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
………………………….
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
……………………….
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
……………..
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.
…………………
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.
…………….
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°
…………….
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.
………………..
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.
…………………..
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
………………..
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
………………
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
………………
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
…………..
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
……………..
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.
……………………..
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
………………..
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
…………………….
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°
……………..
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.
…………………
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
……………
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.
……………….
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
………………
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.
……………………..
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
………………….
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
………………..
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
……………………
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.
……………..
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
……………….
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°
…………..
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
……………
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.
……………….
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
………………….
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
……………….
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.
………………..
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.
If you are flying a back course ILS, you are flying a:
non precision approach on the reciprocal runway of the precision approach runway
What is the effect of multipath signals (coming from the same aircraft) at the Ground VHF Direction Finder station?
They may result in bearing errors.
The audio frequency modulation of the inner marker (if available) shall be keyed as follows:
6 dots per second continuously.
An aircraft, at FL 410 is passing overhead a DME station at mean sea level. The DME indicates approximately:
6.8 NM
…………………….
The DME will indicate the line of sight distance to the station, i.e. including a combination of ground distance and aircraft height above the station.
Directly overhead the station the DME will indicate the aircraft height in nm, 41 000 ft ÷ 6080 ft/nm = 6.7 nm
Which statement about the error and effects on NDB radio signals is correct?
The mountain effect is caused by reflections onto steep slope of mountainous terrain which may cause big errors in the bearing.
MLS not equipped with DME P:
provides basically the same approach capabilities as ILS.
The two signals transmitted by a conventional VOR ground station are 270° out of phase on magnetic:
west
An aircraft at FL 100 should be able to receive a VOR groundstation at 100 FT above MSL at an approximate maximum range of:
135 NM
For a conventional DME facility ‘Beacon Saturation’ will occur whenever the number of aircraft interrogations exceeds:
100
…………
Beacon saturation occurs when the number of interrogators exceeds 100. At this time the processing time for all interrogations add up to the time difference between each set of interrogation pulses from the DME unit in tracking mode, i.e. each DME unit will have its slot of the total capacity of the ground station.
Any more interrogators will not receive a reply from the ground station as here are no processing slots available.
What is the “Q” code for a true bearing from a VDF station?
QTE
……………..
The ‘Q Code’ for a true bearing from a VDF station is a ‘QTE’
Background Information
The following ‘Q Code’ descriptors are:
- QDM - Magnetic Bearing TO
- QDR - Magnetic Bearing FROM
- QUJ - True Bearing TO
- QTE - True Bearing FROM
Locators are:
LF/MF NDBs used as an aid for final approach.
…………………
A locator beacon is an NDB whose primary function is to act as an approach aid, therefore, a locator will often have a short range defined as 10 nm – 25 nm. Because of the shorter range the transmission power can be reduced.
Unless otherwise specified a radial is:
the magnetic great circle direction from the beacon.
………………..
A VOR radial is defined as the magnetic bearing from the station and the direction of the radial will follow a great circle track as radio waves follow great circle tracks.
In some cases the radial can be given with reference to true North (typically in areas close to the magnetic poles).
Which of the following is likely to have the greatest effect on ADF accuracy?
Interference from other NDBs, particularly at night
The design requirements for DME-P (equipment certified after 01 January 1989) stipulates that the total system error should not exceed:
0.2NM
……………
DME-P (precise) error for systems installed after 1 Jan 1989 should not exceed 0.2NM.
DME-N (narrow) error should not exceed 0.25NM + 1.25% of the measured distance.
The reason why pre take-off holding areas are sometimes further from the active runway when ILS Category 2 and 3 landing procedures are in progress than during good weather operations is:
aircraft manoeuvring near the runway may disturb guidance signals
Flying an ILS approach, the middle marker is positioned so as to be passed:
at about 200 ft AAL.
An aircraft is flying on a MH of 010°.
The magnetic variation at the VOR is 10°W and at the aircraft 12°W.
Which VOR-RMI corresponds to the indications on the CDI shown on the Annex?
Figure D
An airway 10 NM wide is to be defined by two VORs each having a resultant bearing accuracy of plus or minus 5.5°. In order to ensure accurate track guidance within the airway limits the maximum distance apart for the transmitter is approximately: (Disregard changeover point)
105 NM
……………
The greatest cross track error acceptable is 5nm off the airway centreline.
We assume that the aircraft flies out of one beacon and then switches over half way to home to the next beacon so the greatest possible error will occur at the half way point.
The 1 in 60 rule can be used here.
Expressed as a formula it is:
distance off track = track error angle
distance gone 60
or,
distance gone = distance off track x 60
track error angle
The maximum distance off track is 5nm, track error angle is 5.5º so
distance to half way = 5 x 60 ÷ 5.5 = 54.5nm
distance between the beacons is twice that, 109 nm.
What is the approximate angular coverage of reliable navigation information for a 3° ILS glide path out to a minimum distance of 10 NM?
1.35° above the horizontal to 5.25° above the horizontal and 8° each side of the localiser centreline
……………….
The glide slope coverage of an ILS goes from 0.45 to 1.75 times the glidepath angle
so for our 3° glideslope this is 0.45 x 3° = 1.35°
and 1.75 x 3° = 5.25°
Which of the following statements about the range of VHF waves is correct?
The range depends on the elevation of the antenna located on the ground and on the altitude of the aircraft.
On what carrier frequency does the inner marker transmit?
75 MHz.
……………
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 middle marker transmits on:
75 MHz
……………..
The system (transmission) frequency for all marker beacons is 75 MHz.
The principle of operation of an ILS is:
the difference in depth of modulation.
In order to plot a bearing from a VOR station, a pilot needs to know the magnetic variation:
at the VOR
Night effect is a phenomenon that affects NDB signals at night, caused by Sky Waves being reflected back from the ionosphere. This happens because:
At night the D layer in the ionosphere disappears and the signals reach the E and F layers which reflect them back.
