3 SECONDARY SURVEILLANCE RADAR (SSR)

3.1 SSR Sites
- 3.1.1 SSRs, with a maximum range of 256 NM, are located at the following sites:
  - (a) Ruaotuwhenua 12.5 NM north-west of Auckland Airport;
  - (b) Te Weraiti Kaimai Range 6.5 NM east of Matamata Township;
  - (c) Ballance Tararua Range between Palmerston North aerodrome and Pahiatua Township;
  - (d) Hawkins Hill 3.5 NM west of Wellington Airport;
  - (e) Mt Robertson 3 NM south-east of Picton Township;
  - (f) Cass Peak Port Hills 9.5 NM south-east of Christchurch Airport.
- 3.1.2 The SSR sites are all elevated to improve low level cover. They are shown on the appropriate topographical charts.
3.2 Transponders
- 3.2.1 Transponders allow positive aircraft identification and altitude information to be displayed to air traffic control. This enables controllers to quickly determine where potential conflicts could occur.
- 3.2.2 In addition, operation of transponders at all times increases safety when operating in the vicinity of ACAS equipped aircraft, and will enhance Search and Rescue and emergency action when operating within surveillance cover.
- 3.2.3 Adherence to transponder operating procedures provides both VFR and IFR aircraft with a higher degree of safety and reduces communications, giving a more efficient service.
- 3.2.4 An aircraft equipped with Mode S which has an aircraft identification capability must transmit the aircraft identification as specified in Item 7 of the ICAO flight plan or, when no flight plan has been filed, the aircraft registration.
- 3.2.5 Aircraft equipped with Mode S must include the Mode S address in Item 18 of the flight plan, e.g. CODE/C81111.
- 3.2.6 ATC must verify with the pilot at least once during the flight that the altitude information received from the transponder is correct, prior to using that information for separation purposes.
- 3.2.7 ATC will receive an alert where the selected level entered into the mode control panel/flight control unit of an enhanced surveillance (EHS) Mode-S equipped aircraft does not match the cleared level issued by the controller or intermediate level contained in the SRC. ATC will advise the aircraft of the discrepancy, e.g. "FASTAIR 927 CHECK SELECTED LEVEL. CLEARED LEVEL IS 10,000 FT"

3.3.1 SSR codes are allocated by radar equipped ATS facilities to controlled flights operating within their area of responsibility, and to controlled flights entering the New Zealand FIR from the Auckland Oceanic FIR.
3.3.2 Codes for use in New Zealand are allocated in accordance with international agreements and instructions contained in the Manual of Air Traffic Services.
3.3.3 The pilot operating an aircraft, not in a formation, in transponder- mandatory airspace must set the transponder:
- (a) to the appropriate code assigned by ATC for the flight; or
- (b) if not assigned a code by ATC, in accordance with Table ENR 1.6-1; or
- (c) if an in-flight emergency, loss of communications, or an unlawful interference occurs, in accordance with Table ENR 1.6-2.

Table ENR 1.6-1
Transponder Code Allocation
Flight Rules	Type of Aircraft	SSR Code
IFR including Flight Rules Y and Z	Within Auckland Oceanic FIR: Inbound to or overflying New Zealand FIR Departing New Zealand FIR	Code assigned on departure Last code assigned, or 2000
IFR including Flight Rules Y and Z	Within New Zealand FIR	Code assigned, or 2000
VFR	Fire suppression and reconnaissance (fixed wing and helicopters)	0111
	Civil aeroplanes other than gliders	1200
	Gliders and balloons	1300
	Aircraft in General Aviation Areas	1400
	Civil helicopters	1500
	Within Auckland Oceanic FIR	2000
	Aircraft operating in aerodrome traffic circuit at controlled aerodromes	2200
	Defence aeroplanes	6000
	Defence helicopters	6500

Table ENR 1.6-2
Emergency SSR Codes
Occurrence	SSR Code
Unlawful interference	7500
Loss of radio communication	7600
In-flight emergency when no code has been allocated by ATC	7700

3.3.4 In military formations, an individual SSR code will be assigned to each aircraft in the formation. The last number of the code should correspond to the aircraft's formation number e.g. RED 1 = 6121, RED 2 = 6122, etc.
3.3.5 In civil formations, an SSR code will be assigned to the formation leader, and all other aircraft will be assigned code 2020.
3.3.6 Unless otherwise instructed by ATC, all aircraft in the formation are to squawk NORMAL, except that within airspace under the control of Ohakea, the leader is to squawk NORMAL and all other aircraft are to squawk STANDBY, unless otherwise instructed.
3.3.7 Where members of a formation have been instructed by ATC to squawk STANDBY the formation leader must advise ATC immediately there is a relaxation or significant change (laterally or vertically) to the formation's configuration. This is to enable ATC to re-evaluate separation requirements between the aircraft in the formation and other aircraft.

