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• Icing;
• Graphical AIRMETs (G-AIRMET); and
• CWA.
Users of FIS-B should familiarize themselves with the operational characteristics and limitations of the system, including: system architecture, service environment, product lifecycles, modes of operation, and indications of system failure.
Up date intervals are defined as the rate at which the product data is available from the source for transmission. Transmission intervals are defined as the amount of time within which a new or updated product transmission must be completed and/or the rate or repetition interval at which the product is rebroadcast. Table 1-1, FIS-B Over UAT Product Update and Transmission Intervals, provides update and transmission intervals for each product.
Where applicable, FIS-B products include a look-ahead range expressed in nautical miles for three service domains: Airport Surface, Terminal Airspace, and En route/Gulf of Mexico. Table 1-2, Product Parameters for Low/Medium/High Altitude Tier Radios, provides service domain availability and look-ahe ad ranging for each FIS-B product.
Prior to using this capability, users should familiarize themselves with the operation of FIS-B avionics by referencing the applicable user’s guides. Users should obtain guidance concerning the interpretation of information displayed from the appropriate avionics manufacturer.
Us ers should report FIS-B malfunctions not attributed to aircraft system failures or covered by active NOTAM via the ADS-B/Traffic Information Services-Broadcast (TIS-B)/FIS-B Problem Report on the following website:
http://www.faa.gov/exit/?pageName=this%20form&pgLnk=http%3A%2F%2Fgoo%2Egl %2Fforms%2FisWDKYpYYv. Users may also report malfunctions by submitting FAA Form 8740-5, Safety Improvement Report, via mail, fax, or email to your local F light District Standards Office (FSDO) Safety Program Manager (SPM).
1-11 Table 1-1. FIS-B Over UAT Product Update and Transmission Intervals Product FIS-B Over UAT Service Update Interval1 FIS-B Service Transmission Interval2 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 6 hours/as available 10 minutes Temperature Aloft 12 hours 10 minutes Winds Aloft 12 hours 10 minutes Lightning Strikes 5 minutes 5 minutes Turbulence 15 minutes 15 minutes Icing Forecasts 15 minutes 15 minutes Cloud Tops 15 minutes 15 minutes Graphical AIRMETS 00Z,03Z, 06Z, 09Z/12 hr forecasts 3 hour Center Weather Advisories As available As available
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.
3. Notice to Airmen-Distant (NOTAM-D) and Notice to Airmen-Flight Data Center (NOTAM-FDC) products broadcast via FIS-B are limited to those issued or effective within the past 30 days.
1-12 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 Lightning Strikes N/A 150 NM look-ahead range 200 NM look-ahead range 250 NM look-ahead range Turbulence N/A 150 NM look-ahead range 200 NM look-ahead range 250 NM look-ahead range Icing Forecasts N/A 150 NM look-ahead range 200 NM look-ahead range 250 NM look-ahead range Cloud Tops N/A 150 NM look-ahead range 200 NM look-ahead range 250 NM look-ahead range Graphical AIRMETS N/A 250 NM look-ahead range 375 NM look-ahead range 500 NM look-ahead range Center Weather Advisories N/A 250 NM look-ahead range 375 NM look-ahead range 500 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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1.3.5 Operational Use of FIS-B Products.
FIS-B information may be used by the pilot for the safe conduct of flight and aircraft movement. However, FIS-B does not replace a thorough preflight briefing that may be from one or several Meteorological Information and AI sources. Pilots are encouraged, but not required, to use the dispatch/System Operations Control (SOC) (if applicable), or access an FSS via telephone. Title 14 CFR part 91, § 91.103 requires the pilot in command (PIC) to be familiar with all available information concerning that flight. A pil ot should be particularly alert and understand the limitations and quality assurance (QA) issues associated with individual products. This includes graphical representation of NEXRAD imagery and NOTAM/TFR.
2-1 CHAPTER 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 new weather products.
This chapter will clarify that relationship by providing:
• Policy guidance for using aviation weather products,
• Descriptions of the types of aviation weather information, and
• Categorization of the sources of aviation weather information.
2.1 Use of Aviation Weather Products.
This AC describes the weather products distributed by the NWS. Pilots and operators using the 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 (i.e., current weather or forecasted 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. When in doubt, consult with a Flight Service Specialist.
Note that the FAA does not approve or qualify Internet providers of aviation weather service.
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 have a precautionary use statement displayed that details the proper use or application of the specific product.
2.2 Types of Aviation Weather Information.
The 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 sensor(s). The observations can either be in situ (i.e., surface or airborne) or remote (i.e., weather radar, satellite, profiler, and lightning).
2.2.2 Analyses.
Analyses of weather information are an enhanced depiction and/or interpretation of observed weather data. Examples of these types of analyses can be seen in paragraph 4.1.1. Another type of analysis is the representation of an atmospheric variable
(e.g., temperature, ceiling height, and visibility) derived from a finite set of irregularly
2-2 dis tributed observations onto a regular grid. See the figures in paragraph 4.2 for examples.
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 Terminal Aerodrome Forecast (TAF), 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.
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 their 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.
Si nce 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 fol lows: Federal Government 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 and Lockheed Martin) 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.
2.4 Commercial Weather Information Providers.
Commercial weather information providers are a major source of weather products for the aviation community. In general, they produce proprietary weather products based on NWS information with formatting and layout modifications, but no material changes to the weather information itself. This is also referred to as “repackaging.”
In other cases, commercial providers produce forecasts, analyses, and other proprietary weather products which may substantially differ from 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. This approval is granted under the provisions in Operations Specification
2-3 (OpSpec) paragraph A010. Please provide which services and products you are contemplating using, to include the appropriate description of the service. 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.
3-1 CHAPTER 3. OBSERVATIONS The first of three distinct types of weather (meteorological) information is observations.
