Review of SIGMET - wmo.int · Review of SIGMET Lawrence Pologne. Caribbean Institute for Meteorology and Hydrology, Barbados . ¾Usage of SIGMET ... TNCC SIGMET 4 VALID 250630 TNCC

WMO Seminar /Workshop for Aeronautical Competencies and SIGMETs

NAM/CAR RegionsCosta Rica, 25-27 August 2015

Review of SIGMETLawrence Pologne

Caribbean Institute for Meteorology and Hydrology, Barbados

Usage of SIGMETMWO’s responsibility and ICAO’s requirementsSIGMET phenomena and issuance criteria SIGMET type and structureSome Incorrect Examples

Introduction

• Purpose of AWS is to ensure that flights are smooth and safe. This can only be achieved if we enhance the capabilities of the MWO/M Operations.

• Deficiency in SIGMET issuance; in some cases non issuance of SIGMET.– Direct impact on safety of international air navigation.

• Incorrect format.– Different forecasters and different forecast centres use different methods

for SIGMET issuance.– Lead to confusion within the aviation community.– Lead to rejection of messages in automated systems.

• ICAO/WMO have initiated efforts to improve on SIGMET issuance.– Discussed possibility and benefits of establishing Regional SIGMET Advisory

Centres (RSAC).• Need to ensure that everybody stays in line with the ICAO recommended

standards.

SIGMET Issuance

SIGMET message:• provide information on

hazardous meteorological phenomena which may affect safety of aircraft operations;

• of highest priority among other types of meteorological information provided to aviation users

• Primary purpose is for in-flight planning

SIGMET Issuance

Example

• Thunderstorm is a hazardous meteorological phenomena, associated with turbulence, icing, lightning or even hailstone;

• Pilot in-flight often avoids entering into area of significant convection;

• Flight routes may be blocked;

• More fuel may be required;

• Pilot need to plan for significant convection affecting planned flight routes

SIGMET Issuance – Usage of SIGMET

Pre-Flight Planning (before departure)

• Flight despatch of airline operator (or ground handling agent) gets all SIGMETs affecting the whole flight routes before departure – to plan for fuel requirement;

• SIGMETs covering the whole flight routes (in respect of time, altitude and geographical extent) should be supplied by aerodrome meteorological office as part of flight document;

• Flight crew members use SIGMET before departure.


In-Flight Planning (en-route)

• Pilot get real-time SIGMETs via

air traffic controller (voice communication)

VOLMET broadcast

D-VOLMET

ACARS / other telecommunication means


VOLMET

D-VOLMET

Voice communication

Airline Operator

ACARS or other telecommunication means

Meteorological Watch Office•Issuing SIGMET for FIR under its responsibility•Collect SIGMET for other FIRs via OPMET data exchange, WAFS, etc.

Air Traffic Controller

In-Flight Planning (en-route) – flow of SIGMETs

Document

ICAO Annex 3, Meteorological Service for International Air Navigation

• State the responsibility of Meteorological Watch Office (MWO)

MWO’s responsibility and ICAO’s requirements

Responsibility of MWOs as required in ICAO Annex 3

3.4 Meteorological watch offices

3.4.1 A Contracting State, having accepted the responsibility for providing air traffic services within a flight information region or a control area, shall establish, on the basis of regional air navigation agreement, one or more meteorological watch offices, or arrange for another Contracting State to do so.

3.4.2 A meteorological watch office shall:

a) maintain continuous watch over meteorological conditions affecting flight operations within its area of responsibility;

b) prepare SIGMET and other information relating to its area of responsibility;

c) supply SIGMET information and, as required, other meteorological information to associated air traffic services units;

d) disseminate SIGMET information;


3.4 Meteorological watch offices (continued)

e) when required by regional air navigation agreement, in accordance with 7.2.1:

1) prepare AIRMET information related to its area of responsibility;

2) supply AIRMET information to associated air traffic services units; and

3) disseminate AIRMET information;

f) supply information received on pre-eruption volcanic activity, a volcanic eruption and volcanic ash cloud for which a SIGMET has not already been issued, to its associated ACC/FIC, as agreed between the meteorological and ATS authorities concerned, and to its associated VAAC as determined by regional air navigation agreement; and



g) supply information received concerning the release of radioactive materials into the atmosphere, in the area for which it maintains watch or adjacent areas, to its associated ACC/FIC, as agreed between the meteorological and ATS authorities concerned, and to aeronautical information service units, as agreed between the meteorological and appropriate civil aviation authorities concerned. The information shall comprise location, date and time of the release, and forecast trajectories of the radioactive materials.

