ENR 1.6  Radar services and procedures

1.6.1  PRIMARY RADAR

1.6.1.1  Radar Units

Radar units in the BAHRAIN FIR / BAHRAIN UIR operate as integral parts of the parent ATS unit and provide radar service, to the maximum extend practicable, to meet the operational requirement. Factors, such as radar coverage, controller workload, and equipment capabilities, may affect these services, and the radar controller shall determine whether he is able to provide, or continue to provide, radar services in any specific case.

1.6.1.2  Radar Service

A pilot will know when radar services are being provided because the radar controller will use the ATS callsign depending on the position of the aircraft in BAHRAIN FIR / BAHRAIN UIR and under what ATS unit the aircraft is operating, followed by "Radar" for example:

  1. Aircraft under Area Control - "BAHRAIN RADAR";

  2. Aircraft under Approach Control - "BAHRAIN APPROACH".

1.6.1.3  RADAR COVERAGE

The following radar units operate within the BAHRAIN FIR / BAHRAIN UIR:

  1. BAHRAIN MSSR:

    Position: 261637.66 N 0503751.96 E

    Range: 230 NM

  2. BAHRAIN TAR with co - located MSSR:

    Position: 261600.45 N 0503845.69 E

    Range: Primary 80 NM, Secondary 230 NM

(Note that Bahrain may delegate the resonsibility for providing ATS, FIS and Alerting Service to other radars when aircraft are within their cover in the BAHRAIN FIR / BAHRAIN UIR.)

1.6.1.4  THE APPLICATION OF RADAR CONTROL SERVICE
1.6.1.4.1 RADAR IDENTIFICATION is achieved according to the provisions specified by ICAO.
1.6.1.4.2 RADAR SERVICES

Radar control service is provided in controlled airspace to aircraft operating within BAHRAIN CTA and on airways within Bahrain radar coverage. These 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 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;

  8. information on observed weather.

Radar Advisory Service and Flight Information Service are provided to identified aircraft operating within the BAHRAIN FIR / BAHRAIN UIR to the extent possible within radar cover.

1.6.1.4.3 MINIMUM HORIZONTAL RADAR SEPARATION

BAHRAIN PSR (TAR Range 80): 20 NM when one aircraft is supersonic, otherwise 5 NM.

BAHRAIN MSSR: 20 NM when one aircraft is supersonic, otherwise 10 NM reducing to 5 NM within 150 NM of radar head.

TERRAIN CLEARANCE

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

1.6.1.5  RADAR AND RADIO FAILURE PROCEDURES
1.6.1.5.1  Radar failure

In the event of radar failure or loss of radar identification, instructions will be issued to restore non - radar standard separation and the pilot will be instructed to communicate with the parent ATS unit.

1.6.1.5.2 Radio failure
1.6.1.5.2.1 The radar controller will establish whether the aircraft radio receiver is working by instructing the pilot to operate the SSR transponder (see also GEN 1.5) or, if the aircraft is not SSR equipped, to carry out a turn. If appropriate actions are observed the radar controller will continue to provide radar services to the aircraft.
1.6.1.5.2.2 Aircraft unable to receive radio transmissions shall comply with the ICAO radio communication failure procedures as detailed in Annex 2 para 3.6.5. If radar identification was established prior to radio failure the radar controller will vector other identified aircraft clear of the radio failure aircraft until such time as the aircraft leaves radar coverage or has landed.
1.6.1.5.2.3 Flights departing from BAHRAIN INTERNATIONAL airport on a radar clearance and experiencing a total radio communication failure shall carry out the following procedures:

IN VMC:

Continue to fly in VMC and land at the nearest suitable aerodrome.

In IMC:

Maintain last assigned heading and flight level or altitude for a period of three minutes after departure or to a distance of 12 DME BAH whichever occurs earlier. Thereafter continue according to current flight plan by routing direct to the first en - route reporting point and climbing to the last acknowledged en -route flight level cleared by ATC.

1.6.1.6  AIRBORNE COLLISION AVOIDANCE SYSTEM (ACAS)

All aircraft fitted with ACAS II equipment, shall be fitted with software version 7.1 with mode S transponder compliant with Annex 10, Volume IV within the OBBB EFF 1st Jan 2017.

