RTCA SC-230 Meeting Minutes (June 25-27, 2019) · RTCA Paper No. 193-19/SC230-040 July 31, 2019 RTCA, Inc. 1150 18th Street, NW, Suite 910 Washington, DC 20036 Phone: (202) 833-9339

RTCA Paper No. 193-19/SC230-040

July 31, 2019

RTCA, Inc. 1150 18th Street, NW, Suite 910

Washington, DC 20036 Phone: (202) 833-9339

Fax: (202) 833-9434 www.rtca.org

RTCA SC-230 Meeting Minutes (June 25-27, 2019) Attendance list:

June 25th - WG10 Name Company Karan Hofmann RTCA Lee Nguyen FAA Tom Bond FAA Chris Dumont FAA Stephanie DiVito FAA Thibault Lefez Airbus Luke Tschacher Boeing Kenny Ren Boeing Melissa Bravin Boeing Dawn Gidner Honeywell Jan Lukáš Honeywell Marius Irimia Collins Mark Smith Collins Venkata Sishtla Collins Jeff Finley Collins Steven Harrah NASA Tom Ratvasky NASA Fred Proctor NASA Ivan Clark NASA Patricia Hunt NASA Justin Strickland NASA Dan Stechman OU Rockee Zhang OU Shigeru Machida JAXA

June 26th - WG11 Name Company Lee Nguyen FAA Tom Bond FAA Chris Dumont FAA Stephanie DiVito FAA Thibault Lefez Airbus Kenny Ren Boeing Dawn Gidner Honeywell Jan Lukáš Honeywell Jeff Finley Collins Venkata Sishtla Collins Marius Irimia Collins Steven Harrah NASA Tom Ratvasky NASA Fred Proctor NASA Ivan Clark NASA Patricia Hunt NASA Justin Strickland NASA Shigeru Machida JAXA Hamaki Inokuchi JAXA Nobuki Kotake JAXA Masatoshi Abe MELCO Shumpei Kameyama MELCO Bob Avjian MITRE Rockee Zhang OU Dan Stechman OU

June 27th – WG10 Name Company Lee Nguyen FAA Chris Dumont FAA Stephanie DiVito FAA Thibault Lefez Airbus Kenny Ren Boeing Dawn Gidner Honeywell Jan Lukáš Honeywell Marius Irimia Collins Mark Smith Collins Venkata Sishtla Collins Jeff Finley Collins Steven Harrah NASA Tom Ratvasky NASA Fred Proctor NASA Ivan Clark NASA Patricia Hunt NASA Justin Strickland NASA Dan Stechman OU Rockee Zhang OU Shigeru Machida JAXA Bob Avjian MITRE


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June 25, 2019 (9:00-17:00 EDT) Administrative and agenda review: Welcome/Administrative Remarks/Recognitions - Provided by Karan Hofmann from RTCA. Introductions/Agenda/Minutes Approval - Minutes were approved without comment. Review WG-10 Schedule and Deliverables - Presented by Jeff within the agenda presentation which will be posted on the RTCA workspace. Detailed WG-10 Agenda presented by Thibault: Day 1: WG10 - HAIC:

1) WG-10 – Context and Schedule Reminder – Co-Chairman – Thibault Lefez (AIRBUS) 2) Action Review (if any) – Secretary 3) Operational Concept presentations

a. OEMs presentations (AIRBUS, BOEING, EMBRAER, …) 4) Status on HAIC threshold definition

a. OEMs presentation on existing events and recommendations b. NASA status

5) Threshold acceptability and way forward – Co-Chairman – Thibault Lefez (AIRBUS) 6) V&V methodology proposition – Co-Chairman 0 Steven Harrah (NASA) 7) Models Discussions – Co-Chairman – Steven Harrah (NASA) 8) Pre-MOPS document status and open comments review 9) HAIC document format discussion 10) Meeting Wrap-up 11) Next plenary meeting organization – Co-Chairmen

Group reviewed Preliminary HAIC document Format and Requirements The group discussed SC-230 WG10 deliverable and all agreed that the updated RTCA DO-220B will be produced based on the current DO-220A Change 1. Within the proposed RTCA DO-220B document, group members had discussions regarding whether or not to include the detailed NASA SWERLing algorithm. Radar manufacturers prefer not to specifically call out the algorithm to allow for the possibility of using custom algorithms from different vendors (similar to Predictive Windshear descriptions); FAA desires the inclusion of the algorithm at least as a reference (similar to TCAS and TAWS MOPS’s).


