CIVIL AVIATION: SUBSIDIARY LEGISLATION: CIVIL AVIATION (SURVEILLANCE AND COLLISION AVOIDANCE SYSTEM) REGULATIONS
(section 89(1))
(13th June, 2022)
ARRANGEMENT OF REGULATIONS
REGULATION
PART I
Preliminary Provisions
1. Citation
2. Interpretation
3. Application
PART II
General Requirements
4. Requirements for surveillance facility
5. Approval requirement
6. Inspections and audits
7. Siting and installation
8. Classification of surveillance facilities
9. Availability and reliability of surveillance facility
10. Protection of surveillance radio signals from reflectors or diffractors
11. Periodic inspection and testing of surveillance facility
12. Retention of surveillance data
13. Recording and replay of ATS surveillance data
PART III
Secondary Surveillance Radar (SSR)
14. Secondary Surveillance Radar (SSR) operations
15. Commissioning requirements
16. System recording and replay facilities
17. Interrogation modes (ground-to-air)
18. Side-lobe suppression
19. Transponder reply modes (air-to-ground)
20. Mode A reply codes (information pulses)
21. Mode S airborne equipment capability
22. Capability reporting in Mode S squitter
23. Extended Length Message (ELM) transmit power
24. Secondary Surveillance Radar (SSR) Mode-S address (aircraft address)
25. Human factors principles
PART IV
Airborne Collision Avoidance System (ACAS)
26. ACAS I general provisions and characteristics
27. ACAS I signal format
28. Interference control
29. General provisions relating to ACAS II and ACAS III
30. Surveillance performance requirements for ACAS II and ACAS III
31. Traffic advisories
32. Threat detection
33. Resolution Advisories (RAs)
34. Coordination and communication
35. Provisions for ACAS communication with ground stations
36. Provisions for data transfer between ACAS and its Mode S transponder
37. ACAS protocols
38. Signal formats
39. Field description
40. ACAS fields and subfields
41. ACAS equipment characteristics
42. Antenna selection and pressure altitude source
43. ACAS monitoring
44. Requirements for a Mode S transponder used in conjunction with ACAS
45. Data transfer from ACAS to its Mode S transponder
46. Data transfer from Mode S transponder to its ACAS
47. Communication of ACAS information to other ACAS
48. Communication of ACAS information to ground stations
49. Indications to flight crew
50. Performance of ACAS II collision avoidance logic
51. Conditions under which requirements apply
52. Standard range error model
53. Standard bearing error model
54. Standard altimetry error model
55. Standard pilot model
56. Standard encounter model
57. Encounter classes and weights
58. Characteristics of aircraft trajectories in vertical plane
59. Characteristics of aircraft trajectories in horizontal plane
60. ACAS equipage of intruder
61. Compatibility between different collision avoidance logic designs
62. Reduction in risk of collision
63. Compatibility with Air Traffic Management (ATM)
64. Compatible sense selection
65. Deviations caused by ACAS
66. Relative value of conflicting objectives
67. ACAS hybrid surveillance using extended squitter position data
68. Validation
69. Supplementary active interrogations
70. Near threat
71. Revalidation and monitoring
72. Full active surveillance
73. ACAS operation with an improved receiver Minimum Triggering Level (MTL)
PART V
Mode S Extended Squitter
74. Automatic Dependence Surveillance (ADS)-B out requirements
75. Control of ADS-B out operation
76. TIS-B out requirements
77. ADS-B out requirements for surface vehicles
78. Mode S extended squitter receiving system functional requirements
79. Message exchange function
80. Report assembler function
81. ADS-B report types
82. TIS-B report types
83. Report time of applicability
84. Reporting requirements
85. Interoperability
PART VI
Multilateration (MLAT) Systems
86. Functional requirements
87. Protection of radio frequency environment
88. Performance requirements
PART VII
Technical Requirements for Airborne Surveillance Applications
89. Traffic data functions
90. Displaying traffic
PART VIII
General Provisions
91. Application for exemptions
92. Drug and alcohol testing and reporting
93. Change of name
94. Change of address
95. Replacement of documents
96. Use and retention of documents and records
97. Reports of violation
98. Failure to comply with direction
PART IX
Offences and Penalties
99. Penalties
S.I. 72, 2022.
PART I
Preliminary Provisions (regs 1-3)
These Regulations may be cited as the Civil Aviation (Surveillance and Collision Avoidance Systems) Regulations.
In these Regulations unless the context otherwise requires—
“Airborne Collision Avoidance System (ACAS)” means an aircraft system based on Secondary Surveillance Radar (SSR) transponder signals which operates independently of ground-based equipment to provide advice to the pilot on potential conflicting aircraft that are equipped with SSR transponders;
“ACAS I” means an ACAS which provides information an aid to “see and avoid” action but does not include the capability for generating resolution advisories (RAs);
“ACAS II” means an ACAS which provides vertical resolution advisories (RAs) in addition to traffic advisories (TAs);
“ACAS III” means an ACAS which provides vertical and horizontal resolution advisories (RAs) in addition to traffic advisories (TAs);
“ACAS broadcast” means a long Mode S air-air surveillance interrogation (UF = 16) with the broadcast address;
“active RAC (Resolution Advisory Compliments)” means an RAC currently constrains the selection of the RA, RACs that have been received within the last six seconds and have not been explicitly cancelled are active;
“active surveillance” means the process of tracking an intruder by using the information gained from the replies to own ACAS interrogations;
“aircraft address” means a unique combination of 24 bits available for assignment to an aircraft for the purpose of air-ground communications, navigation and surveillance;
“air navigation services” means one or more of the following services provided for air navigation—
(a) air traffic services;
(b) instrument flight procedure design (IFPD) services;
(c) aeronautical information services (AIS);
(d) aeronautical cartographic services;
(e) aeronautical telecommunication services; or
(f) search and rescue services;
“Air Navigation Services Provider (ANSP)” means an entity established for the purpose of providing one or more of the air navigation services as defined in these Regulations;
“altitude crossing RA” means a Resolution Advisory is altitude crossing if own ACAS aircraft is currently at least 30 m (100 ft) below or above the threat aircraft for upward or downward sense advisories, respectively;
“approach angle” means the difference in the ground headings of the two aircraft at closest approach, with 180 degrees defined as head on and 0 degrees defined as parallel;
“Automatic Dependent Surveillance-Broadcast (ADS-B) OUT” means a function on an aircraft or vehicle that periodically broadcasts its state vector (position and velocity) and other information derived from on-board systems in a format suitable for ADS-B IN capable receivers;
“Automatic Dependent Surveillance-Broadcast (ADS-B) IN” means a function that receives surveillance data from ADS-B OUT data sources;
“Automatic Dependent Surveillance-Broadcast (ADS-B) IN” means a function that receives surveillance data from ADS-B OUT data sources;
“climb RA” means a positive RA recommending a climb but not an increased climb;
“closest approach” means the occurrence of minimum range between own ACAS aircraft and the intruder. A range at closest approach is the smallest range between the two aircraft and time of closest approach is the time at which this occurs;
“collision avoidance logic” means the sub-system or part of ACAS that analyses data relating to an intruder and own aircraft, decides whether advisories are appropriate and, if so, generates the advisories, and it includes the following functions—
(a) range and altitude tracking;
(b) threat detection and RA generation; and
(c) it excludes surveillance;
“coordination” means the process by which two ACAS-equipped aircraft select compatible Resolution Advisories (RAs) by the exchange of Resolution Advisory Complements (RACs);
“coordination interrogation” means a Mode S Interrogation (uplink transmission) radiated by ACAS II or III and containing a resolution message;
“coordination reply” means a Mode S reply (downlink transmission) acknowledging the receipt of a coordination interrogation by the Mode S transponder that is part of an ACAS II or III installation;
“corrective RA” means a Resolution Advisory (RA) that advises the pilot to deviate from the current flight path;
“crossing encounter” means an encounter in which the altitude separation of the two aircraft exceeds 100 ft at the beginning and at the end of the encounter window, and the relative vertical position of two aircraft at the end of the encounter window is reversed from that at the beginning of the encounter window;
“cycle” means one complete pass through the sequence of functions executed by ACAS II or ACAS III, nominally once a second;
“descend RA” means a positive RA recommending a descent but not an increased descent;
“established track” means a track generated by ACAS air-air surveillance that is treated as the track of an actual aircraft;
“encounter” for the purposes of defining the performance of the collision avoidance logic, an encounter consists of two simulated aircraft trajectories, the horizontal coordinates of the aircraft represent the actual position of the aircraft, but the vertical coordinate represents an altimeter measurement of altitude;
“encounter class” means encounters classified according to whether the aircraft are transitioning at the beginning and end of the encounter window, and whether or not the encounter is crossing;
“encounter window” means the time interval [tca – 40 s, tca + 10 s];
“extended hybrid surveillance” means the process of using qualified ADS-B airborne position messages via 1 090 MHz extended squitter without validating 1 090 extended squitter data for the track by ACAS active interrogations;
“Horizontal Miss Distance (HMD)” means the minimum horizontal separation observed in an encounter;
“human factors principles” means principles which apply to design, certification, training, operations and maintenance and which seek safe interface between the human and other system components by proper consideration to human performance;
“hybrid surveillance” means the process of using a combination of active surveillance and passive surveillance with validated data to update an ACAS track in order to preserve ACAS independence;
“increased rate RA” means an RA with a strength that recommends increasing the altitude rate to a value exceeding that recommended by a previous climb or descend RA;
“intruder” means an SSR transponder-equipped aircraft within the surveillance range of ACAS for which ACAS has an established track;
“MU” means a designator Message, Airborne Collision Avoidance System in the message field or in short MU field;
“Multilateration (MLAT) System” means a group of equipment configured to provide position derived from the Secondary Surveillance Radar (SSR) transponder signals (replies or squitters) primarily using Time Difference of Arrival (TDOA) techniques. Additional information, including identification, can be extracted from the received signals;
“original trajectory” means the original trajectory of an ACAS-equipped aircraft followed by the aircraft in the same encounter when it was not ACAS-equipped;
“original rate” means the original rate of an ACAS-equipped aircraft at any time is its altitude rate at the same time when it followed the original trajectory;
“own aircraft” means an aircraft—
(a) fitted with an ACAS that is the subject of the discourse;
(b) which an ACAS is to protect against possible collisions; and
(c) which may enter a manoeuvre in response to an ACAS indication;
“passive surveillance” means the process of tracking another aircraft without interrogating it, by using the other aircraft’s extended squitters (ACAS uses the information obtained via 1090 MHz extended squitter to monitor the need for active surveillance only. Passive surveillance applies to both hybrid and extended hybrid surveillance);
“positive RA” means a Resolution Advisory that advises the pilot either to climb or to descend (applies to ACAS II);
“potential threat” means an intruder deserving special attention either because of its proximity to own aircraft or because successive range and altitude measurements indicate that it could be on a collision or near-collision course with own aircraft, and the warning time provided against a potential threat is sufficiently small that a Traffic Advisory (TA) is justified but not so small that a RA would be justified;
“Radio Frequency (RF)” means a measured unit called hertz (Hz), which represent the number of cycles per second when a radio wave is transmitted from one point to the other;
“RA sense” means the sense of an ACAS II RA is “upward” if it requires climb or limitation of descent rate and “downward” if it requires descent or limitation of climb rate, and it can be both upward and downward simultaneously if it requires limitation of the vertical rate to a specified range;
“required rate” means for the standard pilot model, the required rate is that closest to the original rate consistent with the RA;
“Resolution Advisory (RA)” means an indication given to the flight crew recommending—
(a) a manoeuvre intended to provide separation from all threats; or
(b) a manoeuvre restriction intended to maintain existing separation;
“Resolution Advisory Complement (RAC)” means information provided by one ACAS to another via a Mode S interrogation in order to ensure complementary manoeuvres by restricting the choice of manoeuvres available to the ACAS receiving the RAC;
“Resolution Advisory Complements record (RAC record)” means a composite of all currently active vertical RACs (VRCs) and horizontal RACs (HRCs) that have been received by ACAS. This information is provided by one ACAS to another ACAS or to a Mode S ground station via a Mode S reply;
“reversed sense RA” means an RA that has had its sense reversed;
“Secondary Surveillance Radar (SSR)” means a surveillance radar system which uses transmitters/receivers (interrogators) and transponders;
“sensitivity level (S)” means an integer defining a set of parameters used by the Traffic Advisory and collision avoidance algorithms to control the warning time provided by the potential threat and threat detection logic, as well as the values of parameters relevant to the RA selection logic;
“surveillance radar” means radar equipment used to determine the position of an aircraft in range and azimuth;
“threat” means an intruder deserving special attention either because of its proximity to own aircraft or because successive range and altitude measurements indicate that it could be on a collision or near-collision course with own aircraft, and the warning time provided against a threat is sufficiently small that an RA is justified;
“Time Difference of Arrival (TDOA)” means the difference in relative time that a transponder signal from the same aircraft (or ground vehicle) is received at different receivers;
“Traffic Advisory (TA)” means an indication given to the flight crew that a certain intruder is a potential threat;
“Traffic Information Service – Broadcast (TIS-B) IN” means a surveillance function that receives and processes surveillance data from TIS-B OUT data sources;
“Traffic Information Service – Broadcast (TIS-B) OUT” means a function on the ground that periodically broadcasts the surveillance information made available by ground sensors in a format suitable for TIS-B IN capable receivers;
“transitioning aircraft” means an aircraft having an average vertical rate with a magnitude exceeding 400 feet per minute (ft/min), measured over some period of interest;
“transponder occupancy” means a state of unavailability of the transponder from the time it detects an incoming signal that appears to cause some action or from the time of a self-initiated transmission, to the time that it is capable of replying to another interrogation;
“turn extent” means an aircraft’s ground heading at the end of a turn minus its ground heading at the beginning of the turn;
“validation” means the process of verifying the relative position of an intruder using passive information via 1090 MHz extended squitter by comparing it to the relative position obtained by Airborne Collision Avoidance System active interrogation;
“Vertical Miss Distance (VMD)” means the minimum vertical separation observed in encounter; and
“warning time” means the time interval between potential threat or threat detection and closest approach when neither aircraft accelerates.
