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Questions and Answers
What angle provides azimuth coverage for an ILS Glide Path to a distance of 10 NM from the threshold?
What angle provides azimuth coverage for an ILS Glide Path to a distance of 10 NM from the threshold?
Which frequency band does an ILS glide slope operate in?
Which frequency band does an ILS glide slope operate in?
What action should be taken if more 90 Hz modulation than 150 Hz modulation is received on an ILS approach?
What action should be taken if more 90 Hz modulation than 150 Hz modulation is received on an ILS approach?
If the HSI compass rose is stuck on 200 degrees while aligned with the ILS localiser for runway 25, what will be the position of the localiser needle?
If the HSI compass rose is stuck on 200 degrees while aligned with the ILS localiser for runway 25, what will be the position of the localiser needle?
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To regain centreline and glide path on an ILS approach while receiving more 90 Hz modulation, the correct action would be to:
To regain centreline and glide path on an ILS approach while receiving more 90 Hz modulation, the correct action would be to:
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What is the reliable navigation information angular coverage for a 3° ILS glide path reaching 10 NM?
What is the reliable navigation information angular coverage for a 3° ILS glide path reaching 10 NM?
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Where is the ILS localiser transmitting aerial normally situated in relation to the runway?
Where is the ILS localiser transmitting aerial normally situated in relation to the runway?
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If an aircraft is outside the published ILS coverage angle, what may occur?
If an aircraft is outside the published ILS coverage angle, what may occur?
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What is the aural frequency of an outer marker transmitting on 75 MHz?
What is the aural frequency of an outer marker transmitting on 75 MHz?
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Which option is an ILS localiser frequency?
Which option is an ILS localiser frequency?
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What is the minimum accuracy a category III ILS system provides for landing guidance?
What is the minimum accuracy a category III ILS system provides for landing guidance?
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What frequency does the OUTER MARKER of an ILS facility transmit on?
What frequency does the OUTER MARKER of an ILS facility transmit on?
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What is the approximate change in rate of descent when the ground speed drops from 150 kt to 120 kt on a 3° glidepath?
What is the approximate change in rate of descent when the ground speed drops from 150 kt to 120 kt on a 3° glidepath?
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How does a 10 kt decrease in ground speed affect the required rate of descent on a 3° ILS glide path?
How does a 10 kt decrease in ground speed affect the required rate of descent on a 3° ILS glide path?
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What is the rate of descent necessary to maintain a 3.25° glide slope at a ground speed of 140 kt?
What is the rate of descent necessary to maintain a 3.25° glide slope at a ground speed of 140 kt?
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What ILS indication will show when an aircraft receives more 90 Hz modulation than 150 Hz?
What ILS indication will show when an aircraft receives more 90 Hz modulation than 150 Hz?
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Which of these statements about ILS systems is incorrect?
Which of these statements about ILS systems is incorrect?
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What consequence does an increase in modulation from the localiser indicate?
What consequence does an increase in modulation from the localiser indicate?
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What is the expected height of an aircraft on a 3 degree glide path when it is 4.5 NM from touchdown?
What is the expected height of an aircraft on a 3 degree glide path when it is 4.5 NM from touchdown?
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What visual and aural indications are associated with the ILS outer marker?
What visual and aural indications are associated with the ILS outer marker?
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How is the middle marker of an ILS facility identified both audibly and visually?
How is the middle marker of an ILS facility identified both audibly and visually?
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What is the required rate of descent to maintain a 3 degree glide path at a ground speed of 120 knots?
What is the required rate of descent to maintain a 3 degree glide path at a ground speed of 120 knots?
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While lined up on the ILS of runway 25, if the heading rose of an HSI is frozen on 200 degrees, where will the localiser needle be positioned?
While lined up on the ILS of runway 25, if the heading rose of an HSI is frozen on 200 degrees, where will the localiser needle be positioned?
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When may aircraft not enter the sensitive area of an ILS?
When may aircraft not enter the sensitive area of an ILS?
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What is the approximate rate of descent required to maintain a 3.3 degree glide path at a ground speed of 115 knots?
What is the approximate rate of descent required to maintain a 3.3 degree glide path at a ground speed of 115 knots?
