AWR - Dgca question bank for pilots

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#1. Airborne weather radar system use a wavelength of approximately 3 cm in order to:

Transmit at a higher pulse repetition frequency for extended range.

Obtain optimum use of the Cosecant squared beam.

Detect the smaller cloud formations as well as large.

Detect the larger water droplets.

#2. The ISO-ECHO facility of an airborne weather radar is provided in order to:

Detect areas of possible severe turbulence in cloud.

Give an indication of cloud tops.

Inhibit unwanted ground returns.

Extend the mapping range.

#3. In the MAPPING MODE the airborne weather radar utilises a:

Fan shaped beam effective up to a range of 15 NM.

Fan shaped beam effective up to a maximum of 50 NM to 60 NM range.

Pencil beam to a maximum range of 60 NM.

Pencil beam effective from zero to 150 NM.

#4. Which of the following cloud types is most readily detected by airborne weather radar when using the weather beam?

Cirrocumulus.

Cumulus.

Stratus.

Altostratus.

#5. In which mode of operation does the aircraft weather radar use a cosecant radiation pattern?

CONTOUR.

WEATHER.

MAPPING.

MANUAL.

#6. In an Airborne Weather Radar that has a colour cathode ray tube (CRT) the areas of greatest turbulence are indicated on the screen by:

Colour zones being closest together.

Blank iso-echo areas where there is no colour.

Large areas of flashing red colour.

Iso-echo areas, which are, coloured black.

#7. Which of the following is a complete list of airborne weather radar antenna stabilisation axes?

Roll, pitch and yaw.

Pitch and yaw.

Roll and pitch.

Roll and yaw.

#8. In an Airborne Weather Radar that has a colour cathode ray tube (CRT) increasing severity of rain and turbulence is generally shown by a change of colour from:

Green to yellow to red.

Yellow to amber to blue.

Green to red to black.

Yellow to orange to red.

#9. A frequency of 10 GHz is considered to be the optimum for use in airborne weather radar system because:

Greater detail can be obtained at the more distant ranges of the smaller water droplets.

The larger water droplets will give good echoes and the antenna can be kept relatively small.

Static interference is minimised

Less power output is required in the mapping mode

#10. In general the operation of airborne weather radar equipment on the ground is:

Only permitted with certain precautions, to safeguard health of personnel and to protect equipment.

Permitted anywhere

Totally prohibited

Unrestrictedly permitted in aerodrome maintenance areas

#11. The pencil shaped beam of an airborne weather radar is used in preference to the mapping mode for the determination of ground features:

Beyond 100 NM because insufficient antenna tilt angle is available with the Mapping mode.

Beyond 150 NM because the wider beam gives better definition

When approaching coast-lines in polar regions

Beyond 50 to 60 NM because more power can be concentrated in the narrower beam.

#12. A frequency of airborne weather radar is:

9375 MHz.

9375 GHz.

9375 kHz.

93.75 MHz.

#13. A weather radar, set to the 100 NM scale, shows a squall at 50 NM. By changing the scale to 50 NM, the return on the radar screen should:

Increase in area and appear nearer to the bottom of the screen

Increase in area and move to the top of the screen

Decrease in area but not change in position on the screen.

Decrease in area and move to the top of the screen

#14. In weather radar the use of a cosecant beam in ‘Mapping’ mode enables:

Better reception of echoes on contrasting terrain such as ground to sea.

A greater radar range to be achieved.

Higher definition echoes to be produced giving a clearer picture.

Scanning of a large ground zone producing echoes whose signals are practically independent of distance.

#15. In Airborne Weather Radar (AWR), the main factors which determine whether a cloud will be detected are:

Size of the water drops and the wavelength/frequency used.

Range from cloud and the wavelength/frequency used.

Size of the water droplets and the diameter of the scanner.

Rotational speed of radar scanner and the range from cloud.

#16. In Airborne Weather Radar (AWR), the main factors which determine whether a cloud will be detected are:

Rotational speed of radar scanner.

Diameter of radar scanner.

Wavelength/frequency used.

Range from cloud.

#17. In order to ascertain whether a cloud return on an Aircraft Weather Radar (AWR) is at or above the height of the aircraft, the tilt control should be set to? (Assume a beam width of 5°)

2.5° up.

0°.

2.5° down.

5° up.

#18. When switching on the weather radar, after start-up, a single very bright line appears on the screen. This means that the?

Transmitter is faulty.

Scanner is not rotating.

Scanning of the cathode ray tube is faulty.

Receiver is faulty.

#19. Which of the following lists phenomena that CANNOT be detected by weather radar?

Dry hail; clear air turbulence

Snow; clear air turbulence

Clear air turbulence; turbulence in cloud with precipitation

Snow; turbulence in clouds with preciptation.

#20. The “gain” control knob of an AWR adjusts?

The power level of the transmitted energy is made dependent on the selected range.

The brightness of the display.

The automatic gain control of the AWR is activated.

The receiver sensitivity in order to achieve optimum target acquisition.

#21. Airborne Weather Radars are generally based on the use of?

Secondary radar in the SHF band.

Primary radar in the UHF band.

Primary radar in the SHF band.

Secondary radar in the VHF band.

#22. In the MAPPING MODE the airborne weather radar utilises a?

Fan shaped beam effective up to a range of 150 nm.

Fan shaped beam effective up to a maximum range of 50 nm to 60 nm.

Pencil beam effective from zero to 150 nm.

Pencil beam effective to a maximum range of 60 nm,

#23. In Airborne Weather Radar (AWR) the main factors that determine whether or not a cloud will be detected are?

Range to the cloud, wavelength/frequency used.

Size of the water droplets and the diameter of the radar scanner.

Size of the water droplets, and the wavelength/frequency used.

Rotational speed of the radar scanner, range from cloud.

#24. In order to ascertain whether a cloud return on an Aircraft Weather Radar (AWR) is at or above the height of the aircraft, the tilt control should be set to (assume a beam width of 5 degrees)?

2.5 degrees down.

2.5 degrees up.

5 degrees up.

0 degrees.

#25. In an Airborne Weather Radar the areas of greatest turbulence are usually indicated on the screen by?

Colour zones of red or magenta.

Blank areas where there is no colour.

Colour zones of green or yellow.

Areas which are coloured black.

#26. To improve the detection of precipitation area(s) in e.g. Thunderstorms, in which the top of the cloud lies at or slightly above the level of flight?

The tilting setting should be lower when the aircraft climbs to a higher altitude.

The tilting setting should be higher when the aircraft climbs to a higher altitude

The tilting setting should be higher when the selected range decreases.

The tilting setting should be lower when the selected range increase..

#27. Which statements relating to the stabilization system of airborne weather radar antennae is true?

They are stabilized with respect to the pitch, roll and yaw axes.

The are stabilized with respect to the yaw axis, but not with respect to the pitch and roll axes.

They are stabilized with respect to the pitch and roll axes but not with respect to the yaw axis.

The pilot can choose the axes of stabilization with the system's stabilization selector switch.

#28. Airborne Weather Radar has been primarily developed to detect?

Areas of wind sheer and severe aircraft icing.

Areas of severe clear air turbulence.

The kinds of precipitation, which are usually accompanied by turbulence.

All kinds of frozen precipitation such as hail, snow and graupel.

#29. The antennae of modern airborne weather radars are stabilized by means of?

Mercury swiches.

Inputs from the aircraft's atitude system.

Artificial gravity switches.

Feedback from the antenna accelerometers.

#30. The heaviest turbulence is likely t be encountered?

Where the area of heaviest precipitation is closest to the edge of the thunderstorm cell.

About half way between two thunderstorm cells.

In the very core of a thunderstorm cell.

In the area of heaviest precipitation.

#31. When using airborne weather radar in the mapping mode in polar areas one runs the risk?

