GPS signals are received with low power, comparable to the power received from a 60W light bulb located more than 20 000 km away from the surface of the earth. Due to this low power, GPS signals are highly susceptible to RFI from any source located near an aircraft emitting in the GPS L1 frequency band (1575.42 MHz +/-10 MHz).

Intentional GNSS RFI is divided into two major categories: GNSS Jamming and GNSS Spoofing.

Type of radio frequency interference that degrades the GNSS reception capability. The GNSS data used by the aircraft systems can be degraded or lost.

Type of radio frequency interference with emissions of GNSS-like signals that may be acquired and tracked in combination with or instead of the authentic signals. This can result in erroneous GNSS data used by the aircraft systems.

The majority of GNSS RFI events recently observed in-service result from military Electronic Warfare activities in conflict zones or related to the testing of such capabilities. The affected areas are often identified via NOTAMs informing flight crews to expect interference when operating in these areas. However, if  such military RFI activities are not identified or communicated in advance, aircraft may be exposed to jamming, spoofing, or both without prior notice.

Another major source of RFI is the implementation of security measures for sensitive sites and Very Important Persons (VIPs) intentionally interfering with GNSS to counter Unmanned Aerial Vehicles (UAVs). Affected areas typically include airports, locations with dignitaries or political figures, and correctional facilities.

Personal Privacy Devices (PPDs) intentionally jam GNSS receivers in close proximity, aiming to make tracking devices ineffective. These devices have caused significant operational disruptions at airports when activated in the airport’s vicinity.

GNSS repeaters receive the authentic GNSS signals and re-broadcast (“repeat”) them to enable reception inside buildings, where the GNSS signals would be otherwise masked. If GNSS repeater emissions are not properly managed, they are equivalent to GNSS spoofing, possibly impacting aircraft operating in the vicinity of the repeater.

There are many direct or indirect users of the GNSS data inside an aircraft. Depending on the aircraft type and the system architecture, the effects of GNSS interference may differ.

(fig.2) Simplified view of the main users of GNSS data on Airbus Aircraft (except A220)

(fig.3) Simplified view of the main users of GNSS data on A220 aircraft

While GNSS plays a major role in the aircraft positioning system, Airbus aircraft are designed to be robust against the loss of GNSS signals. The use of other data sources (IRS, VOR, and DME) enables the aircraft systems to maintain a position computation capability. A loss of GNSS inputs does not result in a map shift or  erroneous position computation by the Flight Management Systems (FMS). 

In the case of a loss of the GPS signal:

• A300, A310, A320 family, A330, A340, A350, and A380 aircraft:  The FMS (or ADIRS on A350 aircraft) switches from the mixed GPS/IRS position to an IRS-DME/DME position, or IRS-VOR/DME, or pure IRS, in order of priority. 
• A220 aircraft: The FMS switches from the onside GPS to the other side’s GPS position, or DME/DME, or VOR/DME, or blended IRS, up to Dead Reckoning, in order of priority. 

When GPS data is lost, the aircraft position performance may be degraded resulting in an operational impact on Performance Based Navigation (PBN).

In the case of GNSS spoofing, the FMS (or ADIRU depending on the aircraft configuration) may not detect that the signal is erroneous, leading to erroneous aircraft position that can be associated to:

• Unexpected aircraft turn in NAV mode with autopilot engaged
• Map shift on the Navigation Display 
• Abnormal IR drift information on the POSITION MONITOR page.

In addition, on ground, A300-600 aircraft with EPIC, A320 family, A330, A340, and A380 aircraft may auto-align their IRS to an erroneous GNSS reference.

A350 aircraft position has better robustness against GNSS spoofing due to  position hybridization based on both MMR sources and additional position monitoring. In most spoofing events reported to Airbus on A350 aircraft to date, the ADIRU rejected the erroneous GNSS position. However, erroneous aircraft position computation may still occur. At the time of writing the article, one case of erroneous position computation has been confirmed on A350.

On ground, A350 aircraft may also be affected by an automatic IRS alignment to an erroneous GNSS reference.

