ENR 1.6  ATS surveilLance services and procedures

Applicable ICAO Documents:

1   Primary radar

1.1   Supplementary services
1.1.1  A radar unit normally operates as an integral part of the parent ATS unit and provides radar service to aircraft, to the maximum extent practicable, to meet the operational requirement. Many factors, such as radar coverage, controller workload and equipment capabilities, may affect these services, and the radar controller shall determine the practicability of providing or continuing to provide radar services in any specific case.
1.1.2  A pilot will know when radar services are being provided because the radar controller will use the following call signs:
  1. aircraft under area control - "LJUBLJANA RADAR"
  2. aircraft under approach control - "LJUBLJANA RADAR"
1.1.3  Ljubljana area control and Ljubljana approach control service use surveillance data from five radar stations and one WAM system:
  1. OLS - station at Oljska gora, (460545N 0143401E), range PSR 80 NM, range SSR 160 NM;
  2. KOR - station at Koralpe mountain, Republic of Austria, (464714N 0145816E), range SSR 150 NM
  3. VRH - station at Ljubljanski vrh hill (455551N 0141753E) range SSR 200 NM
  4. CHR - station at Airport Ljubljana, (461305N 0142830E), range PSR 60 NM, range SSR 200 NM
  5. RON - station at Trieste Airport, Italy, (454950N 0132910E) range PSR 60 NM, range SSR 189 NM
  6. WAM - system covering Slovenia FIR + 30 NM beyond its boundaries
1.2   The application of radar control service
1.2.1  Radar identification is achieved according to the provisions specified by ICAO.
1.2.2  Radar control service is provided in controlled airspace to aircraft operating within the MURA TMA, DOLSKO 1 TMA, DOLSKO 2 TMA, LJUBLJANA 1 TMA, LJUBLJANA 2 TMA, LJUBLJANA 3 TMA, LJUBLJANA 4 TMA and UPPER CTA LJUBLJANA. Radar control service in MARIBOR 1 TMA, MARIBOR 2 TMA and PORTOROZ TMA is not provided.
This services may include:
  1. radar separation of arriving, departing and en-route traffic
  2. radar monitoring of arriving, departing and en-route traffic to provide information on any significant deviation from the normal flight path
  3. radar vectoring when required
  4. assistance to aircraft in emergency
  5. assistance to aircraft crossing controlled airspace
  6. warnings and position information on other aircraft considered to constitute a hazard
  7. information to assist in the navigation of aircraft
1.2.3  The minimum horizontal radar separation within LJUBLJANA FIR is 3 NM at FL 195 or below and 5 NM above FL 195.
1.2.4  Levels assigned by the radar controller to pilots will provide a minimum terrain clearance according to the phase of flight.
1.2.5  Final radar approaches.
  1. Surveillance radar approach - SRA is not applicable
  2. Precision radar approach - PAR is not applicable
1.2.6  Ljubljana Flight Information Service - "LJUBLJANA INFORMATION" may use surveillance derived information in the provision for flight information service in class E and G airspace. Surveillance information serves only as an aid to provide pilots with more accurate flight information.
The reception of flight information service does not relieve the pilot-in- command of an aircraft of any responsibilities and the pilot-in-command shall make the final decision regarding any suggested alteration of flight plan (SERA.9001(b)).
1.3   Radar and air-ground communication failure procedures
1.3.1   Complete radar failure  In the event of complete radar failure except for air-ground communications, with aim to clear and close the airspace, instructions will be issued to restore non standard separation on the frequency of the ATC unit concerned.
Note: As an emergency measure, use of flight levels separated by 500 ft below FL 410 or 1000  ft at or above FL 410 may be resorted if standard radar separation cannot be provided.
at or above 1000 FT
--------FL 410--------
below 500 FT  The radar controller will inform pilots about the termination of radar service. Exception are occasions when assurance that the radar failure will be of a very limited duration exists.
1.3.2   Air-ground voice communication failure  The radar controller will establish whether the aircraft radio receiver is working by instructing the pilot to carry out a turn or turns. If the turns are observed, the radar controller will continue to provide radar service to the aircraft.  If the aircraft's radio is completely unserviceable, the pilot should carry out the procedures for radio failure in accordance with ICAO provisions (see paragraph ENR 1.8.5. If radar identification has already been established, the radar controller will vector other identified aircraft clear of its track until such time as the aircraft leaves radar cover.
1.4   Graphic portrayal of area of radar coverage
1.4.1  The area of radar coverage is identical to that of SSR. Radar coverage includes minimum airway altitudes in the whole LJUBLJANA FIR, except in TMA PORTOROZ.

