1. INSTRUMENT
LANDING
SYSTEM (ILS)
Amideebin Azizan
Present to
MR. MuzaffarMustapha
Air Traffic Controller of KLIA
Department of Civil Aviation
Malaysia

2. SECTION 1

3. Outlines of ILS
•
•
•
•
•
•
•
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Introduction to ILS
What is ILS?
The Uses of ILS
ILS Components
How Localizer Works
How Glide Path Works
ILS Categories
Marker Beacons

4. What Is ILS?
• 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?

5. History of ILS
The first scheduled passenger airliner to land
using ILS was in 1938.

6. The Uses of ILS
• To 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.
• To provide an aircraft with a precision final
approach.
• To help the aircraft to a runway touchdown point.
• To provide an aircraft guidance to the runway both
in the horizontal and vertical planes.
• To increase safety and situational awareness.

7. Flight Profile

8. Poor Visibility Landings
• Scheduled service would be impossible without a
way to land in poor weather.

9. Poor Visibility Landings

10. Runway Approach
Non-Instrument Runway (NI)
Precision Runway (P)
Aiming
point
Touchdown
zone
Threshold
Non-Precision Runway (NP)
10

11. Types of Runway Approach
1.Non-Instrument Runway (NI)
•
A runway intended for the operation of aircraft using visual
approach procedure
2. Instrument Runway
•
A runway intended for the operation of aircraft using instrument
approach procedures
a) Non-Precision Runway (NP)
•
An instrument runway served by visual aids and a non-visual aid
providing at least lateral guidance adequate for a straight-in
approach
b)
Precision Runway (P)
•
Allow operations with a decision height and visibility
corresponding to Category
1, or II, or III

12. ILS category
Height above touch down (HAT)/decision
height (DH)
Runway visual range
CAT I
HAT not less than 200 feet
Not less than 1800 feet
CAT II
HAT not less than 100 feet
Not less than 1200 feet
CAT III A
No decision height
Not less than 700 feet
CAT III B
No decision height
Not less than 150 feet
CAT III C
No decision height
No RVR minimum

13. CAT 1
• 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.

14. CAT 2
• 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.

15. CAT 3 -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)

16. CAT 3-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.

17. CAT 3-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.

18. Precision Runway (P)
Categories
• Runway Threshold: Beginning of runway for landing.
• Touchdown zone: The first point for the aircraft shoul touch
the runway during landing.
• Aiming point: serves as a visual aiming point for a landing
aircraft.

19. ILS Components
•
•
ILS consists of Ground Installations and Airborne
Equipments
There are 3 equipments for Ground Installations, which
are:
1.
2.
3.
•
Ground Localizer (LLZ) Antenna – To provide horizontal
navigation
Ground Glide path (GP) Antenna – To provide vertical
navigation
Marker Beacons – To enable the pilot cross check the aircraft’s
height.
There are 2 equipments for Airborne Equipments, which
are:
1.
2.
LLZ and GP antennas located on the aircraft nose.
ILS indicator inside the cockpit

20. ILS Components
ILS Indicator inside the cockpit
Ground Localizer
Antenna
Ground Glide Path Antenna

21. ILS Indicator
Signal Integrity Flag
Indicates if instrument
is unreliable
Localizer
Glidepath
Deviation from
Deviation from
optimal glide path runway centre line
“Dots”
Each “dot” on the
instrument represents 2°
of deviation

22. How ILS works?
• Ground localizer antenna transmit VHF signal in
direction opposite of runway to horizontally guide
aircraft to the runway centre line.
• Ground Glide Path antenna transmit UHF signal in
vertical direction to vertically guide aircraft to the
touchdown point.
• Localizer and Glide Path antenna located at
aircraft nose receives both signals and sends it to
ILS indicator in the cockpit.

23. Cont.
• These signals activate the vertical and
horizontal needles inside the ILS indicator
to tell the pilot either go left/right or go
up/down.
• By keeping both needles centered, the
pilot can guide his aircraft down to end of
landing runway aligned with the runway
center line and aiming the touch down.

