Table of Contents. Mode-S Surveillance Decision 3 What is Mode-S? 3 How does Mode-S work? 4

The purpose of this Information Notice is to brief Military Organisations about regulation changes related to the mandatory carriage and operation of Secondary Surveillance Radar (SSR) Mode-S airborne equipment. Table of Contents Mode-S Surveillance Decision 3 What is Mode-S? 3 How does Mode-S work? 4 Mode-S Surveillance Deployment in Europe Why civilian ATC are implementing Mode-S? 5 Where will Mode-S be implemented? 6 Mode-S Elementary Surveillance 6 Mode-S Enhanced Surveillance 7 Mode-S Surveillance Exemptions Are there any exemptions 8 Mode-S Elementary Surveillance 8 Mode-S Enhanced Surveillance 8 Exemption Coordination Cell 9 Military Organisation, what do you have to do? As a Military Organisation, what do you have to do? 10 Check your Mode-S Transponders 10 Check your Airborne Equipment 11 Check your Sensor Equipment 12 Flight Crew Awareness Pre-flight 14 Pre-departure 15 In-flight 15 Military Controller Awareness What will you see? 16 Reference Material 18 Mode-S Programme Contacts 19

Mode-S Elementary Surveillance Decision On 7th April 2000, the Provisional Council of EUROCONTROL agreed to implement Mode-S Elementary Surveillance within the core area of Europe subject to high air traffic density. As mandated, by the participating States, Aircraft Operators are required to equip their aircraft with Mode-S airborne equipment that supports Mode-S Elementary Surveillance functionality. This includes Mode-S transponders with Surveillance Identifier code capability and the automatic reporting of Aircraft Identification in accordance with ICAO Standards and Recommended Practices (SARPs). What is Mode-S? Mode-S is an extension of current Secondary Surveillance Radar (SSR), which permits selective addressing of individual aircraft. Additional data may also be extracted from the aircraft, including aircraft identification corresponding to that entered in the flight plan. Mode-S operates on the same radio frequencies (1030 and 1090 MHz) as conventional SSR systems and is backwards compatible with Modes 3/A and C. [ Military Organisations Information Notice ] 3

How does Mode S work? Each Mode-S equipped aircraft is assigned a unique ICAO 24-bit aircraft address. Using the selective interrogation capability of Mode-S, SSR Mode-S Sensors are able to first acquire and then to selectively interrogate a specific aircraft via its unique ICAO 24-bit aircraft address, even in high-density situations. This significantly improves the ability of ATC to monitor and direct the aircraft, as well as the others around it. The innovation of Mode-S (Select) resides in the use of selective addressing of aircraft which offers technical advantages over conventional Secondary Surveillance Radar, such as reducing FRUIT and garble, hence providing higher integrity radar tracks. ICAO 24 bit Aircraft Address Selective interrogation Downlink Aircraft Parameters (DAPs) Mode S Transponder Secondary Radar SSR Mode S Sensor DLH655 A 1234 370 303-355 390 Headling Speed Selected FL Controller working position ATC Radar Tracker and Server DAPs ASTERIX Cat 34+48 Primary Radar Interrogator-Code 4 [ Military Organisations Information Notice ]

Mode-S Surveillance Deployment in Europe Why civilian ATC are implementing Mode-S? 1. SSR Radio Frequency (RF) Pollution Given the concerns over increasing Radio Frequency pollution and the inherent limitations of the current SSR system, it was felt necessary to move from conventional SSR to Mode-S. The predominant reason for upgrading from (SSR) Mode-A/C to Mode-S is to maintain the existing levels of flight safety. In the airspace subject to high air traffic density, SSR stations are reaching the limit of their operational capability. RF pollution is increasing and in the face of continuing traffic growth, it must be ensured that the probability of detection remains at an acceptable level. 2. Mode-A code shortage In the current SSR system, aircraft are identified using a discrete Mode-A code that is assigned by the ground system prior to take off and input by the pilot. There are only 4096 Mode-A codes available and, as traffic levels increase, it is becoming increasingly difficult to assign discrete codes within busy regions of airspace. [ Military Organisations Information Notice ] 5

