Tel: +47 75585000
Fax: +47 75585005
Civil Aviation Authority
- Norway -
P.O. Box 243
NO-8001 BODØ
11 MAR

Carriage and operation of SSR Mode S Airborne equipment in european airspace

Modification of Transition Arrangements


This AIC, covering IFR flights as General Air Traffic (GAT), provides information on an extension to the published transitional arrangements for the carriage and operation of Mode S airborne equipment in the airspace of Belgium, France, Germany, Luxembourg, the Netherlands, Switzerland and the United Kingdom. It is the outcome of an agreement reached between EUROCONTROL and the State authorities to modify the final dates for aircraft compliance.

1.2 This circular amplifies, and should be read in conjunction with AIC-I 04/03.Additional material can be found in the Joint Aviation Authorities (JAA) Temporary Guidance Leaflet (TGL) 13, Revision 1 Certification of Mode S Transponder Systems for Elementary Surveillance and NPA 20-12a, ACJ20X11, Enhanced Surveillance (or latest issue).

1.3 Norway has presently no plans to introduce MODE S surveillance within Norway FIR, but operators should observe the requirements laid down by states mentioned in this AIC, and also requirements in relation to ACAS II phase 1 and 2.

1.4 The agreement to modify the transitional arrangements for the installation of Mode S airborne equipment is aimed at those aircraft operators who have experienced difficulties, beyond their control, to meet the previously published compliance deadlines. Therefore, it should not be seen as a general alleviation to delay installation plans for Mode S Elementary Surveillance. Consequently, operators are strongly encouraged to complete transponder retrofits at the earliest opportunity as no further exemptions will be possible, for whatever reason, beyond these final dates for aircraft compliance.

1.5 The existing transition period for compliance with Mode S Enhanced Surveillance in the notified airspace of France, Germany and the United Kingdom remains unchanged in principle. However, in order to ease the burden on aircraft operators faced with disproportionate retrofitting costs, the revised arrangements allow for up to 10% of an operator’s applicable Enhanced Surveillance capable fleet to delay compliance with the Mode S Elementary and Enhanced Surveillance airborne equipment requirements by a further 24 months.

1.6 Similar revised transitional arrangements, which have been published separately, apply to State aircraft.


2.1 Extensions to the transitional arrangements for the carriage and operation of Mode S Elementary Surveillance (ELS) airborne equipment by fixed and rotary wing aircraft for IFR flights as GAT in designated airspace are set out below.

2.1.1 For aircraft issued with a first certificate of airworthiness in an ECAC State, or elsewhere, prior to 31 March 2004, the final dates for compliance with ELS functionality are:

a) Mode S transponder. Where a Mode S transponder is already installed, it must comply with ICAO Annex 10 SARPS, amendment 77, as a minimum, with effect from 31 March 2007, but see also 3.2.2 below.

Note 1: Functionality must include SI-Code capability and, where ACAS II is installed, also RA Reporting capability.

Note 2: The installed equipment must be an approved Level 2, as a minimum, Mode S transponder compliant with JAA Technical Standard Order JTSO-2C112a, or an equivalent standard that is compliant with the relevant ICAO SARPS and which is acceptable to the certification authority.

Note 3: The final date will apply to aircraft that were subject to the first phase of the ECAC ACAS-II mandate and to any aircraft that has a Mode S transponder installed, for whatever reason.

b) Mode A/C Transponder. For the purpose of IFR flights as GAT, existing SSR Mode A/C transponders must be replaced by Mode S transponders, in accordance with Notes 1 and 2, above with effect from 31 March 2007, but see also 3.2.2 below.

Note: It is recommended that aircraft operators subject to the second phase of the ECAC ACAS II requirements combine their ACAS II installations with those of ELS so as to be compliant with effect from 31 March 2006.

2.1.2 Aircraft issued with a first certificate of airworthiness in an ECAC State, or elsewhere, on or after 31 March 2004 should already be compliant or, with immediate effect, be made compliant, with the requirements of Mode S Elementary Surveillance, in particular notes 1 and 2 of para. 2.1.1.

2.2 All aircraft with Mode S transponders installed must be capable of reporting Aircraft Identification (sometimes referred to as Flight ID), as specified in item 7 of the ICAO flight plan. Further details are contained in AIC-I 03/04 ‘ICAO 24-Bit Aircraft Addresses and Aircraft Identification Reporting’.

2.3 Operators of aircraft that are not subject to Enhanced Surveillance requirements, should note that unless an aircraft qualifies for special flight status, or is to be withdrawn from service, no exemptions from the requirements of ELS for IFR/GAT flights in Mode S designated airspace will be permitted after 31 March 2007.

Note 1: Special flight status refers to exemptions granted to aircraft operators for IFR/GAT flights conducted for the purpose of flight testing, delivery and for transit into and out of maintenance bases.

Note 2: Operators need not install Mode S Elementary Surveillance on aircraft that are to be withdrawn from service by 31 December 2007 (see explanation in the note to 3.5.3).


3.1 The requirements of Mode S Enhanced Surveillance (EHS) apply to IFR flights as GAT by fixed wing aircraft in the designated airspace notified by Germany and the United Kingdom with effect from 31 March 2005 and by France with effect from 31 March 2006 when:

  • The aircraft has a maximum take-off mass greater than 5,700 kg or a maximum cruising true airspeed in excess of 250 kt.