24. ILS Components
Marker Beacons: the
height aircraft
Glide Path:
vertical guidance
Localizer:
horizontal guidance
24

25. Question Banks
• What is Localizer and how does it works?
• What is Glide Slope and how does it works?
• An Airport with an ILS is often rated as Cat 1 or Cat II or Cat III.
Explain the definition of these.
• Explain Outer Marker, Middle Marker and Inner Marker of ILS
system.

26. Localizer
• Localizer is the horizontal antenna array located at the
opposite end of the runway.
• Localizer operates in VHF band between 108 to 111.975 MHz

27. How Localizer Works
• Localizer transmit two signals which overlap at the
centre.
• 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
centre line from the right, it will receive more of the
150 Hz modulation than 90Hz modulation.
• Difference in Depth of Modulation will energizes the
vertical needle of ILS indicator.
• Thus, aircraft will be given the direction to GO LEFT.

28. How Localizer Works
Left
Right

29. Localizer
Needle indicates direction
of runway.
Centered Needle = Correct
Alignment

30. Glide Path Antenna Array
• Glide Path 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

31. How Glide Path Works
• 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.
• Difference in Depth of Modulation will energizes the
horizontal needle of ILS indicator.
• Thus, aircraft will be given the direction to GO DOWN.

32. How Glide Path Works

33. Glide Path
Needle indicates
above/below glide path.
Centered Needle = Correct
Glide path

34. Marker Beacons
• 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.
• The correct height the aircraft should be at when the signal is
received in an aircraft.

35. Marker Beacons
Outer marker
• The outer marker should be located about 7.2 km from the
threshold.
• The modulation is repeated Morse-style dashes of a 400 Hz
tone.
• The cockpit indicator is a blue lamp that flashes accordingly
with the received audio code.
• The purpose of this beacon is to provide height, distance and
equipment functioning checks to aircraft on intermediate
and final approach.

36. Marker Beacons
Middle marker
• The middle marker should be located so as to indicate,
in low visibility conditions.
• Ideally at a distance of 1050m from the threshold.
• The cockpit indicator is an amber lamp that flashes in
accordingly with the received audio code.

37. Marker Beacons
Inner marker
• The inner marker, shall be located so as to indicate in low
visibility conditions.
• This is typically the position of an aircraft on the ILS as it
reaches Category II minima.
• The cockpit indicator is a white lamp that flashes in
accordingly with the received audio code.

38. Advantages of ILS
• The most accurate approach and landing aid that is used by
the airliners.

39. Disadvantages of ILS
• Interference due to large reflecting objects, other vehicles or
moving objects.
• This interference can reduce the strength of the directional
signals.

40. ILS Protected Area
• ILS Critical Area- Aircraft and Vehicles are excluded during all
ILS operations.
• ILS Sensitive Area

41. SECTION 2

42. Outlines of ATC
•
•
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What is ATC?
How does the ATC function?
The problem with ATC
The solution

43. •
Air Traffic Controller

44. What is ATC system?
• ATCS or ATC is a government run organization that is part of
FAA and DCA
• The ATC control all the air traffic on the Malaysia (DCA)
• Controller can gives the aircraft attitude, speed and direction
at any time to the pilot
• The controller also gives directions and weather forecast to
the pilot. If this command were to missed or interpreted
differently , the result could be catastrophic.

45. How does ATC function
• When the aircraft take-off, the departure control which is in the terminal
radar control facilities TRACON give the aircraft direction while the aircraft
remain the TRACON airspace.
• It then switches over the middle
zone, where the air route traffic
control center ARTCC take over from the
TRACON
• In the ARTCC zone two controllers monitor
the aircraft, called the radio associate
controllers

46. • The associate and radar controller work together in
charge of their own zone. The radar controller controls
all air to ground communication to maintain aircraft
separation within the zone and coordinates activities
with others sector and/or center

