1. Lecture : Secondary Surveillance Radar (SSR) & Airborne Weather Radar (AWR)

2. B) Secondary RADAR
Secondary Radar is always known as Secondary Surveillance Radar (SSR).
SSR is complement to the primary radar as it provide ATC with additional info about aircraft such as aircraft’s call sign, altitude, speed and destination.
SSR requires an aircraft to be fitted with transmitter/receiver called as transponder.
The need to be able to identify aircraft more easily and reliably led to another radar development  SSR
-Secondary Surveillance was developed in the late 1960s. It was another form of radar surveillance that receives transmission reflections every few seconds. However, these reflections provide much more data than in primary surveillance. These reflections are digitized messages that report each aircraft's identifications and altitude.
These information are transmitted back by the Aircraft’s Transponder on the 1030 MHz back to the ground SSR’s Antennae

3. Secondary Surveillance Radar (SSR).
SSR antenna mounted on top of Primary Radar

4. How Secondary Radar Works?
The ground secondary radar transmits 1030MHz signal.
The aircraft radar receives on 1030MHz and transmits back 0n 1090MHz.
The transponder reply is more powerful than the reflected radar signal allowing for far greater range. (250nm).
-Secondary Surveillance was developed in the late 1960s. It was another form of radar surveillance that receives transmission reflections every few seconds. However, these reflections provide much more data than in primary surveillance.
The transponder is a radio receiver and transmitter which receives on one frequency (1030 MHz) and transmits on another (1090 MHz).

5. Advantages of Secondary Surveillance Radar SSR
Requires much less transmitting power to provide coverage up to 200 to 250NM.
Provides more information: aircraft’s identity (its code & call sign), indicates aircraft’s altitude, speed & destination.
Can indicate if an aircraft has an emergency, has lost radio communications or is being hi-jacked.
Reply signal is much stronger as it does not rely on returning reflected signals.

6. Radar Display

8. Secondary Radar Display
What appear on secondary radar display?
Aircraft Identity.
Altitude
Speed
Direction
Example
MH092 FL280
585
Meaning: Flight Malaysian 092 cruising at 28’000ft with speed of 585knots

9. 2. Airborne Weather RADAR (AWR)

10. Introduction
Airborne Weather Radar (AWR) is used to provide the pilots about weather ahead.
The installation include weather radar antenna located in the nose of the aircraft and weather radar display inside the cockpit.
The radar information can be displayed in combination with the aircraft route on the EFIS Navigation Display (ND)
Weather radar is used for severe weather avoidance
Bands: MHz, MHz, GHz, GHz

11. The antenna is housed in a radome made of composite materials located in the nose of the aircraft.

12. How Airborne Weather Radar Works
A antenna which sweeps side to side transmits Super High Frequency (SHF) signals which is 9Ghz
When hit the reflective objects (precipitation), the signals is reflected back to the antenna receiver.
The returns (echo) are displayed to the pilot on the aircrafts radar screen.

13. Precipitation
Weather radar is function to detect, locate, and measure the amount of precipitation.
Precipitation is within or falling from cloud.
It includes rain, snow, ice & hail.
Different precipitation has different reflective levels.
A weather radar is used to
To locate precipitation
To calculate its motion,
To estimate its type (rain, snow or hail)
To forecast its future position and intensity.

14. Airborne Weather Radar Works
The goal of weather radar is to display areas of heavy precipitation, which generally indicates areas of turbulence.
Different types of precipitation have different reflective qualities.
Reflectivity of precipitation is directly related to moisture content.
Large water droplets show the strongest returns, while dry hail or snow will show light returns, or no returns at all.
Weather radar detects raindrops, not clouds or fog.

15. Airborne Weather Radar Works
The precipitation painted (depicted) by airborne weather radar is not of primary concern, however it is representative of areas of severe weather.
Areas of large raindrop size=high rainfall rate=intense storm=turbulence.
The turbulence associated with convective clouds is often severe and always dangerous.
Other dangerous factors associated with thunderstorms are: severe icing, hail, lightning, strong downdrafts.

16. Modern radar displays are full color:
Older weather radar displays depict weather in a monochromatic form. Areas of stronger returns will be brighter than weaker returns.
Modern radar displays are full color:
Level 1: light precipitation-green
Level 2: moderate precipitation- yellow
Level 3: heavy precipitation- red
Level 4: very heavy precipitation- magenta
Level 5-6: intense/extreme precipitation- may be an area of no returns (black)
Attenuation can cause shadowing to occur, displaying an area of no returns where heavy precipitation exists. An area of intense activity may cause complete attenuation resulting in no signal penetration. Modern systems have alerts which will be displayed in areas of possible shadowing.
The display will incorporate range and bearing information to aid the pilot in weather avoidance.
EFIS allows the weather information to be displayed on the pilots HSI.

17. Weather radar is painting a cell at 40NM
Weather radar is painting a cell at 40NM. But we have no idea what portion of the cell we are painting (upper, mid, lower)
3° beam width at 40NM is feet.
Adjust tilt down until we paint continuous ground returns at 40NM. Now we have established a ground base.
We know that 1° at 40NM is 4000 feet, so if we tilt up 1° we know the bottom of the beam is at 4000AGL and the top is at 16000AGL.
If we continue tilting up we can progressively scan the vertical aspect of the cell, and find the altitude of greatest intensity, as well as approximate tops (wet tops).
The most important information gained by this technique is the accurate location of storm cells, without proper tilt orientation we could mistake a strong cell for an area of light precipitation.

18. CAUTION: weather radar emits harmful radiation, it should not be operated when people are standing within 50 feet of radome or during refuelling.
The safe and effective use and interpretation of airborne weather radar comes with experience.
It is an active system: you must adjust gain, tilt, and range settings to actively scan the sky.
Keep the weather radar in standby when not in use, when needed it will be available. (some units take 3 or more minutes to warm up.)
When convective activity exists you should start using radar to scan the sky before you take off and for the duration of the flight.
Interpret the information and decide on a deviation plan before 40NM.
Continue to adjust your flight path accordingly.
As a general recommendation avoid all storms by:
5NM when flying below the freezing level
10NM when flying above the freezing level
20NM for any storm changing shape rapidly or displaying characteristics of severe weather.
NOTE: This is a generalization only, severe weather is dynamic and impossible to accurately predict. Weather avoidance is dependant on equipment quality, aircraft type, pilot experience, and specific conditions.