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International Civil Aviation Organization




Paris, France, 26 to 29 September 2006

Agenda Item


Operation of the WAFS


WAFS management report

(Presented by the United Kingdom and the United States)


This paper provides the management report from the London and Washington World Area Forecast Centres for the period of March 2005 through July 2006.


    1. At the first meeting of the World Area Forecast System Operations Groups (WAFSOSG/1) it was agreed that the World Area Forecast Centres (WAFC) would provide a management report at each subsequent meeting. Specifically, Conclusion 1/3 invited the two WAFC to submit a joint report that summarizes the operations, including the International Satellite Communication Systems and the Satellite Distribution Systems (SADIS). The report is to also provide information on any recent developments or difficulties encountered during the period and identify future plans for operational updates.

  2. SUMMARY OF the 2005-06 management REPORT

    1. The following highlights the main developments of the management report for the period of March 2005 through July 2006:

  1. the WAFCs removed the WAFS wind and temperature charts in T4 format from the WAFS broadcasts on 1 July 2005;

  2. the WAFCs implemented the new vertical jet depth information in July 2006;

  3. the WAFCs completed the implementation of the operational BUFR encoded SIGWX data;

  4. the WAFCs implemented the production of WAFC output performance indicators available through the WAFSOPSG website;

  5. the ISCS X.25 protocol system was replaced with a TCP/IP compliant system on 31 July 2005;

  6. the WAFCs performed several successful planned and unplanned back-up activities;

  7. WAFC London experienced three short duration unplanned service interruptions;

  8. WAFC Washington experienced two short duration unplanned service interruptions;

  9. WAFC Washington resolved BUFR-encoded SIGWX quality issues with the assistance of Hong Kong, China;

  10. information to notify users of changes to the WAFS was included in the WAFSOPSG website; and

  11. PNG formatted WAFS SIGWX charts were added to SADIS services.

    1. The group is invited to review the management report given in the appendix to this paper, note its content and agree that its scope meets the intent of the WAFSOPSG Conclusion 1/3.

  1. ACTION by the wafsopsg

    1. The WAFSOPSG is invited to note the information in this paper.

      — — — — — — — —




World Area Forecast System

Management Report
London and Washington

World Area Forecast Centres
March 2005 through July 2006


F.1 In the final report of the WAFSOPSG/1 meeting, paragraph and Conclusion 1/3 placed the following action on the United Kingdom and the United States as the provider States of the World Area Forecast System (WAFS).
F.2 That, World Area Forecast Centre (WAFC) Provider States be invited to provide a concise joint WAFS management report, in the order of five pages, to be presented at every WAFSOPSG Meeting, covering the period elapsed since the previous meeting and addressing the main features of the WAFS operations, including ISCS and SADIS satellite broadcasts, highlighting any recent developments or difficulties and future plans for operational updates.
Note – In the case of SADIS, all details can be omitted by making reference to the latest SADIS management report.
F.3 This management report by the United Kingdom and the United States was developed to meet this requirement.
F.4 An Executive Summary of the main events is provided at the beginning of the report.

WAFCs London and Washington

July 2006

Executive Summary

E1. The WAFCs removed the WAFS wind and temperature charts in T4 format from the WAFS broadcasts on 1 July 2005.

E2. The WAFCs implemented the new vertical jet depth information in July 2006.
E3. The WAFCs completed the implementation of the operational BUFR encoded SIGWX data.
E4. The WAFCs implemented web pages for viewing WAFC performance statistical information.
E5. The ISCS X.25 protocol system was replaced with a TCP/IP compliant system on 31 July 2005.
E6. The WAFCs performed several successful planned and unplanned back-up activities.
E7. WAFC London experienced three short duration unplanned service interruptions.
E8. WAFC Washington experienced two short duration unplanned service interruptions.
E9. WAFC Washington resolved BUFR encoded SIGWX quality issues with the aid of Hong Kong, China.
E10. A website was established to notify users of changes to the WAFS.
E11. PNG formatted WAFS SIGWX charts were added to the three SADIS Services.

  1. Progress on the development of the WAFS

  2. Product Availability

      1. Cessation of WAFS T4 wind and temperature charts - On 1 July 2005, the ICAO wind and temperature charts in T4 format were removed from the WAFS broadcasts by both WAFCs. The cessation of these mature products was uneventful from the perspective of the WAFCs. WAFS users were informed well in advance of this action. However, a small number of users were clearly unprepared for the cessation of the charts.

      2. PNG formatted SIGWX available on SADIS FTP - During June 2005, SIGWX charts in PNG format produced by WAFC London were added to the SADIS FTP Service as required by WAFSOPSG Conclusion 2/13. These products were included as “unbulletinised” files to enable them to be displayed via a COTS (commercial-off-the-shelf) application. Comparable products prepared by WAFC Washington were added to the FTP Service during early October 2005, completing this activity.

