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Dubbed BRANDS, it offers considerable data display flexibility; developers believe it should provide controllers more time for decision and enhance their ability to control and sequence air traffic...
THE ULTIMATE airspace system must be able to make air transportation more competitive with surface modes and still respond in a safe and efficient manner to the demands of the system user and the general public.
Over the past three decades, the air traffic control system within the United States has evolved to meet these challenges and the problems associated with expanding airport capacity with steadily increasing degrees of automation and new generations of air-terminal equipment.
To increase the quantity and quality of information presented to the air traffic controller in the terminal area, Target Corporation, in co-operation with the U.S. Government, has developed what we call BRANDS, an acronym for "Bright Radar Alpha Numeric Display System."
BRANDS combines primary and secondary radar information, alphanumerics and map data on a high contrast television-type display for viewing in daylight conditions. The equipment consists of three basic elements: a signal data processor, a data processing control and a video indicator, which can be combined in varying numbers as required by each particular system installation. BRANDS solid-state design incorporates all functions in one rack unit. Video indicator is a high brightness, high contrast, television display.
BRITE system developed earlier...
Since the early beginnings of air traffic control, the tower controller has always been responsible for handling arriving, departing and taxiing traffic in a timely and orderly manner. Originally, he had to rely entirely on his own eyes, aided by binoculars.
In the early 1970s, an electronic aid called the BRITE ("Bright Radar Indicator Tower Equipment") system was introduced to provide the tower controller with a display of the primary radar situation in the terminal area. Using a plan position indicator (PPI) and TV camera to provide a display that can be viewed in the tower without a hood, the radar video data is converted to TV format (see Figure 2).
The system displays only primary radar, with no capability to display aircraft identity and altitude data. Additionally, the television camera is unreliable, has poor stability and lacks control over the decay or persistence of the radar data.
Daily maintenance is required because of the non-solid-state analog nature of the circuitry and the low reliability of this type of hardware. While it is still more useful than a PPI, the BRITE display tends to wash out in the high ambient light conditions of an airport control tower.
Nevertheless, the BRITE system was adequate until traffic density increased to the point where tower controllers needed more information to make the vital decisions necessary for aircraft guidance.
... and later upgraded
The next step in upgrading the tower display was an evolutionary add-on approach. This approach is often dictated by economic considerations, although it frequently results in adding many new problems in solving the old ones.
To expand the capability of displaying beacon target symbols, identity and altitude data on the tower display, a second TV camera is added, together with an alphanumeric generator and display (Figure 3). The outputs of the two cameras are combined to generate the BRITE picture.
This expanded system provides the tower BRITE display with aircraft beacon position, identity and altitude data in alphanumeric format superimposed on the primary radar paints. But the other disadvantages of the BRITE system (low reliability, frequent maintenance and lack of a high-contrast display) are compounded with the addition of a second set of equipment. Also, it is difficult to obtain accurate registration between the primary radar target paint and its corresponding beacon target symbol.
The two TV cameras and two analog cathode ray tube (CRT) displays must be perfectly aligned; moreover, this alignment must be maintained to keep the required registration. Without perfect registration, the system creates ambiguities that the controller must resolve.
BRANDS improvements are numerous
We believe BRANDS solves these problems by providing a reliable, lowmaintenance system for the tower controller to have all the information required to make effective air traffic control decisions.
The conversion of input radar and beacon data into a television
format is made in completely solid-state digital equipment that
provides essentially perfect registration while requiring no adjustments
and eliminates use of a CRT display and TV camera. An integrated-
circuit digital memory is employed for high reliability.
All functions are performed in a 0.05 cubic metre box, replacing
two full racks of equipment in previous BRITE systems.
The newly developed BRANDS display, is a high-brightness, high-contrast television display. Based on CRT phosphor and optical filtering technology that we originally developed for cockpit displays, it delivers effective viewing in a brightly lighted control tower with no washout.
BRANDS displays the primary radar data combined with target symbols, identity codes and altitudes for all aircraft responding to beacon interrogations. In installations that have an existing map generator, a map is electronically overlaid with the other data and range rings are provided.
A standard SSR format is employed for beacon target symbols, identities and altitudes but other formats can be furnished. Microprocessor control makes it easy to customize the BRANDS for specific applications.
The controller has many options to modify the data through the flexibility of the control functions:
A low-altitude alerting feature (LAAS), customized for each site, provides a visual and audible warning when a Mode-C altitude report indicates that the aircraft is below the minimum altitude established for that location. Civil and military emergencies, communications failure and hijack warnings also are included.
Future applications varied
Because BRANDS is so versatile, its applications and expansion capabilities are virtually unlimited. For example, here are some additional BRANDS applications currently being studied:
The introduction of BRITE systems in the last decade was useful and helpful to the tower controller, but today he needs the greater capability of a system such as BRANDS to assist him in his task of safe and efficient control of high density air traffic.
A versatile control centre permits the controller to tailor the amount and type of displayed information to suit his needs. BRANDS allows the controller to spend a greater part of his time making decisions and controlling and sequencing traffic because he has a clear, unambiguous, dependable display of the traffic situation.
BRANDS is now being tested and evaluated in U.S. Government test facilities at Patuxent River, Maryland, and at Moffatt Field, California. So far, there has been enthusiastic acceptance by participating tower controllers.