Where will Mode-S be implemented? Civilian ATC authorities have commenced their implementation of Mode-S Elementary Surveillance in the airspace of Belgium, France, Germany, Luxembourg, the Netherlands and Switzerland. Mode-S Enhanced Surveillance will be implemented from 2005 onwards, initially in the airspace of France, Germany and the United Kingdom. Mode-S Area Differences concerning airborne equipment carriage for both Elementary and Enhanced Surveillance are explained in the following pages. Initial implementation EUROCONTROL, Member States, the State Regulatory authorities and the Airline Industry have determined a common timeframe for aircraft to be equipped. The compliance time scales are as follows: Mode-S Elementary Surveillance 1. IFR 1 Airborne Implementation For aircraft flying IFR as GAT 2, latest dates for the carriage and operation of Mode-S Elementary Surveillance airborne equipment in designated airspace are as follows: New production aircraft to be compliant by 31 March 2004 Completion of all aircraft retrofits by 31 March 2005 1- IFR refers to Instruments Flight Rules 2- GAT refers to flights conducted in accordance with the rules and provisions of ICAO 6 [ Military Organisations Information Notice ]

2. VFR 3 Airborne Implementation For aircraft flying VFR 3, latest dates for the carriage and operation of Mode-S Elementary Surveillance airborne equipment in designated airspace are as follows: New production aircraft to be compliant by 31 March 2005 Completion of retrofits by 31 March 2008, subject to individual State agreements. Mode-S Enhanced Surveillance Mode-S Enhanced Surveillance builds upon the benefits of Elementary Surveillance and consists of the extraction of additional airborne data in the form of Downlink Airborne Parameters (DAPs). This facilitates an increase in the safety and efficiency of ATM operations. The DAPs required are: Air Speed Ground Speed Magnetic Heading Roll Angle Selected Altitude Track Angle Rate True Track Angle Vertical Rate The carriage and operation of Mode-S Enhanced Surveillance functionality applies to aircraft with a maximum take-off mass in excess of 5,700 kg or a maximum true cruising airspeed in excess of 250 kts conducting IFR flights as GAT, with effect from 31 March 2005. A transition period of 2 years will be applied until 30 March 2007, during which a coordinated exemption policy will be applied. 3- VFR refers to Visual Flight Rules [ Military Organisations Information Notice ] 7

Mode-S Surveillance Exemptions Are there any exemptions? The granting of exemptions from the requirements for the carriage and operation of Mode-S airborne equipment in European Airspace has been co-ordinated with the participating States, in accordance with the provision of ICAO Doc 7030. Exemptions fall into the following categories: Mode-S Elementary Surveillance 1. VFR Flights conducted by Aircraft when the carriage of a transponder is impracticable, or, when an exception to the requirement is authorised for a specific purpose. 2. VFR and/or IFR Flights Flights conducted for the purpose of flight testing, or delivery, and transit into and out of maintenance bases. 3. IFR State Aircraft Flights conducted by State (military, customs, and police) aircraft that need to operate occasionally as GAT. Mode-S Enhanced Surveillance 1. Analogue and Part Digital Aircraft Where the avionics do not permit the extraction and transmission of the full set of DAPs. 2. Inability to Meet the Mandated Timescale Where Aircraft Operators show a clear intent to equip their aircraft as soon as practicable after 31 March 2005, but experience genuine technical issues or supply problems, causing delays that are beyond their control. This also applies to the wiring for Aircraft Identification that may constitute a Partial Alleviation from the Elementary Surveillance requirements. 8 [ Military Organisations Information Notice ]

3. Aircraft Retirement Where aircraft have an out of service date before 31 December 2007. 4. Special Flights Flights conducted under existing rules for the purpose of flight testing, delivery and for transit into and out of maintenance bases. 5. Occasional IFR Flights IFR flights conducted by aircraft that need to operate only occasionally as GAT. Exemption Coordination Cell An Exemption Coordination Cell will be established within the EUROCONTROL Agency to support the monitoring of the implementation of Mode-S Enhanced Surveillance and the coordination of exemptions among the participating States. The management and operation of the Cell will be conducted under the auspices of the EUROCONTROL Regulatory Unit. The exact date of operation of the Exemption Coordination Cell and the detailed procedures to be followed, will be agreed with the States participating in the Mode-S Enhanced Surveillance Programme and publicised in due course. [ Military Organisations Information Notice ] 9