      3. BUFR encoded SIGWX - On 1 July 2005, WAFC Washington began the operational production and distribution of WAFS SIGWX data in the BUFR code on the ISCS. The data was added to the SADIS 1G, 2G and FTP Service by the middle of July. This activity completed the implementation of WAFS BUFR encoded SIGWX data.

      4. PNG formatted SIGWX available on SADIS 1G and 2G - SADISOPSG/10 requested that the PNG formatted SIGWX products be added to the SADIS satellite services (SADIS 1G and 2G). This requirement was implemented by mid-September 2005 for all of the PNG formatted charts. To enable these charts to be transmitted via satellite a WMO telecommunication ‘envelope’ was assigned to each chart. For a product recipient to be able to display these charts this ‘envelope’ needs to be removed otherwise the client viewer does not recognize the chart as a PNG formatted image. To assist in this process some functional software was constructed by WAFC London and supplied to one of the users so that they could evaluate the utility of these charts.

      5. Jet Depth Information - In July 2006, both WAFS implemented the new jet depth format on the WAFS SIGWX charts. The new format uses the highest and lowest flight levels of the 80 knot jet wind core instead of the plus and minus notation.

      6. WAFS Output Performance Indicators

      7. WAFSOPSG Conclusion 2/11 invited the WAFCs to implement a number of measures that would quantify the accuracy and availability of specified WAFS products. In response to this conclusion, both WAFCs are pleased to report that web pages containing output performance indicator and timeliness statistics have been implemented. Each WAFC maintains a separate web site. The statistics are updated monthly.

      8. WAFC London performance indicators are available for viewing from the following URL: WAFC Washington performance indicators are available from the following URL: These pages provide RMS vector wind errors and RMS temperature errors for 6 geographic regions: North Atlantic, Asia, North Pacific, Northern Hemisphere, Tropics, and Southern Hemisphere. Timeliness of transmission for selected GRIB and BUFR bulletins are also made available.

      9. ISCS Broadcast Changes

      10. The replacement of the X.25 ISCS system with TCP/IP ISCS was completed on 31 July 2005. All registered satellite receive sites were upgraded by the contractor, Verizon/MCI. A few sites were not able to replace their X.25 compliant workstation with the new TCP/IP compliant workstations due to lack of local State funding. Changes at each site included: 1) setting the Very Small Aperture Terminal (VSAT) satellite equipment to the frequency of the new ISCS space segment; 2) installing the new network interface (Comtech satellite modem); 3) inspecting the antenna for excessive wear and refurbishing it if needed; 4) assisting the site in connecting their TCP/IP compliant workstation (if they had one) to the new interface; 5) installing Verizon/MCI provided PD Receive interface software into the workstation; 6) removal of the Memotec X.25 network interface; and 7) removal of the Hughes PES indoor unit.

      11. WAFS Workstation at WAFC Washington

      12. In December 2005, the GST/WAFS workstation located at SIGWX forecast desk at WAFC Washington was updated to receive and display WAFS BUFR encoded SIGWX data. This allowed the WAFS forecasters to begin a quality control process that included: 1) the verification of successful arrival of all BUFR encoded products at the workstation; and 2) the assurance that the rendering of the SIGWX from the BUFR was equivalent to the original forecast.

      13. WAFS Change Notice Board

      14. WAFSOPSG Conclusion 2/4 invited the WAFCs to develop a ‘tracking system’ for inclusion on the WAFSOPSG web site. The WAFCs are pleased to report that such a facility became available in May 2005 and is available from URL: This ‘Notice Board’ is updated on a regular basis by the WAFCs. Users are invited to access the page on a regular basis so that they remain up to date with developments pertaining to the WAFS.

      15. Representing WAFS SIGWX in BUFR” document updated

      16. A number of minor changes to the standard adopted for the visualization of the BUFR encoded SIGWX were implemented. Most of these changes apply to the way a client’s visualization software decodes and displays the data. One of the more significant changes includes revised guidance on how to correctly depict jet depth information in flight levels. All of these changes have been captured in the latest version (V3.0) of the document “Representing WAFS Significant Weather (SIGWX) in BUFR” which is available from URL A copy of this document has been circulated to all of the commercial suppliers of WAFS visualization software. Users are invited to review this document and take particular note of the document change history which details the changes that have been incorporated since the WAFSOPSG/2 meeting (March 2005).

