Back to transponders and PCAS etc

[Jaba-who]

Since the actual thread was hijacked and closed down before I got to add my 2 cents I have to start a new one:-)

 

I have to add my support for a transponder (and PCAS).

 

The technical stuff has been mostly correctly posted by several people but what they haven't really stated was the extent of coverage by ground stations (you don't need radar, just ground based transponder interrogating equipment) which is very widespread across even outback Oz. I do lots of outback flying and I am regularly noticing the transponder replying to interrogations in some very outback locations. Basically if you are in the vicinity of an RPT route between towns there us a good chance it is serviced by transponder equipment.

 

I can also vouch that the entire eastern seaboard, lots of the inland around regional cities and even lots of parts of Cape York Peninsular are serviced by transponder interrogating equipment. Our group got called by ATC in western NSW one year asking were we a group together as they were receiving a bunch of returns.

 

I have a Zaon XRX and it is quite interesting watching it pick up people even when you would have thought the transponder interrogation was minimal.

 

 

[Jaba-who]

Yep. Sources of interrogation can be either ground or air based (TCAS). Much of my flying is in company with other aircraft so if there is an interrogation source I have had opportunity to see by company aircraft.

 

You can sometimes get a hint it might be aircraft based. I have been flying in company with another aircraft way out in the boonies - no signal seen. Then suddenly he comes up on the PCAS and my own transponder is seen to be responding as well. Then disappears after a while. Not anywhere near a ground station so assume it was an over flyer.

 

If the signal is solid for long period of time it is probably a ground station that's triggering.

 

When ATC calls you well you know it's ground based. :-)

 

My biggest problem with PCAS has been false positive signals. Ghosting is quite common. Have to look at the distance and height of the threat. If they jump around it's probably a ghost ......... Probably. But I look hard anyway!

 

 

[mkennard]

My PCAS definitely has ghosting. Can initially give you a jolt as there seems to be an aircraft way to close for comfort. Been thinking of getting an external aerial for it but not sure how much difference that will make. Mine appears on my skyview so it's easier to spot than reading a little screen. Working on the sound part as well.

 

 

[Vev]

Thanks Ig. Pity really, I was hoping to get away with the mrx. :rolleyes:

Hi Don,

 

I've had an MRX in my jab for a couple of years now .... it works fine in terms of alerting me to a nearby ac.

 

As for direction .... I look out the window and look for it.

 

Cheers

 

Vev

 

 

[jakej]

As for direction .... I look out the window and look for it.

 

Cheers

 

Vev

 

That's a good idea Vev, especially helpful for spotting those that don't have a transponder or have one turned off

 

Jake J

 

 

[mkennard]

This is assuming they have a transponder and it's turned on. I like a second pair of eyes helping me. My partner is excellent at picking up aircraft that I miss, well miss seeing not miss hitting. Coming back into Sydney through the training area into Camden it's good but there can be a lot of warnings as you can imagine. That's when I turn off the audible warning.

 

 

[Jaba-who]

All of the above are correct but I guess there are some comments to be made.

 

On MRX - XRX difference. MRX is about 1/3 the price. But XRX tells you where the conflicting ACFT is ( direction, distance height and whether it is climbing or descending into your bit of airspace The MRX gives that except the direction and I can tell you from 2 near misses (which is why I spent the money on a PCAS ) that you don't always have time to wonder which direction the conflict is coming - you need to be told so you can look immediately. I have a friend who has an MRX who is looking to offload it to buy an XRX because he's found having no indicator of direction a problem. He has a low- wing with bubble canopy with great views up but poor down. I have a jab which has pretty good views in some directions but there are plenty of directions where you have no vision. And All ACFT have blind spots somewhere so relying on the conflicts only ever being where you can see them is being optimistic.

 

After over ten years of flying on aero club tours around Oz i reckon that relying on the Mark 1 eyeball alone is a fools paradise. We fly often ten + aircraft in company and we talk to each other and tell each other exactly where we are (using GPS ) and you often just can not see small GA ACFT even when you know they are there.

 

The XRX will also connect to a number of screened avionics displays to incorporate the returns on the display. I'm not sure if the MRX will do the same. I don't think it does.

 

 

[Jaba-who]

Haven't seen that. I'll let him know and he can chase it up. Thanks.