Weather Radar | Aircraft Weather Radar System

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Aircraft Weather Radar

Aircraft Weather Radar weather radar, also known as a weather surveillance radar (WSR), is a type of radar that is fitted in aircraft to identify various meteorological conditions in the atmosphere, such as locating precipitation, calculating its speed, and even estimating weather conditions such as rain, snow, and hail. The majority of weather radars used in aircraft nowadays can detect the motion of water droplets as well as the intensity of rain.

Modern Weather Radar systems provide comprehensible weather and alert displays during all phases of flight, allowing pilots to make decisions on flight paths that are most practical. Some more advanced Radar System also gradually incorporating automation into their systems to lessen the amount of involvement necessary by the pilot and the total burden of the pilot.

Types of Weather Aids

There  are  three  types  of weather  aids most commonly used in an aircraft  flight  deck. The weather aids are often referred  to  as weather radar: 

1. Actual  on-board  radar  fitted on an aircraft for detecting  and  displaying weather activity

2. Lightning Detectors

3. Satellite or other source Weather Radar information that is uploaded remotely to the aircraft from an outside source.

Onboard Weather Radar System

Weather radar systems are installed on board all types of aircraft. They work in the same way that ATC primary radar does, only the radio waves bounce off of precipitation rather than aeroplanes. Light precipitation produces a weaker return than dense precipitation. Returns are not generated by clouds. Intense or extreme precipitation or turbulence are represented in magenta. A specialised weather radar screen is found on some aircraft. The navigation systems of most modern aeroplanes include a weather radar display.

Weather Radar Operation & Frequency

The SHF range, such as 5.44 GHz or 9.375 GHz, is used in weather radar systems. A directional antenna, normally hidden under a non-metallic nose cone, transmits them forward of the aircraft. The pulses are around a microsecond long. Radar transmits Pulses of approximately 1 micro second in length. A duplexer installed in the radar transceiver switches the radar antenna to receive for about  2,500 micro seconds after a  pulse is transmitted  to receive  and process any returns. This cycle continues, and the receiver circuitry constructs a two-dimensional image of precipitation for display. The range of the radar is controlled by the gain settings. This and other modifications are made easier by using a control panel.

The pilot is concerned about severe turbulence, wind shear, and hail. While hail can be seen on weather radar, wind shear and turbulence must be determined from the movement of any recorded precipitation. If this condition happens on a weather radar system with this capability, an alarm is issued. Turbulence in dry air is undetectable. When the radar sweep contains any topographical features, ground clutter must also be reduced. This is made easier by the control panel.

Weather Radar Precautions

During the maintenance and operation of weather radar systems, the technician must take extra precautions. To allow radio signals to travel unobstructed, the radome covering the antenna must only be coated with approved paint. Grounding strips are used in many radomes to conduct lightning strikes and static away from the dome.

It is important to follow all manufacturer instructions when using the radar. High-energy radiation can cause physical injury, especially to the eyes and testes. Do not look at the antenna of a radar that is transmitting. In hangars, radar operation should be avoided unless suitable radio wave absorption material is utilised. Furthermore, radar operation should not occur while the radar is directed at a building or when refuelling is taking place. Only qualified personal should maintain and operate radar equipment.

Lightning Detectors

A second reliable method of detecting potentially severe weather is lightning detection. Lightning produces an electromagnetic signal of its own. A receiver can compute the azimuth of a lightning strike using a loop type antenna like the one used in ADF. The ADF antenna is used in some lightning detectors. The range of a lightning strike is proportional to its power. Strikes that are close to the aircraft are plotted as such.

Stormscope is a trademarked name for a type of lightning detector. There are others who operate in a similar way. With a little mark on the screen, a dedicated display shows the position of each strike within a 200-mile range. The marks may change colour over time to signify their age. Nonetheless, a cluster of lightning strikes in a narrow region signals the presence of a storm cell, which the pilot can avoid. A multipurpose navigation display can also be used to plot lightning strikes.

Satellite or other source Weather Radar (ADS-B)

In all types of aircraft, a third form of weather radar is becoming more common. Weather information can be sent to an aircraft in flight practically everywhere in the world using orbiting satellite systems and/or ground up-links, such as those mentioned with ADS-B IN. Text data and real-time radar data are included for overlay on an aircraft's navigational display (ND). Weather radar data generated remotely and supplied to the aircraft is enhanced by combining multiple radar scans from various angles as well as satellite photos.As a result, more accurate portrayals of actual weather conditions are produced. To decrease ground clutter, terrain databases have been merged. The whole range of intelligence available from the National Weather Service (NWS) and the National Oceanographic and Atmospheric Administration (NOAA) is included in the supplemental data (NOAA).

A 1090 ES or 970 UAT transceiver with corresponding antenna must be installed on board the aircraft to receive an ADS-B weather signal, as previously stated. Satellite weather services are obtained via an antenna tuned to the service's frequency. Receivers are usually placed in a remote location and connected to existing navigational and multifunction displays. Satellite weather may be available on handheld GPS systems.

Weather Radar Control Panel

Airbus a320 weather radar image

Airbus a320 weather radar control
PWS Control Panel & ND 

Weather Radar and PWS Control Panel Airbus A320

When operating/maintaining a weather radar system, always follow the manufacturer's instructions.

System  Switch

When the switch is set to ON, the weather radar is activated for display on the ND in any mode except PLAN.

WX Image Selector Switch

The WX option displays continuously updated weather radar information on the Navigation Display in a 180° rotation.

MAP - The MAP option allows you to use the radar in ground mapping mode:

Water is represented by the colour black.

The colour green represents the ground, whereas the colour amber represents cities and mountains.

WX/TURB - The WX/TURB option displays turbulence and weather in 180° increments up to 40 NM, and weather exclusively beyond 40 NM.

Tilt Selector Switch

Tilt Selector TILT - The TILT Selector adjusts the angle of the antenna in relation to the horizon. The tilt angle is shown in the lower right corner of the ND. Counterclockwise rotation commands tilt down, while clockwise rotation commands tilt up.

Gain Selector Switch

The GAIN Selector regulates the receiver's sensitivity. When set to AUTO, it adjusts the gain automatically, and when set to MAX, it adjusts the gain manually.

Windshear Switch

PWS is deactivated when the OFF option is selected.

AUTO - The AUTO option activates the PWS if the pre-configured logic is satisfies.

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