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Thibault presented AIRBUS view for Operational concept. Group had discussion on Moderate Ice Crystal concentration being “situational awareness” vs “alert”. The 1 vs 3g/m3 thresholds could potentially be altered based on more information available from Engine manufacturers. On Slide 7 of the presentation, there were some clarification needed for the reference to “Accuracy”, which is intended to mean “Range Accuracy”. Minimum range and max range still need to be defined based on needs from Engine and probe manufacturers. Due to the existence of many industry groups studying HAIC, group proposed to review EIWG deliverable. FAA has strong needs for Weather radar to detect HAIC to both characterize and identify HIAC areas. FAA regards WXR as tactical avoidance for HAIC although airlines may use it as a situational awareness tool depending on each airline’s operational guidance. Status on HAIC threshold definition: [Action-Kenny/Thibault] contact Business and Regional OEMs for participation, Tom confirmed there were cases of Engine flameout for the regional aircraft (specifically noted an event related to Beech) and define requirements for smaller diameter radar antennas. [Action-OEM] Address open questions for HIWC performance requirements: Discussion with Mellissa Bravin (Boeing EIWG rep) 13:00 EDT:

1. Threshold a. 1g/m3 vs 3g/m3 are the currently defined thresholds for moderate and severe; however,

the industry do not have that much in-situ data to support the threshold. TWC models are being constructed, expect to be available in 9-12 months

b. New engines are more susceptible during cruise altitude c. Older engines are more susceptible during descend phase.

2. Duration: according to Boeing Engine icing Database, average exposure duration is about 100 NM of High Ice Water Content to observe engine flame out event

a. Potentially, exposure duration (traverse/flight plan) can be used to determine whether it is an alert [Action-Kenny]: routine follow-up with Melissa Bravin for updated status regarding engine manufacturer needs and operational needs

3. Range a. Desire 80 NM detection in order to perform operational avoidance

4. Avoidance vs Situational Awareness


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a. Avoidance is desired for significant presence of icing along flight path ahead b. Radar Manufacturers proposed additional criterions for distinguishing HAIC awareness

vs avoidance. In addition to the HAIC Concentration thresholds (1 vs 3g/m3). c. The definition of significance can be dependent on the duration of icing that can be

endured by Engine and Probe before failures occur. i. [Action-Kenny] Boeing to look for Airdata probe database

d. [discussion] If it is determined based on duration of encounter that it is awareness only, the range of detection can be only (for example 10/12 NM), but if it is determined that a long encounter is expected and avoidance is needed, then the range is at least 80 NM.

5. Current Operational Remedy a. Avoidance, avoid laterally b. From engines side, detection distance of at least 80 NM is needed to be operationally

significant. (inform ATC, and perform maneuver) c. Current operational procedure is pilot & FO select 80NM & 160 NM, with down tilt,

identify threat area (Amber & Red) and perform lateral avoidance. In order to get a better understanding on the threshold and range needed for HAIC avoidance and awareness functions, the group suggested to get in contact with other industry groups who are also studying HAIC, the list discussed is provided below: [Action] Need to tie the thresholds back into other groups:

1. [Kenny/Tom] ARAC, ICI working group: engine mfrs, AC mfrs, probe mfrs, regulators, research orgs. Tasked to assess flight test data against appendix D.

2. [Kenny] EIWG. 3. [Kenny] ICC- Ice Crystal Consortium: industry only group 4. EUROCAE WG89 – probe, pitot static manufacturers, regulators, AC mfrs, updated SAE

standards. Updated SAE paper AS5562. 5. EUROCAE WG95 – aircraft icing detection [Action: to revisit the published document] 6. BRJ contacts:

a. Tom Dwier from Textron (Cessna side) is on ARAC Ice Crystal Icing working group. Also on WG89. [email protected]

b. Christopher Baczynski from Mitsubishi MITAC is also on ARAC Ice Crystal Icing working group. [email protected]

NASA presentations: Steve presents NASA SWERling algorithm updates.

