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8. MET - 1.0 GENERAL INFORMATION

MET - 1.0 GENERAL INFORMATION

 

• 1.1 General
  • 1.1.1 Meteorological Responsibility
  • 1.1.2 Meteorological Services Available
  • 1.1.3 Aviation Weather Services
  • 1.1.4 Weather Service Information
  • 1.1.5 Weather Observing Systems and Procedures at Major Aerodromes
  • 1.1.6 Pilot Reports
  • 1.1.7 Applicable International Civil Aviation Organization (ICAO) and World Meteorological Organization (WMO) Documents
  • 1.1.8 Differences from ICAO Annex 3
  • 1.1.9 Pilot Responsibility
• 1.2 Meteorological Observation and Reports
  • 1.2.1 Aeronautical Meteorological Stations and Offices
  • 1.2.2 Type and Frequency of Observations
  • 1.2.3 Flight Weather Documentation
  • 1.2.4 Automated Weather Observation System
  • 1.2.5 Limited Weather Information System (LWIS)
  • 1.2.6 Weather Services in Support of Approach UNICOM (AU)
  • 1.2.7 Runway Visibility Assessment (RVA)
• 1.3 Meteorological Forecasts and Charts
  • 1.3.1 Locations
  • 1.3.2 Hours of Service and Telephone Numbers of FICs
  • 1.3.3 World Area Forecast System (WAFS) Charts
  • 1.3.4 Aerodrome Forecasts
  • 1.3.5 Weather Information
  • 1.3.6 Area Forecasts and AIRMET
  • 1.3.7 Upper Level Wind and Temperature Forecasts
  • 1.3.8 ATC Weather Assistance
  • 1.3.9 Supplementary Information
• 1.4 VOLMET
  • 1.4.1 General

1.1 General

The Minister of Transport is responsible for the development and regulation of aeronautics and the supervision of all matters connected with aeronautics.

1.1.1 Meteorological Responsibility

Enquiries relating to the provision of aviation weather services should be addressed to NAV CANADA:

NAV CANADA
Aviation Weather Services
77 Metcalfe Street
Ottawa ON K1P 5L6
 
Tel. Toll-free (North America only): 1-800-876-4693
Fax: 613-563-3426
Fax Toll-free (North America only): 1-877-663-6656
E-mail:   service@navcanada.ca

Enquiries relating to regulations and standards for aviation weather services should be addressed to:

1.1.2 Meteorological Services Available

Aviation weather information is available from NAV CANADA FICs. Telephone numbers and hours of services are listed in the CFS and the WAS.

1.1.3 Aviation Weather Services

(a) Pilot Briefing Service

The Pilot Briefing Service is provided by NAV CANADA FICs to accommodate pilots at the pre-flight planning stage and for information updates while en route. Flight service specialists can access and display a full range of weather charts, imagery (i.e. satellite, lightning and radar) and aeronautical information (such as NOTAM, RSC and CRFI). They are qualified to provide briefings, consultation and advice and to interpret meteorological information. (See RAC 3.2 for details).

(b) Aviation Weather Web Site

NAV CANADA has re-hosted the NAV CANADA Aviation Weather Web Site (AWWS). Some of the features of the Web site include the following:

(i) Local Briefings: user-selected weather information within a 100-NM radius of any site in Canada that has a surface aviation weather observation program;

(ii) Regional Briefings: user-selected weather information within given regional areas selected by the user; and

(iii) Route Briefings: user-selected weather information along a user-defined narrow route.

In addition to the above, users can individually select all text, chart, and imagery observation and forecast products for display. They can also save regional area and route briefings for subsequent recall. A search engine is available to allow users to search documentation in the database, including FAQs (frequently asked questions). The URL for the AWWS is  http://www.flightplanning.navcanada.ca/.

(c) Other Pilot Weather Services

By arrangement with the U.S. National Weather Service, upper level wind and temperature forecasts in digital form are made available to operators in Canada for planning flights on a world-wide basis. Identical information is made available to the Gander Oceanic ATC Centre for planning transatlantic flights.

Aviation weather flight documentation is provided, subject to prior notification, as determined by the local weather service outlet in consultation with the operator’s local representative.

