Do you ever use standby on your transponder?

[Maule Driver]

I don't. It stays on 24/7 (you know what I mean). 1200 unless given a
code. It effectively prevents "Maule, check your transponder" unless
using the wrong code.

I make no attempt to turn it off or go to standby while taxiing or
anything else. I've never been asked to go to standby or otherwise
questioned.

This has been discussed before but I'd suggest the everyone can do this
without causing a problem for anyone.

[Larry Dighera]

On Thu, 15 Sep 2005 17:15:14 GMT, Maule Driver
> wrote in
>::

>I don't.

I was taught to switch from standby upon starting to roll down the
runway for departure. The reasoning that was cited had to do with
radar clutter on the airport surface.

ADS-B may change this practice, however.

[Peter R.]

Maule Driver > wrote:

> I don't. It stays on 24/7 (you know what I mean). 1200 unless given a
> code. It effectively prevents "Maule, check your transponder" unless
> using the wrong code.

I have the Garmin 330 with traffic uplink. I sometimes have to switch it
to STBY just after landing to prevent hearing several traffic alerts caused
by taxiing traffic.

Granted this transponder does have an automatic STBY/ON and visa-versa
switching ability, but upon landing it does not seem to switch quickly
enough to prevent the erroneous traffic alerts.

--
Peter
























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[Orval Fairbairn]

In article >,
Maule Driver > wrote:

> I don't. It stays on 24/7 (you know what I mean). 1200 unless given a
> code. It effectively prevents "Maule, check your transponder" unless
> using the wrong code.
>
> I make no attempt to turn it off or go to standby while taxiing or
> anything else. I've never been asked to go to standby or otherwise
> questioned.
>
> This has been discussed before but I'd suggest the everyone can do this
> without causing a problem for anyone.


I set to "Standby" on the ground, to prevent reflections that could
damage the unit.

I also set "Standby" if I am a wingman in a formation (Only Lead
squawks).

[Robert M. Gary]

I think that is a myth. I don't think the computer shows ATC your
signal if your altitude shows you at ground level.

[Robert M. Gary]

Its useful when flying in a flight of two. ATC will ask you to turn it
to standby.

-Robert

[[email protected]]

Orval Fairbairn wrote:
[snip]
> I set to "Standby" on the ground, to prevent reflections that could
> damage the unit.
>
A perhaps ignorant question: What reflects that could damage the unit
and how could it damage the unit?

John
Solo Student

[Mortimer Schnerd, RN]

Larry Dighera wrote:
> I was taught to switch from standby upon starting to roll down the
> runway for departure. The reasoning that was cited had to do with
> radar clutter on the airport surface.



Ditto.




--
Mortimer Schnerd, RN

[Thomas Borchert]

Maule,

On the ground and off the runway mine is on standby. BTW, our GTX330
now handles that automatically (mostly) in conjunction with groundspeed
from the GPS.

--
Thomas Borchert (EDDH)

[Thomas Borchert]

Peter,

> Granted this transponder does have an automatic STBY/ON and visa-versa
> switching ability, but upon landing it does not seem to switch quickly
> enough to prevent the erroneous traffic alerts.
>

You can adjust that. There is a timeout after which it will go to GND
mode after the speed falls below the threshold speed (30 knots is
default, I think). The default delay is 30 seconds, I think, giving you
time to taxi off the runway. But you can set that to zero. Google for
the 330 set-up manual if you don't have it.

--
Thomas Borchert (EDDH)

[Thomas Borchert]

Orval,

> I set to "Standby" on the ground, to prevent reflections that could
> damage the unit.
>

Say again? Or rather, explain that, please.

--
Thomas Borchert (EDDH)

[Steven P. McNicoll]

"Robert M. Gary" > wrote in message
oups.com...
>
> I think that is a myth. I don't think the computer shows ATC your
> signal if your altitude shows you at ground level.
>

It's not a myth. The computer doesn't know where the ground is, it filters
out only whatever it's told to filter out.