These Regulations shall apply to a person providing surveillance services within a designated airspace and at an aerodrome.
PART II
General Requirements (regs 4-13)
4. Requirements for surveillance facility
The minimum requirements for planning, installation, commissioning, training, operation and maintenance of the surveillance facility shall conform to these Regulations.
(1) A person who wishes to operate a surveillance facility or system shall apply in writing to the Authority for an approval of the surveillance facility or system.
(2) The Authority may approve surveillance facility or system in a designated airspace and aerodrome.
(3) A person shall not provide or operate a surveillance facility or system in the designated airspace or aerodrome unless the surveillance facility or system has been approved by the Authority.
(4) An Air Navigation Service Provider shall notify the Authority of his or her intention to procure, install, use, decommission, upgrade or relocate any surveillance facility in the designated airspace or aerodrome not less than 30 days prior to the date of procuring, installing, decommissioning, upgrading or relocating such surveillance system.
(5) The Authority may approve installation, use, decommissioning, upgrading or relocation of all surveillance facilities in the designated airspace and aerodromes.
(1) The Authority may carry out safety inspections and audits on a surveillance facility, document or record to determine compliance with these Regulations.
(2) An inspector of the Authority shall have unrestricted access to a facility, installation, record or document of an Air Navigation Service Provider to determine compliance with these Regulations and required procedures.
An Air Navigation Service Provider shall before establishing any surveillance equipment site, whether temporary or permanent obtain approval of the site from the Authority.
8. Classification of surveillance facilities
The following list classifies the type of facilities used for the provision of aeronautical surveillance service—
(a) flight data processing facility;
(b) flight information facility;
(c) radar data processing facility;
(d) primary surveillance radar facility;
(e) Secondary Surveillance Radar facility;
(f) surface movement radar facility;
(g) Multilateration (MLAT) surveillance facility;
(h) precision runway monitor facility;
(i) automatic dependent surveillance system facility;
(j) uninterruptible and emergency power supply facility;
(k) essential service in a building and in equipment shelter housing facility (electrical power supply, air-conditioning, and security facility); and
(l) data recording facility.
9. Availability and reliability of surveillance facility
(1) An Air Navigation Service Provider shall establish an overall operation and maintenance plan for surveillance system which shall meet the safety, operational requirement and performance specification of a surveillance facility.
(2) The operation and maintenance plan in subregulation (1) shall include—
(a) a procedure for the periodic inspection and testing of each facility to verify that it meets the specified operational and performance specifications;
(b) details of flight test, such as the standards and procedures to be used and flight test interval, which shall be in compliance with guidelines in International Civil Aviation Organisation Doc 8071 or any other appropriate International Civil Authority Organisation document;
(c) the interval between periodic inspection and flight test and the basis for that interval, and when the interval is changed, the reasons for such change shall be documented;
(d) the operation and maintenance instructions for each facility;
(e) an analysis of the number of personnel required to operate and maintain each surveillance facility, taking into account the workload required;
(f) the corrective plan and procedures for each surveillance facility, including whether the repair of modules and components are undertaken in house or by equipment manufacturers; and
(g) the spare support plan for each facility.
(3) An Air Navigation Service Provider shall be responsible for the provision of surveillance service and facility, to ensure that the surveillance data necessary for the safe, regular and efficient operation of air navigation is accurate and available.
(4) An Air Navigation Service Provider shall establish and document performance measures to be achieved for each surveillance system in terms of the following parameters—
(a) availability;
(b) reliability;
(c) accuracy;
(d) availability;
(e) integrity;
(f) Mean Time Between Failure (MTBF); and
(g) Mean Time to Repair (MTTF).
(5) The parameters in subregulation (4), shall be derived or measured from—
(a) the configuration of each service; or
(b) the known performance of each service.
(6) An Air Navigation Service Provider shall, describe in the operations manual the method used to calculate each of the values in subregulation (7).
(7) The integrity values or characteristics shall be given for each facility that forms part of the surveillance service.
(8) An Air Navigation Service Provider shall ensure a surveillance facility is connected to a power and a standby power supply, to ensure continuity of operation appropriate to the service being provided.
10. Protection of surveillance radio signals from reflectors or diffractors
(1) An Air Navigation Service Provider shall prevent any development near a radio site that may have a potential to reflect or diffract surveillance radio signals.
(2) An Air Navigation Service Provider shall ensure that the following radar do not reflect or diffract surveillance radio signals—
(a) Primary Radar – Line of sight from the installation to surveillance areas or volume shall be maintained. No obstruction shall penetrate the volume above the radar platform for a distance of 4 600 m from the installation or prevent line-of-sight from the installation to aircraft during the approach phase and movements on runways;
(b) Secondary Surveillance Radar – Line of sight from the installation to surveillance areas or volume shall be maintained to a distance of 15 km. No obstruction shall penetrate the volume above the radar platform for a distance of 4 600 m from the installation or prevent line-of-sight from the installation to aircraft during the approach phase and movements on runways;
(c) Surface Movement Radar – Line-of-sight shall be maintained at ground level from the radar to all areas within the aerodrome boundary where any movement of aircraft, personnel or vehicles can occur;
(d) Multilateration (MLAT) – Line of sight from the installation to surveillance areas or volume shall be maintained. No obstruction shall penetrate the volume above the surveillance platform for a distance of 4 600 m from the installation or prevent line-of-sight from the installation to aircraft during the approach phase and movements on runway; and
(e) Automatic Dependent Surveillance – Broadcast (ADS-B) Line of sight from the installation to surveillance areas or volume shall be maintained. No obstruction shall penetrate the volume above the surveillance platform for a distance of 4 600 m from the installation or prevent line-of- sight from the installation to aircraft during the approach phase and movements on runways.
(3) An Air Navigation Service Provider shall consult the Authority regarding the non-use of designs or certain materials considered to be reflective or that could cause attenuation of the signal, such as metal reinforced glass, metal cladding, chain-link fencing, on elevations facing the surveillance installations shall be undertaken.
11. Periodic inspection and testing of surveillance facility
An Air Navigation Service Provider shall establish a procedure for the periodic inspection and testing of a surveillance system, to verify that each facility meets the applicable operational requirements and performance specifications for that facility.
12. Retention of surveillance data
An Air Navigation Service Provider shall—
(a) establish a procedure for retention and release of surveillance data;
(b) retain recording of surveillance for a period of at least 30 days; and
(c) retain recordings that are pertinent to an accident or incident investigations for longer periods until it is evident that they will no longer be required.
13. Recording and replay of ATS surveillance data
(1) An Air Navigation Service Provider shall provide recording equipment capable of automatic recording and replaying of surveillance data from primary and secondary radar equipment or other surveillance systems used as an aid to air traffic service.
(2) A recording equipment shall provide a complete, identified, intelligible and accurate record of surveillance data to be recorded which may be used, in the event of an incident or in any investigation, by the designated Authority.
(3) A recorded surveillance data shall include targets, system settings, time, alerts, alarms and any information necessary for investigation play back.
(4) A replay equipment shall reconstruct the recorded data and shall, accurately reproduce all the features that were displayed, including display settings, at the relevant operational positions at the time of recording.
PART III
Secondary Surveillance Radar (SSR) (regs 14-25)
14. Secondary Surveillance Radar (SSR) operations
When Secondary Surveillance Radar is installed and maintained in operation as an aid to air traffic service, it shall conform to the provisions specified in Schedule 1 of these Regulations, unless otherwise specified.
15. Commissioning requirements
(1) An Air Navigation Service Provider shall carry out a test flight during a system commissioning technical acceptance test.
(2) To assess performance, a test method shall comprise of the following stages—
(a) data collection and observations;
(b) data analysis; and
(c) comparison of results.
(3) A manufacture shall measure the following parameters prior to a test in subregulation (1), being carried out as part of planned maintenance—
(a) horizontal polar diagram;
(b) vertical polar diagram;
(c) antenna gain; and
(d) azimuth squint and skew, that is, distortion of beam shape (squint) or skew (direction) as function of frequency within the operating bandwidth of the antenna.
(4) The results from the measurements in subregulation (3), shall be made available to the user.
16. System recording and replay facilities
An Air Navigation Service Provider shall continuously record radar surveillance data supplied to the display system and establish procedures for retention and utilisation of the recordings for analysis.
17. Interrogation modes (ground-to-air)
(1) An Air Navigation Service Provider shall ensure that an interrogation of air traffic services is performed on the modes specified in paragraph 1.1.1.4.3 and 1.1.2, set out in Schedule 1 and each mode shall be used as follows—
(a) Mode A – to elicit transponder replies for identity and surveillance;
(b) Mode C – to elicit transponder replies for automatic pressure-altitude transmission and surveillance;
(c) Intermode—
(i) Mode A/C/S all-call: to elicit replies for surveillance of Mode A/C transponders and for the acquisition of Mode S transponders, and
(ii) Mode A/C-only all-call: to elicit replies for surveillance of Mode A/C transponders. Mode S transponders do not reply; and
(d) Mode S—
(i) Mode S-only all-call: to elicit replies for acquisition of Mode S transponders,
(ii) Broadcast: to transmit information to all Mode S transponders. No replies are elicited, and
(iii) Selective: for surveillance of, and communication with, individual Mode S transponders. For each interrogation, a reply is elicited only from the transponder uniquely addressed by the interrogation.
(2) The Authority shall coordinate with appropriate national and international authorities to ensure that implementation aspects of the SSR system which permits the SSR system’s optimum use.
(3) The assignment of interrogator identifier codes in areas of overlapping coverage, across international boundaries of flight information regions, shall be the subject of regional air navigation agreements.
(4) The assignment of surveillance identifier codes in areas of overlapping coverage, shall be the subject of regional air navigation agreements.
(5) Mode A and Mode C interrogations shall, be provided by intermode interrogations which elicit Mode A and Mode C replies from Mode A/C transponder.
(6) In areas where improved aircraft identification is necessary to enhance the effectiveness of the air traffic control system, Secondary Surveillance Radar ground facility having Mode S features shall include aircraft identification capability.
(1) A side-lobe suppression shall be provided in accordance with paragraphs 1.1.1.4 and 1.1.1.5 set out in Schedule 1 on all Mode A, Mode C and inter-mode interrogations.
