A few days ago I was getting ready to do a cross country with one of
my students. This was going to be his first cross country, so the
focus was going to be on pilotage, dead reckoning, planning, cockpit
management, and stuff like that. I was going to save the flight
following, flight plan, class C stuff for a later lesson.

He planned to a class D airport about 25 miles northeast of SFO, away
from the Bravo, but still under the mode C ring. He seemed to have his
stuff together, so after a few checkpoints I decided to go ahead and
call up Norcal to get following. I thought "might as well".

So I show my student how to get the frequency out of the AF/D. Then I
give them a call, tell our location, altitude, type, etc. The
controller gives us a squwak code and wait for him to tell us he has
us on radar. A few seconds later he calls us back and tells us to
recycle our transponder, as he isn't seeing anything on the scope. I
recycle it a few times, check the circuit breaker, and anything else I
can think to do. He comes back saying he doesn't have us, and I just
respond, "thanks anyway".

We ended up diverting somewhere else, did a few short/soft fields,
then called it a day. If we hadn't called flight following, we would
had never known about the transponder not working, and would have
violated some airspace. Scary stuff. It makes me nervous, as I did
another student's first cross country to class E airport underlying a
class C a few days prior (in a different plane). We made sure the mode
C was on and I even monitored their approach frequency, but I didn't
call them. It really makes you wonder... I just think it's distracting
having to constantly listen for your call sign while you're trying to
explain important stuff to your student.

Anyways, I was wondering, would it be a dumb idea to just call up a
radar facility to just ask if they can see your transponder?

--"Norcal center, this is cessna XXXX 10 miles south of blah blah,
6000 feet VFR, I don't want advisories, but can you tell me if you can
see my transponder"
--"cessna XXXX, sqwak 4545 and ident"
--"cessna XXX yes I see you"
--"ok thanks have a good day"

Does anybody do this? Has a problem like this ever been encountered by
anyone else? Is there any other way to check that your transponder is
working before you enter airspace?

buttman wrote:


> Does anybody do this? Has a problem like this ever been encountered by
> anyone else? Is there any other way to check that your transponder is
> working before you enter airspace?

It's common. Many towers have displays remoted from radar facilities
many miles away. If you are behind hills, etc., they will never see you,
and a lot of aircraft owners unnecessarily freak out about
"non-functional" transponders because of this. Danbury, CT (DXR), is an
excellent example, remoted from HPN with a severe hill between.

Rip

buttman > wrote in news:1180576884.287284.107090
@g37g2000prf.googlegroups.com:

> A few days ago I was getting ready to do a cross country with one of
> my students. This was going to be his first cross country, so the
> focus was going to be on pilotage, dead reckoning, planning, cockpit
> management, and stuff like that. I was going to save the flight
> following, flight plan, class C stuff for a later lesson.
>
> He planned to a class D airport about 25 miles northeast of SFO, away
> from the Bravo, but still under the mode C ring. He seemed to have his
> stuff together, so after a few checkpoints I decided to go ahead and
> call up Norcal to get following. I thought "might as well".
>
> So I show my student how to get the frequency out of the AF/D. Then I
> give them a call, tell our location, altitude, type, etc. The
> controller gives us a squwak code and wait for him to tell us he has
> us on radar. A few seconds later he calls us back and tells us to
> recycle our transponder, as he isn't seeing anything on the scope. I
> recycle it a few times, check the circuit breaker, and anything else I
> can think to do. He comes back saying he doesn't have us, and I just
> respond, "thanks anyway".
>
> We ended up diverting somewhere else, did a few short/soft fields,
> then called it a day. If we hadn't called flight following, we would
> had never known about the transponder not working, and would have
> violated some airspace. Scary stuff. It makes me nervous, as I did
> another student's first cross country to class E airport underlying a
> class C a few days prior (in a different plane). We made sure the mode
> C was on and I even monitored their approach frequency, but I didn't
> call them. It really makes you wonder... I just think it's distracting
> having to constantly listen for your call sign while you're trying to
> explain important stuff to your student.
>
> Anyways, I was wondering, would it be a dumb idea to just call up a
> radar facility to just ask if they can see your transponder?

Are oyu sure you're an instructor?


