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					    Honeywell Inputs to the FAA Regarding the Pending Equipment TSO for
                Airborne Predictive Wind Shear Radar Systems
                                 January, 2005


Introduction:
Honeywell prepared this paper in anticipation of pending FAA actions to issue a
Technical Standard Order (TSO) for Airborne Weather Radar with Forward
Looking Wind Shear Capabilities. The FAA may opt to create a new TSO or may
opt to amend the existing Airborne Weather Radar TSO, C63c. Regardless of
which option the FAA selects, Honeywell assumes that RTCA/DO-220 (with
Change No. 1) will be cited in the TSO as the “Minimum Performance Standard”.
The following are Honeywell’s recommendations for corrections and/or additions
to the assumed “Minimum Performance Standard” as embodied in RTCA/DO-
220 (with Change No. 1).

Two change categories are delineated below. The first category contains four
recommended changes applicable only to DO-220. These changes rectify
discrepancies between DO-220 and the SRD. The second category contains
recommended changes applicable to both DO-220 and the SRD (reference 1
below). Changes to the SRD would not be required if a TSO referencing
RTCA/DO-220 existed. However until the FAA issues an official TSO the SRD
will continue to be the official FAA document delineating Predictive Wind Shear
certification requirements. Honeywell therefore recommends that the changes in
the second section be applied to both DO-220 and the SRD.

To expedite the change processes, it is recommended that any changes to the
SRD be accomplished by the FAA and a new version released. Changes to DO-
220 are another matter. DO-220 is not controlled directly by the FAA it is
controlled by RTCA. It would be incumbent on RTCA to reconvene a special
committee if any direct revisions to DO-220 are deemed to be necessary. The
FAA may request RTCA to make direct revisions to DO-220. However, they also
may choose to capture the DO-220 changes directly in the TSO as “Additions” to
the “Minimum Performance Standards” under the TSO “Applicability”. RTCA
involvement would not be needed if these changes are incorporated in the TSO.

All recommended changes herein are indicated by strikethroughs to indicate
deletions and by the use of underlines to indicate additions.

References:
   1) “Airborne Short and Long Range Windshear Predictive Systems (Forward
      Looking Windshear Systems) Interim Certification Requirements” revision
      10.2, January 1995, FAA Certification Team (Forward Looking Windshear
      Working Group involved in exemption #5256). In keeping with current FAA
      practice this document will be referred to herein as the “SRD”.
   2) RTCA/DO-220, “Minimum Operational Performance Standards for
      Airborne Weather Radar with Forward-Looking Windshear Capability”,
      September 21, 1993.
   3) RTCA/DO-220 “Change No. 1”, March 27, 1995. In keeping with current
      industry practice RTCA/DO-220 with Change No. 1 will be referred to
      herein as “DO-220”.


Recommended changes specific to DO-220:
  1) Paragraph 2.2.2.7.2.2 Must Not Alert (Nuisance).
     This paragraph should be changed as follows:
     “The windshear system must NOT issue alerts (Nuisance) on windshear
     threat when the one km (radial) averaged F factor is less than or equals to
     0.085. The probability of a nuisance warning level III alert shall be less
     than 4 x 10-3 per 1 x 10-4 or less per windshear threat event. This shall be
     determined in accordance with Appendix B D, or equivalent procedure, for
     events with reflectivity greater than 0 dBz.”
            Justification: the recommended change brings DO-220 paragraph
            2.2.2.7.2.2 into agreement with SRD paragraph 4.1.20 and corrects
            a few minor grammatical errors and an Appendix reference error.

   2) Paragraph 2.2.2.7.2.3 Missed Events.
      This paragraph should be changed as follows:
      “The probability of a missed (must alert) event shall be 10-5 of less, per
      windshear event. This shall be determined in accordance with Appendix B
      D, or equivalent procedure, for event reflectivity of 0 dBz.”
             Justification: the recommended change corrects an Appendix
             reference error.

   3) Table 2-3 Windshear Simulation Data Sets No. 7.
      The Flight Scenario Location and Airspeed entry should be changed as
      follows:
      “-3 degrees straight in approach to the east north with the microburst
      located at the middle marker ½ NM from runway threshold.”
             Justification: the change brings DO-220 Table 2-3, scenario No. 7
             into agreement with SRD Table 9, scenario No. 7.