Operators requiring user-pay connections to the EC weather communications systems for pre-flight planning, flight documentation or flight watch purposes should apply to the Director General of the National Weather Services Directorate:

Director General
Weather and Environmental Prediction Services
Environment Canada
141 Laurier Avenue West, 2nd floor
Ottawa ON  K1A 0H3 

It is the responsibility of the operator to notify NAV CANADA, Aviation Weather Services, of new requirements. (See MET 1.1.1 for address.)

1.1.4 Weather Service Information

When planning a flight, pilots can obtain aviation weather and aeronautical information and file a flight plan through a NAV CANADA FIC. (See RAC 3.2 for details).

Radio communication should be established with an FIC on a FISE frequency if in-flight information is required to assist in making a decision or to terminate a flight, or to alter course before adverse weather conditions are encountered.

Pilot requests for initial pilot briefings while airborne are not encouraged because this practice leads to frequency congestion.

1.1.5 Weather Observing Systems and Procedures at Major Aerodromes

Information on the cloud-base height is obtained by use of laser ceilometers, ceiling projectors, ceiling balloons, pilot reports and observer estimation. Observations are provided to the local ATS units in the form of METAR and SPECI reports.

Temperature is read each hour from a mercury thermometer located in a ventilated screen; some stations have a remote read-out of this information located in the ATS facility or the weather observation office.

RVR observations are obtained by transmissometers and forward-scatter sensors. Observations representative of the touchdown and midpoint visibility averaged over 1 min and based on the light setting in use are automatically displayed in digital form in the local ATS unit. At locations where RVR information is accessible to the weather observer, the RVR is included in METAR and SPECI reports when it is 6 000 ft or less for the runway in use and/or the visibility is one SM or less. Refer to the METAR example (MET 3.15.3) for further details.

At some locations, a digital altimeter display system is provided in ATS units, as required.

Observations of slant visual range, vertical wind shear, trailing vortices and marked temperature inversions are not made in Canada.

(a) Reporting of Cloud Bases

There are two distinct methods of reporting cloud bases. It is vital to the pilot to be able to distinguish and recognize which method of reporting is in use. Heights in METAR and TAF are always stated as height AGL. On the other hand, heights in graphic area forecasts (GFA) and PIREPs are normally stated as height ASL, since terrain heights are variable over the larger area covered. If heights are not ASL in GFAs, this is always highlighted by statements such as “ST CIGS 24 HND ABV GND”.

(b) Reporting of Ceilings

A ceiling is the lesser of the height above ground or water of the base of the lowest layer of cloud covering more than half the sky or the vertical visibility in a surface-based layer which completely obscures the whole sky.

(c) Sky Conditions

Sky conditions are classified in terms of eighths of sky covered [see MET 3.15.3(k)].

1.1.6 Pilot Reports

PIREP

Pilots are urged to volunteer reports of cloud tops, upper cloud layers, cruising level, wind velocity, and other meteorological information which may be significant to safe or comfortable flight conditions. The information is also used by EC meteorologists to confirm or amend aviation weather forecasts. PIREPs less than 1 hr old that contain information considered to be a hazard to aviation are broadcast immediately to aircraft using the affected area and will be included in subsequent scheduled weather broadcasts. PIREPs are also transmitted on the EC communications system under the headings “UACN10” for normal PIREPs and “UACN01” for urgent PIREPs. A suggested format for PIREPs can be found on the back cover of the CFS and the WAS. More information on PIREP is contained in MET 2.0 and 3.17.

AIREP

Meteorological reports (AIREPs) are appended to the routine position reports of some flights as follows:

(a) International Air Carrier aircraft transiting Canadian Domestic FIRs north of 60°N and east of 80°W, and north of 55°N and west of 80°W should use the AIREP format and report routine meteorological observations to Gander Radio at each designated reporting point or line;

(b) All aircraft operating in the Gander Oceanic Area should use the AIREP format and report routine meteorological observations at each designated reporting point or line. The exception is that aircraft cleared on a designated NAT track will give these reports only if the phrase “SEND MET REPORTS” is included in their oceanic clearance.

