ENR 1.6  Radar Services And Procedures

Provision of Radar services within Lisboa AND SANTA MARIA FIR


Air Traffic Control Services within Lisboa and Santa Maria FIR radar coverage areas, with the exception of Aerodrome Control Service provided by TWRs, will normally be carried out with the use of radar.

Many factors, such as radar coverage, controller workload, equipment capabilities, traffic density and the atmospheric / meteorological conditions, may affect the performance of the Radar Services.

Radar services are provided within Lisboa and Santa Maria FIR in accordance with procedures specified in ICAO Doc 4444 - Chapter 8, supplemented by ICAO regional procedures contained in DOC 7030.

1.6.1   Supplementary Services

1.  The application of Radar Control Services

Radar control services provided by Air Traffic Control units are as follows:

  1. Radar separation of departing, arriving and en-route traffic;
  2. radar monitoring of air traffic to provide information on any significant deviation from normal flight path;
  3. radar vectoring when required; (see ENR 1.5.4. paragraph 2)
  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. assistance to aircraft experiencing difficulties in navigation or a failure of two-way communication;

1.6.2   Minimum Levels

Levels assigned by radar controller to pilots will provide a minimum terrain clearance according to the phase of flight.

1.6.3   Secondary Surveillance Radar (SSR) capabilities

The SSR equipment is:

  1. Capable of interrogating on Modes A and C;
  2. capable of decoding up to 4096 codes;

1.6.4   Position Reports   Lisboa FIR

Air Traffic Control units may instruct pilots to omit position-reports at compulsory reporting points or to report at specially designated reporting points, provided that the following conditions are fulfilled:

  1. The flight must have been identified and the Mode C read-out must have been checked;
  2. the flight must have received and acknowledge an ATC clearance;
  3. when it can be assumed that radar contact can be maintained;
  4. aircraft without Mode C automatic pressure altitude reporting capability must be in level flight.   Santa Maria FIR

See ENR 1.1.17

1.6.5   SSR Code Assignment

Aircraft about to enter Lisboa and Santa Maria FIR and having received code setting instructions from ATC, shall maintain that setting until otherwise instructed.

Aircraft shall acknowledge code setting instructions by read back.

Aircraft about to enter Lisboa and Santa Maria FIR and having not received code setting instructions shall:

  1. Maintain the code assigned to him when proceeding from an area of SSR coverage;
  2. setting the transponder on Mode A, Code 2000 if proceeding from an area without SSR coverage.

Aircraft immediately prior to the take-off run shall switch the transponder from "stand-by" to "on".

Aircraft immediately after landing shall switch-off the transponder.

Aircraft flying VFR outside controlled airspace and equipped with transponder, within SSR coverage, shall set the transponder on code 7000.

1.6.6   Radar and Radio Failure Procedures

1.  Radar Failure

In the event of radar failure or loss of radar identification, instructions will be issued to restore non-radar standard operation.

Reduced vertical separations of 500 FT or 1000 FT when below or above FL410, respectively, VMC clearances, and / or holding patterns may be prescribed as emergency measures.

2.  Radio Communication Failure

SSR equipped aircraft experiencing radio communication failures will operate the transponder on Mode A, Code 7600.

SSR may be used for acknowledging receipt of any instructions, to verify the aircraft receiver.

If the aircraft radio is completely unserviceable, the pilot should carry out the procedures of radio failure in accordance with Radio Communications Failure Procedure published in ENR 1.1.

The radar controller will provide separation to identified or non-identified aircraft experiencing complete communications failure, as far as possible, from other airspace users that constitute a hazard, until they have left the airspace concerned or have landed.

1.6.7   Emergency Procedures

SSR transponder failure and unlawful interference procedures.