      17. WAFC Backup

      18. The WAFCs carried out a series of backup tests during 2005 and 2006 to confirm the effectiveness of the current backup plan, which now also includes the BUFR encoded data. The backup test schedule and test results are available from the WAFSOPSG web site at URL: These backup tests were largely transparent to end users. Minor problems that occurred during the tests are detailed in section 2 below.

      19. Operational backup was used on a small number of occasions by WAFC London. These events were executed successfully.

  3. Developmental or Operational difficulties with the WAFS

  4. Service Interruptions

      1. There were three short-duration, unplanned service interruptions to the services from WAFC London during the period of this report.

    1. The first interruption occurred (26 October 2005) as a result of a small fire which affected the UPS which feeds computer hall 2 at the Met Office. Redundancy across the two computer halls at Exeter ensured that the interruption was limited to WAFC product creation (WAFC backup procedures were implemented); the three SADIS services stayed in operation.

    2. The second interruption (6 December 2005) was due to human error which resulted in a temporary power-down of computer hall 1. This event had an impact on all three SADIS services which were affected for up to several hours. When the individual services were brought back in to operation one-by-one, routine operation was re-established.

    3. The third interruption (3 January 2006) affected just the SADIS 2G service when one of the communication routers ‘locked-up’. The outage was restricted to approximately 1 hour.

      1. In addition to these three unplanned interruptions there were several occurrences towards the end of 2005 when OPMET and GRIB data was not correctly uploading onto the SADIS FTP service. Regrettably all of these occurrences were knock-on affects of earlier changes to the service primarily related to adding new products (e.g. KKCI BUFR data), and knock-on effects to the power-down in IT hall 1 (6 December 2005).

      2. WAFC London takes outages extremely seriously, particularly unplanned ones that have a direct effect on users. The SADIS provider regrets any negative impacts on user operations that may have occurred as a result of any of these outages and will continue to enhance service resilience during the next 12 months. The three unplanned outages detailed above resulted in action and change from the highest levels within the Met Office. In particular the following events have subsequently occurred with a view to mitigating similar occurrences:

      • A contractual relationship has been modified;

      • Further separation of systems and circuits between the two computer halls has been implemented;

      • Additional automatic system monitoring has been implemented;

      • Additional training of helpdesk operators has been carried out;

      • Internal guidance material has been reviewed and enhanced.

      1. On 16 May 2006 the NOAA Aviation Weather Center (AWC), which includes the SIGWX forecast operation of WAFC Washington, experienced two power outages and subsequent failure of emergency power system, which resulted in the need for WAFC-London to provide SIGWX forecasts for WAFC-Washington for two production cycles.  The failure of the emergency power system was caused by an underground cable failure which supplied power from the emergency diesel-powered generators.

      2. WAFC Washington SIGWX BUFR quality

      3. The software update on the GST/WAFS workstation located in the SIGWX forecaster section of WAFC Washington allowed WAFS forecasters to begin a quality control process of the BUFR encoded WAFS SIGWX data after December 2005. For several months WAFS Washington worked closely with the workstation vendor to improve the visualization software.

      4. WAFC Washington received a number of valuable comments accompanied by detailed examples of problems noted with the Washington BUFR data. This valuable feedback helped solve several problems associated both with the BUFR encoding software and the transmission procedures. WAFC Washington wishes to recognize the efforts of the Hong Kong Observatory for their help in solving these quality issues.

      5. Back-up

      6. During recent planned back-up exercises, WAFC Washington noted that BUFR-encoded SIGWX products generated for WAFC London did not appear to arrive at GST/WAFS workstations. (This was not the case when the products were transmitted normally by WAFC London.) The WAFCs, therefore, were not able to declare the Washington back-up of London SIGWX a complete success. Discussions with the GST software vendor have revealed that the BUFR products were likely arriving at the GST workstations, but being catalogued in the WAFC Washington product area based on information within the BUFR message identifying WAFC Washington as the originator of the message. A software update designed to remedy this problem was implemented in April 2006, and will be tested in July 2006.

  1. Future Plans

  2. PNG formatted SIGWX

      1. WAFC London received feedback from a number of users stating that they would like to see the PNG formatted WAFS SIGWX produced as an operational product. In addition it should be noted that the SADIS efficacy questionnaire concluded that less than 50% of SADIS users currently have the ability to produce Annex 3 compliant SIGWX charts from the BUFR encoded data. The WAFCs along with the SADISOPSG and a number of other stakeholders are of the opinion that serious consideration needs to be given to maintain the production and dissemination of the PNG formatted charts in parallel with the BUFR data.

