AAI manages 125 airports in India and provides air navigation services over 2.8 million square nautical miles of airspace. It is responsible for communication, navigation, and surveillance facilities at airports. The key CNS facilities include VHF systems for air-to-ground communication, satellite networks, voice switching systems, navigation aids like VOR and ILS to determine aircraft position, and surveillance systems like radar. AAI aims to ensure safe and efficient air navigation through these CNS facilities.

2. Objectives
Aim
Civil Aviation Setup in India
Introduction to Airports Authority of India (AAI)
Meaning of CNS
Communication Facilities
Navigation Facilities
Surveillance Facilities
Conclusion

3. Aim
• To get acquainted with Communication, Navigation and
Surveillance aids in airports authority of India.

5. Introduction
to
Airports Authority of India (AAI)

7. Introduction to AAI
 Airports Authority of India (AAI) was constituted by an Act
of Parliament and came into being on 1st April 1995 by
merging erstwhile National Airports Authority and
International Airports Authority of India. The merger
brought into existence a single Organization entrusted with
the responsibility of creating, upgrading, maintaining and
managing civil aviation infrastructure both on the ground
and air space in the country.

8.  AAI manages 125 airports, which include 18 International
Airports, 7 Custom Airports, 78 Domestic Airports and 26
Civil Enclaves at Defence airfields.
 AAI provides air navigation services over 2.8 million square
nautical miles of air space. (1Nmile=1.852Km).
 During the year 2013-14, AAI handled aircraft movement of
1536.60 Thousand [International 335.95 & Domestic
1200.65], Passengers handled 168.91 Million [International
46.62 & Domestic 122.29] and the cargo handled 2279.14
thousand [International 1443.04 & Domestic 836.10].

9. Functions of AAI
The functions of AAI are as follows:
 Design, Development, Operation and Maintenance of international and
domestic airports and civil enclaves.
 Control and Management of the Indian airspace extending beyond the
territorial limits of the country, as accepted by ICAO*.
 Construction, Modification and Management of passenger terminals.
 Development and Management of cargo terminals at international and
domestic airports.
 Provision of passenger facilities and information system at the passenger
terminals at airports.
 Expansion and strengthening of operation area, viz. Runways, Aprons,
Taxiway etc.
 Provision of visual aids.
 Provision of Communication and Navigation aids, viz. ILS, DVOR, DME,
Radar etc.
*ICAO: International Civil Aviation Organization

10. Meaning of CNS

11. CNS
Communication
Navigation
Surveillance

12. Communication
 Communication is the exchange of voice and data
information between the pilot and air traffic controllers or
flight information centres.
Communication
Air to Ground Ground to Ground

13. Communication Facilities

15. Communication Facilities
VHF Air-to-Ground Voice Communication Facilities
Digital Voice Tape Recorder
Dedicated Satellite Communication Network
Voice Communication System
Automatic Message Switching System

16. VHF Air-to-Ground Voice Communication
Facilities
 The electromagnetic waves having frequency range 30 MHz
to 300 MHz are defined as Very High Frequency (VHF)
radio waves. VHF communication is usually suitable for
mobile applications, as these frequencies are not affected by
atmospheric noise.
 VHF Range in ATS: (117.975-136.975) MHz
 Users: Air Traffic Controllers (ATCO), Airlines/Defence
Pilots

17. Functions of VHF Unit in AAI
 Maintaining all VHF channel
 Providing radio communication between ATCO and Aircraft
 Additional standalone system is provided through J-Controller and
Transceivers at different ATC positions
 Serviceability of mains and standby equipment is around 99.9%
 All preventive and corrective maintenance schedules are performed
 The air-to-ground communications are also recorded. Analysis of
recorded communication is done by DGCA, AAI, ATC personnel for
the purpose of investigation in case of accident/incidence.

18. Facilities/Components Available With VHF Unit
 VHF Transmitter, Receiver and J-Controller/Transceiver
 RCAG (Remote Controlled Air to Ground)
 DATIS (Digital Airport Terminal Information Services)
 Dipole Antenna Integrated Communication System for Air
Traffic Control

19. VHF Transmitter
 A transmitter uses an oscillator to produce the desired radio
frequency current.
 Crystal-controlled oscillators are normally employed to
provide better frequency stability. Thinner the crystal,
higher will be the operating frequency.

