Management of Airport Electronics Facilities

ZULFIQAR ALI MIRANI

Info: [email protected]

Management of Airport Electronics Facilities

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1 Maintenance Management

1.1 Functions of the Technical Management 1.2 Maintenance Management – Definition 1.3 Responsibilities of Airport Electronic Maintenance (AEM)

Section 1.4 Types of Maintenance 1.5 Maintenance Methods and Practices 1.6 Aviation Electronics Engineering Facilities 1.7 Electromagnetic Compatibility (EMC) 1.8 Airport Electronics Maintenance Organization

2 Airport Terminal Electronics Facilities

2.1 Flight Information systems 2.2 Public Address System 2.3 Telecommunication Facilities 2.4 Terminal Building Automated Systems 2.5 Computer and Internet Facilities

3 Aeronautical Communication Systems

3.1 Communication system 3.2 Aeronautical Communication Services 3.3 Digital Data Communication Systems 3.4 Voice Communication Systems 3.5 Aeronautical Communication Facilities in Pakistan

4 Radio Navigation

4.1 Navigation 4.2 General Provisions for Radio Navigation Aids 4.3 Non Directional Beacon (NDB) 4.4 VHF Omni-directional Radio Range (V.O.R) 4.5 Distance Measuring Equipment (DME) 4.6 LORAN-C

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4.7 Instrument Landing System (ILS) 4.8 Microwave Landing System (MLS) 4.9 Ground Radio Navigation Facilities in Pakistan 4.10 Provision of information on the operational status of

radio navigation aids 4.11 Secondary power supply for radio navigation aids and

communication systems

5 Radar

5.1 Introduction 5.2 Primary Radar 5.3 Secondary Radar 5.4 Radar Display System 5.5 Radar System of Pakistan CAA 5.6 Radar Communication

1. MAINTENANCE MANAGEMENT 1.1. Functions of the Technical Management The Technical Management is

to associate the end user, the head of maintenance and the supplier; to forecast, plan and execute all operations to avoid the breakdown

(However breakdown is always possible); to train the personnel in the new methods, increasing their

competence and work satisfaction, associated to operation and maintenance;

to reorganize the unit (corporation or company) around the new methods;

to provide a follow-up system to measure the effect of the actions carried out by various functionaries; and

to perform all jobs related to operation, up-keeping and maintenance of engineering equipment.

In addition, the technical managers should be capable of using new solutions of the problems. To do this they must keep themselves informed of current research results of maintenance methods and techniques and latest technological development. In order to ensure cost effective maintenance of the facilities and to perform above functions, Technical Management should have the know-how of the following.

List the requirements of all the sections concerned Carry out preliminary review in accordance with these requirements Prepare specifications including documents for operational sections

and maintenance department Issue quotation requests to suppliers and analyze the offers

received Involve concerned sections, including users and maintenance

personnel, in negotiation phase and subsequently testing of the required items

Initiate training courses (if required)

“Repair” serves no purpose, it is “on time maintenance” that is really required.

Maintenance Management 1-2

1.2. Maintenance Management Historically the term “up-keep” was used in the sense to prevent breakdowns and for ensuring smooth operation of a system. There was a concept of “repair” in fashion to recover the breakdowns occurred in a system. These both concepts have been replaced by much wider concept of “maintenance”. The “maintenance” process is applied without waiting for a breakdown to occur and then repair it. The “maintenance” is a dynamic approach to prevent from mal-functioning and breakdowns. According to this new concept disturbances can be minimized through a proper planning, application of proper methods and taking precautions in time. The man and machine have to work together for achieving common goals of productivity and quality of service. The pace of advancement of technology nowadays is much greater as compared to time before invention and involvement of computer technology. The effects of technology on productivity and quality of services are also required to be taken in account. There is also need of acquiring of new technology appropriate to the genuine requirement of the organization, at appropriate time and training of the manpower accordingly. The optimization of maintenance cost is yet another factor needing due importance. The application of concepts of Health, Safety and Environment in maintenance organization is required according to local laws and regulations. The “maintenance management” deals all such functions as mentioned above and many new tasks that may arise from time to time. 1.3 Responsibilities of Airport Electronic Maintenance (AEM) Section The main objectives of AEM Section are:

User satisfaction Personnel satisfaction Owner satisfaction

The Airport Electronics Maintenance section is responsible for all equipment concerning the air safety and every thing involved in ensuring the arrival of passengers and freight to their destination. Accordingly, the AEM section is to

ensure continual satisfactory working of all equipment under their responsibility, 24 hours per day, 7 days per week.

maintain the Quality of Service and Equipment up to required standards

research optimum cost consider personnel safety and working conditions respect environmental limits

Management of Airport Electronics Facilities 1-3

“It is responsibility of the maintenance to initiate actions against pollution and other harmful effects of technical services and

installations” 1.4 Types of Maintenance

Preventive Maintenance Corrective Maintenance

Preventive Maintenance Preventive Maintenance is required to diminish the probability of breakdown according to predetermined criteria:

In function to a timetable (periodic maintenance) In function to specific items of control indicating degree of wear

It also includes partial or general up-grading according to means allowed, modification, renovation and reconstruction. Corrective Maintenance Corrective Maintenance is required to be performed randomly following a breakdown in the system. It also includes running repairs Maintenance Environment Maintenance can not be considered without taking into account the surroundings in which it functions. This new concept of “maintenance” is very much attached to the other activities of the organization, for instance, purchasing and stock of items required etc. 1.5 Maintenance Methods and Practices Maintenance method is derived from the two basic concepts i,e “preventive maintenance” and “corrective maintenance”. It includes “Work Preparation” that means to plan, define and execute the specific conditions in which the work must be done. Before starting an action one must know: WHAT must be done WHO will do it WHERE will it be done WHEN will it be done HOW it will be done HOW MANY it will need or use


In order to attain maintenance objectives, certain methods and practices are to be followed which include: Technical Documentation and methods Planning Sub-contracting Spare part stocks

Technical documentation includes General Documentation Inventory of equipment; which may further be divided into two groups

Inventory of “fixed equipment” and “mobile equipment” Material documentation; such as identity of material etc Historical documentation; such as modifications carried out, work orders,

reports of examinations and incidents, date of execution etc The Planning function in maintenance includes “General Planning” for major undertakings and “Job Planning” for current tasks. The sub-contracting can apply for reasons of profitability, when a short term supplementary demand occurs. For user company, the use of external companies depends on social, economic or strategic reasons. The stock of spares is extremely important as it may result in lack of efficiency and non-optimization of resources including economic consequences.

“To obtain optimum results, one must have precise information” 1.6 Aviation Electronics Engineering Facilities Aviation Electronics Engineering facilities can be classified as Airport Terminal Electronics Facilities Aeronautical Communication Systems Radio Navigation Radar

Note: These facilities are discussed in subsequent section.

1.7 Electromagnetic Compatibility (EMC)

Electromagnetic compatibility (EMC) has emerged as a new branch of engineering concerned with the increasing problems of radio frequency interference (RFI) and the overcrowding of the radio frequency spectrum. The EMC problem is increasing so rapidly that considerable engineering efforts are included in the design, development, RFI testing and production of all new electronic equipment from the electric razor and


TV set to the most sophisticated of electronic equipment, such as computer and radar systems. The problems are compounded not only because the frequency spectrum is overcrowded, but much earlier generation equipment, which is more susceptible to and is a more likely source of interference, is not made obsolete or scrapped. New generation equipment is potentially capable of interaction problems among themselves, as well as playing havoc with older equipment. Each year sees new users bringing new equipment into the frequency spectrum.

Electromagnetic Compatibility (EMC) essentially ensures proper working of an electrical (or electronic) system when it is placed in an electromagnetic environment shared by other electrical (or electronic) systems. This means that conducted or radiated emissions from an electrical (or electronic) system are kept within specified limits so that they may not degrade the performance of any other electrical (or electronic) system placed in the same environment. In addition to this, the electrical (or electronic) system must immune enough to the conducted or radiated emissions generated by other electrical (or electronic) systems. Electromagnetic Interference (EMI) Electromagnetic interference (or Radio Frequency Interference – RFI) consists of any unwanted, spurious, conducted and /or radiated signal of electrical origin that can cause unacceptable degradation of system or an equipment performance. The effects of EMI can range from minor nuisance to catastrophic consequences. Appearance of ghosts or snow on TV screen, cross talk in telephones, buzzing of a car radio while driving under a high tension transmission line are examples of minor nuisance. EMI can also lead to serious consequences, such as, malfunctioning of medical equipments while monitoring condition of patients, radio interference in aircrafts communication system, firing of missile due un-warranted activation of its explosive device etc. Basic elements of an EMI situation There are three essential elements of an EMI situation; they are:

a) EMI sources b) EMI receptors c) Coupling paths.