REF. ICAO DOC 8168 - OPS / 611 VOL. I PART VIII CHAPTER 3

1.6.1.6.1 The information provided by ACAS is intended to assist pilots in the safe operation of aircraft. The traffic alert and collision avoidance system - TCAS II is accepted as a suitable system provided the installation is certified for use by the State of Registry of the aircraft concerned and it’s operation is in accordance with instructions for use of the equipment laid down in the company operations manual issued by the aircraft operator.
1.6.1.6.2 Nothing in the following procedures shall prevent pilots - in - command from exercising their best judgement and full authority in the choice of the best course of action to resolve a traffic conflict.
1.6.1.7  USE OF ACAS INDICATIONS

ACAS indications are intended to assist pilots in the active search for, and visual acquisition of, the conflicting traffic and the avoidance of potential collisions. The following safety considerations apply:

  1. Pilots shall not manoeuvre their aircraft in response to traffic advisories only;

    Note: Traffic advisories are intended to assist in visual acquisition of conflicting traffic and to alert the pilot to the possibility of a resolution advisory. The restriction in the use of traffic advisories is due to the limited bearing accuracy and to the difficulty in interpreting altitude rate from displayed traffic information.

  2. In the event of a resolution advisory, ATC will expect the pilot to respond. If avoiding action is necessary, alteration of flight path should be limited to the minimum extent necessary to comply with the resolution advisories;

  3. Pilots who deviate from an air traffic control clearance in response to a resolution advisory shall promptly return to the terms of the previous air traffic control instruction or clearance when the conflict is resolved and shall notify the appropriate ATC unit as soon as possible.

Figure 7. AREA OF RADAR COVERAGE
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1.6.2  SECONDARY SURVEILLANCE RADAR (SSR)

1.6.2.1  Emergency Procedures
1.6.2.1.1 Except as provided for paragraph ENR 1.6.2.2 below, pilot shall operate transponders and select modes and codes in accordance with ATC instructions. In particular, when entering BAHRAIN FIR / BAHRAIN UIR pilots who have already received specific instructions from ATC concerning the setting of the transponder shall maintain that setting until otherwise instructed.
1.6.2.1.2 Pilots of aircraft about to enter the BAHRAIN FIR / BAHRAIN UIR who have not received specific instructions from ATC concerning the setting of the transponder shall operate the transponder on Mode A / 3 Code 2000 before entry and maintain that setting until otherwise instructed.

Mode C, if fitted, is to be selected at all times.

1.6.2.1.3 If the pilot of an aircraft encountering a state of emergency has previously been instructed by ATC to operate the transponder on a specific code, this code setting shall be maintained until otherwise advised. In all other circumstances, the transponder shall be set to Mode A / 3 Code 7700.
1.6.2.1.4 Notwithstanding the procedures set out above, a pilot may select Mode A / 3 Code 7700 wheneever the nature of the emergency is such that this appears to him to be the most suitable course of action.

Note: Continuous monitoring of responses on Mode A / 3 Code 7700 is provided.

1.6.2.2  Radio communication failure and unlawful interference procedures
1.6.2.2.1 Radio Communication failure procedures

In the event of an aircraft radio receiver failure, a pilot shall select Mode A / 3 Code 7600 and follow established procedures, and subsequent control of aircraft will be based on these procedures.

1.6.2.2.2 Unlawful Interferernce procedure

Pilots of aircraft in flight subjected to unlawful interference shall endeavour to set the transponder to Mode A Code 7500 to give indication of the situation, unless circumstances warrant the use of A / 3 Code 7700.

Note: Continuous monitoring in responses on Mode A / 3 Code 7500 is provided.

1.6.2.3  System of SSR Code assignment

Codes are assigned according to the ICAO "ORIGINATING REGION CODE ALLOCATION METHOD2 - ORCAM - for the MID / ASIA Region.

1.6.2.4  Mode S operation within OBBB FIR
1.6.2.4.1  INTRODUCTION

The provision of air traffic services (ATS) using SSR Mode S in Bahrain FIR airspace will rely on a unique ICAO 24-bit aircraft address for selective interrogation of individual aircraft. The 24-bit aircraft address is also an essential element of the airborne collision avoidance system (ACAS II). In addition, Mode S surveillance requires the reporting of aircraft identification as stated below.

Pilots of aircraft equipped with mode ’S’ transponder having an aircraft identification feature shall set the aircraft identification in the transponder while operating within OBBB FIR. This setting shall correspond to the aircraft identification specified in item 7 of the standard ICAO FPL, or if no FPL has been filed, the aircraft registration. ATC equipment requires strict compliance with mode ’S’ settings to ensure proper radar tracking. Inability to comply with these requirements may result in aircraft being denied entry into OBBB class ’A’ airspace.

The aircraft address shall be one of 16 777 214 twenty-four-bit aircraft addresses allocated by ICAO to the State of Registery or common mark registering authority and assigned as prescribed in the ICAO Annex 10.

All Mode S equipped aircraft engaged in international civil aviation are required to have an aircraft identification feature as prescribed in ICAO Annex 10.

