AAI Airport Report on GIS, Solar, STP, BHS, Runway Lighting

Airports authority of india
n.S.C.B.I. airport, Kolkata- 700 052
A Project Report On Summer Vocational Training in:-
GIS, Service Yard, Solar Energy, STP,
Baggage Handling System, Runway Lighting, etc.
(11/06/18 - 29/06/18)
SUBMITTED BY:-
 Debjyoti Mitra
 Nidhi Kumari
 Subham Mondal
 Arijit Kumar Haldar
 Suman Mondal
Electrical Engineering – B.E. 4th
Year
Of
JADAVPUR UNIVERSITY

Contents
Subject Page Number
► Acknowledgement....................................................................................................1

► Introduction..............................................................................................................2
► General Overview of AAI........................................................................................3
► GIS...........................................................................................................................7
► Solar Energy System...............................................................................................14
► Service Yard............................................................................................................16
► Sewage Treatment Plant..........................................................................................21
► Baggage Handling System......................................................................................29
► Runway Lighting System........................................................................................32
► Cargo Handling System..........................................................................................38
► Conclusion..............................................................................................................45
► Bibliography...........................................................................................................46

Airport Authority of India
Netaji Subhas Chandra Bose
International Airport
Page | 1
Acknowledgement
We take this opportunity to express our profound gratitude and deep regards to our guides Mr. S.
Bhattacharya, DGM (EE), Mr. S.K. Biswas, AGM (EE) & Mr. Saubhik Pan, SM (EE) and for their
exemplary guidance, monitoring and constant encouragement throughout this training. Their constant
guidance, and support helped as know how the airport works, and learn about the various techniques used
for Electrical uses, maintenance and safety within the airport. Without them this exploration could never
have been materialized.
We are obliged to the staff members at AAI of NSCBI airport, for the valuable information provided by
them in their respective fields. We are grateful for their cooperation during the period of our assignment.
Special regards
I take this opportunity to express my sincere gratitude to Prof. Dr. S. Paul, Head of the Electrical
Engineering Department, Jadavpur University, Kolkata who gave the permission to be associated with
one of the best organisation, Airports Authority of India, NSCBI Airport, Kolkata.

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Introduction
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. It manages 133 airports and covers 2.8 million square
nautical miles area which includes oceanic area of 1.7 million square nautical miles.
During the year 2008-09, AAI handled aircraft movement of 1306532 nos. [International 270345
& domestic 33785990] and the cargo handled 499418 tones [international 318242 & domestic
181176]. AAI provides CNS/ATM services at all the civil airports in the country. The 125
airports managed by AAI includes 15 international,7 custom,25 civil enclaves and 78 domestic
airports.

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GENERAL OVERVIEW
We have developed a general overview regarding what role the Airport Authorities of India plays in the
proper functioning and maintenance of the Netaji Subhas Chandra Bose International Airport.
About ICAO
The International Civil Aviation Organization (ICAO) is a UN specialized agency, established by States in
1944 to manage the administration and governance of the Convention on International Civil Aviation
(Chicago Convention).
ICAO works with the Convention’s 192 Member States and industry groups to reach consensus on
international civil aviation Standards and Recommended Practices (SARPs) and policies in support of a
safe, efficient, secure, economically sustainable and environmentally responsible civil aviation sector.
These SARPs and policies are used by ICAO Member States to ensure that their local civil aviation
operations and regulations conform to global norms, which in turn permits more than 100,000 daily
flights in aviation’s global network to operate safely and reliably in every region of the world.
In addition to its core work resolving consensus-driven international SARPs and policies among its
Member States and industry, and among many other priorities and programmes, ICAO also coordinates
assistance and capacity building for States in support of numerous aviation development objectives;
produces global plans to coordinate multilateral strategic progress for safety and air navigation;
monitors and reports on numerous air transport sector performance metrics; and audits States’ civil
aviation oversight capabilities in the areas of safety and security.
Bureau of Civil Aviation Security
The Bureau of Civil Aviation Security (BCAS, Hindi: नगर विमानन सुरक्षा ब्यूरो) is an attached office of the
Ministry of Civil Aviation of India. Its head office is on the first through third floors of the A Wing of the
Janpath Bhawan along Janpath Road in New Delhi. The agency has eight regional offices, located at
Indira Gandhi Airport in Delhi, ChhatrapatiShivaji International Airport in Mumbai, Chennai International
Airport in Chennai, Netaji Subhas Chandra Bose International Airport in Kolkata, Amritsar, Ahmedabad,
Guwahati and Hyderabad.
Establishment of airport
For establishing an airport first land is selected. The land is selected on the basis of the following
criteria:-
• Direction of air flow
• Direction of sun rise and sun set
• Location of nearby airport
• Location of nearby river
• Location of nearby forest/desert/hill
• Latitudinal and longitudinal level
• Temperature and annual rainfall of the area
• City population and many more….

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Runway
According to the International Civil Aviation Organization (ICAO), a runway is a "defined rectangular area
on a land aerodrome prepared for the landing and takeoff of aircraft". Runways may be a man-made
surface (often asphalt, concrete, or a mixture of both) or a natural surface (grass, dirt, gravel, ice, or
salt).
Naming
Runways are named by a number between 01 and 36, which is generally the magnetic azimuth of the
runway's heading in decadegrees. This heading differs from true north by the local magnetic declination.
A runway numbered 09 points east (90°), runway 18 is south (180°), runway 27 points west (270°) and
runway 36 points to the north (360° rather than 0°). When taking off from or landing on runway 09, a
plane would be heading 90° (east).
A runway can normally be used in both directions, and is named for each direction separately: e.g.,
"runway 33" in one direction is "runway 15" when used in the other. The two numbers usually differ by
18 (= 180°).
If there is more than one runway pointing in the same direction (parallel runways), each runway is
identified by appending Left (L), Center (C) and Right (R) to the number to identify its position (when
facing its direction) — for example, Runways One Five Left (15L), One Five Center (15C), and One Five
Right (15R). Runway Zero Three Left (03L) becomes Runway Two One Right (21R) when used in the
opposite direction (derived from adding 18 to the original number for the 180 degrees when
approaching from the opposite direction). In some countries, if parallel runways are too close to each
other, regulations mandate that only one runway may be used at a time under certain conditions
(usually adverse weather).
Declared distances
Runway dimensions vary from as small as 245 m (804 ft) long and 8 m (26 ft) wide in smaller general
aviation airports, to 5,500 m (18,045 ft) long and 80 m (262 ft) wide at large international airports built
to accommodate the largest jets, to the huge 11,917 m × 274 m (39,098 ft × 899 ft) lake bed runway
17/35 at Edwards Air Force Base in California – developed as a landing site for the Space Shuttle.
Takeoff and landing distances available are given using one of the following terms:
TORA
Takeoff Run Available – The length of runway declared available and suitable for the ground run of an
airplane taking off.
TODA

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Takeoff Distance Available – The length of the takeoff run available plus the length of the clearway, if
clearway is provided.
(The clearway length allowed must lie within the aerodrome or airport boundary. According to the
Federal Aviation Regulations and Joint Aviation Requirements (JAR) TODA is the lesser of TORA plus
clearway or 1.5 times TORA).
ASDA
Accelerate-Stop Distance Available – The length of the takeoff run available plus the length of the
stopway, if stopway is provided.
LDA
Landing Distance Available – The length of runway that is declared available and suitable for the ground
run of an airplane landing.
EMDA
Emergency Distance Available – LDA (or TORA) plus a stopway.
(Runway sign at Madrid-Barajas Airport, Spain)
Sections of a runway
• The runway thresholds are markings across the runway that denote the beginning and end of
the designated space for landing and takeoff under non-emergency conditions.[11]
• The runway safety area is the cleared, smoothed and graded area around the paved runway. It
is kept free from any obstacles that might impede flight or ground roll of aircraft.
• The runway is the surface from threshold to threshold, which typically features threshold
markings, numbers, and centerlines, but not overrun areas at both ends.
• Blast pads, also known as overrun areas or stopways, are often constructed just before the start
of a runway where jet blast produced by large planes during the takeoff roll could otherwise erode the
ground and eventually damage the runway. Overrun areas are also constructed at the end of runways
as emergency space to slowly stop planes that overrun the runway on a landing gone wrong, or to
slowly stop a plane on a rejected takeoff or a takeoff gone wrong. Blast pads are often not as strong as
the main paved surface of the runway and are marked with yellow chevrons. Planes are not allowed to
taxi, take off or land on blast pads, except in an emergency.
• Displaced thresholds may be used for taxiing, takeoff, and landing rollout, but not for
touchdown. A displaced threshold often exists because obstacles just before the runway, runway
strength, or noise restrictions may make the beginning section of runway unsuitable for landings. It is
marked with white paint arrows that lead up to the beginning of the landing portion of the runway.

