Dual Transponders

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bnunn

Filing Flight Plan
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Sherman, Texas
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Display name:
Bob
I was browsing some Piper Malibu's on Controller.com and noticed that some have dual transponders. Why dual? Is it for redundancy? Or is there a pratical use?
 
My Cardinal's primary transponder is controlled by my CNX-80, and if either the control link or the GPS itself fails, there is no way to control that transponder as it is mounted somewhere in the tailcone, not in the panel. So the previous owner installed a second, panel-mounted transponder. I've had to use it twice now. Having the GPS set your squawk code is a great convenience when it works, but when it doesn't, I definitely appreciate having the backup.
 
Redundancy. We had dual Bendix/King transponders in the Bonanza and would cycle which one we used occasionally. We have dual transponders in the PC12s, and CJ3s at work as well.
 
The consequences of our light g.a. a/c having a transponder failure is not terrible - we continue vfr or maybe have to inconvenience a handful of people who understand equipment failures happen.
For biz a/c and the airlines, the consequences of the only transponder failing are not as tolerable to the people involved. "We can't go because that little box doesn't work?" (I doubt larger a/c can dispatch without a functioning txpdr into rvsm...or caa at all.)
The redundancy provided by the additional expense of several thousand dollars is worthwhile for those flying multimillion dollar a/c....but mostly is not for those in $75,000 a/c.

I have had one fail a couple times in caa and it is really, really nice to just flip that switch and carry on, giving atc only a minimum of angst.
 
Or ATC giving you the minimum of angst back....experience has taught me that the encoder fails more readily than the transponder itself...ask me how I know, and the angst it creates when you get the famous: "I have a phone number for you to call...ready to copy" speech upon landing after the encoder craps out and the class C thinks you're busting their airspace at 2000ft when your actually at 4500ft.
 
azure said:
My Cardinal's primary transponder is controlled by my CNX-80, and if either the control link or the GPS itself fails, there is no way to control that transponder as it is mounted somewhere in the tailcone, not in the panel. So the previous owner installed a second, panel-mounted transponder. I've had to use it twice now. Having the GPS set your squawk code is a great convenience when it works, but when it doesn't, I definitely appreciate having the backup.
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How so?
 
Let'sgoflying! said:
The consequences of our light g.a. a/c having a transponder failure is not terrible - we continue vfr or maybe have to inconvenience a handful of people who understand equipment failures happen.
For biz a/c and the airlines, the consequences of the only transponder failing are not as tolerable to the people involved. "We can't go because that little box doesn't work?" (I doubt larger a/c can dispatch without a functioning txpdr into rvsm...or caa at all.)
The redundancy provided by the additional expense of several thousand dollars is worthwhile for those flying multimillion dollar a/c....but mostly is not for those in $75,000 a/c.

I have had one fail a couple times in caa and it is really, really nice to just flip that switch and carry on, giving atc only a minimum of angst.
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What do you mean by "caa"?
 
Well if you look back through this...or any thread, there are always acronyms and other abbreviations. The question becomes which do we assume everyone knows and which need spelling out. I assumed wrong, my apologies; 30 lashes accepted and I will try to remember to spell more of them out.
 
Let'sgoflying! said:
Well if you look back through this...or any thread, there are always acronyms and other abbreviations. The question becomes which do we assume everyone knows and which need spelling out. I assumed wrong, my apologies; 30 lashes accepted and I will try to remember to spell more of them out.
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Very true, and I think that acronym's and things of that nature are what drive people off of aviation in general. People start talking to them like they know everything about aviation, and those who want to maybe learn are driven off by things they have no idea about. I had never seen caa before, and had to sit and think about it for a while. Makes sense now that I know, but it was new for sure.
 
KSCessnaDriver said:
Wouldn't it just be easier to say Class A airspace, rather than confusing the heck out of people with yet another acronym that really isn't necessary?
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Its crap like that... that caused the healthcare industry to be regulated away from certain abbreviations due to the ambiguity they created. Sometimes with dangerous results.
 
kkoran said:
How so?
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Because it doesn't just set the squawk code; since it's a GPS, it can sense your ground speed. The CNX-80, when the link is working, will set the SBY and ALT modes depending on a user-settable trigger speed. It can also set your code to 7700 or 1200 with a single key stroke (might take 2, since these functions are accessed through a menu). This only works with certain transponders like the SL-70.

It can also control certain Mode S transponders, but I don't have any experience there.
 
I don't browse POA, excuse me, Pilots Of America very often, and post a question even less than that. However, it always amazes me what a good job you guys do in answering and discussing. For a simple question like dual transponders, I have received thoughtful, insightful information. Ok, so I didn't know either what "caa" meant. That's probably because I've never flown in that airspace as a private pilot. I'm instrument rated, have over 1,000 hours and average around 10 hrs/month. but it's all in a single engine plane with a service ceiling of 15,000 feet.

Anyway, I learned more than I asked. Only because you guys don't mind offering up your experience and opinions.

Thanks
 
Bob:

Nice to read that. Come around often.

And don't mind Dave - he sniffs too much Jet-A, as he goes AOK in CAA.
 
bnunn said:
Ok, so I didn't know either what "caa" meant. That's probably because I've never flown in that airspace as a private pilot.
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I didn't know what caa meant either and I spend most of my time there. :dunno:
 
I just figured it had something to do with Canada. I'm going to start doing that, anything I don't understand it must be something to do with Canada :thumbsup:
 
Jeez, I didn't even come up with the darned acronyms - I read it several times -maybe it was on other aviation boards and figured all knew caa, cba, cca, etc. Please don't make a big deal out of this, I have already apologized.

I don't recall being vilified over a minor gaffe like this since....the Red Board. I sure hope.....
 
Let'sgoflying! said:
Jeez, I didn't even come up with the darned acronyms - I read it several times -maybe it was on other aviation boards and figured all knew caa, cba, cca, etc. Please don't make a big deal out of this, I have already apologized.

I don't recall being vilified over a minor gaffe like this since....the Red Board. I sure hope.....
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It's not nearly as bad as some of the jargon the computer geeks here use. :D
 
bigred177 said:
I just figured it had something to do with Canada. I'm going to start doing that, anything I don't understand it must be something to do with Canada :thumbsup:
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That was my philosophy as well, but as of late, Canada makes more sense to me.
 
Let'sgoflying! said:
Jeez, I didn't even come up with the darned acronyms - I read it several times -maybe it was on other aviation boards and figured all knew caa, cba, cca, etc.
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What the devil is "etc"?

bigred177 said:
anything I don't understand it must be something to do with Canada
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Ah, got it, it's Canadian for air traffic control - "EH" TEE CEE . :D
 
Laurie said:
That was my philosophy as well, but as of late, Canada makes more sense to me.
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I second that. The people at the Waskaganish airport treat me pretty well - only problem being they don't sell fuel.
 
Just to reassure y'all that I have not lost proper perspective on what is important (laughing at oneself and the incidents that we come across) I attach my new avatar for your review. I really hacked my hand up last night on a saw and could not let the opportunity pass!
 

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