02 Radio Aids Flashcards
ATPL RADIO
Microwave Landing Systems (MLS) allow the aircraft to fix its position accurately in three dimensions by means of:
Timing the passage of two scanning beams co-located with DME
According to ICAO 8168, what is regarded as the maximum safe deviation below the glide path during ILS approach?
Half scale deflection.
The coverage of the ILS localiser at 17 NM is guaranteed up to an angle either side of the extended centreline of:
35°
The heading rose of an HSI is frozen on 200°. Lined up on the ILS of runway 25, the localizer needle will be:
centred
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The indications of the localiser deviation bar is independent of any course selection both on OBIs and HSIs. The localiser indication is based on the difference in depth of modulation alone, i.e. any indication is purely based on any angular deviation from the runway centreline by the aircraft.
Therefore, the deviation bar will be centred whenever the aircraft is on the localiser centreline regardless of either compass indication or course selection.
ILS is subject to false glide paths resulting from:
multiple lobes of radiation patterns in the vertical plane
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The ILS glidepath is subject to false indications due to multiple lobes radiating in the vertical plane (for the localiser the multiple lobes are radiating in the horizontal plane). All false glidepaths will be found above the nominal glidepath.
An aircraft, on a heading of 180°M is on a radial of 270°M from a VOR. The bearing you should select on the OMNI bearing selector to centralise the VOR/ILS left/right deviation needle is:
090°
Distance Measuring Equipment (DME) operates in the:
UHF band and is a secondary radar system.
…………………….
Note: Currently allocated frequencies are in the range 962 - 1213 MHz
With respect to the monitoring system of a VOR which statement is correct?
Failure of the VOR station to stay within the required limits can cause the removal of identification and navigation components from the carrier or radiation to cease.
Locators are:
- High powered NDBs used for en route and airways navigation.
- Low powered NDBs used for airfield or runway approach.
- Beacons with a usually range of 10 to 250 NM.
- Beacons with a usually range of 10 to 25 NM.
The combination regrouping all the correct statements is:
2 and 4.
The OUTER MARKER of an Instrument Landing System (ILS) facility transmits on a frequency of:
75 MHz and is modulated by morse at two dashes per second
……………………….
The outer marker (OM) is identified by a blue flashing light and a 400 Hz tone transmitted as continuous dashes.
The middle marker (MM) is identified by an amber flashing light and a 1300 Hz tone transmitted as alternating dots and dashes.
The inner marker (IM) is identified by a white flashing light and a 3000 Hz tone transmitted at 6 dots per second
What is the function of the Echo Protection Circuit (EPC)?
The EPC has to detect if the interrogator-receiver has been locked on, by reflected pulse-pairs.
To avoid inaccuracies that may be caused by coastal refraction the pilot should take an ADF bearing when:
the aircraft is located in a position where a straight line to the NDB will be perpendicular to the coastline
An aircraft is flying on a MH of 210°.
The magnetic variation at the VOR is 5°W and at the aircraft 10°W.
Which VOR-RMI corresponds to the indications on the HSI shown on the Annex?
Figure B
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The course selected on the course selector is 200º and with that selection the indicator shows a TO indication and a fly right indication. As there is a TO indication, the aircraft is on an inbound course that is 5º to the left of the selected course (210º), i.e. 210º + 5º = 215º.
The aircraft is on radial 215º – 180º = 035º.
The RMI will indicate the aircraft heading (210º) and the tail of the needle will point at the present radial, i.e. 035º, and the head of the needle will point towards the station along that radial, i.e. a course of 035º + 180º = 215º.
Which range facility associated with the ILS may be identified by a two-letter identification group?
Locator.
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Locator beacons are low power NBDs with a range of 10-25 nm that can be used as part of an ILS approach providing range from the runway based on station passage.
Locator beacons are recognised by a two letter identifier code.
If the (angular) displacement of an aircraft (with respect to the localiser centerline) doubles (e.g. from 1° tot 2°) the measured Difference in Depth of Modulation
doubles.
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The amount of difference in depth of modulation (the difference in signal strength of the 90 Hz and 150 Hz signals compared to each other) is proportional to the angular displacement from the localiser centreline or optimal glideslope.
In an ILS, concerning the localiser principle of operation, the difference in depth of modulation (DDM) will:
increase with displacement from the centerline.
………………….
The amount of difference in depth of modulation (the difference in signal strength of the 90 Hz and 150 Hz signals compared to each other) is proportional to the angular displacement from the localiser centreline or optimal glideslope.
Given: Magnetic heading 280° VOR radial 090° What bearing should be selected on the omni-bearing selector in order to centralise the VOR deviation needle with a “TO” indication?
270°
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The deviation bar of an omni-bearing indicator (OBI) will be centralised when the omni-bearing selector (OBS) is set to either the present course to or radial from the VOR. The TO/FROM indicator will indicated whether the selected course will take the aircraft towards or away from the station. Any indication on the OBI is irrespective of the aircraft heading.