Note.— The information is provided by WMO regional specialized meteorological centres (RSMC) for the provision of transport model products for radiological environmental emergency response, at the request of the delegated authority of the State in which the radioactive material was released into the atmosphere, or the International Atomic Energy Agency (IAEA). The information is sent by the RSMC to a single contact point of the national meteorological service in each State. This contact point has the responsibility of redistributing the RSMC products within the State concerned. Furthermore, the information is provided by IAEA to RSMC co-located with VAAC London (designated as the focal point) which in turn notifies the ACCs concerned about the release.



3.4.3 Recommendation.— The boundaries of the area over which meteorological watch is to be maintained by a meteorological watch office should be coincident with the boundaries of a flight information region or a control area or a combination of flight information regions and/or control areas.

Some of the Caribbean MWOsMWOs Headers

Georgetown, Guyana WSCA31 SYCJ 290930 SYCJ SIGMET 1 VALID 290930/191330 SYCJ‐GEORGETOWN FIR ……….

Curacao, Curacao WSNU20 TNCC 250630 TNCC SIGMET 4 VALID 250630 TNCC‐TNCC CURACAO FIR ………

Piarco, Trinidad WVCA31 TTPP 201545 TTZP SIGMET 1 VALID 201545/211545 TTPP‐TTZP PIARCO FIR ……………….

San Juan, Puerto Rico WSCA TJSJ 101555 TJZS SIGMET YANKEE 1 VALID 101600/102000 TJSJ‐ ……..

Kingston, Jamaica WSCA31 MKJP 301500 MKJK SIGMET 1 VALID 301500/3019000 MKJP‐MKJK KINGSTON ………..

Some of the Caribbean MWOsMWOs Headers

Havana, Cuba WSCU31 MUHA 250818 MUFH SIGMET 2 VALID 250817/251217 MUHA –MUFH HABANA FIR

Port‐Au‐Prince, Haiti WSCA31 MTPP 061055 MTEG SIGMET 2 VALID 061050/061450 MTPP‐MTEG PORT‐AU‐PRINCE FIR …………..

Santo Domingo, Dominican Republic

WSCA31 MDSD 050645 MDCS SIGMET 3 VALID 050645/050645 MDSD‐MDCS SANTO DOMINGO FIR……………….

SIGMET Language and Units Used

• SIGMETs are usually worded in abbreviated English language using the standard abbreviations authorized in the Manual of Word Abbreviations (MANAB) and those allowed by the Manual of Surface Weather Observations (MANOBS).

• Except for heights (100’s of feet), units must be stated explicitly. All distances must be given in nautical miles (NM), visibility in statute miles (SM), times in UTC (Z), and speeds in knots (KT).

Types of SIGMET

Although ICAO Annex 3 provides one general SIGMET format, which encompasses all of the specified weather phenomena, it is convenient to distinguish between three types of SIGMET, as follows:

• WS SIGMET for TS, TURB, ICG, MTW, LLWS, DS, SS, RDOACT CLD

• WV SIGMET for volcanic ash (VA)

• WC SIGMET for tropical cyclones (TC)

The type of SIGMET can be identified through the data type designator included in the WMO abbreviated heading of the SIGMET message.

Description of symbolic form T1T2A1A2ii CCCC YYGGgg [CCx]

Symbol Interpretation

T1 Data type designator (W for Warnings (WMO-No. 386))

T2 Data type designator (S, C, V for SIGMET (WMO-No. 386))

A1A2 Geographical designator (where the message applies to, not the issuing country)

ii Bulletin number (01–19 for global distribution, 20–39 for inter-regional distribution (as per WMO regions))

CCCC International four-letter location indicator of the centre originating or compiling the bulletins

YYGGgg International date-time group

Format of SIGMETNote: In the following text, square brackets [ ] are used to indicate an optional or conditional element, and angled brackets < >are used for symbolic representation of a variable element, which in the real SIGMET accepts concrete alphanumeric values.WMO headerThe Manual on the Global Telecommunication System (WMO-No. 386) recommends the use of the following abbreviated headings for bulletins containing meteorological information.

