WHY IS TRANSPONDER PLACARDED NOT FOR USE IN CERTIAN AIRSPACE??

Ron Levy said:
...if it's currently 91.413-certified. If not, it must be left in STBY or OFF.
Note that this is true in the underlying G-space as well as E-space. IOW, there is uncontrolled/G-space where a transponder is required.
Again, this includes Class G airspace, not just controlled airspace.

See 91.215 for details.
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Although a call to ATC prior to the flight can solve any of those problems.
 
When I converted my Sky Arrow to Experimental, the DAR caught that I had somehow let my transponder certification lapse.

The avionics shop I used then was at McGhee Tyson in Knoxville.

I called on the phone to get a waiver for the flight into their Class C. That was easily granted. I then asked if they'd rather me squawk with the out-of-inspection transponder or just leave it off. In this instance, at least, they said best to leave it off, which I did.

Just one data point, is all.
 
FastEddieB said:
I called on the phone to get a waiver for the flight into their Class C. That was easily granted. I then asked if they'd rather me squawk with the out-of-inspection transponder or just leave it off. In this instance, at least, they said best to leave it off, which I did.
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Note that while 91.215 gives ATC various options to allow operations in transponder-required airspace without an operable transponder, 91.413 does not give ATC any authority to allow operation of a non-91.413-compliant transponder.
 
Ron Levy said:
Note that while 91.215 gives ATC various options to allow operations in transponder-required airspace without an operable transponder, 91.413 does not give ATC any authority to allow operation of a non-91.413-compliant transponder.
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Yep!

It seemed like a rational choice that they might prefer an up-to-now perfectly functioning transponder/encoder combo over a nothing-at-all primary target.

So I asked. And got an answer!

Never hurts to ask.
 
You can turn mode C off, on a Garmin 327. Just push the ON button instead of the ALT button. See the 4th page of this pdf file Pilots Guide:

http://www.monticellofc.org/aircraft/GTX327 guide.pdf

Voila, a mode A transponder. No altitude reporting.

If the mode C altitude encoder is out of inspection, it seems to me that the pilot could fly Mode A and this would be better than no transponder, for making your presence known to traffic equipped with interrogating traffic boxes, and making life better for ATC, in airspace where Mode C is not required.
 
I would hope that was common knowledge.

Like for when ATC says, "Stop altitude squawk". Admittedly rare.

My whole combo was out of inspection, so that would not have improved things.
 
FastEddieB said:
I would hope that was common knowledge.
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Well, I mentioned it because someone else here claimed the transponder is only allowed to be off or standby if the altitude encoder is out of inspection. This is not so, because it can be lawfully operated Mode A, in airspace where that's allowed.
 
warthog1984 said:
Unless it was a military or dual-use radar that got a primary return with altitude.
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I think it's safe to assume he contacted an ATC radar facility, in which case it would not show an altitude except with Mode C.
 
NoHeat said:
Well, I mentioned it because someone else here claimed the transponder is only allowed to be off or standby if the altitude encoder is out of inspection. This is not so, because it can be lawfully operated Mode A, in airspace where that's allowed.
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Got it.

Missed the reference.
 
I think the lesson is to not fly a plane with a sticky or other "placard" that you don't fully understand and the potential operational restrictions involved.
 
kkoran said:
Wrong.
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I really thought both PAR and ASR radars showed both azimuth and elevation. I saw one or the other performed, albeit decades ago, and I sure think there were two scopes.

I'll accept that I might be wrong, but something other than a one word correction might help me see the error of my ways! And edify others, of course.

Is it that PAR has elevation and ASR does not?
 
FastEddieB said:
I really thought both PAR and ASR radars showed both azimuth and elevation. I saw one or the other performed, albeit decades ago, and I sure think there were two scopes.

I'll accept that I might be wrong, but something other than a one word correction might help me see the error of my ways! And edify others, of course.

Is it that PAR has elevation and ASR does not?
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ASR displays a "God's Eye" picture of traffic. The data block shows the Mode C altitude.

PARs have elevation and azimuth displays; however, the elevation display doesn't show altitude, it is a graphical depiction of the target's position above or below the glidepath. Assuming the aircraft was on glidepath, one could figure out what elevation (not baro altitude) was at a given a specific distance, but that's not something ATC does (except they know the elevation of the point where the glidepath intercepts the decision altitude). Besides, the OP was at 10,000 MSL, well beyond the range of a PAR.
 
FastEddieB said:
I really thought both PAR and ASR radars showed both azimuth and elevation. I saw one or the other performed, albeit decades ago, and I sure think there were two scopes.

I'll accept that I might be wrong, but something other than a one word correction might help me see the error of my ways! And edify others, of course.

Is it that PAR has elevation and ASR does not?
Click to expand...

Ah, I would assume with two scopes that would be a PAR. With 2 scopes it's easy and cheap to achieve technically. Like I said, it has to have 2 waveguides to do it or a really complex omni directional drive and software, and I still think I need 2 perpendicular wave guides on it.
 
kkoran said:
ASR displays a "God's Eye" picture of traffic. The data block shows the Mode C altitude.

PARs have elevation and azimuth displays; however, the elevation display doesn't show altitude, it is a graphical depiction of the target's position above or below the glidepath. Assuming the aircraft was on glidepath, one could figure out what elevation (not baro altitude) was at a given a specific distance, but that's not something ATC does (except they know the elevation of the point where the glidepath intercepts the decision altitude). Besides, the OP was at 10,000 MSL, well beyond the range of a PAR.
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Yeah, thanks, that's what I was thinking. I had never seen a PAR facility (though used to shoot their approaches) but I had seen an ASR display and that's what I saw.
 
Here's a couple of PAR displays.
images

parScope.png
 
Henning said:
It is if you're heading to the shop to get it fixed.;)
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No, it is not. 91.413 makes no exceptions for aircraft "heading to the shop to get it fixed", and ATC has no authority to waive that rule. If your transponder's certification has expired, it is not legal to turn it past STBY in US airspace, and no waivers to that rule by anyone are authorized. See 91.905.
 
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kkoran said:
ASR displays a "God's Eye" picture of traffic. The data block shows the Mode C altitude.

PARs have elevation and azimuth displays; however, the elevation display doesn't show altitude, it is a graphical depiction of the target's position above or below the glidepath.
Click to expand...

Thanks.

I may have been "misremembering" two separate displays, but I do remember a glide path represented, so it must have been a PAR I was viewing.

It's great that we have so much expertise on this site!
 
FastEddieB said:
Thanks.

I may have been "misremembering" two separate displays, but I do remember a glide path represented, so it must have been a PAR I was viewing.
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If you want to see and hear what a PAR looks and sounds like in operation, grab a copy of the old Jimmy Stewart movie "Strategic Air Command". Near the end of the movie, Stewart is doing a PAR to a base on Okinawa in a B-47, and there are shots of a master sergeant at a PAR console conducting the approach, including shots of the scope.

And fast forward through the scenes with June Allison unless you really like saccharin. :yuk:
 
FastEddieB said:
Thanks.

I may have been "misremembering" two separate displays, but I do remember a glide path represented, so it must have been a PAR I was viewing.

It's great that we have so much expertise on this site!
Click to expand...
I saw a PAR with the elevation and azimuth on separate displays (which looked like 1950s TV tubes) in a Royal Saudi facility.
 
Pretty good PAR scene (albeit without the picture of the scope) in the original Airport movie. There are very slight inaccuracies in the film (such as the use of a frequency in the VOR range as a voice frequency). Most of it is pretty spot on for the era that it was shot in.
 
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