ILS paperwork air traffic control

2,124 views

Published on

Published in: Education, Technology, Business
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
2,124
On SlideShare
0
From Embeds
0
Number of Embeds
5
Actions
Shares
0
Downloads
78
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

ILS paperwork air traffic control

  1. 1. Instrument Landing System (ILS) Case Study Table of contents Contents Acknowledgement… …………………………………………………………….. I 1.0: Introduction and Its History………………...………………………..……. 1 2.0: Instrumentation…………….....…………………………………….............. 1 3.0: Instrument Landing System (ILS)...….…………….……………………… 5 3.1: Equipment ……………………………………….............................. 6 3.1.1: Equipment’s for Ground Installations…………………… 6 3.1.2: Equipment’s for Airborne………………………………… 6 3.2: Component…………………………………………………………… 7 3.2.1: Localizer……………………………………………………. 3.2.1.1: Localizer Back course…………………………… 7 8 3.2.2: Glide Path………………………………………………….. 9 4.0 Marker Beacon……………………………………………………………….. 10 4.1 Outer Maker………………………………………………………….. 11 4.2 Middle Maker………………………………………………………… 12 4.3 Inner Maker………………………………………………………….. 12 5.0: Monitoring of ILS…….………………………………………………….… 13 6.0: Approach Lighting……………………………………………….................. 14 7.0: ILS Categories………………………………………………………………. 15 1|Page
  2. 2. Instrument Landing System (ILS) Case Study 7.1: Categories….………………………………………………… 15 7.1.1 CAT 1……………………………………………….. 15 7.1.2 CAT 2……………………………………………….. 15 7.1.3 CAT 3(a)…………………………………………….. 15 7.1.4 CAT 3(b)……………………………………………. 16 7.1.5 CAT 3(c)……………………………………………. 16 8.0: ILS Critical Area……………………………………………………………. 18 8.1 Snow Removal……………………………………………….. 20 9.0: ILS System Work…………………………………………………………… 23 9.1: Individual Part……………………………………………… 24 10.0: Rate of Decent Formula……………………………………………………. 25 11.0: Benefits of ILS……………………………………………………………… 26 11.1 Disadvantages of ILS………………………………………. 27 12.0: Future Development……………………………………………………… 27 13.0: Conclusion…………………………………………………………………. 28 14.0: Bibliography……………………………………………………………….. 29 1.0 Introduction and Its History 2|Page
  3. 3. Instrument Landing System (ILS) Case Study Instrument Landing System is landing navigational Aids that are used widely in airlines and it also using radio waves to transmit signal.Radio isthe transmission and reception of radio waves, especially those carrying audio messages.Navigation is the process of plan and directs the route of aircraft by using instruments or maps.Aircraft Communication is the delivery of information to or from aircraft by radio or signals1.Air Navigation is the action of plotting and directing the route of an aircraft through theair from one place to another2. One of the most difficult tasks a pilot has to perform is to achieve a smooth and safe landing. Early pilots landed on an open field, facing any direction that gave them the best angle relative to the wind. But as traffic grew and more aircraft began to use airports rather than farms or fields, landings became limited to certain directions. Landing aids were developed to help pilots find the correct landing course and to make landing safer. Airports had begun using lights in the late 1920s, when landing fields were marked with rotating lights so they could be found after dark. In the early 1930s, airports installed the earliest forms of approach lighting. These indicated the correct angle of descent and whether the pilot was right on target. Their approach path was called the Glide path Or Glideslope. Gradually, the colours of the lights and their rates of flash became standard worldwide based on International Civil Aviation Organization (ICAO) standards. The Air Mail Service'sintermediate or emergency, landing fields that it established along the air route used rotating electric beacons and lights that were set around the perimeter of the field3. Developed in the 1940s, the aid consisted of lights in rows that showed the pilot a simple funnel of two rows that led him to the end of the runway. Other patterns showed him when he 1 NASA Thesaurus, Washington, DC. Adapted from the United States Air Force Dictionary. 3 ICAO articles 2 july2001PDF format page 12 –history of ILS 2 3|Page