1. SWERLing technique seems to work consistently and holds to a good range (60NM was used during NASA flight test campaign due to hardware setup used during flight test)

2. The technique can potentially provide guidance on vertical maneuver with the added radar information to escape the HIWC region.

3. [cross reference] to day 3 presentation on NASA Numerical Icing Model development, The radar return with SWERLing algorithm seem to agree well with the numerical simulation visually


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Justin presents: Radar detection of high concentrations of ice particles (probabilistic performance assessment)

1. The data analysis reveals that the HAIC moderate/severe thresholds do not necessarily have to be fixed, instead, they may be temperature dependent to better meet the nuisance requirements set forth in the feasibility study.

2. Jeff proposed to explore the use of a low pass filter approach to the data analysis in addition to point to point comparison (zoomed time scale plot data)

Lee Nguyen from FAA briefly brought up the topic of the additional ADS-B OUT weather related squitters as a part of the DO-260C update, SC-230 WG-10 was asked to provide any recommendations from the weather radar side. The additional information include Air to air, air to ground, wake turbulence, weather forecasting for separation management, and the squitters will need to be incorporated within a year. To populate the reserved registers (~55 bits), aircraft config, aircraft l/w, aircraft icing, wind, etc.


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June 26, 2019 (9:00-17:00 EDT)

Administrative and agenda review: Introductions/Agenda - Provided by Jeff on behalf of Karan from RTCA. Review WG-11 Schedule and Deliverables - Shared by Jeff and captured in the agenda to be posted on the RTCA workspace. Schedule: Day 2: WG-11 Lidar:

1) Action Review (if any) – Secretary 2) Past Accomplishments on Airborne CAT Sensing LiDAR – NASA 3) Schedule Discussion – Shumpei/Venkata 4) Presentation of Atmospheric Modeling Study and its Conclusion

a. MELCO b. NASA

5) Feasibility Report Progress a. Airframe Requirements – OEMs b. LiDAR Compliance with OEM Goals – MELCO, Others? c. V&V, HMI - Venkata

6) Next Steps 7) Action Item Review and Wrap-up

Status: Fred Proctor from NASA has decided to retire, but he will be available to the SC-230 group as a Distinguished Researcher Ivan (NASA) presents past accomplishments on airborne CAT sensing LiDAR: [Action Ivan] upload presentation material to RTCA WG-11 workspace NASA first reviewed material information comprised mostly of aviation safety program from 1999-2004. During the aviation safety program Lidar testing, several Lidar designs were examined for both windshear detection as well as CAT detection. In addition, the advantages and disadvantages were highlighted for each design. Several highlights of accomplishments and observations are listed below:

• Aviation Safety Program demonstrated 2um lidar is capable of detecting CAT. NASA successfully collected backscatter data at cruise level.

• Light frosting does not seem to adversely affect the Lidar performance.


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• Windshear detection lidar mounted on NASA B737, could not compete with Radar at the time due to EMI and mounting issues.

• Due to installation resource limitation, the demonstrated Lidar system was not optimized for weight and size.

In addition to sharing info on the Lidar designs tested during the aviation safety program, NASA also presented several recent design Lidar designs which are more compact, though intended for shorter range applications (refer to presentation material for all details):

• SBUR/STTR is a small form factor wind measurement device suitable for urban air mobility and drones. FAA expressed some interest in this technology as a wake detecting device.

• Current project: compact high power 3D Lidar system for UAS, this was presented to SC-228 UAS Open items/issues/Current status: NASA also highlighted several areas of needs:

• Flight hours at cruise altitudes o Identified as a major gap o Measuring turbulence levels requires a large number of flight hours

• Flight hours in moderate or stronger turbulence o Mid-level altitudes with focus on convective (storm) and breaking wave turbulence o Performance envelope for onboard radar and lidar