2   Secondary surveillance radar (SSR)

2.1   General
  1. When an aircraft carries a serviceable SSR transponder, the pilot shall operate the transponder at all times during flight, regardless of whether the aircraft is within or outside airspace where SSR is used for ATS purposes (SERA.13001(a)).
  2. Pilots shall not operate the IDENT feature unless requested by ATS (SERA.13001(b)).
  3. Except for flight in transponder mandatory zones (TMZs), aircraft without sufficient electrical power supply are exempted from the requirement to operate the transponder at all times (SERA.13001(c)).
  4. The carriage and operation of SSR transponder is compulsory for all aircraft operating in class C and D airspace and within transponder mandatory zones (TMZs):
  • bellow FL245 with capability of replying to Mode A/C or Mode S ELS and
  • above FL245 with capability of replying to Mode S ELS,
as defined in ENR 2.2.1 within LJUBLJANA FIR.
Alternate provisions from the requirement to carry a transponder mode A/C or S in class C or D airspace or within transponder mandatory zones (TMZs) is hereby granted to the aircraft operators for VFR flights operating:
  • from private airfields located within LJUBLJANA CTR and flying in TMZ LJLJ in compliance with provisions of bilateral agreement between particular private airfield operator and Slovenia Control, Ltd.,
An alternative provision to comply with the transponder usage in the class C and D airspace and within transponder mandatory zones (TMZs) requirement may be granted for particular flights, provided that the request is made prior or during flight by radio or telephone to responsible ATS unit.
The carriage of the serviceable transponder capable replying to Mode A and C or Mode S does not apply to unmanned aircraft systems with a take off operating mass of less than 150 kg from the surface of the earth to a height of 164 ft above the ground.
Operators of non-equipped State aircraft (communicated as per Article 8(3) of SPI Regulation) and operators of aircraft not equipped (in accordance with Article 5(5) of the SPI Regulation), operating within the Single European Sky airspace, shall include the indicators SUR/EUADSBX or SUR/EUEHSX or SUR/EUELSX or a combination thereof, in Item 18 of the flight plan.
Non Mode-S/ADS-B equipped State aircraft will be considered only if the aircraft is equipped with Mode A and Mode C SSR transponder.To this aircraft discrete SSR code will be assigned by ATS unit.
2.2   Emergency procedures
  1. To indicate that it is in a specific contingency situation, the pilot of an aircraft equipped with SSR shall (SERA.13005(a)):
    1. select Code 7700 to indicate a state of emergency unless ATC has previously directed the pilot to operate the transponder on a specified code. In the latter case, a pilot may nevertheless select Code 7700 whenever there is a specific reason to believe that this would be the best course of action;
    2. select Code 7600 to indicate a state of radio-communication failure;
    3. attempt to select Code 7500 to indicate a state of unlawful interference. If circumstances so warrant, Code 7700 should be used instead.
  2. Except in the cases described in (a) above, the pilot shall SERA.13005(b)):
    1. select codes as instructed by the ATS unit; or
    2. in the absence of ATS instructions related to code setting, select code 2000 or another code as prescribed by the competent authority; or
    3. when not receiving air traffic services, select code 7000 in order to improve the detection of suitably equipped aircraft unless otherwise prescribed by the competent authority.
  3. When it is observed that the code shown on the situation display is different from what has been assigned to the aircraft (SERA.13005(c)):
    1. the pilot shall be requested to confirm the code selected and, if the situation warrants, to reselect the correct code; and
    2. if the discrepancy between assigned and displayed codes still persists, the pilot may be requested to stop the operation of the aircraft's transponder. The next control position and any other affected unit using SSR and/or multilateration (MLAT) in the provision of ATS shall be informed accordingly.
Note: Continuous monitoring of responses on Mode A/3, Code 7700 is provided.
2.3   Air-ground communication failure and unlawful interference procedures
2.3.1   Air-ground communication failure procedure
In the event of an aircraft radio communication failure, a pilot shall select Mode A/3, Code 7600 and follow established procedures; subsequent control the aircraft will be based on those procedures.
2.3.2   Unlawful interference procedure
(aa) An aircraft which is being subjected to unlawful interference shall endeavour to set the transponder to Code 7500 and notify the appropriate ATS unit of any significant circumstances associated therewith and any deviation from the current flight plan necessitated by the circumstances, in order to enable the ATS unit to give priority to the aircraft and to minimise conflict with other aircraft.
(ab) If an aircraft is subjected to unlawful interference, the pilot-in-command shall attempt to land as soon as practicable at the nearest suitable aerodrome or at a dedicated aerodrome assigned by the competent authority, unless considerations aboard the aircraft dictate otherwise.
2.4   SSR codes for special purposes
2.4.1   The following codes shall be used by pilot (SERA.13005):
  • (2) in the absence of ATS instructions related to code setting, select code 2000 or another code as prescribed by the competent authority; or
  • (3) when not receiving air traffic services, select code 7000 in order to improve the detection of suitably equipped aircraft unless otherwise prescribed by the competent authority.
2.5   ACAS Procedures
2.5.1  Responsibility during Airborne Collision Avoidance System (ACAS) operation within the airspace of LJUBLJANA FIR (SERA.11014):
  1. ACAS II shall be used during flight, except as provided in the minimum equipment list specified in Commission Regulation (EU) No 965/2012 (1) in a mode that enables RA indications to be produced for the flight crew when undue proximity to another aircraft is detected. This shall not apply if inhibition of RA indication mode (using traffic advisory (TA) indication only or equivalent) is called for by an abnormal procedure or due to performance-limiting conditions.
  2. In the event of an ACAS RA, pilots shall:
    1. respond immediately by following the RA, as indicated, unless doing so would jeopardise the safety of the aircraft;
    2. follow the RA even if there is a conflict between the RA and an ATC instruction to manoeuvre;
    3. not manoeuvre in the opposite sense to an RA;
    4. as soon as possible, as permitted by flight crew workload, notify the appropriate ATC unit of any RA which requires a deviation from the current ATC instruction or clearance;
    5. promptly comply with any modified RAs;
    6. limit the alterations of the flight path to the minimum extent necessary to comply with the RAs;
    7. promptly return to the terms of the ATC instruction or clearance when the conflict is resolved; and
    8. notify ATC when returning to the current clearance.
2.6   System of SSR Code assignment
Codes are assigned according to ORCAM.
2.7   Graphic portrayal of area of SSR coverage
See Chart "Minimum Flight Altitudes when using En-route Surveillance Radar"

3   Automatic dependent surveillance - broadcast (ADS-B)

In LJUBLJANA FIR Automatic dependent surveillance - broadcast (ADS-B) is not yet implemented.

4   Other relevant information and procedures

No information available.