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Runway markings
There are runway markings and signs on most large runways. Larger runways have a distance remaining
sign (black box with white numbers). This sign uses a single number to indicate the remaining distance of
the runway in thousands of feet. For example, a 7 will indicate 7,000 ft (2,134 m) remaining. The runway
threshold is marked by a line of green lights.
There are three types of runways:
• Visual runways are used at small airstrips and are usually just a strip of grass, gravel, ice,
asphalt, or concrete. Although there are usually no markings on a visual runway, they may have
threshold markings, designators, and centerlines. Additionally, they do not provide an instrument-based
landing procedure; pilots must be able to see the runway to use it. Also, radio communication may not
be available and pilots must be self-reliant.
• Non-precision instrument runways are often used at small- to medium-size airports. These
runways, depending on the surface, may be marked with threshold markings, designators, centerlines,
and sometimes a 1,000 ft (305 m) mark (known as an aiming point, sometimes installed at 1,500 ft (457
m)). They provide horizontal position guidance to planes on instrument approach via Non-directional
beacon, VHF omni-directional range, Global Positioning System, etc.
• Precision instrument runways, which are found at medium- and large-size airports, consist of a
blast pad/stopway (optional, for airports handling jets), threshold, designator, centerline, aiming point,
and 500 ft (152 m), 1,000 ft (305 m)/1,500 ft (457 m), 2,000 ft (610 m), 2,500 ft (762 m), and 3,000
ft(914 m) touchdown zone marks. Precision runways provide both horizontal and vertical guidance for
instrument approaches.

Page | 7
POWER SYSTEM DESIGNING AT
aiRPORT Authorities of india- gis
We have observed two incoming sections of power supply at the Airport Authorities of
India.
 The Open Yard sector
 The Service Yard sector
We have paid a visit to each of these units. In the following statements we will briefly mention what we
have learnt from these visits.
THE OPEN YARD (GIS):
Here we saw 3 transformers, each rated at 8 M.V.A., 33/11-6 kV. There are two incoming Feeders of
CESC coming from
 3 way SIE RMU at Airport
 NCSS GIS
That apart there is a Tie Feeder.
The entire incoming unit has 8 Gas Insulated Switchgear (Circuit Breaker) units. There are 3 Supply and 3
Outgoing Breakers with 2 Bus Coupler Breakers. The outgoing breakers feed the primary of the
transformers with 33kV. The secondary of the transformer is developing 6kV. This 6kV supply is being
catered to the 6kV distribution panel through Underground cable.
The Operating of the whole Unit is being done by SCADA.
The various Load distribution Centres from the Open Yard are:
 RK S/S FEEDER
 NEW TECHNICAL AREA COMPLEX
 SNB S/S
 APC S/S (2)
 AIRPORTS AUTHORITY OF INDIA COLONY S/S
 HIGH-TENSION AUTOMATIC POWER FACTOR CORRECTION PANEL (2)
 CARGO SUBSTATION
 ADMIN OFFICE
 VIVEKANANDA S/S FEEDER
 INTAKE S/S
We observed the APFC Panel. It has been installed to improve the operating Power factor. There were
two panels rated to operate at 6kV. The capacitor banks installed were rated at 300kVar(x2), 600kVar
and 1200kVar. In all there are 2 installations of (300+300+600+1220=) 2400kVar capacity. Depending
upon the inductive load in the circuit, the required capacitive action is switched on. The units installed
have reactors and insulators installed. The purpose of the reactor is to reduce the surge current drawn
by the capacitors and the insulations are installed to minimize the vibration of the units.
We saw the RTCC panel which is used for the operation of the Automatic Voltage Regulator. AVR
controls the transformer tapping on primary to control the output voltage of the secondary at 6kV.

Page | 8
There is an Earth Switch in the main panel which is used to isolate the high tension feeder or circuit
busbars before doing any maintenance work on the system.
It is pertinent on our part to mention what we saw in the transformer Unit.
 The units were installed on gravel. During Short circuit current Step and Touch potential
increases. So to reduce the step potential and touch potential when operators work on switch
yard, Stones in the substation is provided
(Step potential : It is the potential developed between the two feet on the ground of a man or animal when
short circuit occurs. This results in flow of current in the body leads to electrical shock.
Touch potential: It is the potential that is developed between the ground and the body of the equipment when
a person touches the body during fault condition. When operating personnel touch an electrical
equipment during short circuit condition, fault current flows through the human body. This is defined as
touch potential.)
 We noticed the Nitrogen Injection based Fire Protection System(NIFPS). The system shall work on
the principle of DRAIN AND STIR and on activation, it shall drain a pre- determined quantity of oil
from the tank top through outlet valve to reduce the tank pressure and inject nitrogen gas at high
pressure from the lower side of the tank through inlet valves to create stirring action and reduce
the temperature of top oil surface below flash point to extinguish the fire. Conservator tank oil
shall be isolated during bushing bursting, tank explosion and oil fire to prevent aggravation of fire.
 We have observed the Earth Fault and Over-current Protection Relay. The over current relays
cannot distinguish between external short circuit, over load and internal faults of the transformer.
For any of the above fault, backup protection i.e. over current and earth fault protection
connected to in-feed side of the transformer will operate.
 We observed the Conservator tank, the Breather and the On-Load tap changer.
 Buchholz relay: The relay is connected to the oil piping between the conservator and oil tank of a
transformer. The piping between the main tank and conservator is arranged so that any gas
evolved in the main tank tends to flow upward toward the conservator and gas detector relay. On
a slow accumulation of gas, due perhaps to slight overload, gas produced by decomposition
of insulating oil accumulates in the top of the relay and forces the oil level down. A float switch in
the relay is used to initiate an alarm signal. Depending on design, a second float may also serve to
detect slow oil leaks. If an electric arc forms, gas accumulation is rapid, and oil flows rapidly into
the conservator. This flow of oil operates a switch attached to a vane located in the path of the
moving oil. This switch normally will operate a circuit breaker to isolate the apparatus before the
fault causes additional damage.
 Pressure Relief Valve: This protection detects a sudden rate-of-increase of pressure inside the tap
changer oil enclosure. When the pressure in front of the piston exceeds the counter force of the
spring, the piston will move operating the switching contacts. The micro switch inside the
switching unit is hermetically sealed and pressurized with nitrogen gas.

Page | 9
 Neutral Grounding Resistor: Neutral Grounding Resistors is used in power
transformers to limit fault current to prevent unwanted current damages. It is
employed in AC distribution networks to limit fault current which would flow
from transformer neutral star point in the event of an earth fault in a systems.
It is used when neutral of supply is accessible and its own impedance is not
enough to limit fault current .The ratings of protection relay within required
time. For grounding neutral of transformer and generator, resistors up to 33kV
are offered for fault short duration 30 sec., 60 sec and continuous etc.
Gas-insulated switchgear (GIS) 72.5 - 1200 kV
Pioneer and technology leader driving GIS innovations
Gas-insulated high-voltage switchgear (GIS) is a compact metal encapsulated switchgear
consisting of high-voltage components such as circuit-breakers and disconnectors, which can be
safely operated in confined spaces. GIS is used where space is limited, for example, extensions,
in city buildings, on roofs, on offshore platforms, industrial plants and hydro power plants. ABB
has always been and continues to drive innovation in GIS technology in ratings, operations,
switching technology, smart control and supervision, and compactness. As a result, ABB’s GIS
offers outstanding reliability, operational safety and environmental compatibility. It provides a
complete range of products for all ratings and applications from 72.5 kV to 1200 kV matching
current and future requirements for modern switchgears.
Applications
 Power transmission
 Airports
 Integration of renewable power generation units to the grid
 Railways
Netaji Subhas Chandra Bose International Airport
GIS Building
In GIS building one CESC feeder of 33KV is fitter with parallel connected 1250A gas insulated
switch gears, which then goes to the transformer rated 8MVA.

Page | 10
Transformer
GIS building uses three 8MVA transformers with DY11 configuration, which steps down 33KV
to 11/6KV. Tap changing from 11 to 6 or vice versa is done by using Remote tap changer control
panel (RTCC). Remote tap changer control panel is a programmable device to control the output
of the transformer through online tap changers (OLTC) units fitted in the transformer through
control cables. The neutral of the secondary is grounded through a resistance called the neutral
grounding resistance.