A220 aircraft can also be affected by erroneous position computation in a spoofing area. The FMS uses GPS as the primary position source. In spoofing conditions resulting in large position shifts, the FMS may reject navaid and IRS positions, leading to an FMS in Dead Reckoning mode.

Additionally, on ground, IRS may also align on an erroneous GNSS reference.

Many surveillance functions rely directly on GNSS information. As a consequence, if the GNSS signal is lost, the function may become unavailable. This includes the following (if functions are installed):

• Predictive Terrain Awareness and Warning System (TAWS)
• ADS-B out position reporting
• ADS-B in Air Traffic Situational Awareness (ATSAW), if installed
• Runway Overrun Prevention System (ROPS) 
• Altitude Setting Monitoring (ALTSM)
• TakeOff Surveillance (TOS2) or Takeoff and Landing Awareness Function (TLAF) on A220 aircraft.

An erroneous GNSS position/altitude may trigger spurious alerts from the following surveillance functions: Predictive TAWS, ROPS, ALTSM, and TakeOff Surveillance (TOS). In addition, the ADS-B position reporting may be erroneous.

On A300, A310, A320 family, A330, A340 aircraft equipped with Honeywell EGPWS, or A350, or A380 aircraft, radio altimeter rejection may be caused by an unsuccessful check of its reasonableness, in some specific erroneous GNSS altitude conditions. This results in the loss of the reactive TAWS. Additionally, on A350 and A380 aircraft, this rejection causes the loss of the TCAS and predictive windshear.

Weather radars that use GNSS data (A300-600 EPIC radar, WXR 2100A, RDR-4000, and A350 & A380 AESS) can experience display anomalies due to GNSS spoofing. In automatic mode, the terrain database is used to filter ground echoes from the radar display. Consequently, an erroneous position and/or altitude caused by spoofing can lead the radar to misinterpret weather echoes as ground echoes. This results in their removal, or conversely, the display of ground echoes as weather echoes.

On aircraft equipped with the Weather Hazard Prediction Function, undue hazard prediction icons may be displayed on the ND. Similarly, undue WEATHER AHEAD messages may be displayed on the ND on radar equipped with the function. 
In the case of position jumps, the weather radar function may be lost on A350 and A380 aircraft due to an AESS-internal limitation of handling such jumps.

(table1) Summary of surveillance effects.

The table below summarizes the effects that have been identified on communication systems. For more details, the flight crew should refer to the FCOM.

(table2) Summary of communications effects

A dedicated FCOM section provides the procedures to be applied before, within and after a GNSS interference area.

Airbus published troubleshooting tasks specifically designed to address GNSS RFI events. It is recommended to perform these tasks after exposure to GNSS interference to clear persistent effects and confirm that system anomalies were indeed caused by GNSS RFI, rather than by a different type of failure.

Airbus published training recommendations for GNSS interference in the FCTS Annex “Manufacturer Data for EBT” (OTT 999.0027/25 Apr 2025) of all aircraft except A220. 

To avoid the risk of negative training, Airbus does not recommend using GNSS Interference scenarios that may lead to undue TAWS alerts in the simulator.

Airbus is actively participating in industry efforts to address the GNSS interference phenomenon. Ongoing developments include:

As a first step, Airbus is developing a capability to automatically report entry and exit of RFI zones using ACMS and FDM data. The reported data will be shared with flight crews for flight preparation and in-flight awareness.

As a second step, enhanced IRS capable of detecting GNSS spoofing will be implemented, offering enhanced performance to maintain a guaranteed level of navigation service.

In parallel, the development of enhanced receivers, enhanced antennas, and computer standards is ongoing to improve resilience to GNSS interference. This will lead to a reduction in nuisance alerts, minimize the chance of losing surveillance functions, and decrease the likelihood of persistent adverse effects.

As a third step, the industry is progressing on authenticating GNSS signals and messages to prevent undetected spoofing. Suppliers are also working on developing GNSS receivers capable of spoofing detection, which prevents the transmission of erroneous signals to the aircraft systems.

Airbus regularly updates the FCOM and ISI articles concerning GNSS interference with the latest available information and recommendations. Operators are advised to regularly check these resources for updates. Furthermore, Airbus organizes regular webinars to communicate the latest information.