Bertie

"buttman" > wrote in message
oups.com...
>
> A few days ago I was getting ready to do a cross country with one of
> my students. This was going to be his first cross country, so the
> focus was going to be on pilotage, dead reckoning, planning, cockpit
> management, and stuff like that. I was going to save the flight
> following, flight plan, class C stuff for a later lesson.
>
> He planned to a class D airport about 25 miles northeast of SFO, away
> from the Bravo, but still under the mode C ring. He seemed to have his
> stuff together, so after a few checkpoints I decided to go ahead and
> call up Norcal to get following. I thought "might as well".
>
> So I show my student how to get the frequency out of the AF/D. Then I
> give them a call, tell our location, altitude, type, etc. The
> controller gives us a squwak code and wait for him to tell us he has
> us on radar. A few seconds later he calls us back and tells us to
> recycle our transponder, as he isn't seeing anything on the scope. I
> recycle it a few times, check the circuit breaker, and anything else I
> can think to do. He comes back saying he doesn't have us, and I just
> respond, "thanks anyway".
>
> We ended up diverting somewhere else, did a few short/soft fields,
> then called it a day. If we hadn't called flight following, we would
> had never known about the transponder not working, and would have
> violated some airspace. Scary stuff. It makes me nervous, as I did
> another student's first cross country to class E airport underlying a
> class C a few days prior (in a different plane). We made sure the mode
> C was on and I even monitored their approach frequency, but I didn't
> call them. It really makes you wonder... I just think it's distracting
> having to constantly listen for your call sign while you're trying to
> explain important stuff to your student.
>
> Anyways, I was wondering, would it be a dumb idea to just call up a
> radar facility to just ask if they can see your transponder?
>
> --"Norcal center, this is cessna XXXX 10 miles south of blah blah,
> 6000 feet VFR, I don't want advisories, but can you tell me if you can
> see my transponder"
> --"cessna XXXX, sqwak 4545 and ident"
> --"cessna XXX yes I see you"
> --"ok thanks have a good day"
>
> Does anybody do this? Has a problem like this ever been encountered by
> anyone else? Is there any other way to check that your transponder is
> working before you enter airspace?
>

It's not at all unusual for aircraft to call for a transponder and encoder
check.

In article . com>,
buttman > wrote:
>
>So I show my student how to get the frequency out of the AF/D. Then I
>give them a call, tell our location, altitude, type, etc. The
>controller gives us a squwak code and wait for him to tell us he has
>us on radar. A few seconds later he calls us back and tells us to
>recycle our transponder, as he isn't seeing anything on the scope. I
>recycle it a few times, check the circuit breaker, and anything else I
>can think to do. He comes back saying he doesn't have us, and I just
>respond, "thanks anyway".

Was the ident light blinking? How low where you? There are some
pretty good sized hills around CCR, so you might have been below
radar coverage. I'm not sure if Norcal has a feed from Travis,
but the controller would probably know if you where in an area he
can't see and hand you off to Travis if that was the case.

John
--
John Clear - http://www.clear-prop.org/

> Is there any other way to check that your transponder is
> working before you enter airspace?

I sometimes ask for a Mode C check.
It checks the encoding altitmeter in addition to general operation.

Tony

--

Tony Roberts
PP-ASEL
VFR OTT
Night
Cessna 172H C-GICE

On May 30, 9:05 pm, (John Clear) wrote:
> In article . com>,
>
> buttman > wrote:
>
> >So I show my student how to get the frequency out of the AF/D. Then I
> >give them a call, tell our location, altitude, type, etc. The
> >controller gives us a squwak code and wait for him to tell us he has
> >us on radar. A few seconds later he calls us back and tells us to
> >recycle our transponder, as he isn't seeing anything on the scope. I
> >recycle it a few times, check the circuit breaker, and anything else I
> >can think to do. He comes back saying he doesn't have us, and I just
> >respond, "thanks anyway".
>
> Was the ident light blinking? How low where you? There are some
> pretty good sized hills around CCR, so you might have been below
> radar coverage. I'm not sure if Norcal has a feed from Travis,
> but the controller would probably know if you where in an area he
> can't see and hand you off to Travis if that was the case.
>
> John
> --
> John Clear - http://www.clear-prop.org/

ident light was not blinking, but some of these planes have a real dim
ident light and the sun was behind us.

Also, we were at about 3000 feet and just south of Modesto. I don't
think radar coverage was the issue.

On May 30, 9:18 pm, tony roberts > wrote:
> > Is there any other way to check that your transponder is
> > working before you enter airspace?
>
> I sometimes ask for a Mode C check.
> It checks the encoding altitmeter in addition to general operation.
>
> Tony
>
> --
>
> Tony Roberts
> PP-ASEL
> VFR OTT
> Night
> Cessna 172H C-GICE

huh

I've never heard someone ask for such a thing. What do you say, just
your tailnumber and location and they come back with "yeah I see you",
or is it more involved than that?

> huh
>
> I've never heard someone ask for such a thing. What do you say, just
> your tailnumber and location and they come back with "yeah I see you",
> or is it more involved than that?

If it's busy I don't say anything.
If I'm out at 2100 hours, and the tower staff are sitting there bored
out of their minds, I'll sometimes call, "Kelowna Tower, Cessna 172 Golf
India Charlie Echo requesting Mode C check - I have 4200 ft" and they
will respond, "India Charlie Echo Altimeter setting is 29.96 - we read
4350ft." Then I know that although I am out, I am still legal.
If of course the call India Charlie Echo we read 4550 feet then I know
to have my modre C encoder checked before I fly through any serious
airspace.

HTH

Tony

--

Tony Roberts
PP-ASEL
VFR OTT
Night
Cessna 172H C-GICE

tony roberts wrote:
>
> I sometimes ask for a Mode C check.
> It checks the encoding altitmeter in addition to general operation.