1.  SSR transponder failure
1.1  Failure before intended departure

In case of a transponder which has failed and cannot be restored before departure, pilots shall:

  1. Inform ATS as soon as possible and preferably before submission of a Flight Plan;
  2. plan to proceed, as directly as possible, to the nearest suitable aerodrome where repair can be effected;
  3. insert in item 10 of the ICAO Flight Plan form under SSR the letter N of complete unserviceability of the transponder or in case of partial transponder failure, the character corresponding to the remaining transponder capability.
1.2  Failure during flight

In case of a transponder failure during flight within or bound to enter Lisboa and Santa Maria controlled airspace, pilots may expect that ATC units will endeavour to provide for continuation of flight to destination in accordance with the Flight Plan.

After landing, pilots shall make every effort to have the transponder restored to normal operation.
If repair cannot be achieved, pilots shall comply with the above provisions for failure before intended departure.

The exemption from the requirement for transponder equipment mentioned in and may be granted by the supervisor on duty in Lisboa ACC and Santa Maria OAC whenever conditions permit.

Change of ETD, cruising level and / or route of flight may become necessary.

2.  Unlawful interference procedures

Aircraft without prior instruction may set the transponder on Mode A, Code:

  • 7500 in case of unlawful interference;
  • 7600 in case of radio communications failure;
  • 7700 in case of emergencies.

1.6.8   Surveillance Separation   Santa Maria FIR (SSR/MLAT/ADS-B environment)


The minimum horizontal surveillance separation applicable within Santa Maria FIR between identified aircraft either with or without active VHF voice Direct Controller-Pilot communications is applied in accordance with ICAO Doc 4444 PANS ATM, paragraphs 8.7.3 and 8.7.4.

When conditions for application of horizontal surveillance separation are not met, other appropriate horizontal or vertical separation minima is applied, as published in AIP Portugal ENR 1.1.

The expected areas where each separation minima may be applied, with or without active VHF voice Direct Controller-Pilot communications is shown in ENR 1.6.12( Theoretical SSR/MLAT/ADS-B Surveillance Coverage Area - Santa Maria FIR).


Within the Santa Maria surveillance coverage area, when aircraft is identified and VHF voice DCPC is active, vectoring will be provided above applicable MSA.


ADS-B space based surveillance provided by Aireon has been implemented in Santa Maria FIR, alongside with and overlapping the existing ADS-B terrestrial antennas surveillance coverage. Distinct surveillance ATC procedures will be applied depending if VHF DCP communications exist or not.

Aircraft eligibility for ADS-B service in the Santa Maria FIR is based upon the compliance considerations of the:

  1. European Aviation Safety Agency (EASA) AMC 20-24; or
  2. FAA AC Nº 20-165A - Airworthiness Approval of ADS-B; or
  3. Configuration standards reflected in Appendix XI of Civil Aviation Order 20.18 of the Civil Aviation Safety Authority of Australia.

The aircraft and operator must be authorized by the State of the operator or State of Registry, as appropriate, therefore operators are required to obtain operational authorization prior to using ADS-B systems within the Santa Maria FIR. There are no restrictions for accommodating aircraft that are not eligible for ADS-B ATS services.

The appropriate standard separation minimum will be applied between these aircraft and other aircraft. It is responsibility of the crew to ensure that the accuracy and integrity of the data transmitted from the ADS-B system is sufficient. The following rules applies:

An aircraft carrying 1090 MHz extended squitter (1090ES) ADS-B equipment shall disable ADS-B transmission unless:

  1. the aircraft emits position information of an accuracy and integrity consistent with the transmitted values of the position quality indicator; or
  2. the aircraft always transmits a value of 0 (zero) for one or more of the position quality indicators (NUCp, NIC, NAC or SIL), when the requirements of a) above cannot be met; or
  3. the operator has received an exemption granted by NAV Portugal.

Aircraft operators wishing to receive an exemption from the procedures specified in c. above for an individual flight shall apply for an exemption to NAV Portugal at least 5 days in advance of the flight. Any approvals for such exemptions may be contingent on specific conditions such as routing, flight level and time of day.

