Accessing LiveTraffic's Aircraft Data

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Ways for plugin developers to access information of LiveTraffic's aircraft
There are a few ways to access LiveTraffic's aircraft data programmatically:
Read Traffic Data
LTAPI
LiveTraffic offers a C++ API to read (nearly) all information of all aircraft that LiveTraffic operates. With a single call, you are provided with a vector of LTAircraft objects. You can subclass the LTAircraft class to add your own management functionality. Technically, data is packed and transferred very efficiently in the background and transferred by means of binary dataRefs. Available from X-Plane.org and from GitHub. Includes a sample plugin implementation demonstrating most features.
I am aware of one plugin, which makes already active use of it, which is ABC.
TCAS Targets
As of X-Plane 11.50, X-Plane offers a new approach called TCAS Override to report planes to TCAS systems and to other plugins interested in multiplayer aircraft informaton. New plugins shall definitely follow this new approach. Find implementaton details in Laminar's blog entry.
While LiveTraffic has TCAS control, and only then, LiveTraffic reports the closest up to 63 aircraft as TCAS targets with the following values:
.../tcas/targets/
LiveTraffic's Value
modeS_id
24 bit Mode S transponder code
modeC_code
Squawk Code
flight_id
Flight number or, if unavailable, tail number (registration)
icao_type
ICAO aircraft type designator
All dataRefs under sim/cockpit2/tcas/targets/position are filled as expected and documented except for the following, which are not populated:
weight_on_wheels
wing_sweep
yolk_pitch/roll/yaw [sic!]
Standard Multiplayer DataRefs
The classic 19 sets of multiplayer dataRefs (sim/multiplayer/position/plane*) are mirrored automatically while providing TCAS target information. So the closest 19 aircraft are also available via this channel while LiveTraffic has TCAS control.
With TCAS Override, XPLMCountAircraft returns the actual number of reported aircraft independend of how many AI Aircraft the user has configured. So you can rely on this number and don't necessarily need to always monitor all these 19 slots. Still, for backward compatibility, LiveTraffic fills unused slots' _x/y/z values with > 9999999. (They are deliberately not set to 0 in this case, because 0/0/0 is a totally valid geographic location.)
Starting with 11.50 Beta 8, X-Plane can return values larger than 20 in XPLMCountAircraft! If you are dealing with the 19 multiplayer slots only you need to make sure to handle larger values correctly, e.g. by capping at 20.
Shared DataRefs for Textual Information
As a supplement to the standard multiplay dataRefs, textual aircraft and flight information is provided via shared dataRefs of type xplmType_Data as suggested by FSTramp (LiveTraffic issue #144) with # being a plane number between 1 and 63:
sim/multiplayer/position/plane#_tailnum - Tail number, registration
sim/multiplayer/position/plane#_ICAO - ICAO Aircraft type
sim/multiplayer/position/plane#_manufacturer - Aircraft manufacturer, human readable
sim/multiplayer/position/plane#_model - Aircraft model, human readable
sim/multiplayer/position/plane#_ICAOairline - ICAO airline/operator code
sim/multiplayer/position/plane#_airline - Airline/operator
sim/multiplayer/position/plane#_flightnum - Flight number
sim/multiplayer/position/plane#_apt_from - Origin airport
sim/multiplayer/position/plane#_apt_to - Destination airport
sim/multiplayer/position/plane#_cslModel - CSL model used to render the plane (folder name plus model id)
A plugin wanting to use this data must call XPLMShareData, can optionally thereby register a notification callback, then calls XPLMFindDataRef and XPLMGetDatab as usual. Provide at least a 40 character buffer per dataRef to be on the safe side.
Take Over Camera View of an Aircraft
A LiveTraffic user can activate a camera view on any aircraft. LiveTraffic publishes which aircraft the camera shows and even provides a setting that disables LiveTraffic's internal camera implementation so that a 3rd party camera tool can instead provide the view.
LiveTraffic operates two integer shared dataRefs with global names, ie. not LiveTraffic-specific. In fact, they pick up the naming scheme as used by the shared dataRefs for textual aircraft information. Shared dataRefs have the advantage that a reading plugin can register a notification callback and several plugins can write to them and this way inform both the camera plugin as well as LiveTraffic. See SDK documentation on XPLMShareData.
sim/multiplayer/camera/tcas_idx is set to the TCAS index (1..63) of the aircraft being viewed, or to -1 if that aircraft has no TCAS index, or to 0 if camera view is turned off.
sim/multiplayer/camera/modeS_id is set to the aircraft key, usually the 24bit ICAO transponder code (like 0xAB1234=11211316) of the aircraft being viewed, or to 0 if camera view is turned off.