If the aircraft is on radial 090º (i.e. East of the station), the deviation bar will be centred when either 090º or 270º is selected but only 270º will give a TO indication as this track will take the aircraft towards the station.
Middle marker beacons of an ILS transmit at:
75 MHz.
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The system frequency for marker beacons is 75 MHz, i.e. in the VHF band, regardless of whether it is outer, middle or inner/airway marker. Their morse code and tone (and associated colour) will be different but due to their limited range, they will not interfere with each other.
What is measured in order to establish aircraft position in relation to the localiser beam on an ILS?
The difference in depth between the 90 Hz modulation and the 150 Hz modulation.
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In order to determine any angular displacement from the localiser centreline, the localiser receiver will use the difference in depth of modulation between the 90 Hz and 150 Hz signals transmitted by the localiser transmitter.
If the signals are of equal strength, i.e. there is no difference in depth of modulation the aircraft is on the localiser centreline.
Two aircraft are located on (arbitrary) different radials but at equal distances from a VOR-station. Which statement is true?
At a certain moment of time the phase of the reference signals is equal and the phase of variable signals is unequal for both aircraft.
On an ILS approach, the glidepath needle is fully down. How much deflection does this indicate?
0.7°
…………………
Full scale deflection for the glideslope display indicates 0.7º displacement from the optimal gldeslope.
What are the modulation frequencies of the two overlapping lobes that are used on an ILS approach?
90 HZ 150 Hz
A radar which employs an interrogator/transponder principle is:
Secondary Surveillance Radar
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The Interrogator / Transponder principle involves:
- The Interrogator transmitting an interrogation signal, using its own power;
- The Transponder transmitting a reply signal, again using its own power.
In which frequency band does an ILS glide slope transmit?
UHF
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The glideslope transmit in the UHF band (329.15 MHz – 335 MHz).
Which of the following will give the most accurate calculation of aircraft ground speed?
A DME station sited on the flight route
…………………
The DME can provide groundspeed based on the rate of change of distance, however, this will only be correct when flying directly towards or away from the station, i.e. the station is situated on the flight route.
What causes the so-called night effect?
A change in the direction of the plane of polarisation due to reflection in the ionosphere.
……………………..
The night effect will alter the polarisation of the signal when it is refracted in the ionosphere. This change of polarisation will contaminate the surface wave coverage area reducing the effectiveness of the loop antenna thus effectively reducing the range of the NDB.
With respect to the principle of distance measurement using DME can be stated that:
- the interrogation signal is transmitted on the same frequency as the reply signal.
- the DME station always has a transponder delay of 50 milliseconds.
- the time between the pulse pairs of the interrogation signal is at random.
- In the search mode more pulse pairs per second are transmitted than in the tracking mode.
Which of the above given statements are correct?
3 and 4
When flying at 6000 feet above ground level, the DME indicates 5 NM. What is the horizontal distance from the aircraft to overhead the DME?
4.9 NM
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DME indicates Slant Range (direct line of sight distance) to the ground station.
Slant Range can be calculated using Height and Ground Range.
In this case, the Slant Range is given as 5 NM.
Similarly, Ground Range can be calculated using Slant Range and Height.
The aircraft is at 6 000 ft above the DME station.
Aircraft Height = 6 000 ft / 6 000 ft
Aircraft Height = 1 NM
Using Pythagoras’ Theorem, the Ground Range can now be calculated.
Ground Range = v(Slant Range² - Height²)
Ground Range = v(5² - 1²)
Ground Range = v(25 - 1)
Ground Range = v24
Ground Range = 4.9 NM
Answer: 4.9 NM
The DME Line Of Position is a circle with radius:
the slant range and centre the DME-station.
……………………….
Drawing a circular position line based on a DME distance will be based on the slant range as the DME distance as indicated by the DME unit is the direct line of sight distance to the station which is a combination of the ground distance and the height of the aircraft above the station.
The circular position line will be centred on the ground station.
A radio beacon has an operational range of 10 NM. By what factor should the transmitter power be increased in order to achieve an operational range of 20 NM?
4
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If you double transmitter power you will increase your range by the square root of 2. Which is 1.414 time the range.
therefore 4 x pwr = 10nm x 1.414 = 14.14 x 1.414 = 19.99nm
The aircraft DME receiver is able to accept replies to its own transmissions and reject replies to other aircraft interrogations because:
the time interval between pulse pairs is unique to that particular aircraft
Concerning the glidepath principle of operation in an ILS, the difference in depth of modulation (DDM) will:
increase with displacement above or below the glidepath.
………………….
The amount of difference in depth of modulation (the difference in signal strength of the 90 Hz and 150 Hz signals compared to each other) is proportional to the angular displacement from the localiser centreline or optimal glideslope.
Why can DME stations only send out distance information to approximately 100 aircraft at a time?