There are no special requirements for transmitting AIREP with appended meteorological information other than those specified in the ICAO Regional Supplementary Procedures.

1.1.7 Applicable International Civil Aviation Organization (ICAO) and World Meteorological Organization (WMO) Documents

Whereas ICAO determines the standards and recommended practices with respect to meteorological service for international air navigation, the WMO determines and reports the internationally agreed upon code formats for the reports and forecasts. ICAO and WMO documents applicable to aviation meteorology are as follows:

ICAO Annex 3 – Meteorological Service for International Air Navigation
ICAO Doc 7030 – Regional Supplementary Procedures
ICAO Doc 8755 – Air Navigation Plan – North Atlantic, North American and Pacific Regions
WMO Doc 306 – Manual on Codes

WMO documents may be ordered directly from the WMO Secretariat, Geneva, Switzerland, or from the American Meteorological Society, Boston, Massachusetts. ICAO documents may be purchased from the ICAO Headquarters in Montréal. The two relevant addresses are listed below:

Pilots flying outside of North America should consult the differences filed by other member states as outlined in WMO Doc. 306 or in the AIP of each country

1.1.8 Differences from ICAO Annex 3

CAR 804.01(1)(a) incorporates standards contained in ICAO’s Annex 3 to the Convention on International Civil Aviation — Meteorological Service for International Air Navigation. The current version of Annex 3 includes Amendment 75, which became applicable on November 18, 2010, and will remain in effect until November 2013. In accordance with CAR 800.01(2) the incorporation of Annex 3 as a standard includes the differences notified to ICAO by the Government of Canada in respect of the standards specified in that annex. The full details of these State differences are included in the AIP Canada (ICAO), as published and disseminated by NAV CANADA.

1.2 Meteorological Observation and Reports

1.2.1 Aeronautical Meteorological Stations and Offices

The location of meteorological stations and offices is contained in CFS and in MET 3.1.

1.2.2 Type and Frequency of Observations

Aviation routine weather reports (METAR) are coded weather observations that are taken each hour at over 200 aerodrome and other locations in Canada. In addition, special weather reports (SPECI) are issued whenever weather conditions fluctuate about or are below specified criteria. See MET MET 3.15.3 for the contents and decode instructions for these reports.

METAR and SPECI are taken 24 hours per day at all international aerodromes.

The location of transmissometers or forward scatter sensors used to determine Runway Visual Range is specified in the CAP aerodrome Charts.

Information is available to ATS unit(s) by connections to the EC communications system. Current information with respect to surface wind, Runway Visual Range and altimeter setting is provided by the Operational Information Display System and the Digital Altimeter Display System. At locations where these facilities are not available, altimeter setting indicators and duplicate read-outs of surface wind speed and direction are provided.

1.2.3 Flight Weather Documentation

Pilots must ensure that all weather information used for flight-planning purposes is the most recent information available, and must be aware of when more routinely scheduled weather updates will become available. Pilots must also remain vigilant for pertinent unscheduled weather updates or amendments.

Flight weather documentation is provided in the form of copies of aviation area forecasts, in chart form, together with copies of alphanumeric aerodrome forecasts, and upper wind and temperature forecasts.

1.2.4 Automated Weather Observation System

An automated weather observation system (AWOS) comprises a set of meteorological sensors, a data processing system, a communications system and an optional voice generator module (VGM) and VHF transmitter. AWOS collects meteorological data and disseminates METARs and SPECIs.

Any AWOS that is used for civil aviation purposes must either be the EC-developed system or a commercial AWOS that has been approved by TC for aviation use.

At a minimum, an aviation-approved AWOS is equipped with sensors to report the following:

• wind (direction, speed and gusts);
• altimeter setting (these sensors have a fail-safe design);
• air temperature;
• dew point;
• visibility;
• cloud height;
• sky coverage (of detected cloud);
• precipitation occurrence and type;
• total precipitation;
• and icing.

NOTE: For a complete explanation of the weather reports that are disseminated by AWOS units, please refer to MET 3.15.5.