[Steven P. McNicoll]

"Orval Fairbairn" > wrote in message
...
>
> I set to "Standby" on the ground, to prevent reflections that could
> damage the unit.
>

What reflections would do that and how?

[Peter R.]

Thomas Borchert > wrote:

> You can adjust that. There is a timeout after which it will go to GND
> mode after the speed falls below the threshold speed (30 knots is
> default, I think). The default delay is 30 seconds, I think, giving you
> time to taxi off the runway.

Thanks, Tom. I will look into changing this value.

--
Peter
























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[Hilton]

Larry Dighera wrote:
> I was taught to switch from standby upon starting to roll down the
> runway for departure.

You were taught to mess with non-essential stuff on the runway? I once flew
with an VFR pilot - he wanted to see what IMC was like - it was a great
flight (lots of IMC) and he did amazingly well in the clouds - I was
impressed. I let him land - right after we touched down, his hands were
moving around the panel so fast I finally just slapped his hands hands and
said "Stop! Do that when we're stopped on a taxiway."

Hilton

[OtisWinslow]

I was taught the old "lights, camera, action" deal. When I'm preparing to
cross the hold
line onto the active runway on goes the landing light, and the xpndr to Mode
C from
Stby. When I cross the hold line after landing .. it's Xpndr to Stby,
landing light
off (unless it's nite), and electric fuel pump off.

..
"Maule Driver" > wrote in message
.. .
>I don't. It stays on 24/7 (you know what I mean). 1200 unless given a
>code. It effectively prevents "Maule, check your transponder" unless using
>the wrong code.
>
> I make no attempt to turn it off or go to standby while taxiing or
> anything else. I've never been asked to go to standby or otherwise
> questioned.
>
> This has been discussed before but I'd suggest the everyone can do this
> without causing a problem for anyone.

[Larry Dighera]

On Thu, 15 Sep 2005 20:04:21 GMT, "Hilton" >
wrote in . net>::

>Larry Dighera wrote:
>> I was taught to switch from standby upon starting to roll down the
>> runway for departure.
>
>You were taught to mess with non-essential stuff on the runway?

I'm not sure I'd characterize it as "non-essential."

I was taught the "Lights, Camera, Action" reminder phrase where
'camera' signifies transponder on. This mantra is to be uttered in
the beginning of the takeoff roll.

Lights: strobe, landing lights, etc.
Camera: transponder
Action: mixture, props, throttle, airspeed alive, ...

Lots more here: http://tinyurl.com/8meqw

[Orval Fairbairn]

In article >,
Thomas Borchert > wrote:

> Orval,
>
> > I set to "Standby" on the ground, to prevent reflections that could
> > damage the unit.
> >
>
> Say again? Or rather, explain that, please.

Most TXP antennae are belly-mounted. They send out a rather strong EM
signal that can reflect off the pavement and overwhelm the receiver
portion of the TXP, possibly damaging it.

[Newps]

Larry Dighera wrote:

> On Thu, 15 Sep 2005 17:15:14 GMT, Maule Driver
> > wrote in
> >::
>
>
>>I don't.
>
>
> I was taught to switch from standby upon starting to roll down the
> runway for departure. The reasoning that was cited had to do with
> radar clutter on the airport surface.
>
> ADS-B may change this practice, however.

The change was made eons ago. There's no reason to turn the transponder
to STBY anymore.

[Newps]

Orval Fairbairn wrote:


>
>
> I set to "Standby" on the ground, to prevent reflections that could
> damage the unit.


??? Now there's a new one.

[George Patterson]

Maule Driver wrote:
> I don't.

I used to after first startup, but it's an unpleasant feeling to be flying
around near New York and realize that the xpndr has been on standby for the last
half hour.

George Patterson
Give a person a fish and you feed him for a day; teach a person to
use the Internet and he won't bother you for weeks.

