Flight Path Tool (version 2) Tutorial


http://weather.aero/java/

    After extensive re-design and consideration of user feedback, the ADDS development team released version 2 of the flagship ADDS Java application, the Flight Path Tool in April 2008. We believe the new tool is significantly improved from prior versions and is the most comprehensive and user-friendly weather visualization software available. Like its predecessor, the Flight Path Tool displays three-dimensional icing, turbulence, winds, temperature, and humidity in horizontal and vertical views. Newly available two-dimensional data include satellite, radar, cloud ceiling, surface visibility, and flight category. The ceiling, surface visibility, and flight category data include a low confidence overlay. Typical forecast and observed textual data including surface weather reports (METARs), terminal forecasts (TAFs), voice and automated pilot reports (PIREPs), and en-route weather advisories (AIRMETs and SIGMETs) that are available to view graphically and/or in text form. Another new feature in this version is the Meteorogram tool that combines past observed weather data (METARs) combined with future prediction (TAFs) in tabular form.

    This tutorial describes the technical aspects to use the software effectively. The regulatory issues related to the use of this experimental software and some experimental weather products are not documented herein and must be consulted (in the Federal Aviation Regulations - Aeronautical Information Manual, AIM). The following topics are covered in subsections below:


 

Weather products

    Weather products in the Flight Path Tool include grids of various weather parameters as well as National Weather Service (NWS) textual weather observations and forecasts. Some gridded products are three-dimensional including temperature, relative humidity, winds, icing, and turbulence. Other gridded products are two-dimensional and may represent a “composite” of a three-dimensional weather phenomenon (for instance the convection product) or a surface weather variable such as horizontal visibility. A description of each gridded product is given below. Also, the tool displays relevant NWS textual weather observations and forecasts needed for aviation. These data are either points of observed or forecast weather, often at airports, or regions of hazardous weather represented by two-dimensional polygons. Each item is briefly mentioned below with more descriptive information found on their respective "FYI/Help" page(s) within ADDS.
    Temperature, relative humidity, and wind speed are available in four-dimensional space and time. These data are taken directly from the Rapid Update Cycle (RUC) numerical model run at NCEP. They update as an analysis every hour and as a 3, 6, 9, and 12-hour forecast every three hours. The RUC data provides the best possible spatial and temporal resolution. Currently the tool only accesses these fields from RUC data, which covers all of the contiguous United States and parts of Mexico/Canada. In the future, with sufficient funding, the development team desires to include global data with forecasts for multiple days into the future.
    The turbulence product combines various weather data sources and numerous turbulence diagnostic metrics into a current analysis and future prediction of upper-level clear-air turbulence. For this reason, the data do not extend below 10000 feet MSL. Future upgrades to the product will address the lower levels and other sources of turbulence including convection and mountain waves. The turbulence data are known as Graphical Turbulence Guidance (GTG), which was developed by the FAA and NCAR.
    The icing severity product combines a multitude of weather observations (temperature, humidity, satellite, observed surface weather and pilot reports, radar data, etc.) to diagnose areas of expected trace, light, moderate, and heavy icing. Separate overall icing probability and supercooled large drop (SLD) potential from 5 to 85% are provided as well. These products originate from the Current Icing Product developed by the FAA and NCAR.
    The next two weather products depict the latest radar data with each product updating approximately every 5 minutes. There are roughly 150 individual WSR-88D (NEXRAD) radars in the United States collecting data every 5 to 10 minutes. These are collected centrally and stitched together by various entities. Two radar depictions are provided because each source is currently considered experimental and each is derived from variations in the original source data. One is labeled base reflectivity and will often show ground clutter as well as weather features. This product primarily captures the radar echo nearest the surface. No attempt has been made to remove any non-weather features. The alternative product is the composite reflectivity that attempts to remove non weather features from the data. Both radar products show data with the best possible resolution of approximately 1 square kilometer grid boxes. Due to limitations of radar technology, blockage by mountains, and the spacing of radars, there are weather events when radar data does not detect or show a complete weather picture. The most commonly seen example is very shallow clouds with light precipitation like freezing drizzle or snow. An excellent web site with more information concerning radar technology and limitations is found at http://www.srh.noaa.gov/jetstream/remote/radarfaq.htm.
    Following the radar products are three satellite products, satellite visible, satellite infrared, and satellite water vapor. Visible refers to what typical cameras and the human eye would see. The infrared channel is especially useful at night and can be used together with temperature data to determine the height of the top of clouds. The water vapor channel indicates the moisture amounts in the upper atmosphere and does not directly show clouds. Regions that appear in the color scale stated as dry (orange/red colors) are very likely to be clear skies above FL180 whereas the green/blue/magenta colors are extremely likely to be cloud filled above FL180. In particular, the blue and green colors are very likely to indicate clouds above FL300. Intermediate values shown in gray shades could be either cloudy or clear above FL180. Even the driest zones shown in the darkest shade of red may have clouds below 10000 feet MSL.
    The next two items found in the weather product list are NCWD/F and NCWD/F Low Filter. This product is designed to locate any thunderstorms in the contiguous United States. It incorporates both radar and lightning data, which the latter significantly helps to locate thunderstorms in mountain regions where radar data are less reliable and also detects farther out to sea than the radars can sense. Similar to the radar products, it refreshes with new data approximately every 5 minutes (though not necessarily on the exact same schedule). Unlike radar products, convection shows both past data and an automated forecast of future thunderstorms. The forecasts for 30, 60, 90, and 120 minutes into the future are provided as probabilities. Though experimental, the National Convective Weather Forecast (NCWF) is based on proven scientific principles. The NCWD/F Low Filter product displays a subset of the convection where only those thunderstorms taller than 35,000 feet are found. For this reason, it may not show any thunderstorms at all during the cold season.
        The remaining trio of weather products, ceiling, visibility, and flight category originate from the National Ceiling and Visibility Analysis (NCV-A) product developed by the FAA and NCAR. The ceiling and visibility are used together to classify the flight category as Visual Flight Rules (VFR), marginal VFR (MVFR), Instrument Flight Rules (IFR), and low IFR. This set of rules is commonly used throughout the aviation industry. These three NCV-A products derive from all available observations including surface weather reports and satellite data and update approximately every 5 minutes. Due to limitations of the observations, the grid cells are approximately 5 kilometers apart at best. In data sparse regions, the best possible estimate of ceiling and visibility is assumed from the nearest surrounding data and may not represent the actual conditions at a specific point. Areas with a gray overlay indicate low confidence, whereas areas without correspond to normal confidence. Currently only an analysis product is available but scientists continue to develop a forecast version to predict future ceilings and visibility.

    Weather overlays in the Flight Path Tool include the primary relevant aviation weather products from the National Weather Service. At this time, the available overlays are METARs, TAFs, PIREPs, AIRMETs, and SIGMETs. These data are generally unscheduled in time so the application tries to refresh with the latest data every few minutes. All of the overlays have specific icons to represent the weather conditions and moving your screen pointer over any icon causes a text box to appear containing the original NWS text message. An example is shown in the figure below in the AIRMETs configuration section.
    The wind barb overlay is partly associated with the 3D grid of wind speed. Choosing the wind speed product will automatically activate the wind barb overlay revealing the direction of the wind. Placing the cursor over a wind barb will produce a pop-up text message of wind direction (degrees true not magnetic) and speed. A reference for how to interpret the wind barb presentation is found on the web at http://weather.aero/metars/description2.php. The density of the wind barbs matches the wind speed data but would be illegible on the screen if all points were shown simultaneously. Therefore, the software decides which wind barbs to plot automatically, but users may use the configure menu to control the density manually.
    Enabling specific gridded weather products will also activate corresponding AIRMETs and/or SIGMETs. For instance, choosing either icing product will automatically activate the icing AIRMETs and SIGMETs. Choosing flight category, ceiling, or visibility automatically activates the IFR and mountain obscuration AIRMETs; whereas choosing either radar or convection product automatically activates the display of convective SIGMETs. Once enabled, these overlays can be turned off manually using the Overlay menu, but they are programmed to return to this default behavior once you switch to one of the listed choices.