   4) Table 2-3 Windshear Simulation Data Sets No. 6 and 7.
      The Growth stage entries for both data sets should both be changed as
      follows:
      “Develpoing Developing.”
             Justification: correct spelling typos.
Recommended changes to both DO-220 and the SRD:
  1) DO-220 Table 2-3, No. 2, 3 and 4 and SRD Table 9, No. 2, 3 and 4.
     The Flight Scenario Location and Airspeed entries for all three data sets
     should be changed as follows:
     “… located at the middle marker 1.2 ½ NM from runway threshold.”
            Justification: correct typos for scenarios No 2, 3 and 4. All other
            DO-220 Table 2-3 (and SRD Table 9) scenario requirements place
            the middle marker at ½ NM from runway threshold.

   2) DO-220 Table 2-3, No. 13 and SRD Table 9, No. 13.
      The NASA Terminal Area Simulation (TASS) Data Set entry should be
      changed as follows:
      “7/11/88 Incident Case Denver Colorado DATA SET/TIME: 349 351
      Multiple Microburst.”
             Justification: Per SRD Appendix E (and DO-220 Appendix A),
             DATA SET 349 was intended to be used only twice (for scenarios
             No. 6 and 7) while DATA SET 351 was intended to be used ten
             times (scenarios No. 8 through 17). DO-220 Appendix A specifically
             cites DATA SET 351 for the ILS Approach (Track 090) in Figure
             A.5.12 on page A-47 which corresponds to scenario No. 13.

   3) DO-220 Table 2-3, No. 17 and SRD Table 9, No. 17.
      The Flight Scenario Location and Airspeed entry should be changed as
      follows:
      “1000’ AGL level flight, standard rate turn to the right to the localizer, as
      limited by 25 degrees of bank”.
             Justification: per SRD Appendix E, page E-5, the scenario indicated
             by “Curved approach at 200 knots” for DATA SET 351 calls for “fly
             north … then turn right to intercept localizer …”

   4) DO-220 Table 2-3, No. 25 and SRD Table 9, No. 25.
      The Flight Scenario Location and Airspeed entry should be changed as
      follows:
       “1000’ AGL level flight, standard rate turn to either the left or to the right to
      the localizer, as limited by 25 degrees of bank”.
             Justification: per SRD Appendix E, page E-7 and E-8, the scenario
             indicated by “Curved approach at 200 knots” for DATA SET 540
             calls for “… a left turn or … for a right turn”.

   5) DO-220 Table 2-3, No. 27 and SRD Table 9, No. 27.
      The Flight Scenario Location and Airspeed entry should be changed as
      follows:
      “1000’ AGL level flight, standard rate turn to the right to the localizer, as
      limited by 25 degrees of bank”.
          Justification: per SRD Appendix E, page E-9, the scenario indicated
          by “Curved approach at 200 knots” for DATA SET 614 calls for “…a
          right turn…”

6) DO-220 Table 2-3 and SRD Table 9.
   One scenario associated with TASS DATA SET/TIME 614 is missing from
   both tables. Both tables should be changed as follows:
   Scenario No. is TBD (Honeywell suggests No. 29.1). All table entries for
   the missing scenario should be identical to the entries for scenario No. 29
   except “Approx. peak 1 km FBAR” which should read: 0.10 and “Flight
   Scenario Location and Airspeed”, which should read: -3 degree straight in
   approach to the east with a 90 degree heading. The microburst is located
   at the middle marker ½ NM from the runway threshold.
          Justification: per SRD Appendix E, page E-9 and E-10, DATA SET
          614 was intended to be used for seven different ILS approaches,
          including one approach on Track 090. Also DO-220 Appendix A
          specifically cites DATA SET 614 for the ILS Approach (Track 090)
          in Figure A.50.30 on page A-56 which corresponds to the missing
          scenario. This figure indicates a peak FBAR of 0.10. In addition, the
          remaining six out seven ILS approach tracks listed on SRD pages
          E-9 and E-10 are correctly instantiated in SRD Table 9, and DO-
          220 Table 2-3, beginning with No. 28 and ending with No. 33. This
          scenario omission appears to be the result of an oversight in the
          preparation of SRD Table 9 which subsequently propagated into
          DO-220 Table 2-3.

				
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