Out-of-calibration transponder operation

[Jim Stewart]

I was thumbing through the FAR/AIM last night,
trying to fall asleep and I noticed something
that I couldn't understand.

It appeared (in my half-asleep state) that the
FAR says not to operate an out-of-calibration
transponder at all, and the FAR says to operate
it with altitude reporting off.

On the face of it, the FAR would have the authority
of law behind it. Any clarification?

[Jim Stewart]

Jim Stewart wrote:
> I was thumbing through the FAR/AIM last night,
> trying to fall asleep and I noticed something
> that I couldn't understand.
>
> It appeared (in my half-asleep state) that the
> FAR says not to operate an out-of-calibration
> transponder at all, and the FAR says to operate
^
Should say AIM
> it with altitude reporting off.
>
> On the face of it, the FAR would have the authority
> of law behind it. Any clarification?

[JGalban via AviationKB.com]

Jim Stewart wrote:
>> I was thumbing through the FAR/AIM last night,
>> trying to fall asleep and I noticed something
>[quoted text clipped - 3 lines]
>> FAR says not to operate an out-of-calibration
>> transponder at all, and the FAR says to operate
> ^
> Should say AIM
>> it with altitude reporting off.
>>
>> On the face of it, the FAR would have the authority
>> of law behind it. Any clarification?

Since you didn't reference any particular passages, I'll take a blind stab
at this one.

There is an FAR that says you should not operate a transponder that has not
had a certification within the last 24 months. While FARs don't have the
authority of law, they do have the authority of regulation.

I'm guessing that the AIM reference you're talking about is the one that
refers to your turning off altitude reporting if ATC notes that the reported
altitude differs from actual altitude. In that case, it's a temporary
measure to allow ATC to contiue seeing your aircraft on their scope on that
particular flight. You still need to get the problem checked out. You can't
just keep flying around with the Mode/C turned off.

John Galban=====>N4BQ (PA28-180)

--
Message posted via AviationKB.com
http://www.aviationkb.com/Uwe/Forums.aspx/aviation/200709/1

[Gig 601XL Builder]

JGalban via AviationKB.com wrote:
>
> You can't just keep flying around with the
> Mode/C turned off.
>

You can if you aren't in an area that requires Mode/C can't you?

[Mark Hansen]

On 09/13/07 12:33, Gig 601XL Builder wrote:
> JGalban via AviationKB.com wrote:
>>
>> You can't just keep flying around with the
>> Mode/C turned off.
>>
>
> You can if you aren't in an area that requires Mode/C can't you?
>
>

Have a look at FAR 91.215, especially paragraph (c): Transponder-on operation:

"While in the airspace as specified in paragraph (b) of this section or in all
controlled airspace, each person operating an aircraft equipped with an operable
ATC transponder maintained in accordance with §91.413 of this part shall operate
the transponder, including Mode C equipment if installed, and shall reply on the
appropriate code or as assigned by ATC."

Although paragraph (b) refers to the airspace where Mode C is required, I read the
"or" in the above sentence to mean: "if you're in controlled airspace (A, B, C, D
or E), and your transponder support Mode C, you must have Mode C turned on."



--
Mark Hansen, PP-ASEL, Instrument Airplane, USUA Ultralight Pilot
Cal Aggie Flying Farmers
Sacramento, CA

[JGalban via AviationKB.com]

Gig 601XL Builder wrote:
>> You can't just keep flying around with the
>> Mode/C turned off.
>
>You can if you aren't in an area that requires Mode/C can't you?

I guess it depends on how you interpret the letter of the law. I think
it's clear that you're OK in class G airspace. FAR 91.215(c) says you
should have it on (with mode C) in all controlled airspace if so equipped and
operable. I suppose you could get out of the requirement by claiming that
the mode C is not operable. In that case, I guess you'd have to placard the
unit in accordance with the regs.

Here's FAR 91.215(c) :

"Transponder-on operation. While in the airspace as specified in paragraph (b)
of this section or in all controlled airspace, each person operating an
aircraft equipped with an operable ATC transponder maintained in accordance
with Sec. 91.413 of this part shall operate the transponder, including Mode C
equipment if installed, and shall reply on the appropriate code or as
assigned by ATC."

