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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:
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:
What according to ICAO Annex 10 is the range of a locator?
What according to ICAO Annex 10 is the range of a locator?
What actually happens in the ADF receiver when the BFO position is selected?
What actually happens in the ADF receiver when the BFO position is selected?
Which of the following is correct regarding the range of an NDB?
Which of the following is correct regarding the range of an NDB?
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You are on a magnetic heading of 055o and your ADF indicates a relative bearing of 325o. The QDM is:
You are on a magnetic heading of 055o and your ADF indicates a relative bearing of 325o. The QDM is:
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Which combination gives the greatest reduction in reliability of ADF:
Which combination gives the greatest reduction in reliability of ADF:
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What gives the greatest error in ADF?
What gives the greatest error in ADF?
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The nominal maximum range of an NDB with a transmitter power of 200 watts is:
The nominal maximum range of an NDB with a transmitter power of 200 watts is:
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The ICAO allocated band of frequencies for NDB is:
The ICAO allocated band of frequencies for NDB is:
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An aircraft 10 NM from a north-south coastline takes two three-position line fixes from an inland NDB. The aircraft's indicated position is:
An aircraft 10 NM from a north-south coastline takes two three-position line fixes from an inland NDB. The aircraft's indicated position is:
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Using an ADF loop aerial, the maximum signal will be received when:
Using an ADF loop aerial, the maximum signal will be received when:
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When identifying an NDB (NON A1A), it is necessary to:
When identifying an NDB (NON A1A), it is necessary to:
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Which of the following are all errors associated with ADF?
Which of the following are all errors associated with ADF?
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What action must be taken to receive a bearing from an ADF?
What action must be taken to receive a bearing from an ADF?
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Which of the following is the most significant error in ADF?
Which of the following is the most significant error in ADF?
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When using ADF (i), the accuracy is (ii) than (iii), because the surface wave is (iv):
When using ADF (i), the accuracy is (ii) than (iii), because the surface wave is (iv):
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Snow will affect ADF by:
Snow will affect ADF by:
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An NDB has a range of 50 NM with a power output of 80 watts: The power required to increase the range to 75 NM is:
An NDB has a range of 50 NM with a power output of 80 watts: The power required to increase the range to 75 NM is:
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Do all ADF systems have a sense aerial?
Do all ADF systems have a sense aerial?
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If an NDB signal is received at a range of 1000 NM:
If an NDB signal is received at a range of 1000 NM:
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The maximum errors when using ADF will occur in which of the following situations: (i) Position of the NDB (ii) Angle of cut at the coast
The maximum errors when using ADF will occur in which of the following situations: (i) Position of the NDB (ii) Angle of cut at the coast
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NDBs operate in the:
NDBs operate in the:
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When considering the use of NDB, night effect has its greatest effect during:
When considering the use of NDB, night effect has its greatest effect during:
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An aircraft over the sea will experience (i) coastal refraction effect when the radio waves cross the coastline at (ii) and the NDB is (iii):
An aircraft over the sea will experience (i) coastal refraction effect when the radio waves cross the coastline at (ii) and the NDB is (iii):
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An ADF is correctly tuned to an NDB, the needle is hunting and the signal is fading and growing louder alternately, the reason for this is:
An ADF is correctly tuned to an NDB, the needle is hunting and the signal is fading and growing louder alternately, the reason for this is:
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When converting VOR and ADF bearings to true, the variation at the (i) should be used for VOR and at the (ii) for ADF:
When converting VOR and ADF bearings to true, the variation at the (i) should be used for VOR and at the (ii) for ADF:
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Two NDBs, one 20 NM from the coast and the other 50 NM further inland. Assuming coastal refraction is the same for each, from which NDB will an aircraft flying over the sea receive the greatest error?
Two NDBs, one 20 NM from the coast and the other 50 NM further inland. Assuming coastal refraction is the same for each, from which NDB will an aircraft flying over the sea receive the greatest error?
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The allocated coverage of NDBs is:
The allocated coverage of NDBs is:
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What antennae must be used to obtain an ADF bearing?
What antennae must be used to obtain an ADF bearing?
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For long range NDBs the most common type is:
For long range NDBs the most common type is:
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RMI rose is mechanically stuck on 090 degrees. The ADF pointer indicates 225 degrees. What is the relative bearing to the beacon?
RMI rose is mechanically stuck on 090 degrees. The ADF pointer indicates 225 degrees. What is the relative bearing to the beacon?
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NDBs transmit mainly in the:
NDBs transmit mainly in the:
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The 95% accuracy for ADF bearings of an NDB by day is:
The 95% accuracy for ADF bearings of an NDB by day is:
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When receiving an NDB signal on an ADF receiver the BFO can be selected OFF for the:
When receiving an NDB signal on an ADF receiver the BFO can be selected OFF for the:
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An aircraft is tracking 060o (T) in still air. The relative bearing of an NDB is 035o at 1300. 12 min later the relative bearing is 070o. If the G/S is 180kt, what is the aircraft's distance from the NDB at 1312?
An aircraft is tracking 060o (T) in still air. The relative bearing of an NDB is 035o at 1300. 12 min later the relative bearing is 070o. If the G/S is 180kt, what is the aircraft's distance from the NDB at 1312?
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A radio beacon has a range of 10 NM. By what factor should the power be increased to achieve a range of 20 NM?
A radio beacon has a range of 10 NM. By what factor should the power be increased to achieve a range of 20 NM?
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A NDB transmits a signal pattern which is:
A NDB transmits a signal pattern which is:
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The frequency band chosen for NDBs is:
The frequency band chosen for NDBs is:
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To maintain the 314o QDR inbound to a NDB with 7o starboard drift, the heading in oM and relative bearing will be:
To maintain the 314o QDR inbound to a NDB with 7o starboard drift, the heading in oM and relative bearing will be:
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Which of the following may cause inaccuracies in ADF bearings?
Which of the following may cause inaccuracies in ADF bearings?
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On the B737-400 EHSI what happens if the selected VOR fails?
On the B737-400 EHSI what happens if the selected VOR fails?
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If the signal from a VOR is lost, how is this shown on the B737-400 EHSI display?
If the signal from a VOR is lost, how is this shown on the B737-400 EHSI display?
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An aircraft is flying on the true track 090o towards a VOR station located near the equator where the magnetic variation is 15oE. The variation at the aircraft position is 8oE. The aircraft is on VOR radial:
An aircraft is flying on the true track 090o towards a VOR station located near the equator where the magnetic variation is 15oE. The variation at the aircraft position is 8oE. The aircraft is on VOR radial:
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The frequency range of a VOR receiver is:
The frequency range of a VOR receiver is:
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An aircraft is 100 NM from a VOR facility. Assuming no error when using a deviation indicator where 1 dot = 2o deviation, how many dots deviation from the center line of the instrument will represent the limits of the airway boundary? (Assume that the airway is 10 NM wide)
An aircraft is 100 NM from a VOR facility. Assuming no error when using a deviation indicator where 1 dot = 2o deviation, how many dots deviation from the center line of the instrument will represent the limits of the airway boundary? (Assume that the airway is 10 NM wide)
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When tracking a VOR radial inbound the aircraft would fly?
When tracking a VOR radial inbound the aircraft would fly?
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(Refer to figure 062-04) An aircraft is attempting to track 186oM on an airway defined by a VOR 80 NM away. The VOR indicates the aircraft position. With these indications the aircraft is on the ___ radial and ___ the airway.
(Refer to figure 062-04) An aircraft is attempting to track 186oM on an airway defined by a VOR 80 NM away. The VOR indicates the aircraft position. With these indications the aircraft is on the ___ radial and ___ the airway.
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An aircraft is on radial 120 with a magnetic heading of 300o, the track selector (OBS) reads: 330. The indications on the Course Deviation Indicator (CDI) are fly:
An aircraft is on radial 120 with a magnetic heading of 300o, the track selector (OBS) reads: 330. The indications on the Course Deviation Indicator (CDI) are fly:
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An aircraft is on a heading of 100 degrees (m) from a VOR. To make the VOR/ILS deviation indicator needle centralize with the TO flag showing, the following bearing should be selected on the OBS:
An aircraft is on a heading of 100 degrees (m) from a VOR. To make the VOR/ILS deviation indicator needle centralize with the TO flag showing, the following bearing should be selected on the OBS:
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The basic principle of operation of a standard VOR is by:
The basic principle of operation of a standard VOR is by:
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Given: Magnetic heading 280o VOR radial 090o. What bearing should be selected on the omni-bearing selector in order to centralize the VOR deviation needle with a TO indication?
Given: Magnetic heading 280o VOR radial 090o. What bearing should be selected on the omni-bearing selector in order to centralize the VOR deviation needle with a TO indication?
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An aircraft is tracking inbound to a VOR beacon on the 105 radial. The setting the pilot should put on the OBS and the CDI indications are:
An aircraft is tracking inbound to a VOR beacon on the 105 radial. The setting the pilot should put on the OBS and the CDI indications are:
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Transmissions from VOR facilities may be adversely affected by:
Transmissions from VOR facilities may be adversely affected by:
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Given: VOR station position N61o E025o, variation 13oE. Estimated position of an aircraft N59o E025o, variation 20oE. What VOR radial is the aircraft on?
Given: VOR station position N61o E025o, variation 13oE. Estimated position of an aircraft N59o E025o, variation 20oE. What VOR radial is the aircraft on?
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An aircraft is on a VOR radial of 235o, heading 003o(M), and with the OBS set to 060. The correct indications are:
An aircraft is on a VOR radial of 235o, heading 003o(M), and with the OBS set to 060. The correct indications are:
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If an aircraft flies along a VOR radial it will follow a:
If an aircraft flies along a VOR radial it will follow a:
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What is the maximum theoretical range that an aircraft at FL 150 can receive signals from a VOR situated 609 feet above MSL?
What is the maximum theoretical range that an aircraft at FL 150 can receive signals from a VOR situated 609 feet above MSL?
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An aircraft is required to approach a VOR via the 104o radial. Which of the following settings should be made on the VOR/ILS deviation indicator?
An aircraft is required to approach a VOR via the 104o radial. Which of the following settings should be made on the VOR/ILS deviation indicator?
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What is the radial of a VOR situated at position 58o00 N 073o00 W with a magnetic variation of 32oW, if an aircraft is located at position 56o00 N 073o00 W with a magnetic variation of 28oW?
What is the radial of a VOR situated at position 58o00 N 073o00 W with a magnetic variation of 32oW, if an aircraft is located at position 56o00 N 073o00 W with a magnetic variation of 28oW?
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The VOR system is limited to about 1o of accuracy. One degree at 200 NM represents a width of:
The VOR system is limited to about 1o of accuracy. One degree at 200 NM represents a width of:
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Using a VOR outside the DOC may result in interference from:
Using a VOR outside the DOC may result in interference from:
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The antenna polar diagram of a conventional VOR:
The antenna polar diagram of a conventional VOR:
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The two signals transmitted by a conventional VOR ground station are 90o out of phase on magnetic:
The two signals transmitted by a conventional VOR ground station are 90o out of phase on magnetic:
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To convert the RMI bearings of NDBs and VORs to true bearings, the correct positions to read magnetic variation are:
To convert the RMI bearings of NDBs and VORs to true bearings, the correct positions to read magnetic variation are:
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With reference to the VOR:
With reference to the VOR:
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Which of the following statements concerning the variable, or directional, signal of a conventional VOR is correct?
Which of the following statements concerning the variable, or directional, signal of a conventional VOR is correct?
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Given: Course Deviation Indicator (CDI) for a VOR is selected to 090o. From/To indicator indicates TO. CDI needle is deflected halfway to the right. On what radial is the aircraft?
Given: Course Deviation Indicator (CDI) for a VOR is selected to 090o. From/To indicator indicates TO. CDI needle is deflected halfway to the right. On what radial is the aircraft?
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In order to plot a bearing from a VOR station, a pilot needs to know the magnetic variation:
In order to plot a bearing from a VOR station, a pilot needs to know the magnetic variation:
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The captain of an aircraft flying at FL 100 wishes to obtain weather information at the destination airfield (0 ft MSL) from the airfield's VOR. At what maximum theoretical range will it be possible to obtain this information?
The captain of an aircraft flying at FL 100 wishes to obtain weather information at the destination airfield (0 ft MSL) from the airfield's VOR. At what maximum theoretical range will it be possible to obtain this information?
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If the reference phase differs 30o with the variable phase, the radial from the VOR station will be:
If the reference phase differs 30o with the variable phase, the radial from the VOR station will be:
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Which frequency band is used by VOR transmissions?
Which frequency band is used by VOR transmissions?
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An aircraft at FL 100 should be able to receive a VOR ground station at 100 FT above MSL at an approximate maximum range of:
An aircraft at FL 100 should be able to receive a VOR ground station at 100 FT above MSL at an approximate maximum range of:
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For a conventional VOR, a phase difference of 090 deg would be achieved by flying ___ from the beacon.
For a conventional VOR, a phase difference of 090 deg would be achieved by flying ___ from the beacon.
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An airway 10 NM wide is to be defined by two VORs each having a resultant bearing accuracy of plus or minus 5.5o. In order to ensure accurate track guidance within the airway limits, the maximum distance apart for the transmitters is approximately:
An airway 10 NM wide is to be defined by two VORs each having a resultant bearing accuracy of plus or minus 5.5o. In order to ensure accurate track guidance within the airway limits, the maximum distance apart for the transmitters is approximately:
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An RMI slaved to a remote indicating compass has gone unserviceable and is locked on to a reading of 090o. The tail of the VOR pointer shows 135o. The available information from the VOR is:
An RMI slaved to a remote indicating compass has gone unserviceable and is locked on to a reading of 090o. The tail of the VOR pointer shows 135o. The available information from the VOR is:
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Study Notes
RADIO NAVIGATION - GROUND DIRECTION FINDER (D/F)
- VDF (VHF Direction Finding) requires aircraft fitted with a VHF radio for let-down procedures.
- The maximum theoretical range for a VDF facility at 325 feet for an aircraft at FL080 is 134 NM.
- An advantage of Ground/DF let-down is it only requires a VHF radio on the aircraft, minimizing equipment needs.
- The VDF approach process places responsibility for interpreting the procedure on the pilot.
- For an aircraft at FL130 and a VDF facility sited at 1024 Ft, the range is theoretically 180 NM.
- Frequency in radio terms refers to the number of complete waveforms passing a point per second.
- A QGH indicates the VDF unit’s readiness to assist an aircraft during approach, based on VDF bearings.
- VDF advantages include requiring only a VHF radio for operation, simplifying airborne equipment requirements.
- A VDF bearing provides the true bearing of the aircraft from the ground station, known as QTE.
- VDF is often used in emergencies, especially when contacting ATC on the emergency VHF frequency 121.5 MHz.
- An aircraft transmitting at 10 GHz will experience Doppler effects, possibly shifting received frequencies.
- Ground DME responders transmit at a frequency 63 MHz greater than the interrogation frequency.
- Phase difference in VOR signals: on QDM 050° with VAR 10°W, the difference measures 230°.
- VDF services can be accessed on the notified frequency for such services.
- Accuracy of VDF bearings can be affected by sky waves, duct propagation, and ground reflections.
- Range for obtaining VDF bearings is influenced by aircraft height, time of day, and surface type.
- RF signals have polarization determined by the transmitter unit, impacting aerial reception.
- A half-wave dipole aerial for 18 MHz operates effectively at 8.33 meters in length.
- A broad bandwidth increases noise; effective noise management is achieved through bandwidth reduction.
- RF signal diffraction occurs when passed over obstacles similar to wavelength, altering its propagation path.
- At 5,000 feet altitude, VHF signal reception from a sea-level transmitter can reach approximately 88.4 NM.
- Signals reception at 200 NM from a VHF transmitter can occur via duct propagation, influencing transmission reliability.
- HF frequency for effective communications should decrease at night due to atmospheric conditions.
- QTE stands for true track from the station, essential for navigation purposes.
- Ground direction finding at aerodromes utilizes VHF at civil and UHF at military aerodromes.
- Emission characteristic A3E refers to VHF communications essential for aeronautical services.
- Locator transmissions typically occur in the LF/MF frequency bands as per ICAO standards.
- Requesting QDR signals a need for magnetic bearings from a VDF station, critical for navigation accuracy.### Radio Navigation and Direction Finding
- VDF Usage: VDF (VHF Direction Finding) is employed when an aircraft declares an emergency, particularly on frequency 121.5 MHz.
- Aerial Gain: Gain measures an aerial's ability to focus power and compensate for attenuation; it's critical for effective transmission.
- Frequency-Wavelength Relationship: A frequency of 2400 KHz corresponds to a wavelength of 125 meters.
- Electromagnetic Refraction: Refers to the bending of the propagation path as electromagnetic waves pass through areas of varying electrical conductivity.
VDF Service and Accuracy
- VDF Homer Service: Provides accurate bearings on demand, typically within ±5° accuracy for up to 200 nautical miles.
- VDF Classification: A Class B bearing offers accuracy within ±5°, while Class A and Class C bear accuracy variations are ±2° and ±10°, respectively.
Frequency and Wavelength
- Decimetric Waves: These frequencies range from 300 to 3000 MHz.