  4. 4. Instrument Landing System (ILS) Case Study was off to the right or left, or too high or low. The system was inexpensive to build and operate although it had some limitations and was not suitable for certain airports. Radio navigation aids also assisted in landing. One type, introduced in 1929, was the fourcourse radio range, where the pilot was guided by the strength of Morse code signals. Another type that was tried experimentally was the low-frequency radio beam4. These radio beams flared outward from the landing point like a “V,” so at the point farthest from the runway, the beams were widely separated and it was easy for the pilot to fly between them. But near the landing point, the space between the beams was extremely narrow, and it was often easy for the pilot to miss the exact counterpoint that he had to hit for landing. Another new method had a pilot tune into a certain frequency at a checkpoint far from the airport, and then uses a stopwatch to descend at a precise rate to the touchdown area of the runway. This method also proved difficult. The Instrument Landing System (ILS) incorporated the best features of both approach lighting and radio beacons with higher frequency transmissions. The ILS painted an electronic picture of the glideslope onto a pilot's cockpit instruments. Tests of the system began in 1929, and the Civil Aeronautics Administration (CAA) authorized installation of the system in 1941 at six locations. The first landing of a scheduled U.S. passenger airliner using ILS was on January 26, 1938, as a Pennsylvania-Central Airlines Boeing 247-D flew from Washington, D.C., to Pittsburgh and landed in a snowstorm using only the ILS system. More than one type of ILS system was tried. The system eventually adopted consisted of a course indicator (called a Localizer) that showed whether the plane was to the left or right of the runway centreline, a glide path or landing beam to show if the plane was above or below the glide slope, and two marker beacons for showing the progress of approach to the landing 4 ICAO articles 2 july2001PDF format page 14 –history of ILS 4|Page
  5. 5. Instrument Landing System (ILS) Case Study field. Equipment in the airplane allowed the pilot to receive the information that was sent so he could keep the craft on a perfect flight path to visual contact with the runway. Approach lighting and other visibility equipment are part of the ILS and also aid the pilot in landing. In 2001, the ILS remains basically unchanged. By 1945, nine CAA systems were operating and 10 additional locations were under construction. Another 50 were being installed for the army. On January 15, 1945, the U.S. Army introduced an ILS with a higher frequency transmitter to reduce static and create straighter courses, called the Army Air Forces Instrument Approach System Signal Set 515. In 1949, the International Civil Aviation Organization (ICAO) adopted this army standard for all member countries. In the 1960s, the first ILS equipment for fully blind landings became possible. The development of radar during World War II led to the development of a new precisionbeam landing aid called Ground Control Approach (GCA). GCA worked along with the ILS to help planes land at busy airports. By 1948, Distance Measuring Equipment(DME) was being used to provide data relating to the plane's distance from the ground. The installation of other radar continued with the air-route surveillance type of radar and the airport-surveillance radars that were installed at a number of airports in the mid-1950s. These helped air traffic controllers with their job6. Lights still play an important part in landing. Modern approach lighting can be oriented to accommodate any obstructions located near the airport that the pilot may need to avoid before beginning his descent to the runway. Lights can even be set at a second angle for larger aircraft because those cockpits are farther off the ground and the angle of descent will look 5 ICAO articles 2 july2001PDF format page 14 –history of ILS Wikipedia articles/www.wikipedia.com/instrumentlandingsystem 6 5|Page
  6. 6. Instrument Landing System (ILS) Case Study different to pilots in these planes. Pilots flying into fields without any staff can often turn landing lights on or off themselves or change their brightness by tuning their radio to a certain frequency and clicking their transmitter. Helicopters have used visual landing procedures for most of their history, and on June 12, 1987, the FAA opened its national concepts development and demonstration heliport. This research heliport was fully equipped with items such as a microwave landing system as well as precision approach path indication lights like those used by fixed-wing aircraft7. 2.0 Instrumentation Instrument or equipment that uses is such as Aircraft’s Cockpit Instrument, Aircraft’s Antenna and Ground Based Equipment for picture example: Figure (2)1:Cockpit Instrument and ILS indicator 7 FAA website–http://159.136.429 6|Page
  7. 7. Instrument Landing System (ILS) Case Study Figure (2)2: Aircraft Antenna’s Figure (2)3: ILS-LocalizerFigure (2)4:ILS-Glide Path 3.0Instrument Landing System Based on figure (2)3 and figure (2)4 ILS is stand for Instrument Landing System. It has been existence for over 60 years. But today, it is still the most accurate approach and landing aid that is used by the airliners. Why need ILS? Scheduled service would be impossible without a way to land in poor weather. The Tests of using the first ILS began in 1929.The first scheduled passenger airliner to land using ILS was in 19388.The use of ILS is to guide the pilot during the approach and landing. It is very helpful when visibility is limitedand the pilot cannot see the airport and runway, to provide an aircraft with a precision final approach, to help the aircraft to a runway touchdown point, to provide aircraft guidance 8 FAA articles Flight Rules-Authors James Ramno-PDF format-page 5 7|Page