20. Description of VHF Transmitter

21. VHF Receiver
 The VHF receiver has the function of selecting the desired
signal at VHF frequencies from all the other unwanted
signals, amplifying and demodulating it, and reproducing it
in the actual shape/desired manner.

22. Description of VHF Receiver

23. Digital Voice Tape Recorder (DVTR)
Audio Inputs
Distribution
Frame
Ricochet
Line Unit
NI Digitizer
Card
Ethernet/LANStorage
Server Alarm

24. Dedicated Satellite Communication Network
(DSCN)
Purposes of DSCN
 To provide security.
 To reduce manpower.
 It is economical.

25. Voice Communication System (VCS)
 Voice Communication System is a switching system that
connects various air traffic controllers’ positions to various
air-to-ground and ground-to-ground communication
systems.
 Voice switching and routing between (A-to-G and G-to-G)
communication systems and air traffic controllers’
working positions is done by using advanced
microprocessor and DSPs.

26. Basic Block Diagram of VCS System

27. Automatic Messaging and Switching System
(AMSS)
 The AMSS works on the principle of “Store and Forward”.
 The AFTN (Aeronautical Fixed Telecommunication Network) is a
world wide system of aeronautical fixed circuits provided for the
exchange of messages and/or digital data between aeronautical fixed
stations.

28. Advantages of AMSS
 Data channels are shared among communication devices,
improving the use of bandwidth.
 Messages can be stored temporarily at message switches,
when network congestion becomes a problem.
 Priorities may be used to manage network traffic.
 Broadcast addressing uses bandwidth more efficiently
because messages are delivered to multiple destinations.

29. Some Common Terms Frequently Used in AMSS
 I.P. (Internet Protocol) 32 bits
 NOTAM (NOtice To Air-Men) Information system
that includes complete information of aircraft.
 Data Base: (SQL 2005 version in use)
i. JK A NOTAM
ii. JK B Replication of JK A
iii. JK C Flight related messages
iv. JK D Replication of JK C.
 ADC (Air Defence Clearance) Number:
Enables the aircraft to move.
 FIC (Flight Information Centre) Number.

30. Navigation
 Navigation element of CNS/ATM system is meant to
provide accurate, reliable and seamless position
determination capability to aircrafts.
 Navigation is the art of determining the position of an
aircraft over the earth’s surface and guiding its progress
from one place to another.
 To accomplish this art, some sort of ‘aids’ are required by
the pilots.
 In the twentieth century, Electronics also entered in the
aviation field. Direction finders and other navigational aids
enabled the navigators to obtain fixes using electronic aids
only. Thus such aids became more popular and came into
extensive use.

31. Navigation Facilities

32. Navigation Facilities
VHF Omni-directional Range (VOR)
Distance Measuring Equipment (DME)
Instrument Landing System (ILS)

33. VHF Omni-directional Range (VOR)
 It is a type of radio navigation system for aircraft. VORs
broadcast a VHF radio signal encoding both the identity of
the station and the angle to it, informing the pilot in what
direction he/she is from the VOR station, referred to as the
radial.
 It operates in the VHF band of 112-118 MHz, used as a
medium to short range radio navigational aid. It works on
the principle of phase comparison of two 30 Hz signals.
 There are two types of VOR:
1) Conventional VOR (C-VOR)
2) Doppler VOR (D-VOR)

34. Purposes of VOR
 The main purpose of VOR is to provide the navigational
signals for an aircraft receiver that allows the pilot to
determine the bearing of the aircraft to a VOR facility.
 VOR enables the Air Traffic Controllers in the area control
radar (ARSR and ASR) for identifying the aircraft in their
scopes easily. They can monitor whether aircrafts are
following the radials correctly or not.
 VOR located outside the airfield on the extended centre line
of the runway would be useful for the aircraft for making a
straight VOR approach.

35. VOR located routes would be useful for air traffic to
maintain their PDRs (Pre Determined Routes) and
are also used as reporting points.
VORs located at radial distance of about 40 miles in
different directions around an International airport
can be used as holding VORs for regulating the
aircraft for their landing in quickest time.

