TCAS

[tnowak]

I know this isn't really anything to do with PAW but expect someone will know the answer.
Regarding TCAS fitted to CAT and big GA, what does TCAS process to determine if there is a potential flight risk?

My question is prompted by an Airprox report, regarding glider tug aircraft, in the spring 2018 issue of the GASCO Flight Safety magazine.
The recommendation (regarding a specific Airprox) was for tug aircarft to be transponder equipped.

So, I have a Trig Mode S transponder and ADS-B out in my aeroplane. My ADS-B out has a SIL=0 setting.

Will TCAS respond to my transponder transmissions if a flight risk is probable?
I don't think my ADS-B Out data will be processed due to the SIL flag setting.

Thanks

Tony

[AlanB]

So, I have a Trig Mode S transponder and ADS-B out in my aeroplane. My ADS-B out has a SIL=0 setting.

Will TCAS respond to my transponder transmissions if a flight risk is probable?
I don't think my ADS-B Out data will be processed due to the SIL flag setting.

Thanks

Tony

This is a “Wikipedia” on TCAS.

 Basically the answer is that TCAS will respond to your mode S transponder but not the ADS-B output and provide a resolution for CAT to avoid the conflict.

Unlike the general 1090 Rx in GA aircraft the CAT TCAS is an interrogator so will determine a range an bearing from them and if you have mode C a relative altitude.

[tnowak]

Alan,

Thanks - didn't think to check online first!
The thing I couldn't figure out is how TCAS was able to determin the location of the "conflict" without the "conflict" transmitting position data.
I didn't realise that TCAS equipment involves a directional antenna for determining direction information.
Obviously a bit more sophisticated than my basic transponder antenna!

Tony