GeoJSON files used in enroute flight navigation - Akaflieg-Freiburg/enrouteServer GitHub Wiki

Enroute uses standard GeoJSON files to encode geographic maps containing aeronautical information. This text describes the files in more detail. A check for compliance is implemented in the class "Waypoint".

Map Information

The FeatureCollection of the GeoJSON file contains an additional optional entry, called "info". This is a semicolon-separated list of strings that describe the origin of the map data. Even if the entry exists, the string might be empty.

Features of the GeoJSON file

There are three properties contained in every feature of the GeoJSON file:

  • TYP - Describes the main type of the feature.

    • AD - Airfields

    • AS - Airspaces

    • NAV - NavAids

    • PRC - Procedures. This includes traffic circuits, holding patterns in control zones, are arrival/departure procedures for control zones

    • WP - Waypoints. This includes (mandatory) reporting points and generic user-defined waypoints.

    All features of the same TYP have the same geometry and the same list of optional and required properties. The TYPs are further subdivided into categories, as described below.

  • CAT - A string that describes the category of the feature, for instance as AD-GLD (=glider site) or CTR (=control zone). The possible values of CAT are described below for every value of TYP.

  • NAM - Name of the feature, as a human-readable string.

The types are described below in more detail.

TYP AD: Airfields

Airfields are GeoJSON features whose geometry is always a point. The airspace is described by the properties listed below.

Property: CAT - required

Type of the airfield. This is exactly one of the following strings.

  • AD - Civil or civil/military airfield or airport, without information about runways

  • AD-GRASS - Civil or civil/military airfield or airport, without a paved runway

  • AD-PAVED - Civil or civil/military airfield or airport, with paved runway

  • AD-INOP - Abandoned airfield

  • AD-GLD - Glider site

  • AD-MIL - Military airfield or airport, without information about runways

  • AD-MIL-GRASS - Military airfield, without a paved runway

  • AD-MIL-PAVED - Military airfield, with paved runway

  • AD-UL - Ultralight flying site

  • AD-WATER - Sea airfield

Property: COD - optional

ICAO code of the airfield. A typical entry reads "EDDE"

Property: COM - optional

Communication radio frequencies (e.g. ATIS). Frequencies are separated by newline characters. Entries should be sorted as follows:

  1. Tower frequencies

  2. Ground frequencies

  3. Apron frequencies

  4. Other

A typical entry reads "TWR 121.150 MHz\nGROUND 121.750 MHz\nAPRON 121.900 MHz"

Property: ELE - required

Elevation of the airfield as a number, in meters above the main sea level

Property: INF - optional

Information radio frequencies (e.g. ATIS). Frequencies are separated by newline characters. A typical entry reads "ATIS 133.450 MHz"

Property: NAM - required

Name of the airfield. A typical entry reads "ERFURT-WEIMAR"

Property: NAV - optional

Navigation frequencies of the airfield, such as ILS frequencies. Frequencies are separated by newline characters. A typical entry reads "ATIS 133.450 MHz"

Property: ORI - optional

Orientation of the most important runway, as a number between 0 and 360. Paved runways are always more important than unpaved runways. Among runways of the same type, longer runways are more important than unpaved ones.

Property: OTH - optional

Navigation frequencies of the airfield, such as frequencies that can be used to switch on the lights or frequencies for nearby airspaces. Frequencies are separated by newline characters.

Property: RWY - optional

Description of all operational runways. Runways are separated by newline characters. A typical entry reads "10/28, 2600x50m, ASPH, 095°"

Property: TYP - required

Always "AD"

Property: VAR - optional

Magnetic variation, as a number in the range 0-360°.

TYP AS: Airspaces

Airspaces are GeoJSON features whose the geometry is always a polygon. The airspace is described by the properties listed below.

Property: BOT - required

Lower boundary of the airspace, specified as a string in one of the following forms.

  • GND - Ground level

  • 5500 - 5500 ft above sea level

  • 1000 AGL - 1000 ft above ground level

  • FL 130 - flight level 130

Property: CAT - required

Category of the airspace. This is exactly one of the following strings.

  • A - Airspace class A

  • ATZ - Aerodrome Traffic Zone

  • B - Airspace class B

  • CTR - Control zone

  • C - Airspace class C

  • D - Airspace class D

  • DNG - Danger area, except parachute jumping exercise zones (for these, see PJE below)

  • E - Airspace class E

  • F - Airspace class F

  • FIR - Flight Information Region

  • FIS - Flight Information Service Sector

  • G - Airspace class G

  • GLD - Gliding Sectors

  • NRA - Nature reserve area

  • P - Prohibited area

  • PJE - Parachute jumping exercise zone

  • R - Restricted area

  • TIA - Terminal information area

  • TIZ - Terminal information zone

  • TMZ - Transponder mandatory zone

  • SUA - Special Use Airspace

Property: ID - required

Free-text string with the identifier of the item, as found in the openAIP database.

Property: NAM - required

Free-text string with the name of the airspace

Property: SBO - required

Number that describes the lower boundary of the airspace in feet, under the simplifying assumption that GND = 0 feet, and that we are operating in the ICAO standard atmosphere. This datum is used by Enroute Flight Navigation, to decide which airspace to show/hide if an airspace altitude limit is set by the user.

Property: TOP - required

The upper boundary of the airspace is specified as a string in the form described under "Property BOT".

Property: TYP - required

Constant string "AS".

TYP NAV: NavAids

NavAids are GeoJSON features whose geometry is always a point. The navaid is described by the properties listed below.

Property: CAT - required

One of the following strings describes the category of the navaid.

  • NDB

  • VOR

  • VOR-DME

  • VORTAC

  • DVOR

  • DVOR-DME

  • DVORTAC

Property: COD - required

The code name of the navaid, such as "KRH"

Property: ELE - optional

Elevation of the navaid, in meters over sea level.

Property: NAM - required

Full-text name of the navaid, such as "Karlsruhe"

Property: NAV - required

Radiofrequency of the navaid, as a string of the form "341.0 kHz", "113.60 MHz" or "113.60 MHz • 83X".

Property: MOR - required

Morse code of the station.

Property: TYP - required

Constant string "NAV"

Property: VAR - optional

Magnetic variation, as a number in the range 0-360°.

TYP PRC: Procedures

Procedures are GeoJSON features whose geometry is always a line. The airspace is described by the properties listed below.

Property: CAT - required

Constant string "PRC"

Property: GAC - optional

Guess if the procedure is meant for standard aircraft or Glider/UL/Helicopters. This is "blue" for standard aircraft and "red" for the others.

Property: NAM - optional

Name of the procedure, such as "TFC Glider"

Property: USE - required

One of the following strings describes the type of the procedure. This is one of the following strings

  • ARR - Arrival route

  • DEP - Departure route

  • HLD - Holding pattern

  • TFC - Traffic circuit

  • TRA - Transit route

Property: TYP - required

Constant string "PRC"

TYP WP: Waypoints

Waypoints are GeoJSON features whose geometry is always a point. The airspace is described by the properties listed below.

Property: CAT - required

One of the following strings describes the category of the waypoint.

  • MRP - Mandatory reporting point

  • NOTAM - Location of a NOTAM

  • RP - Reporting point

  • WP - Generic waypoint

Property: COD - required for CAT == MRP and CAT == RP

A code name of the waypoint, such as "EDDE-S1". The enroute app uses this property for the ID field on the waypoint description dialog.

Property: COM - optional

A string that describes an associated frequency, such as "EDDE - TWR 121.150 MHz".

Property: ELE - optional

Elevation of the waypoint, in meters over sea level.

Property: ICA - optional

A string with the ICAO code of an associated airfield, such as "EDDE".

Property: MID - optional

Internal ID of the waypoint in the AIXM database. This is a string such as "7295".

Property: NAM - required

Name of the waypoint, such as "ERFURT-WEIMAR (SIERRA1)". The enroute app uses this property for the title of the waypoint description dialog.

Property: NOT - optional

Notes attached to the waypoint.

Property: SCO - required for CAT == MRP and CAT == RP

Short description of the waypoint, such as "S1". The enroute app uses this property for the display name of the point on the moving map.

Property: TYP - required

Constant string "WP"

Property: VAR - optional

Magnetic variation, as a number in the range 0-360°.