[balloon-makers] Code Orange and ADIZ

David Tanzer davidandlori at greenmountainaccess.net
Wed Mar 19 09:02:22 CST 2003

I used to own an airplane (okay, I was an idiot and I sold it), so I
have some experience with transponders and altitude encoders.
Transponders generally do not have built in altitude encoders.  Several
companies sell encoders that will work with virtually any
transponder--they use a common interface.  Encoders are generally not
very expensive.  The only alternative is to purchase an encoding
altimeter, which looks like a regular aircraft altimeter but has
electronics built into it to provide a transponder with electronic
attitude data in much the same way that an altitude encoder does.  These
are quite costly, and wouldn't make sense to have in a balloon.  BTW,
when you select the "Mode-C" setting on a transponder, you are telling
it to transmit the data it obtains from an altitude encoder to ATC.
That altitude is rounded to the nearest 100 feet, and then transmitted
along with the Squawk code you have entered into your transponder.

http://www.gulf-coast-avionics.com lists two altitude encoders: an
Ameri-King AK-350 for $154 and Sandia Aerospace SAE5-35 for $359.  Used
and reconditioned transponders are also readily available for relatively
modest sums.  For instance, the venerable King KT-76A can easily be
found for $750, and they are virtually bullet proof.  If you are going
to do this, I wouldn't get too fancy.  Do you really need to spend
$2,000 for an ICOM transponder that has an LED display and a VFR button
(that lets you select 1200 with a single button push)?  Or will a simple
King where you have to twist four separate knobs do for $1,250 less?
It's one thing if you're doing serious IFR flying in an airplane and
something like the ICOM reduces workload significantly, but that's not a
problem in a balloon.  

As well, before I went to the trouble and considerable expense of
assembling this equipment, I would call New York TRACON to make sure
they will approve a balloon's request to operate in the New York ADIZ.
They are not obligated to do so.  You might call New York approach on
the appropriate frequency thinking you are all set because you have a
transponder with altitude encoder, but they might simply say "Balloon
1234 remain clear of the New York ADIZ."
Also, you should be aware that you must have a licensed avionics shop
complete a transponder and altitude encoder check every 24 months or it
is not legal for you to turn your transponder on.  The FAA will also
likely require the filing of a 337 to fly with a transponder in your
balloon.  You should check with your local FSDO to find out.

Finally, somehow the thought of monitoring New York Approach on your VHF
radio with all their attendant chatter, which you will be required to do
once you call them to obtain a Squawk (if they'll give you one), doesn't
seem to fit with the image of a peaceful balloon flight.  To each his
own, certainly, but I'd spend my money on that wonderful fabric I've
been eyeing for my next project.

David Tanzer
Charlotte, VT

-----Original Message-----
From: private e-mail address
[mailto:private e-mail address] On Behalf Of Keith Sproul
Sent: Wednesday, March 19, 2003 9:22 AM
To: private e-mail address
Subject: RE: [balloon-makers] Code Orange and ADIZ

I am looking to put something similar together.  The GTX320 looks 
nice (it is Garmin), but as far as I can tell, it isn't made any more.

Also, do any of these have the altimeter built in? or what kind of 
altimeter to you need to use with them??

There are several up on Ebay, but I don't know enough about them to 
even know what to look at..

Keith Sproul

At 18:45 -0500 3/18/03, private e-mail address wrote:
>Now for the question, does anyone have any experince with portable
>transponders??  anyone know where to buy one (cheap)?
>Yeah, fly with one everytime. Icom have a small solid state one GTX320
>think its called. We put ours in a plastic tool box with large
>battery and strap it on the outside of the basket. The antenna is on a
>plate on the burner frame although its better to have it underneath
that can
>become expensive in antennas.
>If you have not used a transponder before get an aeroplane driver to
show you
>how. I used to work at a radar unit and you can't believe the trouble
>operating transponders incorrectly can cause.

Keith Sproul	private e-mail address		WU2Z
Student Housing Network Coordinator		732 445-3695 W
Rutgers University Computing Services

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