A DME ground station is only able to process 2700 ppps.
Which of the following is true about the ADF?
It does not have a signal failure warning flag.
A cumulonimbus cloud in the vicinity of an aeroplane can cause certain navigation systems to give false indications. This is particularly true of the:
ADF
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The ADF is the system that is most sensitive to static interference, and a nearby thunderstorm may render the ADF useless as it turns into a lightning finder.
An aircraft is flying on a MH of 210°. The magnetic variation at the VOR is 5°W and at the aircraft 10°W. According to the HSI shown at the Annex the aircraft is on radial:
025
……………
The heading of the aircraft is irrelevant in order to establish the position on a HSI.
The course selector is set to 200º and with a TO indication this means that the selected radial is the reciprocal, i.e. 200º – 180º = 020º.
As the deviation bar is showing half scale deviation to the right, the aircraft is 5º to the left of the selected radial when facing the VOR. Therefore, the aircraft is on radial 020º + 5º = 025º.
The basic principle of operation of the ILS is the difference in depth of modulation (DDM) between the 90 Hz and 150 Hz lobes. A DDM of zero indicates:
- The higher tone lobe is received at a higher strength than the lower tone lobe;
- On the localiser centreline;
- The aircraft is on the Glide Path;
- A balance between modulations.
The combination that regroups all the correct statements is:
2,3,4
On which of the following displays are you able to get a direct read-out (no calculation is necessary from the pilot) of the magnetic bearing from the aircraft to the NDB?
Moving card ADF and RMI.
…………………
The RMI will automatically indicate the magnetic bearing to the NDB provided it shows the correct magnetic heading from the compass system.
An RBI with a rotating card can indicate the magnetic bearing to the NDB provided the compass card is aligned with the aircraft compass at all times.
NDB is the abbreviation for:
Non Directional Beacon.
Which of the following is true in respect of using ILS back-beam approach procedure?
When using an HSI you must set the course arrow to the localizer front-beam course.
Which one of the statements below is correct regarding the DME?
The DME operating frequencies are in the UHF frequency band.
………………………………
The DME operates in the UHF band.
The DME will indicate the direct distance between the aircraft and the station, also known as the slant range, i.e. a combination of the ground distance and the height of the aircraft above the station.
A DME may be co-located with a VOR, ILS or NDB or may be a stand alone installation.
If obtaining a fix from two DME stations the position fix will be ambiguous as there are two possible positions with the circular position lines intersecting at two places.
Which statement is true about the use of the Doppler effect in a Doppler VOR?
The Doppler effect is used to create a signal which is received by the aircraft’s VOR-receiver as a frequency modulated signal.
An ILS marker beacon operates in the:
VHF band.
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The system frequency for marker beacons is 75 MHz, i.e. in the VHF band, regardless of whether it is outer, middle or inner/airway marker. Their morse code and tone (and associated colour) will be different but due to their limited range, they will not interfere with each other.
The ILS marker with an aural frequency of 3000 Hz is the:
inner marker (if available).
……………………
The outer marker (OM) is identified by a blue flashing light and a 400 Hz tone transmitted as continuous dashes.
The middle marker (MM) is identified by an amber flashing light and a 1300 Hz tone transmitted as alternating dots and dashes.
The inner marker (IM) is identified by a white flashing light and a 3000 Hz tone transmitted at 6 dots per second
Transmissions from VOR facilities may be adversely affected by:
uneven propagation over irregular ground surfaces
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An error that is associated with VORs is the effect of the surface causing bending or scalloping of the signals.
Static interference, quadrantal error and night effect are all errors mainly associated with NDBs.
What is the colour sequence when passing over an Outer, Middle and Inner Marker beacon?
blue - amber - white
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The outer marker (OM) is identified by a blue flashing light and a 400 Hz tone transmitted as continuous dashes.
The middle marker (MM) is identified by an amber flashing light and a 1300 Hz tone transmitted as alternating dots and dashes.
The inner marker (IM) is identified by a white flashing light and a 3000 Hz tone transmitted at 6 dots per second
The ILS marker with an aural frequency of 400 Hz is:
outer marker.
Given: VOR station position N61° E025°, variation 13°E; Estimated position of an aircraft N59° E025°, variation 20°E. What VOR radial is the aircraft on?
167°
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Since the aircraft is on the same meridian as the VOR (
Since the aircraft is South of the VOR, the true bearing of the aircraft from the VOR is 180º (aircraft and VOR on the same meridian with the VOR at a higher latitude (N61) the aircraft at a lower latitude (N59)).
A VOR radial is defined as the magnetic bearing of the aircraft from the station when applying the variation at the station, and since the variation at the station is 13ºE, the magnetic bearing of the aircraft is 180ºT ± 13E = 167ºM. Therefore, the aircraft is on radial 167.
Since the aircraft is on the same meridian as the VOR (E01000), the aircraft will either be due North or South of the VOR. With the VOR at N4500 and the aircraft at N4400, the aircraft is South of the VOR, i.e. the true bearing of the aircraft from the VOR is 180º.
A VOR radial is defined as the magnetic bearing of the aircraft from the station when applying the variation at the station, and since the variation at the station is 10ºW, the magnetic bearing of the aircraft is 180ºT ± 10ºW = 190ºM. Therefore, the aircraft is on radial 190º.
The ILS Marker beacons use the following wavelengths:
Metric
What is true about the range of an NDB?
It is affected by the power of the transmitter.
If a ground VDF controller passes a bearing thus: “Your true bearing is 256°, Class alpha”, this means:
QTE accurate to +/-2°
‘Night Effect’ which causes loss of signal and fading, resulting in bearing errors from NDB transmissions, is due to:
skywave distortion of the null position and is maximum at dawn and dusk
……………………….
The night effect is greatest at dusk and dawn and is caused by increased presence of sky waves within the area where the surface wave is present. The sky wave will mix with the surface wave and the resultant is a less defined or altered null position making obtaining an accurate bearing more difficult. This interference is not affected by the direction from the NDB to the aircraft.
An aircraft is flying on the 245 radial with a MH of 250º. On the HSI the CRS is set to 060.
Which HSI shows the correct indications?
Figure A
Which of the following list use the VHF band: 1. Locator. 2. Localiser. 3. Outer Marker. 4. Glide path. The combination that regroups all the corrects statements is:
2 and 3.
…………..
The localiser transmit in the VHF band (108.10 MHz – 111.95 MHz).
The outer marker transmit in the VHF band (75 MHz).
The glideslope transmit in the UHF band (329.15 MHz – 335 MHz).
The locator transmit in the LF/MF band (190 kHz – 1750 kHz).
The ILS marker identified visually by a white light flashing is the:
inner marker.
In flight, a pilot can improve the range of his transmission with a VDF operator by:
increasing altitude.
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As VDF operates in the VHF band (normal ATC communications), the signals will propagate as space waves, i.e. requiring line of sight between the transmitter and the receiver. The best way to improve range is therefore to increase the altitude of the transmitter.
On the RMI the tip of a VOR needle indicates 060. With the CRS set on 055 the indications on the HSI are
TO, half scale deflection to the right.
An ADF indicator with a manually rotatable card:
the card should be rotated so that the aircraft heading is at the top of the indicator.
The Microwave Landing System (MLS) uses the following wavelengths:
centimetric.
Night Effect in an ADF may cause:
Fluctuating indications of the needle on the RMI.
……………………………
One result of the night effect is the inability for the ADF to obtain a defined bearing which will result in the needle fluctuating, also known as a hunting needle.
In which frequency band does the Microwave Landing System (MLS) operate?
SHF
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The MLS transmit in the SHF band (5031 MHz – 5091 MHz).
An aircraft is flying on the 050 radial with a MH of 250º. On the CDI the CRS is set to 060.
Which CDI shows the correct indications?
Figure C
The basic principle of operation of the ILS is the difference in depth of modulation (DDM) between the 90 Hz and 150 Hz lobes.
A DDM of zero indicates:
- the higher tone lobe is received at a higher strength than the lower tone lobe.
- the exact runway centreline.
- the aircraft is on the glidepath.
- a balance between modulations.
When there is no difference in depth of modulation, the strength pf the 90 Hz and 150 Hz signals are equal, i.e. the aircraft is on the localiser centreline and the optimum glideslope.
An aircraft is “homing” to a radio beacon whilst maintaining a relative bearing of zero. If the magnetic heading decreases, the aircraft is experiencing:
right drift
Using the attached image:
The letters QTX and adjacent symbol indicate:
VORTAC
The quadrantal error of an ADF
is caused by the refraction from the aircraft’s fuselage and is compensated for.
Which one is the most correct statement regarding the range of the DME system?
Range within “line of sight”, and maximum 200 NM.
If the number of pulse pairs received by a DME responder exceeds the maximum number possible, which aircraft will be denied first?
The aircraft from which the weakest pulse pairs are received.
A typical DME frequency is:
1000 MHz.
Which marker has a higher audio tone?
Inner marker.
What is the effect of FM broadcast stations that transmit on frequencies just below 108 MHz on the performance of ILS.
These transmissions may interfere with the ILS localizer signal which may lead to erroneous localizer deviation indication.
What actually happens in the ADF receiver when the BFO position is selected?
The BFO circuit imposes a tone onto the carrier wave to make the NDB’s ident audible.
The Glide Path antenna is located on the side of the runway approximately:
300 m beyond the threshold.
…………………………
The glideslope antenna is normally placed alongside the runway around 300 m from the threshold of the landing runway.
Regarding the ILS back course approach at Daytona Beach, which instrument (if any) can you set the back course on to show the correct indication?