Effective use of zoom/pan and saving custom configurations

    The View menu contains options related to zooming and saving, deleting, and showing previously-created regions of interests. To zoom in, simply double-click with the left mouse button over the spot you wish to zoom into on the primary display panel. Consecutive zoom operations continue to zoom until the software can no longer display anything reasonable. To zoom out, you can single-click with the right mouse button. To keep the same zoom level but shift/pan the map in a specific direction, simply left-click and drag (while continuing to depress the mouse button) the map in the direction you desire. Letting go of the mouse button will stop the pan operation. An optional zoom/pan toolbar is available to use instead of the mouse. If you have the toolbar enabled, the mouse zoom/pan operations automatically become disabled and will not function until the toolbar is hidden again.
    The vertical cross-section viewing window can also be zoomed using the same mouse operations. Using this method, users can reveal more vertical detail but the horizontal axis will always remain the full flight path. In other words, the zooming is only done in the vertical (altitude) dimension.
    Once you create a plot showing a specific region you wish to save, use the View→Save View option and enter a name for the view in the Save a favorite view dialogue box. For consistent usage of the tool, the saved views are far quicker than using the various zoom/pan operations (mouse or toolbar) to focus directly on your area of interest. Besides saving the geographic location shown on the display, the various data layer choices are saved as well. Therefore, you could save a region showing one set of weather products, then switch weather products and save the same geographic region with different weather products under a different name. The View→Delete View option obviously removes a saved view from your list. The View→Default View option exists to jump-start the application (the next time it is launched) directly to your saved settings. View→Continental U.S. option is a quick way to zoom all the way out to the full ConUS if you wish to see more distant weather or decide to start from scratch to create a new zoom region. Finally, a map overview panel is provided for reference to get an idea of the surrounding area. The red box shown in the overview represents the region shown in the primary display panel and that red box can be moved or resized using the left mouse button but is not an effective means for performing a number of zoom/pan operations.

Obtaining a view along flight route

    Use the Tools menu and choose Flightpath, then pick either Click Way Points or Enter Station List. If you pick the first option, then click once with the left mouse button in the main display panel to start the path, then once again for each point along the desired route. When you reach the desired end of the flight path, double-click the left mouse button. Alternatively, right mouse click and pick Submit path. If you prefer to enter a list of abbreviations to describe a flight path, then pick the appropriate menu item. If so, a new dialogue box appears and you can enter a series of abbreviations to describe the route. At this time, you must enter four-letter ICAO abbreviations like "KDEN" not the three-letter airport identifiers. As an example you can enter the text string: KDEN, KSNY, KLBF, KOMA, KDSM, KORD.

Viewing a time-series of past, present, and future weather at a station (meteorogram)

    Use the Tools menu item and choose Meteorogram, then pick either Click Station or Enter Station. If you pick the first option, then click once with the left mouse button in the main display panel on a METAR or TAF reporting location (you must enable one or both overlay options in the Overlays menu). If you pick the second Meteorogram menu item, then a new dialogue box appears and you can enter a four-letter ICAO abbreviation like "KDFW."

Time controller and animation

    The time controller interface (see figure) allows users to alter the time of the gridded weather products. Overlayed data such as METARs, PIREPs, TAFs, AIRMETs, and SIGMETs are affected by changes to the selected time as well. The current time is indicated by the red vertical line and the corresponding UTC and local times are shown above the red line. The selected time of the gridded weather product is indicated by the orange square. The data displayed will be the nearest match in time to the selection and the actual valid time of the data can be found in the lower-right corner of the primary display panel. When in doubt of the valid time, be certain to look here for the actual valid time of the displayed product(s). Users may click (using the left mouse button) and drag (while depressing the same mouse button) this orange square backwards or forwards to select a time in the past or future.     The animation controls are relatively straight-forward. Click the play button to start animating and then click the same button to stop the animation. You can increase or decrease the speed of the loop as well as lengthen or shorten the amount of time spent on the final frame, referred to as “dwell.” Be aware that it takes the software some time to create the first loop of the animation so please be patient while all frames load; thereafter, the animation should run more quickly and smoothly. Maximum speed of the loop depends on many factors that the software developers cannot control like the speed of the computer and the load of the host computer due to various applications that are running on it.