[Hilton]

Larry,

> I was taught the "Lights, Camera, Action" reminder phrase where
> 'camera' signifies transponder on. This mantra is to be uttered in
> the beginning of the takeoff roll.
>
> Lights: strobe, landing lights, etc.
> Camera: transponder
> Action: mixture, props, throttle, airspeed alive, ...

My suggestion would be strobes, landing light, transponder before taxiing
onto the runway - you do want to be very visible on the runway too. Also
get the mixture and props. The only items when are the runway are throttle
and airspeed alive - also look for other aircraft etc, think about abort
procedures, how your take off roll is progressing (I have a good story on
this one) etc... I don't like to be fiddling with stuff during the takeoff
roll because there is so much other important stuff to do and to think
about, also, when you fly complex aircraft... Well there's this pesky
little lever that also finds its way into the FAA accident reports. :)

The same goes for landing but in reverse; i.e. don't touch anything until
stopped on a taxiway (or something similar) - basically not on the runway.

Just my opinion.

Hilton

[Jay Masino]

Orval Fairbairn > wrote:
> Most TXP antennae are belly-mounted. They send out a rather strong EM
> signal that can reflect off the pavement and overwhelm the receiver
> portion of the TXP, possibly damaging it.

I would be surprised if most modern transponders don't protect against
this themselves by blanking the receiver during the transmit.

--- Jay


--
__!__
Jay and Teresa Masino ___(_)___
http://www2.ari.net/jmasino ! ! !
http://www.OceanCityAirport.com
http://www.oc-Adolfos.com

[Longworth]

Just last week, we forgot to put the transponder on standby after
landing and were asked by the ATC to do so.

Hai Longworth

[Andrew Sarangan]

I agree with Hilton. Checking the transponder is an unnecessary distraction
during a takeoff. You should be watching for other traffic and your engine
gauges. If the transponder is off, you will find out sooner or later. Same
with lights or strobes. But if you miss a low oil pressure reading, or a
conflicting traffic, the outcome may not be so good.


Larry Dighera > wrote in
:

> On Thu, 15 Sep 2005 20:04:21 GMT, "Hilton" >
> wrote in . net>::
>
>>Larry Dighera wrote:
>>> I was taught to switch from standby upon starting to roll down the
>>> runway for departure.
>>
>>You were taught to mess with non-essential stuff on the runway?
>
> I'm not sure I'd characterize it as "non-essential."
>
> I was taught the "Lights, Camera, Action" reminder phrase where
> 'camera' signifies transponder on. This mantra is to be uttered in
> the beginning of the takeoff roll.
>
> Lights: strobe, landing lights, etc.
> Camera: transponder
> Action: mixture, props, throttle, airspeed alive, ...
>
> Lots more here: http://tinyurl.com/8meqw

[TripFarmer]

My friend did the other day when we flew down to Gulfport to
deliver medical supplies. We went as a flight of two so they
had my friend squawk "Standby" as I was the lead plane.


Trip

In article >, says...
>
>I don't. It stays on 24/7 (you know what I mean). 1200 unless given a
>code. It effectively prevents "Maule, check your transponder" unless
>using the wrong code.
>
>I make no attempt to turn it off or go to standby while taxiing or
>anything else. I've never been asked to go to standby or otherwise
>questioned.
>
>This has been discussed before but I'd suggest the everyone can do this
>without causing a problem for anyone.

[Brien K. Meehan]

I set mine to TEST during my pre-flight checklist, then right back to
ALT.

The only time it's ever been on STBY is when an instructor insisted
that it's really important to do so, and set it himself. That was a
red flag. He didn't work for me much longer.

[Larry Dighera]

On Thu, 15 Sep 2005 18:52:49 -0500, Andrew Sarangan
> wrote in
>::

>Checking the transponder is an unnecessary distraction during a takeoff.

The controller says, "Cherokee 12X cleared for takeoff."

And you reach over and twist the transponder knob, apply takeoff
power, and the "distraction" is gone. It's not a very big deal.

>You should be watching for other traffic and your engine gauges.

