FlightLine APRT Overview | Airborne Position Reference Tool for ATC Towers

The following is an overview of the Flightline Airborne Position Reference Tool. You can either read this overview or watch the training video that have been developed by uAvionix designed to help you become proficient with the Flightline application.

Chapter 1. System Overview

uAvionix Flightline is a web-based ATC situational awareness application designed to improve airspace safety.

Flightline accomplishes this by leveraging ADS-B technology on both 1090 MHz and 978 MHz, displaying aircraft targets on an accurate and detailed airspace map. Flightline leverages uAvionix-owned and installed hardware to deliver reliable performance. This includes ADS-B receivers known as GBRs, strategically placed on and around the airport.

The tower equipment may belong to the Airport Authority or uAvionix. The system meets the requirements of the FAA's Airborne Position Reference Tool (APRT) system, as defined in the System Design Approval SDA and enables benefits outlined in the FAA's Situational Awareness Display System concept of operations. These benefits include enhancing safety for crucial operations such as:

• Nominal use cases,
• Wrong airport landings,
• Emergencies, and,
• Assisting in position determination for ADS-B equipped aircraft not in communication with the tower (NOR DOE)

Flightline also provides continuous system monitoring and status presentation to users. As you can see, the Flightline user interface provides clear orientation with key components like the detailed airspace map, ADS-B target icons with history trail and data tag, airport status and time, map navigation controls, and map layer controls.

Chapter 2. System State

The system status is consistently indicated in the upper right corner of your display, right under the aircraft identifier. There are three possible states:

1. Online. This is the nominal state, indicating that all systems are fully operational and delivering service as expected, with full redundancy.
2. Degraded. This indicates a system fault, such as a loss of redundancy, but the system is delivering acceptable service and remains operational for controller use.
3. Offline. This means the system is not meeting its performance metrics. When offline, you will notice a red border around your display. This means the system is not suitable for use by controllers.

To view the GBR status, left click on the system status indicator. This action will bring up the sensor status window, which lists critical GBR identifiers and their status indication. Green indicates online, while red indicates offline. Simultaneously, the map will show the GBR locations at their current GPS positions with corresponding status indications, green for online and red for offline.

When multiple GBRs are deployed, multiple zones may be created with redundant coverage from multiple GBRs.

User Preference Settings: Log In/Log Out

For operational displays, logging into Flightline is streamlined. The application utilizes a locally stored token, meaning no username or password is required for access.

The site URL is uniquely configured and supplied by uAvionix. The system is remotely monitored and automatically signs in following a restart. No other applications should be used on the PC and display for APRT, and ideally, the computer is configured in a kiosk mode.

For non-operational web licenses, a username, password, and a URL will be provided to access the site. To log out, click on the left exit icon found in the UI Basic Controls settings in the upper left. A dialog will then appear, and you should left click Log Out.

The “Contact uAvionix support” link is only present for non-operational displays.

Map Overview and Manipulation

Map navigation can be accomplished using your mouse or trackball via the on-screen map navigation controls or through touch on an iPad.

• Panning the map. If your setup is using a mouse or trackball, pan the map by holding the right button and dragging. If you are using an iPad, pan the map by dragging the screen in any area that does not contain a data tag.
  • NOTE: There is not a corresponding map navigation control to pan the map.
• Zooming the map. With a mouse or trackball, zoom using the scroll wheel. Using the on-screen controls, select the plus icon to zoom in or the minus icon to zoom out. On an iPad, zoom by pinching the screen with two fingers. The zoom buttons will also function.
  • NOTE: There is a maximum zoom level that is site-specific.
• Rotating the map. With a mouse or trackball, rotate the map by holding the right button while using the scroll wheel. Using the on-screen controls, rotate the map by dragging the compass arrow. Selecting the compass arrow returns the map to a north-up orientation. On an iPad, rotate the map by turning the screen with two fingers.
• Resetting the map. Locate the Home icon within the map navigation controls and left click or tap it. The map will reset based on the default zoom level and rotation.
• ADS-B target legend. To display the legend, click the legend icon or tap on iPad. Left click the X icon to hide it. The iconography mimics GPS performance and accuracy derived from the GPS quality indicators broadcast in the ADS-B message, as well as system latency and target speed.
• The legend includes icons for:
  • Close target, position accuracy is within the limits of the system requirements.
  • Open target, position accuracy may be outside the limits of the system requirements.

Secondary windows and manipulation, dynamic map insets

Dynamic map insets allow you to create and position up to five focus areas on the map. These focus areas can be used for visual reporting points, arrival or departure corridors, known hotspots or complex airspace intersections.

