. Earth Curvature Correction
AESS applies a correction of the Earth curvature on weather information extracted from the 3D buffer. The effects of the Earth curvature are noticeable beyond 40 NM.
Note: A straight beam over a curved ground surface is equivalent to a curved beam over a plan ground surface. Refer to Figure 7-13.
The following figures illustrate the AESS corrections.
7.1.4.1.2. Automatic Mode – WXR AUTO
In automatic mode, the AESS Weather Radar displays the weather information according to the active navigation mode:
- STANDARD WXR AUTO based on FMS flight plan path and FCU altitude when the navigation mode is managed (refer to Figure 7-15),
- BASIC WXR AUTO based on flight path along FPA up to FCU altitude when the navigation mode is selected (refer to Figure 7-16),
- DEFAULT WXR AUTO based on flight path along FPA up to 60 NM when the navigation mode is manual (refer to Figure 7-17).
. The On-Path and Off-Path Weather Concept An envelope is defined along the current flight path. The envelope expands
4000 ft above and below the flight path. In addition, the lower boundary is 25 000 ft at most, and the higher boundary is 10 000 ft at least.
-The on path weather is the weather inside this envelope,
- The off path weather is the weather outside this envelope.
The STANDARD WXR AUTO mode is active when:
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The flight crew sets WXR AUTO on the SURV panel or on the MFD SURV CONTROLS page
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The FMS flight plan is available
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The flight crew sets WXR AUTO on the SURV panel or on the MFD SURV CONTROLS page
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The navigation mode is selected
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The aircraft is converging to the selected FCU altitude.
Figure 7-17: BASIC WXR AUTO
envelope in climb
envelope in descent The DEFAULT WXR AUTO mode is active when:
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The flight crew sets WXR AUTO on the SURV panel or on the MFD SURV CONTROLS page
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The FMS flight plan is not available
- No FCU altitude is selected.
. Generation of Horizontal Weather View
AESS uses the On-path and Off-path weather concept to generate the horizontal weather view on ND. The AESS displays On-path weathers with solid colors and Off-path weathers with dashed colors.
Step 1: AESS draws the envelope of the On-path weather on theaircraft flight path (see above). current
Step 2: AESS rotates the On-path weather envelope around a vertical axis to form a 3D envelope.
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