Appendix G should not be interpreted as a restriction precluding other means of presentation that can be demonstrated to be superior.
G.3 On-Board Weather Radar Information.
G.3.1 Background.
On-board weather radar provides forward-looking weather detection, including in some cases windshear and turbulence detection.
G.3.2 Minimum Performance Standards.
The display of on-board weather radar information should be in accordance with the applicable portions of RTCA DO-220, Minimum Operational Performance Standards (MOPS) for Airborne Weather Radar with Forward-Looking Windshear Detection Capability. TSO-C63d, Airborne Weather Radar Equipment, allows exceptions to the minimum performance standards of RTCA DO-220 for Radar Equipment Class A and B.
G.3.3 Hazard Detection.
The weather display echoes from precipitation and ground returns should be clear, automatic, timely, concise, and distinct so the flightcrew can easily interpret, analyze, and avoid hazards. The radar range, elevation, and azimuth indications should provide sufficient information for flightcrews to safely avoid the hazard.
G.4 Predictive Windshear Information.
G.4.1 General.
If provided, windshear information should be clear, automatic, timely, concise, and distinct so the flightcrew can easily interpret, detect, and minimize the threat of windshear activity.
G.4.2 Presentation Methods.
When a windshear threat is detected, the corresponding display may be automatically presented or selected by the flightcrew at an appropriate range to identify the windshear activity and minimize the windshear threat to the airplane.
G.4.3 Pilot Workload.
Pilot workload necessary for the presentation of windshear information should be minimized. When the flight deck is configured for normal operating procedures, it should not take more than one action to display the windshear information.
G.4.4 Windshear Threat Symbol.
The size and location of the windshear threat symbol should allow the flightcrew to recognize the dimension of the windshear and its position. The symbol should be presented in accordance with RTCA DO-220.
G-4
Appendix G G.4.5 Relative Position to the Airplane.
The relative position and azimuth of the windshear threat with respect to the nose of the airplane should be displayed in an unambiguous manner.
G.4.6 Range.
The range selected by the flightcrew for the windshear display should allow the flightcrew to distinguish the windshear event from other information. Amber radial lines may be used to extend from the left and right radial boundaries of the icon extending to the upper edge of the display.
G.5 Safety Aspects.
G.5.1 Functional Hazard Assessment.
Both the loss of weather information and the display of misleading weather information should be addressed in the functional hazard assessment (FHA). In particular, the FHA should address failures of the display system that could result in the loss of the display and failures that could result in the presentation of misleading weather information.
G.5.2 Misleading Information.
The functional hazard assessment should address the effects of displaying misleading information. In accordance with chapter 4 of this AC, the display of misleading weather radar includes information that would lead the flightcrew to make a bad decision or introduce a potential hazard. Examples include—but are not limited to—storm cells displayed in the incorrect position, at the wrong intensity, or mis-registered in the case of a combined (e.g., fused) image.
G-5
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