• Extended datasets for aerosol/turbulence correlation modeling • Scanning versus single line of sight configuration

o Scanning will enable better characterization of turbulent events More direct comparison with radar for joint tests

o Include a mixture of both modes Ivan from NASA has also indicated that Phil Gatt from Lockheed was also a key participant in the NASA Lidar testing campaign, [Action Ivan] to invite Phil Gatt (Lockheed) to join the group WG-11 group inquired NASA to share any experiences in the likely location/condition to find Clear Air Turbulence events. NASA briefly described CAT occurrence could be “forecasted” using: NCAR turbulence forecast, shape of Jetstream, if there are strong set of kinks, look at NCAR forecast to the east and those are more likely to result in CAT. After NASA’s Lidar presentation, Jeff had several follow on questions:

1. Eye safety: It’s mostly a none-issue for personal inside the cabin due to shielding properties of windows and metal. For ground personal, the exposure is going to be very brief. Ivan provided industry guidance documents on Laser Eye-safety:


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AS6029A: SAE-AERO: Performance Criteria for Laser Control Measures Used for Aviation Safety AC70-1: OUTDOOR LASER OPERATIONS

2. Coupled flight control Turb mitigation techniques:

[action Kenny] Chris Borland from Boeing conducted analysis on the parameters needed by the Flight Controls to perform feedforward turbulence mitigation, the analysis was done as a part of NASA contract. Chris has been long retired, need to find new contact on this subject matter. LiDAR is more intended to be a coupled flight controls sensor rather than an avoidance system due to range limitations.

3. Reliability of LIDAR system:

Since Airborne Lidar has not been used extensively, the only real world reliability data available to be used as reference will be automotive lidars. The automobile lidars can potentially provide wind sensing capability of about 50 meters.

Shumpei reviewed schedule Section 5, realistic performance, will be the important subject for this meeting. First draft review available October (tentative). Final review and comments will be held during January plenary, March plenary will be used to resolve the comments. Editorials to follow. Feasibility report submittal around May time frame. September/November may also be opportunities for another 2 plenary meetings. [Action Ven] update schedule according to discussion to include the upcoming plenary activities. FAA comments/proposals regarding deliverables and activities after FS FAA proposed, after FS release, TOR can be updated to include MOPS development for CAT. Committee should also consider installation guidance. The information will be included in an AC. MOPS will be for lidar manufacturers to obtain TSO. [Action (not immediate) – To be decided when approaching MOPS development] Review installation guidance from SC-220 to develop a similar guidance for Lidar, FAA may consider invoking the guidance to be a part of the AC (likely a one page AC directing to the installation guidance). OEMs to identify potential installation location. [SC-220 example was sent by Lee to Kenny] [Action-HAIC (not immediate)] AC 20-182B draft will need to be updated to reflect the icing updates. The approach to updating the AC will need to be further discussed due to FAA’s current slow review progress. If the process keeps to be slow, committee may want to approach the update by including an installation guide.


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Shumpei presents modeling methods and atmospheric parameters progress. The following atmospheric parameters table was collaboratively generated by Lidar Manufacturers:

Leading into V&V, SNR will need to be measured in addition to calculated. For turbulence, group will use homogenous/isotropic parameters for calculations. Wing-loading On the topic of Lidar’s measurement of Turbulence, the group recommends following the previous works and techniques performed for Weather Radar turbulence measurements. To help Lidar manufactures with turbulence measurement techniques used by radar, lidar manufacturer needs:

1. The relationship between Turbulence and wing-loading. (Wing-loading vs spectral width of Doppler shift)

a. Weather radar already has spectral width already available which can be referenced for Lidar


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b. [Action-Lidar/WXR MFRs] to verify the equivalence between LIDAR and WXR, to compare spectralwidth, in hopes that wingloading calculations can be shared.

[Action – LIDAR mfrs] Fred needs clarification on the meteorological model requirements:

1. What grid size will be needed (model used for WXR Turb was ~25 meters), a. There are also Grid compensation done for the smaller class of aircrafts.

[Action – Jeff] find research paper on grid compensation. 2. What variations of models will be needed (different convectives / different levels of

turbulence, etc?). If resources available to collect meteorological parameters around CAT, it can be integrated with Fred’s wind field model to validate the model for MOPS development, although this is beyond scope of the FS. (Recommendation already available in the FS V&V section). Feasibility report progress update OEM presentation of FS section 4 The group jointly walked through section 4 of the feasibility report and made the following updates:

In Section 4.1.2, a note is added to potentially further define operating envelope

Section 4.1.5 was added to define Non-interference and FCC regulatory considerations

In, Section 4.5, AC voltage frequency and phase information

Consider moving “Inputs from Japanese airlines” section to appendix and summarize.