HSI only
On an ILS approach, the localiser needle is fully over to the left. How much deflection does this indicate?
2.5°
………………….
Full scale deflection for the localiser indication is 2.5º and for the glidepath indication 0.7º,
When the term “radial” is used in reference to VOR it means:
When the term “radial” is used in reference to VOR it means:
…………………
When referring to a VOR, a ‘radial’ is the magnetic bearing FROM the station
Which frequency band is used by VOR transmissions?
VHF
…………
VORs transmit in the VHF frequency band (hence the name VHF omni-range) (30 MHz – 300 MHz) using the frequency band 108.00 MHz – 117.95 MHz.
The ILS marker identified visually by an amber light flashing is the:
middle marker.
During a flight at FL 260, a pilot does not receive any DME distance indication from a DME station located approximately 220 NM away. The reason for this is that the:
Aeroplane is below the line of sight altitude.
You are in an aircraft at FL 370. What is your slant range to a beacon 15nm away at a height of 1,000ft?
16 NM
The back beam of a localiser antenna:
Can be used as a published non-precision approach.
Which of the following alternatives is correct regarding audio- and visual signals in the cockpit when passing overhead a middle marker?
Audio: 1300 Hz, alternating dots and dashes. Visual: Amber light flashes.
The Distance Measuring Equipment (DME) uses the following wavelengths:
decimetric.
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The DME frequency range is 960 MHz to 1215 MHz. Using a medium frequency of 1100 MHz, the wavelength is:
Wavelength (?) = speed of light (c) ÷ frequency (f) = 300 000 000 m/s ÷ 1 100 000 000 Hz = 0.273 m
This is in the decimetric band (0.1 m – 0.9 m).
Your aircraft is heading 075°M. The OBI is set to 025°. The VOR indications are ‘TO’ with the needle showing right deflection. Relative to the station, you are situated in a quadrant defined by the radials:
205° and 295°
On an ILS approach, when flying overhead the inner marker (if available) the colour of the flashing light will be:
white.
Given:
True heading 066° Variation 4°W Drift angle 12° Relative bearing to the station 070° What is the true bearing of the aircraft from the station?
316°
Factors liable to affect most NDB/ADF system performance and reliability include:
static interference - night effect - absence of failure warning system
A pilot flying an aircraft at FL 80, tunes in a VOR which has an elevation of 313 m. Given ISA conditions, what is the maximum theoretical distance at which a pilot might expect to receive the VOR signals?
151 NM
Range of VDF depends on:
- Loudness of the voices of the pilot and the operator when transmitting.
- Power of airborne and ground transmitters.
- Power of pilot voice when transmitting.
- . Aircraft altitude and ground transmitter elevation
The combination regrouping all the correct statements is:
2 and 4.
In accordance with Doc 8168, a pilot flying an NDB approach must achieve a tracking accuracy within….. of the published approach track.
+/-5°
An aircraft is flying at FL 240. The DME indication (without altitude correction) is 8 NM.
Calculate the ground distance to the beacon:
7.0 NM
…………………….
Convert altitude into nautical miles
FL240 = 24,000 ft
24,000 ft / 6,080 ft = 3.95 nm
DME Range² = Ground Range² + Height²
8² = Ground Range² + 3.95²
64 = Ground Range² + 15.58
Transpose formula to solve Ground Range
Ground Range² = 64 - 15.58
Ground Range² = 48.42
Ground Range = v48.42
Ground Range = 6.96 nm
The closest answer is 7.0 nm
Where, in relation to the runway, is the ILS localiser transmitting aerial normally situated?
On the non-approach end of the runway about 300 m from the runway on the extended centreline
The MLS uses a principle of operation based on:
Time reference scanning beam.
The azimuth transmitter of a Microwave Landing System (MLS) provides a fan-shaped horizontal approach zone which is usually:
+/- 40° of the runway centre-line.
Range of VDF depends on: 1. Line of sight formula 2. Power of transmitters 3. Intervening high ground. The combination regrouping all the correct statements is:
1, 2 and 3.
An aircraft is maintaining an airway centreline of 000° defined by a VOR ahead of the aircraft. Variation at the VOR is 5°E. With 60 NM to go to the VOR the QDM is 004°. The aircraft’s position relative to the airway lateral boundary is:
1 NM inside the airway southern boundary
The design requirements for DME-N stipulate that, at a range of 100 NM, the maximum systematic error should not exceed:
+ or - 1.5 NM
………………..
DME-N is calibrated to operate to an accuracy of ±0.25 nm + 1.25% of the DME distance.
Accuracy at 100 nm = ±0.25 nm + (100 nm x 1.25%) = ±1.5 nm
The VOR system is limited to about 1° of accuracy. One degree at 200 NM represents a width of:
3.5 NM
…………………..
This question is really a 1 in 60 rule question rather than a VOR issue.
