Atc unit 3

Unit-3
RADAR SERVICES AND FIS
DINESHBABU V/AP/NIET

Primary Surveillance Radar (PSR)

Secondary Surveillance Radar (SSR)

Objectives of Radar Service
 For Improving airspace utilization
 For Reduceing flight delays;
 For Facilitating direct routings and more optimum
flight profiles
 For Enhancing safety

TYPES OF RADAR
1. PRIMARY SURVEILLANCE RADAR-PSR
2. SECONDARY SURVEILLANCE RADAR-SSR

PSR Radar
Heathrow Airport

ATC RADAR
 ATC RADAR = PSR + SSR
Airport Surveillance radar
Air Route Surveillance Radar
7

Principle, Advantages and Disadvantages

Primary Surveillance Radar

PSR
 In PSR ,the radio transmitter
sends out a pulse of radio
energy to the target ,of which
a very small proportion is
reflected from the surface or
structure of target aircraft
back to the radar receiver

PSR
1. Transmits radar energy detected by the aircraft by
reflected radar energy
2. Aircraft return is displayed on the ATC console at a
range and bearing with aircraft position
3. Coverage limited between 80NM to 200NM for en-
route control purpose
4. Used as a Backup to SSR
5. Target elevation is not measured by PSR.

Features of PSR
 Monitor all the aircraft in the airspace-upto a distance of
65 NM at S band (2.7 to 2.9 GHz) @ 25 KW peak -Av 2 KW
@ 15 rpm.
 Operating totally independently of the aircraft target.
 Weather conditions detected in six levels of rain intensity
 Provide range & direction information from the reflected
signal from the aircraft.
 Passive Radar-no action from the aircraft required to
provide to ATC

Advantages of PSR
 Operates independently irrespective of target
 No Action Required from the Aircraft

Radar Vectoring-for guidance
 A heading issued to the Aircraft for navigational
guidance by a Radar is called Vectoring in Radar
 If the aircraft to fly straight on the screen, Radar
Vectoring is = fly heading 360.
 If the aircraft to fly east, or to RHS, Radar
Vectoring= heading 090

Disadvantages
 TX signal limited by ‘line of sight’ interrupted by
buildings, hills & mountains.
 More power be radiated for getting returns from the
target & little power is received.
 Hence displayed target will be fading (not clear).

Secondary Surveillance Radar

SSR-Secondary Surveillance Radar
Provide
1. Range,
2. Bearing,
3. Altitude and
4. Identity (call sign) of an aircraft.

SSR-Beacon

Characteristics of Secondary Surveillance
Radar (SSR)
 An Active Surveillance Radar for accurate information working
at 1030 MHz with Mode S interrogation
 Size Smaller than PSR, be mounted either single or Combined
with PSR (ARS11)
 Aircraft detected through 'transponder‘ fitted at the aircraft.
 Transponder - radio TX & RX receiving on one frequency
(1030 MHz) and transmitting on another (1090 MHz).
 SSR detects 1. identification of the aircraft, 2. the height of
aircraft, 3. speed and 4.direction of flight.

Radar Beacon At Schipol Airport

Schematic of SSR & PSR

Functioning of SSR
1. A ground-based transmitter, the interrogator, very
specific types of signals (1030 and 1090 MHz)
broadcasts a radio signal to the aircraft
2. A transponder on the aircraft receive and reply to this
signal
3. Transponder replies with a different series of pulses that
gives aircraft identifier and altitude
4. If a plane did not respond correctly, then the target is
an enemy aircraft
 PSR and SSR are synchronized, both returns will be
displayed on the ATC console

Transponder
 Must be inspected every 24 calendar months (controlled
airspace)

Transponder to Interrogator
 A radar which the object to be detected fitted
transponder
 Radar pulses transmitted from interrogator received in
Transponder
 Transponder send a distinctive transmission to the
Interrogator.
 Reply transmission received back at the
transmitter/receiver site for processing and displayed
at ATC facility

SSR Identification Procedure
1. SSR transponder selected on Mode 3/A (4096 codes)
and Mode C simultaneously
2. Pilots will maintain the same setting in the
Transponder
3. ATC instruct the departure Flight to operate the
transponder
4. Eg : 7600-a/c cannot receive radar signal
7500 – a/c suffering from unlawful interference
(hijack)

Transponder codes A,C & S
 Mode A -basic SSR Mode aircraft's transponder for
Aircraft Identification using a 4 Digit Octal Code( two
pair of signal with interval of 8ms-while receiving
20.6ms)
 Mode C-for altitude Pressure with 4 digit Octal Code
identification
 Mode S- for Multipurpose identification using 2 µS pulse
from a Single reply with multiple formats from the
Aircraft called Mono pulse-widely used