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ILS is subject to false glide paths primarily due to which of the following reasons?
ILS is subject to false glide paths primarily due to which of the following reasons?
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What is the colour sequence when passing over the Outer, Middle, and Inner Marker beacons?
What is the colour sequence when passing over the Outer, Middle, and Inner Marker beacons?
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What is the coverage of the ILS glide slope in relation to the localiser centreline?
What is the coverage of the ILS glide slope in relation to the localiser centreline?
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What is the approximate altitude of an aircraft at the outer marker when the glide slope height is 50 FT above the threshold?
What is the approximate altitude of an aircraft at the outer marker when the glide slope height is 50 FT above the threshold?
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How is the operation principle of an ILS localiser transmitter characterized regarding its frequencies?
How is the operation principle of an ILS localiser transmitter characterized regarding its frequencies?
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What is the maximum height above the runway provided by a Cat III ILS glide path transmitter?
What is the maximum height above the runway provided by a Cat III ILS glide path transmitter?
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What is the required rate of descent to maintain a 3° glide path at a ground speed of 90 kt?
What is the required rate of descent to maintain a 3° glide path at a ground speed of 90 kt?
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What frequency range is assigned to all ILS marker beacons?
What frequency range is assigned to all ILS marker beacons?
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If the glide path is not operating, what is the typical response of the ILS?
If the glide path is not operating, what is the typical response of the ILS?
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What height must an ILS category II ground installation be capable of providing guidance to?
What height must an ILS category II ground installation be capable of providing guidance to?
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How far must a localiser provide horizontal coverage?
How far must a localiser provide horizontal coverage?
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When looking at modulations of 150 Hz and 90 Hz on a localiser, which statement is correct?
When looking at modulations of 150 Hz and 90 Hz on a localiser, which statement is correct?
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What is the upper limit of vertical coverage required for a localiser?
What is the upper limit of vertical coverage required for a localiser?
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Which of the following describes the correct radiation pattern of the Instrument Landing System (ILS) localiser?
Which of the following describes the correct radiation pattern of the Instrument Landing System (ILS) localiser?
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Which statement is true regarding false beams on a glide path?
Which statement is true regarding false beams on a glide path?
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Which facility associated with the ILS may be identified by a two-letter identification group?
Which facility associated with the ILS may be identified by a two-letter identification group?
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Which elements of an ILS transmit in the VHF band?
Which elements of an ILS transmit in the VHF band?
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What is true with respect to marker beacons?
What is true with respect to marker beacons?
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Why do ILS marker beacons not interfere with each other?
Why do ILS marker beacons not interfere with each other?
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How is the outer marker of ILS identified in an aeroplane?
How is the outer marker of ILS identified in an aeroplane?
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What is the azimuth and area coverage of a CAT I ILS localiser?
What is the azimuth and area coverage of a CAT I ILS localiser?
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To maintain a glide slope of 32.5 degrees at a ground speed of 140 knots, what is the approximate required rate of descent?
To maintain a glide slope of 32.5 degrees at a ground speed of 140 knots, what is the approximate required rate of descent?
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An ILS localiser can provide reverse sense indications at which condition?
An ILS localiser can provide reverse sense indications at which condition?
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What is the ILS glide path coverage in elevation for a 3o glide path?
What is the ILS glide path coverage in elevation for a 3o glide path?
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Which sequence of marker colours is correct for flying an ILS approach?
Which sequence of marker colours is correct for flying an ILS approach?
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Where is the ILS localiser typically positioned?
Where is the ILS localiser typically positioned?
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What CDI indications can be expected when an aircraft is flying downwind outside the coverage of the ILS?
What CDI indications can be expected when an aircraft is flying downwind outside the coverage of the ILS?
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What is the frequency band of the ILS glide path?
What is the frequency band of the ILS glide path?
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In which band does the ILS glide path operate?
In which band does the ILS glide path operate?
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What are the minima for a CAT II ILS approach?
What are the minima for a CAT II ILS approach?
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What kind of identification does the middle marker of an ILS have?
What kind of identification does the middle marker of an ILS have?
