Service Name

SIGMET information

Service Abstract

A SIGMET is a weather report of hazardous weather for aircraft. In its raw form, it is abbreviated text. But SIGMETs are often also displayed with boxes drawn on charts.

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.

Common Service Definition

The service definition for the En-route Significant Weather information service is currently under development by the MET3SG Task Team on Service Architecture. See IWXXM SIGMET Subscription and Request Service.

Significant Meteorological Information or SIGMET is issued by meteorological authorities to provide information about significant meteorological phenomena that may pose a hazard to all aircraft.

It is a crucial part of aviation weather services and is designed to help pilots make informed decisions about flight plans and to ensure the safety of passengers and crew.

Service Implementation Status

The information is conveyed in a concise and standardized format to ensure that it can be easily understood and acted upon by pilots.

Service Information

A SIGMET gives a concise description of the phenomena in abbreviated plain language.

The following are examples of weather phenomena that may be described in a SIGMET:

• Thunderstorms

• Cyclones (Tropical Revolving Storms)

• Severe turbulence

• Severe icing

• Severe Mountain Waves

• Dust or Sand Storms

• Volcanic Ash

Service Provision

Service Provider Organization

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

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.

Data Origination

SIGMET information is often based on special air-reports; it may also be based on weather satellite data and on ground-based observations, such as weather radar observations, or on forecasts.

Provision Architecture

SIGMET information is issued by MWOs and disseminated to aircraft in flight through associated ATS units. Aircraft in flight should be given, on the initiative of FICs, SIGMET information affecting their routes to a distance equivalent to 2 hours’ flying time ahead of the position of the aircraft.

SIGMETs are disseminated to MWOs, WAFCs and to other meteorological offices as determined by RAN agreement. Furthermore, SIGMETs are transmitted to international OPMET databanks and to the international centres responsible for operation of the AFS satellite distribution systems. In addition, SIGMETs for volcanic ash cloud are disseminated to VAACs. Operators are supplied with SIGMET information mainly from meteorological offices. They can also obtain this information through various automated meteorological information systems or through automated information systems for pre-flight planning. SIGMETs are to be available at departure aerodromes for the whole route.

Service Consumption

Service Consumer Organization

The purpose of SIGMET information is to advise pilots of the occurrence or expected occurrence of en-route weather phenomena which may affect the safety of aircraft operations.

Consumer Usage

SIGMET is an essential part of aviation weather services and provides critical information about significant meteorological phenomena that can pose a hazard to aircraft in flight. It is a vital tool for flight planning and for ensuring the safety of passengers and crew. By understanding how to read and interpret SIGMET information, pilots can make informed decisions about their flight plans and avoid hazardous weather conditions.