Hopefully you will recall the 1 in 60 formula:
Track Error Angle = (dist off track x 60) / range
Therefore: 1 = (dist off track x 60) / 200
Therefore: dist off track = 200 / 60 = 3.33nm
The time taken for the transmission of an interrogation pulse by a Distance Measuring Equipment (DME) to travel to the ground transponder and return to the airborne receiver was 2000 micro-second. The slant range from the ground transponder was:
158 NM
Which of the following errors is associated with the use of VOR?
Scalloping.
A localiser must provide a minimum horizontal coverage to a distance of:
17 NM over a sector of 35° each side of the centre line.
An en-route DME and VOR that have the same Morse code identifier are associated and are:
Within 2000 feet of each other.
Which statement is correct for tracking towards an NDB in an area with constant wind and constant magnetic variation?
The Relative Bearing of the NDB should be equal (in magnitude and sign) to the experienced Drift Angle.
While performing an ILS approach, the maximum safe “fly-up” indication of the glide path needle (assuming a 5-dot indicator) is:
2.5 dots.
……………………….
While performing an ILS approach, the maximum safe “fly-up” indication of the glide path needle (assuming a 5-dot indicator) is 2.5 dots.
An ILS category II ground installation is one that is capable of providing guidance to a height of:
15 m above the horizontal plane containing the threshold.
On final on ILS approach, at 0,6 NM from the threshold, which marker are you likely to hear?
The middle marker.
A VOR indication of 240° FROM is given. Variation at the aircraft is 9°W and at the VOR is 7°W. What is the heading (assume zero wind) to reach the station:
053° (T)
………………..
This is a very poorly worded question and a number of assumptions have to be made:
(a) The selected course on the Course Deviation Indicator (CDI) is 240°;
(b) The deviation bar is centred.
Given these assumptions, the aircraft will be positioned on the R-240° radial and in order to fly directly to the station the aircraft would have to fly along a track, which is the reciprocal to this radial.
The bearing of the radial is measured in degrees magnetic at the ground station; that being the case, any application of magnetic variation is applied at the station.
Reciprocal of R-240° = 240°M - 180° = 060°M inbound
Then, apply magnetic variation ( as measured at the ground station)
Variation West Magnetic Best (True is less)
060°M - 7°W = 053°T
True Track = 053°T
Which of these markers has the highest audible frequency?
Inner
…………………..
The outer marker (OM) is identified by a blue flashing light and a 400 Hz tone transmitted as continuous dashes.
The middle marker (MM) is identified by an amber flashing light and a 1300 Hz tone transmitted as alternating dots and dashes.
The inner marker (IM) is identified by a white flashing light and a 3000 Hz tone transmitted as continuous dashes.
What is a VDF referenced to?
Magnetic north at the station.
……………………
The bearing of the aircraft is measured at the VDF station and will be referenced to true or magnetic North at the station.
A VOR is sited at position 58°00’N 073°00’W where the magnetic variation equals 32°W. An aircraft is located at position 56°00’N 073°00’W where the magnetic variation equals 28°W. The aircraft is on VOR radial:
212
Given:
Aircraft position 36°15’S 178°E, magnetic variation 21°W, FL 310.
UEB VOR/DME position 36°15’S 178°W, magnetic variation 21°E.
In order to read the most accurate ground speed on the DME receiver from his present position, the pilot must fly which UEB radial?
249°
Concerning the localiser principle of operation in an ILS, the needle of the aircraft indicator is centred when the difference in depth of modulation (DDM) is:
null.
……………..
When the aircraft is on the localiser centreline (the localiser deviation bar is centred) the strength of the 90 Hz and 150 Hz signals are the same, i.e. there is no difference in depth of modulation.
Assuming a five dot display on either side of the ILS localiser cockpit display, what is the angular displacement of the aircraft from the localiser centreline when the CDI is deflected 2 dots to the right?
1.0° to the left.
Which of the following statements about the scalloping (path deflection) of VOR-radials, in relation to the accuracy of navigation using a VOR/DME RNAV-system, is correct?
Scalloping has a negative effect on the accuracy of navigation.
What is the function of a FM-immune filter?
To make the ILS-localizer receiver less susceptible to interference from commercial FM-stations (radio and television).
At reference.
An NDB is located 10 NM inland and you are flying along the coastline (see picture) and experience shore/coastal effects. In which sectors do you expect minimum errors?
in sectors A & B
A Cat III ILS glidepath transmitter provides reliable guidance information down to:
the surface of the runway
The three main components of VOR airborne equipment are
Receiver, Antenna, Display
What is the approximate maximum theoretical range at which an aircraft at FL130 could receive information from a VDF facility which is sited 1024 FT above MSL?
180 NM
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VHF direction finding (VDF) signals propagate as space waves, i.e. line of sight. The maximum theoretical range is calculated using the following formula:
VHF range = 1.23 x (√height of the station + √height of the aircraft)
VHF range = 1.23 x (√height of the station + √height of the aircraft) = 1.23 x (√1024 ft + √13 000 ft) = 179.6 nm
Allocated frequencies for NDB are:
190 kHz to 1750 kHz.