Military Organisation, what do you have to do? As a military organisation, what do you have to do? Military Organisations will need to respect applicable regulations when flying in European Mode-S Airspace. The carriage and operation of Mode-S airborne equipment by military aircraft will facilitate handling in the airspace in which air traffic services based on SSR Mode-S are provided by ATS units. Check your Mode-S Transponders Military Organisations are required to equip their aircraft with Mode-S airborne equipment that supports Mode-S Elementary Surveillance, and where applicable Mode-S Enhanced Surveillance functionality. Onboard aircraft changes consist of the transponder upgrade/replacement and the necessary modifications required for the provision of the downlink Aircraft Identification Feature. Where a Mode-S transponder is already installed, it must comply, as a minimum, with the provisions of ICAO Annex 10, SARPS, Amendment 77 with effect from 31 March 2005. This standard of equipment had already been prescribed for the ECAC ACAS II implementation. The Mode-S transponder must be an approved level 2, as a minimum, 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 approval authority. The level 2 permits standard length datalink communication from ground to air and air to ground. It also includes Aircraft Identification. For the purpose of IFR/GAT flights, existing SSR Mode-A/C transponders must be replaced by Mode-S transponders with effect from 31 March 2005. Compliant transponders must support Surveillance Identifier codes. This capability is an essential prerequisite for the carriage and operation of Mode-S transponders in ECAC airspace. Surveillance Identifier codes have been standardised by ICAO, to provide additional selective interrogation capacity to that offered by the existing 16 (15 usable) Interrogator 10 [ Military Organisations Information Notice ]

Identifier codes. It has been recognised that the availability of Interrogator Identifier codes would be insufficient to serve the number of ground stations needed to be deployed in Europe. Thus the addition of 63 SI-codes will be essential for the provision of SSR Mode-S based surveillance services in the ICAO EUR Region. As appropriate, due account will be taken of the military requirement for Mode-S transponders to be selectable on/off from the cockpit or appropriate aircrew station accessible in flight. Where technically feasible, aircrew should be able to select the level of Mode-S being transmitted from their aircraft as demanded by the operational situation e.g. as follows: MAX Full functionality, MIN Basic Surveillance functionality, OFF Mode-S transponder disabled, Squitter Off Squitter disabled. Check your Airborne Equipment 1. Aircraft Identification input All aircraft, with Mode-S transponders installed must automatically report Aircraft Identification with effect from 31 March 2005. To meet the needs of the Air Traffic Services the Aircraft Identification transmitted is that employed in Item 7 of the ICAO flight plan. When no flight plan is available, the registration marking or tail number of the aircraft is to be employed (ICAO Annex 10, volume IV). The capability to downlink the Aircraft Identification parameter has to be embodied. It consists of a new piece of wiring and a possible change to the flight management system or alternatively, the addition or replacement of a suitable Control Panel Device. [ Military Organisations Information Notice ] 11

Military Organisation, what do you have to do? (cont d) 2. Antenna diversity Mode-S equipped aircraft with a maximum take-off mass in excess of 5700 kg or a maximum cruising true airspeed in excess of 463 km/h (250 kts) are to operate with antenna diversity, subject to airframe suitability. This is to ensure acceptable performance at all aircraft attitudes and interrogator illumination angles. 3. Assign ICAO 24-bit Addresses Sets of unique ICAO 24-bit aircraft addresses have been allocated to individual nations and NATO for military use. Sufficient aircraft addresses should be available to allow airframe identity concealment by randomly changing addresses. Procedures and protocols to prevent duplicate technical addresses being used simultaneously are recognised as a national and NATO responsibility. Aircraft addresses must be assigned by the responsible military authority and must be implemented in the aircraft. 4. Approve Aircraft for operational use Technical and operational approval of military aircraft will be required in accordance with national legislation, rules and regulations. Check your Sensor Equipment There is a military need for the acquisition and distribution of Mode-S data for the safe coordination and control of aircraft and, in an Air Defence context, to assist in the compilation of the Recognised Air Picture. 1. Military Sensors Data Acquisition Although Mode-S data can be retrieved from civil Mode-S interrogators, it is likely that a stand-alone Mode-S interrogator capability will be required in many platforms e.g. mobile ground-based radar, aircraft (NATO AWACS), ships and surface-to-air missile systems. Area multilateration systems (so-called passive systems ) might be considered as an alternative or complementary means of data acquisition. 12 [ Military Organisations Information Notice ]

