Manual of Aeronautical
Meteorological Practice

Approved by the Secretary General
and published under his authority

Sixth...
Published in separate English, French, Russian and Spanish editions by the International Civil Aviation Organization. All
...
Manual of Aeronautical
Meteorological Practice

IMPORTANT NOTE
This edition is compatible with the Fourteenth Edition of A...
AMENDMENTS
The issue of amendments is announced regularly i the ICAO Journal and i the
n
n
f
monthly Supplement to the Cat...
FOREWORD
1. The first edition of the Manual o Aeronautical
f
Meteorological Practice, published in response to recommendat...
TABLE OF CONTENTS
Page

.................................

(iii)

3.6
3.7
3.8

.

Chapter 1 Meteorological Services for
Av...
Manual on Aeronautical Meteorological Practice

(vi)

Page

Page

..................

9.2

6-1
6- 1
6- 1

6-3

..............
Table o Contents
f

(Vi0

Page
Appendix 9

.

Model charts and forms

.

........ A9-1

Appendix 10 Guidance on area forec...
Chapter 1
METEOROLOGICAL SERVICES FOR AVIATION

affect the safety of aircrafi operations are issued by
meteorological watc...
Manual o Aeronautical Meteorological Practice
f

1-2

General Meteorological Standards and Recommended
Practices, Educatio...
I-3

Chapter i. Meteorological Services for Aviation

1.4.2 In the areas prone to volcanic eruptions, aeronautical meteoro...
Chapter 2
METEOROLOGICAL OBSERVATIONS AND REPORTS

2.1 GENERAL

depending on regional air navigation agreements. When
requ...
Manual of Aeronautical Meteorolozical Practice

2-2

Example 2-1.

Routine reports in abbreviated plain language

a) Local...
Chapter 2. Meteorological Observations and Reports

2-3

2.3.4 m p e of report
(MET REPORT) - MET REPORT
(METAR) - METAR

...
Manual of Aeronautical Meteorological Practice

2-4

Table 2-1. Reporting procedures related to directional variations of ...
Chapter 2. Meteorological Observations and Reports

2-5

A > 20 krnlh (10 kt)

A 5 20 kmlh (10 kt)

I

Report disseminated...
Manual o Aeronautical Meteorological Practice
f

2-6

Table 2-3. Reporting procedures related to visibility - to be applie...
Chapter 2. Meteorological Observations and Reports

2- 7

Table 2-4. Additional reporting procedures related to RVR data i...
Manual o Aeronautical Meteorological Practice
f

2-8
~~

Table 2-5. Types of present weather phenomena
Type

Phenomenon

P...
Chapter 2. Meteorological Observations and Reports

2-9

Table 2-6. Characteristics of present weather phenomena
Abbreviat...
Manual o Aeronautical Meteorological Practice
f

2-10

an indication of intensity or proximity, as appropriate, should be ...
Chapter 2. Meteorological Observations and Reports

2-11

cloud, or cloud fragments, is given, followed by the relevant ab...
Manual of Aeronautical Meteorological Practice

2-12
2.3.15 Supplementary information

2.3.15.1 Local reports may also inc...
Chapter 2. Meteorological Observations and Reports

2-13

Table 2-8. Supplementary information for inclusion
in local rout...
Manual of Aeronautical Meteorological Practice

2-14

threshold value as agreed upon between the
meteorological authority,...
Chapter 2. Meteorological Observations and Reports

2-15

when the wind changes through values of operational significance...
Manual of Aeronautical Meteorological Practice

own duplicate displays (e.g. wind or RVR indicators), displays of automate...
2-1 7

Chapter 2. Meteorological Observations and Reports

2.12 REPORTS OF
VOLCANIC ACTIVITY
As mentioned in 1.4.2, aerona...
Chapter 3
FORECASTS

3.1 GENERAL

SIGMET and AIRMET information, aerodrome warnings
and wind shear warnings may refer to e...
3-2

Chapter 3. Forecasts

Table 3-1. ‘Qpes of aeronautical meteorological forecasts, including
SIGMET and AIRMET informat...
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
Doc 8896 manual of aeronautical meteorological practice
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Doc 8896 manual of aeronautical meteorological practice

