Top

Weather & Atmosphere

Introduction

  • Regardless of your experience level, weather is likely to be a key factor in your decision making process and so a pilot's ability to find and interpret weather is important to making well-informed decisions
  • Weather service to aviation is a joint effort between federal agencies, the military weather services, and other aviation oriented groups and individuals
  • The National Weather Service operates a network of radar sites for detecting coverage, intensity, and movement of precipitation
    • The network is supplemented by FAA and DOD radar sites in the western sections of the country
    • Local warning radar sites augment the network by operating on an as needed basis to support warning and forecast programs
ASA Aviation Weather Services
Figure 1: ASA Aviation Weather Services

Federal Agencies:

  • National Weather Service:

    • Provides weather, water, and climate data, forecasts and warnings for the protection of life and property and enhancement of the national economy
  • The National Oceanic and Atmospheric Administration (NOAA):

    • NOAA conducts research and gathers data about the global oceans, atmosphere, space, and the sun
    • Most importantly to pilots, they maintain the Aviation Digital Data Service (ADDS) which makes text, digital and graphical forecasts, analyses, and observations of aviation-related weather variables available to the aviation community
  • Federal Aviation Administration:

    • The FAA facilitates and oversees the various agencies which create pilot products

Military Weather Services:

  • Services for the military mimic those found within civilian agencies but of course, are tailored to the uniqueness that comes with the military
  • Services include:

Aviation Oriented Groups and Individuals:

  • Lockheed Martin is contracted through the FAA to provide weather services, notably their operation of Flight Service Stations
  • Direct User Access Terminal System (DUATS) provides immediate on-line access to U.S. Federal Aviation Administration (FAA) approved information including:
    • Current, continuously updated weather information
    • Easy-to-understand plain language weather
    • Flight plan filing and closing
    • Automated flight planning

National Weather Service Aviation Products:

  • The NWS maintains an extensive surface, upper air, and radar weather observing program; a nationwide aviation weather forecasting service; and provides limited pilot briefing service (interpretational)
  • Pilot weather briefings are provided by personnel at Flight Service Stations operated by FAA (in Alaska) or by federal contract facilities (elsewhere in the U.S.)
  • Aviation routine weather reports (METAR) are taken manually by NWS, FAA, contractors, or supplemental observers
    • METAR reports are also provided by Automated Weather Observing System (AWOS), Automated Surface Observing System (ASOS), and Automated Weather Sensor System (AWSS)
    • You can learn more by reading AIM 7-1-12
  • Aerodrome forecasts are prepared by 122 Weather Forecast Offices (WFOs)
    • These offices prepare and distribute 625 aerodrome forecasts 4 times daily for specific airports in the 50 States, Puerto Rico, the Caribbean and Pacific Islands
    • These forecasts are valid for 24 or 30 hours and amended as required
    • A centralized aviation forecast program originating from the Aviation Weather Center (AWC) in Kansas City was implemented in October 1995
    • In the conterminous U.S., all inflight advisories, Significant Meteorological Information (SIGMETs), Convective SIGMETs, and Airmen's Meteorological Information (AIRMET-text bulletins [WA] and graphics [G-AIRMETs]), and all Area Forecasts (FAs) (6 areas) are now issued by AWC
    • FAs are prepared 3 times a day in the conterminous U.S. and Alaska (4 times in Hawaii), and amended as required
    • Inflight advisories are issued only when conditions warrant
    • Winds aloft forecasts are provided for 176 locations in the 48 contiguous States and 21 locations in Alaska for flight planning purposes (Winds aloft forecasts for Hawaii are prepared locally)
    • All the aviation weather forecasts are given wide distribution through the Weather Message Switching Center Replacement (WMSCR) in Atlanta, Georgia, and Salt Lake City, Utah
  • Weather element values may be expressed by using different measurement systems depending on several factors, such as whether the weather products will be used by the general public, aviation interests, international services, or a combination of these users
  • Conversion tables, such as [Figure 1] below, are available for pilot use

Use of Aviation Weather Products:

  • Air carriers and operators certificated under the provisions of 14 CFR Part 119 are required to use the aeronautical weather information systems defined in the Operations Specifications issued to that certificate holder by the FAA. These systems may utilize basic FAA/National Weather Service (NWS) weather services, contractor- or operator-proprietary weather services and/or Enhanced Weather Information System (EWINS) when approved in the Operations Specifications
    • As an integral part of this system approval, the procedures for collecting, producing and disseminating aeronautical weather information, as well as the crew member and dispatcher training to support the use of system weather products, must be accepted or approved
  • Operators not certificated under the provisions of 14 CFR Part 119 are encouraged to use FAA/NWS products through Flight Service Stations, DUATS, and/or Flight Information Services-Broadcast (FIS-B)
  • The suite of available aviation weather product types is expanding, with the development of new sensor systems, algorithms and forecast models
    • The FAA and NWS, supported by various weather research laboratories and corporations under contract to the Government, develop and implement new aviation weather product types
    • The FAA's NextGen Aviation Weather Research Program (AWRP) facilitates collaboration between the NWS, the FAA, and various industry and research representatives
    • This collaboration ensures that user needs and technical readiness requirements are met before experimental products mature to operational application
  • The AWRP manages the transfer of aviation weather R&D to operational use through technical review panels and conducting safety assessments to ensure that newly developed aviation weather products meet regulatory requirements and enhance safety
  • The AWRP review and decision-making process applies criteria to weather products at various stages
  • The stages are composed of the following:
    • Sponsorship of user needs
    • R & D and controlled testing
    • Experimental application
    • Operational application
  • Pilots and operators should be aware that weather services provided by entities other than FAA, NWS or their contractors (such as the DUAT/DUATS and Lockheed Martin Flight Services) may not meet FAA/NWS quality control standards
    • Hence, 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
      • When in doubt, consult with a FAA Flight Service Station Specialist
  • In addition, pilots and operators should be aware there are weather services and products available from government organizations beyond the scope of the AWRP process mentioned earlier in this section
    • For example, governmental agencies such as the NWS and the Aviation Weather Center (AWC), or research organizations such as the National Center for Atmospheric Research (NCAR) display weather "model data" and "experimental" products which require training and/or expertise to properly interpret and use
    • These products are developmental prototypes that are subject to ongoing research and can change without notice
    • Therefore, some data on display by government organizations, or government data on display by independent organizations may be unsuitable for flight planning purposes
    • 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 (for example, 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
      • When in doubt, consult with a FAA Flight Service Station Specialist
  • With increased access to weather products via the public Internet, the aviation community has access to an over whelming amount of weather information and data that support self-briefing
    • FAA AC 00-45 (current edition) describes the weather products distributed by the 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 (for example, 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
      • When in doubt, consult with a FAA Flight Service Station 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
  • The FAA has identified three distinct types of weather information available to pilots and operators
  • Conversion Tables
    Figure 1: Conversion Tables
  • Not all sources of aviation weather information are able to provide all three types of weather information. The FAA has determined that operators and pilots may utilize the following approved sources of aviation weather information:
    • Federal Government:

      • The FAA and NWS collect raw weather data, analyze the observations, and produce forecasts. The FAA and NWS disseminate meteorological observations, analyses, and forecasts through a variety of systems. In addition, the Federal Government is the only approval authority for sources of weather observations; for example, contract towers and airport operators may be approved by the Federal Government to provide weather observations
    • Enhanced Weather Information System (EWINS):

      • An EWINS is an FAA authorized, proprietary system for tracking, evaluating, reporting, and forecasting the presence or lack of adverse weather phenomena. The FAA authorizes a certificate holder to use an EWINS to produce flight movement forecasts, adverse weather phenomena forecasts, and other meteorological advisories. For more detailed information regarding EWINS, see the Aviation Weather Services Advisory Circular 00-45 and the Flight Standards Information Management System 8900.1
    • Commercial Weather Information Providers:

      • In general, commercial providers produce proprietary weather products based on NWS/FAA products with formatting and layout modifications but no material changes to the weather information itself. This is also referred to as "repackaging." In addition, commercial providers may produce analyses, forecasts, and other proprietary weather products that substantially alter the information contained in government-produced products. However, those proprietary weather products that substantially alter government− produced weather products or information, may only be approved for use by 14 CFR Part 121 and Part 135 certificate holders if the commercial provider is EWINS qualified
        • Commercial weather information providers contracted by FAA to provide weather observations, analyses, and forecasts (e.g., contract towers) are included in the Federal Government category of approved sources by virtue of maintaining required technical and quality assurance standards under Federal Government oversight
  • As a point of clarification, Advisory Circular 00-62, Internet Communications of Aviation Weather and NOTAMS, describes the process for a weather information provider to become a Qualified Internet Communications Provider (QICP) and only applies to 14 CFR Part 121 and Part 135 certificate holders. Therefore, pilots conducting operations under 14 CFR Part 91 may access weather products via the public Internet

Weather:

References: