This paper supersedes IFALPA 21POS07, of the same name.
Modern air traffic relies heavily on the internal accuracy of aircraft systems and the aircraft’s ability to monitor its own reliability. Satellite-based Communication, Navigation and Surveillance (CNS) services have been playing a growing part in the overall ATM system and aircraft are becoming more reliant on space-based signals.
The accuracy achieved by these signals enables aircraft to perform instrument procedures without the need to rely on ground-based navigational aids, facilitates the reduction of separation by ATC, and helps optimize airspace capacity. Many aircraft navigation and warning systems rely heavily on accurate position.
In recent years, however, thousands of occurrences of partial or complete loss of these signals have been reported by pilots in different regions, with interruptions generally lasting 10 to 20 minutes.
Reasons for Signal Loss
Satellite signals are, by nature, very weak when they arrive at the receiver. They are therefore vulnerable to interference, natural or artificial, intentional (including jamming and spoofing) or unintentional (malfunctions).
In many cases, en-route signal interference has been linked to military operations. There has been a sharp increase in the proliferation of interference-capable equipment including incorrectly operated GNSS repeaters, miss-operated test equipment, and the foreseeable proliferation of sophisticated jamming and spoofing devices in the future. Personal Privacy Devices (PPDs) for example, designed to jam GNSS signals around them, can also interfere with aircraft or airport Ground-Based Augmentation System (GBAS) and ADS-B ground stations at close distance.
International Recognition of the Problem
These very serious concerns were raised once again at the 41st Session of the ICAO Assembly through 3 different papers:
WP/97, presented by Czechia, provided information on a growing number of occurrences of GNSS interference and called for further action. This paper led to the adoption of ICAO Assembly Resolution 41-8C on “Ensuring the resilience of ICAO CNS/ATM systems and services.”
WP/196 , presented by the UAE, expressed strong concerns regarding ongoing harmful interference to GNSS and invited the Assembly to urge States to adopt and implement measures to manage and reduce the impacts of such anomalies, as suggested in the ICAO Doc 9849, the GNSS Manual.
WP/198, presented by Japan, reported on activities aiming to mitigate GNSS vulnerabilities and stressed the importance of monitoring and reporting GNSS interference, and maintaining air navigation services to the maximum extent possible, in the event of a GNSS signal outage.
Position
IFALPA and IFATCA fully concur with the concerns expressed in these three WPs and support the recommended actions. In addition, IFALPA and IFATCA believe that the following aspects should be addressed as a matter of urgency:
For the effects of GNSS interference on aircraft and mitigation measures, see 23ADOBL01 – Manipulated GNSS Signals.
Download the IFATCA-IFALPA Joint Statement on GNSS Outages here.
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