The maximum theoretical range at which an aircraft at FL80 can obtain bearings from a ground VDF facility sited 325 ft above MSL ?
132 NM
The reading of the RMI bearing is 300° at the tip of the needle. The magnetic variation at the DR position is 24°W, the magnetic variation at the NDB is 22°W and the deviation is -2°. The compass heading is 020°. The true bearing is:
274°
Outer marker beacons of an ILS transmit at:
75 MHz.
An ILS receiver:
measures the difference in depth of modulation of the two transmitted signals.
The Instrument Landing System (ILS) uses the following wavelengths:
metric.
……………
The ILS frequency range is 108.10 MHz to 111.95 MHz. Using a medium frequency of 110 MHz, the wavelength is:
Wavelength (λ) = speed of light (c) ÷ frequency (f) = 300 000 000 m/s ÷ 110 000 000 Hz = 2.73 m
This is in the metric band (1 m – 9.99 m).
The ILS receiver of an aircraft on approach and flying on the glidepath will receive:
the modulation from both lobes at equal depth.
Regarding monitoring system of the VOR - which statement is correct?
failure of the VOR station to stay within required limits can cause removal of identification and the navigation components from the carrier wave to cease.
The two signals transmitted by a conventional VOR ground station are 90° out of phase on magnetic:
east
…………
With the conventional VOR the phase difference between the variable phase and the reference phase represent the radial the aircraft is on, i.e. if the phase difference is 90º, the aircraft is on radial 090 or East of the station.
The ILS marker with the lower aural frequency is the:
outer marker.
………………..
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
An aircraft is flying on the 170 radial with a MH of 315º. On the CDI the CRS is set to 180.
Which CDI shows the correct indications?
Figure D
On a DME, display counters rotating throughout their range indicates:
the airborne receiver is conducting a range search
The type of modulation used for the ILS frequency carrier is:
amplitude modulation.
……………………
The ILS use amplitude modulation (AM) to transmit the 90 Hz and 150 Hz signals of the lobes for both localiser and glideslope.
Regarding conventional VORs:
The variable signal antenna rotates at 30 times per second whilst the reference signal is produced from a fixed antenna.
Which answer states the typical distances along the centerline of the runway of the various ILS components?
Localizer transmitter: 300 metres behind end of runway, Glide path transmitter: 300 metres behind threshold, Middle Marker: 1000 metres from threshold, Outer Marker: 4 NM from threshold.
An aircraft is flying on a MH of 010°.
The magnetic variation at the VOR is 10°W and at the aircraft 12°W.
Which VOR-RMI corresponds to the indications on the HSI shown on the Annex?
Figure C
An aircraft DME receiver does not lock on to its own transmissions reflected from the ground because:
they are not on the receiver frequency
Classify the marker from lower aural frequency to higher aural frequency : 1. Inner marker (if available) 2. Middle marker 3. Outer marker
3 - 2 -1
A VOR and an NDB are located in the same position. Both the VOR- and the ADF-readings are displayed on the RMI. The aircraft is tracking away from the beacons along the 090 radial. The magnetic variation is changing rapidly. Which of the following is correct?
The direction of the ADF pointer will change, the direction of the VOR pointer will not change.
An aircraft’s position is on a 36° (T) bearing from a VOR station and it is maintaining a heading of 330° (T). The magnetic variation at the VOR station and at the aircraft is 8°E. What OBS setting would make the CDI needle centre with a “TO” indication showing?
208°
…………
When situated on the R-028° radial FROM the VOR the OBS should be selected to 208° to obtain a centred needle with a TO indication.
Which of the following frequencies is within the DME frequency band?
1000 MHz
………….
The DME frequency range is 960 MHz to 1215 MHz.
A failed RMI rose is locked on 090° and the ADF pointer indicates 225°. The relative bearing to the station is :
135°.
……………….
The a/c is not heading 090! the compass rose is stuck on 090. the relative bearing of the beacon is 135 degrees from the actual aircraft heading (which we are not given) The beacon position is referenced clockwise from the nose of the a/c.
The original compass rose card for the ADF was fixed ie a piece of paper stuck behind a needle with north at the top. Relative bearings are always taken clockwise around the card. In this case there is 135 degrees between the nose of the a/c (indicating 090) and the pointer indicating 225 degrees (to the NDB) on the card. The maths is easy 225-090 = 135 degrees.
An aeroplane flies over position A which is due North of a VOR station sited at position B. The magnetic variation at A is 18°W, and at B is 10°W. What radial from B is the aircraft on?
010°
……….
Since the aircraft is North of the VOR, the true bearing of the aircraft from the VOR is 360º.
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 000ºT ± 10W = 010ºM. Therefore, the aircraft is on radial 010.
Which of the following statements concerning the variable, or directional, signal of a conventional VOR is correct?
The rotation of the variable signal at a rate of 30 times per second gives it the characteristics of a 30 Hz amplitude modulation
The localiser transmits in:
the VHF band.
……………
The localiser transmit in the VHF band (108.10 MHz – 111.95 MHz).
The glideslope transmit in the UHF band (329.15 MHz – 335 MHz).
Inner marker beacons of an ILS transmit at:
75 MHz.
…………….
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.
Assuming a five dot display on either side of the CDI on the ILS localiser cockpit display, what does each of the dots represent approximately ?:
0.5 degrees
……………
Full scale defection for the localiser display indicates 2.5º displacement from the localiser centreline.
If there is 5 dots either side of centre on the CDI, each dot represent 2.5º ÷ 5 = 0.5º per dot.
Using the attached image: Which of the CDI displays shown at the annex indicate that the aircraft is at the maximum recommended deviation both below the glidepath and to the right of the centreline?
C
The VDF class C bearing is accurate to within:
+10
According to the ILS coverage area as defined by ICAO Annex 10, in which of the following situations will the pilot be guaranteed a reliable signal from the localiser?