Of getting a distorted because of the ice reflections.

Of aurora borealis (polar light) causing false returns.

Of understmating distance because the cold seawater is causing super refraction.

Of mistaking the edge of coastal ice off shore for the real coastline.

#32. The pictures in the diagram are showing an aircraft’s position with respect to some thunderstorm cells and the image the pilot is getting from the radar. To detect this “blind alley” the pilot should?

Select the cosecant square beam fro better alley detection.

Switch over from normal to X mode.

Initiate a steep climb.

Increase the range setting of the radar.

#33. Is is possible for weather radar to be operated on the ground?

No, never.

Yes, always.

Yes, if operating within regulations and guidelines.

Only whilst taxling

#34. In which frequency band do most Airborne Weather radars operate?

VHF.

UHF.

SHF.

EHF.

#35. The theoretical maximum range for an airborne weather radar is determined by the?

Pulse length.

Beam width.

Pulse repetition frequency.

Carrier wave frequency.

#36. On the airborne weather radar display in WX mode, different colours use used?

To display ground height differences.

To display echoes from other aircraft.

To display different intensity of precipitation.

To display clouds, indicating different levels of visibility.

#37. Ground checks of AWR are?

Allowed under specific health and safety regulations.

Allowed only when the aircraft has undergone major servicing.

Unrestricted.

Prohibited at all times.

#38. The airborne weather radar (AWR) cannot detect?

Snow.

Wet hail.

Dry hail.

Moderate rain.

#39. Which of the following list of phenomena are least likely to be detect by airborne weather radar?

Clear air turbulence.

Precipiation.

Turbulence in cloud that has precipitation.

Wet snow and turbulence in cloud that has precipitation.

#40. While using the AWR in the weather mode, the strongest returns on the screen indicates?

Areas of severe icing.

Areas of probable windshear.

Areas of high concentration of large water droplets.

Areas of severe turbulence.

#41. On a colour airborne weather radar, a bright red echo indicates?

Strong rising air currents.

An area of extreme turulence.

An area of strong windshear.

Heavy concentrations of liquid/solid water.

#42. The ISO-ECHO feature of an airborne weather radar can be used to detect?

CAT.

Wake turbulence.

Turbulence in cloud.

Areas of possible turbulence is cloud.

#43. On the AWR display the most severe turbulence will be shown?

By steep colour gradients.

In flashing red.

By a black hole.

Alternating red and white stripes.

#44. Airborne weather radar uses a particularly high frequency radar signal, at 9 to 12 GHz, in order to?

Get good returns from droplets of water and other sorts of precipitation.

Get the most accurate range and bearing inforation.

Make it possible to present a colour display of the weather situation.

Al of the answers in this question are correct.

#45. An airborne weather radar unit transmits a 5 degrees beam from a parabolic dish aerial reflector assembly. If the wavelength is 4 cm, the diameter of the dish is?

20 cm.

56 cm.

87.5 cm

87.5 in.

#46. An airborne weather radar unit transmits a 4 degrees beam from a parabolic dish aerial reflector assembly. If the wavelength is 3 cm, the diameter of the dish is?

20 in.

20 cm.

52.5 in.

52.5 cm.

#47. An airborne weather radar, with a beam width of 4 degrees in azimuth, is being used in the mapping mode. At what maximum range will it be able to detect a 1 nm wide opening in a sea cliff?

4 nm.

15 nm.

45 nm.

60 nm.

#48. The tilt angle on the AWR at which an active cloud just disappears from the screen is 4 degrees up. If the beam width is 5 degrees and the range to the cloud is 40 nm use the 1 in 60 rule to calculate the approximate height of the cloud relative to the aircraft?

4000 ft above.

4000 ft below.

6000 ft above.

6000 ft below.

#49. An aircraft flying at 25 00 feet is equipped with AWR. The beam width is 5 degrees. With the radar tilted 3.5 degrees up, the radar is showing top of a cloud return at 105 nm. The approximate height of the cloud is.

14 300 ft.

25 600 ft.

30 300 ft.

35 600 ft.

This type of question is best solved by calculating the height of the cloud top relative to the aircraft then adding this to the aircraft height. Although the question does not specifically state this, assume that the top of the cloud is just visible at the bottom of the radar screen.

The beam is 5 degrees wide so it extends 2.5 degrees above and below its centreline.
So with the centreline of the beam tilted 3.5 degrees up the bottom of the beam will be tilted at an angle of 3.5 degrees – 2.5 degrees = 1 degrees up.

The 1 in 60 rule as applied to this type of question states that:
Height above aircraft in nm = (angle in degrees × distance to cloud in nm) / 60

Inserting the data provided in the question gives:
Height above aircraft in nm = (1 degrees × 105 nm) / 60 = 1.75 nm.

Multiplying the 1.75 nm by 6080 ft/nm converts this into 10640 feet.

So the cloud top is 10640 feet above the aircraft.

Adding this to the aircraft height gives a cloud height of
10640 ft + 25000 ft = 35640 ft.
The closest option to this is 35600 ft.

#50. In an AWR with a 5 degrees beam width how do you orient the scanner to receive returns from clouds that are at or below your level?

2.5 degrees down tilt.

2.5 degrees up tilt.

5 degrees down tilt.

0 degrees tilt.

#51. The airborne weather radar is using a 5 degree beam. The cloud is detected at a range of 60 nm. If the scanner is tilted up to 5 degrees, the cloud disappears. Using trigonometry to determine the height of the tops of the cloud, in relation to the aeroplanes cruising level, select the nearest answer from the following?

15900 ft above the aircraft.

15900 below the aircraft.

31900 ft above the aircraft.

31900 ft below the aircraft.

#52. An airborne weather radar is using a 3 degrees beam. A cloud is detected at a range of 40 nm, If the scanner is tilted up to 3 degrees the cloud disappears. The top of the cloud, in relation to the aeroplane’s cruising level is approximately?

At the same level.

6000 ft above the level.

12000 ft above the level.

18000 ft above the level.

#53. What frequency is typical chosen for AWR systems?

9375 kHz.

93.75 MHz. (93 decimal 5 kHz).

93.375 GHz. (9 decimal 375 GHz).

93.75 GHz. (93 decimal 75 kHz).

#54. The AWR can be used on the ground provided: 1. The aircraft is clear of personnel, buildings and vehicles. 2. The conical beam is selected. 3. Maximum up tilt is selected. 4. The AWR must never be operated on the ground.

1, 2.

2, 3.

1, 2, 3.

The operation of airborne weather radar on the ground imposes the following risks:

Risk of injury to personnel in the vicinity.
Risk of ignition of fuel vapours in the vicinity.
Risk to damage to AWR caused by the very strong returns that will be received from reflective objects in the vicinity.

But if there is a known risk of thunderstorms and turbulence in the climb out area it is a sensible precaution to test the AWR before take-off. To minimise these risks the ground testing of AWR is permitted, but it must be carried out in accordance with specific health and safety regulations. Of the options listed in this question options 1, 2 and 3 are those most likely to be included in such regulations.

#55. The cosecant squared beam is used for mapping in the AWR because?

It allows cloud detection to be effected while mapping.

A greater range can be achieved.

A larger area of ground is illuminated by the beam.

A wider beam is produce din azimuth to give a greater coverage.

#56. On a weather radar, the greatest turbulence is likely in an area where targets are?

Coloured red.

Coloured magenta.

Show a clearly defined hole.

Show a rapid gradient of change from magenta to yellow.

#57. Weather radar is used by the pilot to assist in the?

Detection of other aircraft through clouds.

Detection and avoidance of potentially turbulent cloud cells.

Detection and avoidance of turbulence.

Detection and determination of a route through active cloud formations.

#58. The stabilisation of the weather radar aerial is effective?