2. Interrogator Code Allocation Due to the limited number of Interrogator Codes (Interrogator Identifier (II) and Surveillance Identifier (SI) codes), allocation will need to be closely co-ordinated and interrogation techniques adopted which are harmonised with peacetime civil ATS requirements and which will not undermine the integrity of the overall RF environment. NATO-AWACS aircraft The central allocation of Interrogator Codes is administered by EUROCONTROL on behalf of the ICAO European and North Atlantic Office. The process will be incorporated in the ICAO EUR-Region Air Navigation Plan and is overseen by a Civil/Military European Mode-S IC Allocation Co-ordination Group (MICoG). Alternatively, an interrogation capability based on the use of a generic IC code triggering a forced reply by the transponder could be considered if there is no need for continuous interrogation (if the use is supplemented with primary and secondary IFF/SIF information). 3. Use of the Mode-A Conspicuity Code In Mode-S airspace SSR Code A/1000 is reserved as a special purpose code denoting an aircraft conducting IFR flight as GAT, where the downlinked Aircraft Identification is validated as matching the Aircraft Identification entered in the flight plan. Correlation processes used in automated processing systems and currently dependant upon the use of discrete SSR Mode-A replies, might need to be adapted to maintain correlation between the flight plan and the aircraft radar return based on a match between the downlinked Mode-S Aircraft Identification and the Aircraft Identification in the flight plan. [ Military Organisations Information Notice ] 13

Flight Crew Awareness The goal of this section is to inform Flight Crews on Mode-S matters when flying IFR/GAT in an aircraft equipped for Mode-S Elementary or Enhanced Surveillance. Pre-flight Check that aircraft equipment meets the legal requirements. 1. Complete your Flight Plan When filling the flight plan, please follow ICAO rules as described in Appendix 2 of ICAO Document 4444. It is important that Item 7 is correctly filled. 2. Item 7: Aircraft Identification As per item 7 of the flight plan, flight crew are to set in the aircraft the Aircraft Identification, as follows: Either the correct ICAO aircraft operator's 3-letter designator and the flight number (e.g. AFP123, AME3576, AYB826, BAF151) Note The shortened format commonly used by Airlines (so called IATA code: AF123) is not compatible with the ground systems of the air traffic services Or the registration marking of the aircraft (e.g. EIAKO, 4XBCD, N2567GA) when this is the call sign used. 3. Item 10: Equipment Pilots will be required to enter one or more of the following letters into the flight plan to identify the serviceable surveillance equipment being carried. 14 [ Military Organisations Information Notice ]

N A C X P I S Nil Transponder - Mode-A (4 digits - 4096 codes) Transponder - Mode-A (4 digits - 4096 codes) and Mode-C Transponder - Mode-S without both Aircraft Identification and pressure-altitude trans mission Transponder - Mode-S, including pressure-altitude transmission, but no Aircraft Identification transmission Transponder - Mode-S, including Aircraft Identification transmission, but no pressure altitude transmission Transponder - Mode-S, including both pressure-altitude and Aircraft Identification transmission (Note: this is the new European Mode-S requirement) Pre-departure Flight crew will check if the aircraft is equipped for Elementary Surveillance and has a Mode-S transponder and interface for Aircraft Identification input. If the aircraft is equipped with Mode-S, the flight crew are to check that the Aircraft Identification as specified in Item 7 of the flight plan is correctly configured on the dedicated control box or on the FMS via for example the Control Display Unit. In-flight During daily operations, usually first identification of the aircraft will take place on start up or shortly after take-off. The pilot will still be requested to enter a Mode-A code at start up. If this Mode-A code is used in Mode-S airspace, it may not be discrete and will then be known as a conspicuity or non-unique code (SSR code 1000). Assuming that the point of departure is within Mode-S airspace, the Aircraft Identification (set in the aircraft as per Item 7 of the flight plan, or the aircraft registration marking if no flight plan has been filed) will be verified directly after takeoff by the first radar unit. It will be used as the means of identification for the remainder of the flight within Mode-S airspace. Once the aircraft leaves Mode-S airspace, the aircraft will be assigned a discrete Mode-3/A code. When a Mode-S equipped aircraft is inbound from non-mode-s airspace, it will, depending on the circumstances, retain its existing SSR code, be assigned another Mode-3/A code or be assigned SSR code 1000. [ Military Organisations Information Notice ] 15

Military Controller Awareness The goal of this Section is to brief Military Controllers (incl. ATC Controllers and Air Defence Controllers) on the upcoming Mode-S deployment in Europe. What will you see? 1. Radar Screen For many years controllers have been provided with identity (Mode-3/A) and altitude (Mode-C) information downlinked via the SSR transponder, supported by data processing and display functions. Current Elementary Enhanced SSR Mode 3/A, Mode C Aircraft ID Selected Altitude Radar Controller Working Position Radar If your unit is equipped with a Mode-S interrogator, the aircraft identification set in a Mode-S equipped aircraft will be automatically downlinked to your display along with the target response and altitude data. Direct recognition of the aircraft identification of a Mode-S equipped aircraft in a radar label provides verification of radar identification 4. 4- ICAO Doc 4444, 8.6.2.2.1d 16 [ Military Organisations Information Notice ]

