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Radio Navigation - Ground D/F Quiz
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Radio Navigation - Ground D/F Quiz

Created by
@CourageousCaesura

Questions and Answers

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:

  • Greater from the beacon that is 50 NM inland (correct)
  • Greater from the beacon that is 20 NM inland
  • The same from both beacons when the aircraft is on a relative bearing of 180o and 360o
  • The same from both beacons when the aircraft is on a relative bearing of 090o and 270o

    • What according to ICAO Annex 10 is the range of a locator?

  • 50 - 100 NM
  • 10 - 25 NM (correct)
  • 25 - 50 NM
  • 100 - 300 NM

    • 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 (correct)
  • The BFO circuit is de-activated
  • The BFO circuit is activated, and the receiver accepts only A1A modulated signals
  • The BFO circuit oscillates at an increased frequency in order to allow identification of A2A NDBs

    • Which of the following is correct regarding the range of an NDB?

    <p>Aircraft height is not limiting for the reception of signals from the NDB</p> Signup and view all the answers

    You are on a magnetic heading of 055o and your ADF indicates a relative bearing of 325o. The QDM is:

    <p>020o</p> Signup and view all the answers

    Which combination gives the greatest reduction in reliability of ADF:

    <p>Night effect; Static interference; Quadrantal error</p> Signup and view all the answers

    What gives the greatest error in ADF?

    <p>Static interference from thunderstorms</p> Signup and view all the answers

    The nominal maximum range of an NDB with a transmitter power of 200 watts is:

    <p>40 to 45 NM</p> Signup and view all the answers

    The ICAO allocated band of frequencies for NDB is:

    <p>200 - 1750 KHz</p> Signup and view all the answers

    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:

    <p>Nearer to the coastline than its actual position</p> Signup and view all the answers

    Using an ADF loop aerial, the maximum signal will be received when:

    <p>The loop is in line with the NDB aerial</p> Signup and view all the answers

    When identifying an NDB (NON A1A), it is necessary to:

    <p>Turn the BFO on</p> Signup and view all the answers

    Which of the following are all errors associated with ADF?

    <p>Mountain effect, station interference, static interference</p> Signup and view all the answers

    What action must be taken to receive a bearing from an ADF?

    <p>Both the loop and sense aerials must receive the signal</p> Signup and view all the answers

    Which of the following is the most significant error in ADF?

    <p>Static from Cb</p> Signup and view all the answers

    When using ADF (i), the accuracy is (ii) than (iii), because the surface wave is (iv):

    <p>(i) by night; (ii) less; (iii) by day; (iv) contaminated by sky waves</p> Signup and view all the answers

    Snow will affect ADF by:

    <p>Having no effect</p> Signup and view all the answers

    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:

    <p>180 watts</p> Signup and view all the answers

    Do all ADF systems have a sense aerial?

    <p>Always</p> Signup and view all the answers

    If an NDB signal is received at a range of 1000 NM:

    <p>It is a sky wave and is inaccurate</p> Signup and view all the answers

    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

    <p>(i) Well inland; (ii) 20o</p> Signup and view all the answers

    NDBs operate in the:

    <p>LF and MF bands</p> Signup and view all the answers

    When considering the use of NDB, night effect has its greatest effect during:

    <p>At dawn and dusk</p> Signup and view all the answers

    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):

    <p>(i) Less; (ii) 90o; (iii) Near the coast</p> Signup and view all the answers

    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:

    <p>The required ground wave is being contaminated by sky waves</p> Signup and view all the answers

    When converting VOR and ADF bearings to true, the variation at the (i) should be used for VOR and at the (ii) for ADF:

    <p>(i) Station; (ii) aircraft</p> Signup and view all the answers

    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?

    <p>The NDB at 50 NM</p> Signup and view all the answers

    The allocated coverage of NDBs is:

    <p>190 - 1750 KHz</p> Signup and view all the answers

    What antennae must be used to obtain an ADF bearing?

    <p>Loop and sense</p> Signup and view all the answers

    For long range NDBs the most common type is:

    <p>LF NON A1A</p> Signup and view all the answers

    RMI rose is mechanically stuck on 090 degrees. The ADF pointer indicates 225 degrees. What is the relative bearing to the beacon?

    <p>135 degrees</p> Signup and view all the answers

    NDBs transmit mainly in the:

    <p>MF band</p> Signup and view all the answers

    The 95% accuracy for ADF bearings of an NDB by day is:

    <p>±7o</p> Signup and view all the answers

    When receiving an NDB signal on an ADF receiver the BFO can be selected OFF for the:

    <p>Ident signal on NON A2A</p> Signup and view all the answers

    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?