This guidance is provided to ensure consistency regarding 24-bit aircraft addresses and the reporting of aircraft identification relevant to the operational introduction of Mode S Elementary and Enhanced Surveillance. In particular:

  1. Adherence to the world-wide scheme for assignment of ICAO 24-bit Aircraft Addresses.

  2. Correct setting of Aircraft Identification by flight crew.

1.6.2.4.2   THE ICAO 24-BIT AIRCRAFT ADDRESS

Instances occur of incorrect 24-bit aircraft addresses being installed/hard-wired on individual aircraft. This has happened not only on first installation of Mode S transponder but also when a major modification has been made to the Mode S equipment, and following a change of State of Registration. Incorrect installation, such as setting the address to all zeros, or, inadvertent duplication of an address can pose a severe risk to flight safety. In particular, the airborne collision avoidance system (ACAS II), performs on the assumption that only a single, unique 24-bit aircraft address per airframe exists. The performance of ACAS II can be seriously degraded and in some instances disabled if an incorrect or duplicate address is installed on an aircraft. Incorrect or duplicated 24-bit aircraft addresses will also undermine the effectiveness of surveillance services based on SSR Mode S.

It is essential that aircraft operators comply with the aircraft address assignment procedures of the state regulatory authority to which blocks of addresses have been allocated by ICAO.

Note: Telephony designators for aircraft operating agencies are contained in ICAO Doc 8585.

The world-wide addressing scheme has been designed so that, at any one time, no address is assigned to more than one aircraft. Only one address can be assigned to an aircraft and it can not be changed except under exceptional circumstances authorised by the State Regulatory Authority concerned.

When an aircraft changes it’s State of Regulatory of Registry, the previously assigned address is to be relinquished and a new address assigned by the new registering authority.

It is essential that the aircraft address is periodically verified using ramp tests. Such checks must also be conducted when a major maintenance check has taken place and when the aircraft has changed registration, to ensure that a newly assigned address has been properly set.

1.6.2.4.3   CORRECT SETTING OF AIRCRAFT IDENTIFICATION

To comply with airborne equipment requirements, Mode S transponder equipped aircraft must incorporate an Aircraft Identification Feature. Correct setting of aircraft identification is essential for the correlation of radar tracks with flight plan data in the ATM and Airport Operator ground systems. Initial operational trials using SSR Mode S have shown that many aircraft are transmitting incorrect aircraft identification, e.g. J9165 instead of JZR165. Such erroneous settings of aircraft identification prohibit automatic flight plan correlation and, if perpetuated, will severely limit the effectiveness of Mode S to relieve the shortage of SSR codes.

In accordance with ICAO Doc 8168 [PANS-OPS] Vol. I, Part III, flight crew of aircraft equipped with Mode S having an aircraft identification feature shall set the aircraft identification in the transponder. The setting shall correspond to the aircraft identification specified in item 7 of the ICAO flight plan, or, if no flight plan has been filed, the aircraft registration.

Note: All Mode S equipped aircraft engaged in international civil aviation are required to have an aircraft identification feature.

Note: No zeroes, dashes or spaces are to be added when the aircraft identification consists of less than 7 characters.

Mode (S) and Selected Altitude use in the OBBB FIR

The provision of the selected altitude set by aircrew, to the controller, gives them the ability to intervene, where the selected altitude does not match the clearance. This greatly reduces the chance of a Level Bust.

Selected altitude data is presented as either a flight level or an altitude, depending on surveillance system settings, For ATC and Air-Ground Communication purposes, the generic phrase ’Seleted level’ is often used to encompass data presented as either an altitude or flight level.

The following factors are preventable, using the display of a Selected Altitude / CFL mismatch:

- Correct pilot Read-back or Hear-back followed by incorrect action;

- Incorrect pilot read-back by correct aircraft;

- Pilot read-back by incorrect aircraft.

The ATM System will generate an alert where there is a discrepancy between the Cleared Level and the aircraft Selected Altitude; Controllers are required to advise the pilot using the following phrase; "(Callsign), Check Selected Level. Cleared Level is (correct cleared level)"

Pilots of Mode (S) equipped aircraft, operating within the OBBB FIR shall ensure that their current cleared level is set as the selected altitude in the aircraft mode control panel, unless established on final approach for OBBI.

Any failure to comply with the above, pilots shall immediately inform ATC.

1.6.2.4.4   FURTHER INFORMATION

Or guidance may be obtained from:

Bahrain Senior Air Traffic Control Officer

+973 17 32 9927

satco@mtt.gov.bh

Figure 8. GRAPHIC PORTRAYAL OF AREA OF COVERAGE OF RADAR-SSR
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