Our plane flies in Bravo/Charlie/IFR enough that we know ours works.

However, we went through a spell where we were told by ATC that they
were getting double returns from us. Our favorite avionics guy checked
it twice with nothing found. The double return would happen in a
relatively specific geographical area. We would often get asked if we
had multiple transponders in the aircraft.

The problem disappeared, and we've since met others who had been told of
double returns. We've chalked it up as a since-repaired FAA radar /
computer issue.

I'd simply ask ATC for checks, as Tony mentioned.

tony roberts wrote:
> If it's busy I don't say anything.
> If I'm out at 2100 hours, and the tower staff are sitting there bored
> out of their minds, I'll sometimes call, "Kelowna Tower, Cessna 172 Golf
> India Charlie Echo requesting Mode C check - I have 4200 ft" and they
> will respond, "India Charlie Echo Altimeter setting is 29.96 - we read
> 4350ft." Then I know that although I am out, I am still legal.
> If of course the call India Charlie Echo we read 4550 feet then I know
> to have my modre C encoder checked before I fly through any serious
> airspace.



I'm surprised that nobody's mentioned the old trick about how to avoid getting
busted on an altitude. Upon being questioned about your altitude, you note
you're off by 300 feet (or whatever). Announce you're recycling your
transponder, turn it off, climb or dive like a banshee, turn it back on a few
moments later as you establish yourself where you were supposed to be in the
first place.

Of course I have no personal experience with this technique as I've been an
accurate pilot.




--
Mortimer Schnerd, RN
mschnerdatcarolina.rr.com

B A R R Y wrote:

>
> The problem disappeared, and we've since met others who had been told of
> double returns. We've chalked it up as a since-repaired FAA radar /
> computer issue.

There's a spot I fly over that almost always generates a spurious TIS
target. I suspect it's a similar problem.

> There's a spot I fly over that almost always generates a spurious TIS
> target. I suspect it's a similar proble

The TIS response may also be the boundry of a sector. Is the spurious
response right at your own location?

Jose
--
There are two kinds of people in the world. Those that just want to
know what button to push, and those that want to know what happens when
they push the button.
for Email, make the obvious change in the address.

On May 30, 7:01 pm, buttman > wrote:

>
> Does anybody do this? Has a problem like this ever been encountered by
> anyone else? Is there any other way to check that your transponder is
> working before you enter airspace?

I do it every year after annual (since all the antennas have been
messed with). Just call approach/center and ask for a transponder
check.

-Robert

Yes it, reJose wrote:
>> There's a spot I fly over that almost always generates a spurious TIS
>> target. I suspect it's a similar proble
>
> The TIS response may also be the boundry of a sector. Is the spurious
> response right at your own location?
>
Yes, it reports a target same altitude and location as me.

> Yes, it reports a target same altitude and location as me.

Same thing happens to us. I think what you are seeing is the adjacent
sector reporting your own airplane as you transition across the
boundary. First couple of times does cause the seat to crease though.

Jose
--
There are two kinds of people in the world. Those that just want to
know what button to push, and those that want to know what happens when
they push the button.
for Email, make the obvious change in the address.

On May 31, 6:44 am, B A R R Y > wrote:
> tony roberts wrote:
>
> > I sometimes ask for a Mode C check.
> > It checks the encoding altitmeter in addition to general operation.
>
> Our plane flies in Bravo/Charlie/IFR enough that we know ours works.
>
> However, we went through a spell where we were told by ATC that they
> were getting double returns from us. Our favorite avionics guy checked
> it twice with nothing found. The double return would happen in a
> relatively specific geographical area. We would often get asked if we
> had multiple transponders in the aircraft.
>
> The problem disappeared, and we've since met others who had been told of
> double returns. We've chalked it up as a since-repaired FAA radar /
> computer issue.
>
> I'd simply ask ATC for checks, as Tony mentioned.

There is a great article on the web (I'll try and track it down) about
how this happens in radar facilities with multiple radars feeding the
presentation the controller is seeing. Memphis Center "use" to have
the problem just north of Dyersburg, it was the most notorious in the
country I was told...and it took some effort to fix it.

It has to do when the computer that is processing all of this gets
"confused" because of the time and angle of how the returns from the
various radar sites are coming to it.

Robert

"buttman" > wrote in message
ups.com...
>
> ident light was not blinking, but some of these planes have a real dim
> ident light and the sun was behind us.
>
> Also, we were at about 3000 feet and just south of Modesto. I don't
> think radar coverage was the issue.

Remember that the light should respond to calls made from other
TCAS-equipped aircraft. If you think there should have been sufficient
airline traffic ovehead to trigger the light, you might want to check the
transponder.

I just upgraded to a solid state transponder after years of troubleshooting
intermittent problems in my KT-76A (including bench checks, antenna
cleaning, mode-c replacements) and the transition to solid state seemed to
have fixed the problem. To answer the original post, during all this time, I
called various ATC facilities to check my mode C with no pushback from them.

Marco