**Executive Summary**
This document outlines the Civil Aviation Requirements in India regarding the installation and operation of Mode 'A'/'C' and Mode 'S' transponders in aircraft. It specifies equipment requirements for various aircraft types and operational scenarios, aiming to enhance air traffic control and safety. The document is effective immediately from 8th Feb, 1994. Aircraft operators equipped with Mode 'S' transponders must apply to the Director General of Civil Aviation for a Mode 'S' address.
**Key Points / Main Content**
* **Transponder Requirements:**
* All aeroplanes should be equipped with a pressure-altitude reporting transponder.
* From 1st January, 1999, all aeroplanes shall be equipped with a pressure altitude reporting transponder.
* Aircraft must have transponders based on their certified take-off mass, passenger seating configuration, and type of operation (commercial or general aviation).
* Certain aeroplanes and helicopters must be equipped with Mode 'A'/'C' or Mode 'S' transponders by specific dates for both commercial air transport and general aviation operations.
* **Technical Specifications and Definitions:**
* Defines primary and secondary surveillance radars, surveillance radar, and associated radio frequencies (interrogation and reply).
* Defines traffic information service, traffic alert & collision avoidance system, airborne collision avoidance system, aircraft address, automatic dependent surveillance and collision avoidance logic.
* Includes definitions of concepts like Human Factors, Multilateration, Modes of transponders, and types of air transport operation.
* **Aircraft Address Assignment:**
* Aircraft operators must inform the airframe manufacturer for address assignment upon delivery.
* Aircraft changing its State of Registry shall assign a new address.
* Outlines the process for obtaining a Mode 'S' address from DGCA, including required documentation (Aircraft Type and Registration Number, Serial Number of the aircraft, and Name and address of the Operator).
* Director General of Civil Aviation will maintain a register of all aircraft allotted with Mode 'S' address.
* **Temporary Aircraft Address Administration:**
* Temporary addresses can be assigned by ICAO in exceptional circumstances.
* Details the information required for requesting a temporary address from ICAO.
* Outlines the responsibilities of the aircraft operator in relation to temporary and permanent addresses, including informing DGCA and ICAO.
* **Operational & Maintenance Requirements:**
* The aeroplane flight manual should be amended to include appropriate procedure for the use of transponders.
* The operator shall lay down its procedure to ensure that the transponder is kept 'ON' throughout the operations.
* Specifies transponder types that meet the required specifications.
* Transponders must be installed and maintained in accordance with approved standards.
* Engineers inspecting/certifying the transponders should hold appropriate type rated licence in category "B2" and should be adequately trained on this equipment.
**Impact Analysis**
**Stakeholder: Aircraft Operators**
* **Impact:** Must ensure their aircraft are equipped with the appropriate transponders based on aircraft type, operation, and passenger capacity. Required to apply for and manage aircraft addresses.
* **Action Required:** Upgrade or install transponders as required. Apply to DGCA for Mode 'S' addresses. Update aircraft flight manuals and ensure adherence to operational procedures.
**Stakeholder: Airframe Manufacturers**
* **Impact:** Need to install correctly assigned addresses supplied by DGCA.
* **Action Required:** Coordinate with aircraft operators and DGCA regarding aircraft address assignments.
**Stakeholder: Maintenance Engineers/Organizations**
* **Impact:** Responsible for the proper installation, maintenance, and certification of transponders.
* **Action Required:** Ensure qualified personnel and adherence to maintenance standards.
**Stakeholder: Director General of Civil Aviation (DGCA)**
* **Impact:** Responsible for regulating and enforcing the requirements, maintaining a register of allocated Mode 'S' addresses.
* **Action Required:** Review and process applications for Mode 'S' addresses and enforce compliance with the regulations.
**Stakeholder: ICAO**
* **Impact:** Responsible for assigning the temporary aircraft addresses.
* **Action Required:** To provide timely information to DGCA of the issuance of the temporary address.
Key Entities Referenced
Aircraft Rules, 1937: Governing regulations for aircraft operations, stipulating requirements for aircraft equipment and instruments.