Source of EMI Any device or apparatus that transmits, distributes, processes, or otherwise utilizes any form of electrical energy can be a source of EMI. Sources of EMI can be classified as:

a) conducted or radiated, b) natural or man made, and c) intentional or unintentional


EMI signals, those conducted via electrical conducting paths are wires and ground planes, whereas radiated EMI signals have the form of electromagnetic waves transmitted through free space from source to receptor. Natural EMI sources are those associated with natural phenomenon like lighting, radiation from galactic and cosmic sources, whereas man-made sources include all electrical systems like electronic communication, power lines etc. Electrical systems whose primary function depends upon radiated emissions are called intentional radiators (for example: communication , navigation and radar system) where as unintentional radiators are those systems which radiate radio frequency signals but whose primary function is not to generate these signals.

EMI Receptors The term receptor refers to the generic class of devices, equipment and/ or system that, when exposed to EMI, either malfunction or degrade performance. These EMI receptors may be natural or man-made. Natural receptors include humans, animals & plants. Intense EM fields can damage the organic molecules of the body by heating. All electrical systems are example of man made receptors. Coupling paths There are four type of coupling paths which exist between an emitter and a receptor, which are:

a) Common Impedance Coupling b) Capacitive Coupling c) Inductive Coupling d) Radiation Coupling

Types of external EMI In practical systems electrical (or electronic) signals may be affected by a number of forms of interference. These interferences are due to the entrance of unwanted signals from the unrelated electrical (or electronic) circuits and fields into other electrical (or electronic) systems present within their effective range (that is different from device to device). Protection of systems from such interference is called screening. The major types of external interference signals are:

a) Capacitive (or electrical coupled) interference b) Inductive (or magnetically coupled) interference c) Electromagnetic interference (radiation coupling) d) Conductively coupled interference e) Ground loop interference


1.8 Airport Electronics Maintenance Organization Typical organization of an airport electronics maintenance set-up is illustrated in figure 1.8-1.

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2. AIRPORT TERMINAL ELECTRONICS FACILITIES

Airport Terminal Electronics Facilities, includes

Flight Information Systems Public Address System Telecommunication Facilities Terminal Building Automated Systems Computer and Internet Facilities

2.1 Flight Information systems Objective of FIS is to provide flight information to Passengers. It includes

Flight inquiry Flight Information Display System (FIDS) Passenger check-in counters

Flight inquiry systems are meant for providing information to outside the terminal premises. These systems include telephone inquiry system, recording etc which are in use at many airports. Use of computer and internet is becoming popular for this purpose. The modern flight inquiry systems involve computer to provide flight information. The interactive websites, updated in real time, are also there to provide latest information of flight movements. Flight Information Display System (FIDS) include flight information (electronic) display boards and monitors placed at appropriate locations from entrée to exist points for departing and arriving passengers, such as concourse hall, briefing area, lounges, gates, baggage claim area etc. Passenger check-in counters include electronic weighing scales. There are flight information boards to provide guidance and current status of flight being checked-in. The counter system is, most of the time, part of FIDS in modern systems. 2.2 Public Address (Paging) System The purpose of public address system is to deliver various type of notices and information to the passengers, airport functionaries and general public. These systems include loud speakers grouped according to area of operation such as domestic and international departures, domestic and international arrivals and concourse hall. These systems are nowadays called paging system, in which all or one or more specific area is segregated and addressed.