Shumpei presents FS section 5: Airbus A340 AWIATOR lidar was an attempt to demonstrate a coupled CAT detection lidar with flight controls. Summary of what has been accomplished vs not JAXA Lidar specification: 83.7kg Small LiDAR can get as small as 2lbs, short range (50 meters or so) Refer to Appendix B-23 for more examples of performance parameters of different Lidars. Current Lidars cannot satisfy OEM’s requirements, however the tradeoffs can be explored.


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[Action OEM] OEMs to consider MTBF requirements and some other physical (power, weight, volume), and environmental categories. Ven presents V&V approaches: NASA has a ported version of ADWRS (Weather Radar simulator) that’s used for testing LiDAR on ground. In order for the model to be effective, the bin width has to be small and dense. Decision is needed as to whether the model used to verify LiDAR function also needs to be certified. The current ported version used by NASA is not as generalized for use on wind field simulation, rather it’s more tailored towards wake type of CAT. [Action] –LiDAR MFRs will need to work with NASA to come up with a simulation input to be used, discuss the validity of a statistical model. [Action Ivan] mountain rotor flight data in Colorado may be available from NCAR In validation slide, actual “Weather” should be worded as “atmospheric conditions”


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June 27, 2019 (9:00-12:00 EDT)

Administrative and agenda review: Introductions/Agenda - Provided by Jeff on behalf of Karan from RTCA. Agenda item: V&V and modeling

8) V&V methodology proposition – Co-Chairman 0 Steven Harrah (NASA) 9) Models Discussions – Co-Chairman – Steven Harrah (NASA) 10) Pre-MOPS document status and open comments review 11) HAIC document format discussion 12) Meeting Wrap-up 13) Next plenary meeting organization – Co-Chairmen

Steve presents V&V methodology: Steve pointed out that ADWRS method has been successfully used in the past to perform V&V on windshear/turb. Propose HIWC Change to Database and modify ADWRS. Current ADWRS will be modified to consume NASA’s new icing model. Fred proses to model the storms with ice water content, from the IWC amount, ADWRS Pulse to Pulse reflective (amplitude) value variability is great (30db) in real measurements, ADWRS currently does not contain the variability, and hence the ADWRS will need to be modified to contain the variability. The physics of ice crystals still need to be further understood. Potentially a NASA action to perform further literature search on Scintillation process of ice crystals. Current observation presents the fact that the ICI conditions do not associate with high levels of broadening of spectral width (Doppler shift due to turb), rather high levels of “time-modulated” amplitude (reflectivity) variations are observed. [Action Steve] Retrieve Steve’s presentation material on the ADWRS change proposal. [Action] to better model the icing phenomenon and understand the physics more. [Note] The NASA icing TASS model will also include vertical profile of cloud. [Action/Pathforward] modify the ADWRS/supplier models with the current understanding and continue to validate the model.


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Fred presents Numerical Simulations – AIAA Paper 2019-3304 presentation [Action] Fred to upload deck

The path length for the tropical storms can affect engine a lot.

Surprising that the max path duration is higher in a tropical storm than it is for a major hurricane.


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[Question] does commercial aircraft fly over tropical storms? Test case? From presentation, it seems TASS model is sufficient for ICI modeling. Need to identify output (3D IWC, reflectivity, v field, turb etc) that should feed into ADWRS. [Action - group] for WG10 members to re-think about must detect/must not detect. Should be discussed in the following WG meetings (eg, storm width, high ref+high IWC, low ref+low IWC, etc), classification, and identification of test cases and how many of each scenarios are needed

[request] to further validate SWIRLing technique:

1. Find counter examples where the technique doesn’t work. a. Steve has plan to share FAA communication that will capture successes and

shortcomings of the SWIRLing technique. Thibault discusses document format and Pre-MOPS document: DO-220B will be issued to incorporate the HAIC requirements DO-220B will not be updated at this time due to the maturity of the requirements, instead all the contents will still be kept in the pre-MOPS document. Thibault discusses the pre-MOPS document. Comments are to be recorded in comments spreadsheet on the RTCA Workspace. Review Action Items Action items were reviewed with the team and are provided below. Time and Location Suggestions for Next Plenary Face to Face plenary is needed for LiDAR Feasibility FRAC resolution in March 2020. Note: most of the work will be done in the November Plenary, plan to send out a draft several weeks prior to November Plenary to gather comments and discuss during the Face to Face. [Action Jeff] to solicit location for November Plenary (OU, Toulouse, DC?) November 12-14, @ OU Telecon plenary in Sepetember is planned for September 24/25.


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Action Item # Action Person(s)

Estimated Completion

Date Day 1 WG-10 – HAIC

1

Contact Business and Regional OEMs for participation, Tom confirmed there were cases of Engine flameout for the regional aircraft (specifically noted an event related to Beech) and define requirements for smaller diameter radar antennas.

Kenny / Thibault

next WG Meeting

2 Address open questions for HIWC performance requirements

Kenny / Thibault

next WG Meeting

3 look for availability of airdata probe icing event database Kenny/Thibault next WG Meeting

4 routine follow-up with Melissa Bravin for updated status regarding engine manufacturer needs and operational needs

Kenny next WG Meeting

5 Tie the HAIC thresholds back into other groups Group next WG Meeting

5.1 ARAC, ICI working group: engine mfrs, AC mfrs, probe mfrs, regulators, research orgs. Tasked to assess flight test data against appendix D.

Kenny/Tom next WG Meeting

5.2 EIWG, ICC- Ice Crystal Consortium: industry only group Kenny next WG Meeting

5.3 Revisit EUROCAE WG95 document Group next WG Meeting

Day 2 WG-11 – LIDAR

1 Upload history of past and future NASA Lidar campaigns presentation material to WG-11 RTCA Workspace Ivan next WG

Meeting

2 Invite Phil Gatt from Lockheed to join WG-11 Ivan next WG Meeting

3 Find past work performed on coupled flight controls analysis by Boeing as a part of NASA contract Kenny next WG

Meeting

4 Update WG11 schedule according to discussion to include the upcoming plenary activities. Venkata next WG

Meeting

5

Review installation guidance from SC-220 to develop a similar guidance for Lidar and HAIC, FAA may consider invoking the guidance to be a part of the AC (likely a one page AC directing to the installation guidance). OEMs to identify potential installation location.

WG-10/WG-11 Fugure/Watch item


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6 Verify the equivalence between LIDAR and WXR, to compare spectralwidth, in hopes that wingloading calculations can be shared.

Lidar/WXR Mfrs

next WG Meeting

7 Provide additional clarification son meteorological model requirements to NASA (Fred) Lidar Mfrs next WG

Meeting

8 find research paper on grid compensation Jeff next WG Meeting

9 consider MTBF requirements and some other physical (power, weight, volume), and environmental categories

Kenny / Thibault

next WG Meeting

10 work with NASA to come up with a simulation input to be used, discuss the validity of a statistical model Lidar Mfrs next WG

Meeting

11 Provide mountain rotor flight data in Colorado may be available from NCAR if available Ivan next WG

Meeting Day 3 WG-10 – HAIC

1 Provide ADWRS change proposal write-up Steve next WG Meeting

2 Better model the icing phenomenon and understand the physics more. NASA / WG10 next WG

Meeting

3 modify the ADWRS/supplier models with the current understanding and continue to validate the model

NASA/Radar Mfrs

next WG Meeting

4

WG10 members to re-think about must detect/must not detect. Should be discussed in the following WG meetings (eg, storm width, high ref+high IWC, low ref+low IWC, etc), classification, and identification of test cases and how many of each scenarios are needed

WG-10 group next WG Meeting

5 Decide location for November plenary Jeff complete

Documents

RTCA SC-230 Meeting Minutes (June 25-27, 2019) · RTCA Paper No. 193-19/SC230-040 July 31, 2019 RTCA, Inc. 1150 18th Street, NW, Suite 910 Washington, DC 20036 Phone: (202) 833-9339