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Neutral Grounding Resistors
Neutral Grounding Resistor systems can be inserted between the neutral and ground in a power
system to provide ground fault protection through resistance. The fundamental purpose of a
Neutral Grounding Resistor (NGR) is to limit ground fault currents to safe levels so that all the
electrical equipment in a power system is protected. Neutral Grounding Resistors are also
commonly referred to as Neutral Earthing Resistors and Earth Fault Protection Resistors.
Protection used in transformer:
Bushing
In electric power, a bushing is an insulated device that allows an electrical conductor to pass
safely through a grounded conducting barrier such as the case of a transformer or circuit breaker.
Bushings are typically made from porcelain, though other materials are possible.
All materials carrying an electric charge generate an electric field. When an energized conductor
is near a material at earth potential, it can form very high field strengths, especially where
the field lines are forced to curve sharply around the earthed material. The bushing controls the
shape and strength of the field and reduces the electrical stresses in the insulating material.
Conservator Tank of a Transformer
This is a cylindrical tank mounted on supporting structure on the roof the transformer main tank.
The main function of conservator tank of transformer is to provide adequate space for expansion
of oil inside the transformer.
When transformerr is loaded and when ambient temperature rises, the volume of oil inside
transformer increases. A conservator tank of transformer provides adequate space to this
expanded transformer oil. It also acts as a reservoir for transformer insulating oil.

Page | 12
Buchholz Relay
Buchholz relay in transformer is an oil container housed the connecting pipe from main tank to
conservator tank. It has mainly two elements. The upper element consists of a float. The float is
attached to a hinge in such a way that it can move up and down depending upon the oil level in
the Buchholz relay Container. One mercury switch is fixed on the float. The alignment of
mercury switch hence depends upon the position of the float. The lower element consists of a
baffle plate and mercury switch. This plate is fitted on a hinge just in front of the inlet (main tank
side) of Buchholz relay in transformer in such a way that when oil enters in the relay from that
inlet in high pressure the alignment of the baffle plate along with the mercury switch attached to
it, will change.
In addition to these main elements a Buchholz relay has gas release pockets on top. The
electrical leads from both mercury switches are taken out through a molded terminal block. The
Buchholz relay working principle of is very simple. Buchholz relay function is based on very
simple mechanical phenomenon. It is mechanically actuated. Whenever there will be a minor
internal fault in the transformer such as an insulation faults between turns, break down of core of
transformer, core heating, the transformer insulating oil will be decomposed in different
hydrocarbon gases, CO2 and CO. The gases produced due to decomposition of transformer
insulating oil will accumulate in the upper part the Buchholz container which causes fall of oil
level in it.

Page | 13
Nitrogen Injection Fire Protection System
Nitrogen injection & evacuation system can be used to protect the transformers from fire &
explosions.
HOW A TRANSFORMER EXPLODE & GET FIRE
 An Arc is generated due to any internal fault in the Transformer.
 And a high energy flows through transformer.
 Which lead to decomposition of insulation/oil at high temperature.
 Top oil surface attains temperature higher than ignition point.
 Huge thermal energy is generated thereby emitting combustible gases.
 Pressure built-up resulting in tank rupture normally at top cover.
 Hot oil when comes in contact with the oxygen catches fire.
Why to use nitrogen injection system
 On activation, the system extinguishes the Fire within seconds.
 It prevents the Transformer from explosion.
 Nitrogen Gas is inert and does not react with transformer oil.
 It is completely Non-hazardous
 It provides best cooling effect to the oil inside the Transformer.
 Forms insulating layer (Thermal) on top surface of the oil.
 Easily available and in-expensive.
 Environment friendly.

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Solar Energy harnessing at AAI
Solar power harnesses the natural energy of sun to produce electricity. Solar energy is renewable
source of energy.
1. The total solar energy production of AAI is 17MW.
Bikram solar(2MW) and Sterling (15MW)
2.The main solar panel which we studied was rooftop mounted solar panel of capacity 2MW
and 100KW.
3.Solar cell or photovoltaic cells is an electrical device that converts the energy of light directly
into electricity by photovoltaic effect.
4.Solar cells are made up of monocrystalline silicon whose efficiency is more but is bit costly.
Polycrystalline can be used as it is bit cheaper but efficiency is less. A monocrystalline panel is
shown .
5.In one unit there are 60 cells in series each of capacity 0.5 Volt .Therefore a single unit is of
30volts.
6.In one string there are 24 modules and 24*10 module is fed to a single inverter which are
connected through isolators.
7.There are three string inverter each of DC-62.5kw peak and AC output 50kw.
8.The panel are portrait type with minimum distance of 4m between them so that shadow of one
panel doesn’t fall upon another.

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The above picture shows the solar panel present at authority's main building.
9.The cells are connected in series but later on strings are connected in parallel so that if any
problem occurs in one unit entire system need not to be replaced.
10.To use this generated A.C underground evacuation system is used.
11.The main problem of solar energy is that it’s efficiency is very low as it totally depends upon
environmental factors like weather

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Service yard
There are three incomers each of 33 kV. Two of them are from CESC and
one from open yard.
These incomers are connected through circuit breakers and interlock
33kv,800A,31.5kA Isolator panel(SF6 circuit breaker) connection is made
which connects incomer to transformer.
Transformer are of capacity 20MVA,33/11 kV DYn11,ONAN with RTCC panel,
AVR ,OLTC and percentage impedance 10.24%.
They are earthed through neutral grounding resistors
These step down transformer step down the voltage to 11kv.
The third line shown is from Open yard .
Buses are connected through bus coupler and circuit breaker. The outgoing
is of 11 kV one of them is fed to AC panel board and two to 11kv HT panel
board.

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(Safety helmet and the CBs at Service Yard)

Page | 18
These are further connected through their own transformer whose
endings are fed to DG set and ATS panel .The excitation voltage of DG set is
26.7v DC.
HT panel board is shown .They are connected through 11KV,1250A bus bar
and 11kv,1000A 26kA VCB.
They are further connected to ATS panel boards.
.
The other panels are Ac panel board and chiller panel board.Chiller panel
board is as shown in the line diagram.Two informers are there – one from
AC panel board and another from HT panel board connected through bus
coupler.
The general overview of chiller panel board is shown in the line diagram
below:-

Page | 19

Page | 20
After chiller panel board let’s have a look on AC panel board.This board
is connected from incomer through a transformer of capacity 2MVA
11kv/433v oil type and whose percentage impedance is 6.25%.all are
delta star transformer.
The outgoing of this transformer is fed to ATS whose one end is
connected through DG set..
The general overview is as shown in the line diagram below:-
DG set acts as backup in case of failure of supply from CESC or any fault
due to which the system cannot work.
DG set can act as backup for maximum 3 days.

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Sewage treatment plant
Sewage treatment is the process of removing contaminants from wastewater, primarily from
household sewage. Physical, chemical, and biological processes are used to remove
contaminants and produce treated wastewater (or treated effluent) that is safer for the
environment. A by-product of sewage treatment is usually a semi-solid waste or slurry,
called sewage sludge. The sludge has to undergo further treatment before being suitable for
disposal or application to land.
Sewage treatment may also be referred to as wastewater treatment. However, the latter is a
broader term which can also refer to industrial wastewater. For most cities, the sewer
system will also carry a proportion of industrial effluent to the sewage treatment plant which
has usually received pre-treatment at the factories themselves to reduce the pollutant load. If
the sewer system is a combined sewer then it will also carry urban runoff (stormwater) to the
sewage treatment plant. Sewage water can travel towards treatment plants via piping and in a
flow aided by gravity and pumps. The first part of filtration of sewage typically includes a bar
screen to filter solids and large objects which are then collected in dumpsters and disposed of
in landfills. Fat and grease is also removed before the primary treatment of sewage.
Overview
Sewage collection and treatment is typically subject to local, state and federal regulations and
standards.

Page | 22
Treating wastewater has the aim to produce an effluent that will do as little harm as possible
when discharged to the surrounding environment, thereby preventing pollution compared to
releasing untreated wastewater into the environment.
Sewage treatment generally involves three stages, called primary, secondary and tertiary
treatment.
 Primary treatment consists of temporarily holding the sewage in a quiescent basin
where heavy solids can settle to the bottom while oil, grease and lighter solids float to
the surface. The settled and floating materials are removed and the remaining liquid
may be discharged or subjected to secondary treatment. Some sewage treatment plants
that are connected to a combined sewer system have a bypass arrangement after the
primary treatment unit. This means that during very heavy rainfall events, the
secondary and tertiary treatment systems can be bypassed to protect them from
hydraulic overloading, and the mixture of sewage and stormwater only receives
primary treatment.
 Secondary treatment removes dissolved and suspended biological matter. Secondary
treatment is typically performed by indigenous, water-borne micro-organisms in a
managed habitat. Secondary treatment may require a separation process to remove the
micro-organisms from the treated water prior to discharge or tertiary treatment.
 Tertiary treatment is sometimes defined as anything more than primary and secondary
treatment in order to allow ejection into a highly sensitive or fragile ecosystem
(estuaries, low-flow rivers, coral reefs,...). Treated water is sometimes disinfected
chemically or physically (for example, by lagoons and microfiltration) prior to
discharge into a stream, river, bay, lagoon or wetland, or it can be used for
the irrigation of a golf course, green way or park. If it is sufficiently clean, it can also
be used for groundwater recharge or agricultural purposes.

