Weather Radar Part 2

Question 1

The two types of beams available -

Which is used for what purposes?

Answer 1

1. Conical or pencil-shaped beam
2. Cosecant or fan-shaped beam

Conical beam is used for weather and long range mapping >60nm
Cosecant for shorter range mapping

Question 2

In relation to beams, shorter wavelengths will =

Answer 2

narrower beams

Question 3

The optimum AWR wavelength?

Answer 3

3cm

Question 4

Reflective levels of weather in order -

Answer 4

1. Wet hail
2. Rain
3. Ice crystals
4. Wet snow
5. Dry hail
6. Dry snow

Question 5

The areas of greatest potential turbulence occur where the colour zones are -

Answer 5

Closest together

Question 6

Also turbulence is associated with the following shapes are to be avoided -

Answer 6

U-shapes, Fingers, Scalloped edges and Hooks.

Question 7

The maximum practical range for weather and for navigation is in the region of -

Answer 7

150 NM

Question 8

Tilt Control:

This control enables the radar beam to be tilted from the horizontal within __° UP (+) and __° DOWN (-).

Answer 8

This control enables the radar beam to be tilted from the horizontal within 15° UP (+) and 15° DOWN (-).

Question 9

Signal amplification is adjustable via the adjacent MANUAL GAIN knob for the -

Answer 9

Cosecant beam(MAP beam)

Question 10

The weather radar tilt should be tilted up -

And down -

Answer 10

When the selected range increases or the altitude decreases

When the selected range decreases or when the altitude increases

Question 11

The minimum (15 NM) and maximum (60 to 70 NM) mapping ranges depend upon the 
aircraft’s height and type of terrain. To map beyond 70 NM the conical pencil beam should 
be used by selecting the \_\_\_\_\_\_\_ position; this enables the gain to be adjusted, for ground 
mapping.

Answer 11

The minimum (15 NM) and maximum (60 to 70 NM) mapping ranges depend upon the 
aircraft’s height and type of terrain. To map beyond 70 NM the conical pencil beam should 
be used by selecting the MANUAL position; this enables the gain to be adjusted, for ground 
mapping. See Figure 13.15.

Question 12

You want to map and also detect cloud over a distance of 70 - 150nm, and select the conical beam. Which function do you use?

Answer 12

MAN mode. This is used for cloud detection and mapping between about 70 and 150 NM and selects the
conical pencil shaped beam; MANUAL GAIN for signal amplification is operative with this
selection.

Question 13

You want to observe cloud formations with the conical beam, which function do you select?

Answer 13

WEA mode. this selects the conical pencil beam (Figure 13.14) and is the usual position for observing cloud
formations; MANUAL GAIN control is now INOPERATIVE. Instead a facility called Swept
Gain, Sensitive Time Control or Automatic Gain Control (AGC) is automatically available. This
system of circuits decreases the gain for echoes received from the ever decreasing ranges of
clouds. It operates up to about 25 NM and ensures that the intensity (brilliance) of display
of a particular cloud is independent of range. Thus a small cloud at 5 NM does not give an
increasingly stronger return than a larger and more dangerous cloud at 20 NM; all clouds up to
about 25 NM are thus compared on equal terms.

Question 14

You want to map terrain below at a distance less than 70nm, which function do you use?

Answer 14

MAP mode with cosecant beam selected.

Question 15

The conical pencil beam can be selected with which function?

Answer 15

MAN mode

Question 16

Will snow give a pronounced AWR return or not?

Answer 16

Will not. Snow is a very poor reflector and will mask terrain features

Question 17

In CONT mode most severe turbulence are shown -

Answer 17

as black holes

Question 18

The areas of greatest potential turbulence occur where the colour zones are -

Answer 18

closest together

Question 19

In the horizontal plane the antenna sweeps up to __° either side of the nose
though a sector of __° on each side is generally sufficient for the role of weather depiction and
navigation.

Answer 19

In the horizontal plane the antenna sweeps up to 90° either side of the nose
though a sector of 60° on each side is generally sufficient for the role of weather depiction and
navigation.