  1. 1. Manual of Aeronautical Meteorological Practice Approved by the Secretary General and published under his authority Sixth Edition - 2004 Internat ionaI C ¡viI Av iation Organizat ion Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale --`,,```,,,,````-`-`,,`,,`,`,,`--- D o c 8896 AN189314
  2. 2. Published in separate English, French, Russian and Spanish editions by the International Civil Aviation Organization. All correspondence, except orders and subscriptions, should be addressed to the Secretary General. Orders should be sent to one of the following addresses, together with the appropriate remittance (by bank draft, cheque or money order) in U.S. dollars or the currency of the country in which the order is placed. Credit card orders (American Express, MasterCard and Visa) are accepted a t ICAO Headquarters. International Civil Aviation Organization. Attention: Document Sales Unit, 999 University Street, Montréal, Quebec, Canada H3C 5H7 Telephone: +1 (5 14) 954-8022; Facsimile: +1 (514) 954-6769; Sitatex: YULCAYA; E-mail: sales@icao.int; World Wide Web: http://www.icao.int China. Glory Master International Limited, Room 434B, Hongshen Trade Centre, 428 Dong Fang Road, Pudong, Shanghai 200120 Telephone: +86 137 0177 4638; Facsimile: +86 21 5888 1629; E-mail: glorymaster@online.sh.cn Egypt. ICAO Regional Director, Middle East Office, Egyptian Civil Aviation Complex, Cairo Airport Road, Heliopolis, Cairo 11776 Telephone: +20 (2) 267 4840; Facsimile: +20 (2) 267 4843; Sitatex: CAICAYA; E-mail: icao@idsc.net.eg France. Directeur régional de l’OAC1, Bureau Europe et Atlantique Nord, 3 bis, villa Émile-Bergerat, 92522 Neuilly-sur-Seine (Cedex) Téléphone: +33 (1) 46 41 85 85; Fax: +33 (1) 46 41 85 00; Sitatex: PAREUYA; Coumel: icaoeurnat@paris.icao.int Germany. UNO-Verlag GmbH, Am Hofgarten 10, D-53113 Bonn / Telephone: +49 (O) 2 28-9 49 O 20; Facsimile: +49 (O) 2 28-9 49 02 22; E-mail: info@uno-verlag.de; World Wide Web: http://www.uno-verlag.de India. Oxford Book and Stationery Co., Scindia House, New Delhi 110001 or 17 Park Street, Calcutta 700016 Telephone: +91 (11) 331-5896; Facsimile: +91 (11) 332-2639 Japan. Japan Civil Aviation Promotion Foundation, 15-12, 1-chome, Toranomon, Minato-Ku, Tokyo Telephone: +81 (3) 3503-2686; Facsimile: +81 (3) 3503-2689 Kenya. ICAO Regional Director, Eastern and Southern African Office, United Nations Accommodation, P.O. Box 46294, Nairobi Telephone: +254 (20) 622 395; Facsimile: +254 (20) 623 028; Sitatex: NBOCAYA; E-mail: icao@icao.unon.org Mexico. Director Regional de la OACI, Oficina Norteamérica, Centroamérica y Caribe, Av. Presidente Masaryk No. 29, 3e‘ Piso, Col. Chapultepec Morales, C.P. 11570, México D.F. I Teléfono: +52 (55) 52 50 32 11; Facsimile: +52 ( 5 5 ) 52 03 27 57; Correo-e: icao-nacc@mexico.icao.int Nigeria. Landover Company, P.O. Box 3165, Ikeja, Lagos Telephone: +234 (1) 4979780; Facsimile: +234 (1) 4979788; Sitatex: LOSLORK; E-mail: aviation@landovercompany.com Peru. Director Regional de la OACI, Oficina Sudamérica, Apartado 4127, Lima 100 Teléfono: +51 ( i ) 575 1646; Facsimile: +51 ( I ) 575 0974; Sitatex: LIMCAYA; Correo-e: mail@lima.icao.int Russian Federation. Aviaizdat, 48, Ivan Franko Street, Moscow 121351 / Telephone: +7 (095) 417-0405; Facsimile: +7 (095) 417-0254 Senegal. Directeur régional de l’OACI, Bureau Afrique occidentale et centrale, Boîte postale 2356, Dakar Téléphone: +221 839 9393; Fax: +221 823 6926; Sitatex: DKRCAYA; Courriel: icaodkr@icao.sn Slovakia. Air Traffic Services of the Slovak Republic, Letové prevádzkové sluzby Slovenskej Republiky, State Enterprise, Letisko M.R. Stefánika, 823 07 Bratislava 21 / Telephone: +421 (7) 4857 1111; Facsimile: +421 (7) 4857 2105 South Africa. Avex Air Training (Pty) Ltd., Private Bag X102, Halfway House, 1685, Johannesburg Telephone: +27 (1 i ) 315-0003/4; Facsimile: +27 (1 1) 805-3649; E-mail: avex@iafrica.com Spain. A.E.N.A. - Aeropuertos Españoles y Navegación Aérea, Calle Juan Ignacio Luca de Tena, 14, Planta Tercera, Despacho 3. 11, 28027 Madrid / Teléfono: +34 (91) 321-3148; Facsimile: +34 (91) 321-3157; Correo-e: sscc.ventasoaci@aena.es Switzerland. Adeco-Editions van Diermen, Attn: Mr. Martin Richard Van Diermen, Chemin du Lacuez 41, CH-1807 Blonay Telephone: +41 021 943 2673; Facsimile: +41 021 943 3605; E-mail: mvandiermen@adeco.org Thailand. ICAO Regional Director, Asia and Pacific Office, P.O. Box 11, Samyaek Ladprao, Bangkok 10901 Telephone: +66 (2) 537 8 189; Facsimile: +66 (2) 537 8199; Sitatex: BKKCAYA; E-mail: icao-apac@bangkok,icao.int United Kingdom. Airplan Flight Equipment Ltd. (AFE), l a Ringway Trading Estate, Shadowmoss Road, Manchester M22 5LH Telephone: +44 161 499 0023; Facsimile: +44 161 499 0298; E-mail: enquiries@afeonline.com; World Wide Web: http://www.afeonline.com 3/04 Catalogue of ICAO Publications and Audio-visual Training Aids Issued annually, the Catalogue lists all publications and audio-visual training aids currently available. Monthly supplements announce new publications and audio-visual training aids, amendments, supplements, reprints, etc. Available free from the Document Sales Unit, ICAO. --`,,```,,,,````-`-`,,`,,`,`,,`--- Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale
  3. 3. Manual of Aeronautical Meteorological Practice IMPORTANT NOTE This edition is compatible with the Fourteenth Edition of Annex 3, including Amendment 72 (applicable 1 November 2001). An amendment is being prepared by ICA0 to render the manual compatible with the Fifteenth Edition of Annex 3, including Amendment 73 (applicable 25 November2004). Approved by the Secretary General and published under his authority Sixth Edition -2004 I nt ernationaI Civ iI Av¡ ation Organizat ion Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale --`,,```,,,,````-`-`,,`,,`,`,,`--- Doc 8896 ANI89314
  4. 4. AMENDMENTS The issue of amendments is announced regularly i the ICAO Journal and i the n n f monthly Supplement to the Catalogue o ICAO Publications and Audio-visual Training Aids, which holders of this publication should consult. The space below is provided to keep a record of such amendments. RECORD OF AMENDMENTS AND CORRIGENDA No. --`,,```,,,,````-`-`,,`,,`,`,,`--- Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale Date of issue Date Entered entered bY
  5. 5. FOREWORD 1. The first edition of the Manual o Aeronautical f Meteorological Practice, published in response to recommendations made by the Meteorology and Operations Divisional Meeting? (Paris, 1964), was intended as a guide for use by pilots and other aeronautical personnel on meteorological procedures, codes, symbols and abbreviations. It also contained a multilingual list of terms and phrases commonly used in meteorological briefings. . concerning information on weather phenomena hazardous to low-level flights (AIRMET and GAMET messages) were introduced. However, the basic structure of the manual was maintained. 6. The sixth edition reflects the substantial changes made to Annex 3 in Amendments 71 and 72. 7. The body of the manual is still based primarily on Annex 3, summarized and enlarged upon, where necessary. The appendices provide: 2. A second edition was prepared in 1977 to reflect, in particular, the many changes in procedures and terminology recommended by the Eighth Air Navigation Conference and the Meteorology Divisional Meeting2 (1974). a) detailed information on aeronautical meteorological codes, model forms and charts used for documentation, etc., which are dispersed throughout various ICAO and World Meteorological Organization (WMO) documents, and whose consolidation in the manual provides users with a single reference document for most of their day-to-day needs in aeronautical meteorological practice; 3. As demand for the manual continued to grow and because further important changes to meteorological procedures had taken place, particularly in connection with the recommendations for the establishment of a world area forecast system (WAFS) made by the Communications/ Meteorology Divisional Meetin$ (Montréal, 1982), a third edition was prepared. This edition was rewritten aiming to meet the needs of operational aeronautical meteorologists, as well as the needs of pilots and other aeronautical personnel. b) information on other subjects such as location of instruments at aerodromes and use of meteorological information by flight operations officers. --`,,```,,,,````-`-`,,`,,`,`,,`--- 4. As a consequence of an extensive amendment proposal to Annex 3 developed by the Communications/ MeteorologyíOperations (COM/MET/OPS) Divisional Meeting4 (1990) including, in particular, provisions regarding the transition to the final phase of the WAFS, aerodrome observations, reports and forecasts, SIGMET information, etc., a fourth edition of the manual was published. In order to continue to meet users? requirements, however, the structure of the manual was not changed. 8. Annex 3 is a constantly evolving document, as are all ICAO Annexes. Some procedures described in this manual are currently under review by the Air Navigation Commission and may have changed by the time it is printed and issued. However, the usual amendment service for ICAO documents will keep users of this manual up to date, on a timely basis, on changes of this kind. 5. The fifth edition is the direct result of Amendment 70 to Annex 3, applicable fiom 1 January 1996, which constituted a comprehensive update of the provisions, in particular, those related to air-reporting and the observation and reporting of wind shear. In addition, new provisions 9. In conclusion, it should be stressed that the material in this manual is intended for guidance only. It is not intended to replace relevant national instructions, or explanatory material, such as the explanations of codes and symbols, normally shown in flight documentation, nor is it intended to cover the many non-aeronautical uses of meteorological information. Nothing in this manual should be taken as contradicting or conflicting with Annex 3 provisions or any other Standards, Recommended Practices, procedures or guidance material published by ICAO or WMO. It should also be noted that in this manual the words ?shall? or ?should? are not used in a regulatory sense as in ICAO or WMO regulatory documents. Held conjointly with the Third Session of the Commission for Aeronautical Meteorology (CAeM) of the WMO. 2. Held, in part, conjointly with the Extraordinary Session (1974) of the body mentioned in Note 1. 3. Held conjointly with the Seventh Session of the body mentioned in Note 1. 4. Held conjointly with the Ninth Session of the body mentioned in Note 1 . 1. (iii) Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale
  6. 6. TABLE OF CONTENTS Page ................................. (iii) 3.6 3.7 3.8 . Chapter 1 Meteorological Services for Aviation 1.1 General ........................... 1.2 Meteorological offices ............... 1.3 Meteorological watch offices........... 1.4 Meteorological stations .............. 1.5 World area forecast centres (WAFCs) ... 1.6 Tropical cyclone advisory centres (TCACs) .......................... 1.7 Volcanic ash advisory centres (VAACs) . .................................. . Chapter 2 Meteorological Observations and Reports 2.1 General ........................... 2.2 Aerodrome observations and reports.... 2.3 Routine reports ..................... 2.4 Local special reports ................ 2.5 Special reports in the SPEC1 code form ............................. 2.6 Information on meteorological conditions for aircraft taking off and landing ........................ 2.7 Representativeness and accuracy aerodrome reports .................. 2.8 Weather radar observations and reports ............................ 2.9 Aircraft observations and reports (AIREP) .......................... 2.10 Basic surface and upper-air observations ....................... 2.11 Meteorological satellite data .......... 2.12 Reports of volcanic activity........... .............................. . ...................... Chapter 3 Forecasts 3.1 General ........................... 3.2 Accuracy of aeronautical meteorological forecasts ............. 3.3 Types of aeronautical meteorological forecasts .......................... 3.4 Aerodrome forecasts ................ 3.5 Amended aerodrome forecasts......... Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS 1-1 1-1 1-2 1-2 1-2 1-3 3.9 3.10 3.11 1-3 1-3 3.12 3.13 2-1 2- 1 2- 1 2-2 2-12 2-14 2-15 2-16 2-16 3-1 3-1 3-1 3-1 3-1 3-6 3-6 3-9 3-9 3-9 3-10 3-13 3-13 3-14 . Chapter 4 SIGMET Information. %pical Cyclone and Volcanic Ash Advisory Information. AIRMET Information. Aerodrome Warnings and Wind Shear Warnings 4-1 4.1 General ........................... 4-1 4.2 SIGMET information................ 4-1 4.3 Tropical cyclone and volcanic ash advisory infomation ................ 4-5 4.4 AIRMET information ............... 4-7 4.5 Aerodrome warnings ................ 4-9 4.6 Wind shear warnings ................ 4-10 .................. 2-16 2-16 2-16 2-17 Trend-type landing forecasts .......... Forecasts for take.off ................ Forecasts of en-route conditions . general ........................... Forecasts of upper winds and upper-air temperatures....................... Forecasts of significant en-route weather phenomena ................. Exchanges of forecasts of en-route conditions between meteorological offices ............................ Amendments to forecasts of en-route conditions......................... Area forecasts for low-level flights exchanged between meteorological ofices in support of the issuance of AIRMET information ............. . Chapter 5 Meteorological Service for Operators and Flight Crew Members 5.1 General provisions .................. 5.2 he-flight information ............... 5.3 Briefing. consultation and display...... 5.4 Flight documentation - methods of presentation ....................... Flight documentation . forecasts of 5.5 en-route conditions ................. 5.6 Flight documentation . aerodrome forecasts .......................... 5.7 Automated pre-flight information systems ........................... Not for Resale ......... 5-1 5-1 5-2 5-3 5-3 5-4 5-5 5-5 --`,,```,,,,````-`-`,,`,,`,`,,`--- Foreword Page
  7. 7. Manual on Aeronautical Meteorological Practice (vi) Page Page .................. 9.2 6-1 6- 1 6- 1 6-3 ................................... ........................ 6-4 7-1 7- 1 7- 1 7-1 7-2 7-3 7-5 7-5 .................... Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS . Appendix 1 Information on the world area forecast system (WAFS) 1. General description of the WAFS ......... 2. Evolution of the system ............... 3. Planning of the WAFS ................ 4 . Authorized access to the WAFS satellite broadcast ........................... 5 . Duties of meteorological offices in the context of the WAFS............... ................ 10-1 10-1 10-2 10-3 a1-1 a1-1 a1-1 a1-1 a1-2 a1-3 . Appendix 2 Technical specifications for local routine reports. local special reports and reports in the METAWSPECI code forms . . Appendix 3 Abbreviated decade of METAR and SPEC1 messages 7-5 . ....................... Appendix 4 Selected criteria applicable to aerodrome reports A2-1 A3-1 ......................... A41 Appendix 5 Location of instruments and accuracy of observations at aerodromes a51 7-6 8-1 8-1 8-1 . 8-2 ....... Part 1 . Location of instruments............. A5-1 Part 2 . Operationally desirable and currently attainable accuracy of measurement or observation.............................. 8-2 . Appendix 6 Operationally desirable accuracy of forecasts . . Chapter 9 Information on Aeronautical Meteorological Services in Aeronautical Information Publications 9.1 Nature of aeronautical information publications ....................... ........... LIST OF APPENDICES . Chapter 8 Coordination Between Aeronautical Meteorological Services and ATS and SAR Units 8.1 General ............................ 8.2 Meteorological information required by ATS units....................... 8.3 Meteorological information provided by ATS units....................... 8.4 Coordination between ATS units and meteorological offices and stations . . . . . . Chapter 10 Relevant Documents 10.1 ICAO documents of a specifically meteorological nature ............... 10.2 WMO documents................... 10.3 Other ICAO documents.............. 6-3 . Chapter 7 Aircraft Observations and Reports 7.1 General ........................... 7.2 Reporting of aircraft observations during flight ....................... Routine aircraft observations .......... 7.3 7.4 Special and other non-routine aircraft observations ....................... 7.5 Content of air.reports ................ 7.6 Criteria for reporting meteorological and related parameters in automated air-reports ......................... 7.7 Exchange of air-reports .............. 7.8 Recording and post-flight reporting of aircraft observations of volcanic activity ........................... 7.9 Detailed instructions concerning the retransmission of air-reports received by MWOs ......................... Information concerning MET services in aeronautical information publications . 9 - 1 ....................... Appendix 7 Technical specifications for aerodrome forecasts in the TAP code form 9-1 9- 1 A6-1 ..... . Criteria for trend-type landing .................................. Appendix 8 forecasts Not for Resale A5-13 A7-1 a5-1 --`,,```,,,,````-`-`,,`,,`,`,,`--- . Chapter 6 Dissemination of Aeronautical Meteorological Information 6.1 General ........................... 6.2 Dissemination of OPMET information on the AFTN ...................... 6.3 Dissemination of aeronautical meteorological information on circuitdsystems other than the AFTN ... 6.4 Interrogation procedures for international OPMET databanks ....... 6.5 Dissemination of aeronautical meteorological information to aircraft in flight ...........................
  8. 8. Table o Contents f (Vi0 Page Appendix 9 . Model charts and forms . ........ A9-1 Appendix 10 Guidance on area forecasts in abbreviated plain language .................. Alo-1 Pari 1 . Format for abbreviated plain-language significant weather forecast messages and amendments thereto to serve international civil aviation in operations above flight level250................................ Alo-1 Part 2 . Format for abbreviated plain-language significant weather forecast messages and amendments thereto to serve international civil aviation in operations between flight levels 100 and 250 ............................. A104 Part 3 . Format for messages containing abbreviated plain-language amendments to upper-air forecasts ........................ ................................ Alo-6 All-1 . Appendix 12 List of tropical cyclone advisory centres and volcanic ash advisory centres ............................ A12-1 . ..................... --`,,```,,,,````-`-`,,`,,`,`,,`--- Not for Resale A13-1 A13-2 . Appendix 14 Use of meteorological information for pre-flight planning by operators and flight crew A14-1 1. Introduction ......................... A14-1 2 . Take-off and climb-out ................ A14-1 3. Cruise to top of descent................ A14-2 4 . Landing calculations .................. A14-7 ................... . Appendix 15 Commonly used abbreviations in meteorological messages .................. A151 . Appendix 16 Criteria for reporting meteorological and related parameters in automated air-reports 1. Wind direction ....................... 2. Wind speed .......................... 3 . Wind quality flag ..................... 4 . Temperature ......................... 5. Turbulence .......................... 6 . Humidity............................ . Appendix 13 An operational wind shear and inversion warning system for Helsinki-Vantaa airport A13-1 1. The measuring site and airport .......... A13-1 2. System configuration .................. A13-1 Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS 3. Weather-watch ....................... 4 . Routine warning services and use of mast data ......................... .................... . Appendix 1 Technical specifications for 1 SIGMET and AIRMET messages and special air-reports Page Appendix 17 Notification of WAFC concerning Significant discrepancies 1. Purpose of the report .................. 2. Usefulness of the report for the WAFCs . . 3. Steps to be followed by a meteorological office .............................. 4 . Steps to be followed by a WAFC ........ Attachment to Appendix 17 A161 A16-1 A16-1 A 16-1 A16-1 A16-1 A16-2 .......... A17-1 A17-1 A17-1 A17-1 A17-1 ................ A17-2
  9. 9. Chapter 1 METEOROLOGICAL SERVICES FOR AVIATION affect the safety of aircrafi operations are issued by meteorological watch offices (MWOs) (see 1.3). In the specific case of SIGMET information related to tropical cyclones and volcanic ash, specialized advisory information is required to support the preparation of these SIGMET information messages in meteorological watch offices. Tropical cyclone advisory centres (TCACs) and volcanic ash advisory centres (VAACs) (see 1.6 and 1.7) prepare and disseminate such advisory information. 1.1 GENERAL 1.1.I Meteorological services for international aviation are provided by meteorological authorities designated by States. Details of the services to be provided for international aviation are determined by each State in accordance with the provisions of ICAO Annex 3 and with due regard for regional air navigation agreements, which apply to specific areas designated as air navigation regions by ICAO. Each State also establishes a suitable number of meteorological offices, i.e. aerodrome meteorological offices, meteorological watch offices, other offices and aeronautical meteorological stations. Meteorological offices and aeronautical meteorological stations provide information required for operational planning, flight operations, the protection of aeronautical equipment on the ground, and for various other aeronautical uses. The information provided includes observations and reports of actual weather conditions at aerodromes and forecasts dealt with in Chapter 3; it is made available at aerodrome meteorological offices and is disseminated as appropriate to aeronautical users, including operators, flight crew members, air trafic services (ATS) units, search and rescue (SAR) units, airport management and others concerned with the conduct or development of international air navigation. 1.1.4 The responsibility for the provision of meteorological service for international air navigation mentioned in 1.1.I rests with the meteorological authority designated by each State. The meteorological authority may wish to provide the service or may arrange for the provision of the service by other providers on its behalf. 1.1.5 In order to meet the objectives of meteorological service for international air navigation and provide users with the assurance that the service, including the meteorological information provided, comply with the aeronautical requirements, the meteorological authority should establish and implement a properly organized quality system in accordance with the International Organization for Standardization (ISO) 9000:2000 Series quality assurance standards. The system should be certified by an approved organization. 1.1.2 Forecasts of en-route conditions, except forecasts for low-level flights issued by meteorological offices, are normally prepared by world area forecast centres (WAFCs) (see 1.5 below). This ensures the provision of high quality and uniform forecasts for flight planning and flight operations. It also permits meteorological watch offices to concentrate on keeping watch on weather conditions in their flight information regions (FIRS), and meteorological ofices at aerodromes to concentrate on local aerodrome forecasting, to keep watch over local (aerodrome) conditions and to issue warnings of weather conditions that could adversely affect operations and facilities at the aerodrome (e.g. aerodrome and wind shear warnings). 1.1.6 Properly educated and trained personnel should be employed in the provision of meteorological service for international air navigation. It is, therefore, an important responsibility of the meteorological authority to ensure that widely recognized standards are applied to the qualifications, education and training of all of the personnel involved in the provision of meteorological service for international air navigation. As far as the meteorological personnel are concerned, the requirements of the World Meteorological Organization (WMO) should be applied. 1.1.3 SIGMET and AIRMET information concerning the occurrence of specified en-route phenomena which may Note I .- The requirements are given in the WMO Publication No. 49, Technical Regulations, Volume I - Note.- Specific guidance on this subject is intended to be issued. --`,,```,,,,````-`-`,,`,,`,`,,`--- Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale
  10. 10. Manual o Aeronautical Meteorological Practice f 1-2 General Meteorological Standards and Recommended Practices, Education and Training. Note 2.- It may be noted that education and training in aeronautical meteorology o aeronautical personnel (e.g. f pilots, ATC personnel, flight dispatch officers, etc.), required by the aeronautical authorities concerned, should comply with the relevant ICA0 documents (e.g. Training Manual, Part F-1 - Meteorology for Air Traffic Controllers and Pilots (Doc 7192). 1.2 METEOROLOGICAL OFFICES Meteorological offices serving aviation are normally located at aerodromes, in which case they are called aerodrome meteorological offices. In addition to maintaining a continuous survey of meteorological conditions over the aerodrome(s) under their responsibility, preparing forecasts of local meteorological conditions, aerodrome warnings and wind shear warnings, these offices also provide bnefing, consultation and flight documentation or other meteorological information, display weather charts, reports, forecasts, meteorological satellite images and information derived from ground-based weather radar (radar network). Much of the information is obtained from WAFCs or from other meteorological offices (which may be located in a different country). Furthermore, meteorological ofices supply meteorological information to aeronautical users and exchange meteorological information with other meteorological offices. This also includes the exchange of operational meteorological (OPMET) data required by regional air navigation agreement. In addition, where necessary, meteorological offices supply the information regarding pre-emption activity, volcanic ash eruptions or the presence of volcanic ash in the atmosphere to their associated air traffic services (ATS) units, the aeronautical information services (AIS) units and the meteorological watch ofices (MWO) concerned, as agreed between the ATS, AIS and meteorological authorities concerned. However, not all aerodromes have a meteorological office and for such aerodromes the national aeronautical information publications (AIPs) indicate the name and location of the meteorological office designated to supply meteorological information concerning the aerodrome to operators, ATS units and others concerned. 1.3 METEOROLOGICAL WATCH OFFICES 1.3.1 States accepting responsibility for an FIR have to either designate a meteorological watch office (MWO) to serve that FIR or delegate the responsibility to another MWO. The MWOs so designated are listed in the relevant air navigation plans to indicate the overall integrity of the plan. They maintain a continuous watch over meteorological conditions affecting the flight operations within their areas of responsibility, issue information on the occurrence or expected occurrence of specified hazardous enroute weather conditions which may affect the safety of aircraft and low-level aircraft opera?ions (SIGMET and AIRMET information, respectively) and supply this and other weather information to their associated ATS units, usually a flight information centre (FIC) or an area control centre (ACC). In addition, MWOs exchange SIGMET information issued by other MWOs as required by regional air navigation agreement. The AIRMET information issued is transmitted to MWOs and meteorological offices in adja) cent FIRS (for details see Chapter 4. In preparing SIGMET and AIRMET information, MWOs normally make use of special air-reports, satellite and radar data and, to the extent decided by the meteorological authority, forecasts obtained from WAFCs. 1.3.2 MWOs also supply the information received on pre-emption volcanic activity, volcanic eruptions and volcanic ash clouds, for which a SIGMET information has not already been issued, to their associated ACCsíFICs, and in accordance with regional air navigation agreement, to the VAACs concerned. It is also the responsibility of MWOs to supply information received concerning an accidental release of radioactive materials into the atmosphere within the area of their responsibility to their associated ACC(s)/ FIC(s) and to the relevant AIS units, as agreed by the ATS, AIS and the meteorological authorities concerned. This information is usually obtained from the WMO regional specialized meteorological centre (RSMC) which specializes in the provision of computer generated transport model products for radiological environmental emergency response. 1.4 METEOROLOGICAL STATIONS 1.4.1 The actual weather observations at aerodromes and offshore structures are made by aeronautical meteorelogical stations which are situated at most of those facilities. Aeronautical meteorological stations may also be established at other points of significance to international air navigation. The specific types of observations and related reports are disseminated either locally, or to other aerodromes, as required, in accordance with regional air navigation agreement. --`,,```,,,,````-`-`,,`,,`,`,,`--- Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale
  11. 11. I-3 Chapter i. Meteorological Services for Aviation 1.4.2 In the areas prone to volcanic eruptions, aeronautical meteorological stations make observations regarding volcanic activity and volcanic eruptions. These observations form the basis for the issuance of volcanic activity reports. Details on the content and dissemination of such reports are given in 2.12. 1.5 WORLD AREA FORECAST CENTRES (WAFCs) 1.5.1 World area forecast centres (WAFCs) are components of the world area forecast system (WAFS), which is designed to primarily supply meteorological offices with forecasts of en-route meteorological conditions (i.e. forecasts of upper-air data and significant weather forecasts) suitable, as far as practicable, for direct use by operators, flight crew members, ATS units and other aeronautical users. Forecasts of global upper winds, upper-air temperatures, tropopause heights, maximum winds and humidity data in the binary GRiB code form for direct input into meteorological andor flight planning computers are also supplied by this system. In the near future, significant weather forecasts will be prepared by WAFCs in binary data format using WMO BUFR code form. B --`,,```,,,,````-`-`,,`,,`,`,,`--- 1.5.2 The WAFS consists of two WAFCs. The WAFCs issue global forecasts of upper winds, temperatures, tropopause heights, maximum winds and humidity, as well as forecasts of significant weather phenomena, in digital and/or pictorial form. WAFCs also issue amendments to these forecasts in abbreviated plain language in accordance with specified criteria. Note.- Further information on the WAFS and its evolution is given in Appendix i. MWOs, providers of international operational meteorological (OPMET) databanks established by regional agreement, providers of the (AFS) satellite distribution systems and, as necessary, other TCACs with advisory information regarding the position of a tropical cyclone centre, its forecast direction and speed of movement, central pressure and maximum surface wind near the cyclone centre. The advisory information is to be used by MWOs in support of the issuance of SIGMET information for tropical cyclones and an outlook, should be included in these SIGMET. 1.7 VOLCANIC ASH ADVISORY CENTRES (VAACS) 1.7.1 VAACs are meteorological centres designated by regional air navigation agreement on advice from WMO. They monitor relevant satellite data to detect volcanic ash in the atmosphere. Subsequently, VAACs run volcanic ash numerical trajectory dispersion models to forecast the movement of a volcanic ash cloud. As a result, the VAACs provide, as required, MWOs, ACCs, FICs, NOTAM offices, WAFCs, providers of international OPMET databanks established by regional air navigation agreement, providers of AFS satellite distribution systems, and other VAACs, with advisory information regarding the lateral and vertical extent and forecast movement of volcanic ash in the atmosphere following volcanic eruptions. The advisory information is to be used by MWOs in support of the issuance of SIGMET information on volcanic ash clouds and an outlook should be included in these SIGMET. The information is also made available, through the aeronautical fixed telecommunication network (AFTN), to aeronautical users. 1.6 TROPICAL CYCLONE ADVISORY CENTRES (TCACs) 1.7.2 VAACs form part of the ICAO International Airways Volcano Watch (IAVW). The international arrangements set up within the IAVW are aimed at monitoring volcanic ash in the atmosphere and providing warnings to aircraft of volcanic ash and associated volcanic activity. TCACs are meteorological centres designated by regional air navigation agreement on advice from WMO. They monitor the development of tropical cyclones in their areas of responsibility, using geostationary and polar-orbiting satellite data and other meteorological information. Based on these input data and information, TCACs provide Note.- Detailed information on the IAVWcan be found in the Manual on Volcanic Ash, Radioactive Material and Toxic Chemical Clouds (Doc 9691) and in the Handbook on the International Airways Volcano Watch (IAVW) Operational Procedures and Contact List (Doc 9766) and also on the ICAO website. Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale
  12. 12. Chapter 2 METEOROLOGICAL OBSERVATIONS AND REPORTS 2.1 GENERAL depending on regional air navigation agreements. When required as a result of specified operationally significant changes in weather conditions, special observations and reports are made whenever such changes occur between routine observations (see 2.4 and 2.5). 2.1.1 Observations of meteorological conditions are made by means of instruments and visual estimation and are used for landing and take-off, en-route navigation and flight performance, and as a basis for forecasting. Those observations used primarily for aircraft operations are called “operational meteorological (OPMET) data” while those used primarily for forecasting purposes are considered to be “basic meteorological data”. Some observations are used for both purposes. OPMET data include aerodrome observations, landing forecasts, aerodrome forecasts, SIGMET information and AIRMET information. Basic meteorological data include synoptic surface and upper air observations, satellite information, weather radar data and aircraft observations. OPMET data are described in detail below. 2.2.2 Observational data are combined into a report for dissemination at the local aerodrome or beyond (see Examples 2-1 and 2-2). Depending on their use, the reports are presented in two forms, i.e. as local reports in abbreviated plain language intended for dissemination and use at the aerodrome of ongin or as reports in the METAR and SPECI code forms (METARs and SPECIs), prescribed by WMO intended for the dissemination and use beyond the aerodrome of origin. 2.2.3 The need to provide aeronautical users with the two reports, one for local aerodrome use and one for the use beyond the aerodrome, is to meet operational requirements as follows: 2.1.2 At many locations, observations are made by use of automatic observing equipment. The equipment normally forms part of an integrated automatic or semiautomatic system, with displays at local aeronautical meteorological station(s), meteorological office(s), briefing facilities and ATS units. This automatic observing equipment provides for the manual insertion of weather elements which the equipment is not capable of observing. - local reports for aircraft about to land or take off including requirements for ATIS broadcasts and D-ATIS transmissions; and - METARsISPECIs for flight planning and en-route flight information service purposes, including requirements for VOLMET broadcasts and D-VOLMET transmissions. Note.- it should be noted that Human Factors prinf ciples should be observed in the design o these systems as well as of other systems and equipment used in the provision of meteorological service to international air navigation. Guidance material on the matter is given in the Human Factors Training Manual (Doc 9683). The information in both reports, therefore, differs slightly to fully reflect the respective operational requirements. Technical specifications for local routine reports, local special reports and reports in the METAR and SPECI code forms are reproduced in Appendix 2, including an extensive set of detailed examples relating to individual portions and groups in the reports. The appendix also contains technical specifications concerning trend-type landing forecasts, which are often attached to local reports and reports in the METAWSPECI code forms. These forecasts are dealt with in 3.6. 2.2 AERODROME OBSERVATIONS AND REPORTS 2.2.1 At aerodromes, routine observations are normally made and reported at hourly or half-hourly intervals 2-1 --`,,```,,,,````-`-`,,`,,`,`,,`--- Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale
  13. 13. Manual of Aeronautical Meteorolozical Practice 2-2 Example 2-1. Routine reports in abbreviated plain language a) Local routine reports disseminated locally at the aerodrome: MET REPORT YUDO* 2216302 WIND 240118KMH VIS 600M R W 1 2 RVR 1000M FG MOD DZ CLD SCT 300M OVC 600M T I 7 DP16 QNH 1018HPA b) Routine report in the METAR code form disseminated beyond the aerodrome: METAR YUDO’221630Z 24015KMH 0600 R12/1000U FG DZ SCT O100 OVC020 17/16 QI018 Meaning of both reporis: Local routine report or routine report in the METAR code form for Donlon/lnternational* issued on the 22nd of the month at 1630 UTC; surface wind direction 240 degrees; wind speed 18 or 15 kilometres per hour (averaged over 2 or 10 minutes, respectively); visibility 600 metres; runway visual range representative of the touchdown zone for runway 12 is 1 O00 metres (averaged over 1 or 10 minutes, respectively), (only for reports disseminated beyond aerodrome: the runway visual range values have shown a distinct upward tendency during previous 10 minutes); fog and moderate drizzle; scattered cloud at 300 metres, overcast at 600 metres; air temperature 17 degrees Celsius; dew-point temperature 16 degrees Celsius; QNH I018 hectopascals. * Fictitious location 2.3 ROUTINE REPORTS --`,,```,,,,````-`-`,,`,,`,`,,`--- 2.3.1 Paragraphs 2.3.3 to 2.3.14 deal with the content and format of routine reports; both those in abbreviated plain language disseminated locally (referred to below as local routine reports or MET REPORTS) and those disseminated beyond the aerodrome of origin (referred to as reports in the METAR code form or METARs). Local -special reports (referred to as SPECIALS) and special reports disseminated beyond the aerodrome of their origin (referred to as reports in the SPECI code form or SPECIs) are dealt with in 2.4 and 2.5, respectively. Practices relating to the transmission of local reports by local ATS units to aircraft taking off and landing are dealt with in 2.6. 2.3.2 The METAR and SPECI code forms were developed by WMO on the basis of aeronautical requirements established by ICAO. These codes were developed using the ICAO Procedures for Air Navigation Services ICAO Abbreviations and Codes (PANS-ABC, Doc 8400). In view of this, the METARs and SPECIs are easily readable. Note 1.- A tabulation developed by WMO to assist aeronautical personnel in the decoding of METAR and SPECI messages is reproduced in Appendix 3. Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Note 2.- All details relating to the METAR and SPECI code forms are contained in WMO Publication No. 306 Manual on Codes, Volume I, Part A - Alphanumerical Codes. f Note 3.- Units o measurement difer in some States depending on national practices. In this manual, all units used are those prescribed by ICAO Annex 5 - Units of Measurement to be Used in Air and Ground Operations as primary or alternative units. As regar& elementsfor which either of these units is permitted, numerical criteria are given for both units, and examples of reports are given in one or the other unit. Note 4.- The approved ICAO abbreviations which are to be used in “abbreviatedplain language” are given in the Procedures for Air Navigation Services - ICAO Abbreviations and Codes (Doc 8400). Note 5.- Details concerning regional diferences in aerodrome reports and concerning requirements for the exchange of these reports between meteorological offices can be found in the ICAO air navigation plan publications for the various ICAO regions. Note 6.- Selected criteria applicable to meteorological information referred to in 2.3.7 to 2.3.15 for inclusion in aerodrome reports are given in tabularform in Appendix 4. Not for Resale