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Pretreatment
Pretreatment removes all materials that can be easily collected from the raw sewage before
they damage or clog the pumps and sewage lines of primary treatment clarifiers. Objects
commonly removed during pretreatment include trash, tree limbs, leaves, branches, and other
large objects.
The influent in sewage water passes through a bar screen to remove all large objects like
cans, rags, sticks, plastic packets etc. carried in the sewage stream.[6]
This is most commonly
done with an automated mechanically raked bar screen in modern plants serving large
populations, while in smaller or less modern plants, a manually cleaned screen may be used.
The raking action of a mechanical bar screen is typically paced according to the accumulation
on the bar screens and/or flow rate. The solids are collected and later disposed in a landfill, or
incinerated. Bar screens or mesh screens of varying sizes may be used to optimize solids
removal. If gross solids are not removed, they become entrained in pipes and moving parts of
the treatment plant, and can cause substantial damage and inefficiency in the process.[7]:9
Grit removal
Grit consists of sand, gravel, cinders, and other heavy materials.[8]
It also includes organic
matter such as eggshells, bone chips, seeds, and coffee grounds.[8]
Pretreatment may include a
sand or grit channel or chamber, where the velocity of the incoming sewage is adjusted to
allow the settlement of sand and grit. Grit removal is necessary to (1) reduce formation of
heavy deposits in aeration tanks, aerobic digesters, pipelines, channels, and conduits; (2)
reduce the frequency of digester cleaning caused by excessive accumulations of grit; and (3)
protect moving mechanical equipment from abrasion and accompanying abnormal
wear.[8]
The removal of grit is essential for equipment with closely machined metal surfaces
such as comminutors, fine screens, centrifuges, heat exchangers, and high pressure diaphram
pumps.[8]
Grit chambers come in 3 types: horizontal grit chambers, aerated grit chambers and
vortex grit chambers. Vortex type grit chambers include mechanically induced vortex,
hydraulically induced vortex, and multi-tray vortex separators. Given that traditionally, grit

Page | 24
removal systems have been designed to remove clean inorganic particles that are greater than
0.210 mm, most grit passes through the grit removal flows under normal conditions.[8]
During
periods of high flow ... deposited grit is resuspended and the quantity of grit reaching the
treatment plant increases substantially.[8]
It is, therefore important that the grit removal
system not only operate efficiently during normal flow conditions but also under sustained
peak flows when the greatest volume of grit reaches the plant.[8]
Flow equalization
Clarifiers and mechanized secondary treatment are more efficient under uniform flow
conditions. Equalization basins may be used for temporary storage of diurnal or wet-weather
flow peaks. Basins provide a place to temporarily hold incoming sewage during plant
maintenance and a means of diluting and distributing batch discharges of toxic or high-
strength waste which might otherwise inhibit biological secondary treatment (including
portable toilet waste, vehicle holding tanks, and septic tank pumpers). Flow equalization
basins require variable discharge control, typically include provisions for bypass and
cleaning, and may also include aerators. Cleaning may be easier if the basin is downstream of
screening and grit removal.[9]
Fat and grease removal
In some larger plants, fat and grease are removed by passing the sewage through a small tank
where skimmers collect the fat floating on the surface. Air blowers in the base of the tank
may also be used to help recover the fat as a froth. Many plants, however, use primary
clarifiers with mechanical surface skimmers for fat and grease removal.
Primary treatment
In the primary sedimentation stage, sewage flows through large tanks, commonly called "pre-
settling basins", "primary sedimentation tanks" or "primary clarifiers".[10]
The tanks are used
to settle sludge while grease and oils rise to the surface and are skimmed off. Primary settling
tanks are usually equipped with mechanically driven scrapers that continually drive the
collected sludge towards a hopper in the base of the tank where it is pumped to sludge
treatment facilities.[7]:9–11
Grease and oil from the floating material can sometimes be
recovered for saponification (soap making).
Secondary treatment
Secondary treatment is designed to substantially degrade the biological content of the sewage
which are derived from human waste, food waste, soaps and detergent. The majority of
municipal plants treat the settled sewage liquor using aerobic biological processes. To be
effective, the biota require both oxygen and food to live. The bacteria and protozoaconsume
biodegradable soluble organic contaminants (e.g. sugars, fats, organic short-
chain carbon molecules, etc.) and bind much of the less soluble fractions into floc.
Secondary treatment systems are classified as fixed-film or suspended-growth systems.
 Fixed-film or attached growth systems include trickling filters, constructed wetlands,
bio-towers, and rotating biological contactors, where the biomass grows on media and
the sewage passes over its surface.[7]:11–13
The fixed-film principle has further
developed into Moving Bed Biofilm Reactors (MBBR)[11]
and Integrated Fixed-Film
Activated Sludge (IFAS) processes.[12]
An MBBR system typically requires a smaller
footprint than suspended-growth systems.[13]
 Suspended-growth systems include activated sludge, where the biomass is mixed with
the sewage and can be operated in a smaller space than trickling filters that treat the
same amount of water. However, fixed-film systems are more able to cope with
drastic changes in the amount of biological material and can provide higher removal
rates for organic material and suspended solids than suspended growth systems.

Page | 25
Some secondary treatment methods include a secondary clarifier to settle out and separate
biological floc or filter material grown in the secondary treatment bioreactor.
Tertiary treatment
The purpose of tertiary treatment is to provide a final treatment stage to further improve the
effluent quality before it is discharged to the receiving environment (sea, river, lake, wet
lands, ground, etc.). More than one tertiary treatment process may be used at any treatment
plant. If disinfection is practised, it is always the final process. It is also called "effluent
polishing."
Filtration
Sand filtration removes much of the residual suspended matter. Filtration over activated
carbon, also called carbon adsorption,removes residual toxins.
Nitrogen removal
Nitrogen is removed through the biological oxidation of nitrogen
from ammonia to nitrate (nitrification), followed by denitrification, the reduction of nitrate to
nitrogen gas. Nitrogen gas is released to the atmosphere and thus removed from the water.
Nitrification itself is a two-step aerobic process, each step facilitated by a different type of
bacteria. The oxidation of ammonia (NH3) to nitrite (NO2
−
) is most often facilitated
by Nitrosomonas spp. ("nitroso" referring to the formation of a nitroso functional group).
Nitrite oxidation to nitrate (NO3
−
), though traditionally believed to be facilitated
by Nitrobacterspp. (nitro referring the formation of a nitro functional group), is now known
to be facilitated in the environment almost exclusively by Nitrospira spp.
Denitrification requires anoxic conditions to encourage the appropriate biological
communities to form. It is facilitated by a wide diversity of bacteria. Sand filters, lagooning
and reed beds can all be used to reduce nitrogen, but the activated sludge process (if designed
well) can do the job the most easily. Since denitrification is the reduction of nitrate to
dinitrogen (molecular nitrogen) gas, an electron donor is needed. This can be, depending on
the waste water, organic matter (from feces), sulfide, or an added donor like methanol. The
sludge in the anoxic tanks (denitrification tanks) must be mixed well (mixture of recirculated
mixed liquor, return activated sludge [RAS], and raw influent) e.g. by using submersible
mixers in order to achieve the desired denitrification.
Sometimes the conversion of toxic ammonia to nitrate alone is referred to as tertiary
treatment.
Phosphorus removal
Every adult human excretes between 200 and 1000 grams of phosphorus annually. Studies of
United States sewage in the late 1960s estimated mean per capita contributions of 500 grams
in urine and feces, 1000 grams in synthetic detergents, and lesser variable amounts used as
corrosion and scale control chemicals in water supplies.[19]
Source control via alternative
detergent formulations has subsequently reduced the largest contribution, but the content of
urine and feces will remain unchanged. Phosphorus removal is important as it is a limiting
nutrient for algae growth in many fresh water systems. (For a description of the negative
effects of algae, see Nutrient removal). It is also particularly important for water reuse
systems where high phosphorus concentrations may lead to fouling of downstream equipment
such as reverse osmosis.
Phosphorus can be removed biologically in a process called enhanced biological phosphorus
removal. In this process, specific bacteria, called polyphosphate-accumulating
organisms (PAOs), are selectively enriched and accumulate large quantities of phosphorus
within their cells (up to 20 percent of their mass). When the biomass enriched in these
bacteria is separated from the treated water, these biosolids have a high fertilizer value.

Page | 26
Phosphorus removal can also be achieved by chemical precipitation, usually
with salts of iron (e.g. ferric chloride), aluminum (e.g. alum), or lime. This may lead to
excessive sludge production as hydroxides precipitate and the added chemicals can be
expensive. Chemical phosphorus removal requires significantly smaller equipment footprint
than biological removal, is easier to operate and is often more reliable than biological
phosphorus removal. Another method for phosphorus removal is to use granular laterite.
Once removed, phosphorus, in the form of a phosphate-rich sewage sludge, may be dumped
in a landfill or used as fertilizer. In the latter case, the treated sewage sludge is also
sometimes referred to as biosolids.
Disinfection
The purpose of disinfection in the treatment of waste water is to substantially reduce the
number of microorganisms in the water to be discharged back into the environment for the
later use of drinking, bathing, irrigation, etc. The effectiveness of disinfection depends on the
quality of the water being treated (e.g., cloudiness, pH, etc.), the type of disinfection being
used, the disinfectant dosage (concentration and time), and other environmental variables.
Cloudy water will be treated less successfully, since solid matter can shield organisms,
especially from ultraviolet light or if contact times are low. Generally, short contact times,
low doses and high flows all militate against effective disinfection. Common methods of
disinfection include ozone, chlorine, ultraviolet light, or sodium
hypochlorite.[7]:16
Chloramine, which is used for drinking water, is not used in the treatment
of waste water because of its persistence. After multiple steps of disinfection, the treated
water is ready to be released back into the water cycle by means of the nearest body of water
or agriculture. Afterwards, the water can be transferred to reserves for everyday human uses.
Chlorination remains the most common form of waste water disinfection in North
America due to its low cost and long-term history of effectiveness. One disadvantage is that
chlorination of residual organic material can generate chlorinated-organic compounds that
may be carcinogenic or harmful to the environment. Residual chlorine or chloramines may
also be capable of chlorinating organic material in the natural aquatic environment. Further,
because residual chlorine is toxic to aquatic species, the treated effluent must also be
chemically dechlorinated, adding to the complexity and cost of treatment.
Ultraviolet (UV) light can be used instead of chlorine, iodine, or other chemicals. Because no
chemicals are used, the treated water has no adverse effect on organisms that later consume
it, as may be the case with other methods. UV radiation causes damage to
the genetic structure of bacteria, viruses, and other pathogens, making them incapable of
reproduction. The key disadvantages of UV disinfection are the need for frequent lamp
maintenance and replacement and the need for a highly treated effluent to ensure that the
target microorganisms are not shielded from the UV radiation (i.e., any solids present in the
treated effluent may protect microorganisms from the UV light). In the United Kingdom, UV
light is becoming the most common means of disinfection because of the concerns about the
impacts of chlorine in chlorinating residual organics in the wastewater and in chlorinating
organics in the receiving water. Some sewage treatment systems in Canada and the US also
use UV light for their effluent water disinfection.
Ozone (O3) is generated by passing oxygen (O2) through a high voltage potential resulting in
a third oxygen atom becoming attached and forming O3. Ozone is very unstable and reactive
and oxidizes most organic material it comes in contact with, thereby destroying many
pathogenic microorganisms. Ozone is considered to be safer than chlorine because, unlike
chlorine which has to be stored on site (highly poisonous in the event of an accidental
release), ozone is generated on-site as needed. Ozonation also produces fewer disinfection

Page | 27
by-products than chlorination. A disadvantage of ozone disinfection is the high cost of the
ozone generation equipment and the requirements for special operators.
Fourth treatment stage
Micropollutants such as pharmaceuticals, ingredients of household chemicals, chemicals used
in small businesses or industries, environmental persistent pharmaceutical pollutant(EPPP) or
pesticides may not be eliminated in the conventional treatment process (primary, secondary
and tertiary treatment) and therefore lead to water pollution.[23]
Although concentrations of
those substances and their decompostion products are quite low, there is still a chance to
harm aquatic organisms. For pharmaceuticals, the following substances have been identified
as "toxicologically relevant": substances with endocrine
disrupting effects, genotoxic substances and substances that enhance the development
of bacterial resistances.[24]
They mainly belong to the group of environmental persistent
pharmaceutical pollutants. Techniques for elimination of micropollutants via a fourth
treatment stage during sewage treatment are being tested in Germany, Switzerland[citation
needed]
and the Netherlands.[25]
However, since those techniques are still costly, they are not
yet applied on a regular basis. Such process steps mainly consist of activated carbon filters
that adsorb the micropollutants. Ozone can also be applied as an oxidative method.[26]
Also
the use of enzymes such as the enzyme laccase is under investigation.[27]
A new concept
which could provide an energy-efficient treatment of micropollutants could be the use of
laccase secreting fungi cultivated at a wastewater treatment plant to degrade micropollutants
and at the same time to provide enzymes at a cathode of a microbial biofuel
cells.[28]
Microbial biofuel cells are investigated for their property to treat organic matter in
wastewater.[29]
To reduce pharmaceuticals in water bodies, also "source control" measures are under
investigation, such as innovations in drug development or more responsible handling of
drugs.[24][30]
Odor control
Odors emitted by sewage treatment are typically an indication of an anaerobic or "septic"
condition.[31]
Early stages of processing will tend to produce foul-smelling gases,
with hydrogen sulfide being most common in generating complaints. Large process plants in
urban areas will often treat the odors with carbon reactors, a contact media with bio-slimes,
small doses of chlorine, or circulating fluids to biologically capture and metabolize the
noxious gases.[32]
Other methods of odor control exist, including addition of iron
salts, hydrogen peroxide, calcium nitrate, etc. to manage hydrogen sulfide levels.
High-density solids pumps are suitable for reducing odors by conveying sludge through
hermetic closed pipework.
Energy requirements
For conventional sewage treatment plants, around 30 percent of the annual operating costs is
usually required for energy. The energy requirements vary with type of treatment process as
well as wastewater load. For example, constructed wetlands have a lower energy requirement
than activated sludge plants, as less energy is required for the aeration step Sewage treatment
plants that produce biogas in their sewage sludge treatment process with anaerobic
digestion can produce enough energy to meet most of the energy needs of the sewage
treatment plant itself.[1]:1505
In conventional secondary treatment processes, most of the electricity is used for aeration,
pumping systems and equipment for the dewatering and drying of sewage sludge. Advanced
wastewater treatment plants, e.g. for nutrient removal, require more energy than plants that
only achieve primary or secondary treatment.[1]:1704

Page | 28
Sludge treatment and disposal
The sludges accumulated in a wastewater treatment process must be treated and disposed of
in a safe and effective manner. The purpose of digestion is to reduce the amount of organic
matter and the number of disease-causing microorganisms present in the solids. The most
common treatment options include anaerobic digestion, aerobic digestion,
and composting. Incineration is also used, albeit to a much lesser degree.
Sludge treatment depends on the amount of solids generated and other site-specific
conditions. Composting is most often applied to small-scale plants with aerobic digestion for
mid-sized operations, and anaerobic digestion for the larger-scale operations.
The sludge is sometimes passed through a so-called pre-thickener which de-waters the
sludge. Types of pre-thickeners include centrifugal sludge thickeners[34]
rotary drum sludge
thickeners and belt filter presses. Dewatered sludge may be incinerated or transported offsite
for disposal in a landfill or use as an agricultural soil amendment.

Page | 29
Baggage handling system
A baggage handling system (BHS) is a type of conveyor system installed in airports that transports
checked luggage from ticket counters to areas where the bags can be loaded onto airplanes. A BHS
also transports checked baggage coming from airplanes to baggage claims or to an area where the
bag can be loaded onto another airplane.
Although the primary function of a BHS is the transportation of bags, a typical BHS will serve other
functions involved in making sure that a bag gets to the correct location in the airport. Sortation is
the process of identifying a bag and the information associated with it, to decide where the bag
should be directed within the system.
In addition to sortation, a BHS may also perform the following functions:
 Detection of bag jams
 Volume regulation (to ensure that input points are controlled to avoid overloading system)
 Load balancing (to evenly distribute bag volume between conveyor sub-systems)
 Bag counting
 Bag tracking
 Redirection of bags via pusher or diverter
 Automatic Tag Reader (ATR) (Reads the tags on the luggage provided by the airlines)
There is an entire process that the BHS controls. From the moment the bag is set on the inbound
conveyor, to the gathering conveyor, through sorting until it arrives at the designated aircraft and
onto the baggage carousel after the flight, the BHS has control over the bag

Page | 30
Many baggage handling systems offer software to better manage the system. There has also
been a breakthrough with "mobile" BHS software where managers of the system can check and
correct problems from their mobile phone.
Post September 11, 2001, majority of airports around the world began to implement baggage
screening directly into BHS. These systems are referred to as "Checked Baggage Inspection
System" by the Transportation Security Administration (TSA) in the USA, where baggage are fed
directly into Explosive Detection System (EDS) machines. A CBIS can sort baggage based on
each bag's security status assigned by an EDS machine or by a security screening operator.
CBIS design standards and guidelines are issued by the TSA once every year since 2008.
Kolkata Airport (CCU) or Netaji Subhas Chandra Bose International Airport has one unic large
Terminal which includes both domestic and international flights.
Kolkata Airport counts with 10 luggage conveyor belts for the Domestic arriving flights and 6 for the
international operations.
CCU Airport counts with 112 check-in desks within the passenger Terminal (domestic and
international operations). They are distributed (approximately) in the following way:
• Check-in Island B: operates with domestic flights. Go Air & Spice Jet
• Check-in Island C: operates with domestic flights. Indigo
• Check-in Island D: operates with domestic flights. Jet Airways
• Check-in Island E: operates with domestic flights. Air India
• Check-in Island F: operates with international flights. Air Asia, Singapore Airlines/Silk air, Thai
Airways
• Check-in Island G: operates with international flights. Air India, Biman Bangladesh, United Airways,
Bhutan Airways, China Eastern Airways
• Check-in Island H: operates with international flights. Emirates, Qatar Airways, Dragon air, Druk Air,
Regent Airways

Page | 31
In the Departures section, the baggage handling system automatically weighs, scans and sorts the
passenger baggage multiple number of times, to ensure no unethical object is taken-in by the
passengers. If any bag is scanned and found to contain something objectionable, the bag is routed
through a different way, and checked by the personnel again, in-front of the owner of the bag, and,
if possible, the bag is again returned into the baggage track, when the objectionable object is
removed.
The Arrival section also scans the bags, but, the checking process is not as intense as that of
Departures, as the bags have already been scanned and verified by the departing airport BHS. On the
passenger-side, the passenger hands-over his/her checked baggage to the airport personnel, and is
again reconciled with the bag at the arriving airport, when the bags are put on the baggage carousel.
(A baggage carousel)

Page | 32
Runway lighting system
Runway lighting
(Night runway view from A320 cockpit)
(Ground light at Bremen Airport)
Runway lighting is used at airports that allow night landings. Seen from the air, runway lights form
an outline of the runway. A runway may have some or all of the following :-
• Runway end identifier lights (REIL) – unidirectional (facing approach direction) or
omnidirectional pair of synchronized flashing lights installed at the runway threshold, one on each
side.
• Runway end lights – a pair of four lights on each side of the runway on precision instrument
runways, these lights extend along the full width of the runway. These lights show green when
viewed by approaching aircraft and red when seen from the runway.
• Runway edge lights – white elevated lights that run the length of the runway on either side.
On precision instrument runways, the edge-lighting becomes amber in the last 2,000 ft (610 m) of
the runway, or last third of the runway, whichever is less. Taxiways are differentiated by being
bordered by blue lights, or by having green centre lights, depending on the width of the taxiway, and
the complexity of the taxi pattern.
• Runway centerline lighting system (RCLS) – lights embedded into the surface of the runway
at 50 ft (15 m) intervals along the runway centerline on some precision instrument runways. White
except the last 900 m (3,000 ft): alternate white and red for next 600 m (1,969 ft) and red for last
300 m (984 ft).
• Touchdown zone lights (TDZL) – rows of white light bars (with three in each row) at 30 or 60
m (98 or 197 ft) intervals on either side of the centerline for 900 m (3,000 ft).
• Taxiway centerline lead-off lights – installed along lead-off markings, alternate green and
yellow lights embedded into the runway pavement. It starts with green light at about the runway
centerline to the position of first centerline light beyond the Hold-Short markings on the taxiway.

Page | 33
• Taxiway centerline lead-on lights – installed the same way as taxiway centerline lead-off
Lights, but directing airplane traffic in the opposite direction.
• Land and hold short lights – a row of white pulsating lights installed across the runway to
indicate hold short position on some runways that are facilitating land and hold short operations
(LAHSO).
• Approach lighting system (ALS) – a lighting system installed on the approach end of an
airport runway and consists of a series of lightbars, strobe lights, or a combination of the two that
extends outward from the runway end.
According to Transport Canada's regulations, the runway-edge lighting must be visible for at least 2
mi (3 km). Additionally, a new system of advisory lighting, runway status lights, is currently being
tested in the United States.
The edge lights must be arranged such that:
• the minimum distance between lines is 75 ft (23 m), and maximum is 200 ft (61 m);
• the maximum distance between lights within each line is 200 ft (61 m);
• the minimum length of parallel lines is 1,400 ft (427 m);
• the minimum number of lights in the line is 8.
To maintain the aircraft in glide path PAPI are used.
Precision approach path indicator
A precision approach path indicator (PAPI) is a visual aid that provides guidance information to help
a pilot acquire and maintain the correct approach (in the vertical plane) to an airport or an
aerodrome. It is generally located beside the runway approximately 300 meters beyond the landing
threshold of the runway.
The greater number of red lights visible compared with the number of white lights visible in the
picture means that the aircraft is flying below the glideslope. To use the guidance information
provided by the aid to follow the correct glide slope a pilot would manoeuvre the aircraft to obtain
an equal number of red and white lights.
Student pilots in initial training may use the mnemonic, until they are used to the lights' meaning.
• WHITE on WHITE - "Check your height" (or "You're out of sight", or "Higher than a kite") (too
high)
• RED on WHITE – "You're all right"
• RED on RED – "You're dead" (too low)

Page | 34
Individual precision approach path indicator
The PAPI is a light array positioned beside the runway. It normally consists of four equi-spaced light
units color-coded to provide a visual indication of an aircraft's position relative to the designated
glideslope for the runway. An abbreviated system consisting of two light units can be used for some
categories of aircraft operations. The international standard for PAPI is published by the
International Civil Aviation Organisation (ICAO) in Aerodromes, Annex 14 to the Convention on
International Civil Aviation, Volume 1, Chapter 5. National regulations generally adopt the standards
and recommended practices published by ICAO. An earlier glideslope indicator system, the visual
approach slope indicator (VASI) is now obsolete and was deleted from Annex 14 in 1995. The VASI
only provided guidance down to heights of 60 metres (200 ft) whereas PAPI provides guidance down
to flare initiation (typically 15 metres, or 50 ft).
The PAPI is usually located on the left-hand side of the runway at right angles to the runway center
line. The units are spaced 9 meters apart with the nearest unit 15 meters from the runway edge. A
PAPI can, if required, be located on the right-hand side of the runway. At some locations PAPIs are
installed on both sides of the runway but this level of provision is beyond the requirements of ICAO.
The light characteristics of all light units are identical. In good visibility conditions the guidance
information can be used at ranges up to 5 miles (8.0 km) by day and night. At night the light bars can
be seen at ranges of at least 20 miles (32 km).
Each light unit consists of one or more light sources, red filters and lenses. Each light unit emits a
high-intensity beam. The lower segment of the beam is red, and the upper part is white. The
transition between the two colours must take place over an angle not greater than three minutes of
arc. This characteristic makes the color change very conspicuous, a key feature of the PAPI signal. To
form the PAPI guidance signal, the color transition boundaries of the four units are fixed at different
angles. The lowest angle is used for the unit furthest from the runway, the highest for the unit
nearest to the runway. The designated glideslope is midway between the second and third light unit
settings. Depending on the position of the aircraft relative to the specified angle of approach, the
lights will appear either red or white to the pilot. The pilot will have reached the normal glidepath
(usually 3 degrees) when there is an equal number of red and white lights. If an aircraft is beneath
the glidepath, red lights will outnumber white; if an aircraft is above the glidepath, more white lights
are visible.
PAPI systems are readily available from airfield lighting manufacturers worldwide. PAPI is normally
operated by air traffic control (ATC). If ATC services are not normally provided at an aerodrome, PAPI

Page | 35
along with other airport lights may be activated by the pilot by keying the aircraft microphone with
the aircraft's communication radio tuned to the CTAF or dedicated pilot controlled lighting (PCL)
frequency.
Instrument landing system localizer
Instrument landing system localizer (short: localizer [LOC]) is a system of horizontal guidance in the
instrument landing system, which is used to guide aircraft along the axis of the runway.
Each radio station or system shall be classified by the service in which it operates permanently or
temporarily.
In aviation, a localizer is the lateral component of the instrument landing system (ILS) for the runway
centreline when combined with the vertical glide slope, not to be confused with a locator, although
both are parts of aviation navigation systems.
A localizer (like a glideslope) works as a cooperation between the transmitting airport runway and
the receiving cockpit instruments. An older aircraft without ILS receiver cannot take advantage of
any ILS facilities at any runway, and much more importantly, the most modern aircraft have no use
of their ILS instruments at runways which lack ILS facilities. In parts of Africa and Asia large airports
may lack any kind of transmitting ILS system. Some runways have ILS only in one direction, this can
however still be used (with a lower precision) known as back beam or "Back Course" which is not
associated with a glide slope.
Control of lighting system
Typically the lights are controlled by a control tower, a flight service station or another designated
authority. Some airports/airfields (particularly uncontrolled ones) are equipped with pilot-controlled
lighting, so that pilots can temporarily turn on the lights when the relevant authority is not available.
This avoids the need for automatic systems or staff to turn the lights on at night or in other low

Page | 36
visibility situations. This also avoids the cost of having the lighting system on for extended periods.
Smaller airports may not have lighted runways or runway markings. Particularly at private airfields
for light planes, there may be nothing more than a windsock beside a landing strip.
Runway lights are electrically controlled by Constant Current Regulators (CCRs), which has both
power and control lines, and are able to illuminate individual lamps with a constant current,
according to the Brightness level being set (B1-B5) or turn it ON/OFF.
Runway safety
Types of runway safety incidents include:
• Runway excursion - an incident involving only a single aircraft, where it makes an
inappropriate exit from the runway (e.g. Thai Airways Flight 679).
• Runway overrun (also known as an overshoot) - a type of excursion where the aircraft is
unable to stop before the end of the runway (e.g. Air France Flight 358, TAM Airlines 3054).
• Runway incursion - an incident involving incorrect presence of a vehicle, person or another
aircraft on the runway (e.g. Tenerife airport disaster (Pan American World Airways Flight 1736 and
KLM Flight 4805)).
• Runway confusion - an aircraft makes use of the wrong runway for landing or takeoff (e.g.
Singapore Airlines Flight 006, Western Airlines Flight 2605).
• Runway undershoot - an aircraft that lands short of the runway (e.g. British Airways Flight
38, Asiana Airlines Flight 214).
Flight rules
Flight rules may refer to:
• Instrument flight rules, regulations and procedures for flying aircraft by referring only to the
aircraft instrument panel for navigation
• Night VFR, the rules under which flight primarily by visual reference is done at night
• Special visual flight rules, a set of aviation regulations under which a pilot may operate an
aircraft
• Visual flight rules, a set of regulations which allow a pilot to operate an aircraft in weather
conditions generally clear enough to allow the pilot to see where the aircraft is going.
Visual flight rules
Visual flight rules (VFR) are a set of regulations under which a pilot operates an aircraft in weather
conditions generally clear enough to allow the pilot to see where the aircraft is going. Specifically,
the weather must be better than basic VFR weather minima, i.e. in visual meteorological conditions
(VMC), as specified in the rules of the relevant aviation authority. The pilot must be able to operate
the aircraft with visual reference to the ground, and by visually avoiding obstructions and other
aircraft.
If the weather is below VMC, pilots are required to use instrument flight rules, and operation of the
aircraft will primarily be through referencing the instruments rather than visual reference. In a
control zone, a VFR flight may obtain a clearance from air traffic control to operate as Special VFR.

Page | 37
Night VFR
Night VFR, or night visual flight rules (NVFR), are the rules under which a flight primarily by visual
reference may be performed at night. NVFR rating is compulsory for all professional pilots. In EASA
countries there are flowing requirements for passing NVFR rating training in ATO approved training
organisation:
Total of 5 hours of VFR flying at night (NVFR)
• of which there are at least 3 hours flying on dual command with instructor,
• of which there are at least 5 take-offs and landings as full stop landings at night,
• of which there is at least 1 navigational flight by visual flight rules at night on dual command
with instructor with a length of at least 50 km in duration of at least 1 hour (60 minutes) or more,
In many countries, VFR flight at night is not permitted, in which case night flying is by instrument
flight rules (IFR) only which, in almost all countries, requires an instrument rating. Exceptions include
Australia, New Zealand, Canada, Germany, Norway, Finland, France, Belgium, Luxembourg, Poland,
Serbia, Spain, South Africa, Sweden, Switzerland, the United Kingdom, and the United States.
Special visual flight rules
Special visual flight rules (Special VFR, SVFR) are a set of aviation regulations under which a pilot may
operate an aircraft. It's a special case of operating under visual flight rules(VFR).
Instrument flight rules
Instrument flight rules (IFR) is one of two sets of regulations governing all aspects of civil aviation
aircraft operations; the other is visual flight rules (VFR). When operation of an aircraft under VFR is
not safe, because the visual cues outside the aircraft are obscured by weather or darkness,
instrument flight rules must be used instead. IFR permits an aircraft to operate in instrument
meteorological conditions (IMC), which is essentially any weather condition less than VMC but in
which aircraft can still operate safely. Use of instrument flight rules is also required when flying in
"Class A" airspace regardless of weather conditions. Class A airspace extends from 18,000 feet above
mean sea level to flight level 600 (60,000 feet pressure altitude) above the contiguous 48 United
States and overlying the waters within 12 miles thereof.[8] Flight in Class A airspace requires pilots
and aircraft to be instrument equipped and rated and to be operating under Instrument Flight Rules
(IFR). In many countries commercial airliners and their pilots must operate under IFR as the majority
of flights enter Class A airspace; however, aircraft operating as commercial airliners must operate
under IFR even if the flight plan does not take the craft into Class A airspace, such as with smaller
regional flights. Procedures and training are significantly more complex compared to VFR instruction,
as a pilot must demonstrate competency in conducting an entire cross-country flight solely by
reference to instruments.
Instrument pilots must meticulously evaluate weather, create a very detailed flight plan based
around specific instrument departure, en route, and arrival procedures, and dispatch the flight.

Page | 38
Cargo handling system
The International air cargo terminal at Kolkata Airport was the first air cargo terminal in the country,
which was commissioned on 5th October, 1975. The international air cargo complex is located 1/2
km north of international terminal building with well-connected road infrastructure for smooth
functioning of air cargo services. The total covered area of air cargo terminal is 21,906 square meter
and its annual holding capacity including trans-shipment is 120000 MT. as of 1/4/13. There are four
parking bays exclusively for freighter fleet, which can accommodate up to B-747 type of aircraft. AAI
has created this air cargo terminal with various facilities for processing air cargo in the terminal
building at par with any international airport. All operating airlines and other agencies, which are
connected with the clearance and pre-shipment formalities, have been accommodated under one
roof at air cargo complex. AAI was appointed as a Custodian of Import and Export cargo as per
Custom notification 2/78 under section of 45 of Customs Act, 1962. Most of the regulatory and
facilitation were established under one roof. The cargo terminal has three wings for processing of
Export, Import cargo and Unaccompanied Baggage (Import) besides Disposal Unit for disposal of
unclaimed / uncleared cargo. Kolkata International Air Cargo Terminal provides air cargo services to
entire Eastern and Northern-Eastern region for trans-shipment cargo. In international freight
transactions it connects six regions in the world, which are enriched in global market - South-Asian,
South-East Asian Countries, Western Countries, Middle-East Countries, Central Asia.
CLEARANCE PROCEDURE & PRE SHIPMENT PROCEDURE FOR EXPORT BAGGAGE:
1. Obtain carting order Baggage Declaration form from airlines or through EDI LOCATION -
Respective Airline Offices
2. Obtain T C receipt from AAI counter and pay in the bank or by cash LOCATION - AAI TC
Counter, Export Wing, State Bank of India
3. Registerd BD form with Customs LOCATION - Customs Hall (BD Unit)
4. Present BD Form to customs along with baggage, complete the customs examination and
obtain "Let Export" order.
5. LOCATION - Customs Hall
6. Handover the documents to concerned airlines
7. LOCATION - Respective Airline Offices
8. Cargo is unitized by individual airlines as per loading instructions.
9. LOCATION - AAI Export Palletisation Area
10. Release of Export cargo from cargo terminal by individual airlines after permission from
export freight officer (EFO) of Customs
11. LOCATION - AAI Palletisation Area, Export Wing
PRE SHIPMENT PROCEDURE FOR EXPORT GENERAL CARGO:
1. Registration, Processing of pre-shipping bill by customs (CRU) LOCATION -Customs Hall
2. Obtain carting order and AWB from the carreir / IATA agent or through EDI LOCATION -
Respective Airline Offices / IATA Agent
3. Present documents / shipping bill / AWB / Carting order / to AAI counter and obtain terminal
charges receipt or all through web based EDI system. LOCATION - AAI TC Counter - Export
Wing
4. Present shipping bill / AWB / Carting order / Terminal charges receipt to AAI staff
LOCATION - Truck Dock Area
Complete customs examination and obtain "Let Export Order" from customs
LOCATION - Export Examination Area