Each inset is individually configurable, including data tags, velocity vectors, zoom level and rotation. Insets remain on screen until they are removed by the user, even if the system is reset. To create an inset on a PC, hold down the shift key, then left click and drag the mouse to define the bounding box. The inset will appear outlined with a black border and orange handles.

To create an inset on an iPad, tap the map inset button, which disables normal touch controls. Then use the crosshair cursor to select the upper left and lower right corners of the focus area. Insets can be manipulated independently from the main map.

You can pan, zoom and rotate within an inset, just as you would the main display.

• To move an inset, hover over it, then click and drag it to the desired location.
• To resize an inset, hover over it and select the map layer settings icon to reveal the orange handles. Drag the handles to adjust the size, then select the icon again to set the new size. On an iPad, tap the inset to reveal the resize handles.
• To pan, hover over the inset and hold the right mouse or trackball button while dragging. On an iPad, simply drag the inset.
• To zoom, hover over the inset and use the scroll wheel. On an iPad, zoom by pinching with two fingers.
• To rotate, hover over the inset and hold the right mouse or trackball button while using the scroll wheel. On an iPad, rotate by turning the screen with two fingers.
• To configure or close an inset, hover over it to reveal the settings and close icons. Select the settings icon to open the map options dialog. Select the close icon to remove the inset.

Highlighting Areas Points of Interest: Map Layers

Flightline map layers are available by selecting the map layers icon. Available layers include water features and roads for visual reference. Airports can be displayed, including dedicated airport runways and nearby airports.

These maps are sourced from credible aviation sources such as Jeppesen Airport GIS or ForeFlight EFB data and are updated periodically. Range rings can be displayed at 1 nautical mile, 5 nautical miles, and 10 nautical miles from the airport reference point. VFR reporting points may also be displayed.

Runway extensions are available including extended centerlines with markers or gaps at every mile, and a 5-mile marker extending to 10 miles from the runway threshold. Temporary Flight Restrictions, or TFRS, are shown when active. Obstructions above 400 feet AGL are shown as orange dots when enabled.

NOTE: Hovering or tapping an obstruction will display additional details.

Optional custom map layers may be available depending on the airport. These can include local airspace markings, approach and departure paths, parajump areas, navigation beacons, and IFR fixes.

User-defined shared layers can be used for the temporary depiction of closures or restricted areas.

Changes to airport layouts follow normal ARAC cycles but are coordinated with the local facility before loading.

There are two types of map layers, local and shared.

• Local layers affect only the current display and are predefined by local air traffic management representatives.
• Shared layers synchronize across all displays for the airport.

NOTE: Primary display users can create, edit, and enable shared layers, while web license users can only view them.

To create or edit shared map layers, select the "Edit Shared Layers" icon. In the wizard, select "Add New Layer." In the "Add a New Layer" dialog, choose the layer type, polygon, circle, or flag, then click "Next."

Enter a name for the layer. Choose a style from the predefined options, or a color, and click Next. Now, draw the layer on the map. For a polygon, click to place each vertex, then double-click to finish the shape.

If you need more precision, you can add extra vertices by clicking the intermediate points. Select “Add Layer,” and then select "Publish Changes" to make the new layer viewable by other displays.

For a circle, click to set the center. Select “Add Layer,” then click the edge to set the size. For a flag, click where you want the flag placed. When you're done, click “Add Layer.” Your new layer will appear in the layer list.

If you see a cloud icon, that means the changes have not been published yet. If you want to refine it, click “Update.” When ready, click “Publish Changes” so the layer becomes viewable on other flightline displays and will synchronize when enabled or disabled. Click “X” to return to the display.

Data blocks and basic data tags

By default, each aircraft is displayed with a three-line basic data tag.

• Line 1: The first line shows the aircraft ID, or call sign, along with a vertical speed indicator.
• Line 2: The second line shows barometric altitude, based on the altitude correction setting, and ground speed in knots.
• Line 3: The third line shows the aircraft type, as defined by FAA standards, along with the mode AC squawk code.

Some sites may configure the system to display fewer than three lines by default.