36. Distance Measuring Equipment (DME)
 Distance measuring equipment is a vital navigational aid
that provides a pilot with visual information regarding his
position(distance) relative to the ground based DME.
 The facility even though possible to locate independently,
normally it is collected with either VOR or ILS.
 The DME can be used with terminal VOR and holding VOR
also.
 Frequency Range: 960 MHz to 1215 MHz. This is the most
suitable frequency range for DME, as it has less reflection
and attenuation.

37. Instrument Landing System (ILS)
 The Instrument Landing System provides a means for safe
landing of aircraft at airports under conditions of low ceiling
and limited visibility.
 The use of the system materially reduces interruptions of
services at airports resulting from bad weather by allowing
operations to continue at lower weather minimum.
 It also increases the traffic handling capacity of the airport
under all weather conditions.
 The basic philosophy of ILS is that ground installations,
located in the vicinity of the runway, transmit coded signals
in such a manner that pilot is given information indicating
positions of the aircraft s with respect to correct approach
path.

38.  The act of watching or monitoring the behaviour,
activities or other changing information, is said to be
Surveillance.
 It is mainly divided into two parts:-
1) Dependent Surveillance
2) Independent Surveillance
 In Dependent surveillance systems, aircraft position is
determined on board and then transmitted to ATC.
 In Independent surveillance systems, aircraft position is
determined from the ground.
Surveillance

39. Surveillance Facilities

40. Surveillance Facilities
Primary Surveillance RADAR
Secondary Surveillance RADAR
Surface Movement RADAR
Automatic Dependent Surveillance (ADS)
Human Machine Interface System (includes Tower
consoles, ATS)

41. RADAR
 RADAR stands for “RAdio Detection And Ranging”.
 It is an object-oriented system that uses radio waves to
determine the range, altitude, direction, or speed of objects.
 It can be used to detect aircraft, ships, spacecraft, guided
missiles, motor vehicles, weather formations, and terrain.
The radar dish (or antenna) transmits pulses of radio waves
or microwaves that bounce off any object in their path. The
object returns a tiny part of the wave's energy to a dish or
antenna that is usually located at the same site as the
transmitter.

42. Principle of RADAR
 A radar system has a transmitter that emits radio waves
called radar signals in predetermined directions. When
these come into contact with an object they are usually
reflected or scattered in many directions. Radar signals are
reflected especially well by materials of considerable
electrical conductivity—especially by most metals, by
seawater and by wet ground. Some of these make the use of
radar altimeters possible. The radar signals that are reflected
back towards the transmitter are the desirable ones that
make radar work. If the object is moving either toward or
away from the transmitter, there is a slight equivalent
change in the frequency of the radio waves, caused by the
Doppler Effect.

43. Doppler Effect
 The Doppler Effect (or Doppler Shift) is the change
in frequency of a wave for an observer moving
relative to its source. It is named after the Austrian
physicist Christian Doppler, who proposed it in 1842.
 Doppler shift depends upon whether the radar
configuration is active or passive. Active radar
transmits a signal that is reflected back to the
receiver. Passive radar depends upon the object
sending a signal to the receiver.

44. Radar Set
Primary
Radar
Pulsed
Radar
Intrapulse
Modulated
Pulse
Modulated
Continuous
Wave
Radar
Modulated Unmodulated
Secondary
Radar
Classification of RADAR sets

45. Some Common Terms Related to Radar
 ARSR (Air Root Surveillance Radar) L-Band Radar
 ASR (Air Surveillance Radar) S-Band Radar
 ASMGCS (Airport Surface Movement Ground Control
System)
 SMR (Surface Movement Radar)
 MSSR (Mono-pulse Secondary Surveillance Radar)

46. L-Band RADAR
L band, as defined by the IEEE, is the 1 to 2 GHz range of the
radio spectrum.
 Wavelength Range: 15-30 cm
 Frequency Range: 1-2 GHz

47. Simplified Block Diagram of RADAR Tx and Rx

48. Applications of L-Band Radar
 Satellite Navigation
 Telecommunication Use
 Aircraft Surveillance

49. Air Traffic Control System (ATCS)

50. Any Queries ???