For up to +/- 5 degrees in pitch and roll.

For up to +/- 20 degrees of combined pitch and roll.

For up to +/- 30 degrees of combined pitch and roll.

For up to +/- 40 degrees of combined pitch and roll.

#59. On an AWR the sequence of colours indicating increasing water droplet size is?

Blue, green, red.

Green, Yellow, red.

Black, amber, red.

Blue, amber, red.

#60. The colours used on a conventional AWR to indicate increasing intensity of returns are?

Blue, Green, Red.

Green, Amber, Red.

Green, Yellow, Orange.

Blue, Amber, Red.

#61. A height ring is used?

As a range marker.

As a zero point for range measurement.

To determine that the weather radar is functioning.

To determine the exact aeroplane height above the surface.

#62. A side lobe from an aerial of a weather radar may produce an echo on the screen known as a “height ring”. The pilot can use this?

As a range marker.

To determine the aeroplane's height above the surface.

As a zero point for range measurement.

To determine that the weather radar is functioning.

#63. The main factors, which affect whether an AWR will detect a cloud, are?

The size of the water droplets and the range to the cloud.

The scanner rotation rate and the wavelength/frequency.

The size of the water droplets and the wavelength/frequency.

The size of the water droplets and the diameter of the antenna reflector.

#64. The ISO-ECHO circuit is incorporated in the AWR?

To display areas of turbulence.

To allow ground mapping.

To alert pilots to the presence of cloud.

To allow simultaneous mapping and detection of clouds.

#65. When the airborne weather radar is operating in its primary mode, to detect precipitation?

The radar beam is a cosecant beam.

The radar beam is pencil shaped.

Maximum tilt on the aerial will often be used.

The range will be limited, compared to the range obtainable in the ground mapping mode.

#66. Airborne weather radars use a frequency of approximately 9 GHz because?

The frequency penetrates cloud quite easily enabling good mapping of ground feature in the mapping mode.

The short wavelength allows signals to be reflected from cloud water droplets of all sizes.

The wavelength is such reflections are obtained only from larger water droplets.

It has a short wavelength, so producing higher frequency returns.

#67. When using the AWR to detect long range ground features the most suitable mode of operation or beam selected would be?

The manual mode.

The mapping mode.

The contour mode.

The fan shaped beam.

#68. Using the airborne weather radar, before take-off?

The gain control should be adjusted according to the light conditions expected after take-off.

The contract control should be adjusted to maximum contrast.

The radar transmitter should not be operated when personnel are observed in the sector ahead of the aircraft.

The antenna tilt control should be set to maximum negative tilt.

#69. If the AWR transmitter is to be switched on before take-off the scanner should be tilted up with?

The weather mode selected.

The mapping mode selected.

Either of the modes selected.

none of the above.

#70. AWR in the ______ Mode progressively _ As distances _______ To equalise screen brightness?

Weather, decreases gain, increases.

Weather, increases power, decreases.

Mapping, increases gain, decreases.

Mapping, decreases power, decreases.

#71. The airborne weather radar uses the following wavelength?

Myriametic.

Metric.

Hectometric.

Centimetric.

#72. Before commencing a flight the weather radar should?

Be kept at stand-by until line-up with the runway.

Not be switched on until clear of buildings.

Be switched to stand-by, but not used until airborne.

Be switched to a range function after push-back to make sure it is functioning.

#73. The use of AWR on the ground is?

Not permitted.

Permitted provided reduced power is used.

Permitted provided special precautions, to safeguard personnel and equipment.

Only permitted to assist movement in low visibility conditions.

#74. In an AWR with a colour CRT areas of greater turbulence are indicated by?

Iso-echo areas coloured black.

Large areas of flashing red.

Iso-echo areas with no colour.

Most rapid change of colour.

#75. AWR contour mode is used for?

Identifying areas of maximum turbulence within a cloud.

Identifying rain bearing clouds.

Shorts range mapping.

Long range mapping.

Finish