(2) A side-lobe suppression shall be provided in accordance with paragraph 1.1.2.1.5.2.1 set out in Schedule 1 on all Mode S-only all-call interrogations.
19. Transponder reply modes (air-to-ground)
(1) A transponder shall respond to Mode A interrogations in accordance with paragraph 1.1.1.7.12.1 set out in the Schedule 1 and to Mode C interrogations in accordance with the paragraph 1.1.1.7.12.2 set out in Schedule 1.
(2) The pressure-altitude report contained in Mode S replies shall be as specified in paragraph 1.1.1.7.12.2 set out in Schedule 1.
(3) Where the need for Mode C automatic pressure-altitude transmission capability within a specified airspace has been determined, a transponder, when used within the airspace concerned, shall respond to Mode C interrogation with pressure-altitude encoding in the information pulses.
(4) A transponder, regardless of the airspace in which it will be used, shall respond to Mode C interrogations with pressure-altitude information.
(5) The pressure-altitude information provided by Mode S transponder in response to selective interrogations of an aircraft equipped with 7.62 m (25 ft.) or better pressure-altitude sources, shall be reported in 7.62 m (25 ft) increments.
(6) A Mode A/C transponder shall report pressure-altitude encoded in the information pulses in Mode C replies.
(7) A Mode S transponder shall report pressure-altitude encoded in the information pulses in Mode C replies and in the AC field of Mode S replies.
(8) When a Mode S transponder is not receiving more pressure-altitude information from a source with a quantisation of 7.62 m (25 ft) or better increments, the reported value of the altitude shall be the value obtained by expressing the measured value of the uncorrected pressure-altitude of the aircraft in 30.48 m (100 ft) increments, and the Q bit shall be set to 0.
(9) A transponder used within airspace where the need for Mode S airborne capability has been determined, shall also respond to intermode and Mode S interrogations in accordance with the paragraph 1.1.2 set out in Schedule 1.
(10) The requirements for mandatory carriage of Secondary Surveillance Radar Mode S transponder shall—
(a) be based on regional air navigation agreements; and
(b) specify the airspace and the airborne implementation timescales.
(11) The agreements indicated in subregulation (10) shall provide at least a notice of five years.
20. Mode A reply codes (information pulses)
(1) A transponder shall be capable of generating 4096 reply codes conforming to the characteristics in accordance with paragraph 1.1.1.6.2 set out in Schedule 1.
(2) The Authority shall establish the procedures for the allotment of Secondary Surveillance Radar code in conformity with regional air navigation agreements, considering other users of the system.
(3) The following Mode A codes shall be reserved for special purposes—
(a) Code 7700, to provide for recognition of an aircraft in an emergency;
(b) Code 7600, to provide for recognition of an aircraft with radio communication failure; and
(c) Code 7500, to provide for recognition of an aircraft which is being subjected to unlawful interference.
(4) Provisions shall be made in ground decoding equipment, to ensure immediate recognition of Mode A codes 7500, 7600 and 7700.
(5) A Mode A code 0000 shall be reserved for allocation subject to regional agreement, as a general-purpose code.
(6) A Mode A code 2000 shall be reserved to provide recognition of an aircraft which has not received any instructions from air traffic control units to operate the transponder.
21. Mode S airborne equipment capability
(1) A Mode S transponder shall conform to one of the following five levels—
(a) Level 1 transponder shall have the capabilities determined for—
(i) Mode A identity and Mode C pressure-altitude reporting,
(ii) intermode and Mode S all-call transactions,
(iii) addressed surveillance altitude and identity transaction,
(iv) lockout protocols,
(v) basic data protocols except data link capability reporting, and
(vi) air-air service and squitter transactions;
(b) Level 2 transponders shall have capabilities determined in paragraph (a) and those determined for—
(i) standard length communications (Comm-A and Comm-B),
(ii) data link capability reporting, and
(iii) aircraft identification reporting; or
(c) Level 3 transponders shall have capabilities contained in paragraph (b) and also those determined for ground-to-air extended length message communications;
(d) Level 4 transponders shall have capabilities contained in paragraph (c) and those determined for air-to-ground extended length message communications; or
(e) Level 5 transponders shall have capabilities contained in paragraph (d) and those determined for enhanced Comm-B and extended length message communications.
(2) An extended squitter transponder shall have the capabilities in subregulation (1)(b), (c), (d) or (e), and those capabilities determined for extended squitter operation and ACAS cross-link operation.
(3) A transponder with capabilities referred to under subregulation (2) shall be designated with a suffix “e”.
(4) A transponder with the ability to process surveillance identifier codes shall have the capabilities in subregulation (1)(a), (b), (c), (d) or (e) and those determined for surveillance identifier code operation.
(5) A transponder with capability referred to under subregulation (4) shall be designated with a suffix “s”.
(6) A surveillance identifier code capability shall be provided in accordance with subregulation (4) and (5) for a Mode S transponder installed on or after 1 January 2003, and by all Mode S transponders by 1 January 2005.
(7) An extended squitter non-transponder device that is capable of broadcasting extended squitter that is not part of a Mode S transponder shall conform to all the 1090 MHz RF signals in space requirements specified for a Mode S transponder, except for transmit power levels for the identified equipment class in regulation 73.
(8) A Mode S transponder used by international civil air traffic shall conform to requirements of Level 2 in subregulation (1)(b).
(9) A Mode S transponder installed on an aircraft with gross mass in excess of 5 700 kg or a maximum cruising true airspeed capability in excess of 463 km/h (250 kt) shall operate with antenna diversity as provided for in paragraph 1.1.2.10.4 set out in Schedule 1:
Provided the aircraft individual certificate of airworthiness is first issued on or after 1 January 1990, or a Mode S transponder carriage is required based on regional air navigation agreement in accordance with regulation 19(10) and (11).
22. Capability reporting in Mode S squitter
(1) A capability reporting in a Mode S acquisition squitter unsolicited downlink transmissions shall be provided in accordance with the paragraph 1.1.2.8.5.1 set out in Schedule 1 for all Mode S transponders installed on or after 1 January 1995.
(2) A transponder equipped for extended squitter operation shall, have a means to disable acquisition squitter when extended squitter are being emitted.
23. Extended Length Message (ELM) transmit power
A transponder manufactured before 1 January 1999 shall be permitted to transmit a burst of 16 Extended Length Message segments at a minimum power level of 20 dBW, in order to facilitate the conversion of existing Mode S transponders, to include a full Mode S capability.
24. Secondary Surveillance Radar (SSR) Mode-S address (aircraft address)
A Secondary Surveillance Radar Mode S address shall, be one of 16 777 214 24 bit aircraft addresses allocated by International Civil Aviation Organisation to the state of registry or common mark registering Authority and assigned in accordance with paragraph 1.1.2.4.1.2.3.1.1 set out in Schedule 1.
The manufacture shall ensure that—
(a) human factors principles shall be observed in the design and certification of surveillance radar and collision avoidance system;
(b) transponder controls which is not intended to be operated in flight shall not be directly accessible to the flight crew;
(c) the operation of transponder controls, intended for use during flight shall be evaluated to ensure they are logical and tolerant to human error;
(d) unintentional transponder mode switching is minimised where transponder functions are integrated with other system controls; and
(e) the flight crew shall always have access to the information of the operational state of the transponder.
PART IV
Airborne Collision Avoidance System (ACAS) (regs 26-73)
26. ACAS I general provisions and characteristics
An Airborne Collision Avoidance System I shall perform the following functions—
(a) surveillance of nearby Secondary Surveillance Radar transponder-equipped aircraft; and
(b) provide indications to the flight crew identifying the approximate position of nearby aircraft as an aid to visual acquisition.
The Radio Frequency characteristics of all Airborne Collision Avoidance System I signal shall conform to provisions of paragraphs 1.1.1.1 to 1.1.1.6, and 1.1.2.1 and 1.1.2.4 set out in Schedule 1.
(1) The effective radiated power of an Airborne Collision Avoidance System I transmission at 0-degree elevation relative to the longitudinal axis of the aircraft shall not exceed 24 dBW.
(2) When Airborne Collision Avoidance System I is not transmitting an interrogation, the effective radiated power in any direction shall not exceed 70 dBm.
(3) An Airborne Collision Avoidance System I interrogator shall control its interrogation rate and power or both in all Secondary Surveillance Radar modes to minimise interference effects.
(4) An Airborne Collision Avoidance System I shall monitor the rate that own transponder replies to interrogations to ensure that subregulation (7) is complied with.
(5) An Airborne Collision Avoidance System I shall count the number of Airborne Collision Avoidance System II and Airborne Collision Avoidance System III interrogators in the vicinity to ensure that subregulations (7) or (8) are complied with.
(6) An Airborne Collision Avoidance System I count in subregulation (5) shall be—
(a) obtained by monitoring Airborne Collision Avoidance System broadcasts (UF = 16); and
(b) updated as the number of distinct Airborne Collision Avoidance System aircraft addresses received within the previous 20 seconds period at a minimum frequency of at least 1 Hz.
(7) The interrogator power shall not exceed the limits defined in paragraph 1 set out in Schedule 2.
(8) An Airborne Collision Avoidance System I that uses Mode S interrogations shall not cause greater interference effects than an Airborne Collision Avoidance System I using Mode A/C interrogations only.
29. General provisions relating to ACAS II and ACAS III
(1) An Airborne Collision Avoidance System shall perform the following functions—
(a) surveillance;
(b) generation of Traffic Advisories;
(c) threat detection;
(d) generation of Resolution Advisories;
(e) coordination; and
(f) communication with ground stations.
(2) An Airborne Collision Avoidance System equipment shall perform functions in subregulation (1)(b), (c), (d) and (e) on each cycle of operation and the duration of the cycle shall not exceed 1.2 seconds.
30. Surveillance performance requirements for ACAS II and ACAS III
(1) An Airborne Collision Avoidance System shall—
(a) interrogate SSR Mode A/C and Mode S transponders in other aircraft and detect the transponder replies;
(b) measure the range and relative bearing of responding aircraft and using these measurements and information conveyed by transponder replies;
(c) estimate the relative positions of each responding aircraft; and
(d) include provisions for achieving such position determination in the presence of ground reflections, interference and variations in signal strength.
(2) An Airborne Collision Avoidance System shall generate an established track, with at least a 0.90 probability that the track is established 30 seconds before closest approach, on aircraft equipped with transponders, when all the following conditions are satisfied—
(a) the elevation angles of these aircraft are within ±10 degrees relative to the Airborne Collision Avoidance System aircraft pitch plane;
(b) the magnitudes of these aircraft’s rates of change of altitude are less than or equal to 51 m/s (10 000 ft/min);
(c) the transponders and antennas of these aircraft meet the standards of Part IV of these Regulations;
(d) the closing speeds and directions of these aircraft, the local density of SSR transponder-equipped aircraft and the number of other Airborne Collision Avoidance System interrogators in the vicinity, as determined by monitoring Airborne Collision Avoidance System broadcasts, satisfy the conditions specified in Table 1-1 set out in Schedule 2; and
(e) the minimum slant range is equal to or greater than 300 m (1 000 ft).
(3) An Airborne Collision Avoidance System shall continue to provide surveillance with no abrupt degradation in track establishment probability, as any one of the condition bounds defined in Schedule 1.1.1 is exceeded.
(4) An Airborne Collision Avoidance System shall not track Mode S aircraft that report that it is on the ground.
(5) An Airborne Collision Avoidance System shall achieve the required tracking performance when—
(a) the average SSR Mode A/C asynchronous reply rate from a transponder in the vicinity of the Airborne Collision Avoidance System aircraft is 240 replies per second; and
(b) the peak interrogation rate received by an individual transponder under surveillance is 500 per second.
(6) The probability that an established Mode A/C track does not correspond in range and altitude, if reported to an actual aircraft, shall be less than 10-2, and for an established Mode S track this probability shall be less than 10-6:
Provided that these limits are not exceeded in any traffic environment.
(7) The range shall be measured with a resolution of 14.5 m (1/128 NM) or better.
(8) The errors in the relative bearings of the estimated positions of intruders shall not exceed 10 degrees rms.