Description of CCCC SIGMET [n]nn VALID YYGGgg/YYGGgg CCCC-

Symbol Interpretation

CCCC ICAO location indicator of the ATS unit serving the FIR to which the SIGMET refers

SIGMET Message identifier

[n]nn Daily alphanumeric sequence

VALID Period of validity indicator

YYGGgg/YYGGgg Validity period of SIGMET given by date/time group of the beginning and date/time group of the end of the period

CCCC- ICAO location indicator of the MWO that issued the message, and a hyphen “-” (without a space); separates the preamble from text .

First line--CCCC SIGMET [n]nn VALID YYGGgg/YYGGgg CCCC-

Daily alphanumeric sequence

A SIGMET message shall be numerically sequenced:

o numbering of a SIGMET message begins at one;

o the number is incremented by one when updating the message, including cancellation;

o the sequence number shall correspond with the number of SIGMET messages issued for an event within a FIR since 0000Z on the day concerned; and

o the numbering is thus reset at 0000Z (messages are not updated at 0000Z for the sole purpose of resetting the number).

Some stations use a letter/number system. E.g. SIGMET A1 while others use the NATO phonetic alphabet.

If more than one weather phenomena is occurring at the same time one SIGMET may have the sequence number CHARLIE 3 (the 3rd SIGMET issued for the phenomena associated with CHARLIE) while another can have DELTA 2 (the 2nd SIGMET issued for the phenomena associated with DELTA)

Symbol Lead time ie time of issuance – up to (hours)

Validity period (hours)

WS 4 4

WV 12 6

WC 12 6

Example (1): For an ongoing phenomenon:

WSCA31 TTPP 161220TTZP SIGMET 3 VALID 161220/161620 TTPP-

Example (2): For an expected phenomenon (expected time of occurrence 0315Z):

WSCA31 TTPP 040115TTZP SIGMET 1 VALID 040315/040715 TTPP-

Validity period and lead time of SIGMET

Element 1Location indicator

of the FIR

Element 2Name of the FIR

Element 3Description of the

phenomenon

Element 4Observed or

forecast

Element 5Location

<CCCC> <name> FIR <Phenomenon> OBS [AT <GGggZ>] FCST

Geographical location of the phenomenon

Element 6Level

Element 7Movement or expected

movement

Element 8Change in intensity

FL<nnn/nnn> SFC/FL<nnn> TOP

FL<nnn>

MOV <direction, speed> KT QS

INTSFYG or WKNG or NC

Format of the meteorological part of a WS SIGMET

The meteorological part of a WS SIGMET consists of eight elements identified in the following table (this table has been divided into two parts due to horizontal space constraints):

Location indicator and name of the FIR (element 1 and 2)

Example (1): TTZP PIARCO FIRExample (2): MKJK KINGSTON FIR

Description of the phenomenon (element 3)The description of the phenomenon consists of a qualifier and a phenomenon abbreviation. SIGMET will be issued for the following phenomena (with only one phenomenon in each SIGMET):

• Thunderstorm

(TS): FRQ or SQLN, with hail,

tornado/waterspout as necessary

• Turbulence (TURB): only SEV

• Icing (ICG): only SEV with or

without FZRA

• Mountain waves (MTW):

only SEV

• Low Level wind shear (LLWS)

• Dust storm (DS): only HVY

• Sand storm (SS): only HVY

• Radioactive cloud: RDOACT CLD

Indication if the phenomenon is observed or forecast (element 4)OBS [AT <GGggZ>] or FCST

The use of “OBS” occurs if either:

• there has been a recent (normally within a two hour period preceding

the issuance time of the SIGMET) direct observation of the

phenomenon (i.e. METAR, PIREP); or

• there has been a recent indirect observation of the phenomena (i.e.

remote sensing imagery) or the observation of a meteorological

element (i.e. strong wind, freezing precipitation), which leads the

forecaster to believe that the phenomenon is occurring.When FCST is used, it is assumed that the time of the occurrence or commencement of the phenomenon coincides with the beginning of the period of validity in the first line of the SIGMET.

