This page discusses how stakeholders could mitigate a GNSS outage
ANSPs are encouraged to develop Reversion Scenarios and associated Contingency Procedures in the event of GNSS being unusuable in order to ensure compliance with Articles 3-6 of the PBN IR to meet applications specified for the three step target dates of 2020, 2024 and 2030 described in Article 7 of the PBN IR.
Therefore, EUROCONTROL has developed, in collaboration with stakeholders, a European GNSS Reversion/Contingency handbook for PBN operations. This handbook is not intended to be a definitive guide to contingency operations for PBN. Rather, it provides a set of planning considerations and questions that ANSPs and regulators may want to consider when planning contingency operations for GNSS reversion. The document is deliberately not too detailed as it is impossible to consider all eventualities. The overall objective of the handbook is to enhance understanding on the shared challenge of providing for GNSS contingency/reversion.
The European GNSS Reversion/Contingency Handbook for PBN operations (PBN Handbook No. 6) can be downloaded here.
A series of questions which would need to be considered for contingency operations in the event of a GNSS outage is detailed below. It should be noted that this is not an exhaustive list and individual states will have additional questions to be considered.
Probability of an outage?
How long and/or how wide the impacted area?
What systems can be impacted by the loss of GPS in terms of CNS?
(Refer to Appendix 1 for more detailed info on loss of services)
Can full operations be maintained? (Yes/No)
If No, what is the operational impact on current operations?
What level of future service is needed?
What is contingency operation airspace concept?
What current infrastructure exists to enable degraded operations?
Cost Benefit Analysis considerations:
Supplementary Considerations for pilots and controllers:
No CNS enabler single-handedly resolves all an aircraft’s technical challenges in flight. Whilst Communication, Navigation and Surveillance have historically been ‘separated’, primarily for safety and historical reasons, evolving systems are increasingly relying on the same key system i.e. GNSS.
In discussions about PBN, it often becomes evident that GNSS is used on several CNS systems, e.g. time-stamping of data transfers in message sets (COM), synchronisation of surveillance data processors (SUR), in some systems, Data Link (communication) timing (COM). These systems often have back-up timing sources or other reversion means. For back-up timing sources the GNSS being unusable is important where a longer problem will result in greater clock drifts. This abridged list makes it clear that GNSS is a common point, a shared resource for Communication, Navigation and Surveillance and that a GNSS being unusable has the potential to disrupt operations depending on how much GNSS provides the backbone of various C-N-S elements.
In terms of navigation, the European fleet and Navaid Infrastructure is well equipped: Europe is fortunate to have a rich DME infrastructure and over 90% of the ECAC fleet is equipped with DME/DME RNAV capability. Indeed, in major European hubs, 98% of the fleet is equipped with DME/DME positioning capability. What this suggests is that continuing navigation as ‘normal’ for a while, after GNSS becomes unusable, is often feasible, though this statement is not absolute.
Do you want to leave?