A camera plugin
should register a notification on sim/multiplayer/camera/tcas_idx because this dataRef is set last. By the time your notification callback triggers both modeS_id and tcas_idx will be updated.
should, in the notification callback, read one or both values and do your camera magic if values are not 0.
can - optionally but welcome - write the dataRef values, too, ie. if your user switches off the camera view then update modeS_id and tcas_idx (in this order) to 0 to indicate that no camera view is on an aircraft; or even update them with aircraft info if your user selects another aircraft inside your plugin. (Note that your callbacks get called even if you set the values...weird twist of the SDK implementation.)
Alternatively, a camera plugin can just use LTAPI, which handles all that internally:
Override LTAPIAircraft::toggleCamera(), which is called whenever the shared dataRef values change on the current aircraft and even provides you with a pointer to the previous aircraft if any. The LTAPIExample plugin includes an example implementation.
LTAPIAircraft::setCameraAc() and LTAPIConnect::clearCameraInfo() are available for write operations.
UDP Broadcast in ForeFlight Data Format
You can make use of the data broadcasted on the ForeFlight channel for other purposes than just ForeFlight. The ForeFlight data format is described here and LiveTraffic sticks to it. Example broadcasts (around OMDB) look like this:
Example ForeFlight broadcast datagrams
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XGPSLiveTraffic,55.367,25.256,240.6,119.235,52.2
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XATTLiveTraffic,119.3,1.8,-0.5
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XTRAFFICLiveTraffic,4921470,25.269,55.200,5023.0,0.0,1,289.6,208.9,SWR243
4
XTRAFFICLiveTraffic,7701531,25.252,55.359,9.9,0.0,0,123.0,14.9,CEB015
5
XTRAFFICLiveTraffic,8994918,25.157,55.366,6707.5,2711.5,1,273.7,266.6,GFA513
6
XTRAFFICLiveTraffic,9003216,25.245,55.366,36.9,0.0,0,253.2,11.2,UAE529
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User plane's position is broadcasted with 1Hz, its attitude with 5Hz. The repeat interval of traffic data is not defined by ForeFlight and configurable in LiveTraffic.
Output port is 49002 as defined by ForeFlight. There is no GUI setting for it so that nobody can accidently change it. But you'll find it in LiveTraffic's configuration file.
Here's a simplistic Python script, with which I test receiving any broadcasts. It does not interpret the data, but only displays it together with a timestamp. It works for Python 2 and 3 (only the output format slightly differs) and takes just one parameter, the port number:
udp_listen.py
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#!/usr/bin/python
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​
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import sys
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import socket
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import time
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​
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#---socket creation
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connexion = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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connexion.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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if sys.platform != "win32":
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	connexion.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)
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​
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#---Bind
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try:
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    connexion.bind(('', int(sys.argv[1])))
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except socket.error:
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    print ("connexion failed")
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    connexion.close()
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    sys.exit()
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​
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#---wait for and print data
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while 1:
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    data, addr = connexion.recvfrom(1024)
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    print (time.time(), ":", data)
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​
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Called like ./udp_listen.py 49002, it would output received UDP datagrams continuously like this:
Example Output of udp_listen.py
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(1554490061.876467, ':', 'XTRAFFICLiveTraffic,3958292,50.021,8.430,1569.0,-1146.4,1,69.6,186.4,DLH805')
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(1554490061.876575, ':', 'XTRAFFICLiveTraffic,3958350,50.035,8.545,324.9,0.0,0,58.1,2.3,DLH2VH')
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(1554490061.876621, ':', 'XTRAFFICLiveTraffic,3958370,50.043,8.522,350.3,0.0,0,70.4,59.8,DLH8A')
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(1554490061.878866, ':', 'XTRAFFICLiveTraffic,3958394,50.048,8.570,366.6,0.0,0,0.0,0.0,DLH5MR')
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(1554490061.889803, ':', 'XGPSLiveTraffic,8.583,50.032,106.5,180.000,0.0')
