| title | description | date |
|---|---|---|
Extended OpenAir file format specification |
SeeYou OpenAir specification with Naviter extensions, Copyright © 2024, Naviter d.o.o. All Rights Reserved |
2024-04-04 |
Version 1.0, Copyright © 2024, Naviter d.o.o. All Rights Reserved
The OpenAir format, widely utilized in gliding, paragliding, and hang gliding applications, serves to disseminate airspace information and visualize it on maps. Originally developed by WinPilot in 1998, this format has since been embraced and extended by Naviter. This document outlines the OpenAir format alongside the extensions introduced by Naviter.
General requirements:
- Encoding: UTF-8
- File Extension: Use
.openair, with.txtas legacy alternative - Structure: Text-based, with one command or data point per line
- Comment Syntax: Begins with
*and extends to the end of the line.
Geographic coordinates can be represented in two formats:
- Degrees, Minutes and Seconds (DMS) format:
DD:MM:SS[N|S]for latitude andDDD:MM:SS[E|W]for longitude. Example:108:26:46W - Degrees and Decimal Minutes (DDM) format:
DD:MM.mmm[N|S]for latitude andDDD:MM.mmm[E|W]for longitude. Example:45:15.531N
Use a consistant format for each command or data point, either DMS 45:40:30N 014:18:20E or DDM 45:40.500N 014:18.333E.
Altitude is specified in feet ft (recommended) or in meters m. Example: 300ft or 1500m.
Distance is measured in nautical miles nm and is implied, meaning it is specified without a unit. This applies to definitions such as radii, widths and segments, see: DA, DB, DY, or V for more.
An airspace definition consists of a series of commands grouped into a block starting with AC and the rest of the 'A' commands. This is followed by the geometric definiton of the airpsace, which utilizes commands starting with D and/or V
Important
Each individual airspace definition must begin with the AC command.
Commands beginning with A and define general attributes of an airspace.
Specifies airspace class exclusively. The use is refined from the original format, where it was used more broadly.
Format:
AC Class
Class Options:
| Class | Definition |
|---|---|
| A | Class A Airspace |
| B | Class B Airspace |
| C | Class C Airspace |
| D | Class D Airspace |
| E | Class E Airspace |
| F | Class F Airspace |
| G | Class G Airspace |
Example:
AC D
Defines the airspace's name.
Format:
AN Name
Here Name is the designated name for the airspace. For example CTR Muenchen. Any UTF-8 character is allowed, but to avoid issues with some older systems that might not display special characters correctly, it's better to use simpler versions (for example, change ü to ue).
Example:
AN ED-R6 Brokdorf H24
Optional. Identifies the type of airspace or a special-use airspace. Typically used immediately after the AC command.
Format:
AY Type
The Type field accepts various categories or functions of the airspace:
| Type | Description |
|---|---|
| AWY | Airway |
| CTR | Control Zone |
| GSEC | Glider Sector |
| MTMA | Militaty Terminal Manouvering Area |
| GP | Gllider Prohibited Area |
| P | Prohibited Area |
| Q | Danger Area |
| R | Restricted Area |
| RMZ | Radio Mandatory Zone |
| TRA | Temporary Reserved Area |
| TMZ | Transponder Mandatory Zone |
Example:
AC E
AY RMZ
Optional. Communication frequency of ATC station or authority overseeing the airspace - used by glider pilots for contanct.
Format:
AF Frequency
Example:
AC E
AY RMZ
AN RMZ ETMN-GLIDER HX
AF 123.300
Optional. Name of the controlling station for the specified airspace - a name that a glider pilot would use in a radio call.
Format:
AG Station Name
Example:
AC E
AY RMZ
AN RMZ ETMN-GLIDER HX
AF 123.300
AG Nordholz Radar
Defines the highest boundary (the ceiling) of the airspace, including the altitude's reference point.
Format:
AH Altitude AltRef
Altitude references must be AGL, FL, STD, AMSL . For an undefined upper limit, use UNL without specifying an altitude.
Example:
AH FL145
AL 1000ft MSL
Important
Each airspace must have only one upper altitude limit. Including multiple altitude references creates ambiguity and is considered invalid (e.g., 100m AGL/423m AMSL
Defines the lowest boundary (the floor) of the airspace, including the altitude's reference point.
Format:
AL Altitude AltRef
Altitude references must be AGL, FL, STD, MSL. For areas extending to the ground, use GND, omitting the altitude.
Example:
AH FL145
AL 1000ft AGL
Important
Each airspace must have only one lower altitude limit. Including multiple altitude references creates ambiguity and is considered invalid (e.g., 100m AGL/423m AMSL
| AltRef | Description |
|---|---|
| AGL | ft Above Ground Level |
| FL | Flight Level |
| STD | Standard Atmospheric Pressure |
| AMSL | Above Mean Sea Level |
| GND | Ground, no altitude. AL only, no numeric value |
| UNL | Unlimited, no altitude AH only, no numeric value |
Geometric definition commands, often used with variable assignemnt V, define airspace geometry. Points are specified in degrees, minutes, seconds (DMS) or degrees and decimal minutes (DDM) notation. Radii are defined in nautical miles nm , with unit omitted.
Polygons vertices are defined by a series of lines that start with DP. They are expected to be mapped clockwise and closed - last defined point is the same as the first . This is the recommended for outlining airspace geometry.
Format:
DP Point
Example:
DP 53:47:06 N 008:21:41 E
DP 53:50:58 N 008:55:25 E
DP 53:45:08 N 008:57:21 E
DP 53:41:10 N 008:23:38 E
DP 53:47:06 N 008:21:41 E
or
DP 53:47.100 N 008:21.700 E
DP 53:50.960 N 008:55.825 E
DP 53:45.800 N 008:57.211 E
DP 53:41.755 N 008:23.890 E
DP 53:47.100 N 008:21.700 E
Important
Do not mix DMS and DDM notations. Stick to one definition throughout the file.
Note
Combining airspace shapes defined with DA arcs with points defined as DP can result in inconsistencies in how airspace is displayed. Avoid using DA if possible.
Defines an arc between two bearings, with its center set by a V command before. The direction is clockwise by default, but can be altered with V.
Format:
DA Radius, Start Angle, End Angle
Example:
V X=39:13:00N 118:13:00W
DA 10, 270, 290
Note
The arc is over-defined with V and DB sentences. Calculate the center of the arc carefully to avoid inconsistent display across various implementations on client software.
Defines an arc between two points, with its center set by a V command before. The direction is clockwise by default, but can be altered with V.
Format:
DB Point 1, Point 2
Example:
V X=39:13:00N 118:13:00W
DB 39:36:40N 119:46:10W, 39:29:09N, 119:36:10W
Defines a circular area centered on a point set by a preceding V command. The radius is given in nautical miles.
Format:
DC Radius
Example:
AC Q
AN PARA Ailertchen EDGA
AH FL100
AL GND
V X=50:35:36 N 007:56:42 E
DC 2.00
Note
Although DY is part of the original WinPilot definition, we advise against using the DY type. It doesn't stitch well in a string of airways. Use DP instead to define airways more accurately.
This command sets up parameters for geometric definitions in DA, DB, DC, and DY commands, and must be declared beforehand.
Format:
V Command=Value
Comand and Value options:
| Command | Value | Description |
|---|---|---|
| D | + or - |
Sets the direction for DAand DBrecords. + is clockwise direction, which is also a default. |
| X | Point | Sets the center of the DA, DBand DC records. |
| W | Number | Sets the width of an airway in nm |
Example:
V X=39:29.9N 119:46.1W
DA 7,290,320
DA 10,270,290
DA 10,320,200
V D=-
DA 5,200,270