Right. Those are some of the things that should happen, and there's
nothing to prevent them.

> If the transponder is off, you will find out sooner or later.

Absolutely.

>Same with lights or strobes.

Umm, not necessarily. If it's day VFR/VMC, and you want to burn a
landing/taxi light to enhance conspicuity and discourage bird strikes,
you may not become aware of the fact that the light is off.

>But if you miss a low oil pressure reading, or a conflicting traffic,
>the outcome may not be so good.

True. But I don't see how twisting the transponder knob before adding
power interferes with those things.

[Jay Honeck]

> I make no attempt to turn it off or go to standby while taxiing or
> anything else. I've never been asked to go to standby or otherwise
> questioned.

Standby gets used only:

a) At OSH, per the NOTAM.

and

b) When flying as a flight of two.

Otherwise, it may as well be soldered "on"...
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Andrew Sarangan]

Larry Dighera > wrote in
:


>
> True. But I don't see how twisting the transponder knob before adding
> power interferes with those things.


In fact I would recommend to turn the transponder on before even getting on
the runway. However, in an earlier post I thought you were recommending to
turn the transponder at the beginning of the takeoff roll, which implied
turning the knob while accelerating down the runway. That is what I was
disagreeing with. I now see what you were getting at.

[Peter R.]

George Patterson > wrote:

> I used to after first startup, but it's an unpleasant feeling to be flying
> around near New York and realize that the xpndr has been on standby for the last
> half hour.

Rumor has it that many a NY-based CFI would do just that to avoid getting
busted when their students crossed over into the NY class B airspace.

A pilot mentor of mine used to fly corporate into Teterboro in an MU-2 and
he told me he was always nervous on approach into TEB for fear of the GA
aircraft with the transponder turned off.

--
Peter


















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[tony roberts]

I have had landing aircraft report a near miss when I left my
transponder on accidentally..
At my little Class D airport our rule is standby to warm it up - it does
take a few minutes (at least mine does) - and on upon takeoff.

Tony
C-GICE

In article >,
Maule Driver > wrote:

> I don't. It stays on 24/7 (you know what I mean). 1200 unless given a
> code. It effectively prevents "Maule, check your transponder" unless
> using the wrong code.
>
> I make no attempt to turn it off or go to standby while taxiing or
> anything else. I've never been asked to go to standby or otherwise
> questioned.
>
> This has been discussed before but I'd suggest the everyone can do this
> without causing a problem for anyone.




--

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

[[email protected]]

Mine is on standby during taxiing and when I'm flying below Amsterdam
TMA1.
The moment I line up I switch it to Alt.

-Kees

[Thomas Borchert]

Orval,

> Most TXP antennae are belly-mounted. They send out a rather strong EM
> signal that can reflect off the pavement and overwhelm the receiver
> portion of the TXP, possibly damaging it.
>

I have never heard of that and find it implausible (unless possibly
taxiing on a bowl of concave sheet metal (PSP, anyone?)). Do you have
any examples of transponders actually damager by this?

--
Thomas Borchert (EDDH)

[Judah]

Newps > wrote in news:gKydnTb27tVqe7TeRVn-
:

>
> The change was made eons ago. There's no reason to turn the transponder
> to STBY anymore.

I had heard that while it doesn't interfere with ATC radar services, TCAS
systems don't filter it out, and you could be causing distractions for
other planes on approach if you leave your transponder on all the time.

[Bob Noel]

In article >,
Judah > wrote:

> I had heard that while it doesn't interfere with ATC radar services, TCAS
> systems don't filter it out, and you could be causing distractions for
> other planes on approach if you leave your transponder on all the time.

what TCAS II system gives RA below 1000' agl?

--
Bob Noel
no one likes an educated mule

[Newps]

Judah wrote:

> Newps > wrote in news:gKydnTb27tVqe7TeRVn-
> :
>
>
>>The change was made eons ago. There's no reason to turn the transponder
>>to STBY anymore.
>
>
> I had heard that while it doesn't interfere with ATC radar services, TCAS
> systems don't filter it out, and you could be causing distractions for
> other planes on approach if you leave your transponder on all the time.

