to exclude the GNSS signals within affected area.
  5. being ready to disable automatic INS/IRS updating

-              report (AIREP) to air traffic services any observed irregularities.

 Aircraft and equipment manufacturers, should:

-              Support Air operators, by providing instructions to follow on how to deal with suspected GNSS spoofing events, when using their products.

Air operators are also reminded to report the suspected GNSS alterations and higher risk jamming occurrences to aircraft manufacturers and support their investigations by providing relevant information according to Regulation (EU) No 965/2012, ORO.GEN.160 (b).


Comments (1)

Tom Velkeneers

Hi John,

with the increase of GNSS manipulation (jamming, spoofing). Is there any consideration being giving to implementation of "Commission Implementing Regulation (EU) 2018/1048 of 18 July 2018 laying down airspace usage requirements and operating procedures concerning performance-based navigation". Especially past 2030 with the withdrawal of conventional navigation aids/NPAs/SID/STAR. At this moment we already see issues for example at Gdansk where RW11 only has RNP or VOR available with significant GPS interference occasionally requiring a tailwind approach to the ILS runway which increases exposure to runway excursion events. Especially on a contaminated runway. The regulation considers "Establishment of emergency measures in case of the non-availability of the GNSS signal" however this would most likely just lead to a diversion to a CAT 2/3 available location since jamming can blanket a wide area and can be unpredicable.

Kind regards,

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