Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014) Table 1-1. FIS-B Over UAT Product Update and Transmission Intervals Product FIS-B Over UAT Service Update Intervals1 FIS-B Service Transmission Intervals2 AIRMET As available 5 minutes Convective SIGMET As available 5 minutes METARs / SPECIs 1 minute / as available 5 minutes NEXRAD Composite Reflectivity (CONUS) 15 minutes 15 minutes NEXRAD Composite Reflectivity (Regional) 5 minutes 2.5 minutes NOTAMs-D/FDC/TFR As available 10 minutes PIREP As available 10 minutes SIGMET As available 5 minutes Special Use Airspace Status As available 10 minutes TAF/AMEND 8 hours/as available 10 minutes Temperature Aloft 12 hours 10 minutes Winds Aloft 12 hours 10 minutes 1 The Update Interval is the rate at which the product data is available from the source.
2 The Transmission Interval is the amount of time within which a new or updated product transmission must be completed and the rate or repetition interval at which the product is rebroadcast.
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Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014) Table 1-2. Product Parameters for Low/Medium/High Altitude Tier Radios Product Surface Radios Low Altitude Tier Medium Altitude Tier High Altitude Tier
CONUS NEXRAD N/A CONUS NEXRAD not provided CONUS NEXRAD imagery CONUS NEXRAD imagery Winds & Temps Aloft 500 NM look-ahead range 500 NM look-ahead range 750 NM look-ahead range 1,000 NM look-ahead range METAR 100 NM look-ahead range 250 NM look-ahead range 375 NM look-ahead range CONUS: CONUS Class B & C airport METARs and 500 NM look-ahead range Outside of CONUS: 500 NM look-ahead range TAF 100 NM look-ahead range 250 NM look-ahead range 375 NM look-ahead range CONUS: CONUS Class B & C airport TAFs and 500 NM look-ahead range Outside of CONUS: 500 NM look-ahead range
AIRMET, SIGMET, PIREP, and Special Use Airspace / SAA 100 NM look-ahead range.
PIREP/SUA is N/A 250 NM look-ahead Range 375 NM look-ahead range 500 NM look-ahead range Regional NEXRAD 150 NM look-ahead range 150 NM look-ahead range 200 NM look-ahead range 250 NM look-ahead range NOTAMs D, FDC, TFR 100 NM look-ahead range 100 NM look-ahead range 100 NM look-ahead range 100 NM look-ahead range Users should obtain guidance concerning the content, format, and symbology of individual FIS-B products from the manufacturer of the avionics equipment used to receive and display them.
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Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014)
1.3.7.2 Operational Use of FIS-B Products FIS-B products are intended to enhance the user’s situational awareness and enable more efficient use of ATC/FSS/AOCC services. The information provided by FIS-B is advisory in nature and should not be used in lieu of individual pre-flight, in-flight, weather, or flight planning briefings provided by ATC/FSS/AOCC services.
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Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014) 2 AVIATION WEATHER PRODUCT POLICY The demand for new and improved aviation weather products continues to grow and, with new products introduced to meet the demand, some confusion has resulted in the aviation community regarding the relationship between regulatory requirements and the new weather products.
This section will clarify that relationship by providing:
• P olicy guidance for using aviation weather products,
• D escriptions of the types of aviation weather information, and
• Ca tegorization of the sources of aviation weather information.
2.1 Use of Aviation Weather Products With increased access to these weather products via the public Internet, the aviation community has access to an overwhelming amount of weather information and data that support self-briefing. This advisory circular (AC) describes the weather products distributed by the National Weather Service (NWS). Pilots and operators using the public Internet to access weather from a third-party vendor should request and/or review an appropriate description of services and provider disclosure. This should include, but is not limited to, the type of weather product (e.g., current weather or forecast weather), the currency of the product (i.e., product issue and valid times), and the relevance of the product. Pilots and operators should be cautious when using unfamiliar weather products and when in doubt, consult with a Flight Service Specialist.
The development of new weather products, coupled with the termination of some legacy textual and graphical products may create confusion between regulatory requirements and the new products. All flight-related aviation weather decisions must be based on all available pertinent weather products. As every flight is unique and the weather conditions for that flight vary hour by hour, day to day, multiple weather products may be necessary to meet aviation weather regulatory requirements. Many new weather products now have a Precautionary Use Statement that details the proper use or application of the specific product.