You heard wrong.

[[email protected]]

My avionics guy told me that the encoder (older ones, at least) have
a heater in them to stabilize altitude readings, and that the standby
function warms up the heater and the cavity tube in the transponder
that generates the return signal. The transponder won't go to work
until it's ready.
The transponder puts out a very brief 400-watt signal, at radar
freqencies, and I could see this being reflected off pavement and
entering the receiver directly (not through the antenna) except that
the box is aluminum and should constitute good shielding. I haven't
heard of any transponders being damaged this way, but then I've had
quite a few of them fixed over the years without knowing why they
failed. Maybe that signal damages navcoms instead.

Dan

[Andrew Gideon]

Andrew Sarangan wrote:

> In fact I would recommend to turn the transponder on before even getting
> on the runway.

Same here. I'll run through the "lights, camera, action" checklist as I
start the taxi roll over the hold short line. I've never had to wait more
than a minute or so between a "position and hold" and "takeoff", so it's
never been a problem. The only "non-flying" thing I do when starting the
actual t/o roll is to start the timer, and I do that before the throttle.

I don't want my hand to be near the transponder or strobe switch when I
decide to abort a t/o.

- Andrew

[Maule Driver]

Jay Honeck wrote:
>>I make no attempt to turn it off or go to standby while taxiing or
>>anything else. I've never been asked to go to standby or otherwise
>>questioned.
>
> Standby gets used only:
> a) At OSH, per the NOTAM.
> and
> b) When flying as a flight of two.
>
> Otherwise, it may as well be soldered "on"...

That's what I'm saying!

[Garner Miller]

In article >, Maule Driver
> wrote:

> I don't.

You should.

From the AIM:

4-1-19. Transponder Operation
a. General
3. Civil and military transponders should be adjusted to the "on" or
normal operating position as late as practicable prior to takeoff and
to "off" or "standby" as soon as practicable after completing landing
roll, unless the change to "standby" has been accomplished previously
at the request of ATC.

--
Garner R. Miller
ATP/CFII/MEI
Clifton Park, NY =USA=

[Bob Fry]

Yes, when flying in formation with others and I'm not lead. Lead
squawks, the others use standby.

[Greg Copeland]

On Thu, 15 Sep 2005 23:00:10 +0000, Jay Masino wrote:

> Orval Fairbairn > wrote:
>> Most TXP antennae are belly-mounted. They send out a rather strong EM
>> signal that can reflect off the pavement and overwhelm the receiver
>> portion of the TXP, possibly damaging it.
>
> I would be surprised if most modern transponders don't protect against
> this themselves by blanking the receiver during the transmit.
>
> --- Jay

I would be surprised if the reflected power comes close to the power
received from radar...especially when near field with radar on field. Of
course, any additional information you can provide on this, I would be
most interested in reading! :)

Greg

[Jay Masino]

Greg Copeland > wrote:
> I would be surprised if the reflected power comes close to the power
> received from radar...especially when near field with radar on field.

That too.


--
__!__
Jay and Teresa Masino ___(_)___
http://www2.ari.net/jmasino ! ! !
http://www.OceanCityAirport.com
http://www.oc-Adolfos.com

[Tauno Voipio]

Orval Fairbairn wrote:
> In article >,
> Thomas Borchert > wrote:
>
>
>>Orval,
>>
>>
>>>I set to "Standby" on the ground, to prevent reflections that could
>>>damage the unit.
>>>
>>
>>Say again? Or rather, explain that, please.
>
>
> Most TXP antennae are belly-mounted. They send out a rather strong EM
> signal that can reflect off the pavement and overwhelm the receiver
> portion of the TXP, possibly damaging it.