SSR Radar Screen-3D Vector Scan

Advantages of Secondary Surveillance Radar
SSR
 Higher Range
 Low power required to radiate the signals, thus
reduce the cost.
 Providing more information: aircraft’s identity,
altitude & speed.
 Giving a clearer display
 Easier to identify aircraft on SSR (interrogation)

PSR vs. SSR
1 Give Direction, height
and distance (DME)
Give additional info of
signal identification and
altitude
2 Works on Passive Echo Works on Active Echo
(Thru Transponder)
3 No reflected signal
processing
Reflected signal
processing
4 No interrogation Interrogation
5 Back up to SSR By itself

ATC RADAR
SSRPSR
By reflection of an Echo
Pulse from a Site on a Monitor
For Airport En-route Surveillance
Thru a Transponder
At the Aircraft
A Passive Radar An Active Radar

Types and Purpose

Radar Service Areas
1. AERODROME CONTROL SERVICE AREA-for
apron management at the aerodrome
2. AREA CONTROL SERVICE AREA- for enroute air
traffic
3. APPROACH CONTROL SERVICE AREA for
arriving and departing air traffic
34

Aerodrome Control Service
 ADCS Service given to the aircraft from the control
tower (–> TWR) with its extended field of vision, to
start engines for take off or to land
 ADCS directs taxiing aircraft and manages airborne
traffic in the immediate vicinity of the airport.

Enroute Traffic Control Centre at
Atlanta-USA

Area Control Service
 ACS for the safe flow of traffic along airways (–> En-
route) and in certain portions of terminal control areas
(–> APP).
 ACS cover for various altitudes and geographic sectors

Minimum Safe Altitude-MSA
 An Altitude-Allowing adequate vertical clearance
from terrain and manmade obstacles, and allowing
proper navigational functions.
 Depending on VFR & IFR
 For VFR flights 1000’ in non mountainous area and
2000’ in mountanous area

Minimum Safe Altitude

Minimum Enroute Altitude-MEA
 Lowest published altitude of an aircraft flying on IFR
legally on a given route
 MEA listed as a Number-6500-the lowest minimum
altitude ensuring signal coverage from navigational
aids
 Minimum Enroute Altitude-determined by the local
terrain and navigation equipment –
 At night aircraft not allowed to descend a min enroute
altitude

FIS on Screen

Air space Traffic In Miami

ARTCC-Air Route Traffic Control
Centre-Enroute
 Air Route Surveillance Centre=Air Route Traffic
Control Centre.
 Objective: For providing air traffic control service
on IFR flight plan in controlled airspace & on
Enrouote
 For assistance service to VFR Flight
44

Approach Control Service
 Approach control service for flights arriving and
departing from an airport in a specific control zone (–
> CTR) and in terminal control area (usually within a
50 km radius of the airport)

Definition, Techniques in each, Radar Separation
Control

Non Radar Control
1. A method of providing Air Traffic Control service
without the use of radar, used in Sparingly
populated Areas
2. Used in Low Traffic Airports

Radar Control Services
1. Services for D & E Airspace
2. Radar Advisory Service to F Airspace
3. Radar Flight Information Service to
G airspace

( Horizontal )Radar Separation
Minimum
 5 NM horizontal radar separation up to 60 NM from
radar head except 6 NM horizontal radar separation to
aircraft in the approach and departure phases of flight
shall be applied
 the LIGHT an aircraft operating directly behind the
HEAVY aircraft at the same altitude or less than 1000 ft
below

Techniques of Non Radar Control
1. By Horizontal separation between Aircrafts, based
upon time, or routes, or aircraft position based on
ground-based navigation aids
2. By Altitude grouping -the easiest and most common
method for cruising altitude as in trans-oceanic
sectors.
3. By route intersection points (fix posting area) easiest
Non Radar control

Types of Non Radar Separation
1. Vertical separation
2. Longitudinal separation
3. Lateral separation
4. Geographical separation
5. Omni Track Separation
6. Visual separation

When light aircraft operating directly behind a
Heavy aircraft

When light aircraft crossing behind a Heavy
Aircraft

Co-ordination between radar / non radar control
1. Adequate separation between aircraft maintained
between the radar-controlled and non radar control.
2. Radar separation based on the use of RPS shall be
applied
3. Under no circumstances the edges of the radar position
should touch or overlap
4. Radar separation be maintained between the radar-
controlled flights and any other observed radar position

Approach Radar Procedure
 Sequence of arriving aircraft informed by the
approach radar controller to Aerodrome controller
 pilot is advised the type of approach as well as the
runway to be used

Radar Separation minimum & coordination

Performance checks – use of radar in area and approach control services
– assurance control and co-ordination between radar / non radar
control – emergencies

PERFORMANCE CHECKS
1. Adjusting the radar display
2. Carrying out checks on the accuracy of the display
as per ATC manual
3. Functional capabilities of the radar system is
satisfied by the controller
4. If there is any difficulty in the peformance, it is
reported

