X-Plane Transponder Modes

[Chris Beckett 1395189]

I am sorry this won't be a brief description but this is kinda weird. The X-Plane SDK lists the standard values for the transponder_mode dataref as (Off=0, Standby=1, On=2, Test=3). It seems however that some aircraft use custom transponder values. For example, the Aerobask Viperjet models the GTX330 transponder and sets the X-Plane transponder mode as (Off=0, Standby=1, On=2, Alt=3).

 

Previously when flying on Vatsim using XSB and setting the ViperJet transponder to ALT mode (transponder_mode = 3), ATC would see you in Mode C. Conversely, I have flown other aircraft (e.g. the AOA Osprey) using XSB where the X-Plane transponder mode was ON=2, and ATC told me they could not see me squawking mode C. I had to write a custom LUA script to set the transponder_mode = 3 to fly it on Vatsim.

 

Tonight, using the latest xPilot on the upgraded live network, it has been the inverse. In the ViperJet, for example, even though xPilot shows "Mode C" in the UI when the transponder is set to both ON=2, or ALT=3, ATC reported they only saw me squawking mode C when the transponder_mode dataref = 2. When flying the Osprey using my LUA code and transponder_mode = 3, ATC said they could not see me squawking Mode C.

 

So, two observations:

 

#1 - there seems to be a difference with regard to how XSB read and reported the X-Plane transponder mode to Vatsim than the current xPilot beta... and it may cause an issue with potentially many aircraft with regard to how they have modeled their transponders to set the X-Plane transponder dataref.

 

#2 - the current xPilot beta shows "Mode C" in the UI when the X-Plane transponder_mode is either 2 or 3, but Vatsim ATC will only see you squawking Mode C if the transponder_mode = 2.

 

Cheers,

Chris

[Justin Shannon]

Have you tried v1.1.0.1? This fixed an issue with the Toliss Airbus transponder mode and it may help with your issue as well.

[Chris Beckett 1395189]

I did test it with v1.1.0.1. I loaded up at KBOS and had GND verify it for me. In the Aerobask ViperJet, with the transponder in ALT mode (the way I have always flown it before), ATC said they could not see me in Mode C. Behind the scenes, the X-Plane transponder_mode dataref = 3.

 

When I changed the ViperJet transponder from ALT to ON (behind the scenes, transponder_mode = 2), then they reported I was Mode C.