If you share facilities with a civilian Air Control Centre, or your own unit is similarly equipped you may also benefit from additional downlinked data from a Mode-S Enhanced. Surveillance equipped aircraft as follows: Indicated Airspeed or Mach No Magnetic Heading Vertical rate of climb/descent Selected Altitude/Flight Level. What will you see if you are not Mode-S equipped? If your unit is not equipped with a Mode-S interrogator, Mode-S equipped aircraft will reply with Mode-3/A/C as before. However, in the case of overlapping cover with a civilian ATC Mode-S radar, you may see several targets squawking SSR code A1000. This will indicate flights operating as IFR/GAT where the downlinked aircraft identification has been matched with the aircraft identification entered in the flight plan, as explained in the previous Section. 2. Aircraft Identification The Aircraft Identification is inserted by the pilot through the appropriate control panel. With the Mode-S data link, the Aircraft Identification (e.g. AFP123, AME3576, AYB826, BAF151) as used in Item 7 of the ICAO flight plan is directly reported to the controller display. When no flight plan is filed, the aircraft registration is reported. It should be noted that the shortened format so called IATA code: AF2177 is not compatible with the ATC ground system. In case the pilot sets an erroneous Aircraft Identification, the air traffic controller will ask the pilot to re-enter it using the appropriate phraseology. [ Military Organisations Information Notice ] 17

Reference Material ICAO Documentation ICAO Regional Supplementary Procedures, DOC 7030/4 ICAO Annex 10 Volumes III and IV Amendment 77 ICAO Doc 9688 Manual on Mode-S Specific Services JTSO 2C112a, Minimum Operational Performance Specification for SSR Mode-S Transponders. (Adopts EUROCAE ED-73A). JAA Documentation JAA TGL n 13 updated to Rev. 1 to include Amendment 77 of ICAO Annex 10 SARPS. JAA NPA 20-12 of 1 August 2003 related to Enhanced Surveillance. EUROCONTROL EUROCONTROL Specimen AIC July 2000 Elementary Surveillance Transition Period- EUROCONTROL Specimen AIC April 2002 EUROCONTROL Permanent Commission Recommendation n 02/04 of 8th August 2002 Mode-S Enhanced Surveillance 3 States Project Master Plan Edition 1.0 of 30 August 2002. Common Framework for the Regulation of Mode-S Enhanced Surveillance. Volume 1 and 2 of the ATM Strategy for the years 2000+ States AICs Belgium AIC A15/2000 (includes Luxembourg) France AIC A02/01 Germany AIC 15/00 Switzerland AIC 26/00 The Netherlands AIC-B 10/03 United Kingdom AIC 88/2001 18 [ Military Organisations Information Notice ]

Mode-S Programme Contacts Colonel Luc VERVOORT, Head of the MILITARY Business Division Tel.: ++ 32 2 729 34 06 Fax: ++ 32 2 729 30 08. e-mail: luc.vervoort@eurocontrol.int Major Marc DE CAT, EUROCONTROL Military Expert, Tel.: ++ 32 2 729 34 05 Fax: ++ 32 2 729 30 08 e-mail: marc.de-cat@eurocontrol.int Pascal DIAS Mode-S Programme Manager EUROCONTROL Tel.: +32 2 729 3369 Fax.: +32 2 729 9086 e-mail: pascal.dias@eurocontrol.int Any Question? Should you have any further questions, please mail them to Modes@eurocontrol.int. Visit the Mode-S web site: http://www.eurocontrol.int/mode_s/ EATM (European Air Traffic Management) is a European-wide ATM enhancement programme managed by the EUROCONTROL Agency on behalf of EUROCONTROL Member States and other participating States. Its aim is to create a uniform EUROPEAN ATM environment, to ensure high levels of Safety and to enhance the Capacity as well as the overall performance of the European ATM system over time in the context of the EUROCONTROL ATM Strategy for the years 2000+ Mode-S - Enabler of the EUROCONTROL ATM 2000+ Strategy [ Military Organisations Information Notice ] 19

Published by: EUROCONTROL General Secretariat Directorate 96, rue de la Fusée B - 1130 Brussels Belgium Brochures available upon request from: EUROCONTROL Mode-S Programme Telephone: + 32 2 729 50 18 Fax: + 32 2 729 90 86 e-mail: leila.ikan@eurocontrol.int e-mail: marc.de-cat@eurocontrol.int