  8. 8. Instrument Landing System (ILS) Case Study to the runway both in the horizontal and vertical planes and to increase safety and situational awareness. 3.1 Equipment and Component 3.1 Equipment of ILS ILS consists of Ground Installations and Airborne Equipment.Ground-based instrument approach system that providesprecision guidance to an aircraft approaching and landing on a runway, using a combination of radio signals and, in many cases, to enable a safe landing and also guide the pilot during the approach and landing.It is very helpful when visibility is limited and the pilot cannot see the airport and runway. ILS component and Equipment also provide aircraft with a precision final approach. 3.1.1 There are 3 equipment’s for Ground Installations, which are: i. Ground Localizer (LLZ) Antenna– To provide horizontal navigation ii. Ground Glide path (GP) Antenna– To provide vertical navigation iii. Marker Beacons – To enable the pilot cross check the aircraft’s height. The 3 equipment above are shown on picture figure (2)3 and figure (2)4. 3.1.2 There are 2 equipment’s for Airborne Equipment’s, which are: i. Localizer (LLZ) and Glide Path (GP) antennas located on the aircraft nose. ii. indicator inside the cockpit The 2 equipment’s above are shown on picture figure (2)1 and figure (2) as for picture reference. 8|Page
  9. 9. Instrument Landing System (ILS) Case Study 3.2Components of ILS (Principles of Operation) 3.2.1 Localizer (LLZ) Localizer is the horizontal antenna array located at the opposite end of the runway and Localizer operates in VHF band between 108 to 111.975 MHz .Localizer transmit two signals which overlap at the center. The left side has a 90 Hz modulation and the right has a 150 Hz modulation. The overlap area provides the on-track signal. For example, if an aircraft approaching the runway center line from the right, it will receive more of the 150 Hz modulation than 90Hz modulation as shown in figure 3.1.2(1) below. Difference in Depth of Modulation will energize the vertical needle of ILS indicator for example as figure 3.1.2.1(2). Thus, aircraft will be given the direction to GO LEFT. Figure 3.1.2.1(1) show how Localizer works Figure 3.1.2.1(2) Figure 3.1.2.1(3) Needle indicates direction of runwayCentered Needle = Correct Alignment 9|Page
  10. 10. Instrument Landing System (ILS) Case Study 3.2.1.1 Localizer Backcourseand Identification Modern localizer antennas are highly directional. However, usage of older, less directional antennas allows a runway to have a non-precision approach called a Localizer Backcourse. This lets aircraft land using the signal transmitted from the back of the localizer array for example are shown in figure 3.1.2.1.1(1). A pilot may have to fly opposite the needle indication, due to reverse sensing. This would occur when using a basic VOR indicator. If using an HSI, one can avoid reverse sensing by setting the front course on the course selector. Highly directional antennas do not provide a sufficient signal to support a backcourse. In the United States, backcourse approaches are commonly associated with Category I systems at smaller airports that do not have an ILS on both ends of the primary runway. Pilots may notice that they receive false glide slope signals from the front course ILS equipment. All glide slope information should be disregarded. Figure 3.1.2.1.1(1) Localizer array and approach lighting at Whiteman Air Force Base, Knob Noster, Missouri 10 | P a g e
  11. 11. Instrument Landing System (ILS) Case Study 3.2.2 Glide Path / Glide Slope Glide Path or Glide Slope is the vertical antenna located on one side of the runway about 300 m to the end of runway. Glide Path operates in UHF band between 329.15 and 335 MHz.Glide path produces two signals in the vertical plane. The upper has a 90 Hz modulation and the bottom has a 150 Hz modulation. For example, if an aircraft approaching the runway too high, it will receive more of the 90 Hz modulation than 150Hz modulation as shown in figure 3.1.2.2 below. Difference in Depth of Modulation will energizes the horizontal needle of ILS indicator.Thus, aircraft will be given the direction to GO DOWN.Glide Path errors can occur if terrain is sloping or is uneven in front of the antenna. Since antennas point in a single direction, only “straight” approaches are available. Figure 3.1.2.2(1) Show How Glide Path Works Figure 3.1.2.2(2) Needles indicates above/below glide path. 11 | P a g e
