information. The FAA has determined that operators and pilots may utilize the following approved sources of aviation weather information: 

1. 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 observa- tions; for example, contract towers and airport operators may be approved by the Feder al Government to provide weather observations. 

2. Enhanced Weather Information System (EWINS).  An EWINS is an FAA authorized, proprietary system for tracking, evaluating, report- ing, and forecasting the presence or lack of adverse weather phenomena. The FAA authorizes a certifi- cate 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. 

3. Commercial Weather Information Providers.  In general, commercial providers pro- duce 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 propri- etary weather products that substantially alter the information contained in government − produced products. However, those proprietary weather products that substantially alter government − pro- duced 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. 

## NOTE − 

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. 

## 7 − 1 − 4. Graphical Forecasts for Aviation (GFA) 

a. The GFA website is intended to provide the necessary aviation weather information to give users a complete picture of the weather that may affect flight in the continental United States (CONUS). The website includes observational data, forecasts, and warnings that can be viewed from 14 hours in the past to 15 hours in the future, including thunderstorms, clouds, flight category, precipitation, icing, turbu- lence, and wind. Hourly model data and forecasts, including information on clouds, flight category, precipitation, icing, turbulence, wind, and graphical output from the National Weather Service’s (NWS) National Digital Forecast Data (NDFD) are available. Wind, icing, and turbulence forecasts are available in 3,000 ft increments from the surface up to 30,000 ft MSL, and in 6,000 ft increments from 30,000 ft MSL to 48,000 ft MSL. Turbulence forecasts are also broken into low (below 18,000 ft MSL) and high (at or above 18,000 ft MSL) graphics. A maximum icing graphic and maximum wind velocity graphic (regardless of altitude) are also available. Built with modern geospatial information tools, users can pan and zoom to focus on areas of greatest interest. Target users are commercial and general aviation pilots, operators, briefers, and dispatchers. 

## b. Weather Products. 

1. The Aviation Forecasts include gridded displays of various weather parameters as well as NWS textual weather observations, forecasts, and warnings. Icing, turbulence, and wind gridded products are three − dimensional. Other gridded products are two − dimensional and may represent a “composite” of a three − dimensional weather phe- nomenon or a surface weather variable, such as horizontal visibility. The following are examples of aviation forecasts depicted on the GFA: 

(a) Terminal Aerodrome Forecast (TAF) 

(b) Ceiling & Visibility (CIG/VIS) 

(c) Clouds 

(d) Precipitation / Weather (PCPN/WX) 

(e) Thunderstorm (TS) 

(f) Winds 

(g) Turbulence 

(h) Ice 

