Appendix G - Sector File Formatting Requirements
This page documents the formatting requirements for .sct and .sct2 sector files. The rules specified here apply specifically to VRC. Other radar client programs may be more or less strict than VRC in terms of formatting.
VRC supports two formats, known as the .sct and .sct2 formats. The .sct format existed prior to the development of VRC and is supported by other radar clients such as ASRC and ProController. The .sct2 format was introduced with VRC 1.1 and adds two new sections to the file, namely the [REGIONS] and [LABELS] sections, which are described below.
Note that if you use the new [REGIONS] and [LABELS] sections in a .sct file, VRC will reject the file with a syntax error. ASRC will most likely still load the file, but you will often get undesired results. This is because ASRC will ignore the [REGIONS] and [LABELS] section headers and treat the region and label entries as though they were a continuation of the previous section, whatever it may be. This is why you should never use [REGIONS] and [LABELS] sections in a .sct file. Use them only in .sct2 files.
Comments are lines which are ignored by the radar client and are only meant to be a note or reminder for sector file authors and maintainers. To place a comment in a sector file, precede the comment text with a semicolon. For example, the first line of the following sector file excerpt is a comment indicating that the following lines comprise the Runway 4R/22L centerline:
Comments can also appear at the end of a line after actual data, like so:
Blank lines are ignored by the sector file parser, so they are acceptable.
Every section uses latitude and longitude coordinate formatting. To specify a coordinate, you provide both the latitude and longitude for the point, using degrees, minutes, seconds, and decimal seconds. These values are separated by a decimal point. Latitudes must be prefixed with an N or an S, for latitudes north or south of the equator, respectively. Longitudes must be prefixed with a W or an E, for longitudes west or east of the prime meridian (zero degrees longitude,) respectively. Examples of this formatting can be found throughout this document.
Note that for some sections, a coordinate can also be specified by using a navaid identifer, such as the identifier for a VOR, NDB, FIX (intersection) or airport. In that case, the latitude and longitude for the specified navaid will be used to draw the given item. This is handy for drawing airways or procedures that use navaids as waypoints on the procedure. An example of this formatting is shown in the [LOW AIRWAY] section description below.
Sector file colors are defined by a number representing the red, green and blue components of a color. This number is a 24 bit integer where the leftmost 8 bits are the blue color, the middle 8 bits are the green color, and the rightmost 8 bits are the red color.
To convert from individual 8-bit red, green and blue values (in the range 0-255) into the 24 bit integer format, use the following formula:
(BLUE x 65536) + (GREEN x 256) + RED
The sector file format provides the ability to define named color macros for use throughout the file. This allows you to assign the same named color to a collection of line segments and be able to change their color by just changing the numeric value of the color definition, instead of having to update the color value for each line segment individually. Named color definitions can be used anywhere a color value can be used. Color definitions must appear at the top of the sector file before any section header. Each color definition must appear on a separate line. Each one must consist of the keyword "#define", followed by the color name, followed by the numeric value. Examples:
The [INFO] Section
Every sector file must have an [INFO] section. This section defines some basic required parameters about the airspace represented by the sector file. Here's an example:
The first line defines the name of the sector file. In VRC, this is shown in the controller data at the bottom of the controller list when you click on a controller.
The second and third lines are the default callsign and the default airport for the sector. These are ignored by VRC.
The fourth and fifth lines are the latitude and longitude of the default sector center point. This is where your scope will be centered when first opening the sector file.
The sixth and seventh lines represent the number of nautical miles per degree of latitude and longitude, respectively. The first of these two should normally be 60, since lines of latitude are always parallel. The second value will decrease the further the sector is from the equator, because lines of longitude converge as you move towards the poles. These two values are used to "squeeze" the sector data display so that it appears normal on the scope.
The eighth line is the magnetic variation for the sector. This is used to rotate the display on the scope so that runways and aircraft ground tracks are aligned relative to magnetic north.
The ninth line is a sector scale value, which is ignored by VRC.
The [VOR] Section
This section defines all the VORs in the airspace. Each VOR must be on a separate line. Each line must contain the VOR identifier, followed by the VOR frequency, followed by the latitude, followed by the longitude. These four values must be separated by at least one space. Example:
The [NDB] Section
This section defines all the NDBs in the airspace. The formatting is identical to the [VOR] section.
The [AIRPORT] Section
This section defines all the Airports in the airspace. Each airport must be on a separate line. Each line must contain the airport identifier, followed by the tower frequency, followed by the latitude, followed by the longitude, and finally the class of airspace in which the airport lies. These five values must be separated by at least one space. Example:
The [RUNWAY] Section
This section defines all the runways for all airports in the airspace. Each runway definition must be on a separate line. A runway definition is comprised of the following eight space-separated fields:
Here's an example showing the runways for three different airports. The comments indicating the airport code are not required:
The [FIXES] Section
The fixes section defines all the named VOR radial intersections or GPS waypoints in the airspace. Each fix definition must be on a separate line. Each line must contain the fix name, followed by the latitude of the fix, followed by the longitude. These fields must be separated by at least one space. Example:
The [ARTCC] Section
This section is used to define major ARTCC/FIR boundaries. Each line defines a single line segment. The line must consist of the name of the boundary that this segment is part of, followed by the latitude and longtitude of the start and end points of the line segment. These five fields must be separated by at least one space. The name is not actually used by VRC, but it must be included for backwards compatibility with older radar clients. The name cannot contain any spaces. Example:
The [ARTCC HIGH] Section
This section is identical to the [ARTCC] section. It is typically used to define high-altitude ARTCC sector boundaries. It exists as a separate section so that it can be toggled on/off separately by the user.
The [ARTCC LOW] Section
This section is identical to the [ARTCC] section. It is typically used to define low-altitude ARTCC or TRACON sector boundaries. It exists as a separate section so that it can be toggled on/off separately by the user.
The [SID] and [STAR] Sections
These sections are used to define SID (Standard Instrument Departure) and STAR (Standard Terminal Arrival Route) diagrams, which can be toggled on/off individually by the user as needed. They are also commonly used to define IAPs (Instrument Approach Procedures) as well as vectoring diagrams, sector video maps, and even complex airport diagrams. In VRC, the items defined in these sections are collectively referred to as "Diagrams" and each one can be toggled on/off via the Diagrams Window. The Diagrams Window contains two lists, one for the diagrams defined in the [SID] section, and one for the diagrams defined in the [STAR] section. It doesn't matter what type of diagrams you place in each section.
These sections are somewhat unique in that the formatting requirements incorporate both a fixed-width field and space-delimited fields. An individual diagram consists of one or more lines in the sector file. Each line defines a single line segment in the diagram. The first line of the diagram definition contains the name of the diagram. The name field must be exactly 26 characters in length. If the name of the diagram is shorter than 26 characters, trailing spaces must be added to fill the 26 characters. After the first 26 characters, there can be one or more optional spaces, followed by the latitude and longitude of the start and end points of the line segment, followed by an optional color name or value. If no color name or value is given, the diagram will be drawn using the default SID or STAR color as defined in the radar client settings.
Subsequent lines in a diagram definition must have 26 spaces, followed by the latitude and longitude for the start and end points of the current line segment, followed by an optional color name or value. In other words, subsequent segment definitions are identical to the starting segment definition, except that only the starting segment contains the name of the diagram in the first 26 characters. VRC will continue reading lines and adding them to the current diagram definition until it encounters the start of a new diagram (signified by a name present in the first 26 characters) or the start of a new section.
In the following example, two diagrams are defined. One is the Gardner Three (GDM3) arrival into KBOS, and the other is the Woons One arrival into KBOS. These examples illustrate how navaid names can be used in place of latitude and longitude values.
The [LOW AIRWAY] and [HIGH AIRWAY] Sections
These sections are used to define low altitude and high altitude airways. The formatting is identical to the [ARTCC] section. The name of the airway segment is drawn on the scope at the center point of the segment, when the associated airway is toggled on by the user. Navaid names can be used in place of latitude and longitude values. Example:
The [GEO] Section
This section is used to define colored line segments for any purpose. It is typically used to define geographic data such as coastlines or major bodies of water, or for other static items such as special use airspace, airport diagrams, etc. Each line in this section defines a single line segment. The line must contain the latitude and longitude of the start and end points of the segment, followed by a color name or value. Example:
The [REGIONS] Section
This section is only valid in .sct2 files. For the formatting requirements and examples of the [REGIONS] section, refer to Appendix F.
The [LABELS] Section
This section is only valid in .sct2 files. For the formatting requirements and examples of the [LABELS] section, refer to Appendix F.
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