  12. 12. Instrument Landing System (ILS) Case Study 4.0 Marker Beacon Figure 4.0(1) Marker Beacons Cross check the height aircraft Marker beacons operating at a carrier frequency of 75 MHz are provided. When the transmission from a marker beacon is received it activates an indicator on the pilot's instrument panel and the tone of the beacon is audible to the pilot. The distance from the runway at which this indication should be received is published in the documentation for that approach, together with the height at which the aircraft should be if correctly established on the ILS. Figure 4.0(1) are show marker beacon provides a check on the correct function of the glideslope. In modern ILS installations, a DME is installed, colocated with the ILS, to augment or replace marker beacons. A DME continuously displays the aircraft's distance to the runway. 12 | P a g e
  13. 13. Instrument Landing System (ILS) Case Study Figure 4.0(2) Show how ILS component and equipment works and intercepted during aircraft landing 4.1 Outer Maker The Outer Marker is normally located 7.2 Kilometres (3.9 NMI; 4.5 MI) from the threshold except that, where this distance is not practical, the outer marker may be located between 6.5 To 11.1 Kilometres (3.5 to 6.0 NMI; 4.0 to 6.9 mi) from the threshold9. The modulation is repeated Morse-style dashes of a 400 Hz tone. The cockpit indicator is a blue lamp that flashes in unison with the received audio code as shown in figure 4.1(1). The purpose of this beacon is to provide height, distance and equipment functioning checks to aircraft on intermediate and final approach. In the United States, a NDB is often combined with the outer marker beacon in the ILS approach (called a Locator Outer Marker, or LOM); in Canada, low-powered Figure 4.1(1) Blue Outer Marker 9 Wikipedia-www.wikipedia.com/markerbeacon 13 | P a g e
  14. 14. Instrument Landing System (ILS) Case Study 4.2 Middle Maker The Middle Marker should be located so as to indicate, in low visibility conditions, the missed approach point, and the point that visual contact with the runway is imminent, ideally at a distance of approximately 3,500 ft (1,100 m) from the threshold. It is modulated with a 1.3 kHz tone as alternating Morse-style dots and dashes at the rate of two per second10. The cockpit indicator is an amber lamp that flashes in unison with the received audio code as shown in figure 4.2(1). Middle markers are no longer required in the United States, so many of them are being decommissioned. Figure 4.2(1)Amber Middle Marker 4.3 Inner Maker The Middle Marker should be located so as to indicate, in low visibility conditions, the missed approach point, and the point that visual contact with the runway is imminent, ideally at a distance of approximately 3,500 ft (1,100 m) from the threshold. It is modulated with a 1.3 kHz tone as alternating Morse-style dots and dashes at the rate of two per second11. The cockpit indicator is an amber lamp that flashes in unison with the received audio code as shown in figure 4.3. Middle markers are no longer required in the United States, so many of them are being decommissioned. Figure 4.3(1)White Inner Marker 10 Wikipedia-www.wikipedia.com/markerbeacon Wikipedia-www.wikipedia.com/markerbeacon 11 14 | P a g e
  15. 15. Instrument Landing System (ILS) Case Study 5.0 Monitoring It is essential that any failure of the ILS to provide safe guidance be detected immediately by the pilot. To achieve this, monitors continually assess the vital characteristics of the transmissions. If any significant deviation beyond strict limits is detected, either the ILS is automatically switched off or the navigation and identification components are removed from the carrier. Either of these actions will activate an indication ('Failure Flag') on the instruments of an aircraft using the ILS. 6.0 Approach Lighting Some installations include medium- or high-intensity approach light systems. Most often, these are at larger airports but many small general aviation airports in the Langkawi have approach lights to support their ILS installations and obtain low-visibility minimums. The approach lighting system (abbreviated ALS) assists the pilot in transitioning from instrument to visual flight, and to align the aircraft visually with the runway centerline. Pilot observation of the approach lighting system at the Decision Altitude allows the pilot to continue descending towards the runway, even if the runway or runway lights cannot be seen, since the ALS counts as runway end environment. In the U.S, an ILS without approach lights may have CAT I ILS visibility minimums as low as 3/4 Mile (runway visual range of 4,000 Feet) if the required obstacle clearance surfaces are clear of obstructions. Visibility minimums of 1/2 Mile (runway visual range of 2,400 Feet) are possible with a CAT I ILS approach supported by a 1,400-to-3,000-Foot-Long (430 to 910 M) ALS, and 3/8 Mile visibility 1,800-foot (550 M) visual range is possible if the runway has high-intensity edge lights, touchdown zone and centerline lights, and an ALS that is at least 2,400 Feet (730 M) long as shown in table 7.0. 15 | P a g e