Airport Terminal Electronics Facilities

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2.3 Telecommunication Facilities These facilities include Direct Speech Circuits, PSTN (Public Switching Telephone Network) within airport premises, EPABX (Electronic Private Automatic Branch Exchange) and other Telephone & Telegraph services, Fax, Data Networks, TV & Entertainment Network. 2.4 Terminal Building Automated Systems These services include operation and maintenance of building automation systems including automated security system, automatic fire detection system, automatic control of water, entrée and exit gates, elevators & lifts, Intercommunication system etc. 2.5 Computer and Internet Facilities The development and maintenance of data network to support computer networks within airport premises, provision of internet facility to passenger and possibly various functionaries of airport. Provision of internet (at the airport terminal and in lounges) has become almost an essential facility. Wireless internet connection is being provided within lounges where a passenger just opens his/her laptop or palmtop computer to connect to the internet. The involvement of computers is in every function of the airport. All the sections such as Human Resource (Admin), Finance and Accounts, ATS, Tech Services, Supply and Store, Janitorial Services need computers to assist them in many functions. Most of the operational systems mentioned above involve computer as a core equipment. The provision of computer systems to the requirement of each functionary and their up-keeping and maintenance is equally important.

3. AERONAUTICAL COMMUNICATION SYSTEMS

3.1 Communication system Communication system deals with the production, transport and delivery of information (or intelligence) from source to destination. A basic communication system includes a source (of information), a transmission medium (for transportation) and destination, as shown in the figure below.

Figure 3-1.1: Basic communication system Source converts human intelligence into electrical signals; Transmission medium is responsible to carry this information to destination where it is reproduced into its original form. The information may be voice or data, transmission media may be a single channel or network or multiple networks. Transmission Media There are a number of options from which we can choose a transmission medium. The transmission mediums cane be broadly classified in the following two categories.

a) Guided or Conducted Transmission Media b) Un-guided or Radiated Transmission Media

Guided media transmission

In guided media signal is guided or directed through a channel (called conductor). In other words it is the medium that guides the signal to the destination. Some examples of guided media are:

Twisted Pair

Unshielded Twisted Pair

Shielded Twisted Pair Coaxial cable Optical Fiber Un-guided or Radiated media Such mediums do not make use of conductors; rather, the signal radiates through space between transmitter and receiver. Some examples of radiated media are: HF/VHF/UHF Radio systems Microwaves Satellite infrared

Aeronautical Communication Systems

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3.2 Aeronautical Communication Services The international aeronautical communication services are classified, by ICAO, as under: Aeronautical Fixed Service Aeronautical Mobile Service Aeronautical Radio Navigation Service Aeronautical Broadcasting Service

3.2.1 Aeronautical Fixed Service (AFS) The aeronautical fixed service comprises all types and systems of point-to-point communications in the international aeronautical telecommunication service. It includes voice and data links.

3.2.2 Aeronautical Mobile Service (AMS) AMS is a telecommunication service where one or both end users are mobile stations. Radio link is used for carrying information (commonly in the form of voice) between the two end users. HF, VHF and UHF radio communication is found most suitable for voice communication between such stations.

Figure 3.2-1: Aeronautical Mobile Communication Service Recently, ICAO has approved standards for data communication for the purpose of AMS, which is in process of implementation. The data or digital communication link, so established, between controller and pilot is given name as CPDLC or Controller-Pilot Digital Link Communication. Categories of messages: The categories of messages handled by the aeronautical mobile service are as given below. a) Distress calls, distress messages and distress traffic


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b) Urgency messages, including messages preceded by the medical transports signal c) Communications relating to direction finding d) Flight safety messages e) Meteorological messages f) Flight regularity messages

3.2.3 Aeronautical Radio Navigation Service The aeronautical radio navigation service comprises all types and systems of radio navigation aids in the international aeronautical service. Note: This topic is discussed in chapter 4. 3.2.4 Aeronautical Broadcasting Service Aeronautical broadcasts are made on specified frequencies and at specified times. Schedules and frequencies of all broadcasts are to be publicized in appropriate documents. ICAO requires publicizing of any change in frequencies or times of broadcasts at least two weeks in advance of the change. Such type of services includes automatic terminal information service (ATIS) etc. 3.3 Digital/Data Communication Systems Data link is to provide communication link for exchange of aeronautical messages in the form of data. Aeronautical Fixed Telecommunication Network (AFTN) is one of such systems being used for aeronautical data communication purpose. 3.3.1 Aeronautical Fixed Telecommunication Network (AFTN) AFTN is a global data communication network used to exchange data between various segments of air traffic services. Standard telecommunication links and protocols are used between two end users by mutual agreement. Type and priority of messages to be exchanged are standardized by ICAO. Categories of messages handled by AFTN The following categories of message are handled by the aeronautical fixed telecommunication network: a) distress messages; b) urgency messages; c) flight safety messages; d) meteorological messages; e) flight regularity messages; f) aeronautical information services (AIS) messages; g) aeronautical administrative messages; and h) service messages. 3.4 Voice Communication Systems

Aeronautical Communication Systems

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Most commonly hotline or intercom is used for voice communication between two points, e.g between two ATS units or between various sectors within an ATS unit. The figure 3.4-1 shows inter linking of two operational points within an ATS unit or in between two ATS units, for voice communication purpose.