3.2 Modified Transition Arrangements

3.2.1 Operators of aircraft that have a first certificate of airworthiness in an ECAC State, or elsewhere, prior to 31 March 2005, who are experiencing genuine retrofitting difficulties, may apply for an exemption to delay ELS and EHS equipment installation in order to be compliant by 31 March 2007.

3.2.2 However, an operator, when faced with disproportionate costs in equipping an entire fleet by 31 March 2007, may apply for an additional exemption to delay ELS and EHS compliance for up to 10% of the EHS capable aircraft in his fleet, see 3.3, by a further 24 months, until 31 March 2009.

3.2.3 These modified transition arrangements have been coordinated with all European Mode S implementing States. Therefore, flights by aircraft so exempted should not incur any operational restrictions.

3.3 EHS Capable Aircraft

3.3.1 An aircraft is considered to be EHS capable if the full list of 8 Downlink Aircraft Parameters, set out below, can be supplied. Where the parameter ‘Track Angle Rate’ cannot be supplied, ‘True Airspeed’should be substituted. If these conditions cannot be met, the aircraft will be considered EHS non-capable and, upon application, granted an exemption.

Basic DAP Set
Alternativ DAP Set
BDS 4,0Selected AltitudeSelected Altitude
BDS 5,0

Roll Angle
Track Angle Rate
True Track Angle
Ground Speed

True Track Angel
Ground Speed
BDS 6,0

Magnetic Heading
Indicated Airspeed/Mach No.
Vertical Rate (Barometric rate of
climb/descend or baro-inertial)
Magnetic Heading
Indicated Airspeed/Mach No.
Vertical Rate (Barometric rate of
clim/descend or baro-inertial)
  True Airspeed (if Track Angle
Rate is not available)

Note 1: Indicated Airspeed and Mach No. are considered as a single DAP. If an aircraft can provide both, it must do so.

Note 2: Details are in JAA NPA 20-12a, ACJ20X11 (or latest issue), which can be accessed via under the link ‘Documentation’.

3.3.2 Mode S Transponder
To meet EHS requirements, an approved Level 2, as a minimum, Mode S transponder must beinstalled that is compliant with EUROCAE Document ED-73B, as specified in the Declaration ofDesign and Performance (DDP) of the transponder equipment.

3.4 EHS Non-Capable Aircraft

3.4.1 Operators of EHS non-capable aircraft registering with the EUROCONTROL Exemption CoordinationCell will be granted an exemption but are strongly encouraged to supply any of the listed DAPs that are feasible and therefore benefit from the Mode S services that are available. Transmitted DAPs are to comply with the requirements of JAA NPA 20-12a (or latest issue).

3.4.2 Exemptions granted to EHS non-capable aircraft, which must be ELS compliant by 31 March 2007 at the latest, will carry no time limit. Any new mandate that might apply to such aircraft for the supply of DAPs in the future will be subject to a minimum of 5 years notice.

3.5 Mode S Exemption Coordination Cell

3.5.1 A Mode S Exemption Coordination Cell (ECC) has been established in the EUROCONTROL Agency to manage, on behalf of the regulatory authorities of the Mode S implementing States, the registering of compliance with, and the granting of exemptions from, the airborne equipment requirements set out in this Circular.

3.5.2 The ECC can be accessed via the website address in 4, below. The email address is

3.5.3 As well as managing registration of compliance and exemption applications for the EHS capable and non-capable aircraft already described, the ECC will accept additional applications for exemptions from aircraft operators as follows:

a) For aircraft that are to be withdrawn from service by 31 December 2007.

Note In the context of Mode S airborne equipment requirements,‘withdrawal from service’ means an aircraft that is scrapped, sold, returned to the lessor or re-routed so as not to fly in Mode S notified airspace.

b) For flights conducted for the purpose of flight testing, delivery and for transit into and out of maintenance bases.

c) For IFR flights conducted by aircraft that need to operate only occasionally as GAT.

Note 1: The term ‘occasional’ in this context is considered to be an average total flying time of 30 hours annually per airframe for flights under IFR/GAT rules in Mode S Enhanced Surveillance airspace.

Note 2: Operators intending to apply for exemptions for flights operating under the conditions described in 3.5.3 c) shall be required to make a declaration in advance that their aircraft shall not exceed the ‘occasional’ criteria. This shall then be subject to compliance monitoring by the appropriate ATC authorities.

3.5.4 Operators of aircraft that are subject to the EHS requirements are required to:

? Apply to the ECC for an exemption and / or
? Declare that the aircraft is compliant to the ECC.

These submissions should be made by 30 June 2005, at the latest. Operators should subsequently inform the ECC of changes to the EHS compliance status or to the ownership of the aircraft.


Further information or guidance may be obtained from:

Luftfartstilsynet ved:
Underdirektør Geir Ingebrethsen , flysikringsseksjonen tlf. +47 907 56 044
Underdirektør Andreas Mourud, luftdyktighetsseksjonen tlf. +47 982 61 893
Flyoperativ overinspektør Oddbjørn Jensen, flyoperativ seksjon tlf. +47 982 61 719

More general information concerning SSR Mode S in the context of European Air Traffic Management (EATM) is available at the EUROCONTROL Website Address: