The flight crew uses four features to operate the radar:
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Antenna tilt: this is the angle between the centre of the beam and the horizon
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Range control of the ND: this has an essential influence on the optimum tilt setting.
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Gain control: this adjusts the sensitivity of the receiver.
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Radar modes: weather (WX) or weather + turbulence (WX + T).
Early generation of full manual controlled radars were without auto tilt.
Honeywell introduced the first weather radar featuring with an automatic tilt computation named “Autotilt”.
When in Autotilt mode, the radar uses the EGPWS terrain database and automatically adjusts the antenna tilt based on the aircraft position, altitude, and the selected ND range (fig.6).
The next generation of radars (fully automatic radars) optimize weather detection and decrease significantly the pilots’ workload necessary to understand the complete picture of the weather ahead. They included automatic functions, which:
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Scan airspace ahead of the aircraft with multiple beams
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Feature a three dimensional (3D) buffer to store weather data
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Automatically compute and adjust the antenna tilt
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Offer independent pilot control and display selection.
This kind of radars automatically adjusts the gain and tilt based on various parameters (aircraft altitude, geographical area, season, time of the day) to obtain the best weather display in each geographic region.
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