  16. 16. Instrument Landing System (ILS) Case Study In effect, ALS extends the runway environment out towards the landing aircraft and allows low-visibility operations. CAT II and III ILS approaches generally require complex highintensity approach light systems, while medium-intensity systems are usually paired with CAT I ILS approaches. At many non-towered airports, the intensity of the lighting system can be adjusted by the pilot, for example the pilot can click their microphone 7 times to turn on the lights, then 5 times to turn them to medium intensity. 7.0 Instrument Landing System Categories ILS (instrument landing systems) are categorized according to their capability to provide for approach to a height above touchdown (HAT)/decision height (DH) and RVR (runway visual range). Different categories of ILS are as given in the table12. ILS category Height above touch down (HAT)/decision height (DH) Runway visual range Not less than 1800 feet CAT I HAT not less than 200 feet Not less than 1200 feet CAT II HAT not less than 100 feet Not less than 700 feet CAT III A No decision height Not less than 150 feet CAT III B No decision height No RVR minimum CAT III C No decision height Table 7.0 Categories of ILS 12 : http://www.answers.com/topic/ils-categories#ixzz22vdTYjRD 16 | P a g e
  17. 17. Instrument Landing System (ILS) Case Study 7.1 There are three categories of ILS the operation. 7.1.1 Category I A minimal height of resolution at 200 feet (60,96 M), whereas the decision height represents an altitude at which the pilot decides upon the visual contact with the runway if he’ll either finish the landing maneuver, or he’ll abort and repeat it. The visibility of the runway is at the minimum 1800 feet (548,64 M) The plane has to be equipped apart from the devices for flying in IFR (Instrument Flight Rules) conditions also with the ILS system and a marker beacon receiver. 7.1.2 Category II A minimal decision height at 100 feet (30,48 M) The visibility of the runway is at the minimum 1200 feet (365,76 M) The plane has to be equipped with a radio altimeter or an inner marker receiver, an autopilot link, a raindrops remover and also a system for the automatic draught control of the engine can be required. The crew consists of two pilots. 7.1.3 Category III -A A minimal decision height lower than 100 feet (30,48 M) The visibility of the runway is at the minimum 700 feet (213,36 M) The aircraft has to be equipped with an autopilot with a passive malfunction monitor or a HUD (Head-up di) 17 | P a g e
  18. 18. Instrument Landing System (ILS) Case Study 7.1.4 Category III - B A minimal decision height lower than 50 feet (15,24 M) The visibility of the runway is at the minimum 150 feet (45,72 M) A device for alteration of a rolling speed to travel speed. 7.1.5 Category III - C Zero visibility A precision instrument approach and landing with no decision height and no runway visual range limitations. A Category III C system is capable of using an aircraft's autopilot to land the aircraft and can also provide guidance along the runway surface. In contrast to other operations, CAT III weather minima do not provide sufficient visual references to allow a manual landing to be made. The minima only permit the pilot to decide if the aircraft will land in the touchdown zone (basically CAT III A) and to ensure safety during rollout (basically CAT III B). Therefore an automatic landing system is mandatory to perform Category III operations. Its reliability must be sufficient to control the aircraft to touchdown in CAT III A operations and through rollout to a safe taxi speed in CAT III B (and CAT III C when authorized)13. FAA Order 8400.13D allows for special authorization of CAT I ILS approaches to a decision height of 150 feet (46 M) above touchdown, and a runway visual range as low as 1,400 feet (430 M). The aircraft and crew must be approved for CAT II operations, and a heads-up 13 http://niquette.com/books/chapsky/skypix/ILS 18 | P a g e