(9) The effective radiated power of an Airborne Collision Avoidance System transmission at 0-degree elevation relative to the longitudinal axis of the aircraft shall not exceed 27 dBW.
(10) When Airborne Collision Avoidance System is not transmitting an interrogation, the effective radiated power in any direction shall not exceed -70 dBm.
(11) An Airborne Collision Avoidance System interrogator operating below a pressure-altitude of 5 490 m (18 000 ft) shall control its interrogation rate or power to conform with the following specific inequalities—
(a) Airborne Collision Avoidance System shall count the number of other Airborne Collision Avoidance System II and III interrogators in the vicinity to ensure that the interference limits are met, and this count shall be obtained by monitoring Airborne Collision Avoidance System broadcasts (UF = 16), and each Airborne Collision Avoidance System shall monitor such broadcast interrogations to determine the number of other Airborne Collision Avoidance System within detection range; and
(b) Airborne Collision Avoidance System shall adjust its interrogation rate and interrogation power such that the following inequalities remain true, except as provided in Schedule 2—
(i) all air-to-air coordination interrogations shall, be transmitted at full power and these interrogations shall be excluded from the summations of Mode S interrogations in the left-hand terms of inequalities (1) and (2) in Schedule 2 for the duration of the RA,
(ii) when the Airborne Collision Avoidance System aircraft indicates that it is on the ground, Airborne Collision Avoidance System interrogations shall be limited by setting the number of other Airborne Collision Avoidance System II and III aircraft (n
) count in the interference limiting inequalities to a value that is three times the value obtained based on Airborne Collision Avoidance System broadcasts received with a transponder receiver threshold of -74 dBm, and when a Mode A/C interrogation power is reduced because of interference limiting, the Mode A/C interrogation power in the forward beam shall be reduced first until the forward sequence matches the right and left sequences, and the forward, right and left interrogation powers shall then sequentially be reduced until they match the rear interrogation power, and further reduction of Mode A/C power shall be accomplished by sequentially reducing the forward, side and rear interrogation powers, and
(iii) when transmissions from Airborne Collision Avoidance System units above 5 490 m (18 000 ft) altitude, and each Airborne Collision Avoidance System interrogator operating above a pressure-altitude of 5 490 m (18 000 ft) shall control its interrogation rate or power or both such that inequalities (1) and (3) in Schedule 2 remain true when na ‘>and are equal to 1, except as provided in subregulation (11)(b)(i).
(1) An Airborne Collision Avoidance System shall provide traffic advisories to alert the flight crew to potential threats.
(2) The Traffic advisories in subregulation (1) shall be accompanied by an indication of the approximate relative position of potential threats to facilitate visual acquisition.
(3) When a potential threat is shown on a traffic display, it shall be displayed in amber or yellow.
(4) When any Resolution Advisory or Traffic Advisory is displayed, proximate traffic within 11 km (6 NM) range and, if altitude reporting, ±370 m (1 200 ft) altitude shall be displayed.
(5) The proximate traffic in subregulation (4) shall be distinguished by color or symbol type from threats and potential threats, which shall be more prominently displayed.
(6) When any Resolution Advisory or Traffic Advisory is displayed, visual acquisition of the threat or potential threat shall not be adversely affected by the display of proximate traffic or other data unrelated to collision avoidance.
(7) The criteria for a Traffic Advisory shall be satisfied before that of a Resolution Advisory.
(8) The minimum Traffic Advisory warning time for intruders reporting altitude shall not be 20 seconds greater than the minimum warning time for the generation of the Resolution Advisory.
(1) An Airborne Collision Avoidance System shall evaluate appropriate characteristics of each intruder to determine whether it is a threat.
(2) The minimum characteristics of an intruder that are used to identify a threat shall include—
(a) tracked altitude;
(b) tracked rate of change of altitude;
(c) tracked slant range;
(d) tracked rate of change of slant range; and
(e) sensitivity level of intruder’s Airborne Collision Avoidance System, Si.
(3) For an intruder not equipped with Airborne Collision Avoidance System II or Airborne Collision Avoidance System III, Surveillance Identifier shall be set to 1.
(4) The minimum characteristics of own aircraft that is used to identify a threat shall include—
(a) altitude;
(b) rate of change of altitude; and
(c) sensitivity level of own Airborne Collision Avoidance System.
(5) An Airborne Collision Avoidance System shall be capable of operating at a number of sensitivity levels, and these shall include—
(a) S = 1, a “standby” mode in which the interrogation of other aircraft and all advisories are inhibited;
(b) S = 2, a “TA only” mode in which RAs are inhibited; and
(c) S = 3-7, further levels that enable the issue of RAs that provide the warning times indicated in Table 2.2 set out Schedule 2 as well as TAs.
(6) The selection of own Airborne Collision Avoidance System sensitivity level shall be determined by sensitivity level control commands which shall be accepted from following sources—
(a) SLC command generated automatically by Airborne Collision Avoidance System based on altitude band or other external factors;
(b) SLC command from pilot input; and
(c) SLC command from Mode S ground stations.
(7) The acceptable SLC command codes shall include—
| Coding
|
|
|
(a) for SLC based on altitude band |
2-7
|
|
(b) for SLC from pilot input |
0,1,2
|
|
(c) for SLC from Mode S ground stations |
0,2-6.
|
(8) Where an Airborne Collision Avoidance System selects an SLC command based on altitude, hysteresis shall be applied to the nominal altitude thresholds which SLC command value changes are required as follows—
(a) for a climbing Airborne Collision Avoidance System aircraft, the SLC command shall be increased at the appropriate altitude threshold plus the hysteresis value; and
(b) for a descending Airborne Collision Avoidance System aircraft, the SLC command shall be decreased at the appropriate altitude threshold minus the hysteresis value.
(9) An SLC command set by the pilot at the value 0 shall, indicate the selection of the “automatic” mode for which the SLC shall be based on the other commands.
(10) For a SLC commands transmitted via a Mode S ground station, the value 0 shall indicate that the station concerned is not issuing a SLC command and that an SLC shall be based on the other commands, including non-0 commands from other Mode S ground station, and the Airborne Collision Avoidance System shall not process an uplinked SLC value of 1.
(11) ATS authorities shall ensure that procedures are in place to inform pilots of any ATS selected SLC command code other than 0.
(12) An Airborne Collision Avoidance System sensitivity level shall be set to the smallest non-0 SLC command received from any of the sources listed in subregulations (5) to (11).
(13) When the sensitivity level of own Airborne Collision Avoidance System is three or greater, the parameter values used for RA generation that depend on sensitivity level, shall be based on the greater of the sensitivity level of own Airborne Collision Avoidance System, and the sensitivity level of the intruder’s Airborne Collision Avoidance System, Si.
(14) The parameter values used for Traffic Advisory generation that depend on sensitivity level shall be selected on the same basis as those for RAs (1.4) except, when an SLC command with a value of 2, “TA only” mode, has been received from either the pilot or a Mode S ground station. In this case, the parameter values for TA generation shall retain the values they would have had in the absence of the SLC command from the pilot or Mode S ground station.
33. Resolution Advisories (RAs)
(1) An Airborne Collision Avoidance System shall generate an RA for all threats except, where—
(a) it is not possible to select an RA that can be predicted to provide adequate separation because of uncertainty in the diagnosis of the intruder’s flight path; or
(b) there is a high risk that a manoeuvre by the threat will negate the RA.
(2) All threats that are shown on a traffic display shall be displayed in red.
(3) Once an RA has been generated against a threat, it shall be maintained or modified until tests that are less stringent than those for threat detection indicate on two consecutive cycles that the RA may be cancelled, at which time it shall be cancelled.
(4) An Airborne Collision Avoidance System shall generate the RA—
(a) that is predicted, to provide adequate separation from all threats;
(b) that has the least effect on the current flight path of the Airborne Collision Avoidance System aircraft; and
(c) consistent with other provisions in these Regulations.
(5) An RA shall not recommend or continue to recommend a manoeuvre or manoeuvre restriction that, considering the range of probable threat trajectories, is more likely to reduce separation than increase it.
(6) A new Airborne Collision Avoidance System installations made after 1 January 2014 shall monitor own aircraft’s vertical rate to verify compliance with the RA sense.
(7) An Airborne Collision Avoidance System shall—
(a) stop assuming compliance where non-compliance is detected and shall assume the observed vertical rate;
(b) be compliant with the requirement in paragraph (a) and subregulation (6);
(c) comply with the requirements set out in subregulation (6) and paragraph (a); and
(d) generate an RA consistent with the performance capability of the aircraft.
(8) A descend RA shall not be generated or maintained when own aircraft is below 300 m (1 000 ft) above ground level.
(9) An Airborne Collision Avoidance System shall not operate in sensitivity levels 3-7 when own aircraft is below 300 m (1 000 ft) above ground level.
(10) An Airborne Collision Avoidance System shall not reverse the sense of an RA from one cycle to the next, except as permitted in subregulation (11) to ensure coordination or when the predicted separation at closest approach for the existing sense is inadequate.
(11) Where an RA component received from an equipped threat is incompatible with the current RA sense, an Airborne Collision Avoidance System shall modify the RA sense to conform with the received RAC if own aircraft address is higher in value than that of the threat.
(12) An Airborne Collision Avoidance System shall not modify an RA sense, in a way that makes the RA sense incompatible with an RAC received from an equipped threat if own aircraft address is higher in value than that of the threat.
(13) Subject to the requirement that a descend RA is not generated at low altitude, an RA shall, not be modified if the time to closest approach is too short to achieve a significant response or if the threat is diverging in range.
(14) An RA shall not be weakened if it is likely that it would subsequently need to be strengthened.
(15) When an RAC is received from a threat before the Airborne Collision Avoidance System generates an RAC for that threat, the RA generated shall be compatible with the RAC:
Provided that such an RA is more likely to reduce separation than increase it and own aircraft address is lower in value than that of the threat.
(16) The RA sense, strength and attributes on each cycles of an RA, shall be encoded in the active RA subfield, and when the active RA subfield has not been refreshed for an interval of 6 seconds, it shall be set to 0, along with the MTE subfield in the same message.
(17) The system delay from receipt of the relevant SSR reply to presentation of an RA sense and strength to the pilot shall be short and shall not exceed 1.5 seconds.
34. Coordination and communication
(1) An Airborne Collision Avoidance System shall, in a multi-aircraft situation, coordinate with each equipped threat individually.
(2) An Airborne Collision Avoidance System shall prevent simultaneous access to stored data by concurrent processes, during resolution message processing.
(3) An Airborne Collision Avoidance System cycle shall transmit a coordination interrogation to each equipped threat, unless generation of an RA is delayed because it is not possible to select an RA that can be predicted to provide adequate separation.
(4) When an RAC has been received from a threat before Airborne Collision Avoidance System selects an RAC for that threat, the selected RAC shall be compatible with the received RAC unless—
(a) no more than three cycles have elapsed since the RAC was received;
(b) the RAC is altitude-crossing; and
(c) own aircraft address is lower in value than that of the threat, in which case Airborne Collision Avoidance System shall select its RA independently.
(5) Where an RAC received from an equipped threat is incompatible with the RAC selected by Airborne Collision Avoidance System for that threat, the Airborne Collision Avoidance System shall modify the selected RAC to be compatible with the received RAC if own aircraft address is higher in value than that of the threat.
(6) An Airborne Collision Avoidance System shall, within the cycle during which an intruder ceases to be a reason for maintaining the RA, send a resolution message to that intruder by means of a coordination interrogation.
(7) A resolution message sent under subregulation (6) shall include the cancellation code for the last RAC sent to that intruder while it was a reason for maintaining the RA.
(8) An Airborne Collision Avoidance System coordination interrogation shall be transmitted until a coordination reply is received from the threat, up to a minimum of six and not more than 12 attempts.
(9) The successive interrogations in subregulation (7) shall be nominally equally spaced over a period of 100 ±5 ms.
(10) An Airborne Collision Avoidance System shall continue its regular processing sequence when the maximum number of attempts are made, and no reply is received.
(11) An Airborne Collision Avoidance System shall provide parity protection for all fields in the coordination interrogation that convey RAC information.