To view additional aircraft information, select an aircraft using the mouse or trackball, or tap it on an iPad. This opens the expanded data tag, which displays information derived from the ADS-B message. Expanded data includes:

• The call sign, which identifies the aircraft or vehicle by call sign or tail number.
• The ICAO address, a unique 24-bit airframe identifier represented in hexadecimal format.
• Barometric altitude (Alt Baro) shown as uncorrected altitude.
• Corrected barometric altitude (Alt Corrected), which applies the local barometric pressure setting.
• Geometric altitude (Alt Geo), derived from GPS data.
• The squawk code, which represents the aircraft's mode A code.
• The emitter category, which identifies the aircraft. Rotorcraft, vehicle, or unmanned aircraft type, as defined by the ADS-B emitter category.
• Velocity, displayed as ground speed in knots.
• Vertical speed, displayed in feet per minute.
• The air or ground state (AG State), indicating whether the aircraft is airborne or on the ground.
• The ADS-B source, shown as 1090 ES for 1090 MHz ADS-B messages, or UAT for 978 MHz ADS-B messages.
• The navigation integrity category (NIC), which specifies the integrity containment radius around the reported position.
• Navigation accuracy for position (NACP), which specifies the accuracy of the target's reported position.
• Navigation accuracy for velocity (NACv), which specifies the accuracy of the reported aircraft velocity.
• Accuracy time to limit (Accuracy TTL), where values greater than 0 indicate the ADS-B message meets the 0.5 nautical mile accuracy requirement for APRT.
• Last update, which shows the number of seconds since the last ADS-B message was received.

Manual data tag movement and stars positioning

By default, data tags automatically offset to avoid overlapping. This automatic deconfliction can be disabled.

To manually move a data tag, hover over it until the tag highlights, then click and hold, drag the data tag to the desired position, and release. On an iPad, press and hold until data tag until it highlights, then drag it.

Flightline also supports stars number keypad conventions for precise data tag placement. Using the number keypad followed by enter positions the data tag around the aircraft symbol relative to clock positions. Pressing 5 resets manual offsets and holding the period key forces automatic deconfliction.

Advanced user interface controls and target settings

Advanced user interface settings are accessed by selecting the gear icon in the basic configuration settings panel. This menu can be moved by clicking and dragging its title bar.

• The altitude ceiling setting allows you to define an upper altitude limit for aircraft displayed on the map. By default, this filter is based on corrected altitude. To override it, select the flight level MSL option and enter the desired ceiling.
• Altitude correction settings control how barometric altitude is displayed. Options include standard pressure set to 29.92 inches of mercury or current METAR data. When using current METAR, Flightline pulls the local METAR hourly.
• System time can be displayed as either UTC or local time by selecting the show time as local option.
• Data tag settings allow customization of what information appears in the data tag. You can enable or disable the aircraft ID, altitude and velocity, or aircraft type.
• Text size can also be adjusted for readability based on zoom level.
• Target settings allow further control of how aircraft are displayed.
• Position trail breadcrumbs can be enabled to show recent ADS-B positions.
• The number of breadcrumbs displayed can be adjusted.
• Velocity vectors can be enabled to show the projected aircraft position based on heading and speed. You can select the number of seconds the vector extends ahead of the aircraft.
• Aircraft and vehicle icon size can be adjusted using the plus and minus controls.

Resource material. User manual and quick reference guide.

For comprehensive information on the Flightline APRT system, refer to the Flightline user manual. The user manual provides detailed explanations of system functionality, configuration options, and operational behavior. For quick reference during operations, the Flightline quick reference guide is also available.

This guide summarizes key features including map navigation, data tag manipulation, and advanced user interface controls. Together, these resources are designed to support both initial familiarization and ongoing operational use of the Flightline system.

Vendor contact information for reporting system issues

uAvionix provides a three-tiered support team to assist with reporting and resolving system issues. Support tiers:

• Tier 1 support is outsourced to a US-based call center and provides after-hours phone coverage. This level focuses on collecting customer information, documenting the issue, creating an accurate trouble ticket, and escalating when necessary.
• Tier 2 support provides technical assistance for equipment installation, system configuration, troubleshooting, and escalation.
• Tier 3 support consists of engineers equipped to perform root cause analysis, support catastrophic failures, handle non-typical installations, and develop corrective solutions.

Each inbound support contact, whether by phone, email, or web submission, results in the creation of a trouble ticket. All tickets are logged and tracked through resolution. Support is available through the following methods.

By phone, using the toll-free number 844-827-2372. For the FAA APRT direct help desk, use extension 7600.

For web-based support, visit the uAvionix support contact page to submit a self-service Support Ticket.

Thank you for completing the Flightline Airborne Position Reference Tool user familiarization video.

We hope this overview/training has provided a clear understanding of the system's capabilities and operation. For additional questions or support, please contact uAvionix support.