Figure 3.4-1: Voice Communication between ground Air Traffic Services 3.5 Aeronautical Communication Facilities in Pakistan There are two types of links used for communication purpose between two airports, two ATS or Comm Ops units, depending upon the nature of information to be exchanged. They are:

Voice link Digital link

Voice Link a) Air-Ground voice communication For air-ground voice communication VHF radio link is used for civil air traffic; whereas UHF radio link is used for military aircrafts. In addition, HF radio link is used for long distance air-ground voice communication. b) Ground-to-ground voice communication Ground-to-ground voice communication is established through ground telecom network such as

hotline intercom PSTN telephone


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HF radio link is used for remote locations where ground telecom facility is not available. FM radio communication is also used, at some locations, to facilitate communication between two ATS units such as JIAP – Masroor Airbase in Karachi and AIIP – Walton airport in Lahore. Digital Link Digital link is used in for the exchange of information in the form of data between two ATS/Comm Ops units or airports. For instance, exchange of data between two locations having AMSS terminals is facilitated through digital link. Radar data of remote radar sensors (SSR stations) is transported to ACC (area control centers) at Karachi and Lahore through digital link. Technology involved in remote communication links PSTN (PTCL) network1 is mainly used for ground-to-ground voice (e.g hotline) and data (e.g AMSS) links. However satellite (V-SAT) link is used in many cases for voice and digital links. In radar, satellite is used as the main link between two remote stations supported by PSTN digital network as a back-up. Satellite link is also used for connecting the ATC operator position to the remote relay/receiver stations in Radar extended VHF communication system. Automatic Message Switching System (AMSS) AMSS is a system that facilitates exchange of digital information. The facility is provided at following locations:

Faisalabad Airport Hyderabad (CATI/Airport) Islamabad Airport Karachi ACC Karachi EED Karachi HQCAA Karachi IOU Reports

Karachi JAIP Karachi MET Lahore ACC Lahore AIIP Multan Airport Peshawar Airport Quetta Airport

AMSS system is linked with international circuits (AFTN networks) listed below.

Beijing Delhi Kabul Kuwait Mumbai Muscat Tehran

1 PSTN network is mix of sub-networks such as cable network, microwave, fiber optical network, radio links etc.

4. RADIO NAVIGATION

4.1 Navigation Navigation can simply be described as getting from one point to another point in the least possible time without losing the way. Navigation systems are the basis for an aircraft's ability to get from one place to another and know where it is and what course to follow. It's more than just maps. Radio navigation systems provide the pilot with position information from ground stations located worldwide. There are several systems offering various levels of capability and features such as course correction information, direction finding and distance measuring. Most aircraft now are equipped with some type of radio navigation equipment. Almost all flights use radio navigation equipment in some way as a primary or secondary navigation aid. Bearing Bearing of an object, in navigation, can be defined in two ways. Relative Bearing is the angle formed by the line drawn through the center line of the aircraft and a line drawn from the aircraft to the radio station. Magnetic Bearing is the angle formed by a line drawn from aircraft to the radio station and a line drawn from the aircraft to magnetic north (Bearing to station).

Figure 4.1-1: Magnetic and Relative Bearing Magnetic Bearing, here, is sum of the Magnetic Heading + Relative Bearing.

Radio Navigation

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4.2 General Provisions for Radio Navigation Aids There are different types of radio aids provided for air navigation. ICAO has classified such aids as: a) Aids to approach, landing and departure b) Short-distance aids c) Radio beacons d) Long-distance aids e) Distance measuring aids For the purpose of our convenience radio navigation aids can, broadly, be categorized as: 1. En-route Navigation Aids, which include

Non Directional Beacon (NDB or Radio Beacon)

VHF Omni-directional Radio Range (VOR)

Distance Measuring Equipment (DME)

LORAN-C 2. Aids to Approach, Landing and Departure, which include

Instrument Landing System (ILS)

Microwave Landing System (MLS)

4.3 Non Directional Beacon (NDB)

NDB or Radio Beacon (as being called alternatively) is used with direction finding equipment in the aircraft to provide bearing information of a location on the air route or of an airport. The equipment is installed en-route areas as well as on the airports to provide navigational guidance to the pilot. NDB (with rated coverage of less than 50 NM) can also be used as holding, approach and landing aid.