1. The signal (about 200 W) is already on the feed line
even without a reflection.

2. The vertical antenna has a radiation minimum straight down.

3. The receiver is 60 MHz off the transmit frequency
(1030 and 1090 MHz).

4. The receiver is blanked and switched off the feedline
during the transmit pulses.

5. There is often an interlock line between the DME and
transponder to protect both receivers during pulse
transmit from either unit.

--

Tauno Voipio
tauno voipio (at) iki fi

[Judah]

Bob Noel > wrote in
:

> In article >,
> Judah > wrote:
>
>> I had heard that while it doesn't interfere with ATC radar services,
>> TCAS systems don't filter it out, and you could be causing
>> distractions for other planes on approach if you leave your
>> transponder on all the time.
>
> what TCAS II system gives RA below 1000' agl?
>

I don't know. It was something I heard, not something I experienced.

Besides, if there is a TCAS II, perhaps there is also a TCAS I which isn't
as well protected as a TCAS II...

:)

[Judah]

Newps > wrote in
:

> You heard wrong.

Funny, this aviation business.

It seems that about 50% of the stuff you hear from people who are supposed
to know more than you - instructors, experienced pilots, etc., etc. - is
urban legend, stated as if it were plain fact.

Sometimes it's hard to figure out what's real and what's bulls&^*
especially when the bulls^&* sounds so real...

(eg: if there is no valid use for a SBY mode, why is it there?)

[cjcampbell]

Maule Driver wrote:
> I don't. It stays on 24/7 (you know what I mean). 1200 unless given a
> code. It effectively prevents "Maule, check your transponder" unless
> using the wrong code.

Not a terrible idea. If the tower doesn't like it they can say so.

Personally, I turn it on at engine runup -- never on the runway. If I
forgot to turn it on, I don't think reaching over and switching it
would be a distraction. But then, I fly enough that I don't have to
look or even think about the transponder switch.

Some transponders have a 'ground' mode. The Garmin G-1000 turns its
transponder on and off automatically.

[Roger]

On Thu, 15 Sep 2005 17:15:14 GMT, Maule Driver
> wrote:

>I don't. It stays on 24/7 (you know what I mean). 1200 unless given a
>code. It effectively prevents "Maule, check your transponder" unless
>using the wrong code.
>
I was taught to use standby when on the ground and it says to do so
right in the manual.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
>I make no attempt to turn it off or go to standby while taxiing or
>anything else. I've never been asked to go to standby or otherwise
>questioned.
>
>This has been discussed before but I'd suggest the everyone can do this
>without causing a problem for anyone.

[Newps]

Judah wrote:

> Newps > wrote in
> :
>
>
>>You heard wrong.
>
>
> Funny, this aviation business.
>
> It seems that about 50% of the stuff you hear from people who are supposed
> to know more than you - instructors, experienced pilots, etc., etc. - is
> urban legend, stated as if it were plain fact.



It used to be right, but times and technology change and those reasons
are no longer valid.

[Lakeview Bill]

From the 2005 AIM...

4-1-19. TRANSPONDER OPERATION

a. General:

3. Civil and military transponders should be adjusted to the "on" or normal
operating position as late as practicable prior to takeoff and to "off" or
"standby" as soon as practicable after completing landing roll, unless the
change to "standby" has been accomplished previously at the request of ATC.

d. Transponder IDENT Feature:

1. The transponder shall be operated only as specified by ATC. Activate the
"IDENT" feature only upon request of the ATC controller.



"Newps" > wrote in message
...
>
>
> Judah wrote:
>
> > Newps > wrote in
> > :
> >
> >
> >>You heard wrong.
> >
> >
> > Funny, this aviation business.
> >
> > It seems that about 50% of the stuff you hear from people who are
supposed
> > to know more than you - instructors, experienced pilots, etc., etc. - is
> > urban legend, stated as if it were plain fact.
>
>
>
> It used to be right, but times and technology change and those reasons
> are no longer valid.