20 NM from touchdown inbound and 8° displaced from the localiser centreline.
In ISA conditions, approximately what is the maximum theoretical range at which an aircraft at FL210 may expect to receive signals from a VOR facility sited 340 feet above mean sea level ?
204 NM
………………
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 (v340 ft + v21 000 ft) = 200.9 nm
An aircraft is carrying out an ILS approach. It is receiving a localiser signal with 150Hz and 90 Hz modulations. Which of the following statements is correct?
The 150 Hz modulation predominates to the right of the centre line
An aircraft is flying on a heading of 270°(M). The VOR OBS is also set to 270° with the full left deflection and FROM flag displayed. In which sector is the aircraft from the VOR ground station?
NW
DME channels utilise frequencies of approximately:
1000 MHz
The Automatic Direction Finder uses the following wavelengths:
hectometric or kilometric.
Reflection on mountain surfaces (mountain effect) can concern:
VOR and NDB.
A Course Deviation Indicator (CDI) shows full deflection to the left when within range of a serviceable VOR. What angular deviation are you from the selected radial?
10° or more
The BFO selector on an ADF receiver is used to:
hear the IDENT of some NDB stations radiating a continuous wave signal
What airborne equipment, if any, is required to be fitted in order that a VDF let-down may be flown?
VHF radio
An aircraft is flying a heading of 245° towards a VOR at FL300. The HSI displays a “selected course” of 255º with a TO-indication. The variation at the VOR is 15ºE. Variation at the aircraft position is 16°E and the deviation is +1°.
When the pilot keeps the CDI on the left inner dot on a display with two dots on either side:
the VOR will be approached along radial 070.
The three different markers can be used in the ILS to determine the distance to the ILS touchdown point of the runway as follows:
The middle marker indicates the position for the decision for a missed approach during a CAT I approach due too bad visibility.
What is measured in depth between the 90 Hz modulation and the 150 Hz modulation:
The difference in depth between the 90 Hz modulation and the 150 Hz modulation.
ILS transmitters use the:
UHF and VHF bands.
……………
The ILS use transmissions in the VHF band for the localiser signal (108.10 MHz – 111.95 MHz) and in the UHF band for the glideslope signal (329.15 MHz – 335 MHz).
An aircraft is flying on the 050 radial with a MH of 250º. On the HSI the CRS is set to 060. Which HSI shows the correct indications?
Figure B
Which statement is correct with respect to the different types of VOR?
A TVOR has a limited range.
Given :
Aircraft position 34°15’N 098°E, magnetic variation 28°W, FL 280.
PTC VOR/DME position 36°12’N 098°E, magnetic variation 13°E.
In order to read the most accurate ground speed given by the DME receiver from his present position, the pilot must fly on which PTC Radial?
167°
…………
The groundspeed will be most correct when the aircraft is flying directly towards or away from the DME.
The aircraft and the VOR are on the same longitude (E09800), i.e. the aircraft is either due North or due South of the VOR. As the VOR is at N3612 and the aircraft at N3415, the aircraft is South of the VOR making the direction of the aircraft from the VOR 180ºT.
As a VOR radial is magnetic referenced to the variation at the VOR, the aircraft is on radial: 180ºT – 13ºE = 167º.
Which of the following alternatives is correct regarding audio- and visual signals in cockpit when passing overhead a middle marker?
Audio: 1300 Hz, alternating dots and dashes. Visual: Amber light flashes.
The rate of descent required to maintain a 3.25° glide slope at a groundspeed of 140 kt is approximately:
760 FT/MIN
………………
For glideslopes with an angle of other than 3º use the following calculation:
Rate of descent (ft/min) = (groundspeed ÷ 60) x glideslope angle x 100
Rate of descent = (groundspeed ÷ 60) x glideslope angle x 100 = (140 kts ÷ 60) x 3.25 x 100 = 758 ft/min
One of the possible disturbances of the ILS signal is “scalloping.” Which statement is correct?
Scalloping causes rapid indicator changes from side to side of the intended approach path which can not be followed by the aircraft.
…………………….
Scalloping is an error that is associated with both localiser and glideslope and are small variations (or wave like bends) occurring to the signal due to external influences. This scalloping will cause smaller deflection of the indicator that may be too rapid for the aircraft to follow.
Your QUJ is 335° by VDF. The variation of a VOR at the same location is 12°W. What is the phase difference between the reference and variable phase signals being received at the aircraft from that VOR?
167°
What according to ICAO Annex 10 is the range of a locator?
10 - 25 NM
……………….
A locator beacon is an NDB whose primary function is to act as an approach aid, therefore, a locator will often have a short range defined as 10 nm – 25 nm.
You are flying along an airway which is 10 NM wide (5 NM either side of the centreline). The distance to the VOR/DME you are using is 100 NM. If you are on the airway boundary, how many dots deviation will the VOR needle show if one dot represents 2 degrees?
1.5
………..
The maximum safe ‘Fly up’ indication on the glidepath needle (assuming a 5-dot indicator) is:
2.5 dots
………………..
The aircraft’s position relative to the runway extended centreline (C/L) is shown by the Course Deviation Indicator (CDI) vertical Localiser (LOC) needle, which indicates aircraft position left or right of C/L.
If the needle is displaced to the left the aircraft is right of C/L.
If the needle is displaced to the right the aircraft is left of C/L.
The aircraft’s position relative to the glide path (GP) is shown by the Course Deviation Indicator (CDI) horizontal Glide Path (GP) needle, which indicates aircraft position above or below GP.
If the needle is displaced upwards the aircraft is below GP.
If the needle is displaced downwards the aircraft is above GP.
An ADF provides the aircraft with bearing information with respect to a ground station. To do this, the ground station emits a signal pattern which is:
omnidirectional
………………………
The radiation pattern from an NDB is omnidirectional, i.e. of equal signal strength in all directions from the antenna. It can be said to operate like any simple radio transmitter.