- Wavelength Calculation: A radio signal of 375 KHz translates to a wavelength of 800 meters.
- Static Interference: Guaranteed protection from static interference begins at 30 MHz.
Controller Requirements
- VDF/QGH Procedures: Requires a ground operator for both VDF and QGH procedures to assist during the process.
- Refusal of Bearings: Ground DF controllers may withhold bearings if conditions are poor, which could affect accuracy and reliability.
Direction Finding Characteristics
- NDB Signals: NDBs (Non-Directional Beacons) transmit omnidirectional signals; common errors include night effects, station interference, and precipitation impacts.
- ADF Bearings: Achieved when signals are received by both sense and loop aerials; the signal polarization must also be acknowledged.
- BFO Selector: Used on ADF receivers to hear the IDENT of NDB stations that radiate a continuous wave signal.
Atmospheric Effects on Signals
- Night Effect: Most significant at dusk and dawn, leading to errors in signal reception.
- Ground Waves: LF and MF ground waves differ in effective range, with MF suffering more from atmospheric attenuation during day conditions.
Q Codes and Navigation
- Magnetic Bearing: QDR indicates a magnetic bearing from a VDF station.
- True Track: QTE provides a true track from a VDF station, crucial for navigation accuracy.
- Magnetic Heading: QDM specifies a magnetic heading to steer towards a VDF station with nil wind.
Additional Concepts
- Frequency Influence on Ground Wave Range: As frequency increases, the range of ground waves decreases, impacting communication effectiveness.
- Navigational Calculations: Understanding compass headings, magnetic variation, and relative bearings is essential for accurately determining QDR.### ADF Equipment and Operation
- ADF equipment uses a sense aerial and a loop aerial for navigation, tuned to NDBs.
- The loop aerial finds a sharp null when aligned with incoming signals, typically either at angles or line with those signals.
- ADF accuracy may suffer due to coastal refraction, particularly pronounced when the bearing crosses the coast at an acute angle.
Errors and Interference
- Quadrantal errors arise from signal bending due to aircraft metallic structures, impacting ADF reliability.
- Local thunderstorm activity notably distorts ADF bearings, presenting a significant source of inaccuracy.
- The impact of interference from other NDBs is greater during night operations due to heightened sky wave activity.
Frequency Bands and Ranges
- The ICAO frequency band for ADF receivers is 190 - 1750 kHz.
- An NDB with a power of 200 watts typically has a maximum range of 50 to 60 NM.
- Doubling the distance (from 10 NM to 20 NM) requires an increase in transmitter power by a factor of four.
NDB Transmission Characteristics
- NDBs typically transmit on frequencies such as 200 kHz and are classified by their modulation types (e.g., A1A).
- The nominal maximum range of an NDB is influenced directly by its transmitter power; increasing to 100 KW can extend range to approximately 100 NM.
Navigation Techniques
- The BFO switch on an ADF receiver is crucial for making signals audible, particularly for identifying signals from different NDB types.
- RMI (Radio-Magnetic Indicator) readings require adjustments for magnetic variation to calculate true bearings correctly.
Bearing Accuracy and Conditions
- ADF bearings should maintain a maximum error of ±5 degrees during daylight within published protection range.
- The D layer of the ionosphere does not affect NDB bearing accuracy during nighttime, signifying no distortion in signal.
Atmospheric Effects and Cloud Influence
- Cumulonimbus clouds can mislead navigation systems, particularly the ADF, which may yield false indications when in proximity.
Holding Patterns and Approach
- Inbound leg of holding patterns around an NDB necessitates flight management based on RMI indications and correct intercept angles.
- Executing a right-hand holding pattern requires understanding ADF readings and making appropriate heading adjustments.
NDB Aerial Design and Classifications
- NDB aerials are designed to maximize range by minimizing diffraction effects associated with ground waves.
- Locators can operate with varying power levels and ranges, ensuring adherence to A2A specifications for accuracy and reliability.
Air Navigation Protocols
- ADF plays a critical role in aiding pilot navigation, ensuring flight safety and efficiency.
- Proper interpretation of ADF bearings is essential for successful navigation, particularly in complex environments with multiple ground stations.
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Description
Test your knowledge on VHF Direction Finding (VDF) and its principles in radio navigation. This quiz covers the operational range, advantages, and pilot responsibilities associated with Ground Direction Finding. Perfect for aviation students and enthusiasts.