[Greg Farris]

"Standby" used to be a common function on vacuum tube equipment, keeping the
filaments hot, but cutting the plate current, so the device could be turned
"ON" and operate instantly, without having to wait for the filaments to heat
up and start emmitting. Some solid state equipment retained this function,
just because people were used to it, and operators had been taught to use it.


Is it possible that this is the case with the transponder? Anyone know of a
tube transponder?

I always learned that you are to use only two modes on the transponder -
"Standby" and "ALT" (or mode "C"). ON and OFF were never to be selected.

I was also instructed to IDENT after acknowledging a transponder code change,
even if not specifically requested to do so by ATC. The reasoning was that
they will see your ident immediately, while it may take them up to a minute
to see your code change.

G Faris

[TaxSrv]

"Greg Farris" wrote"
> "Standby" used to be a common function on vacuum tube
> equipment, keeping the filaments hot, but cutting the plate
> current, so the device could be turned "ON" and operate
> instantly, without having to wait for the filaments to heat up
> and start emmitting. Some solid state equipment retained
> this function, just because people were used to it, and
> operators had been taught to use it.
> ...

They all must have that function, as it's in the TSO! I'm sure it
was at the behest of ATC back when written, not for circuit design
considerations. Latter ain't FAA's problem, but the
manufacturers'.

>
> Is it possible that this is the case with the transponder? Anyone
> know of a tube transponder?

ebay.com now and then. Shipping will far exceed winning bid
price.

Fred F.

[Thomas Borchert]

Greg,

> I was also instructed to IDENT after acknowledging a transponder code change,
> even if not specifically requested to do so by ATC.
>

Alas, and it would have been so easy for your instructor (and all the others out
there) to read the AIM.

--
Thomas Borchert (EDDH)

[Thomas Borchert]

Judah,

> It seems that about 50% of the stuff you hear from people who are supposed
> to know more than you - instructors, experienced pilots, etc., etc. - is
> urban legend, stated as if it were plain fact.
>

Hey, and this is the easy stuff - transponder operation is covered in the
AIM, which, for all practical purpose, has quasi-regulatory character (I
know, another discussion just waiting to happen).

Then, there's the less obvious (to some) stuff, like downwind turns, running
lean-of-peak or aging of composites.

--
Thomas Borchert (EDDH)

[Steven P. McNicoll]

"Greg Farris" > wrote in message
...
>
> I was also instructed to IDENT after acknowledging a transponder code
> change,
> even if not specifically requested to do so by ATC. The reasoning was that
> they will see your ident immediately, while it may take them up to a
> minute
> to see your code change.
>

Did your instructor say why that was the case? Did he believe the radar
antenna rotated faster when the IDENT button was activated?

[Ron Natalie]

Greg Farris wrote:

> Is it possible that this is the case with the transponder? Anyone know of a
> tube transponder?

Yeah, KT76 and lots of others. Microwave tubes are still in use.
Actually the biggest thing you want to use STANDBY for is many encoders
need preheat on their pressure sensing element.
>
> I always learned that you are to use only two modes on the transponder -
> "Standby" and "ALT" (or mode "C"). ON and OFF were never to be selected.

Fine if you have a avionics master, but I'd tell you to shut your
transponder off while cranking the engine. Further ON (or Mode A)
is required when ATC asks you to stop altitude squawk (has happened
to me).

>
> I was also instructed to IDENT after acknowledging a transponder code change,
> even if not specifically requested to do so by ATC. The reasoning was that
> they will see your ident immediately, while it may take them up to a minute
> to see your code change.
>
Not only is this the wrong procedure, it's bull****. The IDENT and the
code
are transmitted with the same frequency.
>

[Ron Natalie]

cjcampbell wrote:

> Some transponders have a 'ground' mode. The Garmin G-1000 turns its
> transponder on and off automatically.
>

The Garmin transponders automatically turn on and off (my GTX33 does)
based I suppose on noticing that the encoded altitude has jumped since
it was turned on.

The the SL70 (formerly Apollo) transponder also has an engage mode if
an attached device (like your GPS) says it is now moving at a certain
threshold speed.