SquawkGear
SquawkGear allows you to fly FlightGear on VATSIM, using a couple of old VATSIM clients, SquawkBox 747 and Advanced Voice Client.
Download SquawkGear from http://squawkgear.wordpress.com
What is VATSIM?
The Virtual Air Traffic Simulation network. "VATSIM is an online community where people can learn and, at the same time, enjoy the pastimes of flight simulation and air traffic control simulation all while making new friends from all over the world." http://www.vatsim.net/vatsim/
History
Curt thinks it worth pushing towards VATSIM connectivity "a bridge... acts as a FG multiplayer server..." - Curt http://www.mail-archive.com/flightgear-devel@lists.sourceforge.net/msg20971.html
"FG users stand to benefit" - Curt http://www.mail-archive.com/flightgear-devel@lists.sourceforge.net/msg12538.html
Similar concept in 2006 (XPlane - FG) http://www.mail-archive.com/flightgear-devel@lists.sourceforge.net/msg03730.html the difference is that SquawkGear interfaces with SB747, not XSB
Tips
There is an undocumented dot command in SB747 that sets the transponder mode:
- .xpdr standby: force squawk-standby, regardless of the code that is set
- .xpdr on: force squawk-mode C (except when code is set as 0000)
- .xpdr auto: squawk-standby when airspeed is below 120 knots, regardless of the code that is set, and mode C when above 120 knots. This feature is meant to reduce ATC's radarscope clutter.
http://www.flightgear.org/forums/viewtopic.php?f=6&t=8816
References
SquawkBox747 by hoppie: http://hoppie.nl/sb747
The 'Broker' referred to by hoppie is the interface that SquawkGear emulates. The API is documented here: http://www.hoppie.nl/broker/downloads/747brok.html
SquawkGear design (from FG forums): http://flightgear.org/forums/viewtopic.php?f=6&t=533&start=60#p66399
Concerning multiplayer (visualisation of network air traffic): http://forums.vatsim.net/viewtopic.php?f=8&t=47884
Concerning the FSD protocol: Download the FSD server source code (for testing a new client): http://flightsim.apollo3.com/files/fs-files-2.html (grab fsd1110.tar.gz)
Concerning the NDA: http://forums.vatsim.net/viewtopic.php?p=350103#p350103 and http://forums.vatsim.net/viewtopic.php?p=350127#p350127
What some people may not realize is that "FSD" predates VATSIM. VATSIM did not create, nor does it "own" the basic FSD design or protocol. VATSIM's FSD is slightly customized, but anyone can develop a pilot client that speaks the basic FSD language without signing VATSIM's NDA. You'll just need to do the NDA before your pilot client can be used on VATSIM. http://forums.vatsim.net/viewtopic.php?p=350127#p350127
X-IvAp is a GPL'd IVAO client for X-Plane.
VAS Project is a GPL'd generic FMS for MSFS, X-Plane and (future) FlightGear.