In real life, if you're operating in an area where Mode C is required and
your Mode C isn't working, you will often get a letter from the FSDO asking
what you did to rectify the situation.


John Galban=====>N4BQ (PA28-180)

--
Message posted via AviationKB.com
http://www.aviationkb.com/Uwe/Forums.aspx/aviation/200709/1

[Jim Stewart]

JGalban via AviationKB.com wrote:
> Gig 601XL Builder wrote:
>>> You can't just keep flying around with the
>>> Mode/C turned off.
>> You can if you aren't in an area that requires Mode/C can't you?
>
> I guess it depends on how you interpret the letter of the law. I think
> it's clear that you're OK in class G airspace. FAR 91.215(c) says you
> should have it on (with mode C) in all controlled airspace if so equipped and
> operable. I suppose you could get out of the requirement by claiming that
> the mode C is not operable. In that case, I guess you'd have to placard the
> unit in accordance with the regs.
>
> Here's FAR 91.215(c) :
>
> "Transponder-on operation. While in the airspace as specified in paragraph (b)
> of this section or in all controlled airspace, each person operating an
> aircraft equipped with an operable ATC transponder maintained in accordance
> with Sec. 91.413 of this part shall operate the transponder, including Mode C
> equipment if installed, and shall reply on the appropriate code or as
> assigned by ATC."
>
> In real life, if you're operating in an area where Mode C is required and
> your Mode C isn't working, you will often get a letter from the FSDO asking
> what you did to rectify the situation.

Class G is what I was wondering about. With
an out-of-calibration transponder in G is it
better to leave it off or put it in normal
mode?

[kontiki]

Jim Stewart wrote:
>
> Class G is what I was wondering about. With
> an out-of-calibration transponder in G is it
> better to leave it off or put it in normal
> mode?

If all you are flying in is class G then it really doesn't matter.
ATC probably won't be even seeing you on radar in class G and you
won't be talking to them anyway.

[Ray Andraka]

in Class G airspace, ATC radar in most cases won't illuminate your
transponder, so it won't reply anyway, so as far as ATC is concerned it
probably doesn't matter if you have it on or not. However, TCAS
equipped aircraft will interrogate your transponder, so to be visible to
them you might want to keep it on mode3/A so that it doesn't report a
misleading altitude but does return a reply.

[BT]

>
> If all you are flying in is class G then it really doesn't matter.
> ATC probably won't be even seeing you on radar in class G and you
> won't be talking to them anyway.

There is a lot of Class G out here in the west... and a lot of it in radar
coverage..

B

[Jim Stewart]

Ray Andraka wrote:
> in Class G airspace, ATC radar in most cases won't illuminate your
> transponder, so it won't reply anyway, so as far as ATC is concerned it
> probably doesn't matter if you have it on or not. However, TCAS
> equipped aircraft will interrogate your transponder, so to be visible to
> them you might want to keep it on mode3/A so that it doesn't report a
> misleading altitude but does return a reply.

Well, not where I live. My airport is
under Sac Intl. class C and I'm less than
10 miles away from 2 class D airports.
Beal is about 25 miles north and class C.

The transponder lamp is blinking almost
continuously whenever the transponder is
on.

[Ray Andraka]

Jim Stewart wrote:

> Ray Andraka wrote:
>
>> in Class G airspace, ATC radar in most cases won't illuminate your
>> transponder, so it won't reply anyway, so as far as ATC is concerned
>> it probably doesn't matter if you have it on or not. However, TCAS
>> equipped aircraft will interrogate your transponder, so to be visible
>> to them you might want to keep it on mode3/A so that it doesn't report
>> a misleading altitude but does return a reply.
>
>
> Well, not where I live. My airport is
> under Sac Intl. class C and I'm less than
> 10 miles away from 2 class D airports.
> Beal is about 25 miles north and class C.
>
> The transponder lamp is blinking almost
> continuously whenever the transponder is
> on.


OK, my bad. I was thinking of the larger areas of class G in the
mountains out west, but someone else here tells me there is radar
coverage over a significant part of that too. When I flew to Taos about
10 years back, I remember there being no radar coverage once you got
below the peaks, and I was going off that limited experience.

My point though was that if your transponder is working but not
squawking altitude correctly, leaving it on but in the Mode 3/A position
still has some benefit, even if you are outside of radar coverage.