Page | 39
5. Handover complete bunch of documents (AWB / Shipping Bill / TC) to concerned airlines
LOCATION -Respective airlines offices at 3rd floor / Airlines pigeonhole almirah, positioned
at Export exit gate of export bonded area near exit gate.
6. Release of cargo to the airlines and presenting of export manifest after collecting Demurrage
charges etc. LOCATION - Exit gate, Export Wing
7. Unitization by individual airlines LOCATION - AAI Export Palletisation
8. Release of export cargo for the flight with customs approval LOCATION - AAI Export
Palletisation area
CLEARANCE PROCEDURE OF IMPORT BAGGAGE:
1. Obtain delivery order from the concerned airline, break bulk agent. LOCATION - Respective
airline / Break Bulk Agent
2. File Baggage Declaration Form (BD) with customs along with airway bill / delivery order.
LOCATION – Customs BD unit in Customs Hall.
3. Obtain TSP receipt (Location-cum-Bank Challan- LSBC) from AAI which indicates no. of pkgs
to be examined in the location. LOCATION - Import Wing
4. Obtain packages required for customs examinations / forwarding AAI Staff. LOCATION -
Examination / Delivery counter - Import Wing, 1000 hrs - 1600 hrs
5. Complete customs examination of the packages and get them repacked in presence of CHA /
by designated customs officer or PAX. LOCATION - Customs examination hall
6. Payment of Customs Duty amount and AAI charges in Bank. LOCATION - State Bank of India,
2nd floor, Administrative Building
7. Deposit AAI Charges in bank or by cash. LOCATION - SBI counter, 2nd floor, Administrative
Building
8. Obtain Gate pass against AAI charges payment receipt LOCATION - Computer Counter,
Import Wing, 1000 hrs - 1800 hrs
9. Present gate pass to AAI staff for delivery of the packages LOCATION - Import Wing, Delivery
gate.
10. Take delivery from AAI staff against the original gate pass, duly endorsed by Customs Officer
at the Delivery Gate LOCATION - Delivery gate, Import
CLEARANCE PROCEDURE FOR IMPORT GENERAL CARGO
1. Obtain Delivery order from the concerned airlines or Consol Agent. LOCATION - Respective
Airlines at cargo terminal/Agent premises
2. Submit Bill of Entry along with Delivery order, letter of authority, airway bill, invoice, packing
list & import license etc. to the customs file through EDI. LOCATION - Customs Hall
3. Examination order from customs appraiser LOCATION - Customs appraiser's room
4. Obtain TSP Receipt (LSBC) from AAI counter which indicates no. of pkgs to be examined
LOCATION - Computer counter - Import wing
5. Obtain the packages for customs examination from AAI LOCATION - Location counter,
Import Wing, 1000 hrs - 1800 hrs
6. Complete customs examination by customs examiners and get it repacked. LOCATION -
Customs examination hall
7. Payment of Customs Duty in SBI and payment of AAI charges through Pre-Deposit account
maintained with AAI or in bank. LOCATION - 2nd Floor, Admn. Bldg.
8. Obtain out of charge (OOC) order from concerned customs office against Duty payment
receipt. LOCATION - Customs appraiser office
9. Obtain AAI gate pass on surrendering all documents LOCATION - Computer counter - Import
wing, 1000 hrs - 2000 hrs. Present gate pass at import wing, endorsed by customs officer at
delivery gate and obtain delivery.

Page | 40
SALIENT FEATURES
EXPORT WING
Covered Area 8,516 Sq. m
E.T.V. area 1,333 sqm
One time holding capacity 258 M.T.
Annual holding capacity 47,089 M.T.
Cargo Apron Capacity 2B-737 type & 2B-747 type
EXPORT WING
Import 13,390
Sq.m
Automated & Retrieval System (AS/RS) 1930 Sqm Storage
One time holding capacity 513 M.T
Annual holding capacity 86748 M.T.
Transhipment Area 80 Sq.m
7 Hazardous cargo shed 82 Sq.m
FACILITIES :

Page | 41
GENERAL FACILITIES :
1. On-line Integrated Cargo Management System (ICMS) for data processing
2. Forklifts
3. High Reach takers
4. Electronic/Mechanical weighing machines
5. Cargo trolleys
6. Power pallet trucks
7. Idle ULD Parking area
8. Truck-dock - 16 Nos.
9. Auction hall for disposal of unclaimed cargo
FACILITIES FOR SPECIAL CARGO:
1. Automated Storage & Retrieval System in Import
2. Elevated Transfer Vehicle in Export
3. Strong room for valuable cargo
4. Cold Storage Facilities
5. Hazardous Cargo Shed
6. Transshipment shed
PERISHABLE CARGO PERISHABLE CARGO (CPC)
Cold Storage Total area
with 3
chambers
43.80 Sq.m
Description Temperature Door Size
Chamber - A (Drug) +2° C to 4° C 2 x 1.15 Mts.
Chamber - B +2° C to 5° C
(Veg. & Fruits) 2 x 1.15 Mts.
Chamber - C (Meat) -22° C 2 x 1.15 Mts.
The entire cargo handling procedure is fully automated by rollers that are communicated via the
consignment number of the object it is handling.
ETV
Specifically designed for the efficient Storage and Retrieval of ULDs and Air Cargo Pallets. The ETV
functions are to store all types of ULDs and Pallets on multiple levels using friction driven or
motorised roller decks with a capacity of up to 14,000 kg.

Page | 42
The storage, transfer, sorting and retrieval of cargo between the warehouse and the airside is fully
automated with interfaces to the airline and WMS.
All vehicle movements are guided by the Inventory Control System with a possibility of operator
override manual mode. The ETV is built on a central rail system between the high-bay storage aisles,
with a lifting platform designed for 10, 15 and 20ft powered roller decks with an operator cabin.
ULD High Bay Storage
The ULD Storage consisting of Friction and Power driven roller decks offers a dense storage facility
for ULDs and Pallets from 5 to 20 ft. The storage and retrieval of cargo is fully automated by the ETV.
The levels can be dependent on the building allowed height and include safety fencing and fire
protection sprinkler system.
Truck Docks
Heavy Duty equipment for the transfer of ULDs to and from the warehouse and provide the vertical
alignment between the roller bed trucks and the warehouse equipment (Slave Pallets and Roller
Decks).
Available Options: stationary or mobile with 10, 15 and 20 ft driven roller decks, Weighing Scales (10
and 20 ft); Side shift; Ram Protections; Winch.
The Truck Dock interfaces with the warehouse roller decks and slave pallets for the receiving of
goods to and from the roller bed trucks. The main functionality is the immediate offloading of built-
up ULDs from the trucks and vice versa.
Interfacing the TD to the WMS & IT system ensures the full transparency of the cargo flow to and
from the warehouse.

Page | 43
High Bay Warehousing (ASRS)
ALS Automated Storage and Retrieval Systems (ASRS) are designed for the computerised storage and
retrieval of goods in the manufacturing, stock-keeping and distribution facilities where space is
scarce and efficiency and high throughput are a must.
The ASRS concept is the equivalent to high density storage of palletised cargo by means of a high
level of automation and efficiency; whether for mini load shipments or high bay pallet storage
systems.
Tote / Box Storage System
The Mini Load is a high-density tote or box buffer designed to maximize vertical storage space while
maintaining a compact footprint. A high-speed Storage/Retrieval (S/R) machine or Shuttle System
that move loads safely and accurately to support the high-volume order picking operations. Multiple
input/output and integration options are available to streamline material flow.

Page | 44
Donkey (Pallet Transporter) & Slave Pallets
Mobile vehicles to handle Slave Pallets allowing multiple mobile workstations with the aim of
providing maximum flexibility and safe handling of cargo pallets inside the warehouse. The battery-
driven transporter ensures continuous shifts as well as safe and pollution-free working environment
for the warehouse staff.
The flexible handling of ULDs and Cargo Pallets inside a warehouse requires the use of Slave Pallets.
Slave Pallets serve as mobile workstation for the efficient storage and, build-up, break-down and
avoiding cargo damage. According to the customers’ requirements, the units may be delivered with
full walkways, Narrow or Wide edge orientation and with 208 or 508 mm transfer level.

Page | 45
Conclusion
We would like to say that this training program was an excellent opportunity for us to get to
the ground level and experience the things that we would have never gained through going
straight into a job. We are grateful to Airports Authority of India for giving us this wonderful
opportunity.
The main objective of the industrial training is to provide an opportunity to undergraduates to
identify, observe and practice how engineering is applicable in the real industry. It is not only
to get experience on technical practices but also to observe live equipment and to interact
with the staff of AAI. It is easy to work with people, but not with sophisticated machines. The
only chance that an undergraduate has to have this experience is the industrial training period.
I feel I got the maximum out of that experience. Also we learnt the way of work in an
organization, the importance of being punctual, the importance of maximum commitment,
and the importance of team spirit.

Page | 46
Bibliography
 Training data provided to us from AAI, NSCBI.
 https://en.wikipedia.org
 https://www.aai.aero/

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