(12) When an Airborne Collision Avoidance System reverses its sense against an equipped threat, the resolution message that is sent on the current and subsequent cycles to that threat shall contain both the newly selected RAC and the cancellation code for the RAC sent before the reversal.
(13) When a vertical RA is selected, the vertical RAC (VRC) that the own Airborne Collision Avoidance System includes in a resolution message to the threat shall be as follows—
(a) “do not pass above” when the RA is intended to provide separation above the threat; and
(b) “do not pass below” when the RA is intended to provide separation below the threat.
(14) Resolution messages shall be processed in the order in which they are received, and with delay limited to that required to prevent possible concurrent access to stored data and delays due to the processing of previously received resolution messages.
(15) Resolution messages that are being delayed shall be temporarily queued to prevent possible loss of messages.
(16) The processing of a resolution message shall include decoding the message and updating the appropriate data structures with the information extracted from the message.
(17) An RAC or an RAC cancellation received from another Airborne Collision Avoidance System shall be rejected if the encoded sense bits indicate the existence of a parity error or if undefined value is detected in the resolution message.
(18) An RAC or an RAC cancellation received without parity errors and without undefined resolution message values shall be considered valid.
(19) A valid RAC received from another Airborne Collision Avoidance System shall be stored or be used to update the previously stored RAC corresponding to that Airborne Collision Avoidance System.
(20) A valid RAC cancellation shall cause the previously stored RAC to be deleted.
(21) A stored RAC that has not been updated for an interval of six seconds shall be deleted.
(22) A valid RAC or RAC cancellation received from another Airborne Collision Avoidance System shall be used to update the RAC record.
(23) When a bit in a RAC record has not been refreshed for an interval of six seconds by any threat, that bit shall be set to zero.
(24) When an Airborne Collision Avoidance System RA exists, the Airborne Collision Avoidance System shall—
(a) transfer to its Mode S transponder an RA report for transmission to the ground in a Comm-B reply; and
(b) transmit periodic RA broadcasts.
(25) An Airborne Collision Avoidance System shall store SLC commands from Mode S ground stations.
(26) An SLC command received from a Mode S ground station shall, remain effective until replaced by an SLC command from the same ground station as indicated by the site number contained in the IIS subfield of the interrogation.
(27) When an existing stored SLC command from a Mode S ground station is not refreshed within four minutes, or when the SLC command received has the value 15, the stored SLC command for that Mode S ground station shall be set to 0.
35. Provisions for ACAS communication with ground stations
(1) Where an Airborne Collision Avoidance System RA exists, the Airborne Collision Avoidance System shall—
(a) transfer to its Mode S transponder an RA report for transmission to the ground in a Comm-B reply; and
(b) transmit periodic RA broadcasts.
(2) An Airborne Collision Avoidance System shall store SLC commands from Mode S ground stations.
(3) An SLC command received from a Mode S ground station shall remain effective until replaced by an SLC command from the same ground station as indicated by the site number contained in the IIS subfield of the interrogation.
(4) Where an existing stored command from a Mode S ground station is not refreshed within four minutes, or if the SLC command received has the value 15 the stored SLC command for that Mode S ground station shall be set to zero.
36. Provisions for data transfer between ACAS and its Mode S transponder
(1) An Airborne Collision Avoidance System shall transfer data to its Mode S, and shall transfer—
(a) RA information to its Mode S transponder for transmission in an RA report and in a coordination reply;
(b) current sensitivity level to its Mode S transponder for transmission in a sensitivity level report; and
(c) capability information to its Mode S transponder for transmission in a data link capability report.
(2) A Mode S transponder shall transfer data to its Airborne Collision Avoidance System, and the Airborne Collision Avoidance System shall receive from its Mode S transponder—
(a) sensitivity level control commands transmitted by Mode S ground stations;
(b) Airborne Collision Avoidance System broadcast messages transmitted by other Airborne Collision Avoidance System; and
(c) resolution messages transmitted by other Airborne Collision Avoidance System for air-air coordination purposes.
(1) An Airborne Collision Avoidance System shall use the Mode C-only all-call interrogation for surveillance of aircraft equipped with Mode A/C transponders.
(2) A surveillance interrogation shall use a sequence of interrogations with increasing power surveillance being preceded by an S1-pulse to reduce interference and improve Mode A/C target detection.
(3) An Airborne Collision Avoidance System shall monitor 1 090 MHz for Mode S acquisition squitters (DF = 11).
(4) An Airborne Collision Avoidance System shall detect the presence and determine the address of Mode S-equipped aircraft using their Mode S acquisition squitters (DF = 11) or extended squitter (DF = 17).
(5) On first receipt of a 24-bit aircraft address from an aircraft that is determined to be within the reliable surveillance range of ACAS based on reception, reliability and that is within an altitude band 3 050 m (10 000 ft) above and below own aircraft, an Airborne Collision Avoidance System shall transmit a short air-air interrogation (UF = 0) for range acquisition.
(6) A surveillance interrogation shall be—
(a) transmitted at least once every five cycles when the altitude condition in subregulation (5) is satisfied;
(b) transmitted with each cycle, if the range of the detected aircraft is less than 5.6 km (3 NM) or the calculated time to closest approach is less than 60 seconds:
Provided both the detected and own aircraft proceed from their current positions with unaccelerated motion and that the range at closest approach equals 5.6 km (3 NM); and
(c) suspended for a period of five cycles if—
(i) a reply was successfully received,
(ii) own aircraft and intruder aircraft are operating below a pressure-altitude of 5 490 m (18 000 ft), and
(iii) the range of the detected aircraft is greater than 5.6 km (3 NM) and the calculated time to closest approach exceeds 60 seconds:
Provided that both the detected and own aircraft proceed from their current positions with unaccelerated motion and that the range at closest approach equals 5.6 km (3 NM).
(7) An Airborne Collision Avoidance System shall use the short air-air surveillance format (UF = 0) for range acquisition and set AQ = 1 and RL = 0 in an acquisition interrogation.
(8) An Airborne Collision Avoidance System shall use the short air-air surveillance format (UF = 0) with RL = 0 and AQ = 0 for tracking interrogations.
(9) A surveillance replies protocol shall be as described in subregulation 47(1).
(10) An Airborne Collision Avoidance System broadcast shall be made nominally every 8 to 10 seconds at full power from the top antenna.
(11) An installation using directional antennas shall operate in such manner that a complete circular coverage is provided nominally every 8 to 10 seconds.
(12) An Airborne Collision Avoidance System shall, transmit UF = 16 interrogations, with AQ = 0 and RL = 1 when another aircraft reporting RI = 3 or 4 is declared a threat.
(13) The MU field shall contain the resolution message in the subfields specified paragraph 7.2 set out in Schedule 2.
(14) A coordination reply protocol shall be as described in regulation 47(2).
(15) An RA report to Mode S ground station protocol shall be as described in regulation 48(1) and (2).
(16) The RA broadcasts shall, be transmitted at full power from the bottom antenna at jittered, nominally eight seconds intervals for the period that the RA is indicated.
(17) The RA broadcast shall include the MU field as specified in paragraph 7.2.4 set out in Schedule 2.
(18) The RA broadcast shall describe the most recent RA that existed during the preceding eight seconds period.
(19) Installations using directional antennas shall operate such that a complete circular coverage is provided nominally every eight seconds and the same RA sense and strength is broadcast in each direction.
(20) The data link capability report protocols shall be as described in regulation 48(3).
(21) An Airborne Collision Avoidance System shall act upon an SLC command, when TMS has the value 0 and DI is either one or seven in the same interrogation.
(1) The RF characteristics of all Airborne Collision Avoidance System signals shall conform to the standards in paragraphs 1.1.1.1 to 1.1.1.6, 1.1.2.1, 1.1.2.3, 1.1.2.5 and 1.1.2.8 set out in Schedule 1.
(2) The data encoding of all Airborne Collision Avoidance System signals shall conform to the standards in paragraph 1.1.2.3 set out in Schedule 1.
(1) The air-air surveillance and communication formats which are used by Airborne Collision Avoidance System shall, conform to those as set out in Figure 2-1 of the Schedule 2.
(2) The significance of the coding of the downlink request, air-air reply information fields shall be as contained in paragraph 5 set out in Schedule 2.
An Airborne Collision Avoidance System fields and subfields shall be defined in paragraph 6 set out in Schedule 2.
41. ACAS equipment characteristics
(1) An Airborne Collision Avoidance System shall be provided with interfaces, the following input data shall be provided to as the minimum—
(a) aircraft address code;
(b) air-air and ground-air Mode S transmissions received by the Mode S transponder for use by Airborne Collision Avoidance System;
(c) own aircraft’s maximum cruising true airspeed capability;
(d) pressure-altitude; and
(e) radio altitude.
(2) An Airborne Collision Avoidance System shall transmit interrogations and receive replies via two antennas, one mounted on the top of the aircraft and the other on the bottom of the aircraft.
(3) The top-mounted antenna shall be directional and capable of being used for direction finding.
(4) An Airborne Collision Avoidance System polarisation transmission shall be nominally vertical.
(5) The radiation pattern in elevation of an antenna when installed on an aircraft shall, be nominally equivalent to that of a quarter-wave monopole on a ground plane.
42. Antenna selection and pressure altitude source
(1) An Airborne Collision Avoidance System shall be capable of receiving squitters through the top and bottom antennas.
(2) An Airborne Collision Avoidance System interrogation shall not be transmitted simultaneously on both antennas.
(3) The altitude data for an aircraft provided to Airborne Collision Avoidance System shall be obtained from the source that provides the basis for own Mode C or Mode S reports and they shall be provided at the finest quantisation available.
(4) A source providing a resolution finer than 7.62 m (25 ft) shall be used.
(5) Where a source providing a resolution finer than 7.62 m (25 ft) is not available, and the only altitude data available for own aircraft is Gilham encoded, at least two independent sources shall be used and compared continuously in order to detect encoding errors.
(6) Two altitude data sources shall be used and compared in order to detect errors before provision to an Airborne Collision Avoidance System.
(7) When the comparison of two altitude data sources indicates that one of the sources is in error, the provisions of regulation 43(3) shall apply.
(1) An Airborne Collision Avoidance System shall, continuously perform a monitoring function in order to provide a warning, when any of the following conditions are satisfied—
(a) there is no interrogation power limiting due to interference control and the maximum radiated power is reduced to less than that necessary to satisfy the surveillance requirements; or
(b) any other failure in the equipment is detected which results in a reduced capability of providing TAs or RAs; or
(c) data from external sources indispensable for an Airborne Collision Avoidance System operation are not provided, or the data provided are not credible.
(2) An Airborne Collision Avoidance System monitoring function shall, not adversely affect other Airborne Collision Avoidance System functions.
(3) When the Airborne Collision Avoidance System monitoring function detects a failure, Airborne Collision Avoidance System shall—
(a) indicate to the flight crew that an abnormal condition exists;
(b) prevent any further Airborne Collision Avoidance System interrogations; and
(c) cause any Mode S transmission containing own aircraft’s resolution capability to indicate that Airborne Collision Avoidance System is not operating.
44. Requirements for a Mode S transponder used in conjunction with ACAS
(1) The Mode S transponder shall meet the nominal capabilities as defined paragraph 1.1 set out in Schedule 1.
(2) The Mode S transponder used in conjunction with an Airborne Collision Avoidance System shall have the following capabilities—
(a) ability to handle the following formats—
| Format No.
|
Format name
|
| UF = 16
|
Long air-air surveillance interrogation
|
| DF = 16
|
Long air-air surveillance reply;
|
(b) ability to receive long Mode S interrogations (UF = 16) and generate long Mode S replies (DF = 16) at a continuous rate of 16.6 ms (60 per second);
(c) means for delivering the Airborne Collision Avoidance System data content of all accepted interrogations addressed to the Airborne Collision Avoidance System equipment;
(d) antenna diversity;
(e) mutual suppression capability; and
(f) inactive state transponder output power restriction.
(3) When a Mode S transponder transmitter is in the inactive state, the peak pulse power at 1 090 MHz ±3 MHz at the terminals of the Mode S transponder antenna shall not exceed -70 dBm.
