Instrument Landing System Flashcards
Is ILS a Precision or non Precision approach?
Precision
What does ils provide?
Accurate guidance both in Azimuth and elevation
What Conditions is ils designed for?
Low cloud or poor vis
Does ils operate continuously without assistance from ATC?
Yes
What does the localiser transmitter do?
Defined the extended centreline of the instrument runway. And,
Indicates deviation from the optimum lateral approach.
Where is the localiser situated?
Beyond the upwind end of the runway, 300m from the threshold
What does the Glidepath Transmitter do?
Defines the safe descent slope(normally 3 degrees). And, indicates deviation from optimum vertical approach path.
Where is the glidepath transmitter situated?
300m from the landing threshold and offset between 100-200m from the centre line
How many marker beacons are normally installed?
Normally 2 occasionally 3
What do marker beacons do?
Define ranges from the threshold
List the 3 types of marker beacons
Outer marker
Middle marker
Inner marker
How far is the outer marker from the threshold? What Hurtz does it operate on?
3-6nms 400Hz - -
How far is the middle marker from the threshold? What Hurtz does it operate on?
900-1200m from the threshold
1300Hz •-•
How far is the inner marker from the threshold? What Hurtz does it operate on?
300-450m from the threshold.
3000Hz ••••••
Regarding ILS what 4 things does the DME transponder do?
1) Provides Range info instead of marker beacons
2) DME channel frequency paired with localiser, therefore DME automatically tuned when ILS selected
3) Range If zero referenced to runway threshold
4) Accurate only with localiser coverage and up to 25,000ft
What frequency does the localiser operate on?
VHF band 108-112MHz
The localiser radiates two lobes that overlap by 5 degrees. True or False?
True.
When are the two lobes received of equal intensity by the aircraft?
When on The centreline
What is the coverage either side of the centre line out to 17nm?
35 degrees eitherside
What is the centre line coverage either side at 25nms?
10 degrees
What frequency does the glide path operate on?
UHF band
329.3-335MHz
The glidepath radiates 2 loves that overlap by 1 degree.
True or False?
True.
What is the maximum range of the glide path?
10nms
The glidepath is known as the ILS reference point. True or False?
True.
The overlapping area is normally sub tended an angle of 3 degrees to give continuous descending approach to touch down point.
True or False?
True
When will the aircraft receive signal of equal intensity from both glidepath lobes?
On the correct descent path.
What is the horizontal coverage either side up to 10nms on the glidepath?
8 degrees.
What is the vertical coverage from the centreline of the glidepath?
0.45x Glidepath below surface and 1.75x glidepath
What does the location of the GP aerial and approaching angle depend on? (5 things)
1) aircraft to use Aerodrome;
2) Terrain;
3) Runway Length;
4) meteorological conditions;
5) obstacles within Approach/missed Approach Area.
Indication equates to a height of 50ft as the aircraft crosses the threshold. So the ILS reference datum should be as close to 50ft as possible. True or False?
True.
If the glide path has an angle of 3.5 degrees. How many feet per nm will it descend?
350ft per nm
If the glide path has an angle of 3 degrees. How many feet per nm will it descend?
300ft per nm
If the glide path has an angle of 2.5 degrees. How many feet per nm will it descend?
250ft per nm
Are the localiser and Glidepath frequency paired?
Yes
ILS Garuda against mismatching, True or False?
True.
Only the localiser frequency needs to be selected/published on the flight deck. True or False?
True.
The ILS and marker boards are automatically monitored for their radiation fields. True or False?
True.
When will the ILS automatically cease to transmit navigation information?
If the power drops below acceptable level or anything abnormal happens.
When will the ILS switch off?
If the monitoring equipment fails.
What is indicated when a continuous tone is played by the ILS?
ILS is under maintenance or radiating for test purposes.
What does HSI stand for?
Horizontal Situation Indicator
What does OBS stand for?
Omni-directional Bearing Selector.
On the cockpit display each dot indicates how many degrees vertically and horizontally?
- 5 horizontal
0. 15 vertically
The edge of the centre ring in the cockpit display is the first dot of displacement. True or False?
True.
What 3 things cause the needles to remain centred on the cockpit display?
1) Receiver switched off
2) No signal is being received
3) In Centreline If both localiser and glidepath.
What 3 factors depend if the autoland on the ILS can be used?
1) A/C suitably equipped
2) Ground Transmitter protected from external performance
3) A/C movement on the ground in the vicinity of ILS equipment must be restricted.
List the 7 ILS categories
1) CAT 1
2) Lower than standard CAT1
3) CAT 2
4) Other than standard CAT2
5) CAT 3-A
6) CAT 3-B
7) CAT 3-C
What are the restrictions for CAT 1?
DH not lower than 200ft
Not less than 800m Visibility; or
RVR not less than 550m
What are the restrictions for “lower than standard CAT 1”?
DH not lower than 200ft
RVR not less than 400m
What are the restrictions for CAT 2?
DH not lower than 200ft but not lower than 100ft
RVR 350m
What are the restrictions for “other than standard CAT 2”?
DH 200-100ft
RVR not less than 350m
When is other than standard CAT 2 used?
Used if some/all Approach lights are out.
Can CAT 3 ILS operate with no Decision height?
Yes
What are the restrictions for CAT 3-A?
DH not lower than 100ft
RVR not less than 200m
What are the restrictions for CAT 3-B?
DH not lower than 50ft
RVR 200-75m
What are the restrictions for CAT 3-C?
NoDH
No RVR limitations