By selecting one VHF frequency, in the range of 108 to 112 MHz, on the NAV receiver
rho-theta information from a terminal VOR/DME can be obtained.
………………….
For the purpose of the exams:
Terminal VORs are allocated frequencies in the range 108.00 - 112.00 MHz, which is shared with ILS. En-Route VORs are allocated frequencies in the range 112.00 - 117.95 MHz.
Instrument Landing Systems (ILS) Glide Paths provide azimuth coverage (i)…. ° each side of the localiser centre-line to a distance of (ii)…. NM minimum from the threshold.
(i) 8° (ii) 10
…………………
The glideslope coverage area is within 0.45 and 1.75 x the glideslope angle and 8º either side of the localiser centreline to a distance of 10 nm.
An aircraft is flying on the 245 radial with a MH of 250º. On the CDI the CRS is set to 060.
Which CDI shows the correct indications?
Figure D
At a distance of 25 NM from the threshold a localiser must provide a minimum horizontal coverage of:
10° each side of the localiser centre.
The standard minima for a CAT I ILS approach are:
DH 200 ft; RVR 550 m.
Using the attached image:
What is the aircraft’s position, as determined from the annex shown?
Left of selected course, DME distance decreasing
In the DME “tracking mode”:
interrogator transmits a relatively low number of pulse pairs per second.
An aircraft has a Magnetic Heading of 290º and is on VOR radial 280. Which value has to be selected on the OBS to get a TO indication and the CDI centred?
100°
An aircraft is flying on a MH of 010°.
The magnetic variation at the VOR is 10°W and at the aircraft 12°W.
Which VOR-RMI corresponds to the indications on the CDI shown on the Annex?
Figure A
DVOR is less sensitive to site errors than CVOR. This is because:
the DVOR antenna is comparatively larger than the CVOR antenna.
The ILS marker identified visually by an blue flashing light is the:
outer marker.
Concerning the glidepath principle of operation in an ILS system, the needle of the 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.
The basic principle of operation of the ILS is the difference in depth of modulation (DDM) between the two lobes:
- if the aircraft strays right, the higher tone lobe will be received at a higher intensity than the lower tone lobe.
- a DDM of zero indicates the exact runway centreline.
- the depth of modulation increases away from the centerline.
- a DDM of zero indicates a balance between modulations.
The combination that regroups all the corrects statements is:
1, 2, 3 and 4.
Which statement is true if you compare raw data with computed data?
Conventional radio navigation is based on raw data like information from navigation aids and measured air data.
With reference to a VOR, the cone of confusion is:
the area directly overhead a VOR
MLS is primarily being installed at airports where:
ILS encounters difficulties because of surrounding buildings and/or the terrain or interference from local music stations.
An aircraft carrying out an ILS approach is receiving more 90 Hz than 150 Hz modulation notes from both the localiser and glidepath transmitters. The ILS indication will show:
Fly right and fly down
An aircraft is flying on a MH of 010°.
The magnetic variation at the VOR is 10°W and at the aircraft 12°W.
Which VOR-RMI corresponds to the indications on the HSI shown on the Annex?
Figure B
……………
The course selected on the course selector is 060º 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 10º to the left of the selected course (060º), i.e. 060º + 10º = 070º.
The aircraft is on radial 070º + 180º = 250º.
The RMI will indicate the aircraft heading (010º) and the tail of the needle will point at the present radial, i.e. 250º, and the head of the needle will point towards the station along that radial, i.e. a course of 250º – 180º = 070º.
An aircraft tracking to intercept the Instrument Landing System (ILS) localiser inbound on the approach side, outside the published ILS coverage angle:
may receive false course indications
The scanning beam of the MLS system is called:
Time reference scanning beam (TRSB).
A VOR and a NDB are co-located. You cross the VOR radial of 240° on a heading of 360°(M). In the vicinity of the station you should read an ADF bearing of:
060
If an aircraft flies along a VOR radial it will follow a:
great circle track
…………………..
As the question does not specify short or long distances and as we know magnetic track changes over distance (even short ones) therefore the answer has to be a Great Circle Track.
VDF measures the bearing of the aircraft with:
reference to true or magnetic north at the station.
The ILS marker with the higher aural frequency is the:
inner marker.
An aircraft at FL300, with a groundspeed of 300 kt, is about pass overhead a DME station at MSL. The DME receiver is capable of determining ground-speed. One minute before the overhead, DME speed and distance indications are respectively:
less than 300 kt and 7 NM.
………………….
What approximate rate of descent is required in order to maintain a 3° glide path at a groundspeed of 120 kt?
600 FT/MIN
…………….
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 = 120 kts x 5 = 600 ft/nm
An aircraft carrying out an ILS approach is receiving more 150 Hz than 90 Hz modulation from both the localiser and glide path transmitters. The ILS indication will show:
fly left and up
…………….
Ground direction finding at aerodromes utilises which frequencies?
VHF at civil aerodromes and UHF at military aerodromes
The amplitude modulation and the colour of an outer marker (OM) light is:
400 Hz, blue
Which statement is correct with respect to the range of an NDB?
With propagation over sea the range will be greater than the range with propagation over land.
In the VOR receiver the radial is determined by measurement of the
phase difference between the variable signal and the reference signal.
A DME station is located 1000 feet above MSL. An aircraft flying at FL 370 in ISA conditions which is 15 NM away from the DME station, will have a DME reading of:
16 NM
An aircraft is required to approach a VOR station via the 244° radial. In order to obtain correct sense indications the deviation indicator should be set to:
064° with the TO flag showing
What is the “Q” code for a magnetic bearing from a VDF station?
“Request QDR”.
……………….
The Q codes used in relation to direction finding are:
- QDM: Magnetic bearing to the station.
- QDR: Magnetic bearing from the station.
- QUJ: True bearing to the station.
- QTE: True bearing from the station.
The BFO selector switch on the ADF control panel must be in the ‘on’ position to enable the pilot to:
hear the IDENT of NDBs using NON A1A transmissions
…………………..
NON A1A are the older type where you need to select BFO to ON to hear the IDENT.
NON A2A are the newer type where the BFO does not need to be selected on.
Errors caused by the effect of coastal refraction on bearings at lower altitudes are maximum when the NDB is:
inland and the bearing crosses the coast at an acute angle
………………..
The effect of coastal refraction will increase with increasing distance of the NDB from the coast. If the aircraft is on a bearing that cross the coast at a right angle, the coastal refraction will be non-existent regardless of the distance the NDB is inland from the coast. An acute angle between the bearing and the coast will give the greatest effect of coastal refraction.
Which one of the following correctly lists the major ground based components of a Microwave Landing System (MLS)?
Separate azimuth and elevation transmitters, DME facility
………………….
The MLS utilise separate azimuth (horizontal guidance), elevation (vertical guidance) and DME-P (range) facilities.
To provide a pilot with the position of the aircraft in the absence of radar, ATC must have at its disposal at least
two VDF’s at different locations, able to take bearings simultaneously on the transmitted frequency.
Regarding the DME system, which one of the following statements is true?
The transponder reply carrier frequency differs by 63 MHz from that of the interrogation signal.
What is measured in order to establish aircraft position in relation to the localizer beam on an ILS?
The difference in depth between the 90Hz modulation and the 150Hz modulation.
The UHF band is the assigned frequency band of the:
ILS glide path transmitter.
………………..
The glideslope transmit in the UHF band (329.15 MHz – 335 MHz).
The localiser transmit in the VHF band (108.10 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).
The ILS marker identified audibly by a series of alternate dots and dashes is the:
middle marker.
In an ILS system, concerning the glidepath principle of operation, the difference in depth of modulation (DDM):
- decrease with angular displacement below the glidepath.
- increase with angular displacement above the glidepath.
- decrease with angular displacement above the glidepath.
- increase with angular displacement below the glidepath.
The combination regrouping all the correct statements is:
2 and 4.
An aircraft is on radial 120 with a magnetic heading of 300°, the track selector (OBS) reads: 330. The indications on the Course Deviation Indicator (CDI) are ‘fly’:
left with ‘TO’ showing
The audio frequency modulation of the middle marker shall be keyed as follows:
a continuous series of alternate dots and dashes, the dashes keyed at the rate of 2 dashes per second, and the dots at the rate of 6 dots per second.
Which one of the following is an advantage of a Microwave Landing System (MLS) compared with an Instrument Landing System (ILS)?
It is insensitive to geographical site and can be installed at sites where it is not possible to use an ILS
On final on an ILS approach, you are flying overhead the outer marker. You can expect to be at:
4 NM from the threshold.
The DME (Distance Measuring Equipment) operates within the following frequencies:
962 to 1213 MHz
Which of the following is correct regarding false beams on a glide path?
False beams will only be found above the correct glide path.
The ILS receiver of an aircraft on approach and flying on the right of the exact runway centreline will receive:
more of the 150 Hz localiser signal than the 90 Hz localiser signal.
On an ILS approach, when flying overhead the middle marker the color of the flashing light will be:
amber.
Which of the following is an ILS localiser frequency?
109.15 MHz
……………
The localiser frequency range (as well as the ILS system frequency) is 108.10 MHz to 111.95 MHz with the first decimal place being odd numbers only, i.e. 108.10, 108.15, 108.30, 108.35, 108.50 etc.
Which of the following is the ICAO allocated frequency band for ADF receivers?
190 - 1750 kHz
A VOR and DME are co-located. You want to identify the DME by listening to the Mores code identifier. Having heard the same callsign 4 times in 30 seconds the:
DME Morse ident is the one with the higher pitch that was broadcast only once
If you are flying an ILS back-beam approach, you are flying a:
Non-precision approach on the reciprocal runway of the precision approach runway.
An NDB is:
Non-directional radio beacon.
A MLS without DME-P provides:
An ILS-like approach
For Long Range NDB’s the most common type is:
LF N0N/A2A
The selection of code 2000 on an aircraft SSR transponder indicates:
entry into airspace from an area where SSR operation has not been required
TVOR is a
VOR with a limited range used in the terminal area.
………………..
The TVOR, or terminal VOR, is a VOR with limited range used within a terminal area as part of the approach and departure structure at an airport.
The ILS middle marker modulation frequency is:
1300 Hz.
Quadrantal errors associated with aircraft Automatic Direction Finding (ADF) equipment are caused by:
signal bending by the aircraft metallic surfaces
On an ILS approach, when flying overhead the outer marker the colour of the flashing light will be:
blue.
Given: Course Deviation Indicator (CDI) for a VOR is selected to 090°. From/To indicator indicates “TO”. CDI needle is deflected halfway to the right. On what radial is the aircraft?
275
A DME is located at MSL. An aircraft passing vertically above the station at flight level FL 360 will obtain a DME range of approximately:
6 NM
………
The DME will indicate the line of sight distance to the station, i.e. when the aircraft is directly overhead, the indicated distance will be equal to the aircraft altitude (height).
36 000 ft ÷ 6080 ft/nm = 5.9 nm
The audio frequency modulation of the outer marker shall be keyed as follows:
2 dashes per second continuously.
Mountain effect, occurring for instance with NDBs, is caused by what physical phenomenon?
reflection.
A locator:
1 - is a low powered beacon.
2 - is a high powered beacon.
3 - has a range of 10 – 25 NM.
4 - has a range of 10 -200 NM.
1 and 3
The MIDDLE MARKER of an Instrument Landing System (ILS) facility is identified audibly and visually by a series of:
alternate dots and dashes and an amber light flashing
An NDB has a range of 50 NM with a power output of 80 W. The power required to increase the range to 75 NM is:
180 W.
MLS installations notified for operation, unless otherwise stated, provide azimuth coverage of:
+/- 40° about the nominal courseline out to a range of 20 NM
An NDB transmits a signal pattern in the horizontal plane which is:
omnidirectional
An aircraft is on the 065 radial with a heading of 090ºM.
The Course Reference Selector (CRS) is set on 240.
Which HSI shows the correct indications?
B
The sensitive area of an ILS is an area vehicles or taxiing aircraft may not enter when:
Category II/III operations are in progress.
So as to avoid inaccuracies that may be caused by coastal refraction, the pilot should take an ADF bearing when:
the aircraft is passing the NDB on a line perpendicular with the coastline.
You are on an ILS approach and the glide slope indicator shows a deviation of more than half scale (indicating that the aircraft is below the glide path). You should:
commence a go-around because obstacle clearance is no longer assured.
The VHF Omni-range (VOR) uses the following wavelengths:
metric.
…………….
The VOR frequency range is 108.00 MHz to 117.95 MHz. Using a medium frequency of 110 MHz, the wavelength is:
Wavelength (?) = speed of light (c) ÷ frequency (f) = 300 000 000 m/s ÷ 110 000 000 Hz = 2.72 m
This is in the metric band (1 m – 9.99 m).
A VOT is:
a test VOR
Which one of the following disturbances is most likely to cause the greatest inaccuracy in ADF bearings?
Local thunderstorm activity
If an NDB with a transmitter power of 25 KW which has a range of 50 NM is adjusted to give a power output of 100 KW, the new range of the NDB will be approximately:
100 NM
……………..
Remember an NDB station’s range is directly proportional to the square root of it’s transmitter range.
NEW Power ÷ OLD Power = (New Range ÷ Old Range)²
100 ÷ 25 = (New Range ÷ 50)²
square root of 4 = New Range ÷ 50
2 X 50 = 100 NM
New Range = 100 NM
When the warning flag on a VOR indicator appears, it may indicate:
All answers given are correct.
If VOR bearing information is used beyond the published protection range, errors could be caused by:
interference from other transmitters
The principle used in VOR bearing measurement is:
phase comparison
The ILS marker with an aural frequency of 1300 Hz is the:
middle marker.
The ADF indication in the cockpit is a
relative bearing on a fixed card indicator
Outer marker transmits on 75 MHz and is modulated by has an aural frequency of:
400 Hz
According to ICAO Annex 10, in which frequency band(s) does a locator normally transmit?
LF/MF
Which of the following factors could cause an error of an ADF bearing of an NDB?
Night effect
Concerning ADF and NDB:
NDB is a ground equipment, and ADF is an airborne equipment.
The OBS is set on 048°, TO appears in the window. The needle is close to full right deflection. The VOR radial is approximately:
238°
There are two NDBs, one 20 NM inland, and the other 50 NM inland from the coast. Assuming that the error caused by coastal refraction is the same for both propagations, the extent of the error in a position line plotted by an aircraft that is over water will be:
smaller from the beacon that is 20 NM inland
How can a DME-interrogator distinguish between its own reply pulse-pairs and the reply pulse-pairs of other aircraft in the area, using the same DME-station?
The Pulse Repetition Frequency of the pulse-pairs transmitted by the interrogator varies, for each interrogator, in a unique rhythm.
Concerning the localiser principle of operation in an ILS system, the difference in depth of modulation (DDM) :
- decreases with respect to the angular displacement from the centerline.
- increases with right displacement from the centerline.
- decreases with left displacement from the centerline.
- increases linearly with displacement from the centreline.
The combination regrouping all the correct statements is:
2 and 4.
The accuracy of a DME:
Decreases with range.
The ILS marker identified audibly by a series of two dashes per second is the:
outer marker.
All ILS marker beacons transmit at:
75 MHz.
The ILS receiver of an aircraft flying down the exact runway centreline will receive:
90 Hz and 150 Hz lobes at equal depth.
Which aircraft will be denied first, if the number of pulse pairs received by a DME transponder exceeds the maximum number possible?
The aircraft from which the weakest pulse pairs are received.
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 CDI shown on the Annex?
Figure D
If a failed RMI rose is stuck on 090° and the ADF pointer indicates 225°, the relative bearing to the station will be:
135°.
Which statement about the interrogation by the DME-interrogator is correct?
The interrogation does not start before pulse-pairs of the tuned DME-station are received.
At reference.
At which of the four positions is the error of the signal, due to coastal refraction, of VNC NDB lowest?
Position C
In order to obtain an ADF bearing on a system using sense and loop aerials, the:
signal must be received by both the sense and loop aerials
With regard to the range of NDB’s and the accuracy of the bearings they provide can be stated that in general at night
the range increases and the accuracy decreases.
On which bearing do errors caused by the shoreline/coastal effect reach their maximum?
Bearings 0°-30° degrees to the coastline
The basic principle of operation of the ILS is the difference in depth of modulation (DDM) between the two lobes:
- A DDM of zero indicates a balance between modulations;
- A DDM of zero indicates the exact runway centreline;
- The depth of modulation increases away from the centerline;
- If the aircraft strays right, the higher tone lobe will be received at a higher intensity than the lower tone lobe;
The combination that regroups all the corrects statements is:
1,2,3,4
Referring to the Pamplona (PPN) radio navigation aid shown at the Annex, if the aircraft is within range and the PPN VHF frequency 112.3 MHz has been suitably tuned into the relevant VHF NAV/DME equipment:
Slant range can be provided because the VHF frequency has a paired DME UHF frequency
The principle of operation of an ILS localiser transmitter is based on two overlapping lobes that are transmitted on (i)………. frequencies and carry different (ii)……….
(i) the same (ii) modulation frequencies
DVOR is more accurate than CVOR because of the:
fact that the variable phase is frequency modulated instead of amplitude modulated (as with CVOR).
The captain of an aircraft flying at FL100 wishes to obtain weather information at the destination airfield from the airfield’s VOR. Assuming ISA conditions, what is the approximate maximum theoretical range at which it can be expected to obtain this information?