“FCST” = forecast“OBS” = observed and expected to continue i.e. (observed and forecast)

Location of the phenomenon (element 5)

The location of the phenomenon is depicted as an area using coordinate points:

• the area can be described as a circle, a line or a polygon; and• distances are in nautical miles (NM), direction to one of the eight points

of compass (octants).

Note (1): A radial distance is used to define the size of the circle.Note (2): The area is defined by a distance either side of the line.Note (3): Polygon must be closed. The last coordinate point is a repeat of the first one.Coordinate points:• The international (ICAO) SIGMET message describes a coordinate point

using a latitude and longitude only.Description Recommended maximum number of

coordinate points

Circle 1

Line 4

Polygon 7

Example of the format for coordinate pointsDescription International (ICAO)

Circle WTN 45 NM OF N4643 W07345

Line WTN 45 NM OF LINE N4459 W07304 -N4855 W07253 -N5256 W06904

Polygon WTN N4502 W07345 -N4907 W07331 -N5345 W06943 -N5256 W06758 -N4848 W07149 -N4508 W07206 - N4502 W07345

Flight level and extent (element 6)FL<nnn/nnn>SFC/FL<nnn>TOP FL<nnn>

The location and extent of the phenomenon in the vertical is given by one or more of the above abbreviations, as follows:

• Reporting a layer “FL<nnn/nnn>”, where the lower level is reported

first; this is used particularly in reporting turbulence and icing

• Reporting a layer with reference to one FL using “SFC/”

• Reporting the level of the tops of the TS clouds using the

abbreviation “TOP”

Example (1): SEV TURB…FL220/270

Example (2): SEV ICG (FZRA)…SFC/FL030

Example (3): FRQ TS…TOP FL340

Movement or expected movement (element 7)

MOV <direction, speed>KT or QS

Direction of movement is given with reference to one of the sixteen points of compass (radials). Speed is given in knots (KT). The abbreviation QS is used if no significant movement is expected.

Example: MOV SSE 15KT

Change in intensity (element 8)The expected evolution of the phenomenon’s intensity is indicated by one of the following abbreviations:

• INTSFYG: intensifying

• WKNG: weakening

• NC: no change

RDOACT CLD event with limited informationIn the case of a RDOACT CLD event and that limited information is available to the forecaster (i.e. first issuance of a RDOACT CLD SIGMET), the following elements may be set as ‘’UNKNOWN’’:• Level unknown (element 6): FL UNKNOWN

• Movement unknown (element 7): MOV UNKNOWN

• Change in intensity unknown (element 8): INTSTY UNKNOWN

Example (1):

WSCN04 CWAO 161220CZYZ SIGMET R1 VALID 161220/161620 CWUL-CZYZ TORONTO FIR RDOACT CLD OBS AT 1205Z WTN 10 NM OF N4350 W07905FL UNKNOWN MOV UNKNOWN INTSTY UNKNOWN=

Example (2):

WSCN24 CWAO 161220CZYZ SIGMET R1 VALID 161220/161620 CWUL-CZYZ TORONTO FIR RDOACT CLD OBS AT 1205Z WTN 10 NM OF /N4350 W07905/25 E CYYZ FL UNKNOWN MOV UNKNOWN INTSTY UNKNOWNRMK GFACN33=

SIGMET phenomenon covering two FIRs

The above phenomenon requires two SIGMET messages, one per FIR. The description will be identical in both

messages (1) and (2) below:

Message (1):

WSCN22 CWAO 161220CZEG SIGMET B1 VALID 161220/161620 CWEG-CZEG EDMONTON FIR «meteorological part»RMK GFACN32/CZWG WINNIPEG FIR SIGMET A1=

Message (2)

WSCN23 CWAO 161220CZWG SIGMET A1 VALID 161220/161620 CWEG-CZWG WINNIPEG FIR «meteorological part»RMK GFACN32/CZEG EDMONTON FIR SIGMET B1=

• A phenomenon moving from one FIR to another is treated as an ongoing phenomenon. No forecast event SIGMET messages would be sent for the second FIR.

SIGMET phenomenon now within only one FIR

The above phenomenon is a continuation of the previous. In other words, the area has moved southeastward with time. SIGMET A2 is an update of A1 while SIGMET B2 is a cancellation of B1 since the phenomenon no longer affects the Edmonton FIR. The messages would look like this:

Message (1):

WSCN22 CWAO 161530CZEG SIGMET B2 VALID 1615300/161620 CWEG-

CZEG EDMONTON FIR CNCL SIGMET B1 161220/161620

RMK GFACN32/CZWG WINNIPEG FIR SIGMET A2=

Message (2):

WSCN23 CWAO 161530CZWG SIGMET A2 VALID 161530/161930 CWEG-CZWG WINNIPEG FIR «meteorological part»RMK GFACN32=

ICAO Annex 3 Appendix 6

Note

Not including:

• Isolated thunderstorms

• Tropical depression

Note

Not including:

• Moderate turbulence

• Moderate icing




We cannot use satellite/radar to observe severe wx/turbulence.A pilot report can, however.

Pilots generally use their subjective assessments for severe turbulence(based on size/weight of aircraft)


Incorrect examples

Date is 28 February 2011

WSXX20 XXXX 282300XXXX SIGMET 4 VALID 282300/290300 XXXX-XXXX ……..

Date of 29 February 2011 not exist.

The correct validity period should be:

WSXX20 XXXX 282300XXXX SIGMET 4 VALID 282300/010300 XXXX-XXXX ……..

If interpreted by a human being, it is still OK. But unlikely for automated systems.

Incorrect examples

WSXX90 XXXX 311600

XXXX SIGMET 6 VALID 311600/312000 UTC XXXX-

XXXX XXXXXXX FIR NIL SIGMET=

• UTC is not required

• “NIL SIGMET” is not required for dissemination via AFTN. It is only required for VOLMET/D-VOLMET.

Incorrect examples

WSXX90 XXXX 311600

XXXX SIGMET 7 VALID 311600/312000 UTC XXXX-

XXXX XXXXXXX FIR SEV ICING FCST ……=

• correct abbreviation should be “SEV ICE”

Incorrect examples

WSFR34 LFPW 191604XXXX SIGMET 7 VALID 191600/192000 XXXX-XXXX XXXXXXXXXX FIR/UIR : EMBD TS OBS AND FCST ON XXXXXXXX FIR FROM XXXXXX’S COAST TO XXXXXXXX'S MOUNTAIN TOP CB FL280/FL320 EXTEND TO XXXXX'S EAST-COAST WKN=

• “:” is not required• “OBS” should mean “observed and forecast” and hence

“AND FCST” is not necessary• Description of location a bit complicated• “TOP CB FL280/FL320” should be “TOP FL320”• Movement (direction in 16-point compass)

ICAO Annex 3 Appendix 6 Table A6-1


SIGMET Issuance – MWO’s responsibility and ICAO’s requirements

Other ICAO’s requirement relevant to SIGMET:• ICAO Annex 3

Chapter 9 - Service for operators and flight crew members;

Chapter 10 – Information for air traffic services, search and rescue services and aeronautical information services;

APPENDIX 6. Technical specifications related to SIGMET and AIRMET information, aerodrome warnings and wind shear warnings and alerts;

APPENDIX 8. Technical specifications related to service for operators and flight crew members;

APPENDIX 9. Technical specifications related to information for air traffic services, search and rescue services and aeronautical information services;

APPENDIX 10. Technical specifications related to requirements for and use of communications.

7.1 SIGMET information

7.1.1 SIGMET information shall be issued by a meteorological watch office and shall give a concise description in abbreviated plain language concerning the occurrence and/or expected occurrence of specified en-route weather phenomena, which may affect the safety of aircraft operations, and of the development of those phenomena in time and space.

7.1.2 SIGMET information shall be cancelled when the phenomena are no longer occurring or are no longer expected to occur in the area.

7.1.3 The period of validity of a SIGMET message shall be not more than 4 hours. In the special case of SIGMET messages for volcanic ash cloud and tropical cyclones, the period of validity shall be extended up to 6 hours.

SIGMET information as required in ICAO Annex 3

7.1 SIGMET information (continued)

7.1.4 Recommendation.— SIGMET messages concerning volcanic ash cloud and tropical cyclones should be based on advisory information provided by VAACs and TCACs, respectively, designated by regional air navigation agreement.