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(1554490061.891284, ':', 'XTRAFFICLiveTraffic,3957833,50.042,8.582,358.0,0.0,0,27.2,12.4,DLH21U')
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(1554490061.900316, ':', 'XTRAFFICLiveTraffic,3958441,50.044,8.536,341.7,0.0,0,81.9,30.8,DLH1449')
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(1554490061.923233, ':', 'XTRAFFICLiveTraffic,3958443,50.045,8.569,360.9,0.0,0,270.0,0.0,DLH57F')
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(1554490061.944078, ':', 'XTRAFFICLiveTraffic,3958499,50.043,8.561,351.1,0.0,0,162.2,11.5,DLH044')
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(1554490061.95145, ':', 'XATTLiveTraffic,114.3,-1.3,0.2')
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(1554490061.964778, ':', 'XTRAFFICLiveTraffic,3958610,50.072,8.526,23984.0,135.9,1,335.5,332.7,EWG1910')
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(1554490061.987202, ':', 'XTRAFFICLiveTraffic,3958617,50.040,8.575,347.0,0.0,0,60.1,24.4,DLH9KL')
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(1554490061.992343, ':', 'XTRAFFICLiveTraffic,3958157,50.043,8.547,342.5,0.0,0,145.1,22.6,DLH087')
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(1554490062.009156, ':', 'XTRAFFICLiveTraffic,3960929,50.041,8.562,345.9,0.0,0,248.7,9.7,GEC8343')
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(1554490062.029472, ':', 'XTRAFFICLiveTraffic,4458944,50.039,8.555,339.9,0.0,0,247.5,20.5,EJU25DA')
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(1554490062.05433, ':', 'XTRAFFICLiveTraffic,4566062,50.049,8.589,359.1,0.0,0,342.2,4.1,SAS1636')
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(1554490062.076019, ':', 'XTRAFFICLiveTraffic,4920849,50.029,8.542,452.8,-1150.5,1,69.9,125.7,SWR1076')
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(1554490062.094481, ':', 'XATTLiveTraffic,114.3,-1.3,0.2')
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(1554490062.098079, ':', 'XTRAFFICLiveTraffic,4921315,50.041,8.559,343.6,0.0,0,0.0,0.0,SWR106U')
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(1554490062.121316, ':', 'XTRAFFICLiveTraffic,5270561,50.032,8.526,324.9,0.0,0,190.1,20.1,ADR125')
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(1554490062.145733, ':', 'XTRAFFICLiveTraffic,7786223,49.952,8.592,8000.0,0.0,1,249.1,280.6,SIA326')
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(1554490062.152416, ':', 'XATTLiveTraffic,114.3,-1.3,0.2')
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(1554490062.167006, ':', 'XTRAFFICLiveTraffic,7867067,50.060,8.653,2733.6,682.0,1,71.9,228.2,CPA282')
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(1554490062.197146, ':', 'XTRAFFICLiveTraffic,3958217,50.049,8.570,368.4,0.0,0,0.0,0.0,DLH892')
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(1554490062.299546, ':', 'XTRAFFICLiveTraffic,3958350,50.035,8.545,324.9,0.0,0,58.1,2.3,DLH2VH')
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(1554490062.354267, ':', 'XATTLiveTraffic,114.3,-1.3,0.2')
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(1554490062.403429, ':', 'XTRAFFICLiveTraffic,3958441,50.044,8.536,341.7,0.0,0,81.9,30.8,DLH1449')
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(1554490062.504334, ':', 'XTRAFFICLiveTraffic,3958443,50.045,8.569,360.9,0.0,0,270.0,0.0,DLH57F')
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(1554490062.55615, ':', 'XATTLiveTraffic,114.3,-1.3,0.2')
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(1554490062.608154, ':', 'XTRAFFICLiveTraffic,3958610,50.072,8.526,23984.0,135.9,1,335.5,332.7,EWG1910')
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(1554490062.693573, ':', 'XGPSLiveTraffic,8.583,50.032,106.5,180.000,0.0')
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(1554490062.710873, ':', 'XTRAFFICLiveTraffic,3960929,50.041,8.562,345.9,0.0,0,248.7,9.7,GEC8343')
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(1554490062.757548, ':', 'XATTLiveTraffic,114.3,-1.3,0.2')
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(1554490062.915558, ':', 'XTRAFFICLiveTraffic,4921315,50.041,8.559,343.6,0.0,0,0.0,0.0,SWR106U')
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(1554490062.96226, ':', 'XATTLiveTraffic,114.3,-1.3,0.2')
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(1554490063.018004, ':', 'XTRAFFICLiveTraffic,7786223,49.952,8.592,8000.0,0.0,1,249.1,280.6,SIA326')
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(1554490063.120083, ':', 'XTRAFFICLiveTraffic,7867067,50.060,8.653,2733.6,682.0,1,71.9,228.2,CPA282')
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(1554490063.162793, ':', 'XATTLiveTraffic,114.3,-1.3,0.2')
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(1554490063.220842, ':', 'XATTLiveTraffic,114.3,-1.3,0.2')
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(1554490063.364389, ':', 'XATTLiveTraffic,114.3,-1.3,0.2')
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(1554490063.564868, ':', 'XATTLiveTraffic,114.3,-1.3,0.2')
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Export Traffic Data
See the Advanced Options to export traffic data to a *.csv file in a format very similar to what is discussed above. These export files can even be used to re-feed them into LiveTraffic.
TCAS
Feeding Data to LiveTraffic
Last modified 8mo ago
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Contents
Read Traffic Data
LTAPI
TCAS Targets
Shared DataRefs for Textual Information
Take Over Camera View of an Aircraft
UDP Broadcast in ForeFlight Data Format
Export Traffic Data