ICAO Annex 6: Standards and recommended practices related to operation of aircraft. The document mentions Part II regarding general aviation aeroplanes.
Director General of Civil Aviation (DGCA): The civil aviation authority responsible for regulating airworthiness and aircraft equipment in India, including the installation and use of transponders.
Mode 'A' / 'C' and Mode 'S' Transponders: Electronic devices used in aircraft for air traffic control, providing altitude reporting and data link capabilities.
GOVERNMENT OF INDIA
OFFICE OF DIRECTOR GENERAL OF CIVIL AVIATION
TECHNICAL CENTRE, OPP SAFDARJANG AIRPORT, NEW DELHI
CIVIL AVIATION REQUIREMENTS
SECTION 2 - AIRWORTHINESS
SERIES 'R', PART IV
DATED 8TH FEB, 1994 EFFECTIVE: FORTHWITH
SUBJECT: INSTALLATION OF MODE 'A' / 'C' AND MODE βSβ TRANSPONDERS.
1. INTRODUCTION :
1.1 As part of modernisation of air traffic control facilities, Secondary Surveillance
Radars are being provided to cover the major air routes in the country and
also to provide the Minimum Safe Altitude Warning (MSAW) System. To
derive full benefit of these facilities it is necessary that the aeroplanes
operating in Indian airspace are fitted with the altitude reporting
transponders.
1.2 ICAO Annex 6 Part II relating to operation of general aviation aeroplanes also
requires that:
βall aeroplanes shall be equipped with a pressure-altitude reporting
transponder which operates in accordance with the relevant provision of
Annex10,Vol.IV.β
Further, the Asia Pacific Air Navigation Planning and Implementation
Regional Group (APANPIRG), have also recommended in their report of
eighth meeting held from 23rd to 29th September, 1997 that:
-
βfrom 1st January, 1999 all aeroplanes shall be equipped with a pressure
altitude reporting transponder.
1.3 Mode βAβ / βCβ transponder provides traffic advisory in an aircraft fitted with
ACAS-I/ TCAS-I and both traffic advisory and resolution advisory in an
aircraft fitted with ACAS-II/ TCAS-II. Mode βSβ Transponder is a source of
reliable air space surveillance. It enhances the operation of Air Traffic Control
Radar Beacon System (ATCRBS) by adding a Data Link feature and
interrogation capability over and above Mode βAβ / βCβ transponder operation
which only determines the aircraft altitude. Mode βSβ transponder also
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provides traffic advisory in an aircraft fitted with ACAS-I/ TCAS-I and both
traffic advisory and resolution advisory in an aircraft fitted with ACAS-II/
TCAS-II.
1.4 The Data Link facility allows Mode βSβ transponder to perform additional Air
Traffic Control and Air Separation Assurance (ASA) functions. Due to
discrete addressing feature of Mode βSβ transponder, the capability of
interrogators is enhanced to handle more number of aircraft. Installation of
Mode βAβ / βCβ and Mode βSβ transponders enhances the safety of aircraft
operations and gives relief to pilots and ATCOs by reducing voice
communication.
1.5 Sub Rule 3 of Rule 9 and Rule 57 of the Aircraft Rules, 1937, stipulate that
every aircraft shall be fitted and equipped with instruments and equipments
including radio apparatus and special equipment as may be specified
according to the use and circumstances under which the flight is to be
conducted. This part of the CAR lays down the requirements for installation
of Mode βAβ / βCβ and Mode βSβ transponders and describes the procedure for
allotment of Mode 'S' address. This CAR is issued under the provisions of
Rule 57 and Rule 133A of the Aircraft Rules, 1937.
2. DEFINITIONS:
2.1 Primary Radar: Primary Radar transmits a beam of radio frequency energy
and subsequently receives the minute proportion of this energy which has
been echoed back to it by the target. This reflected signal is picked up and
processed to provide a display which shows the location of the target.
2.2 Secondary Radar: This radar transmits a characteristic group of pulses
recognizable to the transponder in the target aircraft which then responds
after a pre-determined precise interval with a coded train of pulses which
identifies and/or provides information about the aircraft.