Geographic Information System (GIS) map characteristics

    The Flight Path Tool application utilizes an ESRI ArcIMS® map service to provide the default map data to the application. At this time, most of the GIS data displayed has been pre-configured to show various data at specific resolutions and cannot be altered by users. A future version will allow users to configure these layers dynamically and add their own data (helicopter bases for example). At this time, the data available as users zoom into progressively smaller regions includes:

    The default ArcIMS® map server may fail for slow internet connections so a small subset of these data are built into the application. If the web map server fails, the application will automatically switch to using the less sophisticated built-in maps.

Configuring specific weather overlay options

    METARs are observations of surface weather including temperature, winds, moisture, visibility, ceiling, present weather obstructions (like rain/snow/fog), altimeter setting and more. These are NWS textual messages in their original form. The current application conveys some of the most important aviation information as an icon for sky coverage and flight category (VFR, MVFR, IFR, LIFR) whereas the other parameters are available for viewing by this configuration menu option (see figure). By default, when the screen cursor passes over a reporting site, a text message appears on screen to reveal that station's ceiling and visibility observation along with the full original text. Furthermore, to prevent excessive clutter on the screen, only a minimal set of data are displayed for all sites. As soon as the user requests other data (temperature for instance), the tool will reduce the number of stations shown to keep from completely obscuring other stations' data. Zoom in and out operations will result in a de-clutter technique that may remove some sites and/or reveal others. If the reporting site you seek is not shown, either zoom closer to that site or use this configuration dialogue box to enable more (or fewer) reporting sites.
    TAFs are terminal aerodrome forecasts and represent forecasts of surface weather conditions expected in the next 24 hours at specified airports. Not all sites that report METARs have TAFs issued. The TAF configuration dialogue box is not shown because there are no important configuration options for these data at this time. When the screen cursor appears over a TAF site, the full NWS text message should appear on the screen. This coded message is standard and not necessarily simple to decode by all users. We advise users to visit the ADDS web site to learn more about these data if needed (http://weather.aero/tafs/).

    PIREPs are pilot reports of weather, clouds, icing, turbulence, and other phenomenon that are received by various FAA services like radio communications between the cockpit and ground controllers. A small fraction of these reports arrive via automated reporting systems. Similar to METARs, these data are represented in this application by icons (see figure) for icing, turbulence, and cloud coverage. Placing the screen cursor over one of the icons produces the full text message as relayed by the NWS. Abbreviations found in these messages are standard practice and users are referred to the ADDS web site to learn more (http://weather.aero/pireps/). The altitudes displayed for PIREPs are above mean sea-level, not above ground level (unless specifically stated in the text, which is uncommon). Users can control the vertical altitude range of PIREPs that are displayed by using their mouse to drag either top and/or bottom orange rectangles in the configuration dialogue box's altitude slider bar. PIREPs either above the top or below the bottom of these orange rectangles are excluded from the display.

    AIRMETs are NWS advisories for possible adverse weather conditions including icing, turbulence, IFR, and mountain obscuration. SIGMETs are significant weather advisories for known or forecast hazardous icing, turbulence, or convection. Each type of advisory may be shown or hidden. As mentioned in the section about weather products, activating certain gridded weather products automatically enables their corresponding advisory product(s) by default. If these items are not desired, they must be manually hidden from the display after each switch of the gridded weather product. AIR/SIGMETs are generally issued every 6 hours unless amendments are needed and displayed in the tool within a few minutes of receipt by ADDS servers. As with other overlays, a small icon is placed at the center of this overlay product and when the screen cursor passes over this icon, the region covered by the AIR/SIGMET is highlighted graphically and the full NWS text message is shown on the screen. A new feature found in this version is the border (dashed line) of any AIRMET or SIGMET will also trigger the pop up text and area highlight, partially transparent. Depending on the zoom level of the application, it can be difficult to see the full extent of this overlay product so users are advised to zoom out if the highlighted polygon isn’t fully apparent.