  14. 14. Chapter 2. Meteorological Observations and Reports 2-3 2.3.4 m p e of report (MET REPORT) - MET REPORT (METAR) - METAR 2.3.5 Aerodrome identification (YUDO) in both reports ICA0 four-letter location indicator for the aerodrome for which the report is made. (The full name of the aerodrome is used in the transmission to aircraft.) Note.- The indicators are prescribed in Doc 7910 Location Indicators. 2.3.6 Time (22 16302) in both reports Date and time of observation: day of the month and time in hours and minutes, in Coordinated Universal Time (UTC). correspondingly reduced. A marked discontinuity occurs when there is an abrupt and sustained change in wind direction of 30” or more, with a wind speed of 20 lan/h (10 kt) before or after the change, or a change in wind speed of 20 kmh (i0 M) or more, lasting at least 2 minutes. The provision in 2.3.7.1 requires that the wind direction be reported by three figures, e.g. 030 or 240. The wind speed is reported by two (or three) figures, e.g. 05 or 15, supplemented by the units used (KMH or KT). (For further details, see 2.3.8.3 and 2.3.8.5). Calm conditions are reported as 00000. 2.3.8 Variations of wind (Table 2-1) 2.3.8.1 Variations of wind direction and speed given in meteorological reports always refer to the 10-minute period preceding the observation. When the wind is gusty, with variations from the mean wind speed (gusts) exceeding 20 kmh (10 kt), speed variations are indicated. 2.3.8.2 In local reports, when the wind direction varies by 60 degrees or more and when: 2.3.7 Wind directionlspeed (WIND 240/18KMH) - MET REPORT (24015KMH) - METAR a) the mean speed exceeds 6 km/h (3 kt) and the wind direction varies by less than 180 degrees: Note I.- Wind direction reported to aircraft for landing or take-off purposes must be converted into degrees magnetic. This conversion is normaliy carried out by the ATS unit concerned. Note 2.- For wind speed, either kilometres per hour or knots may be used. report the two extreme directions between which the wind has varied in degrees, after indication of the mean wind direction and speed, for example “WIND 010/9KT VRB BTN 3501 AND 050r’ (mean surface wind direction 10 degrees; wind speed 9 knots; wind direction variable between 350 degrees and 050 degrees); --`,,```,,,,````-`-`,,`,,`,`,,`--- 2.3.7.1 Direction (true) from which surface wind is blowing, in degrees rounded off to the nearest 10 degrees. The unit used for wind speed should be indicated both in local reports and METARs. In local reports, the term “CALM’ is used when a wind speed of less than 2 kmh (1 kt) is observed. Wind speed of 200 km/h (100 kt) or more is to be indicated as ABV199KMH or ABV99KT. b) the wind direction vanes by 180 degrees or more or where it is not possible to report a mean wind direction (e.g. when a thunderstorm passes over the aerodrome): 2.3.7.2 In reports disseminated locally at the aerodrome, surface wind should be based on an averaging period of 2 minutes. indicate the wind direction by the term “variable” (VRB) followed by the mean speed, with no indication of the mean wind direction, e.g. “WIND VRB 6KMH” or “VRB 3KT”. 2.3.7.3 In reports in the METAR code form, surface wind should be based on an averaging period of 10 minutes, except that when the 10-minute period includes a marked discontinuity in the wind direction andor speed, only data occurring since the discontinuity should be used for obtaining mean values, and the time interval should be 2.3.8.3 In reports in the METAR code form disseminated beyond the aerodrome, the variations from the mean wind direction are reported when the total variation is 60 degrees or more but less than 180 degrees and mean speed t. is above 6 kmh (3 k) In these conditions, mean wind direction and speed data (10-minute means) are followed Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale
  15. 15. Manual of Aeronautical Meteorological Practice 2-4 Table 2-1. Reporting procedures related to directional variations of wind. ddd = mean wind direction, dddl and ddd, = extreme wind directions, = Iddd, - ddd,l, W = mean wind speed. Averaging period applied indicated as a subscript. V = indicators of variability. Directional variations during past 1O minutes A Type of repori A s 60" ddd"J2 min Report in the METAR code form dddWlo min W 5 6 kmlh (3 kt) [but W > 2 kmlh (1 kt)]' W > 6 kmlh (3 kt) A Report disseminated locally at the aerodrome 60" 180" ddd"f2 min VRB BTN dddjl AND ddd2l A ? 180" A 180" ddd"N2 min VRB BTN dddll AND ddd2NV2 min VRBNV2 A 2 180' VRBNV2 dddW10 min by extreme direction values (reported clockwise) in a separate group. VRB is reported when the mean wind speed t is 6 km/h (3 k ) and less. A variable wind at higher wind speeds is reported when the variation in wind direction is 180 degrees and more or when it is impossible to determine a mean wind direction (e.g. when a thunderstorm passes over the aerodrome). 2.3.8.4 In reports disseminated locally at the aerodrome, speed variations are given as the maximum and minimum values of the wind speed attained, after indication of the mean wind direction and speed, in the form "WIND 180/40KMH MAX 70 MNM 20" or "WIND 180/ 20KT MAX 35 MNM 10". See Table 2-2. VRBW,, min VRBW,, VRBW,, respectively. Positions of wind sensors along individual runways should be indicated together with the reported wind data by the sections of the runway for which the wind data are to be representative. When wind observations are available from more than one runway in use, the indication of the relevant runway should also be attached to the reported wind data. Surface wind observations included in the METAñs should be representative of the whole runway complex at the aerodrome. 2.3.9 Visibility (VIS 600M) - MET REPORT (0600) - METAR 2.3.8.5 In reports in the METAR code form, speed variations shall be given as the maximum value attained, after indication of the mean wind direction and speed and preceded by the letter indicator G (for gusts); the minimum wind speed is never included (see Table 2-2). For wind speed of 100 units or more, the exact number of wind speed units is reported (e.g. 120KMH). When a wind speed is 200 km/h (100 kt) or more, the wind speed is reported as P199KMH (P99KT). Note 1. - Ksibility may be observed by a human observer or assessed by instrumented means. Thefollowing definition for Visibilityfor aeronautical purposes applies: 2.3.8.6 Wind observations in local reports used for arriving or departing aircraft should be representative for the touchdown zone and the conditions along the runway, b) the greatest distance at which lights in the vicinity of I O00 candelas can be seen and identified against an unlit background. Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS visibility for aeronautical purposes is the greater 0 8 a) the greatest distance at which a black object of suitable dimensions, situated near the ground, can be seen and recognized when observed against a bright background; Not for Resale --`,,```,,,,````-`-`,,`,,`,`,,`--- dddlVddd:
  16. 16. Chapter 2. Meteorological Observations and Reports 2-5 A > 20 krnlh (10 kt) A 5 20 kmlh (10 kt) I Report disseminated locally at the aerodrome I dddNV2 min I dddNV2 min MAX Wm, MNM W m n m 1 Report in the METAR code form Note 2.- The two distances have different values in air b of a given extinction coefticient, and the latter ( ) varies with the background illumination. The former (a) is represented by the meteorological optical range (MOR). Note 3.- Guidance on the conversion of instrumented readings into visibiliv is given in Annex 3, Attachment D. Note 4.- Transmissometers and/or forward-scatters metres should be used as sensors in instrumented systems for the assessment of visibiliv. 2.3.9.4 In reports in the METAR code form, visibility observations should be representative of the aerodrome and its immediate vicinity. In such observations, special attention should be paid to significant directional variations in visibility. When the visibility is not the same in different directions, the rules given in Table 2-3 apply. The reporting steps given in 2.3.9.1 apply also to the visibility values included in these reports. Visibility observations in metres are reported by four figures, e.g. 0200, 1500, 4000. When visibility is 10 km and above and the conditions for the use of CAVOK do not apply, visibility is indicated as 9999. --`,,```,,,,````-`-`,,`,,`,`,,`--- 2.3.9.1 Visibility is reported in steps of 50 m, e.g. VIS 350M, when visibility i s less than 800 m; steps of 100 m, e.g. VIS 600M, when visibility is 800 m or more, but less than 5 km, in steps of one kilometre, e.g. VIS 6KM, when visibility is 5 km or more, but less than 10 km. When visibility is 10 km or more, it is given as VIS lOKM, except when the conditions for the use of CAVOK apply. Note.- For the definition of CAVOK, see the Note under 2.3.12.2. Note.- The conditions governing the use of CAVOK are summarized in the Note under 2.3.12.2 below. b) in reports for arriving aircraft, the visibility observations should be representative of the approach and landing area. 2.3.10.1 RVR should be reported whenever visibility or runway visual range (RVR) is less than 1 500m, particularly at aerodromes having precision approach runways or runways used for take-off with high-intensity edge lights andíor centre line lights, including the aerodromes with the runways intended for Category I approach and landing operations. RVR is reported at all runways intended for Category II or III instrument approach and landing operations. Steps of 25 m are used for RVR below 400 m, steps of 50 m for RVR between 400 m and 800 m and steps of 100 m for RVR above 800 m. RVR values which do not fit the reporting scale are rounded down to the next lower step in the scale. 2.3.9.3 In local reports, when the visibility is observed for more than one runway in use and at more than one location along the runway, the identification of relevant runways and locations along the runways should be attached to the reported values of visibility. 2.3.10.2 In reports disseminated locally at the aerodrome, 1-minute mean values are reported. The RVR is reported in metres with an indication of the unit, and the runway(s) to which the values refer, e.g. RVR RWY 20 500M RVR RWY 26 800M (RVR runway 20: 500 m, RVR 2.3.9.2 drome: In reports disseminated locally at the aero- a) in reports for departing aircraft, the visibility observations should be representative of the takeoff and climb-out area; and Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS 2.3.10 Runway visual range (RVR RWY 12 1000M) - MET REPORT (Rl2/lOOOU) - METAR Not for Resale
  17. 17. Manual o Aeronautical Meteorological Practice f 2-6 Table 2-3. Reporting procedures related to visibility - to be applied in reports in the METAR code form Conditions Action VIS not the same in different directions, no marked directional variations Report the lowest VIS VIS in one or more directions is more than 50 per cent above the lowest VIS and the minimum value 5 O00 m Report the lowest VIS together with its general direction from the meteorological station. Example: “1200s” Lowest VIS observed in more than one direction Report the lowest VIS in the most operationally significant direction. Example: “0500” Lowest VIS in one direction <I m, and VIS in another 500 direction >5 O00 m Report both VIS values and directions Example: “1100E 7000W If the highest visibility i observed in more than one s direction, the most operationally significant direction should be reported VIS fluctuating rapidly; directional variations cannot be given Report lowest VIS without indication of direction Note.- Direction is to be reported by reference to one of the 8 points of the compass. runway 26: 800 m). If RVR is observed for more than one position along a runway, the value representative of the touchdown zone is given first, followed by the locations representative of the mid-point and stop-end, e.g. RVR RWY 16 TDZ 600M MID 500M END: 400M (RVR runway 16 at the touchdown zone: 600 m, at the mid-point: 500 m and at the stop-end: 400 m). When RVR is above the maximum value that can be determined by the system in use, it is reported in the form RVR ABV 1200M where 1 200 m is the maximum value for that system. When RVR is below the minimum value that can be determined by the system in use, it is reported in the form RVR BLW 150M, where 150 m is the minimum value for that system. For assessment of RVR, 50 m is considered the lower limit and 1 500 m the upper limit. Outside these limits, reports merely indicate that the RVR is less than 50 m or more than 1 500 m, in the form RVR BLW SOM (RVR below 50metres) or RVR ABV 1500M (RVR above 1 500 metres), respectively. 2.3.10.3 The provisions given in 2.3.10.1 also apply to reports in the METAR code form. In these reports, RVR values in metres are reported by four figures preceded by the letter indicator R and the runway designator DRDR plus / (e.g. R12/0500, R26í1200). Additional reporting pro- . cedures are given in Table 2-4. Note 1.- A n RVR observation is the best possible f f assessment o the range over which the pilot o an aircraft on the centre line o a runway can see the runway suface f markings or the lights delineating the runway or identifjting ifs centre line. For this assessment, a height o approxif mately 5 m (15 ft) is regarded as corresponding to the average eye level of a pilot in an aircraft. This assessment f may be based on readings o transmissometers or fonvardscatter meters or may be determined by an observer counting markers, runway lights or, in some cases, specially f installed lights on the side o the runway. Note 2.- Detailed information on RVR observing and reporting is contained in the ICA0 Manual of Runway Visual Range Observing and Reporting Practices (Doc 9328). 2.3.11 Present weather (FG MOD DZ) - MET REPORT (FZ DZ) - METAR 2.3.11.1 Present weather phenomena are reported in terms of type and characteristics and are qualified with respect to intensity or proximity to the aerodrome, as appropriate. 2.3.11.2 The types of present weather phenomena of significance to aviation, their respective abbreviations and relevant criteria for their reporting are given in Table 2-5. 2.3.1 1.3 The characteristics of the present weather phenomena that are reported, as necessary, and their respective abbreviations are given in Table 2-6. 2.3.11.4 The relevant intensity and, as appropriate, the proximity to the aerodrome of the reported present weather phenomena are indicated in Table 2-7. --`,,```,,,,````-`-`,,`,,`,`,,`--- Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale
  18. 18. Chapter 2. Meteorological Observations and Reports 2- 7 Table 2-4. Additional reporting procedures related to RVR data in reports in the METAR code form Reporting procedure More than one runway in use Include all such runways up to a maximum of four. RVR values from parallel runways can be included in a report by attaching "L, C, R letter (L = left, C = centre, R = right to the runway designator D,D,) Section of the runway Only the value representative of the touchdown zone is given, without indication of position. RVR information determined using instruments Report of the mean value during the IO-minute period immediately preceding the observation When RVR is greater than the maximum value which can be determined by the system in use Report the highest value which can be determined by the system preceded by the letter indicator P When RVR is below the minimum value which can be determined by the system in use Report the lowest value which can be determined by the system preceded by the letter indicator M When RVR is more than 1 500 m (less than 50 m) Report 1500 preceded by the letter indicator P, (0050 preceded by the letter indicator M) RVR variations in time If the I-minute extreme RVR values during the IO-minute period immediately preceding the observation vary from the mean value by more than 50 m or more than 20 per cent of the mean value, whichever is greater, the I-minute mean minimum and the I-minute mean maximum values should be reported instead of the IO-minute mean value, in the form "R09/0350V0600". (The letter indicator V is included between the maximum and minimum values.) Discontinuities in RVR values If the IO-minute period immediately preceding the observation includes a marked discontinuity in RVR values, only those values occurring after the discontinuity should be used to obtain mean values and variations. A marked discontinuity occurs when there is an abrupt and sustained change in RVR, lasting at least 2 minutes, which reaches or passes the criteria for the issuance of selected special reports given in 2.5.1 9. Tendency in RVR values --`,,```,,,,````-`-`,,`,,`,`,,`--- Condition If the RVR values during the IO-minute period have shown a distinct tendency, such that the mean value during the first 5 minutes varies by 100 m or more from the mean value during the second 5 minutes of the period, this should be indicated as follows: a) when the variation of the RVR values shows an upward or downward tendency, this should be indicated by the indicator "U" or "D", respectively, in the form "R12/1000U", appended to relevant RVR values; b) when actual fluctuations during the 1O-minute period indicate no distinct tendency, this should be reported using the indicator "N"; c) when indications of tendency are not available, none of the foregoing indicators should be included. Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale
  19. 19. Manual o Aeronautical Meteorological Practice f 2-8 ~~ Table 2-5. Types of present weather phenomena Type Phenomenon Precipitation Drizzle DZ Rain RA Snow SN Snow grains SG Ice pellets PL Ice crystals (very small ice crystals in suspension, also known as diamond dust) IC Reported only when associated visibility is 5 O00 m or less Hail GR Small hail andlor snow pellets GS Reported when diameter of largest hailstones is 5 mm or more Reported when diameter of largest hailstones is less than 5 rnm Fog FG Mist BR Obscurations (lithometeors) Sand Dust (widespread) Haze Smoke Volcanic ash SA DU HZ FU VA Other phenomena Dustlsand whirls (dust devils) Squall Funnel cloud Duststorm Sandstorm PO Obscurations (hydrometeors) 1. Abbreviation' SQ FC DS ss Used in both local reports and reports in the METAR code form. --`,,```,,,,````-`-`,,`,,`,`,,`--- Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale Remarks Reported when visibility is less than 1 O00 rn, except when qualified by "MI", "BC", "PR" or "VC" Reported when visibility is at least 1 O00 m but not more than 5 O00 m Used only when the obscuration consists predominantly of lithometeros and the visibility is 5 O00 rn or less except "SA" when and volcanic ash qualified by "DR" Tornado or waterspout
  20. 20. Chapter 2. Meteorological Observations and Reports 2-9 Table 2-6. Characteristics of present weather phenomena Abbreviation' Remarks Thunderstorm TS Used to report a thunderstorm with rain "TSRA", snow 'TSSN", ice pellets "TSPE", hail "TSGR" or small hail andlor snow pellets "TSGS" or combinations thereof, for example, "TSRASN". When thunder is heard during the IO-minute period preceding the time of observation but not precipitation is observed at the aerodrome, the abbreviation "TS" should be used without qualification. Shower SH Used to report showers of rain "SHRA", snow "SHSN", ice pellets 'SHPE", hail "SHGR", small hail andior snow pellets 'SHGS", or cornbinations thereof, for example, 'SHRASN". Showers observed in the vicinity of the aerodrome should be reported as "VC SH" without qualification regarding type or intensity of precipitation. Freezing FZ Supercooled water droplets or precipitation, used only with FG, DZ and RA. Blowing BL Used to report DU, SA or SN (including snowstorm) raised by the wind to a height of 2 m (6 ft) or more above the ground; in the case of snow, also used to report snow falling from a cloud and mixed with snow raised by the wind from the ground. Low drifting DR Used with SA, DU or SN raised by the wind to less than 2 m (6 ft) above ground level. Shallow MI Less than 2 m (6 ft) above ground level. Patches BC Fog patches randomly covering the aerodrome. Partial PR A substantial part of the aerodrome covered by fog while the remainder is clear. 1. Used in both local reports and reports in the METAR code form. Table 2-7. Intensity/proximity of present weather phenomena Local abbreviated plain language reports Reporis in the METAR code form Light FBL - Moderate MOD (no indication) Heavy used only with: precipitation; SH and TS (in these cases,intensity refers to precipitation); BLSN; BLSA; BLDU; DS; SS; and PO, FC (in these cases, HVY means well developed) HVY + Vicinity not at the aerodrome but not further away than approximately 8 km from the aerodrome perimeter and used only with DS, SS, FG, FC. SH, PO, BLDU, BLSA, BLSN and TS when not reported under the characteristics of the present weather phenomena vc vc Intensity/pmximity Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale --`,,```,,,,````-`-`,,`,,`,`,,`--- Characteristics
  21. 21. Manual o Aeronautical Meteorological Practice f 2-10 an indication of intensity or proximity, as appropriate, should be reported first; this is followed by both the characteristics and the type of weather phenomena in the form “HVY TSRA” or “VC FG”; where two different types of weather are observed, they should be reported in two separate groups, in the form “HVY DZ F G or “FBL DZ VC FG’, where the intensity or proximity indicator refers to the weather phenomenon which follows the indicator; and different types of precipitation occurring at the time of observation should be reported as one single group with the dominant type of precipitation reported first, preceded by only one intensity qualifier which refers to the intensity of the total precipitation, in the form “HVY TSRASN’ or “FBL SNRA FG”. - the lowest layer or mass, regardless of amount, reported as FEW, SCT, BKN or OVC, as appropriate; - the next layer or mass, covering more than 2/8*, reported as SCT, BKN or OVC, as appropriate; - the next higher layer or mass, covering more than 4/8*, reported as BKN or OVC as appropriate; and - cumulonimbus (CB) andor towering cumulus (TCU) clouds, whenever observed and not reported in previous parts of the report. Note.- Towering cumulus (TCU) is used to indicate f cumulus congestus clouds o great vertical extent. 2.3.12.2 when an individual layer (mass) of cloud is composed of cumulonimbus and towering cumulus clouds with a common cloud base, the type of cloud is reported as cumulonimbus only. if no clouds are present, and there is no restriction on vertical visibility and the term CAVOK (see the Note below) is not appropriate, the term SKC (sky clear) is used. Note.- The term CAVOK2 is used when the following visibility/cloudweather conditions occur simultaneously: - Visibiliîy: I O km or more. - Cloud: No cloud below 1 500 m (5 OOOfi) or below 2.3.11.6 When local reports are used for departing and arriving aircraft, the present weather observations should be representative of the take-ofüclimb-out areas or the approach/landing areas, respectively. Observations of present weather in the METAR reports should be representative of the aerodrome and its vicinity. 2.3.12 Cloud (CLD SCT 300M OVC 600M) - MET REPORT (SCTOlO OVC020) - METAR 2.3.12.1 Cloud amount is given using the abbreviations FEW (1-2 oktas)’, SCT (3-4 oktas)’, BKN (5-7 oktas)’ or OVC (8 oktas)’. The type of cloud is identified only for cumulonimbus and towering cumulus clouds when observed at or near the aerodrome. Cloud amount, cloud type (CB and TCU only) and height of cloud base above aerodrome elevation are reported in that order and in the sequence shown: 1. Eighths of the sky. Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS the highest minimum sector altitude, whichever i s greatec and no cumulonimbus. - Weather: No weather o signifzcance to aviation as f given in Tables 2-5 and 2-6. 2.3.12.3 If no clouds of operational significance are present, i.e. below 1 500 m (5 O00 fi) or below the highest minimum sector altitude, whichever is greater, no cumulonimbus occur and no restriction on vertical visibility exists and the abbreviation “CAVOK” and “SKC“ cannot be used, the abbreviation “NSC” (i.e. nil significant clouds) should be used. 2.3.12.4 In local reports, the height of the base of cloud is reported in steps of 30 m (100 fi) up to 3 O00 m (10 O00 fi), together with the units used, in the’ form “300M’ or “lOOOFT”, and in steps of 300 m (1 O00 ft) above 3 O00 m (10 O00 fi). When the cloud base is diffuse or ragged or fluctuating rapidly, the minimum height of the 2. Pronounced KAV-ûH-KAY. Not for Resale --`,,```,,,,````-`-`,,`,,`,`,,`--- 2.3.11.5 One or more (up to a maximum of three) of the present weather abbreviations given in Tables 2-5 and 2-6 should be used, as necessary, together with an indication, where appropriate, of the characteristics and intensity or proximity to the aerodrome, so as to convey a complete description of the present weather at or near the aerodrome of significance to flight operations. The following general rules apply:
  22. 22. Chapter 2. Meteorological Observations and Reports 2-11 cloud, or cloud fragments, is given, followed by the relevant abbreviation DIF (diffuse) or RAG (ragged) or FLUC (fluctuating). Note 1.- In reports for arriving aircrafi, where a precision approach runway has a touchdown elevation of 15 m (50 fi) or more below the aerodrome elevation, arrangements are normally made for cloud height to be given with reference to the touchdown elevation. Note 2.- In reports from offshore structures, the height of the base of cloud is given above mean sea level. 2.3.12.5 The provisions given in 2.3.12.1 and 2.3.12.2 apply also to cloud observations reported in the METAR messages where relevant abbreviations for cloud amount (i.e. FEW, SCT, BKN or OVC) are followed by three figures indicating the reported cloud height in steps of 30 m (100 fi) (e.g. 005, 020) up to 3 O00 m (10 O00 fi) and in steps of 300 m (1 O00 ft) above 3 O00 m (1O O00 ft). Up to three groups plus an additional group reporting CB andlor TCU could be included in one report. The note under 2.3.12.2 applies to the use of CAVOK. 2.3.12.6 When the sky is obscured and observations of vertical visibility are available at the aerodrome, the abbreviations VER VIS (vertical visibility) are used, followed by the value of the vertical visibility and the units used. The reporting steps for vertical visibility are the same as those used for reporting the height of the cloud base. In the METAR messages, the vertical visibility value is reported in the same manner as the cloud height described in 2.3.12.4, preceded by the letter indicator VV. Wll/ indicates the absence of vertical visibility data. --`,,```,,,,````-`-`,,`,,`,`,,`--- 2.3.12.7 Cloud observations included in local reports should be representative of the approach area or in the case of precision approach runways, of the middle marker site of the instrument landing system. Cloud observations in reports in the METAR code form should be representative of the aerodrome and its vicinity. higher whole degree Celsius, for example, +2.5"C is rounded off to +3"C and -2.5"C is rounded off to -2°C. In local reports, the air temperature is identified by T and the dew point temperature by DP in the form TI7 DP16 (temperature 17, dew point 16). For a temperature below Odegrees Celsius, the value is preceded by MS (minus), e.g. TMSS. 2.3.13.2 Air temperature and dew point temperature values are reported in reports in the METAR code form in the form of T'T'/Td'Td'. Temperatures below 0°C are preceded by M meaning minus. In addition, air temperatures and dew point temperatures of -9°C to +9"C are preceded by O, e.g 02MOS. 2.3.13.3 Observations of air temperature and dew point temperature should be representative of the whole runway complex. 2.3.14 Pressure values (QNH 1O 18 HPA) - MET REPORT (QlOlS) - METAR 2.3.14.1 In local reports, pressure values are given in hectopascals and are identified by QNH (altimeter showing aerodrome elevation when the aircraft is on the ground and QNH is set on the altimeter sub-scale) or QFE (altimeter showing zero elevation when the aircraft is on the ground and QFE is set on the altimeter sub-scale). QFE is normally used only at the aerodrome where it is provided on request or, by local agreement, on a regular basis, in addition to QNH. Pressure values are rounded down to the nearest lower whole hectopascal, e.g. QNH 1011.4 is reported as QNH lO11HPA and QFE 995.6 is reported as QFE 0995HPA or QFE RWY 18 0995HPA (where the number of the runway is indicated). Note.- When a QFE altimeter setting is provided, it corresponds to the aerodrome elevation except for: 2.3.12.8 Where local reports include cloud base data from more than one runway in use, the runway indication should be attached to the reported cloud base data. a) non-precision approach runways, ifthe threshold is 2 m (6.63)or more below the aerodrome elevation; and b) precision approach runways, 2.3.13 Air temperatureldew point temperature (T17 DP16) - MET REPORT (17/16) - METAR in which cases, the QFE corresponds to the relevant runway threshold elevation. 2.3.13.1 Reported in whole degrees Celsius, with observed values involving 0.5" rounded up to the next Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS 2.3.14.2 QNH values specified in 2.3.12.1 are presented in METAR messages by four figures (e.g. 0995 or 1011) following the letter indicator Q. Not for Resale
  23. 23. Manual of Aeronautical Meteorological Practice 2-12 2.3.15 Supplementary information 2.3.15.1 Local reports may also include available supplementary information on significant meteorological conditions, particularly those in the approach or climb-out area and, specifically, the location of cumulonimbus, thunderstorms, presence of wind shear, moderate or severe turbulence, hail, severe squall line, moderate or severe icing, freezing precipitation, severe mountain waves, sandstorm, duststorm and blowing snow or funnel cloud (tomado or waterspout). The abbreviations in Table 2-8 a) should be used in reporting this supplementary information. Also included are any of the weather phenomena listed in Table 2-8 b) or combinations thereof, if observed at the aerodrome within the period since the last issued routine report or last hour, whichever is the shorter, but not at the time of observation (recent weather of significance). Up to a maximum of three groups of the recent weather should be reported. --`,,```,,,,````-`-`,,`,,`,`,,`--- Note.- Observations of supplementary information, in particular the conditions relating to the occurrence of icing, turbulence and, to a large extent, of wind shear, should be derived from aircraft observations during the approach and climb-out phases ofjlights. (For details concerning aircraft observations and air-reports, see Chapter 4.) 2.3.15.2 In reports in the METAR code form, supplementary information includes information on recent weather of operational significance, as given in 2.3.15.1, observed at the aerodrome within the period since the last issued routine report or last hour, whichever is the shorter, but not at the, time of observation. Where local circumstances so warrant, wind shear should be included as necessary. Up to three groups of recent significant weather information selected from the following list may be included in a report using suitable abbreviations from Tables 2-5 and 2-6: - freezing precipitation - moderate or heavy precipitation (including showers thereof) - moderate or heavy blowing snow (including snow- information on recent significant weather is to be added in the form, for example, “REFZRA”. Information on wind shear is added, if necessary, in the form “WS RWY 12” or “WS ALL RWY”. Information on sea-surface temperature and the state of the sea is included in reports from aeronautical meteorological stations established on offshore structures in support of helicopter operations, as determined by regional air navigation agreement. Information on the state of the runway(s) may also appear in these reports in accordance with regional air navigation agreement. The same applies to other information to be added to the METAR messages intended for international use . Note 1.- The “local circumstances” referred to above include, but are not necessarily limited to, wind shear of a non-transitory nature such as might be associated with lowlevel temperature inversions or local topography. Note 2.- Warnings of wind shear in the climb-out and approach paths are detailed in Chapter 4. Note 3.- The state of the sea is specijìed in WMO Publication No. 306, Manual on Codes, Volume I, Code Table 3700. 2.3.16 Landing forecasts A trend forecast is often attached to a local routine report as well as a routine report in the METAR code form; together they constitute a “trend-type” landing forecast, details of which are given in Chapter 3 and Appendix 2. 2.4 LOCAL SPECIAL REPORTS 2.4.1 Local special reports are issued in abbreviated plain language in addition to local routine reports (see 2.3 above) to provide information on significant deteriorations or improvements in aerodrome weather conditions at the aerodrome concerned. They are issued whenever one or more elements of a routine report change in accordance with criteria established by the meteorological authority in consultation with the ATS authority, the operators and others concerned. These criteria include: storm) - duststorm or sandstorm - thunderstorm a) those values which correspond with the operating minima of the operators using the aerodrome; b) those values which satis@ other local requirements of ATS units and of the operators; - funnel cloud (tomado or water spout) - volcanic ash Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS c) an increase in air temperature of 2°C or more from that given in the latest report, or an alternative Not for Resale
  24. 24. Chapter 2. Meteorological Observations and Reports 2-13 Table 2-8. Supplementary information for inclusion in local routine and special reports a) Significant weather conditions Abbreviations ConditiondDecode CB TS MOD TURB SEV TURB Cumulonimbus Thunderstorm Moderate turbulence Severe turbulence Wind shear Hail Severe squall line Moderate icing Freezing drizzle Freezing rain Severe mountain wave Sandstorm Duststorm Blowing snow Funnel cloud (tornado or waterspout) In the approach In the climb-out In cloud ws GR SEV SQL MOD ICE FZDZ FZRA SEV MTW ss DS BLSN FC IN APPCH IN CLIMB-OUT INC Note.- Additional information may be included using abbreviated plain language. b) Abbreviations and decodes to be used in reporting recent significant weather Abbreviations ConditiondDecode REFZDZ REFZRA REDZ RERA RESN RESG REGR REGS REPL RESHRA RESHSN RESHSG RESHPL RESHGR RESHGS REIC REBLSN RESS REDS RETS REFC REVA Recent freezing drizzle Recent freezing rain Recent drizzle Recent rain Recent snow Recent snow grain Recent hail Recent small hail and/or snow pellets Recent ice pellets Recent rain showers Recent snow showers Recent showers of snow grains Recent showers of ice pellets Recent showers of hail Recent showers of small hail andlor snow pellets Recent ice crystals Recent blowing snow Recent sandstorm Recent duststorm Recent thunderstorm Recent funnel cloud (tornado or waterspout) Recent volcanic ash - --`,,```,,,,````-`-`,,`,,`,`,,`--- Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale
  25. 25. Manual of Aeronautical Meteorological Practice 2-14 threshold value as agreed upon between the meteorological authority, the appropriate ATS authority and the operators concerned; tent and sequence of elements as local routine reports (2.3.4 to 2.3.15 refer). As with local routine reports, a trend forecast is often appended to the special report (see 2.3.16 above). d) the available supplementary information conceming the occurrence of significant meteorological conditions in the approach and climb-out areas; and e) the criteria given below (2.5.1 refers) for the issuance of special reports in the SPECI code form disseminated beyond the aerodrome (Le. aviation selected special weather reports referred to in the WMO Publication No. 306, Manual on Codes, Volume 1.1, Part A under FM 16-XII SPECI code form). 2.5 SPECIAL REPORTS IN THE SPECI CODE FORM 2.5.1 Special reports in the SPECI code form are issued in accordance with the following criteria: a) when the mean surface wind direction has changed by 60 degrees or more from that given in the latest report, the mean speed before andor after the change being 20 ladh (or 10 kt) or more; Local special reports in respect of RVR, surface wind or some other elements are not normally issued if the local ATS unit(s) has indicators for these elements corresponding to the indicators in the meteorological station, or if changes in RVR are continuously reported to the ATS unit by an observer at the aerodrome. Displays of automated aerodrome meteorological observing stations/systems located at the local ATS units are widely used to meet this requirement. b) when the mean surface wind speed has changed by 20 ladh (or 10 kt) or more from that given in the latest report; c) when the variation from the mean surface wind speed (gusts) has increased by 20 ladh (or 10 kt) or more from that given in the latest report, the mean speed before andor after the change being 30 km/h (or 15 kt) or more; 2.4.2 Local special reports carry the identifier SPECIAL and, as Example 2-2 shows, have the same con- Example 2-2. Special reports a) Local special reports disseminated locally at the aerodrome: SPECIAL YUDO* 151115Z WIND 050/26KT MAX37 MNMIO VIS 1000M RWY12 RVR 1200M HVY TSRA CLD BKN CB 500FT T25 DP 22 QNH 1008HPA b) Special report in the SPECI code form disseminated beyond the aerodrome: SPECI YUDO' 151115Z 05025G37KT 1000NE 6000s R12/1200N +TSRA BKNOOSCB 25/22 QI008 Meaning of both reports: Local special report or special report in the SPECI code form for Donlonllnternational" issued on the 15th of the month at 1115 UTC; surface wind direction 050 degrees; wind speed 26 or 25 knots (averaged over 2 or 10 minutes, respectively) gusting between 1O and 37 knots (for reports disseminated beyond the aerodrome: "gusting to 37 knots"); visibility 1 O00 metres only (only for reports disseminated beyond the aerodrome: visibility lowest to northeast 1 O00 metres, visibility 6 O00 metres to south"); runway visual range representative for the touchdown zone for runway 12, 1 200 metres (averaged over 1 and 10 minutes, respectively), (for reports disseminated beyond the aerodromes: "no distinct tendency detected" in runway visual range values during previous 10 minutes); thunderstorm with heavy rain; broken cumulonimbus cloud at 500 feet; air temperature 25 degrees Celsius; dew point temperature 22 degrees Celsius; QNH 1008 hectopascals. * Fictitious location --`,,```,,,,````-`-`,,`,,`,`,,`--- Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale
  26. 26. Chapter 2. Meteorological Observations and Reports 2-15 when the wind changes through values of operational significance. The threshold values should be established by the meteorological authority in consultation with the appropriate ATS authority and operators concerned, taking into account changes in the wind which would: 1) 30 m, 60 m, i50 m or 300 m (100 ft, 200 ft, 500 ft or i O00 ft); 2) 450 m (1 500 fi), in cases where significant numbers of flights are operated in accordance with visual flight rules; when the amount of a cloud layer below 450m (1 500 ft) changes: i) require a change in runway(s) in use; and 2) indicate that the runway tailwind and crosswind components have changed through values representing the main operating limits for typical aircraft operating at the aerodrome. 1) from SKC, FEW or SCT to BKN or OVC; or 2) from BKN or OVC to SKC, FEW or SCT; when the sky is obscured and the vertical visibility is improving and changes to, or passes through, one or more of the values below; or when the sky is obscured and the vertical visibility is deteriorating and passes through one or more of the values below: when the visibility is improving and changes-to, or passes through, one or more of the values below; or when the visibility is deteriorating and passes through one or more of the values below: 1) 800 m, 1 500 m or 3 O00 m 2) 5 O00 m, in cases where significant numbers of flights are operated in accordance with visual flight rules; 150 m, 350 m, 600 m or 800 m; when the onset, cessation or change in intensiîy of any of the following weather phenomena or combinations thereof occurs: freezing precipitation freezing fog moderate or heavy precipitation (including showers thereof) low drifting dust, sand or snow blowing dust, sand or snow (including snowstorm) duststorm sandstorm thunderstorm (with or without precipitation) squall funnel cloud (tomado or waterspout). when the height of the base of the lowest cloud layer of BKN or OVC extent is lifting and changes to, or passes through, one or more of the values below; or when the height of the base of the lowest cloud layer of BKN or OVC extent is lowering and passes through one or more of the values below: Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS 500 f or i O00 It). t 2.5.2 Special reports in the SPECI code form carry the identifier SPECI and, as Example 2-2 shows, have the same content and sequence of elements as routine reports in the METAR code form (2.3.4 to 2.3.15 refer). As with reports in the METAR code form, a trend forecast is often appended to these reports (2.3.14). 2.5.3 Special reports in the SPECI code form are disseminated beyond the aerodrome of origin to other aerodromes in accordance with the regional air navigation agreement which ensures, inter alia, that the special reports are available for VOLMET broadcasts, for D-VOLMET, .and for individual transmissions to aircraft in flight through ATS units or operators . Note.- Details on requirements for the exchanges between meteorological ofices of special reports in the SPECI code form can be found in the ICAO air navigation plan publications for the various ICAO regions. 2.6 INFORMATION ON METEOROLOGICAL CONDITIONS FOR AIRCRAFT TAKING OFF AND LANDING Local routine and local special reports, as described in 2.3 and 2.4, are usually supplied to those ATS units which use them, together with any information obtained from their Not for Resale --`,,```,,,,````-`-`,,`,,`,`,,`--- when the RVR is improving and changes to, or passes through, one or more of the values below; or when the RVR is deteriorating and passes through one or more of the values below: - 30 m, 60 m, 150 m or 300m (100 ft, 200 ft,
  27. 27. Manual of Aeronautical Meteorological Practice own duplicate displays (e.g. wind or RVR indicators), displays of automated aerodrome weather observing stations or supplementary visual observations taken by ATS personnel, in order to provide the required meteorological information to aircraft taking off or landing. These reports are supplied to aircraft by ATS units by air-ground data link, by directed transmissions andor through broadcasts. Further details on coordination between meteorological officesistations and ATS units in this and other respects are given in Chapter 8. 2.9 AIRCRAFT OBSERVATIONS AND REPORTS (AIREP) --`,,```,,,,````-`-`,,`,,`,`,,`--- 2-16 Weather reports from aircraft constitute an important source of upper-air data. They are especially useful in areas where ground-based observations are sparse or not available. In view of its importance, air-reporting is covered further in Chapter 7 of this manual. 2.10 BASIC SURFACE AND UPPER-AIR OBSERVATIONS 2.7 REPRESENTATIVENESS AND ACCURACYAERODROME REPORTS To the extent practicable, aerodrome observations are made at locations considered to be suitable for representative measurements of elements affecting aircraft during take-off and landing operations. Details in respect of these locations and in respect of the aeronautical requirements for the operationally desirable accuracy of meteorological observations and the currently attainable accuracies are given in Appendix 5, Parts 1 and 2, respectively, to this manual. 2.8 WEATHER RADAR OBSERVATIONS AND REPORTS 2.8.1 Weather radar observations permit the locating and tracking of thunderstorms and tropical cyclones, and the evaluation of precipitation and cloud height. This information is used for early warnings of certain meteorological phenomena hazardous to aviation, particularly in the vicinity of aerodromes, and in the preparation of trend forecasts. Radar data are usually available only locally, but in many parts of the world, data from -large radar networks are distributed to meteorological offices and other aeronautical users by means of various data processing systems and high-speed communication channels in coded or pictorial forms and, in particular, in digital form. The processed and integrated weather radar information is often displayed for ATS personnel through ATS systems. 2.8.2 Increasing use is being made of Doppler weather radar for both storm warning purposes and, specifically, to detect low-level wind shear. In the latter case, fully automated terminal Doppler weather radar is available, which can provide wind shear warnings to ATC and directly to aircraft equipped with an air-ground data link. Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS 2 1 O. 1 Weather observations containing elements sim: ilar to those in aerodrome reports, but with additional details of cloud, weather, pressure, etc., are made at many aerodromes and other locations (including ships) for basic meteorological purposes. They are made at three-hourly or six-hourly intervals (O000 UTC, 0300 UTC, 0600 UTC, etc.), disseminated in a code form (SYNOP) established by WMO, and used for the preparation of surface weather charts. 2.10.2 Upper-air infomation is obtained principally f o instruments carried aloft by balloons released from rm fixed ground observation sites or from ships. These balloon-borne instruments reach altitudes approaching 30 km (100 O00 ft) and provide data on wind speed and direction, temperature, pressure and relative humidity to approximately 15 km (50 O00 ft). Upper-air observations of this type are made at standard hours, O000 UTC and 1200 UTC and additionally in some areas at 0600 UTC and 1800 UTC. Other upper-air information is obtained through specialized equipment carried on board certain aircraft. All these data are disseminated in code forms established by WMO, and are used for the preparation of upper-air charts. 2.11 METEOROLOGICAL SATELLITE DATA In addition to information on cloud type, amount and height of cloud tops, meteorological satellite data also provide information on vertical temperature and humidity distribution and on upper winds derived from cloud movement. The information provided by satellites is of particular importance in the areas where ground-based observations are sparse. It is received directly from geostationary or polar-orbiting satellites by ground-receiving equipment. The processed satellite data can be used to supplement the integrated weather radar data. Data f o geostationary rm meteorological satellites are also used by volcanic ash advisory centres for the detection and tracking of volcanic ash clouds. Not for Resale
  28. 28. 2-1 7 Chapter 2. Meteorological Observations and Reports 2.12 REPORTS OF VOLCANIC ACTIVITY As mentioned in 1.4.2, aeronautical meteorological stations (and other meteorological stations) located in the vicinity of active volcanoes are required to make observations of volcanic activity. The volcanic activity reports resulting from these observations should contain: a) message type VOLCANIC ACTIVITY REPORT; b) station identifier, location indicator or name of the station; c) datehime of the message; The reports should be issued in the form of abbreviated plain language and disseminated, as a matter of urgency, to the associated ATS units, meteorological watch offices, and aeronautical information services units. These reports are important for the operations of the International Airways Volcano Watch (IAVW). Note.- Pre-emption volcanic activis in this context means unusual and/or increasing volcanic activity which could presage a volcanic eruption. d) location of volcano, and name, if known; and --`,,```,,,,````-`-`,,`,,`,`,,`--- Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS e) concise description of the event including, as appropriate, the level of intensity of the volcanic activity, occurrence of the eruption and its date and time, and the existence of a volcanic ash cloud in the area together with the direction of the ash cloud movement and height. Not for Resale
  29. 29. Chapter 3 FORECASTS 3.1 GENERAL SIGMET and AIRMET information, aerodrome warnings and wind shear warnings may refer to existing as well as expected conditions. (For further details on SIGMET and AIRMET information, aerodrome warnings and wind shear warnings, see Chapter 4 of this manual.) Similarly, volcanic ash advisories containing information concerning location, extent and trajectories of volcanic ash clouak and tropical cyclone advisories containing information concerning tropical cyclones and their centres’ movement can also be considered as forecasts. Details concerning the advisories are given in Chapter 4. A forecast is a concise statement of expected meteorological conditions at an aerodrome or over an area or along a route. Owing to the variability of meteorological elements in space and time, the limitation of forecasting techniques, and the limitations caused by the definitions of some of the individual meteorological elements (e.g. surface wind, weather), the specific value of any forecast element is to be understood as being the most probable value which the element is likely to assume during the period of the forecast. Similarly, when the time of occurrence or change of.an element is given in a forecast, this is to be understood to be the most probable time. 3.3.2 Forecasts can also be divided in accordance with the formats in which they are normally issued (abbreviated plain language, code, tabular or graphic, i.e. chart form) as shown in Table 3-2. 3.2 ACCURACY OF AERONAUTICAL METEOROLOGICAL FORECASTS The accuracy of aeronautical forecasts depends upon the accuracy, spacing and frequency of available observations, the period of the forecast and various factors associated with analysis and forecasting techniques. In general, the forecast elements are the best estimate of the conditions expected to occur within a range of values. Guidance on the operationally desirable accuracy of aeronautical forecasts is contained in Appendix 6 . 3.4 AERODROME FORECASTS 3.3.1 There are different types of aeronautical forecasts designed to meet requirements for the various stages of flight planning. They differ in respect of area or airspace covered and in respect of the offices preparing and issuing them, as shown in Table 3- 1. 3.4.1 Aerodrome forecasts follow the general form of aerodrome weather reports in the METAR code form and should be always coded in the TAF code form. They include surface wind, visibility, forecasts of significant weather phenomena and cloud, and relevant significant changes thereto (see Example 3-1). Detailed technical specifications for aerodrome forecasts in the TAF code form are reproduced in Appendix 7. Table A7-1 in Appendix 7 includes an extensive set of examples relating to individual portions of the forecast. Aerodrome forecasts valid for 9 hours are normally issued every 3 hours and those valid for 12, 18 or 24 hours are normally issued at six-hourly intervals. The validity period of aerodrome forecasts is determined for each region on the basis of air navigation agreements. Note.- Whileforecasts generalb refer to the meteorological conditions expected to occur (i.e. in the future), 3.4.2 The specific values of elements and the time of expected changes indicated in an aerodrome forecast should 3.3 TYPES OF AERONAUTICAL METEOROLOGICAL FORECASTS 3-1 Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale --`,,```,,,,````-`-`,,`,,`,`,,`--- 3.3.3 Finally, forecasts also differ in regard to the period of validity or fixed time of validity for which they are normally prepared, as in Table 3-3.
  30. 30. 3-2 Chapter 3. Forecasts Table 3-1. ‘Qpes of aeronautical meteorological forecasts, including SIGMET and AIRMET information, warnings, volcanic ash advisories and tropical cyclone advisories Responsibility for preparing/ issuing the forecast Type of forecast Arealairspace covered Sage of flight planning Aerodrome forecast Aerodrome Pre-flight and in-flight Aerodrome meteorological office Landing forecast Aerodrome (especially approach and touchdown zone) In-flight Aerodrome meteorological office Take-off forecast Runway complex Pre-flight Aerodrome meteorological OffiCe Route, route system(s) or arealconditions at levels applicable to the operation Pre-flight and in-flight SIGMET information Ftight information region (FIR) or control arealall levels used for flight operations, including, if applicable, supersonic operations Pre-flight and in-flight Meteorologicalwatch office (MWO) AIRMET information Flight information region (FIR) or control area or a sub-areathereoflall flight levels up to FL 100 (FL 150 in mountainous areas) Pre-flight and in-flight Meteorologicalwatch office (MWO) Aerodrome warnings Aerodromeisuriace conditions Parked aircraft, aerodrome installations Aerodrome meteorological office Wind shear warnings Aerodrome and approachltake-off paths between runway level and 500 m (1 600 fl), or higher, if necessary In-flight and prior to and during take-off Aerodrome meteorological office Volcanic ash advisories Area (FIRS) of volcanic ash cloud occurrence Pre-flight and in-flight Volcanic ash advisory centre (VAAC) Tropical cyclone advisories Area (FIRS) of tropical cyclone occurrence Pre-flight and in-flight Tropical cyclone advisory centre (TCAC) Forecasts of en-route conditions --`,,```,,,,````-`-`,,`,,`,`,,`--- World andlor regional area forecast centre (WAFCIRAFC); Aerodrome meteorological OffiCe Note.- For details on SIGMET and AIRMET information and warnings, as well as volcanic ash and tropical cyclone advisories, see Chapter 4. Copyright International Civil Aviation Organization Provided by IHS under license with ICAO No reproduction or networking permitted without license from IHS Not for Resale

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