3.4 Transponder Procedures for Pilots
- 3.4.1 The use of SSR transponder and altitude reporting equipment is prescribed in CAR 91.247.
- 3.4.2 Pilots must operate transponders in accordance with ATC instructions and must acknowledge by reading back code setting instructions.
- 3.4.3 Pilots must not operate the "IDENT" feature unless instructed by ATC.
- 3.4.4 Within the Auckland Oceanic FIR (west of 180°) and the New Zealand FIR, an aircraft carrying 1090 MHz extended squitter (1090ES) ADS-B equipment shall disable ADS-B transmission unless:
  - (a) the aircraft emits position information of an accuracy and integrity consistent with the transmitted value of the position quality indicator; or
  - (b) the aircraft always transmits a value of 0 (zero) for one or more of the position quality indicators (NUCp, NIC, NAC or SIL); or
  - (c) the operator has received specific dispensation from the Director of Civil Aviation.
  - 3.4.5 The pilot of an aircraft who has received specific instructions concerning the transponder setting, or who is operating a VFR code in transponder mandatory airspace, must, unless complying with emergency procedures, maintain that setting until otherwise advised by an ATS unit.
  - 3.4.6 All aircraft on an IFR flight plan will receive a specific, discrete transponder code for that flight as part of an ATC clearance.
  - 3.4.7 The pilot of an IFR aircraft flying in the New Zealand FIR, but not yet in receipt of an ATC clearance, must set code 2000.
  - 3.4.8 The pilot of an IFR aircraft flying in the Auckland Oceanic FIR must set code 2000 unless a specific transponder code has been specified by an ATS unit.
  - 3.4.9 A limited number of transponder codes are available for allocation to VFR aircraft on cross-country flights. When filing a VFR flight plan via IFIS, the pre-allocated code will be shown in the message acknowledging acceptance of the filed flight plan. When filing via FAX or by phone with the National Briefing Office, no acknowledgment of a pre-allocated code will be made.
  - 3.4.10 Application for permanent codes must be made to the National Briefing Office.
  - 3.4.11 The pilots of all VFR transponder equipped aircraft, whether on flight plan or not, who have been assigned a discrete aircraft or ATC code, should operate that code at all times, unless otherwise instructed by ATC, or when an emergency SSR code is required. The pilots of other VFR aircraft should set the code indicated in Table ENR 1.6-1.
  - 3.4.12 The pilot of an aircraft which is being subjected to unlawful interference, or the threat of unlawful interference, must endeavour to advise ATS of the fact, together with details of any subsequent deviation from the current flight plan and any other significant factors affecting the operation. This enables ATS to give priority to the aircraft and to alert organisations likely to be involved. The following procedures should be followed:
    - (a) squawk CODE 7500 MODE A;
    - (b) advise ATS of details in plain language if possible;
    - (c) if unrestricted use of the radio is not possible, insert the phrase "CHANNEL SEVEN FIVE ZERO ZERO" into any RTF transmission after the aircraft's callsign if it is safe and practicable to do so.
  - 3.4.13 Whenever it has been established that an aircraft is transponding on code 7500 the controller will attempt to verify by RTF with the aircraft concerned that the code selection is intentional:
    " ... (CALL SIGN) ... CONFIRM SQUAWKING SEVEN FIVE ZERO ZERO".
  - 3.4.14 If the aircraft is not being subjected to unlawful interference, the pilot should respond to the query by broadcasting that the aircraft is not being subjected to unlawful interference.
  - 3.4.15 If the reply is in the affirmative or if no reply received, this will indicate the aircraft is subjected to unlawful interference.
  - 3.4.16 ATS personnel recognising any indication of unlawful interference to an aircraft will attend promptly to its request. Information pertinent to the safe conduct of the flight will continue to be transmitted and action will be taken to facilitate the conduct of all phases of flight.
  - 3.4.17 ATC radar units are equipped with alarm systems that activate when the aircraft is within radar coverage and the pilot selects the unlawful interference (code 7500), communication failure (code 7600), or emergency transponder code (code 7700).
  - 3.4.18 It is possible to unintentionally select these codes momentarily when changing the transponder from one code to another. To prevent unnecessary activation of the alarm, pilots should set transponders to "STANDBY" while changing transponder codes.
  - 3.4.19 Pilots should set transponders to "STANDBY" while taxiing; then "ON" as late as practicable before take-off; and to "STANDBY" or "OFF" as soon as practicable after landing. In practice, transponders should be turned on only upon entering the active runway for departure and turned off as soon as the aircraft exits the runway after landing.
