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Weather Radar – With Turbulence Detection and PWS

Weather Radar – With Turbulence Detection and PWS. Some comments on the proposed Appendix D to TSO c63c By Jon Hildrum. Weather Radar – With Turbulence Detection and PWS. General.

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Weather Radar – With Turbulence Detection and PWS

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  1. Weather Radar – With Turbulence Detection and PWS Some comments on the proposed Appendix D to TSO c63c By Jon Hildrum

  2. Weather Radar – With Turbulence Detection and PWS General • There is a proposal to revise TSO c63c to include requirements for Predictive Windshear (PWS) and Turbulence as part of the TSO. • A draft of Appendix D was provided for review • The following represents some comments to the draft for consideration by the group.

  3. Weather Radar – With Turbulence Detection and PWS • Ground rules and Assumptions • These Comments applies to a Weather Radar System including Predictive Windshear function and enhanced turbulence. • The PWS requirements would not be applicable to a Weather radar system not including PWS. • The Enhanced Turbulence Display is advisory only. As such it is treated as an improvement to the basic Weather radar function. There is no new functionality added as a result of enhanced turbulence. It is a minor change to the existing wxr.

  4. Weather Radar – With Turbulence Detection and PWS General Comments • Use DO-220 as a requirements document. It provides requirements for the Predictive Windshear function. It also enhances some of the requirements applied to a weather radar system above and beyond those found in D0-173. • DO-220 includes environmental qualification requirements (DO-160C). I would like to suggest that DO-160D or later be included. • The Radome shall comply with DO-213 class C or better for systems including PWS. A lower class radome is acceptable for Weather only system. • A suggested change from DO-220 is to make the advisory alert for PWS optional. • Section 3 and 4 of DO-220 are too demanding

  5. Weather Radar – With Turbulence Detection and PWS Specific comments • Integrity requirements • There are no specific requirements for Weather Radar. • The Requirements for Windshear function varies from none for availability to 10-5 for missed alerts and un-annunciated failure. This makes the windshear function Major (per AC 25.1309) • JAA has insisted on applying AC 25-11 to the weather Radar. “ Display of Weather in the cockpit is a nonessential function ; however, presentation of hazardously misleading information must be improbable”

  6. Weather Radar – With Turbulence Detection and PWS Specific comments • Integrity requirements - conclusion • The Weather Radar needs to be treated as a Major function. • DO-178B level C or better for software • Failure analysis for Major functions • Analysis to show hazardously misleading information

  7. Weather Radar – With Turbulence Detection and PWS Integrity Requirements

  8. Weather Radar – With Turbulence Detection and PWS Specific comments • Accuracy requirements: • D0-220 and AC25-7a defines accuracy requirements for range and bearing. These looks ok • Antenna stabilization is different in DO-220 and ARINC 708(). The DO-220 requirements are too loose. My suggestion would be ¼ degree static and ½ dynamic • Transmission losses (Waveguide and Radome losses shall be less than 4dB. This is not well defined and different revisions of ARINC 708() used different values

  9. Weather Radar – With Turbulence Detection and PWS Specific comments • Radiation Hazards • Suppliers shall provide any restriction necessary for their equipment. • Suggested Standards to use: o 47 CFR 1.1310 Radio Frequency Radiation Exposure Limits (FCC) o American National Standards Institute (ANSI/IEEE) c95.1-1999 o International Commission on non-Ionizing Radiation protection (INCIRP) “Guidelines for limiting exposure to Time-varying Electric, Magnetic and electromagnetic Fields (Up to 300GHz) • Note: AC 20-68B is a little out of date.

  10. Weather Radar – With Turbulence Detection and PWS

  11. Weather Radar – With Turbulence Detection and PWS Some Applicable Regulations

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