"A Guide to Transponders in Sailplanes" - updated!

[Eric Greenwell[_2_]]

This guide, originally published in Soaring in 2002, and updated in
2004, is now expanded another 10 pages to include information on Mode
S transponders, ADS-B equipment, portable transponder detectors like
the Zaon MRX, and the "glider TCAS" (FLARM).

Other new sections are "Myth-information about transponders" and "Why
doesn't the SSA..." Even if you have a transponder already, you might
enjoy reading those two sections.

The updated Guide is available from the Soaring Safety Foundation
website at:

http://tinyurl.com/y739x4

or you can go to the site and find it yourself:

http://www.soaringsafety.org/

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

[kirk.stant]

Eric,

Excellent document - should be required reading for all glider (and
power) pilots.

One comment - you state that a transponder will not provide protection
from "tactical aircraft like fighters that don't use TCAS". While it
is true that fighters don't have TCAS, most Air Force fighters
(specifically, all F-15s and most F-16s) have active transponder
interrogators (in addition to their air-to-air radar) that can detect
transponder equipped gliders very easily. Even the old F-4 that I
used to fly in had a crude but effective transponder interrogator, and
we used it a lot to find VFR traffic when low flying in MOAs (the
antique steam-powered radar in the F-4 left a lot to be desired at low
altitude...)

The A-10, as far as I know, isn't equipped with either air-to-air
radar or an interrogator - so if you share aispace with Warthogs. keep
an eye out for them!

As far as Navy/Marine fighters - all F-18s have air-to-air radars, but
I think only the latest Hornets have an interrogator. Not sure about
Harriers, but again, the later Harriers have basically the same air-to-
air radar as the Hornet.

Transponders are wonderful, but I really think a detector device like
the MRX is even more essential in some areas.

Cheers,

Kirk
66

[BB]

Very nice update. One missing issue: installation legalities. I konw
some pilots have gotten 337s. I know that many have not. Do we really
need a 337? What reg says so (I looked to no avail)? Why, for example,
would a transponder need a 337 but a radio does not? What is, really,
required to legally install a transponder?

John Cochrane

[Eric Greenwell[_2_]]

On Feb 11, 12:47 am, "kirk.stant" > wrote:
> Eric,
>
> Excellent document - should be required reading for all glider (and
> power) pilots.
>
> One comment - you state that a transponder will not provide protection
> from "tactical aircraft like fighters that don't use TCAS". While it
> is true that fighters don't have TCAS, most Air Force fighters
> (specifically, all F-15s and most F-16s) have active transponder
> interrogators (in addition to their air-to-air radar) that can detect
> transponder equipped gliders very easily. Even the old F-4 that I
> used to fly in had a crude but effective transponder interrogator, and
> we used it a lot to find VFR traffic when low flying in MOAs (the
> antique steam-powered radar in the F-4 left a lot to be desired at low
> altitude...)
>
> The A-10, as far as I know, isn't equipped with either air-to-air
> radar or an interrogator - so if you share aispace with Warthogs. keep
> an eye out for them!
>
> As far as Navy/Marine fighters - all F-18s have air-to-air radars, but
> I think only the latest Hornets have an interrogator. Not sure about
> Harriers, but again, the later Harriers have basically the same air-to-
> air radar as the Hornet.
>
> Transponders are wonderful, but I really think a detector device like
> the MRX is even more essential in some areas.
>
> Cheers,
>
> Kirk
> 66

THanks, Kirk, I'll look into these and update as needed. We're on the
road to the convention at the moment.

Eric

[Eric Greenwell[_2_]]

On Feb 11, 11:00 am, BB > wrote:
> Very nice update. One missing issue: installation legalities. I konw
> some pilots have gotten 337s. I know that many have not. Do we really
> need a 337? What reg says so (I looked to no avail)? Why, for example,
> would a transponder need a 337 but a radio does not? What is, really,
> required to legally install a transponder?
>
> John Cochrane

I've skirted around the legalities, because it's a confusing issue to
me, too. I would like to address it, however, so if someone
knowledgeable can provide me with info on it, or point to a good
source (documents or person(s)), I'll be glad to add a section on it.

Otherwise, we'll have to wait until I can dig it out myself!