1.2.5 Limited Weather Information System (LWIS)

A LWIS comprises a subset of the usual automated meteorological sensors, a data processing system, a communication system and optional voice generator module (VGM) and VHF transmitter. LWIS collects limited meteorological data that is transmitted from the site hourly to ATS facilities or every minute to the affiliated VGM and VHF transmitter unit.

Any LWIS used for civil aviation purposes has been approved by TC for aviation use. An aviation-approved LWIS is equipped with sensors to report the following:

• wind (direction, speed and gusts);
• altimeter setting (these sensors have a fail-safe design);
• air temperature; and
• dew point.

1.3 Meteorological Forecasts and Charts

1.3.1 Locations

The location and indicators are listed in CFS and in MET 3.0.

1.3.2 Hours of Service and Telephone Numbers of FICs

All FICs provide 24-hour service. Telephone numbers of FICs are provided in the CFS. Pilots dialing the common toll-free number 1-866-WXBRIEF (992-7433) will automatically be routed to the FIC serving the area from which the call is being made.

Aviation area forecasts are available at all regular international aerodromes for Continental United States excluding Alaska, air routes from North America to Europe, Canada and the Arctic Ocean, air routes between North America and the Caribbean, air routes from the west coast of North America to Japan, and air routes from the west coast of North America to Hawaii.

1.3.4 Aerodrome Forecasts

Aerodrome forecasts (TAF) are prepared for approximately 180 aerodromes across Canada (see MET 3.8). TAFs are limited to aerodromes for which METAR and SPECI reports are available. The forecasts are generally prepared four times daily with periods of validity up to a maximum of 30 hr. See MET 3.9 for more information on TAFs, including when they are issued, their periods of validity and decoding instructions.

TAFs are issued in TAF code, with amendments as required.

Aerodrome Advisory Forecasts

Aerodrome advisories are issued in the place of full TAFs when:

(a) Offsite: the forecast is based on observations that have been taken offsite and are not considered to be representative of weather conditions at the aerodrome;

(b) Observation Incomplete: the forecast is based on observations which have regularly-missing or incomplete data; or

(c) No Specials: the forecast is based on observations from a station with a limited observing program that does not issue SPECI reports.

In each case, after the period of coverage group, the advisory forecast will be labelled with the word “ADVISORY” and the appropriate qualifier (OFFSITE, OBS INCOMPLETE, or NO SPECI).

1.3.5 Weather Information

(a) PATWAS

To serve identified, repetitive information demands, a continuous recording of some local aviation weather information from selected FSSs is accessible by telephone. The locations of this service are identified in CFS and WAS. PATWAS recordings will normally include:

(i) location indicator and introduction,

(ii) instructions,

(iii) SIGMET,

(iv) AIRMETs,

(v) METAR and SPECI reports for selected stations,

(vi) aerodrome forecasts (TAF) for selected stations,

(vii) forecast winds and temperatures aloft (FD),

(viii) icing, freezing level and turbulence,

(x) selected PIREPs, and

(xi) daily sunrise and sunset times.

Portions of the PATWAS recording are typically accessed by using an appropriate touch-tone number once a telephone connection to the system has been made. At the present time, PATWAS recordings must be manually updated; they may not, therefore, reflect the most current weather information available if conditions are changing rapidly.

(b) Coastal Weather

Float plane operators can also obtain coastal marine weather on HF and VHF-FM frequencies from some Canadian Coast Guard stations. Frequencies and time of broadcast are contained in two Canadian Coast Guard Publications – Radio Aids to Marine Navigation (Pacific, and Atlantic and Great Lakes). These two publications are published annually and are available from the Canada Communication Group – Publishing (see MAP 7.2 for addresses and prices).

1.3.6 Area Forecasts and AIRMET

Graphic area forecasts (GFA) are issued as a series of temporally adjusted weather charts for Canadian Domestic Airspace and distributed on a routine or on-request basis. These forecasts are prepared four times daily for 7 regions across the country with a coverage period of 12 hours and an outlook for a further 12 hours. See MET 3.3 for issue, periods of coverage and decoding instructions. Amendments to area forecasts are known as AIRMETs. A full description of this product can be found in MET 3.4.