    <p>36 NM</p> Signup and view all the answers

    A radio beacon has a range of 10 NM. By what factor should the power be increased to achieve a range of 20 NM?

    <p>4</p> Signup and view all the answers

    A NDB transmits a signal pattern which is:

    <p>Omni-directional</p> Signup and view all the answers

    The frequency band chosen for NDBs is:

    <p>Upper LF and lower MF</p> Signup and view all the answers

    To maintain the 314o QDR inbound to a NDB with 7o starboard drift, the heading in oM and relative bearing will be:

    <p>B – 127; 007</p> Signup and view all the answers

    Which of the following may cause inaccuracies in ADF bearings?

    <p>Lack of failure warning, station interference, static interference</p> Signup and view all the answers

    On the B737-400 EHSI what happens if the selected VOR fails?

    <p>The deviation bar is removed</p> Signup and view all the answers

    If the signal from a VOR is lost, how is this shown on the B737-400 EHSI display?

    <p>By removal of the deviation bar and pointer</p> Signup and view all the answers

    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:

    <p>255o</p> Signup and view all the answers

    The frequency range of a VOR receiver is:

    <p>108 to 117.95 MHz</p> Signup and view all the answers

    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)

    <p>1.5</p> Signup and view all the answers

    When tracking a VOR radial inbound the aircraft would fly?

    <p>A great circle track</p> Signup and view all the answers

    (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.

    <p>001o outside</p> Signup and view all the answers

    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:

    <p>Left with TO showing</p> Signup and view all the answers

    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:

    <p>280 degrees</p> Signup and view all the answers

    The basic principle of operation of a standard VOR is by:

    <p>Phase comparison between a 108 Mhz reference signal and a 30 Hz variable signal</p> Signup and view all the answers

    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?

    <p>270o</p> Signup and view all the answers

    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:

    <p>285, TO</p> Signup and view all the answers

    Transmissions from VOR facilities may be adversely affected by:

    <p>Uneven propagation over irregular ground surfaces</p> Signup and view all the answers

    Given: VOR station position N61o E025o, variation 13oE. Estimated position of an aircraft N59o E025o, variation 20oE. What VOR radial is the aircraft on?

    <p>167o</p> Signup and view all the answers

    An aircraft is on a VOR radial of 235o, heading 003o(M), and with the OBS set to 060. The correct indications are:

    <p>TO: ½ Scale deflection to the left</p> Signup and view all the answers

    If an aircraft flies along a VOR radial it will follow a:

    <p>Great circle track</p> Signup and view all the answers

    What is the maximum theoretical range that an aircraft at FL 150 can receive signals from a VOR situated 609 feet above MSL?

    <p>184 NM</p> Signup and view all the answers

    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?

    <p>104o with the FROM flag showing</p> Signup and view all the answers

    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?

    <p>212</p> Signup and view all the answers

    The VOR system is limited to about 1o of accuracy. One degree at 200 NM represents a width of:

    <p>3.5 NM</p> Signup and view all the answers

    Using a VOR outside the DOC may result in interference from:

    <p>other beacons</p> Signup and view all the answers

    The antenna polar diagram of a conventional VOR:

    <p>Rotates at 30 revolutions per second</p> Signup and view all the answers

    The two signals transmitted by a conventional VOR ground station are 90o out of phase on magnetic:

    <p>east</p> Signup and view all the answers

    To convert the RMI bearings of NDBs and VORs to true bearings, the correct positions to read magnetic variation are:

    <p>beacon position, aircraft position</p> Signup and view all the answers

    With reference to the VOR:

    <p>Failure of the monitor will cause the beacon to cease its ident</p> Signup and view all the answers

    Which of the following statements concerning the variable, or directional, signal of a conventional VOR is correct?

    <p>The rotation of the variable signal at a rate of 30 times per second gives it the characteristics of a 30 Hz amplitude modulation</p> Signup and view all the answers

    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?

    <p>275</p> Signup and view all the answers

    In order to plot a bearing from a VOR station, a pilot needs to know the magnetic variation:

    <p>at both the VOR and aircraft</p> Signup and view all the answers

    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?

    <p>123 NM</p> Signup and view all the answers

    If the reference phase differs 30o with the variable phase, the radial from the VOR station will be:

    <p>030o</p> Signup and view all the answers

    Which frequency band is used by VOR transmissions?

    <p>VHF</p> Signup and view all the answers

    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:

    <p>135 NM</p> Signup and view all the answers

    For a conventional VOR, a phase difference of 090 deg would be achieved by flying ___ from the beacon.

    <p>east</p> Signup and view all the answers

    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:

    <p>105 NM</p> Signup and view all the answers

    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:

    <p>Radial 135o, relative bearing unknown</p> Signup and view all the answers

    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.
    • 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.

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