[User]

You say to mount the aerial under your thigh.... not a good idea for a
200 watt transmitter cause it will cook your balls. Most Transponders
have a minimum distance allowed from people, like 3 feet. Please check
this out !

Eric Greenwell wrote:
> On Feb 11, 11:00 am, BB > wrote:
>> Very nice update. One missing issue: installation legalities. I konw
>> some pilots have gotten 337s. I know that many have not. Do we really
>> need a 337? What reg says so (I looked to no avail)? Why, for example,
>> would a transponder need a 337 but a radio does not? What is, really,
>> required to legally install a transponder?
>>
>> John Cochrane
>
> I've skirted around the legalities, because it's a confusing issue to
> me, too. I would like to address it, however, so if someone
> knowledgeable can provide me with info on it, or point to a good
> source (documents or person(s)), I'll be glad to add a section on it.
>
> Otherwise, we'll have to wait until I can dig it out myself!

[Tim Mara]

absolutely....installing a transponder doesn't require any documentation if
it's in a experimental other than maybe a logbook entry and a new
wt/bal......BUT turning it on does!
Any Transponder equipped aircraft has to have a static system test and be
signed off by an approved avionics repair station prior to use....these all
then can be monitored by ATC... without this what is to prevent a
transponder equipped glider flying at 10,000' and reporting to ATC that he
is actually at 9000' and directly in line with the flight path of a 747!
Also.....consider, a Transponder equipped aircraft is also REQUIRED to have
the transponder ON and reporting at all times from wheels up to wheels
down......not just as I have heard many glider pilots saying they "only use"
the transponder when they are flying at or near areas of high traffic....
think about this....
tim

Please visit the Wings & Wheels website at www.wingsandwheels.com
>
> Eric Greenwell wrote:
>> On Feb 11, 11:00 am, BB > wrote:
>>> Very nice update. One missing issue: installation legalities. I konw
>>> some pilots have gotten 337s. I know that many have not. Do we really
>>> need a 337? What reg says so (I looked to no avail)? Why, for example,
>>> would a transponder need a 337 but a radio does not? What is, really,
>>> required to legally install a transponder?
>>>
>>> John Cochrane
>>
>> I've skirted around the legalities, because it's a confusing issue to
>> me, too. I would like to address it, however, so if someone
>> knowledgeable can provide me with info on it, or point to a good
>> source (documents or person(s)), I'll be glad to add a section on it.
>>
>> Otherwise, we'll have to wait until I can dig it out myself!

[Eric Greenwell[_2_]]

On Feb 14, 2:12 am, user > wrote:
> You say to mount the aerial under your thigh.... not a good idea for a
> 200 watt transmitter cause it will cook your balls. Most Transponders
> have a minimum distance allowed from people, like 3 feet. Please check
> this out !

I mentioned some pilots have mounted it in that position. I don't
think I said to do it that way. Can you tell me the page and paragraph
that leads you to think I recommended it? Perhaps its not written
clearly.

And to reiterate, it's not a "200 watt transmitter". The peak power of
the pulses is 200 watt, but it's only about a 5 watt max transmitter,
as the pulses are short.

[Eric Greenwell[_2_]]

On Feb 14, 7:44 am, "Tim Mara" > wrote:
> absolutely....installing a transponder doesn't require any documentation if
> it's in a experimental other than maybe a logbook entry and a new
> wt/bal......BUT turning it on does!
> Any Transponder equipped aircraft has to have a static system test and be
> signed off by an approved avionics repair station prior to use....these all
> then can be monitored by ATC... without this what is to prevent a
> transponder equipped glider flying at 10,000' and reporting to ATC that he
> is actually at 9000' and directly in line with the flight path of a 747!

Even worse would be the glider reporting it was at 9000' and have the
747 at 10,000'. ATC deals with this by acknowledging the VFR target
might not be reporting until they've had contact with the pilot and
verified the altitude.

> Also.....consider, a Transponder equipped aircraft is also REQUIRED to have
> the transponder ON and reporting at all times from wheels up to wheels
> down......not just as I have heard many glider pilots saying they "only use"
> the transponder when they are flying at or near areas of high traffic....
> think about this....