Figure 4.3 -1: A picture of ADF


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It radiates radio energy of a non-directional pattern permitting reception from any point within service range of the facility (usually 200 NM). Airborne equipments that interacts with NDB (ground station) is called Automatic Direction Finder (A.D.F) and indicates bearing of the NDB relay station with respect to aircraft heading (nose). ADF indicates bearing in range of 360 degree radial. Figure 4.3 -1 shows a picture of an ADF indicator.

4.4 VHF Omni-directional Radio Range (V.O.R)

The VOR is a radio aid usually located at airfields and at key locations on the air route in order to define the air routes [airways]. It provides azimuth, the course and TO-FROM information to the aircraft. AZIMUTH in VOR is a clockwise angle between magnetic north and the line connecting the VOR and the aircraft. The COURSE is the information whether aircraft is flying to the left or right of, or exactly on the pre-selected course line. TO-FROM indication tells the pilot whether an aircraft is approaching to or moving away from VOR station, with respect to the selected radial. The site of the VOR should be on the highest ground in the vicinity to obtain the greatest line-of-sight coverage. Indication of VOR information is given on airborne indicator called 'Omni Bearing Indicator’ or OBI.

Figure4.4-1: Pictures of two VOR Airborne Indicators

A basic Omni Bearing Indicator, as shown in figure 4.4-1, has a manually operated radial or 'omni Bearing Selector [OBS] which rotates an azimuth ring marked from 0° to 355°. The OBS selected radial – is indicated by the arrow at the top and the reciprocal bearing is indicated by the bottom arrow. The other features of a basic OBI are the TO-FROM indicators, a deviation bar, a deviation indicator needle and a NAV / OFF alarm flag. There are two types of VOR systems in use.

Radio Navigation

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Conventional VOR (CVOR); and Doppler VOR (DVOR).

Considering the inherent advantages and limitations, DVOR is installed in the hilly areas whereas CVOR is used in plain surfaces.

4.5 Distance Measuring Equipment (DME) The DME system is to provide the aircraft, indication of the slant range distance (expressed in nautical miles) from a ground reference point (i,e ground DME facility usually associated with VOR). The system consists of two basic components, one fitted into the aircraft and the other installed on the ground. The aircraft equipment is referred to as INTRROGATOR and the ground component as TRANSPONDER. The ground transponder equipment should be capable of handling 100 aircrafts or peak traffic which ever is less. The facility provides coverage up to 200 NM.

4.6 LORAN-C

LORAN-C is a long range navigational aid, mainly used in the regions like oceans. It determines present position by the intersection of Lines of Position (LOPs) that are hyperbolic curves. At least three stations, (a Master and two Secondaries) are needed. Accuracy is plus or minus 2.5 miles. The LORAN-C uses triangulation to measure the location of an aircraft or boat.


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4.7 Instrument Landing System (ILS) ILS is a radio aid to the final approach and is used only within a short distance from the airport. Its purpose is to help the pilot land the airplane. It is very helpful when visibility is limited. ILS facilities are highly accurate and dependable means of navigating to the runway in IFR (Instrument Flight Rules) conditions. The ILS provides the lateral and vertical guidance to the pilot. The system comprises of the following three components:

Localizer; Glide Slope; and Marker Beacons.

4.7.1 Localizer Localizer is installed at the STOP END of a runway. It provides central line information to the pilot approaching the aircraft for landing. The localizer signal is transmitted at the far end of the runway.

Figure 4.7-1: ILS system

The localizer coverage sector extends from the centre of the localizer antenna system to distances of 10 NM to 25 NM depending on the type of system used.

Radio Navigation

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4.7.2 Glide Slope Glide slope is installed at the APPROACH END of a runway. The transmitter is located 750 to 1,250 feet (ft) down the runway from the threshold, offset 400 to 600 ft from the runway centerline. The Glide path is adjusted to project an angle of 20 (degrees) above the horizon. This angle may vary between 20 and 4.50 degrees depending upon obstructions along an approach angle. The Glide Slope is to provide signals sufficient to allow satisfactory along the glide path to a distance of 10 NM. 4.7.3 Marker Beacons Marker beacons associated with ILS are designated as Outer Marker (OM), Middle Marker (MM) and Inner Marker (IM) and are located along a localizer front course at specific distances from the approach end of the runway. Outer Marker is located at 4 to 7 miles from the approach end of a runway and identified by transmission of continuous dashes. The OM activates PURPLE light on Pilots instrument panel. Middle Marker is located at approximately 3,500 feet (1050 meters) from the approach end of runway and identified by transmission of alternating dots and dashes. The MM activates AMBER light on Pilots instrument panel. Inner Marker is identified by transmission of continuous dots transmitted at a rate of 6 dots per second. It is installed between 250 feet and 1500 feet (450 meters) from the runway threshold. The IM signal activates WHITE light. 4.7.4 ILS Airborne Indication a) Cross Point Indicator CPI is prominently located in front panel of the pilot and used to indicate ILS signals. The vertical needle in CPI indicates position of the Localizer course and tells the pilot whether aircraft is right on the central line of the runway or deviating on left or right from the central line. Horizontal needle in CPI indicates the position of the aircraft with respect to glide angle. b) ILS Marker Receiver It consists of three-light indicator mounted on the instrument panel in the aircraft. Activation of these lights is controlled by the modulating frequencies of OM, MM and IM as described earlier. The use of the light indicator with aural marker receiver enables pilot to have a double check when an aircraft passes over the markers.


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4.7.5 ILS Facility Performance Categories ILS is classified by category in accordance with the capabilities of the ground equipment. Facility Performance Category-I Operation An ILS which provides guidance information from the coverage limit of the ILS to the point at which the localizer course line intersects the ILS glide path at a height of 60 m (200 ft) or less above the horizontal plane containing the threshold. Category I ILS provides guidance information down to a decision height (DH) of not less than 200 ft. Facility Performance Category-II Operation An ILS which provides guidance information from the coverage limit of the ILS to the point at which the localizer course line intersects the ILS glide path at a height of 30 m (100 ft) or less above the horizontal plane containing the threshold. A DH of not less than 100 ft. is, thus, authorized for Category II ILS approaches. Facility Performance Category-III Operation This category of operation is further divided into Category IIIA, Category IIIB, and Category IIIC operations. It provides guidance information at a decision of lower than 30 meters to no decision height, depending upon the type of sub-category being used. 4.7.6 Two ILS at opposite ends of a single runway At a location where two separate ILS facilities serve at opposite ends of a single runway, an interlock should ensure that only the ILS serving the approach direction shall radiate.

4.8 Microwave Landing System (MLS) The Microwave Landing System (MLS) originated in the early 1970's. The MLS is a precision approach and landing guidance system which provides position information and various ground to air data. The position information is provided in a wide coverage sector and is determined by an azimuth angle measurement, an elevation angle measurement and a range (distance) measurement. The information provided by MLS includes Approach azimuth, High rate approach azimuth, Approach elevation, Flare elevation, Back azimuth, 360° azimuth, Basic data and Auxiliary data. Basic Data is the data transmitted by the ground equipment that are associated directly with the operation of the landing guidance system. Auxiliary Data is the data, transmitted in addition to basic data, that provide ground equipment siting information for use in refining airborne position calculations and other supplementary information.

Radio Navigation

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The MLS coverage extends longitudinally, from the approach azimuth antenna, to the distance of 41.7 km (22.5 NM); and vertically upto a height of 6000 meters (20,000 ft).

4.9 Ground Radio Navigation Facilities in Pakistan Ground navigation facilities installed in Pakistan for civil air traffic are listed in table 4.9-1.

4.10 Provision of information on the operational status of radio

navigation aids Aerodrome control towers and units providing approach control service shall be provided without delay with information on the operational status of radio navigation aids essential for approach, landing and take-off at the aerodrome(s) with which they are concerned.

