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DGCA Air Navigation: Mls Questions

53 exam-style Mls questions for the DGCA Air Navigationpaper (CPL & ATPL). The first 12 are free below with answers and explanations — sign up free to practise all of them with progress tracking.

  1. Q1

    The azimuth transmitter of a Microwave Landing System (MLS) provides a fan shaped horizontal approach zone which is usually:

    • A+ or - 40° of the runway centre-line
    • B+ or - 50° of the runway centre-line
    • C+ or - 60° of the runway centre-line
    • D+ or - 30° of the runway centre-line
    Show answer

    Correct answer: A. + or - 40° of the runway centre-line

    An MLS azimuth transmitter sweeps a fan-shaped sector of plus or minus 40 degrees about the runway centreline, giving far wider coverage than an ILS localizer.

  2. Q2

    Which one of the following is an advantage of a Microwave Landing System (MLS) compared with an Instrument Landing System (ILS)?

    • AIt is insensitive to geographical site and can be installed at sites where it is not possible to use an ILS
    • B It does not require a separate azimuth (localiser) and elevation (azimuth) transmitter
    • CThe installation does not require to have a separate method (marker beacons or DME) to determine range
    • D There is no restriction on the number of ground installations that can be operated because there is an unlimited number of frequency channels available
    Show answer

    Correct answer: A. It is insensitive to geographical site and can be installed at sites where it is not possible to use an ILS

    A major MLS advantage is that it is far less sensitive to the surrounding terrain and reflections than ILS, so it can be sited where an ILS could not provide a usable beam.

  3. Q3

    MLS installations notified for operation, unless otherwise stated, provide azimuth coverage of:

    • A + or - 40° about the nominal courseline out to a range of 20 NM
    • B+ or - 20° about the nominal courseline out to a range of 20 NM
    • C + or - 40° about the nominal courseline out to a range of 30 NM
    • D + or - 20° about the nominal courseline out to a range of 10 NM
    Show answer

    Correct answer: A. + or - 40° about the nominal courseline out to a range of 20 NM

    Unless otherwise notified, an MLS provides azimuth coverage of plus or minus 40 degrees about the nominal courseline out to a range of 20 NM.

  4. Q4

    In which frequency band does the Microwave Landing System (MLS) operate?

    • A SHF
    • BEHF
    • C VHF
    • D UHF
    Show answer

    Correct answer: A. SHF

    MLS operates in the SHF band, around 5 GHz, which allows its narrow scanning beams and wide coverage.

  5. Q5

    Which one of the following methods is used by a Microwave Landing System (MLS) to indicate distance from the runway threshold?

    • AA DME co-located with the MLS transmitters
    • B Timing the interval between the transmission and reception of primary radar pulses from the aircraft to MLS station
    • C Measurement of the frequency shift between the MLS azimuth and elevation transmissions
    • D Timing the interval between the reception of sequential secondary radar pulses from the MLS station to the aircraft
    Show answer

    Correct answer: A. A DME co-located with the MLS transmitters

    MLS provides range by means of a precision DME co-located with the azimuth and elevation transmitters, giving continuous distance to the threshold.

  6. Q6

    Which one of the following correctly lists the major ground based components of a Microwave Landing System (MLS)?

    • A Separate azimuth and elevation transmitters, DME facility
    • BSeparate azimuth and elevation transmitters, outer and middle marker beacons
    • CCombined azimuth and elevation transmitter, DME facility
    • DCombined azimuth and elevation transmitter, outer and inner marker beacons
    Show answer

    Correct answer: A. Separate azimuth and elevation transmitters, DME facility

    MLS uses separate ground transmitters for azimuth and for elevation guidance, together with a co-located precision DME to provide continuous range, allowing curved and segmented approach paths.

  7. Q7

    The coverage of MLS is …… either side of the centreline to a distance of

    • A40°, 40 nm
    • B40° 20 nm
    • C20°, 20 nm
    • D20°, 40 nm
    Show answer

    Correct answer: B. 40° 20 nm

    This Explanation is Coming Soon

  8. Q8

    Distance on MLS is measured by:

    • Ameasuring the time taken for the primary radar pulse to travel from the MLS transmitter to the aircraft receiver
    • Bmeasuring the time taken for the secondary radar pulse to travel from the MLS transmitter to the aircraft receiver
    • Cphase comparison between the azimuth and elevation beams
    • Dco-located DME
    Show answer

    Correct answer: D. co-located DME

    This Explanation is Coming Soon

  9. Q9

    Which of the following is an advantage of MLS?

    • Acan be used in inhospitable terrain
    • Buses the same aircraft equipment as ILS
    • Chas a selective access ability
    • Dis not affected by heavy precipitation
    Show answer

    Correct answer: A. can be used in inhospitable terrain

    This Explanation is Coming Soon

  10. Q10

    The frequency band of MLS is:

    • AUHF
    • BVHF
    • CSHF
    • DVLF
    Show answer

    Correct answer: C. SHF

    This Explanation is Coming Soon

  11. Q11

    The azimuth transmitter of a Microwave Landing System (MLS) provides a fan shaped horizontal approach zone which is usually:

    • A+ or - 40° of the runway centre-line
    • B+ or - 50° of the runway centre-line
    • C + or - 60° of the runway centre-line
    • D + or - 30° of the runway centre-line
    Show answer

    Correct answer: A. + or - 40° of the runway centre-line

    The MLS azimuth transmitter radiates a fan-shaped horizontal sector normally covering plus or minus 40 degrees either side of the runway centreline. This wide proportional coverage is one of its advantages over the fixed ILS localiser.

  12. Q12

    Which one of the following is an advantage of a Microwave Landing System (MLS) compared with an Instrument Landing System (ILS)?

    • AIt is insensitive to geographical site and can be installed at sites where it is not possible to use an ILS
    • BIt does not require a separate azimuth (localiser) and elevation (azimuth) transmitter
    • CThe installation does not require to have a separate method (marker beacons or DME) to determine range
    • D There is no restriction on the number of ground installations that can be operated because there is an unlimited number of frequency channels available
    Show answer

    Correct answer: A. It is insensitive to geographical site and can be installed at sites where it is not possible to use an ILS

    A major MLS advantage is that it is far less sensitive to the surrounding terrain and reflections, so it can be sited at locations where an ILS could not give a usable beam. This siting flexibility is a key improvement over ILS.

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