47. The Problem of ATC
• The technology used with the
ATC is outdated
*The radar that are used date
back to WW2
*The radio sets that are used
date all the ways back to the
1960s
• There is an excessive amount
of AT congestion
*Too many aircraft flying means
that the airways are not safe,
and airborne collisions are more
likely to happen
• Weather
*Thunderstorm cause major delays
if not correctly redirected
*poor Visibility

48. The Solution
• First, replace all of the old
technology with the new
technology
*GPS systems installed in planes
and controlled
*satellites used to give weather and
create flight maps and routes
• Weather issues can be solved by
implementing the technology of
satellite
*Air routes can be changed via GPS
if a storm is predicted
• Airways Congestion
*New technology can be
implemented to solve this problem.
-Aircraft will get ’ turn by
turn’ directions to get to
destinations and to avoid other
aircraft
*Replace all the old jets, with
newer, more fuel efficiency jets.
-newer jets can fly through
the air at faster rates and do not
struggle as much as older jets.

49. SECTION 3

50. Future Development

51. ILS VS MLS

52. What is MLS?
• MLS (Microwave Landing System) is an advanced
precision approach and landing system.
• MLS was developed to improve the uses of ILS
system, however only few Airports have MLS
installations.
• MLS operates in the Super High Frequency (SHF)
between 5.031 to 5.090GHz.

53. Advantages of MLS
• MLS provide large coverage signals even in very poor
visibility.
• As MLS signals have large coverage, this will increase
runway utilization.
• MLS also has more channels which can avoid the signal
interferences.
MLS Coverage

54. MLS vs ILS
• Aircraft flying into Heathrow Airport in fog or poor
visibility.
• On a clear day, about 44 planes an hour land at
Heathrow.
• However, if the visibility drops and aircraft have to use
the ILS system to land, only 24 aircraft could land per
hour.
• This is because the radio transmitter at the end of the
runway needs good line of sight to the approaching
aircraft, but because it is at the far end of the
runway, planes have to land and taxi clear before a full
signal is restored.
• However, MLS allows an extra six aircraft an hour to
land, meaning that while fog will still cause disruption, its
effects will be less prominent.

55. MLS Ground Installations
An MLS azimuth (horizontal) guidance
station

56. MLS Ground Installations
An MLS elevation (vertical) guidance station

57. ATC NEXT GEN 2018

58. NEXt Gen 2018
• A government run
project to upgrade the
technology of the ATC
• Upgrades include a GPS
and satellite system in
every airplane
• Next Gen 2018 has two
major fundamental
problems
• The project has no marketbased infrastructure to
support all the ATC receiving.
-Without this, the project
would be just like expanding a tollfree highway. Sooner or later, the
highway will be just as crowded as
it was before.
• Next Gen 2018 also might have a
problem implementing the right
technology.
• The whole process of upgrading
the ATC will happen again.

59. SECTION 4

60. ILS related to the ATC
• ILS is the equipment that guide the pilot landing to the
touchdown point and also known as the ATC technology
• This equipment is the helpful to the ATC because the ATC no
need to
*Guide the pilot by their self.
• The ATC just control the aircraft at the TRACON area and guide
to the marker beacon area for aircraft connecting by antenna
to the ILS for make a landing.
• This equipment was supporting the ATC and it’s a useful to the
aircraft and also the ATC got the benefit from that.

61. Resources
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•
•
•
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Lecture Note- Mr Muzaffar and Major Maya
Wikipedia website
FAA website
NASA website
DCA website
New Technology of ILS –PDF file

62. Conclusion
• For airport all over the world, cost-efficiency, environmental
protection and passenger comfort are at the top of the agenda.
However, due to the complexity of everyday airport operations and
new aircraft fleet to achieving these goals is uncertainties and this
is where equipment like ILS and ATC working principles/procedure
helping to minimize error and problem although increasing
efficiency in flight scheduling procedure , safety, time accuracy and
airport profitability
Result: Improved
overall situational awareness and
flight operation quality

63. SPECIAL THANKS TO
MALAYSIA AIRPORT
HOLDINGS BERHAD
Mr Muzaffar Mustaffa
Major Maya
KPMC
Q&A