2.3 Surveillance radar. Radar equipment used to determine the position of an
aircraft in range and azimuth.
2.3.1 INTERROGATION AND CONTROL (INTERROGATION SIDE-LOBE
SUPPRESSION) RADIO FREQUENCIES (GROUND-TO-AIR)
2.3.1.1 The carrier frequency of the interrogation and control
transmissions shall be 1030 MHz.
2.3.1.2 The frequency tolerance shall be plus or minus 0.2 MHz.
2.3.1.3 The carrier frequencies of the control transmission and of each
of the interrogation pulse transmissions shall not differ from
each other by more than 0.2 MHz.
2.3.2 REPLY CARRIER FREQUENCY (AIR-TO-GROUND)
2.3.2.1 The carrier frequency of the reply transmission shall be 1090
MHz.
2.3.2.2 The frequency tolerance shall be plus or minus 3 MHz.
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2.4 Secondary Surveillance Radar (SSR): The SSR as per ICAO is required to
provide an identification capability within the worldβs air traffic control systems.
It was derived from Identification of Friend or Foe (IFF) system with which it
co-exists and inter-operates the system comprising of interrogative radar on
the ground and transponder beacons carried on aircraft.
2.5 Traffic information service β broadcast (TIS-B) IN. A surveillance function
that receives and processes surveillance data from TIS-B OUT data sources.
2.6 Traffic information service β broadcast (TIS-B) OUT. 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.
2.7 Traffic Alert & Collision Avoidance System (TCAS): It is an independent
aircraft equipment designed to detect potential conflicting aircraft that are
equipped with Secondary Surveillance Radar (SSR) Transponders.
2.8 Airborne Collision Avoidance System (ACAS): An aeroplane 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.
Note - SSR transponders referred to above are those operating in Mode C or
Mode S.
2.9 Aircraft address. A unique combination of twenty-four bits available for
assignment to an aircraft for the purpose of air-ground communications,
navigation and surveillance.
Note- SSR Mode S transponders transmit extended squitters to support the
broadcast of aircraft-derived position for surveillance purposes. The
broadcast of this type of information is a form of automatic dependent
surveillance (ADS) known as ADS-broadcast (ADS-B).
2.10 Automatic dependent surveillance-broadcast (ADS-B) OUT. 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.
2.11 Automatic dependent surveillance-broadcast (ADS-B) IN. A function that
receives surveillance data from ADS-B OUT data sources.
2.12 Collision avoidance logic. The sub-system or part of ACAS that analyses
data relating to an intruder and own aircraft, decides whether or not advisories
are appropriate and, if so, generates the advisories. It includes the following
functions: range and altitude tracking, threat detection and RA generation. It
excludes surveillance.
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2.13 Human Factors principles. 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.
2.14 Multilateration (MLAT) System. 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.
2.15 Time Difference of Arrival (TDOA). The difference in relative time that a
transponder signal from the same aircraft (or ground vehicle) is received at
different receivers.
2.16 Mode βAβ β An interrogation that elicits reply from transponder for identity and
surveillance.
2.17 Mode βCβ β An iterrogation that elicits reply from transponder for automatic
pressure altitude transmission and surveillance.
The above modes defined in 2.16, 2.17 and 2.18 are used during interrogation
for air traffic services.
2.18 Mode βAβ / βCβ transponderβ Airborne equipment that generates specified
responses to Mode βAβ, Mode βCβ and intermode interrogations but does not
reply to Mode βSβ interrogations.
2.19 Mode `S': It is a mode select - A transponder format to allow discrete
interrogation and data link capability. The Mode `S' ground equipment
operates on the same frequency as SSR and comprises an interrogator and a
receiver. Monopulse techniques are invariably used. In addition to Mode `Sβ
function, the ground station will also radiate standard SSR mode and will
therefore be capable of operating in conjunction with aircraft carrying
standard SSR equipment. In the same way, Mode `S' transponder will be
compatible with SSR ground stations.