45. Data transfer from ACAS to its Mode S transponder
A Mode S transponder shall receive from its Airborne Collision Avoidance System—
(a) RA information for transmission in an RA report and in a coordination reply;
(b) a current sensitivity level for transmission in a sensitivity level report;
(c) capability information for transmission in a data link capability report and for transmission in the RI field of air-air downlink formats DF = 0 and DF = 16; or
(d) an indication that RAs are enabled or inhibited for transmission in the RI field of downlink formats 0 and 16.
46. Data transfer from Mode S transponder to its ACAS
The Mode S transponder shall transfer to its Airborne Collision Avoidance System—
(a) received sensitivity level control commands transmitted by Mode S stations;
(b) received Airborne Collision Avoidance System broadcast messages transmitted by other Airborne Collision Avoidance Systems;
(c) received resolution messages transmitted by other Airborne Collision Avoidance Systems for air-air coordination purposes; or
(d) own aircraft’s Mode A identity data for transmission in an RA broadcast.
47. Communication of ACAS information to other ACAS
(1) The Airborne Collision Avoidance System Mode S transponder shall use the short (DF = 0) or long (DF = 16) surveillance formats to reply to Airborne Collision Avoidance System surveillance interrogations.
(2) The surveillance reply in subregulation (1) shall include—
(a) VS field as specified in paragraph 1.1.2.8.2 set out in Schedule 1;
(b) RI field as specified paragraph 1.1.2.8.2 set out in Schedule 1, and paragraph 5.1.2 set out in Schedule 2; and
(c) SL field as specified in paragraph 8.2.5 set out in Schedule 2.
(3) An Airborne Collision Avoidance System Mode S transponder shall transmit a coordination reply upon receipt of a coordination interrogation from an equipped threat subject to the conditions of subregulation (3).
(4) The coordination reply in subregulation (2) shall use the—
(a) long air-air surveillance reply format, DF = 16;
(b) VS field as specified in paragraph 1.1.2.8.2 set out in Schedule 1;
(c) RI field as specified in paragraph 1.1.2.8.2 set out in Schedule 1, and as specified paragraph 5.1.2 set out in Schedule 2;
(d) SL field as specified in paragraph 8.2.5 set out in Schedule 2; and
(e) MV field as specified in as specified in paragraph 8.2.5.4 set out in Schedule 2.
(5) Coordination replies shall be transmitted even when the minimum reply rate limits of the transponder are exceeded.
(6) An Airborne Collision Avoidance System Mode S transponder shall reply with a coordination reply to a coordination interrogation received from another Airborne Collision Avoidance System:
Provided the transponder can deliver the Airborne Collision Avoidance System data content of the interrogation to its associated Airborne Collision Avoidance System.
48. Communication of ACAS information to ground stations
(1) An Airborne Collision Avoidance System Mode S transponder shall, during an RA and for 18±1 seconds following the end of the RA, indicate that it has an RA report by setting the appropriate DR field code in replies to a Mode S sensor as specified in paragraph 5.1.1. set out in Schedule 2.
(2) The RA report in subregulation (1) shall—
(a) include the MB fields specified in paragraph 6.2.1 set out in Schedule 2; and
(b) describe the most recent RA that existed during the preceding 18±1 s period.
(3) A Mode S transponder shall indicate the presence of its Airborne Collision Avoidance System to a ground station in the Mode S data link capability report.
49. Indications to flight crew
(1) An indication to the flight crew shall distinguish between preventive and corrective RAs.
(2) When Airborne Collision Avoidance System generates an altitude crossing RA, a specific indication shall be given to the flight crew that it is crossing.
50. Performance of ACAS II collision avoidance logic
The performance requirements of the Airborne Collision Avoidance System II collision avoidance logic shall be as specified in paragraph 7 set out in Schedule 2.
51. Conditions under which requirements apply
(1) The following assumed conditions shall apply to the performance requirements specified in regulations 62 and 63—
(a) range and bearing measurements and an altitude report are available for the intruder each cycle provided it is within 14 NM, but not when the range exceeds 14 NM;
(b) the errors in the range and bearing measurements conform to standard range and bearing error models;
(c) the intruder’s altitude reports, which are its Mode C replies, are expressed in 100 ft quanta;
(d) an altitude measurement that has not been quantised and is expressed with a precision of 1 ft or better is available for own aircraft;
(e) errors in the altitude measurements for both aircraft are constant throughout any particular encounter;
(f) the errors in the altitude measurements for both aircraft conform to a standard altimetry error model;
(g) the pilot responses to RAs conform to a standard pilot model;
(h) the aircraft operate in an airspace in which dose encounters, including those in which Airborne Collision Avoidance System generates an RA, conform to a standard encounter model; and
(i) Airborne Collision Avoidance System-equipped aircraft are not limited in their ability to perform the manoeuvres required by their RAs.
(2) The collision avoidance logic performance shall—
(a) not degrade abruptly as the statistical distribution of the altitude errors or the statistical distributions of the various parameters that characterise the standard encounter model or the response of pilot to the advisories are varied; and
(b) when surveillance reports are not available on every cycle or when the quantisation of the altitude measurements for the intruder is varied or the altitude measurements for own aircraft are quantised.
52. Standard range error model
The simulated range measurements errors shall, be taken from a normal distribution with mean 0 ft and standard deviation 50 ft.
53. Standard bearing error model
The simulated bearing measurement errors shall, be taken from a normal distribution with mean 0.0 degrees and standard deviation 10.0 degrees.
54. Standard altimetry error model
A standard altimetry error model shall be defined in paragraph 7 as set out Schedule 2.
A standard pilot model used in the assessment of the performance of a collision avoidance logic shall be that—
(a) any RA is complied with by accelerating to the required rate, if necessary, after an appropriate delay;
(b) when the aircraft’s current rate is the same as its original rate and the original rate complies with the RA, the aircraft continues at its original rate, which is not necessarily constant due to the possibility of acceleration in the original trajectory;
(c) when the aircraft is complying with the RA, its current rate is the same as the original rate and when the original rate changes and consequently becomes inconsistent with the RA, the aircraft continues to comply with the RA;
(d) when an initial RA requires a change in altitude rate, the aircraft responds with an acceleration of 0.25 g after a delay of five seconds from the display of the RA;
(e) when an RA is modified and the original rate complies with the modified RA, the aircraft returns to its original rate, if necessary, with the acceleration specified in paragraph (g) after the delay specified in paragraph (h);
(f) when an RA is modified and the original rate does not comply with the modified RA, the aircraft responds to comply with the RA with the acceleration specified in paragraph (g) after the delay specified in paragraph (h);
(g) the acceleration used when an RA is modified is 0.25 g unless the modified RA is a reversed sense RA or an increased rate RA in which case the acceleration is 0.35 g;
(h) the delay used when an RA is modified is 2.5 seconds unless this results in the acceleration starting earlier than five seconds from the initial RA in which case the acceleration starts five seconds from the initial RA; and
(i) when an RA is cancelled, the aircraft returns to its original rate (if necessary) with an acceleration of 0.25 g after a delay of 2.5 seconds.
(1) In order to calculate the effect of an Airborne Collision Avoidance System on the risk of collision and the compatibility of an Airborne Collision Avoidance System with Air Traffic Management, set of encounters shall be created for each of the following—
(a) the two aircraft address orderings;
(b) the six altitude layers;
(c) 19 encounter classes; and
(d) 9 or 10 VMD bins as specified in paragraph 9.4.3 set out in Schedule 2.
(2) The sets results in subregulation (1) shall be combined using the relative weightings given in regulation 57.
(3) Each set of encounters shall contain at least 500 independent, randomly generated encounters.
(4) The two aircraft trajectories in an encounter shall be constructed with the following randomly selected characteristics—
(a) in the vertical plane—
(i) a VMD from within the appropriate VMD bin,
(ii) a vertical rate for each aircraft at the beginning of the encounter window, 
1, and at the end of the encounter window, 2,
(iii) a vertical acceleration,
(iv) a start time for the vertical acceleration; and
(b) in the horizontal plane—
(i) an HMD,
(ii) an approach angle,
(iii) a speed for each aircraft at closest approach,
(iv) a decision for each aircraft whether or not it turns,
(v) the turn extent; the bank angle; and the turn end time,
(vi) a decision for each aircraft whether its speed changes, and
(vii) the magnitude of the speed change.
(5) Two models shall be used for statistical distribution of HMD, and for calculations for the effect of an Airborne Collision Avoidance System on the risk of collision, HMD shall be constrained to be less than 500 ft, and for compatibility of an Airborne Collision Avoidance System with ATM, HMD shall be selected from a larger range of values.
57. Encounter classes and weights
Encounter classes and weights shall be as contained in paragraph 9.3 set out in Schedule 2.
58. Characteristics of aircraft trajectories in vertical plane
The characteristics of the aircraft trajectories in the vertical plane shall be in accordance with paragraph 9.4 set out in Schedule 2.
59. Characteristics of aircraft trajectories in horizontal plane
The characteristics of the aircraft trajectories in the horizontal plane shall be in accordance with paragraph 9.5 set out in Schedule 2.
The performance requirements set out in regulations 62 and 63 shall, each apply to three distinct situations in which the following conditions concerning an intruder’s Airborne Collision Avoidance System and trajectory shall apply—
(a) where an intruder Airborne Collision Avoidance System involved in each encounter is not equipped, it follows a trajectory identical to that which it follows when own aircraft is not equipped; or
(b) where an intruder is Airborne Collision Avoidance System-equipped but follows a trajectory identical to that in the unequipped encounter—
(i) it follows the identical trajectory regardless of whether or not there is an RA,
(ii) the intruder Airborne Collision Avoidance System generates an RA and transmits an RAC that is received immediately after any RA is first announced to the pilot of own aircraft,
(iii) the sense of the RAC generated by the intruder Airborne Collision Avoidance System and transmitted to own aircraft is opposite to the sense of the first RAC selected and transmitted to the intruder by own aircraft,
(iv) the RAC transmitted by the intruder is received by own aircraft, and
(v) the requirements apply both when own aircraft has the lower aircraft address and when the intruder aircraft has the lower aircraft address; or
(c) where an intruder is equipped with an Airborne Collision Avoidance System having a collision avoidance logic identical to that of own Airborne Collision Avoidance System—
(i) the conditions relating to the performance of own aircraft, Airborne Collision Avoidance System and pilot apply equally to the intruder aircraft, Airborne Collision Avoidance System and pilot,
(ii) RACs transmitted by one aircraft are received by the other, and
(iii) the requirements apply both when own aircraft has the lower aircraft address and when the intruder aircraft has the lower aircraft address.
61. Compatibility between different collision avoidance logic designs
The Authority shall, when considering alternative collision avoidance logic designs verify that—
(a) the performances of the alternative design are acceptable in encounters involving Airborne Collision Avoidance System units that use existing designs; and
(b) the performances of the existing designs are not degraded using the alternative design.
62. Reduction in risk of collision
Subject to regulation 51, a collision avoidance logic shall be that, the expected number of collisions is reduced to the number expected in the absence of an Airborne Collision Avoidance System—
(a) when the intruder is not equipped with Airborne Collision Avoidance System, 0.18;
(b) when the intruder is equipped with Airborne Collision Avoidance System but does not respond, 0.32; and
(c) when the intruder is equipped with Airborne Collision Avoidance System and responds, 0.04.
63. Compatibility with Air Traffic Management (ATM)
(1) The collision avoidance logic shall, be that the proportion of RAs which are a nuisance shall not exceed—
(a) .06 when own aircraft’s vertical rate at the time the RA is first issued is less than 400 ft/min; or
(b) .08 when own aircraft’s vertical rate at the time the RA is first issued exceeds 400 ft/min.
(2) For purposes of subregulation (1), an RA shall, be considered a nuisance, unless during an encounter in the absence of Airborne Collision Avoidance System, the horizontal separation and the vertical separation are simultaneously less than the values specified in accordance with paragraph 10.1 set out in Schedule 2.
