Mode S Exemptions

The National Aviation Authorities (NAAs) are responsible for granting exemptions, on an individual State by State basis.

Aircraft operators who require an exemption against the requirements of Mode S Enhanced Surveillance are to follow procedures published by individual NAAs and apply for exemptions from each of the Mode S implementing States within which flights are planned to take place.

Please note that exemptions previously granted by the Eurocontrol Exemption Coordination Cell (ECC) against the current Mode S mandates will remain valid provided that the terms and conditions of the exemption are respected and that the aircraft continues to be operated by the operator to which the exemption was granted. As exemptions are not transferable between aircraft operators it will be necessary for the new operator of a non-EHS capable aircraft to request an exemption from the NAAs of the Mode S implementing states in which flights will be conducted.

It is not necessary to declare aircraft as compliant with the requirements of Mode S Enhanced Surveillance.


In summary, exemptions against the requirements of carriage and operation of Mode S Enhanced Surveillance can be considered in the following cases but ONLY IF THE AIRCRAFT IS CERTIFIED COMPLIANT WITH THE REQUIREMENTS OF MODE S ELEMENTARY SURVEILLANCE:

  • Where the avionics equipage of aircraft do not permit the extraction and transmission of the full set of downlink aircraft parameters (DAPs).
  • For aircraft conducting flights, under existing rules, for the purpose of flight testing, delivery or for transit into and out of maintenance bases. These exceptional cases may be granted strictly limited duration exemptions. In recognition of the special nature of such requests they are processed via alternative locally managed channels:
  • -Test Flight: Aircraft operators seeking an exemption on the basis of conducting test flights (such as those test flights performed post manufacture but pre-delivery) are to contact their appropriate national aviation authorities for permission (contact details are provide in the 'Airborne Equipment - Requirements and Certification' section of this website).
  • -Delivery and Maintenance Flights: Aircraft operators wishing to conduct delivery or maintenance flights are to contact the NSA of those States from which an exemption will be requested providing full details of the aircraft, dates and the routes to be flown at least 5 working days before the flight is scheduled to occur. Please note that after 31 December 2008 the aircraft performing delivery or maintenance flights will be required to be ELS compliant.