7.1.5 Close coordination shall be maintained between the meteorological watch office and the associated area control centre/flight information centre to ensure that information on volcanic ash included in SIGMET and NOTAM messages is consistent.

7.1.6 SIGMET messages shall be issued not more than 4 hours before the commencement of the period of validity. In the special case of SIGMET messages for volcanic ash cloud and tropical cyclones, these messages shall be issued as soon as practicable but not more than 12 hours before the commencement of the period of validity. SIGMET messages for volcanic ash and tropical cyclones shall be updated at least every 6 hours.

SIGMET information as required in ICAO Annex 3

Example

ZCZC SMB1825 080740FF VHHHYMYX080738 VTBBYPYXWSAU21 AMRF 080738YMMM SIGMET ML05 VALID 080800/081200 YMRF-YMMM MELBOURNE FIR SEV TURB FCST WI YBLA -YCOM - S3730 E15100 -LOLLY - YFLI BLW FL080 MOV E 30KT WKNSTS:REV ML02 08040/080800NNNN

1st ICAO location indicatorThe communication centre disseminating the message. Usually, this is the same as the location indicator of the issuing MWO.

AFTN header

2nd ICAO location indicatorThe ATS unit serving the FIR or CTA.Ref. ICAO Annex 3 17th edition Table A6-1, under column “Detailed content”

A Typical SIGMET Message

3rd ICAO location indicatorThe issuing MWO.Ref. ICAO Annex 3 17th edition Table A6-1, under column “Detailed content”

4th ICAO location indicatorThe FIR/CTA.Ref. ICAO Annex 3 17th edition Table A6-1, under column “Detailed content”

Name of FIR/CTA

WMO header

Date and Time of filing and Originator

Ending

Heading

Structure of the SIGMET message

A SIGMET message consists of:

• WMO heading: all SIGMET are preceded by an appropriate WMO

heading;

• First line: containing location indicators of the relevant ATS unit serving

the FIR and MWO, alphanumeric identification and period of validity;

• Meteorological part: containing meteorological information concerning

the phenomenon for which the SIGMET is issued; and

• Equal sign “=”: indicates the end of the message.

The first two parts of the SIGMET message are common for all SIGMET types. The content and format of the meteorological part is different depending on the type of SIGMET. Therefore, in the following paragraphs, the meteorological part of the WS, WV and WC types of SIGMET is described separately.

WMO Header for SIGMET information

SIGMET Type WMO Header Also commonly known as

SIGMET for meteorological phenomena other than volcanic ash or tropical cyclones

WS**** WS SIGMET

SIGMET for tropical cyclone WC**** WC SIGMETSIGMET for volcanic ash WV**** WV SIGMET

Tropical cyclone SIGMETs are referred to as WC SIGMET (due to the T1T2 section of the WMO header being set to WC);Volcanic ash cloud SIGMETs are referred to as WV SIGMET (due to the T1T2 section of the WMO header being set to WV); All other SIGMET types are referred to as WS SIGMET (due to the T1T2 section of the WMO header being set to WS).

SIGMET Structure Bulletin ID (WMO 386)

WSCA31

Originating OfficeMKJP

Issue Date/Time

301500

Other Info

COR

FIR

MKJK

Sequence Number

SIGMET 1

Validity

VALID301500/3019000

Originating office ‐

MKJP‐

FIR Meteorological InformationMKJK KINGSTON FIR EMBD TS OBS AT 1500Z WI N1600 W07500‐N1800 W07500‐N1810 W07840‐N1500 W07800

Status FCST MOV SE=

WSCA31 MKJP 301500 COR MKJK SIGMET 1 VALID 301500/3019000 MKJP-

MKJK KINGSTON FIR EMBD TS OBS AT 1500Z WI N1600 W07500-N1800 W07500-N1810 W07840-N1500 W07800 FCST

MOV SE=


Air Traffic Management

• Some air traffic management units refer to SIGMET for:

Air traffic flow management

Documents

Review of SIGMET - wmo.int · Review of SIGMET Lawrence Pologne. Caribbean Institute for Meteorology and Hydrology, Barbados . ¾Usage of SIGMET ... TNCC SIGMET 4 VALID 250630 TNCC