Applications for exemptions shall be sent to NAV Portugal at e-mail address: Email: smaoacc@nav.pt

GNSS provides the positioning information for ADS-B, so when the GNSS receiver is turned off, the aircraft will become invisible to ADS-B surveillance.

ADS-B transmitters must not send spurious information. If ATC instructs the crew to stop transmitting, they must turn off the ADS-B transmitter. Many ADS-B installations share controls with the SSR transponder, making it impossible to operate the two systems independently. If unable to comply with a particular instruction, the crew must advise ATC and ask for alternative instructions.

ATC is not allowed to use downlinked ADS-B data for determining aircraft position unless the position quality indicators (NUCp, NIC, NAC or SIL) included in the ADS-B message are of a certain value. If the position quality indicators are of a lower value the aircraft will not be presented to the controller as an ADS-B based surveillance target and will not receive ADS-B services.

The aircraft identification set via the cockpit interface must be IDENTICAL to the aircraft identification filled in ICAO FPL Item 7.The callsign enables the air traffic control system to correlate the ADS-B track with the flight plan data.

If the crew enters the callsign incorrectly, ATC might not be able to see the aircraft, or might confuse it with another. The callsign is flight critical information, therefore should be carefully managed by the crew.

If the callsign has been entered incorrectly, ATC will instruct the crew to re-enter ADS-B aircraft identification.

  • If the crew is able to, they must then re-set the callsign to exactly match the callsign in ICAO FPL Item 7.
  • If they are unable to re-set the callsign in flight then advice ATC of the inability to comply.

Incorrect callsign entry by an air transport operator is a reportable event - ATC must raise a safety incident report.

See ENR 1.1.17 for voice position reports requirements in Santa Maria FIR.

Standard ICAO phraseology will be applied. The crew may not always know which surveillance system is being used and how they are being controlled. Within the VHF coverage area, the crew may be told only that they have been “identified”, but it may not be clear whether they have been identified with radar/MLAT, ADS-B or both. Unless ATC uses specific phraseology, use both ADS-B and transponder equipment to give the controller the best surveillance picture.

If ADS-B equipment B1 or B2 has been filed in Item 10b of the ICAO FPL and ADS-B Space based surveillance services are available, the pilot shall consider that the aircraft is identified when the aircraft is operating above FL285. The controller will not inform the pilot of the identification. The controller will inform the pilot if the aircraft is not identified.

CPDLC provides communication beyond VHF coverage, allowing the application of reduced separations for aircraft under ADS-B Space Based surveillance and controllers will in many cases use CPDLC for communication even though a listening watch on the assigned VHF frequency is maintained. ADS-C enables ATC to perform route conformance monitoring for downstream waypoints.

When equipped with FANS CPDLC and/or ADS-C, the crew should ensure that their system is logged on to LPPO when operating within the Santa Maria FIR OCA. This applies even when the aircraft is provided with Radar, MLAT and/or ADS-B (terrestrial or space based) surveillance services.

Some aircraft equipped with first generation ADS-B avionics (DO-260 compliant transponders) only have the capability to transmit an ADS-B general emergency alert, regardless of the code (7500, 7600, 7700) selected by the pilot. As a result the controller will not be aware of the nature of the emergency if the aircraft is operating outside radar coverage. When the aircraft has this limitation the crew must use other means to inform the controller about the nature of the emergency.

1.6.9   Secondary Radar (SSR) Stations

1.6.10   Radar Vectoring Chart - Lisboa

1.6.11   Theoretical Secondary Radar Coverage - Lisboa FIR

1.6.12   Theoretical SSR/MLAT/ADS-B Surveillance Coverage Area- Santa Maria FIR

Figure 1.  Theoretical SSR/ MLAT/ ADS-B (terrestrial) Surveillance Coverage Area
Figure 2.  Additional ADS-B (space based) Surveillance Coverage Area