ATPL(A) 062 Radio NavigationRevision notes and practice questions

062 Radio NavigationFree sample, 10 questions

1. 1Electromagnetic waves in the VLF band cover which frequency range?

   1. 3-30 kHz.
   2. 30-300 kHz.
   3. 300-3000 kHz.
   4. 30-300 MHz.
   Show the answer

   Answer A. The very low frequency band runs from 3 to 30 kHz, with wavelengths of 100 to 10 km. 30 to 300 kHz is LF, 300 to 3000 kHz is MF and 30 to 300 MHz is VHF: each band is ten times higher in frequency than the one below it.

2. 2What distance will the DME display when the aircraft is at FL 360, 6 NM plan range from the DME station? For the calculation, assume: QNH is 1013 hPa; pressure altitude is true altitude.

   1. 10 NM
   2. 8 NM
   3. 6 NM
   4. 12 NM
   Show the answer

   Answer B. DME measures slant range, the straight line from the aircraft to the station. At FL360 the aircraft is 36000 ft high, which is 36000 / 6076 ≈ 5.9 NM. Slant range = √(6² + 5.9²) = √71.1 ≈ 8.4 NM, so the DME shows about 8 NM. 6 NM is the plan range the question gives, not what the DME reads.

3. 3The airborne weather radar...

   1. may receive no reflections from a thunderstorm in an area behind a heavy rain shower.
   2. has a second transmitter working on a lower frequency in order to penetrate rain showers.
   3. uses circular polarisation in order to reduce echoes of heavy showers.
   4. has the possibility to detect clear air turbulence behind a thunderstorm by measuring phase differences caused by the Doppler effect.
   Show the answer

   Answer A. Heavy rain attenuates the radar beam, and behind a strong shower too little energy may remain to produce returns from another cell. The screen then shows nothing where a thunderstorm may exist: this is the radar shadow. The radar has no second transmitter, does not use circular polarisation for this purpose, and cannot detect clear air turbulence, which contains no precipitation.

4. 4Which statement about the NAVSTAR GPS transmission frequencies L1 and L2 and their codes is correct?

   1. The C/A code is the only code available for civilian use. It is transmitted only on L1.
   2. The P code is the only code available for civilian use. It is transmitted only on L1.
   3. The C/A code is for authorised (military) use only. It is transmitted on both L1 and L2.
   4. The P code is for authorised (military) use only. It is transmitted only on L2.
   Show the answer

   Answer A. The coarse acquisition (C/A) code is the code open to civil users, and on the legacy GPS signal it is transmitted on L1 only. The precision (P) code is modulated on both L1 and L2 and is encrypted as P(Y) for authorised, mainly military, users. The trap is the P code on L2 only: it is on both frequencies, which is what lets authorised receivers remove the ionospheric delay.

5. 5Which statement is correct about the scope of the PBN concept?

   1. In the approach phases of flight, PBN is limited to operations with guidance to fly the ILS procedure.
   2. For oceanic/remote, en-route and terminal phases of flight, PBN is limited to operations with angular laterally guided operations.
   3. For oceanic/remote, en-route and terminal phases of flight, PBN accommodates both linear and angular laterally guided operations.
   4. In the approach phases of flight, PBN accommodates both linear and angular laterally guided operations.
   Show the answer

   Answer D. PBN applies to oceanic, en-route, terminal and approach operations. Outside the approach, lateral performance is linear: a fixed tolerance either side of the path. In the approach phase both kinds exist: linear, as in RNP APCH to LNAV minima, and angular, as in LPV, where the tolerance narrows towards the runway like an ILS. Angular guidance is therefore not used en route or in the terminal area.

6. 6An aircraft has no automatic temperature correction. What happens to the glide path?

   1. A warmer temperature reduces the glide path angle.
   2. Temperature has no effect on the glide path angle.
   3. Colder temperature reduces your glide path angle.
   4. A colder temperature steepens the glide path angle.
   Show the answer

   Answer C. A barometric vertical path assumes ISA temperatures. In air colder than ISA the true altitude is lower than indicated, and the error grows with height above the station, so the path actually flown is lower and flatter than published: the angle is reduced. Warm air does the opposite and steepens the path, which is why the uncompensated cold case is the dangerous one near terrain.

7. 7The BFO switch on the ADF control panel must be selected "ON" to allow the pilot to:

   1. Adjust the loop to the aural null position.
   2. Stop the loop rotation.
   3. Hear the IDENT of NDBs using NON A1A transmissions.
   4. Hear the IDENT of NDBs using NON A2A transmissions.
   Show the answer

   Answer C. An NDB using NON A1A identifies itself by keying its plain carrier on and off, so there is no audio tone to hear. The beat frequency oscillator mixes a locally generated signal with the carrier to produce an audible tone, so the BFO must be on to hear the Morse ident. A2A beacons modulate their carrier with their own tone and need no BFO.

8. 8During the descent it is important to set the AWR tilt to a higher setting. Why is this?

   1. To avoid clutter from ground returns
   2. To scan the higher altitude clouds to avoid hail
   3. To avoid scanning below the cloud layer and missing turbulence/weather
   4. During descent the AWR is not required
   Show the answer

   Answer A. As the aircraft descends, a beam that was pointing level or slightly down increasingly strikes the terrain ahead and fills the display with ground returns. Raising the tilt keeps the beam above the ground so that the weather ahead is displayed clearly. The radar remains essential in the descent, when the aircraft passes through the lower cloud layers.

9. 9By using both GPS frequencies, L1 and L2, a receiver can almost eliminate the...

   1. tropospheric propagation delay.
   2. position dilution of precision.
   3. both ionospheric and atmospheric propagation delay.
   4. ionospheric propagation delay.
   Show the answer

   Answer D. The ionosphere delays a radio signal by an amount inversely proportional to the square of its frequency, so L1 and L2 arrive with different delays. Comparing the two lets the receiver compute the ionospheric delay and remove almost all of it. The troposphere delays both frequencies by the same amount, so dual-frequency reception cannot measure it: it has to be modelled.

10. 10In PBN operations, for which phases of flight can RNAV 2 be used?

    1. En-route oceanic, en-route continental, and approach.
    2. Arrival, departure, and approach.
    3. En-route continental, arrival, and departure.
    4. En-route remote, intermediate approach, and final approach.
    Show the answer

    Answer C. RNAV 2 is intended for continental en-route routes and for arrivals and departures in the terminal area. Oceanic and remote airspace uses RNAV 10 or RNP 4, and approaches use RNP APCH or RNP AR APCH, so any option including an approach or oceanic segment is wrong.