  19. 19. Instrument Landing System (ILS) Case Study display in CAT II or III mode must be used to the decision height. CAT II/III missed approach criteria applies14. In Canada, the required RVR for carrying out a Cat I approach is 1600 feet, except for certain operators meeting the requirements of Operations Specification 019, 303 or 503 in which case the required RVR may be reduced to 1200 feet. In the United States, many but not all airports with CAT III approaches have listings for CAT IIIa, IIIb and IIIc on the instrument approach plate (U.S. Terminal Procedures). CAT III B runway visual range minimums are limited by the runway/taxiway lighting and support facilities, and would be consistent with the airport Surface Movement Guidance Control System (SMGCS) plan15. Operations below 600 runway visual range require taxiway centerline lights and taxiway red stop bar lights. If the CAT IIIB runway visual range minimums on a runway end were 600 feet (180 M), which is a common figure in the U.S., ILS approaches to that runway end with runway visual range below 600 feet (180 M) would qualify as CAT IIIc and require special taxi procedures, lighting and approval conditions to permit the landings. FAA Order 8400.13D limits CAT III to 300 runway visual range or better. Order 8400.13D, which was released during 2009, also allows special authorization CAT II approaches to runways without ALSF-2 approach lights and/or touchdown zone/centerline lights, which has expanded the number of potential CAT II runways16. In each case, a suitably equipped aircraft and appropriately qualified crew are required. For example, CAT IIIb requires a fail-operational system, along with a crew who are qualified 14 http://niquette.com/books/chapsky/skypix/ILS http://niquette.com/books/chapsky/skypix/ILS 16 http://niquette.com/books/chapsky/skypix/ILS 15 19 | P a g e
  20. 20. Instrument Landing System (ILS) Case Study and current, while CAT I does not. A head-up display which allows the pilot to perform aircraft maneuvers rather than an automatic system is considered as fail-operational. CAT I relies only on altimeter indications for decision height, whereas CAT II and CAT III approaches use radar altimeter to determine decision height. An ILS is required to shut down upon internal detection of a fault condition. With the increasing categories, ILS equipment is required to shut down faster, since higher categories require shorter response times. For example, a CAT I localizer must shutdown within 10 Seconds of detecting a fault, but a CAT III localizer must shut down in less than 2 Seconds17. 8.0 ILS Critical Sensitive Areas When CAT II/III operations are in progress, unauthorized vehicles and/or aircraft will not be permitted within the critical or sensitive areas. Examples of critical or sensitive areas are outlined in Figure C-3A and C-3B. Current regulatory requirements mandated in subpart 2 of Part VIII of the CARs are contained in ICAO Annex 10, vol. 1 Critical areas are defined as those where the presence of a vehicle or taxiing aircraft may possibly affect ILS signals. The depicted areas are theoretical, and will probably vary with individual sites. Actual critical areas can be defined only by experimentation and experience. When any portion of a designated sensitive area becomes suspect as a likely source of interference, that portion must be included as part of the critical area. “CAT II/III Hold” signs are posted on taxiways and must be observed by aircraft and vehicles when CAT II/III operations are being conducted. 17 http://niquette.com/books/chapsky/skypix/ILS 20 | P a g e
  21. 21. Instrument Landing System (ILS) Case Study a) When snow clearance is necessary, snow removal equipment may enter and remain in these areas. It is expected that vehicles must vacate these areas before an aircraft using the ILS for a CAT II/III approach has passed the Final Approach Fix (FAF) (usually a point 4 NM from threshold); such vehicles may not reenter until the aircraft has landed or commenced a missed approach. b) A telecommunications vehicle may be authorized to proceed to the ILS equipment buildings provided that an aircraft on a CAT II/III approach has not passed the FAF. If already at the building however, such a vehicle must remain parked there until authorized to move by ATC. c) No vehicle or aircraft will be permitted to cross or remain on an active CAT II/III runway, or on any other runway or taxiway where their presence could affect ILS signals, when an aircraft on a approach has passed the FAF. d) If there is a roadway in the glide path sensitive areas, no vehicle will be permitted to stop or park on that roadway. Signs must be posted to indicate these restrictions. 21 | P a g e