64. Compatible sense selection
Subject to regulation 50, the collision avoidance logic shall be that the proportion of encounters in which, following the RA results in an altitude separation at closest approach with the opposite sign to that occurring in the absence of Airborne Collision Avoidance System not exceed the following values—
(a) when an intruder is not Airborne Collision Avoidance System equipped 0.08;
(b) when an intruder is Airborne Collision Avoidance System and is equipped but does not respond 0.08; or
(c) when an intruder is Airborne Collision Avoidance System equipped and responds 0.12.
Subject to regulation 42, the collision avoidance logic shall be the number of RAs resulting in deviations greater than the values indicated and shall not exceed the proportions of the total number of RAs as contained in accordance with paragraph 10.2 set out in Schedule 2.
66. Relative value of conflicting objectives
The collision avoidance logic shall, be to reduce as much as practicable the risk of collision and limit the disruption to ATM.
67. ACAS hybrid surveillance using extended squitter position data
(1) An Airborne Collision Avoidance System equipped to receive extended squitter airborne position messages, for passive surveillance of non-threatening intruders shall, utilise the passive information as set out in regulations 68, 69, 70, and 72(2) to (4).
(2) An Airborne Collision Avoidance System using extended hybrid surveillance mode shall establish a track so that no interrogations are performed when the following conditions are met—
(a) own aircraft position data meets the following minimum level of quality—
(i) own aircraft horizontal position uncertainty (95 per cent) is << 0.1 NM, and
(ii) own aircraft horizontal position integrity shall be such that the probability of an undetected position error, which is greater than 0.6 NM radius, is less than 1 x 10-7′>;
(b) the received signal strength is equal or less than -68 dBm +/-2 dB (extended hybrid surveillance minimum triggering level), or own aircraft is operating on the surface;
(c) the intruder data quality meets the following minimum requirements—
(i) the ADS-B version number 2,
(ii) the reported NIC 6 (<< 0.6 NM),
(iii) the reported NACp 7 (<< 0.1 NM),
(iv) the reported SIL = 3,
(v) the reported SDA = 2 or 3, and
(vi) the barometric altitude is valid; and
(d) the system shall not use ADS-rebroadcast (ADS-R) and TIS-B data to passively acquire an aircraft.
(3) A track maintained under extended hybrid surveillance mode shall transition to a track maintained under active surveillance mode, if the range and altitude of hybrid threat criteria are satisfied.
(4) A track under extended hybrid surveillance mode shall transition to a track under hybrid surveillance mode if—
(a) the signal indicates a high probability to be in proximity, that is, signal > Extended Hybrid Surveillance MTL, except when operating on the airport surface; or
(b) intruder data or own data quality does not meet minimum requirements.
(1) An Airborne Collision Avoidance System shall validate the position of an intruder reported by extended squitter, by determining the relative range and relative bearing as computed from the position and geographical heading of own aircraft and the intruder’s position as reported in the extended squitter.
(2) Subject to subregulation (1), the range, relative bearing and the altitude reported in the squitter shall, be compared to the range, relative bearing and altitude determine by active Airborne Collision Avoidance System interrogations.
(3) The extended squitter data validity shall be determined by the difference between the derived, measured range, and relative bearing, and the squitter and reply altitude shall be computed and used as threat provided in regulation 55.
(4) When any of the validation tests provided under subregulation (3) fail, active surveillance shall be used to track the intruder.
69. Supplementary active interrogations
(1) An intruder’s track shall be updated at least as frequently as required in the absence of an extended squitter data.
(2) When a track is updated using squitter information the time at which an active interrogation would be next required shall be calculated.
(3) An active interrogation shall be made at that time, if a further squitter has not been received before the interrogation is due.
(1) An intruder shall be tracked under active surveillance if it is a near threat, as determined by separate tests done once per second on the range and altitude of the aircraft.
(2) The tests in subregulation (1) shall consider an intruder as a near threat before it becomes a potential threat, and trigger a Traffic Advisory as provided under regulation 51.
71. Revalidation and monitoring
(1) When an aircraft is being tracked using passive surveillance, periodic active interrogations shall be performed to validate and monitor the extended squitter data as set out in regulation 53 and shall be performed for each interrogation.
(2) The rates of revalidation shall be once per minute for a non-threat and once per 10 seconds for a near threat.
(1) When the following condition are met for a track being updated via passive surveillance data the aircraft shall be declared an active track and shall be updated on the active range measurements once per second for as long as the list (a) to (c) below condition are met—
.
(2) A near threat, potential threat or threat shall be tracked using active surveillance.
(3) A track under active surveillance shall transition to passive surveillance if it is not a near threat, potential threat or a threat.
(4) The tests used to determine whether a track is no longer a near threat shall, be similar to those used in regulation 55 but with larger thresholds in order to have hysteresis which prevents the possibility of frequent transitions between active and passive surveillance.
73. ACAS operation with an improved receiver Minimum Triggering Level (MTL)
An Airborne Collision Avoidance System operating with a receiver having a minimum triggering level more sensitive than -74 dBm shall implement the following specified capabilities—
Dual minimum triggering levels—
(a) the Airborne Collision Avoidance System receiver shall, be capable of setting an indication for each squitter reception whether the reply would have been detected by an Airborne Collision Avoidance System operating with a conventional MTL (-74 dBm); or
(b) squitter receptions received at the conventional MTL shall, be passed to the Airborne Collision Avoidance System surveillance function for further processing, and squitter receptions that do not meet this condition shall not be passed to the Airborne Collision Avoidance System surveillance function;
Dual or re-triggerable reply processor the Airborne Collision Avoidance System Mode S reply processing function shall—
(a) use separate reply processors for Mode S reply formats received at or above the conventional MTL and a separate reply processor for Mode S reply formats received below the conventional MTL; or
(b) use a Mode S reply processor that will re-trigger if it detects a Mode S preamble that is 2 to 3 dB stronger than the reply that is currently being processed.
PART V
Mode S Extended Squitter (regs 74-85)
74. Automatic Dependence Surveillance (ADS)-B out requirements
(1) An aircraft, surface vehicles and fixed obstacles supporting a (ADS)-B capability shall incorporate the (ADS)-B message generation function and the (ADS)-B message exchange function (transmit) as depicted in Figure 3-1 and 3-2 set out in Schedule 3.
(2) An (ADS)-B transmission from aircraft shall include position, aircraft identification and type, airborne velocity, and event driven messages including emergency or priority information.
(3) An extended squitter transmitting equipment shall use the latest versions available of formats and protocols.
(4) A Mode S extended squitter transmitting equipment shall be classified according to the unit’s range capability and the set of parameters, that it can transmit consistent with the following definition of general equipment classes and the specific equipment classes defined in accordance with Tables 3-1 set out in Schedule 3—
(a) an extended squitter airborne systems support an interactive capability incorporating, both an extended squitter transmission capability, that is, (ADS)-B OUT with a complementary extended squitter reception capability that is, (ADS)-B IN in support of onboard (ADS)-B applications;
(b) class B extended squitter systems provide a transmission only, that is, (ADS)-B OUT without an extended squitter reception capability, for use on aircraft, surface vehicles, or fixed obstructions; and
(c) class C extended squitter systems have only a reception capability and thus have no transmission requirements.
(5) A class A extended squitter airborne system shall have transmitting and receiving subsystem characteristics of the same class, that is A0, A1, A2, or A3 as provided under subregulation (1) and regulation 63(2).
75. Control of ADS-B out operation
(1) A protection against reception of corrupted data from the source providing the position shall, be satisfied by error detection on the data inputs and the appropriate maintenance of the installation.
(2) When an independent control of the ADS-B OUT function is provided, the operational state of the ADS-B OUT function shall always be indicated to the flight crew.
(1) A ground station supporting a Traffic Information Service-B TIS-B capability shall incorporate the TIS-B message generation function and the TIS-B message exchange function (transmit).
(2) An extended squitter message for TIS-B shall, be transmitted by an extended squitter ground station when connected to an appropriate source of surveillance data.
(3) The maximum transmission rate and effective radiated power of the transmission shall be controlled to avoid unacceptable levels of RF interference to other 1 090 MHz systems under subregulation (2) that is, SSR and Airborne Collision Avoidance System.
77. ADS-B out requirements for surface vehicles
(1) A surface vehicle supporting any versions of extended squitter ADS-B capability shall, transmit extended squitter messages as set out regulation 67(2).
(2) The position source and equipment installed in a surface vehicle to transmit extended squitter version two messages shall, support the following performance characteristics—
(a) the Navigation Accuracy Category Position or the navigation position data shall be greater than or equal to 9, or a 95 per cent accuracy bound on horizontal position less than 30 metres;
(b) the Navigation Accuracy Category Velocity for the navigation velocity data shall, be greater than or equal to two, a velocity error less than three meters per second;
(c) the Navigation Accuracy Category Position and National Accuracy Category Velocity minimum values shall, be met at a minimum availability of 95 per cent; and
(d) the system design assurance parameter shall, be equal to one or more, which defines the probability of a failure resulting in transmission of false or misleading information to be less than or equal to 1 x 10-3′>.
78. Mode S extended squitter receiving system functional requirements
(1) A Mode S extended squitter receiving systems shall perform the message exchange function receive and the report assembler function.
(2) The required functionality and performance characteristics for the Mode S extended squitter receiving system may vary depending on the ADS-B and TIS-B client applications to be supported and the operational use of the system.
(3) A Airborne Mode S extended squitter receivers shall be consistent with the definition of receiving system classes shown in Table 3-3 set out in Schedule 3.
(1) The message exchange function shall, include the 1 090 MHz receiving antenna and the radio, equipment, receiver, demodulator, decoder, data buffer, sub-functions.
(2) An airborne Mode S extended squitter receiving system shall, support the reception and decoding of all extended squitter messages as listed in Table 3-3 of the Schedule 3.
(3) An ground ADS-B extended squitter receiving system shall support the reception and decoding of the extended squitter message types that convey information needed to support the generation of the ADS-B reports of the types required by the client ATM ground applications.
(4) An airborne Mode S extended squitter receiver, demodulation or decoder shall employ the reception techniques and have a receiver minimum trigger threshold level as listed in Table 3-3 set out in Schedule 3, as a function of the airborne receiver class.
(5) A reception technique and MTL for extended squitter ground receiver shall be selected to provide the reception performance, range and update rates, as required by the client Air Traffic Management ground applications.
(6) A Class A1, A2 and A3 airborne receiving systems shall, include the following features to provide improved probability of a Mode S extended squitter reception, in the presence of multiple overlapping Mode A/C fruit or in the presence of an overlapping stronger Mode S fruit, as compared to the performance of the standard reception technique required for Class A0 airborne receiving systems—
(a) improved Mode S extended squitter preamble detection;
(b) enhanced error detection and correction; and
(c) enhanced bit and confidence declaration techniques applied to the airborne receiver classes as shown below—
(i) Class A1 – Performance equivalent to or better than the use of the Centre Amplitude technique,
(ii) Class A2 – Performance equivalent to or better than the use of the Multiple Amplitude Samples baseline technique, where at least eight samples are taken for each Mode S bit position and are used in the decision process, and
(iii) Class A3 – Performance equivalent to or better than the use of the Multiple Amplitude Samples baseline technique, where at least 10 samples are taken for each Mode S bit position and are used in the decision process.
(1) A report assembler function shall include the message decoding, report assembly, and output interface sub-functions.
(2) When an extended squitter message is received, the message shall be decoded and the applicable ADS-B report of the types as provided under regulation 81 shall be generated within 0.5 seconds.
(1) A state vector report shall contain—
(a) the time of applicability;
(b) information about an airborne or vehicle’s current kinematic state such as position and velocity;
(c) the measure of the integrity of the navigation data, based on information received in airborne or ground position;
(d) the airborne velocity; and
(e) the identification and type extended squitter messages.
(2) The time of applicability shall be reported individually for the position related report parameters and the velocity related report parameters, due to separate messages used for the position and velocity.
(3) A State vector report shall include a time of applicability for the estimated position or estimated velocity information, not based on a message with updated position or velocity information, when such estimated position or velocity information is included in the State vector report.
(4) A mode status report shall, contain—
(a) time of applicability and current operational information about the transmitting participant, including airborne or vehicle address;
(b) call sign;
(c) ADS-B version number;
(d) airborne or vehicle length and width information;
(e) state vector quality information; and
(f) other information based on information received in operational status, airborne identification and type, airborne velocity and airborne status extended squitter messages.