Observations are weather data collected by one or more sensors, and are the basic information upon which forecasts and advisories are made in support of a wide range of weather-sensitive activities within the public and private sectors, including aviation. Chapter 3 describes and discusses surface observations, aircraft observations, radar observations, and satellite observations (e.g., imagery).
3.1 Aviation Routine Weather Reports (METAR) and Special Weather Reports (SPECI).
Surface weather observations are fundamental to all meteorological services. Aviators typically view surface observations through METARs and SPECIs. Although the METAR/SPECI code is used worldwide, there are some code differences among countries. Each country is allowed to make modifications to the code for use in their particular country, as long as they notify the International Civil Aviation Organization (ICAO). These paragraphs will focus on the METAR/SPECI code as used in the United States.
3.1.1 Aviation Routine Weather Report (METAR).
The METAR report has been adopted by the United States to provide surface observations in support of aviation for the terminal. A METAR report includes the airport identifier, time of observation, wind, visibility, Runway Visual Range (RVR), present weather phenomena, sky conditions, temperature, dewpoint, and altimeter setting.
Excluding the airport identifier and the time of observation, this information is collectively referred to as the “body” of the report. Coded and/or plain language information elaborating on data in the body may be appended to the end of the METAR as “remarks.” The contents of the remarks section varies with the type of reporting station. At some designated stations, the METAR may be abridged to include only a few of the mentioned elements.
3.1.2 Special Weather Report (SPECI).
A SPECI is an unscheduled report taken when any of the criteria given in Table 3-1, SPECI Criteria, are observed during the period between hourly reports. SPECIs contain al l data elements found in a METAR. All SPECIs are issued as soon as possible when relevant criteria are observed.
Whenever SPECI criteria are met at the time of the routine METAR, a METAR is issued.
3-2 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 to or exceeding:
• miles
• mile s
• 1 mile
• The lowest standard instrument approach procedure minimum as published in the Nat ional 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 to or exceeding 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 • Is observed • Disappears from sight, or ends 5 Thunderstorm
• Begins (a SPECI is not required to report the beginning of a new thunderstorm if one is currently reported)
• Ends 6 Precipitation
• Hail begins or ends
• Freezing precipitation begins, ends or changes intensity
• Ice pellets begin, end or change intensity 7 Squalls When a squall occurs.
8 Ceiling The ceiling (rounded to reportable values) forms or dissipates below, decreases to less than, or if below, increases to equal to or exceeding:
• 3,000 feet
• 1,5 00 feet
• 1,000 feet
• 500 feet
• The lowest standard instrument approach procedure minimum as published in the Nat ional 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.
The information in Table 3-1 can be found in the Federal Meteorological Handbook No. 1 (FMH-1), Section 2.5.2, Aviation Selected Special Weather Report (SPECI).
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3.1.3 General Types of Observations.
There are three general types of surface observations:
• Manual Observation. Weather observations done by a human weather observer who is certified by the FAA.
• A utomated Observation. Automated observations are derived from instruments and algorithms without human input or oversight. In the United States, there are two main kinds of automated observing systems: the automated surface observing system (ASOS) and the Automated Weather Observing System (AWOS). Detailed information on ASOS and AWOS can be found in the Aeronautical Information Manual (AIM), Chapter 7, Safety of Flight, Section 1, Meteorology. Automated METARs and SPE CIs contain AUTO in the report (see paragraph 3.1.5.4).
• Augmented Observation. At select airports in the United States, the automated observing system will have input and oversight by human weather observers or tower controllers certified in weather observing. These are referred to as augmented stations. Human observers report weather elements that are beyond the capabilities of the automated system and/or are deemed operationally significant. The weather elements observed and reported by the human observer vary, depending on the selected airport. AUTO is not used in augmented reports.
Whereas manual stations were most common prior to the mid-1990s in the United States, the vast majority of today’s METARs and SPECIs are from fully-automated stations.
3.1.4 Recency of Observed Elements at Automated Stations.
For those elements that the human observer evaluates using spatial averaging techniques
(e.g., sky cover and visibility), the automated station substitutes time averaging of sensor data. Therefore, in an automated observation, sky condition is an evaluation of sensor data gathered during the 30-minute period ending at the actual time of the observation.
All other elements are based on sensor data that is within 10 minutes or less of the actual time of the observation.
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3.1.5 Format.
Figure 3-1. METAR/SPECI Coding Format
A U.S. METAR/SPECI has two major sections: the body (consisting of a maximum of 11 groups) and the remarks (consisting of 2 categories). When an element does not occur, or cannot be observed, the corresponding group is omitted from that particular report.
3.1.5.1 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, but may not be shown or displayed on all aviation weather websites.
3.1.5.2 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 pilots 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.
3-5 Unlike the IATA codes, the ICAO codes have a regional structure. The first letter identifies the region and country (see Figure 3-2, ICAO Continental Codes). In some regions, the second letter identifies the country. ICAO station identifiers in Alaska begin with PA, Hawaii begins with PH, Guam begins with PG, and Puerto Rico begins with TS. For example, the San Juan Puerto Rico IATA identifier “SJU” becomes the ICAO identifier “TSJU.” The remaining letters are used to identify each airport.
Figure 3-2. ICAO Continental Codes
In the continental United States (CONUS), ICAO station identifiers are coded K, followed by the three-letter IATA identifier. For example, the Seattle, WA IATA identifier SEA becomes the ICAO identifier KSEA.
ICAO station identifiers in Alaska, Hawaii, and Guam begin with the continent code P.
For a list of all U.S. identifiers, refer to FAA Order 7350.9, Location Identifiers. For a complete worldwide listing, refer to ICAO Document 7910, Location Indicators. Both are available online.
3.1.5.3 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