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The frequency band for the NDB/ADF system is 190 to 1750 kHz.
An aircraft is flying a 3° glidepath and experiences a reduction in groundspeed from 150 kt at the outer marker to 120 kt over the threshold. The effect of this change in groundspeed on the aircraft’s rate of descent will be a decrease of approximately:
150 FT/MIN
A DME in tracking mode subsequently experiences a reduction in signal strength will switch the equipment in the first instance to:
memory mode
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If the DME receiver lose its signal it will switch to memory mode (maintaining the current rate of change of distance) for a finite amount of time. If the signal loss is longer than the defined time the DME will indicate a loss of signal.
Two aircraft are located on the same radial but at (arbitrary) different distances from a VOR-station. Which statement is true?
At a certain moment of time, both the phase of the reference signals and of the variable signals are equal for both aircraft.
An aircraft is flying on the 170 radial with a MH of 315º. On the HSI the CRS is set to 180.
Which HSI shows the correct indications?
Figure C
The maximum theoretical range at which an aircraft at FL230 may receive signals from a VOR facility sited at mean sea level is:
190 NM
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The maximum theoretical range of a VOR is calculated using the following formula:
VHF range = 1.23 x (vheight of the station + vheight of the aircraft)
VHF range = 1.23 x (vheight of the station + vheight of the aircraft) = 1.23 x (v0 ft + v23 000 ft) = 186.5 nm
Category II operation is:
A precision instrument approach and landing, with a DH lower than 200ft but not lower than 100ft, and an RVR not less than 350m.
An aircraft is situated at 30°N - 005°E with a magnetic variation of 10°W. A VOR is located at 30°N - 013°E with a magnetic variation of 15°W. The aircraft is situated on the VOR radial:
286°
The tilt angle of an Airborne Weather Radar (AWR) is set at +2°. If the beam width is 4° and the range of the cloud is 40 NM, what is the approximate height of the cloud above or below the aircraft when the weather return from the cloud just disappears from the screen?
At the same height as the aircraft.
Which statement about the errors and effects on NDB radio signals is correct?
The mountain effect is caused by reflections onto steep slopes of mountainous terrain which may cause big errors in the bearing.
Every 10 kt decrease in groundspeed, on a 3° ILS glidepath, will require an approximate:
decrease in the aircraft’s rate of descent of 50 FT/MIN
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Rate of descent in ft/min for a 3º glideslope can be found by multiplying the groundspeed by 5.
If the aircraft is flying slower, the rate of descent must be decreased in order to follow the same glideslope as when the speed was greater. The change in rate of descent can be found by substituting the actual groundspeed by the change in groundspeed.
Rate of descent = groundspeed x 5 = 10 kts x 5 = 50 ft/nm
108.35 MHz can only be:
an ILS frequency.
The effect of masking the DME antenna of the aircraft from the ground installation is that Interruption of reception of DME signals results in:
The Airborne installation switching to the memory mode for about 10 to 15 seconds.
MLS can minimise multi-path errors because:
the transmission can be interrupted to avoid reflection by stationary objects.
Which of the following components of the ILS are protected from interference by the FM-Immunity filters in NAV equipment?
Localiser only.
You are on a magnetic heading of 055° and your ADF indicates a relative bearing of 325°. The QDM is:
020°
The maximum safe deviation below the glide path during ILS approach (according to ICAO Doc 8168) is indicated by a half scale deflection on your instrument. What shall the pilot do if the indicated deflection is more than a half scale deflection?
Initiate a go-around.
Regarding ILS which of the following is true?
All markers transmit at 75 MHz.
The UHF band is assigned to the: 1. Locator. 2. Localiser. 3. Outer marker. 4. Glide path. The combination that regroups all the corrects statements is :
4.
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The glideslope transmit in the UHF band (329.15 MHz – 335 MHz).
The localiser transmit in the VHF band (109.10 MHz – 111.95 MHz).
The locator transmit in the LF/MF band (190 kHz – 1750 kHz).
The outer marker transmit in the VHF band (75 MHz).
What is the maximum theoretical range that an aircraft at FL150 can receive signals from a VOR situated 609 feet above MSL?
184 NM
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The maximum theoretical range of a VOR is calculated using the following formula:
VHF range = 1.23 x (vheight of the station + vheight of the aircraft)
VHF range = 1.23 x (vheight of the station + vheight of the aircraft) = 1.23 x (v609 ft + v15 000 ft) = 181 nm
‘Beam bends’ in the ILS approach path are:
slight curves that can be followed by large aircraft.