(5) A report assembler function shall update the report time of applicability when a mode status report is generated.
(6) A parameter which do not have a valid data available shall, either be indicated as invalid or omitted from the mode status report.
(7) An air referenced velocity reports shall be generated when the air referenced velocity information is received in airborne velocity extended squitter messages.
(8) An air referenced velocity report shall, contain time of applicability, airspeed and heading information.
(9) Certain classes of extended squitter receiving systems, as defined in regulation 83 are required to generate air referenced velocity reports.
(10) When an individual mode status report is generated, the report assembly function shall update the report time of applicability.
(11) An RA report shall contain time of applicability and the contents of an active Airborne Collision Avoidance System Resolution Advisory as received in a Type=28 and Subtype=2 extended squitter message.
(1) When a TIS-B message is received by airborne receiving systems, the information shall be reported to client applications.
(2) When an individual TIS-B report is generated, the report assembly function shall update the report time of applicability to the current time.
(3) A received information elements, except the position, shall be reported directly, including all reserved fields for the TIS-B fine format messages, and the entire message content of any received TIS-B management message.
(4) An information content reported shall, be the same as the information content received.
(5) When a TIS-B position message is received, it is compared with tracks to determine whether it can be decoded into target position, correlated to an existing track.
(6) When the message in subregulation (5) is decoded into target position a report shall be generated within 0.5 seconds.
(7) The report under subregulation (6) shall contain—
(a) the received position information with a time of applicability;
(b) the most recently received velocity measurement with a time of applicability;
(c) the estimated position and velocity applicable to a common time of applicability, airborne or vehicle address; and
(d) all other information in the received message.
(8) The estimated values shall be based on the received position information and the track history of the target.
(9) When a TIS-B velocity message is received, if it is correlated to a complete track—
(a) a report shall be generated, within 0.5 seconds of the message reception; and
(b) the estimated values shall be based on the received ground reference velocity information and track history of the target.
(10) The report in subregulation (9), shall—
(a) contain the received velocity information with a time of applicability;
(b) the estimated position and velocity applicable to a common time of applicability; and
(c) airborne or vehicle address, and all other information in the received message.
(11) The whole message content of any received TIS-B management message shall, be reported directly to the client applications.
(12) The contents of a received TIS-B management message shall, be reported bit-for-bit to the client applications.
(13) The information content reported shall, be the same as the information content received.
83. Report time of applicability
(1) The receiving system shall use a local source of reference time as the basis for reporting the time of applicability, as defined for each specific ADS-B and TIS-B report type.
(2) A receiving system intended to generate ADS-B or TIS-B reports based on the reception of surface position messages, airborne position messages, or TIS-B messages shall use General Navigation Satellite System UTC measured time for the purpose of generating the report time applicability for the following cases of received messages—
(a) version zero (0) ADS-B messages, as defined in paragraph 1.1.2.8.6.2 set out Schedule 1, when the navigation uncertainty category is 8 or 9; or
(b) version zero (0) ADS-B messages, as defined in paragraphs 1.1.2.8.6.2 and 1.1.2 8.7 set out Schedule 1 when the navigation integrity category is 10 or 11.
(3) A UTC measured time data shall have a minimum range of 300 seconds and a resolution of 0.0078125 (1/128) seconds.
(4) For a receiving system not intended to generate ADS-B or TIS-B reports, based on reception of ADS-B or TIS-B messages meeting the NUC or NIC criteria as provided under subregulation (2), a non-precision time source shall be allowed.
(5) Where there is no appropriate precision time source available, the receiving system shall establish an appropriate internal clock or counter having a maximum clock cycle or count time of 20 milliseconds.
(6) A established cycle or clock count shall, have a minimum range of 300 seconds and a resolution of 0.0078125 (1/128) seconds.
(1) The report assembler function associated with Type I Mode S extended squitter receiving systems, as defined in regulation 65, shall support that subset of ADS-B and TIS-B reports and report parameters, that are required by the specific client applications being served by that receiving system.
(2) The report assembler function associated with Type II receiving systems, as defined in regulation 65, shall generate ADS-B and TIS-B reports according to the class of the receiving system as provided under Table 3-4 set out in Schedule 3, when the prerequisite ADS-B or TIS-B messages are being received.
(3) The report assembler function associated with Mode S extended squitter ground receiving systems, as defined in regulation 65, shall support that subset of ADS-B reports and report parameters that are required by the specific client applications being served by that receiving system.
(1) The Mode S extended squitter receiving system shall provide interoperability with both version zero and version one extended squitter ADS-B message formats.
(2) The Mode S extended squitter receiving system shall upon acquiring a new ADS-B target, initially apply the decoding provisions applicable to version 0 ADS-B messages until or unless an operational status message is received indicating version one message format is in use.
(3) The Mode S extended squitter receiving system shall—
(a) decode the version number information conveyed in the operational status message; and
(b) apply the corresponding decoding rules, version 0 or version 1, for the decoding of the subsequent extended squitter ADS-B messages from that specific airborne or vehicle.
(4) The Mode S extended squitter receiving system shall ignore the contents of any message subfield defined as reserved.
PART VI
Multilateration (MLAT) Systems (regs 86-88)
(1) The Radio Frequency characteristics, structure and data contents of signals used in 1 090 MHz MLAT systems shall conform to the provisions of Schedule 1.
(2) An MLAT system used for air traffic surveillance shall be capable of determining aircraft position and identity.
(3) Where an MLAT system is equipped to decode additional position information contained in transmissions, it shall report such information separately from the aircraft position calculated based on Time Difference of Arrivals.
87. Protection of radio frequency environment
(1) The effective radiated power of active interrogators shall be reduced to the lowest value consistent with the operationally required range of each individual interrogator site.
(2) An active MLAT system shall not use active interrogations to obtain information that can be obtained by passive reception within each required update period.
(3) An active MLAT system consisting of a set of transmitters shall be considered as a single Mode S interrogator.
(4) The set of transmitters used by all active MLAT systems in any part of the airspace shall, not cause any transponder to be impacted such that its occupancy, because of the aggregate of all MLAT 1 030 MHz interrogations, is greater than two per cent at any time.
(5) An active MLAT systems shall not use Mode S all-call interrogations.
The performance characteristics of the MLAT system used for air traffic surveillance shall be that the intended operational service can be satisfactorily supported.
PART VII
Technical Requirements for Airborne Surveillance Applications (regs 89-90)
(1) An Airborne Collision Avoidance System shall support a function to identify unambiguously each reference aircraft relevant to the application.
(2) An Airborne Collision Avoidance System shall support a function to monitor the movements and behavior of each reference aircraft relevant to the application.
(3) An Airborne Collision Avoidance System shall support a computational function to predict the future position of a reference aircraft beyond simple extrapolation.
(1) An Airborne Collision Avoidance System shall display only one track for each distinct aircraft on a given display.
(2) Where a track generated by ADS-B/TIS-B IN and a track generated by an Airborne Collision Avoidance System have been determined to belong to the same aircraft, the track generated by ADS-B/TIS-B IN shall be displayed.
(3) The display of the tracks shall, comply with the requirements of Airborne Collision Avoidance System traffic display.
PART VIII
General Provisions (regs 91-98)
91. Application for exemptions
(1) An Air Navigation Service Provider who wishes to be exempted from any requirement under these Regulations may apply to the Authority in writing.
(2) The application shall specify the time when the Air Navigation Service Provider is expected by the Authority to fully comply.
92. Drug and alcohol testing and reporting
(1) A person who performs any function determined by these Regulations directly or by contract, under the provisions of these Regulations may be tested for drug or alcohol usage.
(2) A person who refuses to submit to a test to indicate—
(a) the percentage by weight of alcohol in the blood; or
(b) the presence of narcotic drugs, marijuana, or depressant or stimulant drugs or substances in the body, when requested by a law enforcement officer or the Authority, or refuses to furnish or to authorise the release of the test results requested by the Authority shall—
(i) be denied any licence, certificate, rating, qualification, or authorisation issued under these Regulations for a period of up to one year from the date of that refusal, or
(ii) have his or her licence, certificate, rating, qualification, or authorisation issued under these Regulations suspended or revoked.
(3) Any person who is convicted for the violation of any local or national statute relating to the growing, processing, manufacture, sale, disposition, possession, transportation, or importation of narcotic drugs, marijuana, or depressant or stimulant drugs or substances, shall—
(a) be denied any license, certificate, rating, qualification, or authorisation issued under these Regulations for a period of up to one year after the date of conviction; or
(b) have his or her licence, certificate, rating, qualification, or authorisation issued under these Regulations suspended or revoked.
(1) An Air Navigation Service Provider holder of a certificate issued under these Regulations, shall apply to the Authority for—
(a) replacement of the certificate if lost or destroyed;
(b) change of name on the certificate; or
(c) an endorsement on the certificate.
(2) For purpose of subregulation (1), the holder of a certificate shall submit to the Authority—
(a) the original certificate, or a copy thereof in case of loss; and
(b) a court order, or other legal document verifying the name change.
(3) The Authority shall return to the holder of a certificate, with the appropriate changes applied for, if any, the originals specified under subregulation (2) and, where necessary, retain copies thereof.
(1) A holder of a CNSP certificate issued under these Regulations shall notify the Authority of the change in the physical and mailing address within 14 days of such change.
(2) A holder of a CNSP certificate who does not notify the Authority of the change in the physical and mailing address within the time frame specified in subregulation (1), shall not exercise the privileges of the certificate.
A person shall apply to the Authority in Form A set out in Schedule 4 for replacement of documents issued under these Regulations if such documents are lost or destroyed.
96. Use and retention of documents and records
(1) A person shall not—
(a) use any certificate or exemption issued or required by or under these Regulations which has been forged, altered, cancelled, or suspended, or to which he is not entitled;
(b) forge or alter any certificate or exemption issued or required by or under these Regulations;
(c) lend any certificate or exemption issued or required by or under these Regulations to any other person;
(d) make any false representation for the purpose of procuring for himself or any other person the grant, issue, renewal or variation of any such certificate or exemption; or
(e) mutilate, alter, render illegible or destroy any records, or any entry made therein, required by or under these Regulations to be maintained, or knowingly make, or procure or assist in the making of, any false entry in any such record, or wilfully omit to make a material entry in such record.
(2) Any record required to be maintained by or under these Regulations shall be recorded in a permanent and indelible material.
(3) A person shall not issue any certificate or exemption under these Regulations unless he or she is authorised by the Authority.
(4) A person shall not issue any certificate referred to in subregulation (3), unless he or she has satisfied himself or herself that all statements in the certificate are correct, and that the applicant is qualified to hold that certificate.
(1) Any person who knows of a violation of these Regulations, rules, or orders issued there under, shall report it to the Authority.
(2) For purposes of subregulation (1), the Authority shall determine the nature and type of investigation or enforcement action that need to be taken.
98. Failure to comply with direction
Any person who fails to comply with any direction given to him or her by the Authority or by any authorised person under any provision of these Regulations shall be deemed for the purposes of these Regulations to have contravened that provision.
PART IX
Offences and Penalties (reg 99)
(1) A person who contravenes any provision of these Regulations, orders, notices or proclamations made there under is liable to a fine or imprisonment or both, and in the case of a continuing contravention, each day of the contravention shall constitute a separate offence.
(2) Any person who contravenes any provision of these Regulations is to be liable to a fine not exceeding P 100 000 or to imprisonment for a term not more than six months, or to both.
(3) If it is proved that an act or omission of any person, which would otherwise have been a contravention by that person of a provision of these Regulations, orders, notices or proclamations made under the Regulations was due to any cause not avoidable by the exercise of reasonable care by that person, the act or omission shall be deemed not to be a contravention by that person of that provision.
(regs 14, 17-22, 24, 27, 38, 44, 47, 83 and 86)
(regs 28, 30, 32, 37, 39, 40, 47, 48, 50, 54, 56-59, 63 and 65)
SCHEDULE 3
AUTOMATIC DEPENDENT SURVEILLANCE – BROADCAST
(regs 74, 78, 79 and 84)
FORM A
(reg 95)