  - 3.4.20 When turning the transponder on, ensure that the altitude (ALT) selection is made allowing transmission of Mode A (selected code) and Mode C (altitude) data.
  - 3.4.21 Pilots of aircraft operating in the circuit of a controlled aerodrome should only set transponders to "STANDBY" when instructed by ATC, or when such an instruction is included on the aerodrome chart.
  - 3.4.22 Special procedures apply at Auckland INTL; refer Auckland Ground Movements (2) -- ALL RWY page.
  - 3.4.23 When reporting levels under routine procedures or when requested by ATC, pilots must state the current altimeter reading to the nearest 100 ft. This enables the verification of Mode C data transmitted by the aircraft.
  - 3.4.24 If there is a difference of more than 200 ft between the transponder level readout and the reported level, the pilot will be advised to check the altimeter setting. If the difference continues the pilot will be instructed to switch off Mode C.
  - 3.4.25 After verification, Mode C may be used by ATC to ascertain:
    - (a) that aircraft are maintaining assigned levels; or
    - (b) that aircraft have vacated, passed, or reached a level.
  - 3.4.26 Unverified Mode C data will not be used for vertical separation.
  - 3.4.27 Alerts generated by an ACAS (such as TCAS) are being experienced despite correct ATC separation being applied or there is adequate vertical and/or horizontal distance between the aircraft.
  - 3.4.28 Following are suggestions for reducing the number of these alerts:
    - (a) High performance aircraft in the climb or descent should reduce their rate of climb or descent for the last 1000 ft prior to cleared altitude. "Adjust vertical speed" advisories should be followed.
    - (b) Aircraft operating at the lowest IFR cruising level within controlled airspace will be only 500 ft above the upper limit of uncontrolled airspace. Aircraft should review operations at this level if VFR traffic is in the vicinity.
    - (c) When operating by visual reference within, or entering a controlled aerodrome traffic circuit, pilots should operate an ACAS on Traffic Avoidance (TA) mode. This is to avoid unnecessary Resolution Advisory (RA) manoeuvres against controlled traffic where visual, composite visual, 500 ft vertical or runway separation standards that are not considered by an ACAS as being applied. This advice also applies when operating in proximity to uncontrolled aerodromes.
- 3.5 Transponder Failure/Special Procedures
  - 3.5.1 Flights will not be permitted to enter transponder mandatory controlled airspace without a fully operative transponder unless specifically approved by ATC.
  - 3.5.2 Approval to continue to operate within controlled airspace may be granted to flights experiencing partial or complete transponder failure as follows:
    - (a) If the failure is partial, every effort will be made to allow the flight to continue with minimum restriction to its final destination and thereafter to an appropriate repair base.
    - (b) If the failure is complete, the flight is likely to experience some restrictions whilst enroute to the initial destination and may not be allowed to proceed to subsequent destinations via transponder mandatory airspace until transponder repair is effected. If a repair facility is not available at the initial destination then special approval may be given for the flight to proceed via transponder mandatory airspace to an appropriate repair base. Transit to the appropriate repair base may be restricted to periods of low traffic density with possible use of alternative routes to avoid areas of high traffic density.
    - (c) A Ground Mode alert, where the aircraft's transponder does not switch from ground to air mode, will be handled by ATC as a complete transponder failure. ATC will advise when the transponder indicates a Ground Mode alert.
  - 3.5.3 ATC recognises the economic penalties that operators could face and will be as flexible as safety permits in granting special approval.
- 3.6 Transponder Testing
  - 3.6.1 Operational testing of transponders should, if possible, be carried out only in shielded areas or under controlled conditions. Transmissions from transponders operating in Mode A and C under test may be interpreted by ATC radar and aircraft ACAS as stationary aircraft, thereby giving false alerts to controllers and pilots respectively. Transmissions from transponders under test cannot be filtered out by these systems.
  - 3.6.2 If transponder testing in Mode A and C is required to take place in unshielded conditions the following applies:
    - (a) Notify the nearest ATC unit of the intention to test transponders, giving time period involved;
    - (b) Unless a specific code has been issued for use, operate the transponder on codes 0050 - 0057;
    - (c) When testing Mode C output, if possible set to 40,000 ft or above.
    ATC may request a delay where testing may impact on traffic management.