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Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014)
2.2 Types of Aviation Weather Information The Federal Aviation Administration (FAA) has identified the following three distinct types of weather information that may be needed to conduct aircraft operations: observations, analyses, and forecasts.
2.2.1 Observations Observations are raw weather data collected by some type of sensor(s). The observations can either be in situ (e.g., surface or airborne) or remote (e.g., weather radar, satellite, profiler, and lightning).
2.2.2 Analysis Analyses of weather information are an enhanced depiction and/or interpretation of observed weather data.
2.2.3 Forecasts Forecasts are the predictions of the development and/or movement of weather phenomena based on meteorological observations and various mathematical models.
In-flight weather advisories, including Significant Meteorological Information (SIGMET), Convective SIGMETs, Airman’s Meteorological Information (AIRMET), Center Weather Advisories (CWA), and Meteorological Impact Statements (MIS), are considered forecast weather information products.
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Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014)
2.3 Categorizing Aviation Weather Sources The regulations pertaining to aviation weather reflect that, historically, the Federal Government was the only source of aviation weather information. That is, the FAA and NWS, or its predecessor organizations, were solely responsible for the collection and dissemination of weather data, including forecasts. Thus, the term “approved source(s)” referred exclusively to the Federal Government. The Federal Government is no longer the only source of weather information, due to the growing sophistication of aviation operations and scientific and technological advances.
Since all three types of weather information defined in paragraph 2.2 are not available from all sources of aviation weather information, the FAA has categorized the sources as follows: Federal Government, Enhanced Weather Information System (EWINS), and commercial weather information providers.
2.3.1 Federal Government The FAA and NWS collect weather observations. The NWS analyzes the observations, and produces forecasts, including in-flight aviation weather advisories (e.g., SIGMETs). The FAA and NWS disseminate meteorological observations, analyses, and forecast products through a variety of systems. The Federal Government is the only approval authority for sources of weather observations (e.g., contract towers and airport operators).
Commercial weather information providers contracted by the FAA to provide weather observations
(e.g., contract towers, Lockheed Martin, Direct Use Access Terminal Service (DUAT/DUATS) are included in the Federal Government category of approved sources by virtue of maintaining required technical and quality assurance standards under FAA and NWS oversight.
2.3.2 Enhanced Weather Information System (EWINS) An EWINS is a system for gathering, evaluating, and disseminating aviation weather information, and for issuing weather reports and forecasts prepared by properly trained and qualified aviation meteorologists or aircraft dispatchers. Air carriers use EWINS, which are proprietary to each carrier.
In order to use an EWINS, each air carrier requires FAA approval.
To receive FAA approval, each carrier’s EWINS must have sufficient procedures, personnel, and communications and data processing equipment to effectively obtain, analyze, and disseminate aeronautical weather data. For a full explanation of the requirements for EWINS approval, see the Flight Standards Information Management System (FSIMS), Order 8900.1, Volume 3, Chapter 26, Section 4, Enhanced Weather Information Systems. An EWINS source may produce weather analyses and forecasts based on meteorological observations provided by the Federal Government. Approval to use EWINS weather products is issued on a case-by-case basis and is currently only applicable to Title 14 of the Code of Federal Regulations (14 CFR) part 91K Program Managers and 14 CFR part 121/135 certificate holders, who may either act as their own EWINS or contract those services from a separate entity. These approved operators may conduct flight operations using the weather analyses and forecasts produced by their approved EWINS.
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Aviation Weather Services, Advisory Circular 00-45G Change 2 (October 2014)
2.3.3 Commercial Weather Information Providers Commercial weather providers are a major source of weather products for the aviation community.
In general, they produce proprietary weather products based on NWS products with formatting and layout modifications but no material changes to the weather information itself. This is also referred to as “repackaging.”
Commercial providers may also produce forecasts, analyses, and other proprietary weather products and substantially alter the information contained in NWS-produced products. Operators who desire to use products prepared by a commercial weather provider as opposed to using products that are simply repackaged, may require FAA approval to use an EWINS. For more information on whether an EWINS is required to use products prepared by a commercial weather provider, refer to FSIMS, Order 8900.1, Volume 3, Chapter 26, Section 2, Regulatory Sources of Aviation Weather Information. Operators and pilots contemplating using such services should request and/or review an appropriate description of services and provider disclosure. This should include, but is not limited to:
• The type of weather product (e.g., current weather or forecast weather),
• The currency of the product (i.e., product issue and valid times), and
• The relevance of the product.
Pilots and operators should be cautious when using unfamiliar products, or products not supported by FAA/NWS technical specifications.
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Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010) 3 OBSERVED TEXT PRODUCTS
3.1 Aviation Routine Weather Reports (METAR) and Aviation Selected Special Weather Reports (SPECI) Surface weather observations are fundamental to all meteorological services. Observations are the basic information upon which forecasts and warnings are made in support of a wide range of weather sensitive activities within the public and private sectors, including aviation.
Although the METAR/SPECI code is used worldwide, each country is allowed to make modifications or exceptions to the code for use in their particular country. This section will focus on the U.S. modifications and exceptions. METAR/SPECIs are available online at:
http://adds.aviationweather.gov/metars/
3.1.1 Aviation Routine Weather Report (METAR) Aviation Routine Weather Report (METAR) is the primary observation code used in the U. S. to satisfy World Meteorological Organization (WMO) and International Civil Aviation Organization (ICAO) requirements for reporting surface meteorological data. A METAR report includes the airport identifier, time of observation, wind, visibility, runway visual range, present weather phenomena, sky conditions, temperature, dew point, and altimeter setting. Excluding the airport identifier and the time of observation, this information is collectively referred to as “the body of the report.” As an addition, coded and/or plain language information elaborating on data in “the body of the report” may be appended to the end of the METAR in a section coded as “Remarks.” The contents of the “Remarks” section vary with the type of reporting station. The METAR may be abridged at some designated stations only including a few of the mentioned elements.
3.1.2 Aviation Selected Special Weather Report (SPECI) An Aviation Selected Special Weather Report (SPECI) is an unscheduled report taken when any of the criteria given in Table 3-1 are observed during the interim period between the hourly reports. SPECI contains all data elements found in a METAR plus additional plain language information which elaborates on data in the body of the report. All SPECIs are made as soon as possible after the relevant criteria are observed.
Whenever SPECI criteria are met at the time of the routine METAR, a METAR is issued.
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Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010)
Table 3-1. SPECI Criteria 1 Wind Shift Wind direction changes by 45 degrees or more in less than 15 minutes and the wind speed is 10 knots or more throughout the wind shift.
2 Visibility Surface visibility as reported in the body of the report decreases to less than, or if below, increases to equal or exceed:
a. 3 miles
b. 2 miles
c. 1 mile
d. The lowest standard instrument approach procedure minimum as published in the National Ocean Service (NOS) U.S Instrument Procedures. If none published use ½ mile.
3 Runway Visual Range (RVR) The highest value from the designated RVR runway decreases to less than, or if below, increases to equal or exceed 2,400 feet during the preceding 10 minutes.
U.S. military stations may not report a SPECI based on RVR.
4 Tornado, Funnel Cloud, or Waterspout
a. is observed.
b. disappears from sight, or ends.
5 Thunderstorm a. begins (a SPECI is not required to report the beginning of a new thunderstorm if one is currently reported).
b. ends.
6 Precipitation a. hail begins or ends.
b. freezing precipitation begins, ends, or changes intensity.
c. ice pellets begin, end, or change intensity 7 Squalls When they occur 8 Ceiling The ceiling (rounded off to reportable values) forms or dissipates below, decreases to less than, or if below, increases to equal or exceed:
a. 3,000 feet.
b. 1,500 feet
c. 1,000 feet
d. 500 feet
e. The lowest standard instrument approach procedure minimum as published in the National Ocean Service (NOS) U.S Instrument Procedures. If none published, use 200 feet.
9 Sky Condition A layer of clouds or obscurations aloft is present below 1,000 feet and no layer aloft was reported below 1,000 feet in the preceding METAR or SPECI.
10 Volcanic Eruption When an eruption is first noted 11 Aircraft Mishap Upon notification of an aircraft mishap, unless there has been an intervening observation 12 Miscellaneous Any other meteorological situation designated by the responsible agency of which, in the opinion of the observer, is critical.
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Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010)
3.1.3 Format
Figure 3-1. METAR/SPECI Coding Format
A METAR/SPECI (Figure 3-1) has two major sections: the Body (consisting of a maximum of 11 groups) and the Remarks (consisting of 2 categories). Together, the body and remarks make up the complete METAR/SPECI. When an element does not occur, or cannot be observed, the corresponding group is omitted from that particular report.
3.1.3.1 Type of Report
METAR KOKC 011955Z AUTO 22015G25KT 180V250 3/4SM R17L/2600FT +TSRA BR OVC010CB 18/16 A2992 RMK AO2 TSB25 TS OHD MOV E SLP132
The type of report, METAR or SPECI precedes the body of all reports.
3.1.3.2 Station Identifier
METAR KOKC 011955Z AUTO 22015G25KT 180V250 3/4SM R17L/2600FT +TSRA BR OVC010CB 18/16 A2992 RMK AO2 TSB25 TS OHD MOV E SLP132
The station identifier, in ICAO format, is included in all reports to identify the station to which the coded report applies.
The ICAO airport code is a four-letter alphanumeric code designating each airport around the world. The ICAO codes are used for flight planning by air traffic controllers and airline operation departments. These codes are not the same as the International Air Transport Association (IATA) codes encountered by the general public used for reservations, baggage handling and in airline timetables. ICAO codes are also used to identify weather stations located on- or offairport.
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Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010) Unlike the IATA codes, the ICAO codes have a regional structure. For example, the first letter is allocated by continent (Figure 3-2), the second is a country within the continent; the remaining two are used to identify each airport.
90N180 165W 150W 135W 120W 105W 90W 7SW 60W 45W 30W 90E 105E 120E 135E 150E 165E 180 90N 75N 75N 60N - 60N 45N 45N 30N 30N 15N - 15N e155 30S- 30S 45Sk ··455 60S 60S 755 180 75S 165W 150W 135W 120W 105W 90W 75 W 60W 45W 30W 15E 30E 45E 60E 90E 105E 120E 135E 150E 165E 180 Figure 3-2. ICAO Continent Codes In the contiguous U.S., ICAO station identifiers are coded K followed by the three-letter IATA identifier. For example, the Seattle, Washington (IATA identifier SEA) becomes the ICAO identifier KSEA.
ICAO station identifiers in Alaska, Hawaii, and Guam begin with the continent code P, followed by the proper country code (A, H, and G respectively), and the two-letter airport identifier.
Examples:
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Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010) PANC Anchorage, AK PAOM Nome, AK PHNL Honolulu, HI PHKO Keahole Point, HI PGUM Agana, Guam PGUA Anderson AFB, Guam
Canadian station identifiers begin with C, followed by the country code, and the two-letter airport identifier.
Examples:
CYYZ Toronto, Canada CYYC Calgary Canada CYQB Quebec, Canada CYXU London, Canada CZUM Churchill Falls, Canada
Mexican and western Caribbean station identifiers begin with M, followed by the proper country code and two-letter airport identifier.
Examples:
MMMX Mexico City, Mexico MUGM Guantanamo Bay, Cuba MDSD Santo Domingo, Dominican Republic MYNN Nassau, Bahamas
Eastern Caribbean station identifiers begin with T, followed by the proper country code, and airport identifier.
Examples:
TJSJ San Juan, Puerto Rico TIST Saint Thomas, Virgin Islands
For a list of Alaskan, Hawaiian, Canadian, Mexican, Pacific, and Caribbean ICAO identifiers see FAA Order 7350.7. For a complete worldwide listing, see ICAO Document 7910, “Location Indicators.” Both are available on-line.
3.1.3.3 Date and Time of Report
METAR KOKC 011955Z AUTO 22015G25KT 180V250 3/4SM R17L/2600FT +TSRA BR OVC010CB 18/16 A2992 RMK AO2 TSB25 TS OHD MOV E SLP132
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