XPLMNavigation API

The XPLM Navigation APIs give you some access to the navigation databases inside X-Plane. X-Plane stores all navigation information in RAM, so by using these APIs you can gain access to most information without having to go to disk or parse the files yourself.

You can also use this API to program the FMS. You must use the navigation APIs to find the nav-aids you want to program into the FMS, since the FMS is powered internally by X-Plane’s navigation database.

XPLMNavType

These enumerations define the different types of navaids. They are each defined with a separate bit so that they may be bit-wise added together to form sets of nav-aid types.

NOTE: xplm_Nav_LatLon is a specific lat-lon coordinate entered into the FMS. It will not exist in the database, and cannot be programmed into the FMS. Querying the FMS for navaids will return it. Use XPLMSetFMSEntryLatLon to set a lat/lon waypoint.

XPLMNavRef

typedef int XPLMNavRef;

XPLMNavRef is an iterator into the navigation database. The navigation database is essentially an array, but it is not necessarily densely populated. The only assumption you can safely make is that like-typed nav-aids are grouped together.

Use XPLMNavRef to refer to a nav-aid.

XPLM_NAV_NOT_FOUND is returned by functions that return an XPLMNavRef when the iterator must be invalid.

XPLMGetFirstNavAid

XPLM_API XPLMNavRef XPLMGetFirstNavAid(void);

This returns the very first navaid in the database. Use this to traverse the entire database. Returns XPLM_NAV_NOT_FOUND if the nav database is empty.

XPLMGetNextNavAid

XPLM_API XPLMNavRef XPLMGetNextNavAid(
                         XPLMNavRef           inNavAidRef);

Given a valid navaid ref, this routine returns the next navaid. It returns XPLM_NAV_NOT_FOUND if the navaid passed in was invalid or if the navaid passed in was the last one in the database. Use this routine to iterate across all like-typed navaids or the entire database.

XPLMFindFirstNavAidOfType

XPLM_API XPLMNavRef XPLMFindFirstNavAidOfType(
                         XPLMNavType          inType);

This routine returns the ref of the first navaid of the given type in the database or XPLM_NAV_NOT_FOUND if there are no navaids of that type in the database. You must pass exactly one navaid type to this routine.

XPLMFindLastNavAidOfType

XPLM_API XPLMNavRef XPLMFindLastNavAidOfType(
                         XPLMNavType          inType);

This routine returns the ref of the last navaid of the given type in the database or XPLM_NAV_NOT_FOUND if there are no navaids of that type in the database. You must pass exactly one navaid type to this routine.

XPLMFindNavAid

XPLM_API XPLMNavRef XPLMFindNavAid(
                         const char *         inNameFragment,    /* Can be NULL */
                         const char *         inIDFragment,    /* Can be NULL */
                         float *              inLat,    /* Can be NULL */
                         float *              inLon,    /* Can be NULL */
                         int *                inFrequency,    /* Can be NULL */
                         XPLMNavType          inType);

This routine provides a number of searching capabilities for the nav database. XPLMFindNavAid will search through every navaid whose type is within inType (multiple types may be added together) and return any navaids found based on the following rules:

  • If inLat and inLon are not NULL, the navaid nearest to that lat/lon will be returned, otherwise the last navaid found will be returned.

  • If inFrequency is not NULL, then any navaids considered must match this frequency. Note that this will screen out radio beacons that do not have frequency data published (like inner markers) but not fixes and airports.

  • If inNameFragment is not NULL, only navaids that contain the fragment in their name will be returned.

  • If inIDFragment is not NULL, only navaids that contain the fragment in their IDs will be returned.

This routine provides a simple way to do a number of useful searches: * Find the nearest navaid on this frequency. * Find the nearest airport. * Find the VOR whose ID is “BOS”. * Find the nearest airport whose name contains “Chicago”.

XPLMGetNavAidInfo

XPLM_API void       XPLMGetNavAidInfo(
                         XPLMNavRef           inRef,
                         XPLMNavType *        outType,    /* Can be NULL */
                         float *              outLatitude,    /* Can be NULL */
                         float *              outLongitude,    /* Can be NULL */
                         float *              outHeight,    /* Can be NULL */
                         int *                outFrequency,    /* Can be NULL */
                         float *              outHeading,    /* Can be NULL */
                         char *               outID,    /* Can be NULL */
                         char *               outName,    /* Can be NULL */
                         char *               outReg);    /* Can be NULL */

This routine returns information about a navaid. Any non-null field is filled out with information if it is available.

Frequencies are in the nav.dat convention as described in the X-Plane nav database FAQ: NDB frequencies are exact, all others are multiplied by 100.

The buffer for IDs should be at least 6 chars and the buffer for names should be at least 41 chars, but since these values are likely to go up, I recommend passing at least 32 chars for IDs and 256 chars for names when possible.

The outReg parameter tells if the navaid is within the local “region” of loaded DSFs. (This information may not be particularly useful to plugins.) The parameter is a single byte value 1 for true or 0 for false, not a C string.

FLIGHT MANAGEMENT COMPUTER

Note: the FMS works based on an array of entries. Indices into the array are zero-based. Each entry is a navaid plus an altitude. The FMS tracks the currently displayed entry and the entry that it is flying to.

The FMS must be programmed with contiguous entries, so clearing an entry at the end shortens the effective flight plan. There is a max of 100 waypoints in the flight plan.

XPLMCountFMSEntries

XPLM_API int        XPLMCountFMSEntries(void);

This routine returns the number of entries in the FMS.

XPLMGetDisplayedFMSEntry

XPLM_API int        XPLMGetDisplayedFMSEntry(void);

This routine returns the index of the entry the pilot is viewing.

XPLMGetDestinationFMSEntry

XPLM_API int        XPLMGetDestinationFMSEntry(void);

This routine returns the index of the entry the FMS is flying to.

XPLMSetDisplayedFMSEntry

XPLM_API void       XPLMSetDisplayedFMSEntry(
                         int                  inIndex);

This routine changes which entry the FMS is showing to the index specified.

XPLMSetDestinationFMSEntry

XPLM_API void       XPLMSetDestinationFMSEntry(
                         int                  inIndex);

This routine changes which entry the FMS is flying the aircraft toward. The track is from the n-1'th point to the n'th point.

XPLMGetFMSEntryInfo

XPLM_API void       XPLMGetFMSEntryInfo(
                         int                  inIndex,
                         XPLMNavType *        outType,    /* Can be NULL */
                         char *               outID,    /* Can be NULL */
                         XPLMNavRef *         outRef,    /* Can be NULL */
                         int *                outAltitude,    /* Can be NULL */
                         float *              outLat,    /* Can be NULL */
                         float *              outLon);    /* Can be NULL */

This routine returns information about a given FMS entry. If the entry is an airport or navaid, a reference to a nav entry can be returned allowing you to find additional information (such as a frequency, ILS heading, name, etc.). Note that this reference can be XPLM_NAV_NOT_FOUND until the information has been looked up asynchronously, so after flightplan changes, it might take up to a second for this field to become populated. The other information is available immediately. For a lat/lon entry, the lat/lon is returned by this routine but the navaid cannot be looked up (and the reference will be XPLM_NAV_NOT_FOUND). FMS name entry buffers should be at least 256 chars in length.

WARNING: Due to a bug in X-Plane prior to 11.31, the navaid reference will not be set to XPLM_NAV_NOT_FOUND while no data is available, and instead just remain the value of the variable that you passed the pointer to. Therefore, always initialize the variable to XPLM_NAV_NOT_FOUND before passing the pointer to this function.

XPLMSetFMSEntryInfo

XPLM_API void       XPLMSetFMSEntryInfo(
                         int                  inIndex,
                         XPLMNavRef           inRef,
                         int                  inAltitude);

This routine changes an entry in the FMS to have the destination navaid passed in and the altitude specified. Use this only for airports, fixes, and radio-beacon navaids. Currently of radio beacons, the FMS can only support VORs and NDBs. Use the routines below to clear or fly to a lat/lon.

XPLMSetFMSEntryLatLon

XPLM_API void       XPLMSetFMSEntryLatLon(
                         int                  inIndex,
                         float                inLat,
                         float                inLon,
                         int                  inAltitude);

This routine changes the entry in the FMS to a lat/lon entry with the given coordinates.

XPLMClearFMSEntry

XPLM_API void       XPLMClearFMSEntry(
                         int                  inIndex);

This routine clears the given entry, potentially shortening the flight plan.

XPLMNavFlightPlan

These enumerations defines the flightplan you are accesing using the FMSFlightPlan functions.
An airplane can have up to two navigation devices (GPS or FMS) and each device can have two flightplans.
A GPS has an enroute and an approach flightplan.
An FMS has an active and a temporary flightplan.
If you are trying to access a flightplan that doesn't exist in your aircraft, e.g. asking a GPS for a temp flightplan, FMSFlighPlan functions have no effect and will return no information.

XPLMCountFMSFlightPlanEntries

XPLM_API int        XPLMCountFMSFlightPlanEntries(
                         XPLMNavFlightPlan    inFlightPlan);

This routine returns the number of entries in the FMS.

XPLMGetDisplayedFMSFlightPlanEntry

XPLM_API int        XPLMGetDisplayedFMSFlightPlanEntry(
                         XPLMNavFlightPlan    inFlightPlan);

This routine returns the index of the entry the pilot is viewing.

XPLMGetDestinationFMSFlightPlanEntry

XPLM_API int        XPLMGetDestinationFMSFlightPlanEntry(
                         XPLMNavFlightPlan    inFlightPlan);

This routine returns the index of the entry the FMS is flying to.

XPLMSetDisplayedFMSFlightPlanEntry

XPLM_API void       XPLMSetDisplayedFMSFlightPlanEntry(
                         XPLMNavFlightPlan    inFlightPlan,
                         int                  inIndex);

This routine changes which entry the FMS is showing to the index specified.

XPLMSetDestinationFMSFlightPlanEntry

XPLM_API void       XPLMSetDestinationFMSFlightPlanEntry(
                         XPLMNavFlightPlan    inFlightPlan,
                         int                  inIndex);

This routine changes which entry the FMS is flying the aircraft toward. The track is from the n-1'th point to the n'th point.

XPLMSetDirectToFMSFlightPlanEntry

XPLM_API void       XPLMSetDirectToFMSFlightPlanEntry(
                         XPLMNavFlightPlan    inFlightPlan,
                         int                  inIndex);

This routine changes which entry the FMS is flying the aircraft toward. The track is from the current position of the aircraft directly to the n'th point, ignoring the point before it.

XPLMGetFMSFlightPlanEntryInfo

XPLM_API void       XPLMGetFMSFlightPlanEntryInfo(
                         XPLMNavFlightPlan    inFlightPlan,
                         int                  inIndex,
                         XPLMNavType *        outType,    /* Can be NULL */
                         char *               outID,    /* Can be NULL */
                         XPLMNavRef *         outRef,    /* Can be NULL */
                         int *                outAltitude,    /* Can be NULL */
                         float *              outLat,    /* Can be NULL */
                         float *              outLon);    /* Can be NULL */

This routine returns information about a given FMS entry. If the entry is an airport or navaid, a reference to a nav entry can be returned allowing you to find additional information (such as a frequency, ILS heading, name, etc.). Note that this reference can be XPLM_NAV_NOT_FOUND until the information has been looked up asynchronously, so after flightplan changes, it might take up to a second for this field to become populated. The other information is available immediately. For a lat/lon entry, the lat/lon is returned by this routine but the navaid cannot be looked up (and the reference will be XPLM_NAV_NOT_FOUND). FMS name entry buffers should be at least 256 chars in length.

WARNING: Due to a bug in X-Plane prior to 11.31, the navaid reference will not be set to XPLM_NAV_NOT_FOUND while no data is available, and instead just remain the value of the variable that you passed the pointer to. Therefore, always initialize the variable to XPLM_NAV_NOT_FOUND before passing the pointer to this function.

XPLMSetFMSFlightPlanEntryInfo

XPLM_API void       XPLMSetFMSFlightPlanEntryInfo(
                         XPLMNavFlightPlan    inFlightPlan,
                         int                  inIndex,
                         XPLMNavRef           inRef,
                         int                  inAltitude);

This routine changes an entry in the FMS to have the destination navaid passed in and the altitude specified. Use this only for airports, fixes, and radio-beacon navaids. Currently of radio beacons, the FMS can only support VORs, NDBs and TACANs. Use the routines below to clear or fly to a lat/lon.

XPLMSetFMSFlightPlanEntryLatLon

XPLM_API void       XPLMSetFMSFlightPlanEntryLatLon(
                         XPLMNavFlightPlan    inFlightPlan,
                         int                  inIndex,
                         float                inLat,
                         float                inLon,
                         int                  inAltitude);

This routine changes the entry in the FMS to a lat/lon entry with the given coordinates.

XPLMSetFMSFlightPlanEntryLatLonWithId

XPLM_API void       XPLMSetFMSFlightPlanEntryLatLonWithId(
                         XPLMNavFlightPlan    inFlightPlan,
                         int                  inIndex,
                         float                inLat,
                         float                inLon,
                         int                  inAltitude,
                         const char*          inId,
                         unsigned int         inIdLength);

This routine changes the entry in the FMS to a lat/lon entry with the given coordinates. You can specify the display ID of the waypoint.

XPLMClearFMSFlightPlanEntry

XPLM_API void       XPLMClearFMSFlightPlanEntry(
                         XPLMNavFlightPlan    inFlightPlan,
                         int                  inIndex);

This routine clears the given entry, potentially shortening the flight plan.

XPLMLoadFMSFlightPlan

XPLM_API void       XPLMLoadFMSFlightPlan(
                         int                  inDevice,
                         const char *         inBuffer,
                         unsigned int         inBufferLen);

Loads an X-Plane 11 and later formatted flightplan from the buffer into the FMS or GPS, including instrument procedures. Use device index 0 for the pilot-side and device index 1 for the co-pilot side unit.

XPLMSaveFMSFlightPlan

XPLM_API unsigned int XPLMSaveFMSFlightPlan(
                         int                  inDevice,
                         char *               inBuffer,
                         unsigned int         inBufferLen);

Saves an X-Plane 11 formatted flightplan from the FMS or GPS into a char buffer that you provide. Use device index 0 for the pilot-side and device index 1 for the co-pilot side unit. Provide the length of the buffer you allocated. X-Plane will write a null-terminated string if the full flight plan fits into the buffer. If your buffer is too small, X-Plane will write inBufferLen characters, and the resulting buffer is not null-terminated. The return value is the number of characters (including null terminator) that X-Plane needed to write the flightplan. If this number is larger than the buffer you provided, the flightplan in the buffer will be incomplete and the buffer not null-terminated.

GPS RECEIVER

These APIs let you read data from the GPS unit.

XPLMGetGPSDestinationType

XPLM_API XPLMNavType XPLMGetGPSDestinationType(void);

This routine returns the type of the currently selected GPS destination, one of fix, airport, VOR or NDB.

XPLMGetGPSDestination

XPLM_API XPLMNavRef XPLMGetGPSDestination(void);

This routine returns the current GPS destination.