  22. 22. Instrument Landing System (ILS) Case Study 8.1 Snow Removal – Category II/III Glide Path Sites Accumulation of snow beyond certain depths in the monitor area may result in the monitor indicating alarm conditions, whereas the actual path parameters along the approach may not change significantly. A heavy accumulation of snow outside the monitor area may result in an increase in glide slope angle of approximately 0.1º per foot of snow. Under these conditions, snow clearing in the monitor area only would result in normal monitor indications, when in fact, the glide slope angle may have increased along the approach path. At the same time, a change in the coefficient of reflection and the relative heights of the transmitting antenna may also affect course structure. NAV CANADA delivers mandatory annual briefings to airport personnel responsible for snow measurement and removal at all of its ILS sites, regardless of precision approach category. Responsibilities for removal of snow and vegetation are as outlined in site specific agreements between the ILS owner/operator and the airport authority. The critical area is shown in Figure 8.0(1) and 8.0(2). This area is considered to be critical in terms of ground conditions, vehicles intrusion, etc. The removal of snow and vegetation is the responsibility of the Local Airport Authority (LAA). Excessive snow banks and vegetation along the approach and access roads at some locations may affect course structure, the degree being dependent on location of the approach road. Following a period of heavy snowfall and subsequent plowing, it may be necessary to have the banks cut down. This is particularly important in areas where snowblowing operations have created vertical snow cuts. Similarly, snow drifts or banks in the monitor area may affect monitor operation and must be tapered. 22 | P a g e
  23. 23. Instrument Landing System (ILS) Case Study 8.1 Example of ILS Critical Sensitive Areas Figure 8.0 (From ICAO Annex 10) Typical localizer critical and sensitive areas dimension variations for a 3 000 m (10 000 ft) runway Table below Based on Figure 8.0 Example 1 Localizer antenna aperture Example 3 B-747 Aircraft type Example 2 B-747 B-727 Typically 27 m (90 ft) (Directional dual frequency, 14 elements) Typically 16 m (50 ft) (Semi-directional, 8 elements) Typically 16 m (50 ft) (Semi-directional, 8 elements) Sensitive area (X, Y) Category I 600 m (2 000 ft) 300 m (1 000 ft) 60 m (200 ft) 110 m (350 ft) 60 m (200 ft) X 1 220 m (4 000 ft) 2 750 m (9 000 ft) 300 m (1 000 ft) Y Category III 600 m (2 000 ft) Y Category II X 90 m (300 ft) 210 m (700 ft) 60 m (200 ft) X 2 750 m (9 000 ft) 2 750 m (9 000 ft) 300 m (1 000 ft) Y 90 m (300 ft) 210 m (700 ft) 60 m (200 ft) 23 | P a g e
  24. 24. Instrument Landing System (ILS) Case Study Figure 8.0(2)(From ICAO Annex 10). Typical glide path critical and sensitive areas dimension variations Example 1 Example 3 B-747 Aircraft Type Example 2 B-727 Small & Medium* 915 m (3 000 ft) 730 m (2 400 ft) 250 m (800 ft) 60 m (200 ft) 30 m (100 ft) 30 m (100 ft) X 975 m (3 200 ft) 825 m (2 700 ft) 250 m (800 ft) Y Category II/III X Y Category I 90 m (300 ft) 60 m (200 ft) 30 m (100 ft) * Small and medium aircraft here are considered as those having both a length less than 18 m (60 feet) and a height less than 6 m (20 feet) 24 | P a g e
  25. 25. Instrument Landing System (ILS) Case Study 9.0 How does the Instrument Landing System work? The Instrument Landing System uses radio transmitters on the ground and receivers in the air to provide an aircraft with precise guidance for landing even in very low or zero visibility conditions. The ILS has two main parts: a localizer, which guides the airplane horizontally, and a glide slope, which guides the airplane vertically. The localizer uses a set of radio transmitters at the far end of a runway, and the glide slope uses a set of transmitters close to the near threshold of the runway. Receivers on the aircraft detect the localizer and glide slope transmissions. These highly directional radio transmissions are designed so that the aircraft receives a signal of perfect alignment only if it is right on the extended centerline of the runway and descending exactly along the required descent path for touchdown. The receivers on the aircraft are used to drive instruments that display the aircraft's position to the pilots, and they can be used to control autopilots that can fly the landing approach automatically. In most airliners, the ILS receivers can even land the plane entirely under automatic control, without any pilot intervention (this is called an "autoland"). This requires a special category of ILS, plus special ILS receivers on the airplane, and special training for the pilots. For more ordinary ILS approaches, the pilots normally take over from the autopilot (if it is in use) just before reaching the runway. Of course, pilots can fly the ILS approach by hand, too, by watching their instruments. ILS is routinely used any time the weather is poor, and often it is used all the time, as back-up to a visual approach. In the worst visbility conditions, autoland allows aircraft to land even if they pilots can't see anything at all outside the windows. 25 | P a g e
  26. 26. Instrument Landing System (ILS) Case Study 9.1 ILS Picture (Individuals Parts of ILS) Figure 9.1(1) the description and placement of the individual parts of the ILS system The Figure above show how ILS does work with the ILS Glide Slope and Localizer and also the component of Maker Beacon:i. Outer ii. Middle iii. Inner All the individual parts must work well to provide aircraft landing with the accurate path of runway. This system will guide the aircraft to the center of runway. 26 | P a g e