4.11 Secondary power supply for radio navigation aids and communication systems

Radio navigation aids and ground elements of communication systems of the types specified in Annex 10 shall be provided with suitable power supplies and means to ensure continuity of service appropriate to the needs of the service provided. Power Supply Switch-Over Times

The power supply switch-over times for radio navigation aids and ground elements of communications systems are dependent on the type of runway and aircraft operations to be supported. Table 4.11-1 indicates representative switch-over times which may be met by power supply systems currently available.


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Table 4.8-1 : Ground Navigation Aids in Pakistan

Location Radio Navigation Facility

Remarks NDB

VOR/DME

DVOR/DME

ILS

Bahawalpur Airport

Bannu Airport

Chitral Airport Military Facility

D G khan Airport

D I Khan Airport DME Not Available

Dalbadin Airport

Faisalabad Airport

Gawadar Airport

Gilgit Airport

Hangu Fac. withdrawn

Hyderabad Airport

Islamabad Airport * * Military Facility

Jacobabad Airport Military Facility

Jiwani Airport

Karachi Cape Monze

Karachi Chore

Karachi Gharo

Karachi JIAP

Khuzdar Airport Fac. withdrawn

Lahore AIIP

Lahore Sheikhupura

Moen Jo Daro Airport

Multan Airport

Multan Bindu DME Not Available

Muzafarabad Airport

Nawab Shah Airport

Ormara Airport

Panjgur Airport

Pasni Airport

Peshawar Airport * * Military Facility

Quetta Airport * * Military Facility

Rahim yar Khan Airport

Rawala Kot Airport

Saidu Sharif Airport Fac. withdrawn

Sewhan Sharif Airport

Skardu Airport

Sukkur Airport

Turbat Airport

Zhob Airport

Facility installed

Radio Navigation

4-10

Table 4.11-1: Power supply switch-over times for ground-based radio aids used at aerodromes

5. RADAR

5.1 Introduction

The term “RADAR” is derived from “RAdio Detection And Ranging”. It is device that

uses radio waves to detect the presence of a target and to determine its distance or range. History The first practical radar system was produced in 1935 in England by Sir Robert Watson-Watt (a Scottish origin physicist) By the 1940s, and the outbreak of World War II, the first useful RADAR systems were in place. Germany, France, Great Britain, and the United States all used RADAR to navigate their ships, guide their airplanes, and detect enemy craft before they attacked. After the close of World War II, radar assumed a major role in civil aviation. Use of Radar Radars are used in many applications such as: MET (Observation & Forecasting) Missile Guidance Speed Tracking Land Mine Detection Geological Exploration (Ground Penetrating Radar) Air Traffic Control (ATC) The radars used in ATC can be broadly classified as

En-route Radar Terminal Approach Radar Precision Approach Radar Ground Movement Radar

Because of different design parameters, no single radar set can perform all of radar functions. Types of Radar

a) Primary Radar b) Secondary Radar

Radar

5-2

5.2 Primary Radar It provides “Range and Bearing” information to the Air Traffic Control Center. It does not need cooperation of the aircraft for it depends upon reflection of the radio waves transmitted by the system itself. The primary radar transmits radio waves into the air in a specific direction and are received when they are reflected by an object in the path of the beam. RANGE in radar is determined by measuring the time, radio wave takes, from the radiation to return of its echo (reply or reflection of a target); whereas DIRECTION is determined from the position of antenna at the time of reception of signal. Primary radar operates within UHF band. L-band, and S-band radar are commonly used in ATS application.

5.3 Secondary Radar Secondary Radar, or Secondary Surveillance Radar (SSR) as generally called nowadays, was originally named as IFF “Identification Friend or Foe” system. It is composed of two main equipments; one installed at Ground called „INTERROGATOR‟ and other fitted in the aircraft called as „TRANSPONDER‟. It provides “identification and altitude” information to ground ATC. It works with cooperation of the aircraft. The information produced by the Secondary Radar is therefore function of both ground equipment and airborne equipment. 1030 MHz is used as the carrier frequency of the interrogation and 1090 MHz is used as the carrier frequency of the reply transmission.

5.4 Radar Display System Radar Display System, mainly, performs the following functions:

1. Reception of raw videos and (processed) data from radar heads 2. Radar Track processing 3. Radar and Flight Plan data processing 4. Data Distribution to various peripherals (monitors, printers etc) 5. Display/Representation of information (on radar scope)

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Management of Airport Electronics Facilities

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