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ANSP Preparation for Emergency, Degraded modes of Operation and Unusual Situations

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Category: Safety Alert Safety Alerts
Content source: EUROCONTROL Safety Alerts EUROCONTROL

Safety Reminder Message

ANSP Preparation for Emergency, Degraded modes of Operation and Unusual Situations

Date: 24 February 2011 Safety Reminder Message.gif


A number of short-term, catastrophic failures of ATC system components e.g. Voice Communication Systems (VCS) and Flight Data Processing (FDP) at various European area control centres have occurred during recent months. In each case the ATC staffs have responded promptly and efficiently to ensure that safety was not jeopardised.

These successes serve as a useful reminder to other ANSPs of the value of being properly prepared to deal with emergency, degraded modes of operation and other unusual situations that might threaten the provision of safe air navigation services.


Provisions for dealing with emergency, degraded modes and unusual situations are covered by, inter alia, the following:

  • ICAO - Training Manual for Air Traffic Safety Electronics Personnel (ATSEP), Doc 7192. Advanced Edition 2009), Part E-2, Chapter 12 states, Consequently, the requirement to provide periodic emergency training for all ATSEP is necessary to…ensure a timely response to a major failure or emergency situation that could jeopardize air traffic safety.
  • EU - EC Regulation 1108/2009 Annex Vb, 4 (c ) states that an air traffic controller shall acquire and maintain the practical skills appropriate to exercise his/her functions. Such skills… shall cover… abnormal and emergency situations. It goes on to say at Annex Vb, 5 (a) (iv), the service provider shall establish and implement a contingency plan covering emergency and abnormal situations that may occur in relation to its services.
    • ESARR 5 Chapter requires controllers to undertake periodical refresher and emergency training.
    • Guidelines for the Competence Assessment of Air Traffic Safety Electronics Personnel says at para 8.2, Operational ATSEP should receive emergency/unusual situation training on a regular basis.
    • Guidelines for Contingency Planning of Air Navigation Service, Edition 2.0, Chapter 10 states, it is essential that operational controllers and supervisors and their engineering/technical counterparts can react instantaneously to emergency events and unusual situations.


Catastrophic failures of complete ATC systems (or parts thereof) are rare. Nevertheless, to maintain tolerable levels of safety during periods of abnormal operations (i.e. the ability to fail to safe), it is essential that personnel connected with the provision of ATS are properly prepared to cope with a full range of situations. Recent experience has identified a number of common success factors:

  • Strategies, plans and procedures to deal with emergency, degraded mode and contingency operations should be in place. These need to be regularly reviewed and tested/exercised against relevant operational scenarios, e.g. equipment failures, airspace closures.
  • Formal refresher/continuation training regimes help prepare controllers, technical staff, supervisors and managers.
  • Controllers must have a basic awareness and understanding of the main ATC system components, their functionalities and limitations. Equally, engineering and technical staff must have an appreciation of the operational impact of system disturbances - intentional and unintentional. Teamwork across all disciplines is essential.
  • Swift communication (internal and external) is critical.
    • Inform neighbouring sectors (could be in another country) so that they can help relieve the situation if needed.
    • If necessary, inform the CFMU as early as practicable so that appropriate ATCFM regulations can be applied quickly and efficiently.
  • Letters of agreement, MoUs etc, checklists, emergency telephone numbers, standby facilities must be kept up-to-date if they are to be useful in potentially safety-critical situations.
  • In-built fallback capabilities improve overall ATM system resilience.
  • NSA oversight of contingency plans helps provide a focus on the investigation (severity and repeatability) and reporting of ATM Specific Occurrences as required by ESARR 2, Appendix A - 1.3.

Your Attention is Required

Air navigation services providers are invited to note the subject and share any relevant operational experiences concerning the issue described.

Further Information


© European Organisation for Safety of Air Navigation (EUROCONTROL) February 2011. This alert is published by EUROCONTROL for information purposes. It may be copied in whole or in part, provided that EUROCONTROL is mentioned as the source and to the extent justified by the non-commercial use (not for sale). The information in this document may not be modified without prior written permission from EUROCONTROL. The use of the document is at the user’s sole risk and responsibility. EUROCONTROL expressly disclaim any and all warranties with respect to any content within the alert, express or implied.