1.3.7 Upper Level Wind and Temperature Forecasts

Alphanumeric upper level wind and temperature forecasts (FD) are routinely prepared for 142 sites in Canada. FD forecasts are produced by a super-computer model of the atmosphere called a Numerical Weather Prediction (NWP) model (NWP model for short), which is run twice per day (00Z, and 12Z) after ingesting weather observation data from around the world.

An FD forecast based on the 12Z NWP model run on the fifth day of the month would include the following text at the top of the forecast data, “FCST BASED ON 051200 DATA”. The text “DATA VALID 060000” in the FD forecast indicates that the temperature and wind velocity data is forecast to be most representative of conditions at 00Z on the sixth day of the month. FD forecast data can be used for several hours either side of the stated valid time. This is indicated by the text “FOR USE 21 – 06”, which means that this particular forecast may be used for a 9-hour period from 21Z to 06Z.

During flight planning, care must be exercised to ensure that the correct FD forecast is selected and the associated “FOR USE” coverage is appropriate for the time of the proposed flight.

1.3.8 ATC Weather Assistance

ATC will issue information on significant weather and assist pilots in avoiding weather areas when requested. However, for reasons of safety, an IFR flight must not deviate from an assigned course or altitude/flight level without a proper ATC clearance. When weather conditions encountered are so severe that an immediate deviation is determined to be necessary, and time will not permit approval by ATC, the pilot’s emergency authority may be exercised. However, when such action is taken, ATC should be advised as soon as practicable of the flight alteration.

When a pilot requests clearance for a route deviation or for an ATC radar vector, the controller must evaluate the air traffic situation in the affected area and co-ordinate with other controllers before replying to the request when ATC operational boundaries have to be crossed.

It should be remembered that the controller’s primary function is to provide safe separation between aircraft. Any additional service, such as weather avoidance assistance, can only be provided to the extent that it does not detract from the primary function. Also note that the separation workload for the controller generally increases when weather disrupts the usual flow of traffic. ATC radar limitations and frequency congestion is also a factor in limiting the controller’s capability to provide additional services.

It is important, therefore, that the request for a deviation or radar vector be forwarded to ATC as far in advance as possible. Delay in submitting it may delay or even preclude ATC approval or require that additional restrictions be placed on the clearance. Pilots should respond to a weather advisory by requesting: a deviation off course and stating the estimated number of miles and the direction of the requested deviation; a new route to avoid the affected area; a change of altitude; or, radar vectors around the affected areas.

The following information should be given to ATC as early as possible when requesting clearance to detour around weather activity:

(a) proposed route and extent of detour (direction and distance);

(b) flight conditions IMC or VMC; and

(c) advise if the aircraft is equipped with a functioning cockpit weather radar.

The assistance that might be given by ATC will depend upon the weather information available to controllers. Owing to the often transitory nature of severe weather situations, the controller’s weather information may be of only limited value if based on weather observed on radar only. Frequent updates by pilots, giving specific information as to the area affected, altitudes, intensity and nature of the severe weather, are of considerable value. Such PIREPs receive immediate and widespread dissemination to aircrew, dispatchers and aviation forecasters.

1.3.9 Supplementary Information

Weather Radar

Weather radars typically present a display of precipitation within 150 NM of the facility site; storms of considerable height and intensity can be seen at greater ranges. However, it should be noted that these radars cannot detect turbulence. The turbulence associated with a very heavy rate of rainfall will generally be significantly more severe than that associated with light rainfall.

Environment Canada (EC) and the Department of National Defence (DND) operate a series of weather radars across Canada that provide frequent reports of precipitation echo tops and precipitation reflectivity. Radar images are updated approximately every 10 min for individual radars. A colour composite radar product, which depicts either echo tops or precipitation reflectivity is also available on the flight planning section of NAV CANADA’s Web site. The colour composite is not a real-time depiction as the product is 40 min old when issued and is only updated every 40 min.

1.4 VOLMET

1.4.1 General

Information on VOLMET broadcasts is given in the CFS, Section "D", Radio Navigation and Communications.

 

Date modified:

2012-03-29

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