123 NM
……………………
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 + v10 000 ft) = 123 nm
VDF is the abbreviation for:
VHF Direction Finder.
An aircraft is on the 120° radial from a VOR station. Course 340° is selected on the HSI (Horizontal Situation Indicator). If the magnetic heading is 070°, the deviation bar relative to the aeroplane model, will be:
behind.
The main factor that limits the range of an NDB is:
the transmitted power.
The frequency range of a VOR receiver is:
108 to 117.95 MHz
An aircraft is flying directly overhead a DME station at FL410. The indicated range will be approximately:
6.8 NM
………..
1NM = 6000ft
FL410 = 41000ft
41000/6000 = 6.8NM
Performing an ILS approach, you will fly overhead the markers in an specific order. This order is:
OM, MM, IM (if available).
An aircraft is on the 075° radial from an NDB with a heading of 295°M. The relative bearing on ADF is:
320°
……………
If the aircraft is on radial or QDR 075º, it is to the east northeast of the NDB and the bearing to the NDB (QDM) will be 075º + 180º = 255º.
The aircraft is on a heading of 295º, i.e. heading a bit to the right of the inbound course to the NDB. Since the needle of the RBI will point at the NDB, it will point a bit to the left of the top of the instrument (360º), making 320º the only sensible alternative. This can also be calculated:
Relative bearing = magnetic bearing to – magnetic heading = 255º – 295º = -40º + 360º = 320º
The addition of DME-P to MLS is necessary to:
obtain three dimensional positions.
………………..
In order to obtain a 3 dimensional fix it is necessary to have guidance both horizontally (azimuth), vertically (elevation) and range (DME-P).
What is the maximum distance between VOR and DME/TACAN ground installations if they are to have the same Morse code identifier?
600 m
……………
The maximum distance between VOR and DME/TACAN ground installations, if they are to have the same Morse code identifier, is 600m.
An aircraft is required to approach a VOR via the 104° radial. Which of the following settings should be made on the VOR/ILS deviation indicator?
284° with the TO flag showing
A VOR is situated at the far end of a runway on which an aircraft is making an ILS approach. Nav 1 is switched to the localiser frequency and Nav 2 to the VOR frequency. At the moment that the needle of # 1 indicator reaches the outer dot the deflection of the needle of # 2 indicator will be at:
approximately a quarter of the scale.
With regard to the monitoring of a VOR. The monitor will remove the identification or switch off the VOR transmitter if there is a change of measured bearing greater than:
1°
Given: Aircraft heading 160°(M), Aircraft is on radial 240° from a VOR, Selected course on HSI is 250°. The HSI indications are deviation bar:
behind the aeroplane symbol with the FROM flag showing
An RMI slaved to a remote indicating compass has gone unserviceable and is locked on to a reading of 090°. The tail of the VOR pointer shows 135°. The available information from the VOR is:
Radial 135°, relative bearing unknown
Which of the following is correct regarding the range of an NDB?
Aircraft height is not limiting for the reception of signals from the NDB.
ICAO specifications are that range errors indicated by Distance Measuring Equipment (DME) should not exceed:
+ or - 0.25 NM plus 1.25% of the distance measured
A locator beacon differs from an NDB with respect to: 1. operational use 2. transmission power 3. presentation in the cockpit 4. frequency band. From the above stated differences the following numbers are correct:
1 and 2
Concerning the localiser principle of operation in an ILS system, the difference in depth of modulation (DDM):
increases linearly with respect to the angular displacement from the centerline.
In which frequency band do VOR transmitters operate?
VHF
…………..
VOR operate in the VHF frequency band with frequency range 108.00 MHz to 117.975 MHz.
A Category 1 Instrument Landing System (ILS) ground installation provides accurate guidance from coverage limit down to:
200 feet above the runway threshold
If a DME transponder becomes saturated it will:
Give preference to the aircraft with the strongest transmissions
Which one of the following methods is used by a Microwave Landing System (MLS) to indicate distance from the runway threshold?
A precision facility DME
The ident of a DME in case of collocation with a VOR is as follows:
In 40 seconds the DME ident will sound once.
One of uses of the VDF service is providing aircraft with:
homing.
According to ICAO Annex 10 a locator has a range of:
10 to 25 NM
The identification of a DME in combination with a co-located VOR is as follows:
In a period of 40 seconds the DME ident will be heard once on an audio frequency of 1350 Hz.
Given:
Aircraft position 52°09’S 024°E, magnetic variation 14°W, FL 310.
BIT VOR/DME position 54°42’S 024°E, magnetic variation 14°E.
In order to read the most accurate ground speed given by the DME receiver from his present position, the pilot must follow which BIT radial?
346°
The audio modulation of the middle marker is keyed to give
alternating dots and dashes at a rate of 2 dashes per second and 6 dots per second
What is the minimum level (ISA conditions) that an aircraft, at a range of 113 NM, must fly in order to contact the tower on R/T for a VDF bearing from an airport sited 169 FT above MSL?
FL80
…………..
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)
Rearranged to find the height of the aircraft gives the following calculation:
Height of the aircraft = ((VHF range ÷ 1.23) - √height of the station)² = ((113 nm ÷ 1.23) - √169)² = 6220 ft
Therefore, the minimum pressure altitude at which the aircraft can fly would be FL 63 (6300 ft), however, this is not on offer.
In that respect, the lowest pressure altitude on offer is FL 80.
NOTE: It is understood that the ‘correct’ answer in the ECQB may be FL 60, owing to the question author incorrectly using a multiplication factor of 1.25 (Learning Objectives state 1.23)
If you see this question in your examination, you are advised to notify your ATO.
MLS consists of:
An Azimuth transmitter and an Elevation transmitter operating on a shared frequency and a DME.
……………..
The Microwave Landing System comprises three separate antennas:
Azimuth antenna, for lateral navigation
Elevation antenna, for vertical navigation
DME/P (Precision DME) for distance measurement
An aircraft passes overhead a DME station at 12000 feet above the station. At that time, the DME reading will be:
approximately 2 NM.
