WEATHER RADAR Flashcards
What are the advantages & disadvantages of AWRs at higher frequencies?
Advantages:
- Improved reflectivity
- Better detection
- Better resolution
Disadvantage: Increased attenuation
- Range attenuation
- Precipitation attenuation
What is the normal altitude range & temperature of the icing level?
15000 - 23000ft with a temperature betwwen 0 and -15 deg C
What is considered to be a good radar target?
Surface to 15000 ft section gets all the moisture in a liquid state, it is a good radar target.
Tilting up when scanning a cell, the return will weaken as the water becomes
Ice and less reflective
Does the threat diminish above the -15 deg level?
No
What is overscanning?
Directing the beam too high
Which sections of a storm should one aim at to find the best return?
Bottom two sections
Which one is right in the following sentence ?
The closer to a storm, the LESS/MORE the attenuation
Less
What effect does rain have on precipitation attenuation?
Rain prevents depth detection and secondary target detection
Azimuth resolution, when is it not possible for the WX radar to distinguish between two targets?
When both targets are at the same range and less than a beam width away in azimuth they will appear as a solid band of weather across track. As the cell get closer they will split into 2 separate returns.
Range resolution, how long are the pulses at high & low display range?
- High range: 1.5NM
- Low range: 1NM
It means that 2 targets separated by less than these distances will be detected as 1 single return.
Is continuous use of manual gain recommended?
No, since the radar colour presentation is not calibrated in manual gain.
Which of the display level colours is not affected by the position of the gain control?
Magenta
When WX/TURB is selected, magenta indicates MOD to SEVERE turbulence within _____
40 NMs
Which radar return shapes may indicate severe turbulence and hail?
Fingers, hooks, scalloped edges, horseshoe and fig 6 shapes
What is the main difference between Ground and Weather return if the tilt is adjusted upwards?
WX returns will initially remain unchanged unlike other returns
Which of the following, cast radar shadows: cities, thunderstorms, mountains
Thunderstorms & mountains
What does the WX radar use to detect windshear or microburst?
Doppler frequency shift (raindrops moving towards the radar at one range and away at a slightly different range)
Can CAT be detected?
No, due to lack of reflective precipitation
When is turbulence mode recommended?
Assessing or avoiding convective wx
When assessing wx, what should be done to avoid being boxed in?
Select longer ranges
Which side of a thunderstorm is turbulence usually more intense?
Downwind
A thunderstorm usually moves in the direction of _________
The mean wind between 5000 and 30000 ft
What should be kept in mind when dimming lights in the flight deck at night?
Temporary blindness from lightning flashes
When do you need to establish a protection zone?
In IMC or at night:
- On departure when passing 20000 ft
- In Cruise after a significant heading change
In IMC or at night, the range/tilt displayed should initially be ___/____
40 NMs / -10 deg
The radar scans side to side in ________
4 seconds
When should the range be set to 80 NMs?
When the ground stripe is at the outer edge of 40 NMs
The screen should never be just ______
Black
Take avoidance action before the target is inside the ______ range
40 NM
A storm should be avoided by at least ______ while two storms should be separated by _____to fly between them
20 NMS. 40 NMs
Thunderstorms can be avoided vertically.
No
If within 40 NMs, all cells should be avoided by ______
20 NMs
If downwind of a storm, what is the rule of thumb to calculate the range of turbulence
1 NM for each 1 Kt of wind at current FL
In IMC or at night, at least one ND should have a range displayed of _____
80 NMs max 160 Nms
Tilt setting for T/O
+4 Deg
The tilt setting from initial climb to 20000 ft should be _______
+2 to +3 deg
If a course change of _____is made, the protection zone should be re-established
45 deg
Why is it advisable to keep the ground returns at 80 Nms?
To point the beam into the reflective part of the cloud
During descent tilt may be increased below_______
15000 ft
In the final stages of the approach, tilt range should be ______
+2 to +4 deg
Which common error results in damage or injury?
Overscanning
What type of conditions offer the best reflectivity and weather echo return?
Ground Clutter, Wet Hail, Rain, Wet Snow, Dry Hail, Dry Snow, Drizzle
What is the definition of tilt?
Tilt is the angle betwwen the antenna and the horizon.
It is independent from aircraft pitch and bank angle.
What are the 3 sections of a Storm cell?
Upper level: moisture in dry frozen state
Icing level: can be the most reflective area
Lower level: moisture in a liquid state
How do you establish a protection zone?
Start with the Range at 40NM, tilt down at least -10
Tilt up slowly to bring the stripe at the outer edge
Select Range 80NM and tilt up slowly
Leave the tilt with the return at the outer edge
