PNT Timing & Synchronisation for Aviation Systems and Networks

PNT Timing & Synchronisation for Aviation Systems and Networks


GNSS is extensively used in aviation, notably for:

  • positioning and timing for on board navigation purposes;
  • timing and synchronisation for datalink communications (board to ground and viceversa);
  • timing and synchronisation on ground for Surveillance, Air Traffic Control (ATC) and communication networks.

GNSS time outages or unexpected anomalies may affect aviation systems and networks. The advent of multi-frequency multi-constellation GNSS time information may provide a more robust timing and synchronisation service in aviation. Yet, usage of time information from multiple GNSS is subject of research and is not yet standardised.
At the same time, other and independent timing sources may be available to back-up/complement the GNSS timing and synchronisation service, e.g. clocks, Low Frequency systems, Network Time Protocols (NTPs). Their usage may depend on various factors, mainly coverage area and phase of flight for the on board case, ground equipment for surveillance and communications.
According to aviation stakeholders, in order to progress towards a safer Air Traffic Control it is of high importance to:

  • perform an assessment of criticality of GNSS timing in aviation and role of non-GNSS complementary/back up timing sources;
  • identify innovative schemes involving various PNT sensors to improve robustness and security in the timing and synchronisation service for aviation systems and networks.

The objectives of the proposed activity are to:

  • assess the criticality of the use of GNSS time in aviation;
  • define and perform demonstration of innovative PNT concepts complementary to GNSS, in order to provide robust and secure timing and synchronisation services for aviation systems and networks.

The tasks to be performed will include:

  • a thorough review and description of the systems (and networks) in aviation using GNSS time on board and on ground;
  • identification of required timing and synchronisation performance for aviation systems and networks;
  • identification of the main threats / external factors that could affect specifically the usage of GNSS time;
  • identification of timing technologies/sensors (complementary to GNSS, e.g. national LF systems) that are used in aviation (separately on board and on ground) and meet the required timing and synchronisation performance;
  • a thorough review and definition of alternative timing technologies/sensors that could be used as a GNSS time back-up/complement in aviation systems and networks (separately on board and on ground);
  • definition of relevant use cases with relevant stakeholders to be considered for the provision of robust timing and synchronisation services in aviation system and networks ;
  • definition of innovative schemes with PNT sensors for each use case, with assessment of achievable performance, benefits and feasibility;
  • demonstration of PNT innovative schemes as defined above, through either simulation or other means to be proposed.

The results of the activity will provide:

  • development and demonstration of innovative and robust PNT schemes for timing and synchronisation in aviation systems and networks, on board and on ground, along with achievable performance and feasibility.
  • recommendations for aviation (CNS/ATM).

Data and results from other ESA activities will be duly considered, assessed and used, as well as from EC and GSA studies (e.g. ‘EGALITE’ project for definition of a GNSS timing service concept and Fundamental Element project on GNSS Timing Receiver for Critical Infrastructure).