  27. 27. Instrument Landing System (ILS) Case Study 10.0 Rate-Of-Descent Formula A useful formula pilots use to calculate descent rates (standard 3° Glide Slope): Rate Of Descent = Ground Speed ⁄ 2 × 10 Or Rate Of Descent = Ground Speed × 5 For other glideslope angles: Rate Of Descent = Glide Slope Angle × Ground Speed × 100 / 60 The latter replaces tan α (see below) with Α/60, which is about 95% accurate up to 10°. Example: 120 KTS × 5 Or 120 KTS / 2 × 10 = 600 FPM The above simplified formulas are based on a trigonometric calculation: Rate Of Descent = Ground Speed × 101.25 × Tan Α where:  Α is the descent or Glideslope Angle from the horizontal (3° being the standard)  101.25 (FPM⁄KT) is the conversion factor from knots to feet per minute (1 KNOT ≡ 1 NM⁄H =6075 FT⁄H = 101.25 FPM) Example: Ground Speed = 250 KTS Α = 4.5 KTS 250 × 101.25FPM/KT × TAN 4.5 = 1992 FPM 27 | P a g e
  28. 28. Instrument Landing System (ILS) Case Study 11.0 The Benefits of an ILS (Instrument Landing System) The Instrument Landing System (ILS) is a precision approach navigational aid which provides highly accurate course, glide-slope, and distance guidance to a given runway. The ILS can be the best approach alternative in poor weather conditions for several reasons. 1. The ILS is a more accurate approach aid than any other widely available system. 2. The increased accuracy generally allows for lower approach minimums. 3. The lower minimums can make it possible to execute an ILS approach and land at an airport when it otherwise would not have been possible using a NonPrecision Approach Figure 11.0 Show When flying an ILS, you track the line formed by the intersection of the glide slope and localizer courses. 28 | P a g e
  29. 29. Instrument Landing System (ILS) Case Study 11.1Disadvantages of ILS Interference due to large reflecting objects, other vehicles or moving objects. This interference can reduce the strength of the directional signals. 12.0 Future Development of Instrument Landing System Microwave Landing Systems(MLS) were developed in the 1980s. These systems allow pilots to pick a path best suited to their type of aircraft and to descend and land from more directions than the ILS. Having different landing patterns can help reduce noise around airports and keep small aircraft away from the dangerous vortices behind large aircraft. MLS have been adopted in Europe as replacements for ILS. In the United States, however, the FAA halted further development of MLS in 1994. Instead, the FAA is considering the use of technology based on the Global Positioning System(GPS) instead of, or in addition to, existing microwave systems. The GPS uses satellites for navigation between airports and is exceedingly precise18. 18 Aeronautical navigation product 29 | P a g e
  30. 30. Instrument Landing System (ILS) Case Study 13.0 Conclusion An instrument landing system (ILS) isa ground-based instrument approach system that provides precision guidance to an aircraft approaching and landing on a runway, using a combination of radio signals and, in many cases, high-intensity lighting arrays to enable a safe landing during instrument meteorological conditions (IMC), such as low ceilings or reduced visibility due to fog, rain, or blowing snow. Additional aids may be available to assist the pilot in reaching the final approach fix. One of these aids is the NDB which can be co-located with or replace the outer marker (OM) or back marker (BM). It is a low-frequency non-directional beacon with a transmitting power of less than 25 watts (W) and a frequency range of 200 kilohertz (kHz) to 415 kHz. The reception range of the radio beacon is at least 15 nautical miles (NM). In a number of cases an en route NDB is purposely located at the outer marker so that it may serve as a terminal as well as an en route facility. So this equipment is very important to the aviation industry it is also the main factor of air transport is safe transport in the world than compare with ground and others. 30 | P a g e
  31. 31. Instrument Landing System (ILS) Case Study 14.0 Bibliography wikipedia. (2006, 06 04). Retrieved from http://wikipedia.com/makerbeacon Dictionary, A. (1999). US airforce dictionary. Retrieved from http://USairforce Elbert, R. (2005). FAA flight Rule. uniques. ICAO. (2001, july 2). PDF. Retrieved from http://ICAO/airport annexes NASA. (n.d.). NASA Theasaurus. Retrieved from Washington DC. Nirqutee. (2001). nirqurtee. Retrieved from http://niqurtee.com/books/chapsky/skypix/ils Rovertivesy. (n.d.). answer. Retrieved from http://www.answer.com/topic/ils-category 31 | P a g e

×