Introduction to SIGMET 28 June 2016 Japan Meteorological Agency
SIGMET Definition SIGMET information Information issued by a meteorological watch office concerning the occurrence or expected occurrence of specified en-route weather phenomena which may affect the safety of aircraft operations. SIGMET information: Significant Meteorological information From ICAO Annex 3 What is en-route? What affects the safety of aircraft operations? What is a Meteorological Watch Office?
En route Instrument Flight Rules (IFR): From completion of Initial Climb through cruise altitude and completion of controlled descent to the Initial Approach Fix (IAF). Visual Flight Rules (VFR): From completion of Initial Climb through cruise and controlled descent to the VFR pattern altitude or 1,000 feet above runway elevation, whichever comes first. From Phases of Flight, the CAST/ICAO Common Taxonomy Team en-route
SIGMET Types There are three SIGMET types. WS SIGMET TS : Thunderstorm TURB : Turbulence ICE : Icing MTW : Mountain wave DS : Duststorm SS : Sandstorm RDOACT : Radioactive cloud WV SIGMET VA : Volcanic ash WC SIGMET TC : Tropical cyclone
Impact on Flights Thunderstorms and other convective weather Lightning, Severe turbulence, Severe icing In-flight icing Structural icing on wings and control surfaces increases aircraft weight, degrades lift, generates false instrument readings and compromises aircraft control. Can also enter engines and damage blades Turbulence (CAT, MTW) Non-convective turbulence can range from mildly discomforting passengers and crew to temporary loss of control and injuring crew and passengers. There have been deaths from turbulence encounters. From a presentation given at the ICAO APAC SIGMET seminar 2007
Volcanic Ash Impact on flights Ash can stop engines, affect control surfaces, prevent communications, affect vital instrument readings and make it impossible to see through windscreens Dust storms and Sand storms Similar in many respects to the impact of volcanic ash Tropical Cyclones Very strong winds, significant convective activity including thunderstorms From a presentation given at the ICAO APAC SIGMET seminar 2007
Meteorological Watch Office MWO shall: maintain continuous watch over meteorological conditions affecting flight operations within its area of responsibility prepare SIGMET and other information relating its area of responsibility supply SIGMET information and, as required, other meteorological information to associated air traffic services units disseminate SIGMET From ICAO Annex 3 The meteorological authority concerned should ensure that the MWO obligations and responsibilities are clearly defined and assigned to the unit designated to serve the MWO. From the ICAO APAC Regional SIGMET Guide
Handling of Simultaneous Phenomena Only one phenomenon shall be included in each SIGMET message. WSJP31 RJTD 040945 RJJJ SIGMET A01 VALID 040945/041345 RJTD- RJJJ FUKUOKA FIR SEV TURB FCST WI N3400 E13300 -N3400 E13800 -N3630 E13730 -N3630 E13230 -N3400 E13300 FL360/390 MOV E 35KT INTSF. SEV TURB FCST WI N3400 E13300 -N3500 E13800 -N3730 E13730 - N3630 E13230 -N3400 E13300 FL270/300 MOV E 35KT NC= Divide into two SIGMET messages. WSJP31 RJTD 040945 RJJJ SIGMET A01 VALID 040945/041345 RJTD- RJJJ FUKUOKA FIR SEV TURB FCST WI N3400 E13300 -N3400 E13800 -N3630 E13730 -N3630 E13230 -N3400 E13300 FL360/390 MOV E 35KT INTSF= WSJP31 RJTD 040946 RJJJ SIGMET B02 VALID 040946/041346 RJTD- RJJJ FUKUOKA FIR SEV TURB FCST WI N3400 E13300 -N3500 E13800 -N3730 E13730 -N3630 E13230 -N3400 E13300 FL270/300 MOV E 35KT NC= For WC and WV SIGMET, two volcanic ash clouds or two centres of tropical cyclones simultaneously affecting the relevant FIR can be included in one SIGMET message.
SIGMET Format SIGMET structure WMO header First line of SIGMET Main body Refer to other presentations
WMO Header T 1 T 2 A 1 A 2 ii CCCC YYGGgg [CCx] Space Space Space [ ] denotes an optional or conditional element T 1 T 2 Data type designator WS - for SIGMET for meteorological phenomena other than volcanic ash cloud or tropical cyclone WC - for SIGMET for tropical cyclone WV - for SIGMET for volcanic ash A 1 A 2 Country or territory designators Assigned according to Table C1, Part II of Manual on the Global Telecommunication System, Volume I - Global Aspects (WMO Publication No. 386) ii Bulletin number Assigned on national level according to p 2.3.2.2, Part II of Manual on the Global Telecommunication System, Volume I - Global Aspects (WMO Publication No. 386) From the ICAO APAC Regional SIGMET guide
WMO Header T 1 T 2 A 1 A 2 ii CCCC YYGGgg [CCx] Space Space Space [ ] denotes an optional or conditional element CCCC ICAO location indicator of the communication centre disseminating the message YYGGgg date/time group YY is the date and GGgg is the time of transmission of the SIGMET in hours and minutes UTC. [CCx] CCx should be used only when issuing a correction to a SIGMET which had already been transmitted. The third letter x takes the value A for the first correction, B for the second correction, etc. From the ICAO APAC Regional SIGMET guide
WMO Header Examples: WSTH31 VTBS 121200 WVJP31 RJTD 010230 WCNG21 AYPY 100600 CCA See the ICAO APAC Regional SIGMET Guide APPENDIX D - WMO headings (WMO AHL) for information on SIGMET bulletins.
First line of SIGMET CCCC SIGMET [nn] n VALID YYGGgg/YYGGgg CCCC- Space CCCC SIGMET [nn] n VALID YYGGgg/ YYGGgg CCCC- ICAO location indicator of the ATS unit serving the FIR to which the SIGMET refers Message identifier and Daily sequence number. The numbering of SIGMETs starts every day at 0001 UTC. Validity period of the SIGMET given by date/time group of the beginning and date/time group of the end of the period ICAO location indicator of the issuing MWO and hyphen Examples: SIGMET 5, SIGMET 03, SIGMET A3, SIGMET A06 Examples: VALID 180540/180940, VALID 182230/190230 From the ICAO APAC Regional SIGMET guide
Period of Validity The following regulations apply when determining the validity period: The period of validity of a WS SIGMET should be not more than 4 hours; The period of validity of a WC or WV SIGMET should not be more than 6 hours; In the case of a SIGMET for an observed phenomenon: the filing time (date/time group in the WMO header) should be the same or very close to the time in the date/time group indicating the start of the SIGMET validity period; In the case of a SIGMET for a forecast phenomenon: the beginning of validity period should be the time of the expected commencement (occurrence) of the phenomenon in the MWO area of responsibility; the time of issuance of a WS SIGMET should be not more than 4 hours before the start of validity period; and for WC and WV SIGMET the lead time should be not more than 12 hours. Issuance time Start of validity period End of validity period From the ICAO APAC Regional SIGMET guide Issuance time Occurrence time end of the period OBS No more than 4 (or 6) hours FCST No more than 4 (or 12) hours No more than 4 (or 6) hours
First line of SIGMET Examples: RPMM SIGMET 3 VALID 121100/121700 RPLL- WSJC SIGMET A04 VALID 202230/210430 WSSS-
Cancellation of SIGMET If the phenomenon for which a SIGMET was issued is no longer present or no longer expected within the validity period, the SIGMET shall be cancelled by the issuing MWO. The cancellation is done by issuing same type of SIGMET with the following structure: 1. WMO heading with the same data type designator 2. First line that contains as period of validity the remaining time of the original period of validity 3. Second line, which contains the name of the FIR, the combination CNL SIGMET, followed by the sequential number of the original SIGMET and its original validity period
Cancellation of SIGMET For cancellation of the following SIGMET: WSXY31 YUSO 101200 YUDD SIGMET J05 VALID 101200/101600 YUSO- YUDD SHANLON Same data FIR type designator The cancellation SIGMET is: WSXY31 YUSO 101430 YUDD SIGMET J06 VALID 101430/101600 YUSO- YUDD SHANLON FIR CNL SIGMET J05 101200/101600=
Cancellation of SIGMET For cancellation of the following SIGMET: WSXY31 YUSO 101200 YUDD SIGMET J05 VALID 101200/101600 YUSO- YUDD SHANLON FIR The cancellation SIGMET is: The time of issuance should be within the period of validity. WSXY31 YUSO 101430 YUDD SIGMET J06 VALID 101430/101600 YUSO- YUDD SHANLON FIR CNL SIGMET J05 101200/101600=
Cancellation of SIGMET For cancellation of the following SIGMET: WSXY31 YUSO 101200 YUDD SIGMET J05 VALID 101200/101600 YUSO- YUDD SHANLON FIR The sequential number The cancellation SIGMET is: follows that of the original SIGMET. WSXY31 YUSO 101430 YUDD SIGMET J06 VALID 101430/101600 YUSO- YUDD SHANLON FIR CNL SIGMET J05 101200/101600=
Cancellation of SIGMET For cancellation of the following SIGMET: WSXY31 YUSO 101200 YUDD SIGMET J05 VALID 101200/101600 YUSO- YUDD SHANLON FIR The cancellation SIGMET is: WSXY31 YUSO 101430 YUDD SIGMET J06 VALID 101430/101600 YUSO- YUDD SHANLON FIR CNL SIGMET J05 101200/101600= The start of the period should be the same as the issuance time, and the end should be the same as that of the original SIGMET.
Cancellation of SIGMET For cancellation of the following SIGMET: WSXY31 YUSO 101200 YUDD SIGMET J05 VALID 101200/101600 YUSO- YUDD SHANLON FIR The cancellation SIGMET is: WSXY31 YUSO 101430 YUDD SIGMET J06 VALID 101430/101600 YUSO- YUDD SHANLON FIR CNL SIGMET J05 101200/101600= CNL SIGMET followed by the SIGMET s sequential number and the period of validity.
SIGMET Dissemination The telecommunication facilities used for the exchange of the SIGMET should be the aeronautical fixed service (AFS). Currently, AFTN links should be used by the MWOs to send the SIGMET, as follows: to the adjacent MWOs and ACCs using direct AFTN addressing; when required for VOLMET or D-VOLMET, SIGMET should be sent to the relevant centre providing the VOLMET service; SIGMET should be sent to all regional OPMET Data Banks (RODB); it should be arranged that SIGMET is relayed to the SADIS and WIFS providers for public internet dissemination, as well as to the WAFCs London and Washington, either through the ROBEX scheme, or directly by the issuing MWO; SIGMET for volcanic ash should be disseminated to the responsible VAAC. From the ICAO APAC Regional SIGMET guide
SIGMET Dissemination * SIGMET information should be transmitted to aircraft with the least possible delay on the initiative of the responsible ATS unit.
Priority Indicator A Priority indicator represents the AFTN message category and dissemination priority. The SIGMET priority indicator is FF. The TAF & METAR priority indicator is GG. SIGMET has higher dissemination priority than TAF & METAR.
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