The OBS is set to 235°. The indications of the VOR are half scale deflection left and ‘to’. The aircraft is on the radial:
050°
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With the OBS set to 235º and a TO indication the aircraft is to the northeast of the VOR. If the deviation bar was centred the aircraft would on a radial that is reciprocal to the selection, i.e. 235º – 180º = 055º. With half scale “fly left” indication the aircraft is 5º to the right of the selected radial when facing the VOR, i.e. on radial 055º – 5º = 050º.
The shoreline/coastal effect is caused by refraction of the radio waves. What is one factor influencing the error of the bearing?
Flight altitude.
ILS Cat II equipment will permit instrument approaches down to:
DH 100 ft, RVR 300 m.
An aircraft is flying on the true track 090° towards a VOR station located near the equator where the magnetic variation is 15°E. The variation at the aircraft position is 8°E. The aircraft is on VOR radial:
255°
In which situation will speed indications on an airborne Distance Measuring Equipment (DME) most closely represent the groundspeed of an aircraft flying at FL400?
When tracking directly towards the station at a range of 100 NM or more
Which of the following radio aids provides a measurement of distance?
DME
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VOR = VHF Omni-directional Ranging Equipment
ADF = Automatic Direction Finder
VDF = VHF Direction Finder
DME = Distance Measuring Equipment
The indicated range from a DME station is:
slant range.
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The DME distance is the direct distance between the aircraft and the station, also known as the slant range, i.e. it is a combination of the ground distance and the height of the aircraft above the station.
A VOR is sited at position A (45°00’N, 010°00’E). An aircraft is located at position B (44°00’N, 010°00’E). Assuming that the magnetic variation at A is 10°W and at B is 15°W, the aircraft is on VOR radial:
190°
The ILS glide path is normally intercepted between from the runway threshold:
3 and 10 NM
An aircraft at 6400 FT will be able to receive a VOR groundstation at 100 FT above MSL at an approximate maximum range of:
110 NM
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The maximum theoretical range of a VOR is calculated using the following formula:
VHF range = 1.23 x (SQRTheight of the station + SQRTheight of the aircraft)
VHF range = 1.23 x (SQRTheight of the station + SQRTheight of the aircraft) = 1.23 x (SQRT100 ft + SQRT6400 ft) = 110.7 nm
Use the 1 in 60 rule to determine the approximate height of an aircraft 3 NM from touchdown on a 2.9° glide slope?
880 ft
ICAO specifications are that range errors indicated by Distance Measuring Equipment (DME), older than 01.01.1989, should not exceed:
+/-0.25 NM plus 1.25% of the distance measured.
The ILS outer marker modulation frequency is:
400 Hz.
An ADF is correctly tuned to an NDB station but the needle is “hunting” and the signal is fading and growing louder alternately. The reason for this is:
the required ground wave is being contaminated by sky waves
By using a random PRF the DME interrogator can:
Distinguish its own replies from those triggered by other aircraft
What approximate rate of descent is required in order to maintain a 3° glidepath at a groundspeed of 90 kt?
450 FT/MIN
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Rate of descent in ft/min for a 3º glideslope can be found by multiplying the groundspeed by 5.
Rate of descent = groundspeed x 5 = 90 kts x 5 = 450 ft/nm
The reason for using different frequencies for the airborne and ground equipment of a DME is
to prevent that DME interrogation pulse pairs being received by the aircraft after reflection on the earth surface.
Given: W/V (T) 230/ 20 kt, Var. 6E, TAS 80 kt What relative bearing from an NDB should be maintained in order to achieve an outbound course of 257°(M) from overhead the beacon?
188°
A VDF may be used
to provide the ATC controller with bearings of aircraft in the absence of radar.
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VDF (VHF direction finding) will sense the direction from which a signal arrives at the receiver antenna. This will provide the ATC officer with a bearing towards the aircraft assisting in establishing/confirming the aircraft position in the absence of radar. This bearing can also be used to provide steering information to assist the aircraft in flying towards the VDF station.
What type of antenna(s) must be used to obtain an ADF bearing?
Loop and Sense
The visual and aural indications of an ILS Outer Marker are:
A blue light and 2 dashes a second of a 400 Hz modulated tone.
The back CRS of an ILS may give:
non-precision approach guidance for the reciprocal of the main approach runway.
Full deflection on a glide slope indicator indicates that the aircraft is:
0.7° above or below the correct glide path.
The indication of a FROM/TO indicator of a CDI shift from TO/FROM
(and vice versa) when the value difference between selected course and
the measured radial passes in either direction:
090°
The transmission of the glide slope beacon is characterised by a:
UHF frequency with a minimum range of 10 NM.
Which of the following correctly describes the Instrument Landing System (ILS) localiser radiation pattern?
Two overlapping lobes on the same VHF carrier frequency
ILS produces:
a radiation pattern which is amplitude modulated by a 90 Hz and a 150 Hz signal.
What is true about the interrogation pulse transmission sequence of a DME system installed on board on aircraft?
It changes from interrogation to interrogation.