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How should the rate of descent (ROD) be adjusted when reducing speed on a 3o ILS approach from 150 knots to 120 knots?
How should the rate of descent (ROD) be adjusted when reducing speed on a 3o ILS approach from 150 knots to 120 knots?
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What causes errors in the ILS localiser beam?
What causes errors in the ILS localiser beam?
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What is the required rate of descent to maintain a 3o glide path at an approach speed of 150 kts?
What is the required rate of descent to maintain a 3o glide path at an approach speed of 150 kts?
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When using a CDI, what must be done to ensure proper navigation on the ILS?
When using a CDI, what must be done to ensure proper navigation on the ILS?
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What altitude does a Category 1 ILS provide accurate guidance down to?
What altitude does a Category 1 ILS provide accurate guidance down to?
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What is the maximum safe deviation below the glide path during an ILS approach as per ICAO 8168?
What is the maximum safe deviation below the glide path during an ILS approach as per ICAO 8168?
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Assuming a five dot display on an ILS localiser, what does each dot represent approximately?
Assuming a five dot display on an ILS localiser, what does each dot represent approximately?
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What does full deflection on a glide slope indicator indicate?
What does full deflection on a glide slope indicator indicate?
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Full scale deflection of the localiser needle indicates that the aircraft is approximately how many degrees offset from the localiser centre line?
Full scale deflection of the localiser needle indicates that the aircraft is approximately how many degrees offset from the localiser centre line?
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What frequency does the inner marker transmit?
What frequency does the inner marker transmit?
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What modulation frequencies are used on an ILS approach?
What modulation frequencies are used on an ILS approach?
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What audio frequency does the inner marker utilize?
What audio frequency does the inner marker utilize?
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What is the angle on either side of the extended centerline for a CAT 1 ILS at 17 nm that results in reverse sense indications?
What is the angle on either side of the extended centerline for a CAT 1 ILS at 17 nm that results in reverse sense indications?
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What is the maximum safe ‘fly-up’ indication on the glide path needle with a 5-dot indicator?
What is the maximum safe ‘fly-up’ indication on the glide path needle with a 5-dot indicator?
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Using the 1 in 60 rule, what is the approximate height of an aircraft 3 nm from touchdown on a 2.9° glide slope?
Using the 1 in 60 rule, what is the approximate height of an aircraft 3 nm from touchdown on a 2.9° glide slope?
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What is the rate of descent in ft/min for a 3° glide slope at a ground speed of 140 kt?
What is the rate of descent in ft/min for a 3° glide slope at a ground speed of 140 kt?
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What VHF frequency range does the ILS localiser transmit between?
What VHF frequency range does the ILS localiser transmit between?
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The ILS localiser signal is made up of two lobes that are on which of the following?
The ILS localiser signal is made up of two lobes that are on which of the following?
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What is the audio frequency of the outer marker and its cockpit light color?
What is the audio frequency of the outer marker and its cockpit light color?
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In which band does the ILS glide path operate?
In which band does the ILS glide path operate?
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What is the typical range and audio frequency of the middle marker?
What is the typical range and audio frequency of the middle marker?
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What is the maximum glide path angle above which accurate signals cannot be guaranteed?
What is the maximum glide path angle above which accurate signals cannot be guaranteed?
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Study Notes
ILS Systems Overview
- Category III ILS provides accurate guidance down to the runway surface.
- The Outer Marker transmits on 75 MHz, modulated by Morse at two dashes per second.
- An aircraft on a 3-degree glide path reduces ground speed from 150 kt to 120 kt, decreasing the rate of descent by approximately 50 FT/MIN.
Glide Path and Descent Rates
- A 10 kt decrease in ground speed on a 3-degree glide path requires a decrease in the aircraft's rate of descent by 50 FT/MIN.
- For a 3.25-degree glide slope at a ground speed of 140 kt, the approximate rate of descent is 800 FT/MIN.
- Maintaining a 3-degree glide path at 120 kt requires a rate of descent of about 600 FT/MIN.
- Each dot on a five-dot display represents an approximate angular deviation of 0.5 degrees.
Indications and Marker Beacons
- The ILS outer marker features a blue light and emits a low-pitched 400 Hz modulated tone.