      2. Termination of the SADIS 1G Service

      3. Conclusion 9/15 of the SADISOPSG requires the SADIS 1G service to be available in addition to the SADIS 2G service until 31 December 2008. This means that existing SADIS users have a little over two years to make the transition to the SADIS 2G Service before the legacy 1G service is terminated. Further information is available from

      4. International SADIS Seminars

      5. Two international SADIS seminars are scheduled to take place during 2006:

      • Bangkok 14-15 July 2006; and

      • Paris 25-26 September 2006

      1. The primary purpose of these events is to provide an opportunity for SADIS stakeholders to get together and discuss any issues associated with the migration from the legacy SADIS 1G service to the new SADIS 2G service. A high level of commitment to the seminars has been given by the hardware and software vendors. It is hoped that a good number of SADIS users will attend these events and take advantage of the unique opportunity provided to discuss their requirements with both hardware and software vendors. Both of the seminars are held back-to-back with other international meetings held at the ICAO regional offices in Bangkok and Paris and it is hoped that this will assist in securing wide participation.

      2. Enhancements to the SADIS FTP Service

      3. Following discussions at the recent SADISOPSG/11 meeting work is on-going to complete the implementation plan for a number of significant enhancements to the SADIS FTP Service. The enhancements include:

      • The implementation of a Public Key Infrastructure (PKI) that will enable digitally signed products to be issued via the service and for users to return a digital receipt confirming that a file has been received without error. In addition this technology will significantly enhance the process of user authentication and enable a full audit trail of distributed products to be constructed;

      • Implementation of additional security technologies that include Network Intrusion Prevention System (NIPS), and Host Intrusion Prevent System (HIPS); and

      • The development of a contingent service within IT hall 2, Exeter, UK.

      1. Working papers were submitted to WAFSOPSG/3 to document the plans for addressing a number of significant enhancements to the WAFS. These include:

  1. migration plan to the GRIB2 form;

  2. production of gridded icing, turbulence and embedded CB fields;

  3. issue of SIGWX data 17-hrs prior to validity;

  4. increases to the temporal and spatial resolution of WAFS upper wind forecasts;

  5. development of an objective icing index; and

  6. results from a further evaluation of WAFS visualization software.

Annex 1 – WAFC Meeting Participation
A.1.1 WAFC London
SADISOPSG/10, Paris 24-27 May 2005

APANPIRG CNS/MET SG, Bangkok, 11-15 July 2005

EANPG MetG, Paris, 19-23 September 2005

IAVWOPSG/2, Lima, 26-30 September 2005

IATA MET TF 16, Montreal 25-27 October 2005

SCRAG/6, Paris, 21-22 November 2005

SADISOPSG/11, Cairo, 23-25 May 2006

IATA MET TF 17, Montreal 11-12 April 2006

International SADIS Seminar, Bangkok, 14-15 July 2006

APANPIRG CNS/MET SG, Bangkok, 17-21 July 2006

A.1.2 WAFC Washington
AERMET, Mexico City, 23-27 May 2005

SADISOPSG/10, Paris, 24-27 May 2005

APANPIRG CNS/MET SG, Bangkok, 11-15 July 2005

EANPG MetG, Paris, 19-23 September 2005

IAVWOPSG/2, Lima, 26-30 September 2005

IATA MET TF 16, Montreal 25-27 October 2005

IATA MET TF 17, Montreal 11-12 April 2006

APANPIRG CNS/MET SG, Bangkok, 17-21 July 2006

Annex 2 – Useful Contact Points and Web Addresses (URLs)
A.2.1 WAFC London
WAFC London Manager: Mr. Nigel Gait Tel: +44 1392 886268; Fax: +44 1392 885681; Email:

WAFC London SADIS contact: TBN

SADIS Web Site

SADIS 2G Web Page

SADIS Admin Messages

SADIS Software Evaluations

SADIS Procurement Guidelines

SADIS News Page

SADIS Gateway Handbook
A.2.2 WAFC Washington
ISCS Program Coordinator: Mr. Robert Gillespie Tel: 01 301 713 9478 ext. 140; e-mail:

ISCS Program Leader: Mr. Patrick Gillis Tel. 01 301 713 1743 ext. 104; e-mail:

NWS International Aviation Weather Services Program Manager: Mr. Michael Mercer Tel. 01 301 713 1726 ext. 140; e-mail:

NWS/ISCS 24-hour Network Operations Technical Control Center: Tel: 01 301 713 0902; e-mail

NWS/Aviation Weather Center: Mr. Larry Burch Tel: 01 816 584 7203; e-mail:

ISCS Web Site

ISCS Admin Messages

ISCS Software Evaluations

A.2.3 ICAO
WAFS Operations Group

SADIS Operations Group

WAFC Backup Procedures

WAFC Backup Test Chronology

WAFC Backup Test Schedule

BUFR Guidelines Document

SADIS User List

SADIS User Guide

— END —

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