Technique
So you know nothing about radar and want to learn.
Shadows
Thunderstorms and very tall mountains cast shadows, cities do not. To look for hazardous weather, turn the tilt to display lots of ground returns and look for a shadow. If you know there isn't a tall mountain there, you have spotted a thunderstorm.
Thunderstorms and very tall mountains cast shadows, cities do not. To look for hazardous weather, turn the tilt to display lots of ground returns and look for a shadow. If you know there isn't a tall mountain there, you have spotted a thunderstorm.
Radar shadows
For this technique to work, the beam's width has to follow entirely within the structure of the storm's core area and the storm has to be deep enough to reduce the signal to a point it casts a shadow.
Radar beam must fall completely within thunderstorm
The larger the radar antenna, the larger a storm's shadow will appear, making it easier to spot. As a rule of thumb, for a 24-inch antenna, a storm will cast a shadow fifteen times the diameter of the storm's core. For example, if the storm casts a 150 nm shadow, the storm's core is likely to be around 10 nm in diameter.
Radar shadow caused by attenuatio
You should leave the antenna gain in its calibrated mode for normal operations. If you suspect a radar shadow is just below your viewing threshold, reduce the gain so that all the display's colors are reduced. If the target is a thunderstorm (and not a city) the hiding shadow may present itself.
Radar gain tip
Procedure
The radar is calibrated to consider all reflected energy in the beam at each distance and present a color based on adding the various intensities
The radar is calibrated to consider all reflected energy in the beam at each distance and present a color based on adding the various intensities
Radar tilt management
The resulting tilt angle may result in a lot of ground clutter. This clutter can be reduced by raising the tilt so the bottom of the beam is at the bottom of the bright band, the core of the storm, which is typically around 8,000 feet.
Radar tilt management
Point the beam width to just include the bottom of the thunderstorm's core:
Radar tilt management
Radar tilt management
Tilt Management Procedure
Optimum tilt angle
Weather Examples
Stratus Rain
Stratus Rain
Stratus Rain is normally no higher than 15,000 feet and can spread for hundreds of miles; it is not particularly dangerous. Airborne radar cannot differentiate between light rain and the ground when at high altitude looking down. The reflectivity of the ground, especially if it is wet, greatly exceeds the water droplets. Once the aircraft has descended and is looking up at the rain, the problem goes away.
Stratus rain
Stratus rain summary
Ordinary Thunderstorm
The highest concentration of rain and rain-covered hail is in what meteorologists call the "bright band," typically located between 8,000 and 17,000 feet. This area offers the highest reflectivity, where the most information to radar is available. The beam must be pointed into this area to properly evaluate the storm's danger.
The highest concentration of rain and rain-covered hail is in what meteorologists call the "bright band," typically located between 8,000 and 17,000 feet. This area offers the highest reflectivity, where the most information to radar is available. The beam must be pointed into this area to properly evaluate the storm's danger.
Thunderstorm
Super-cell Thunderstorm
A Super-Cell Thunderstorm is much wider than an ordinary thunderstorm and can often be identified by the radar shadow it creates. (The green arc above is ground clutter, but this ground clutter doesn't show behind the super-cell thunderstorm which obscures all radar returns from behind.)
A Super-Cell Thunderstorm is much wider than an ordinary thunderstorm and can often be identified by the radar shadow it creates. (The green arc above is ground clutter, but this ground clutter doesn't show behind the super-cell thunderstorm which obscures all radar returns from behind.)
Super-cell thunderstorm
Radar Example of Stratus Rain, Ordinary Thunderstorms, and Super-Cell
Weather target and how they are displayed
Normal Operations
Ground Operation
Be careful to avoid radiating in the direction of people or fueling operations.
The G450 radar defaults to "forced standby mode" when on the ground. Prior to takeoff, the forced standby mode can be over-ridden by pressing the STAB button four times in three seconds. The tilt should be aimed to just avoid ground clutter, typically around 8 degrees.
Initial Climb
Adjust the tilt to maximize the return from storms of interest and to minimize the ground clutter, typically around 4 degrees. Adjust the range to about 50 nm.
Cruise
Adjust the tilt to maximize the return from storms of interest and to reduce the ground clutter to the outer third of the display. This will normally be around 3 degrees around 18,000 feet and gradually decrease to about 0 degrees at 45,000 feet. Adjust the range to about 200 nm.
Descent
You may need to raise the tilt to compensate for the deck angle of the aircraft. Contrary to popular belief, there is no "auto" function on most radars, no automatic tilt compensation for aircraft pitch attitude. In the G450 Radar system, for example, the "A" denoted by tilt angles refers to "Altitude Compensated Tilt," which adjusts tilt for the selected range and aircraft altitude.
Approach and Landing
Adjust the tilt to maximize the return from storms of interest and to minimize the ground clutter; you are now looking up at potential thunderstorms. This will normally be around 9 degrees. Adjust the range to about 10 nm.
Ground Operation
Be careful to avoid radiating in the direction of people or fueling operations.
The G450 radar defaults to "forced standby mode" when on the ground. Prior to takeoff, the forced standby mode can be over-ridden by pressing the STAB button four times in three seconds. The tilt should be aimed to just avoid ground clutter, typically around 8 degrees.
Initial Climb
Adjust the tilt to maximize the return from storms of interest and to minimize the ground clutter, typically around 4 degrees. Adjust the range to about 50 nm.
Cruise
Adjust the tilt to maximize the return from storms of interest and to reduce the ground clutter to the outer third of the display. This will normally be around 3 degrees around 18,000 feet and gradually decrease to about 0 degrees at 45,000 feet. Adjust the range to about 200 nm.
Descent
You may need to raise the tilt to compensate for the deck angle of the aircraft. Contrary to popular belief, there is no "auto" function on most radars, no automatic tilt compensation for aircraft pitch attitude. In the G450 Radar system, for example, the "A" denoted by tilt angles refers to "Altitude Compensated Tilt," which adjusts tilt for the selected range and aircraft altitude.
Approach and Landing
Adjust the tilt to maximize the return from storms of interest and to minimize the ground clutter; you are now looking up at potential thunderstorms. This will normally be around 9 degrees. Adjust the range to about 10 nm.