- The middle marker is identified audibly by alternate dots and dashes with an amber light flashing.
- The identification of the outer marker consists of low-pitched dashes accompanied by a blue light.
Operational Characteristics
- The ILS sensitive area is restricted when category II/III operations are in progress.
- Localiser coverage extends to a distance of 17 nm, with an angle coverage of approximately 35 degrees on either side of the centreline.
- Specific frequencies are used for each ILS element, with localiser frequencies typically ranging around 108-112 MHz.
False Glide Paths and Interference
- ILS can experience false glide paths due to multiple lobes in radiation patterns.
- False beams are primarily found above the correct glide path, presenting a risk during approaches.
- Marker beacons do not interfere with each other as they operate on different modulation frequencies.
Descent Calculations
- Using the 1 in 60 rule, height can be calculated for various glide paths and distances from the touchdown point.
- The height of an aircraft 4.5 NM from touchdown on a 3-degree glide path is approximately 1370 ft.
Instrument Landing System (ILS) Frequencies
- The glide slope transmits in the UHF band, while marker beacons operate on 75 MHz.
- The modulation frequencies for localiser signals are 90 Hz and 150 Hz.
- The amplitude modulation for the outer marker is 400 Hz with a blue light indication.
Approach Procedures and Navigation
- An HSI must have its course set to the localiser course for correct navigation during ILS approaches.
- Pilots must correct their flight path based on modulation signals received; more 90 Hz indicates a left and down adjustment.
- The maximum safe deviation below the glide path during approach is typically half scale deflection.
Miscellaneous
- The upper vertical coverage of the localiser should be not less than 7 degrees above the horizontal plane.
- ILS equipment and markers are identified through synchronized audio and visual signals in the cockpit.
- Localiser back beams should only be used if there is a published procedure due to potential risks associated with false indications.### ILS Localiser Coverage and Specifications
- Cat I ILS localiser azimuth and area coverage: 35° at 17 nm, 10° at 25 nm.
- ILS glide path is effective for maintaining a 32.5° glide slope at 140 knots; the approximate rate of descent is 800 fpm.
- Back beams from ILS may be received when approaching from behind the localiser aerial.
- Reverse sense indications can occur outside protected coverage on the approach side of the localiser.
- Typical localiser frequency characteristics include A8W at 110.30 MHz.
Glide Path Coverage and Minima
- ILS glide path elevation coverage is precise from 1.35° to 5.25° for a 3° glide path.
- Marker colours during an ILS approach follow: blue, amber, white.
- ILS localiser is usually positioned 300 m from the upwind end of the runway.
- Outside ILS coverage, CDI indications are unreliable in azimuth and elevation.
Frequency Bands and Navigation
- ILS glide path frequency operates in the UHF band, specifically in the decimetric range.
- For CAT I ILS, minima are specified as: Height 200 ft; RVR 550 m.
- CAT II ILS minima: Height 100 ft; RVR 300 m.
- ILS outer marker emits 400 Hz and illuminates a blue light.
Approach and Indications
- Indicators reveal approach status: If high, the glide path needle shows above; if low, it indicates below.
- The maximum "fly-up" indication on the glide path needle is 2.5 dots.
- At the outer marker, an ILS approach at a 3° slope requires a rate of descent of 710 ft/min at a ground speed of 140 knots.
- Errors in ILS localiser beams are primarily due to ground reflections.
Marker Frequencies and Operations
- Middle marker is typically located at 1 km, with an audio frequency of 1300 Hz, illuminating an amber light.
- Outer marker emits 400 Hz audio frequency.
- ILS localiser signals comprise two lobes on the same frequency but utilize different modulations.
Glide Path Angle and Coverage
- The ILS provides reliable navigation within specified angles: generally, 0.7° above and below the glide path, with 8° on either side of the localiser.
- Accurate glide path signals are unreliable beyond 1.75 times the glide path angle.
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Description
Test your knowledge of Category III ILS systems and the Outer Marker frequency used in Instrument Landing Systems. This quiz is essential for aspiring pilots and those preparing for the ATPL and IR exams. Challenge yourself and see how well you understand these critical aviation concepts.