2.20 Mode `Sβ transponder: It provides the communication capabilities (data
link) required for ACAS/ TCAS as well as for Air Traffic Control Radar
Beacon System (ATCRBS) transponder function (Mode βAβ and Mode βCβ
operation).
2.21 Commercial Air Transport Operation: An aircraft operation involving the
transport of passengers, cargo or mail for remuneration or hire.
2.22 General Aviation Operation: An aircraft operation other than a commercial
air transport operation or an aerial work operation.
3. REQUIREMENTS
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3.1 Unless otherwise authorised by DGCA, no person shall operate in the Indian
airspace, an aeroplane having maximum certified take off mass of 5700 kg
and above or a maximum cruising true airspeed capability in excess of 463 km/h
(250kt) and having maximum certified passenger seating configuration
(excluding any pilot seats) of more than 30 seats or maximum payload
capacity of more than 3 tones without antenna diversity as prescribed in 3.1.1
3.1.1 Transponder antenna system and diversity operation. Mode S
transponders equipped for diversity operation shall have two RF ports
for operation with two antennas, one antenna on the top and the other
on the bottom of the aircraftβs fuselage. The received signal from one of
the antennas shall be selected for acceptance and the reply shall be
transmitted from the selected antenna only.
3.2 Unless otherwise authorised by DGCA, no person shall operate for
commercial air transport operation in the Indian airspace, from 1st January,
2001,
(a) an aeroplane having a maximum certified passenger seating configuration
of 20 to 30 or a maximum certificated take off mass in excess of 5700kg, if
such aeroplane is not equipped with Mode 'S' transponder.
(b) an aeroplane having a maximum certified passenger seating configuration
of 10 to 19 and a maximum certificated take off mass less than 5700kg, if
such aeroplane is not equipped with Mode βAβ / βCβ transponder.
(c) a twin jet engined aeroplane having a maximum certified passenger
seating configuration of less than 10 and a maximum certificated take off
mass less than 5700kg, if such aeroplane is not equipped with Mode βAβ /
βCβ transponder
(d) a helicopter if it is not equipped with Mode βAβ / βCβ transponder.
3.3 Unless otherwise authorised by DGCA, no person shall acquire for the
purpose of commercial air transport operation in the Indian airspace, from
1st January, 2000:
(a) an aeroplane having a maximum certified passenger seating configuration
of 20 to 30 or a maximum certificated take off mass in excess of 5700kg,
if such aeroplane is not equipped with Mode 'S' transponder.
(b) an aeroplane having a maximum certified passenger seating configuration
of 10 to 19 and a maximum certificated take off mass less than 5700kg, if
such aeroplane is not equipped with Mode βAβ / βCβ transponder .
(c) a twin jet engined aeroplane having a maximum certified passenger
seating configuration of less than 10 and a maximum certificated take off
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mass less than 5700kg, if such aeroplane is not equipped with Mode
βAβ/βCβ transponder.
(d) a helicopter if it is not equipped with Mode βAβ / βCβ transponder.
3.4 Unless otherwise authorised by DGCA, no person shall operate for general
aviation operation in the Indian controlled airspace or on promulgated ATS
routes, from 1st January, 2003, an aeroplane or helicopter, if it is not
equipped with Mode βAβ / βCβ transponder.
4. ASSIGNMENT OF AIRCRAFT ADDRESSES
4.1 For an aircraft delivery, the aircraft operator is expected to inform the airframe
manufacturer of an address assignment. The airframe manufacturer or other
organization responsible for a delivery flight is expected to ensure installation
of a correctly assigned address supplied by DGCA. Exceptionally, a
temporary address may be supplied under the arrangements detailed in
paragraph 6.
4.2 When an aircraft changes its State of Registry, the new registering State shall
assign the aircraft a new address from its own allocation address block, and
the old aircraft address shall be returned to DGCA.