RADAR IDENTIFICATION
 PSR Identification Procedures
 SSR Identification Procedures

PSR Identification
I. By Departing Aircraft Method
II. By position report method-position
III. By Turn Method

PSR Identification
1. Departing Aircraft Method: By correlating an observed radar
position indication with an just departed aircraft (within 1 NM of
runway)
2. By position report method-position indication with an aircraft
reporting its position
3. By Turn Method: An aircraft identified by ascertaining the
aircraft heading

SSR Identification
1. Through a Call Sign or Code
2. By Direct recognition
3. By transferring Radar Identification to the pilot
4. By observation to a set of Codes

SSR Identification
1. Aircraft identification by a SSR Label thru a
code/call sign
2. By Direct recognition of the aircraft identification of
a Mode S-equipped aircraft in a radar label;
3. By transfer of radar identification
4. By observation of compliance with an instruction to
set a specific code;

Emergencies
 In the event of an emergency, every assistance shall be
provided by the radar controller, and
 The procedures as per the situation
 Progress of an aircraft in emergency shall be
monitored and plotted on the radar display until the
aircraft passes out of radar coverage,

Co-ordination and emergency procedures

Services of the Air
1. Area Control Service-for Enroute
2. Approach Control Service-50Km radius
3. Aerodrome Control Service-thru’ the Control tower
for starting the engine, take off and landing

Stages in Co-ordination between ATC
Units
A. Announcing the flight and conditions for transfer of
control
B. Coordination of transfer and agreement on the
control conditions
C. Transferring of control to the accepting ATC unit or
control sector.

Important Coordination Zones
1. Between ATC Centres
2. Between Area Control Service and Approach
Control Service
3. Between Approach Control Service and Aerodrome
control Service
4. Between ATC and Military service
5. Between Met and ATC

Coordination between Area Control Service & approach control Service
 A unit providing approach control service will issue
clearances to any aircraft released to it by an ACC
without reference to the ACC.
 Take-off and Clearance ExpiryTimes –coordinate the
departure with unit providing approach control
service;
 provide en-route separation for departing aircraft

Rules of the Air
1. Protect person and property
2. Minimum Safe Altitude
3. Cruising Levels
4. Dropping or Spraying
5. No towing by another aircraft
6. No acrobatic flight
7. No flying in Restricted Areas
8. Right of way for heading and speed

Sigmet,FIS Scope,Air reporting on designated route,Air
data transmission, Alerting service

SIGMET-Significant Meteorological
Information
 An advisory service providing meteorological
information for the safety of all aircrafts
 two types of SIGMET-s, convective and non-convective
 Non connective Sigmet for severe turbulence or icing
or sandstorm
 Connective sigmet for thunderstorm

Vaisala (UK) Sigmet

Scope of Flight Information service
1. SIGMET
2. information regarding volcanic activity, volcanic eruptions and
volcanic ash clouds;
3. Info concerning the release into the atmosphere of radioactive
materials or toxic chemicals;
4. Information on changes in the serviceability of navigation aids
5. Information on changes in condition of aerodromes and
associated facilities,
6. including information on the state of the

Air Reports on Designated Air
Route
1. Moderate to severe Turbulence
2. Severe Icing
3. Hail
4. cumulonimbus Cloud (type of cloud tall, dense, and
involved in thunderstorms)
5. Any met condition in the opinion of the pilot to
affect aircraft operation

Cumulonimbus Cloud

Methods of Transmission of Air
Data
A. By method of directed transmission on the initiative
of the appropriate ATS unit to an aircraft
B. By an acknowledged transmission to all aircraft
concerned
C. By a Broadcast
D. By a data link

Air Traffic Advisory Service
 objective of the air traffic advisory service is to make
information on collision hazards more effective than it
would be in the mere provision of FIS
 It may be provided to aircraft in IFR flights in advisory
airspace or on advisory routes (Class F airspace)

An air traffic services unit providing
air traffic advisory service-Shall
 Advise the aircraft to depart at the time specified and
to cruise at the levels indicated in the flight plan
 Suggest a course of action to avoid any hazard
 Passing the traffic information to the aircraft as given
by area control service

Alerting Service Phases
A. Uncertainty in phase-no communication from
aircraft in less than 30’
B. Alerting phase no news of aircraft following A
C. Distressing Phase following A,B -with widespread
enquiries

Alerting Service
 To provide service when no communication from the
aircraft in less than 30’
 Alert in phase when communication with the aircraft
fail

 Provided to all aircraft as Traffic control service

Flight Information Service-Chennai
1. Lateral and Vertical Airspace
2. Unit providing Service-ACC Chennai
3. Call Sign-Chennai Radar- RSR
4. Frequency-118.9 MHz,125.7 MHz
5. Airspace under ATS=F
6. Airspace outside ATS=G

Atc unit 3

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Atc unit 3