……………….
The DME will indicate the line of sight distance to the station, i.e. including a combination of ground distance and aircraft height above the station.
Directly overhead the station the DME will indicate the aircraft height in nm, 12 000 ft ÷ 6080 ft/nm = 2 nm
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 CDI 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 OBI.
The OBS 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 selection of the DME frequency for a ILS/DME installation is as follows:
The DME frequency is paired with the localizer frequency so only the localiser frequency is set.
The VHF direction finder uses the following wavelengths:
metric.
Distance Measuring Equipment (DME) operates in the:
UHF band and uses two frequencies
……………..
The DME frequency range is 960 MHz to 1215 MHz which is within the UHF frequency band (300 MHZ – 3000 MHz) and use two frequencies separated by 63 MHz for interrogation and reply.
Which statement is correct for homing towards an NDB in an area with constant wind and constant magnetic variation?
The Relative Bearing of the NDB should be kept 000°.
The minimum airborne equipment required for operation of a VHF direction finder is a:
VHF transmitter-receiver operating in the 118 MHz to 136 MHz range.
The reason for using different frequencies for transmitting and receiving in the DME system is:
To prevent self-triggering of the receiving equipment by the transmitter.
Which of the following is an advantage of Ground/DF (VDF) let-down?
It only requires a VHF radio to be fitted to the aircraft
Which of the following affects VDF range?
The height of the transmitter and of the receiver.
False beams on the ILS glidepath are:
only found above the correct glideslope
The aircraft DME receiver cannot lock on to interrogation signals reflected from the ground because:
aircraft transmitter and DME ground station are transmitting on different frequencies
The antenna polar diagram of a Conventional VOR (CVOR):
Rotates at 30 revolutions per second
An RMI indicates aircraft heading and bearing. To convert the RMI bearings of NDBs and VORs to true bearings the correct combination for the application of magnetic variation is:
NDB: aircraft position VOR: beacon position
An NDB is on a relative bearing of 316° from an aircraft. Given: Compass heading 270° At aircraft deviation 2°W, Variation 30°E At station Variation 28°E, Calculate the true bearing of the NDB from the aircraft
254°
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 largest errors?
C & D and the signal bends towards the coast
The operating principle of a DME is the measurement of the:
time between the transmission and reception of radio pulses
If a DME beacon becomes saturated by interrogations it:
adjusts the gain to reply to the 100 strongest signals
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.
Of what use, if any, is a military TACAN station to civil aviation ?
It can provide DME distance
If the reference phase differs 30° with the variable phase the radial from the VOR station will be :
030°
…………….
The radial from a VOR is determined by the phase difference between the reference signal and the variable signal.
If there is 30º difference between them the receiver will be on radial 030º regardless of whether the radial is based on a conventional VOR or a doppler VOR.
The ILS inner marker (if available) modulation frequency is:
3000 Hz.
In order to measure the radial from a VOR, the aircraft VOR receiver
measures the phase difference between the reference phase and the variable phase of the signal.
What is the audio frequency of the inner marker?
3000 Hz
DME operates on the principle of …..(1)…..radar system which provides….(2)…..distances between the aircraft and the ground…..(3)……..
(1) secondary (2) slant (3) transponder
The localiser transmitters operate in a frequency band between:
108 MHz and 111.975 MHz.
What is the “Q” code for a true bearing to a VDF station
QUJ
…………
The ‘Q Code’ for a true bearing to a VDF station is a ‘QUJ’
Background Information
The following ‘Q Code’ descriptors are:
- QDM - Magnetic Bearing TO
- QDR - Magnetic Bearing FROM
- QUJ - True Bearing TO
- QTE - True Bearing FROM
During a flight at FL 210, 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
…………………..
The maximum theoretical range of a DME 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 (SQRT0 ft +SQRT21 000 ft) = 178.2 nm
With the approximate distance between the aircraft and the station being 220 nm, this is beyond line of sight and the maximum range at the present altitude.
On the QDR of 075° (in the vicinity of the station) with a magnetic heading of 295°, the relative bearing on the ADF indicator is:
320°
The ILS marker identified audibly by a series of dots (6/sec.) is the:
inner marker.
Compared to the ILS, MLS has the following advantages:
Many different approaches to the same runway may be defined by a single set of ground equipment.
Full scale deflection of the localiser needle indicates that the aircraft is approximately:
2.5° offset from the localiser centreline.
An aircraft, on a heading of 180°M is on a bearing 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 with a TO indication is:
090°
The MLS frequencies and available channels are:
in the SHF band, 300 kHz frequency separation giving 200 available channels.
…………….
The MLS transmit in the SHF band (5031 MHz – 5091 MHz) with 300 kHz (0.3 MHz) spacing giving 200 available channels.
You are on a heading of 090° on the 255 radial from a VOR. You set 190° on your OBS. The deviation bar will show:
Full scale deflection left with a ‘from’ indication
The information carried by a signal emitted from a VOR is:
in what magnetic direction the signal left the VOR antenna and the identification of the station
……………..
The information carried by a signal emitted from a VOR is the magnetic direction the signal left the VOR antenna and the identification of the station.
Background Information
The VOR transmitter emits two signals, on the same carrier wave frequency:
- Reference Phase signal
- Variable Phase signal
These signals are in phase with each other along a bearing of 000°M (Magnetic North) from the VOR, i.e. the phase difference between the two signals is 000°.
On all other bearings from the station there is a phase difference between the two signals. The phase difference is equal to the magnetic bearing from the VOR, e.g. along a bearing of 045°M from the VOR, the reference phase signal leads the variable phase signal by 045° (phase difference = 045°)
The two signals are received at the aircraft on the VHF NAV receiver, which identifies the radial the aircraft is currently on from the phase difference between the two signals, and outputs this information to the cockpit display equipment.
The station identification code is also transmitted on the carrier wave.