4.3 the address shall serve only a technical role for addressing and identification
of aircraft and shall not be used to convey any specific information; and
5. PROCEDURE FOR ALLOTMENT OF MODE 'S' ADDRESS
5.1 Aircraft fitted with Mode βSβ transponder will be provided with Mode βSβ
address by DGCA which consists of a total of 24 bits. The first six bits indicate
the country code and the remaining 18 bits give the Mode βSβ address. The
code allotment shall be as given below: -
1 0 0 0 0 0 - - - - - - - - - - - - - - - - - -
<-- (6 bits) ----> <----- (18 bits) ---------(cid:198)
Country Code Mode S Address
for India
5.2 Whenever an aircraft is equipped with Mode βSβ transponder, the aircraft
operator/owner shall apply to Director General of Civil Aviation, (Attn.:
Director of Airworthiness) Technical Center, Opp. Safdarjung Airport, New
Delhi -110003, for allotment of specific Mode βSβ address giving the following
information:
(i) Aircraft Type and Registration Number.
(ii) Serial Number of the aircraft.
(iii)Name and address of the Operator.
After the above information is received, the specific code shall be allotted by
Director General of Civil Aviation.
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5.3 Register of aircraft allotted with Mode βSβ address.
The Director General of Civil Aviation will maintain a register of all aircraft
allotted with Mode βSβ address. This register will be open to inspection by any
person desirous of doing so.
5.4 All Indian registered aircraft fitted with Mode βSβ transponder shall be issued
with Mode βSβ address by DGCA. Mode βSβ address issued by any other
foreign regulatory authority shall stand cancelled after issue of Indian
registration.
6. ADMINISTRATION OF THE TEMPORARY AIRCRAFT ADDRESS
ASSIGNMENTS
6.1 Temporary addresses shall be assigned by ICAO to aircraft in exceptional
circumstances, such as when operators have been unable to obtain an
address from DGCA in a timely manner.
6.2 When requesting a temporary address, the aircraft operator shall supply to
ICAO: aircraft identification, type and make of aircraft, name and address of
the operator, and an explanation of the reason for the request.
6.2.1 Upon issuance of the temporary address to the aircraft operators,
ICAO shall inform DGCA of the issuance of the temporary address,
reason and duration.
6.3 The aircraft operator shall:
(a) inform DGCA of the temporary assignment and reiterate the request for a
permanent address; and
(b) inform the airframe manufacturer.
6.4 When the permanent aircraft address is obtained from DGCA, the operator
shall:
(a) inform ICAO without delay;
(b) relinquish his/her temporary address; and
(c) arrange for encoding of the valid unique address within 180 calendar days.
6.5 If a permanent address is not obtained within one year, the aircraft operator
shall reapply for a new temporary aircraft address. Under no circumstances
shall a temporary aircraft address be used by the aircraft operator for over
one year.
7. OPERATIONAL REQUIREMENTS:
7.1 Prior to commencing operation of the aircraft fitted with Mode βAβ / βCβ or Mode
βSβ transponder as required by para 3 above, the aeroplane flight manual shall
be amended to include:
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(i) appropriate procedure for the use of transponders;
(ii) necessary amendment to the checklist.
7.2 The operator shall lay down its procedure to ensure that the transponder is
kept βONβ throughout the operations.
7.3 The transponder should be operated in accordance with the relevent provision
of ICAO Annex 10 Volume IV.
8. MAINTENANCE AND CERTIFICATION OF TRANSPONDERS
8.1 The transponder shall be of approved type and meet the specifications given
in TSOβC74 C for Mode βAβ/βCβ transponder and TSO-C112 for Mode βSβ
transponder or any other specifications acceptable to DGCA.
8.2 The transponder shall be installed in an approved manner by an approved
organisation / manufacturer.
8.3 The transponder shall be maintained in serviceable condition. For release of
aircraft under MEL due to defect in the transponder system, an entry shall be
made in the maintenance record that includes the date and time of invoking
the MEL and proper placarding in the cockpit.
8.4 Engineers inspecting/certifying the transponders should hold appropriate type
rated licence in category βB2" and should be adequately trained on this
equipment.
(Charan Dass)
Joint Director General of Civil Aviation
for Director General of Civil Aviation
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