A lot of us have thought about this, including people in the FAA, and
decided it's a lot better to have a transponder on in areas that need
it, instead of risking a dead battery (meaning NO radio or
transponder) later in the flight, or discouraging pilots with marginal
batteries from installing a transponder. I covered this in the the
"Guide". Take a look at that section and see if it promotes flight
safety better than strict adherence to the "always on" rule; also,
take a look at the "Why doesn't the SSA ..." section that addresses
the FAA's official position.

[Mike the Strike]

> > Also.....consider, a Transponder equipped aircraft is also REQUIRED to have
> > the transponder ON and reporting at all times from wheels up to wheels
> > down......not just as I have heard many glider pilots saying they "only use"
> > the transponder when they are flying at or near areas of high traffic....
> > think about this....
>
> A lot of us have thought about this, including people in the FAA, and
> decided it's a lot better to have a transponder on in areas that need
> it, instead of risking a dead battery (meaning NO radio or
> transponder) later in the flight, or discouraging pilots with marginal
> batteries from installing a transponder. I covered this in the the
> "Guide". Take a look at that section and see if it promotes flight
> safety better than strict adherence to the "always on" rule; also,
> take a look at the "Why doesn't the SSA ..." section that addresses
> the FAA's official position.

This argument seems rather like deciding to put your seat belt on in a
car just before you have a crash!

Anyway, this rule isn't an option, it is mandatory. If you have a
transponder the regs say it MUST be on while you are flying. No pilot
discretion here.

And don't give me the battery argument. Electricity is the fuel for
your instruments, including your safety ones such as the radio and
transponder. In my book, starting a flight with insufficient battery
power is as irresponsible as flying a power plane cross-country with
insufficient fuel.

It's the pilot's responsibility to make sure that he has everything
needed for a safe flight and to comply with regulations and that
includes power for the instruments.

Mike

[Mike the Strike]

On Feb 14, 9:42 pm, Mike the Strike > wrote:
> > > Also.....consider, a Transponder equipped aircraft is also REQUIRED to have
> > > the transponder ON and reporting at all times from wheels up to wheels
> > > down......not just as I have heard many glider pilots saying they "only use"
> > > the transponder when they are flying at or near areas of high traffic....
> > > think about this....
>
> > A lot of us have thought about this, including people in the FAA, and
> > decided it's a lot better to have a transponder on in areas that need
> > it, instead of risking a dead battery (meaning NO radio or
> > transponder) later in the flight, or discouraging pilots with marginal
> > batteries from installing a transponder. I covered this in the the
> > "Guide". Take a look at that section and see if it promotes flight
> > safety better than strict adherence to the "always on" rule; also,
> > take a look at the "Why doesn't the SSA ..." section that addresses
> > the FAA's official position.
>
> This argument seems rather like deciding to put your seat belt on in a
> car just before you have a crash!
>
> Anyway, this rule isn't an option, it is mandatory. If you have a
> transponder the regs say it MUST be on while you are flying. No pilot
> discretion here.
>
> And don't give me the battery argument. Electricity is the fuel for
> your instruments, including your safety ones such as the radio and
> transponder. In my book, starting a flight with insufficient battery
> power is as irresponsible as flying a power plane cross-country with
> insufficient fuel.
>
> It's the pilot's responsibility to make sure that he has everything
> needed for a safe flight and to comply with regulations and that
> includes power for the instruments.
>
> Mike

I should add that the article is excellent - the battery issue and
turning transponders off is the only point that I disagree with. With
a $2,000+ transponder in a $50,000+ sailplane, it seems ironic that
people are too mean to add another $10 battery. A dedicated 7 Ah
battery will power a Microair transponder for 12 to 15 hours, in my
experience. This is a no-brainer.

We have had a collision between an aircraft and a sailplane whose
transponder was turned off "to save the batteries", so this isn't just
a theoretical problem.

Mike

[bumper]

"Eric Greenwell" > wrote in message
...
>
> And to reiterate, it's not a "200 watt transmitter". The peak power of
> the pulses is 200 watt, but it's only about a 5 watt max transmitter,
> as the pulses are short.


I know you are talking about peak power vs average power. However, even
though pulse width is narrow, and thus the average radiation from a 175 or
250 watt transponder might be on the order of 5 watts, I'm not sure the
radiation exposure should be equated to just the low average power.

Consider a single high powered pulse as being one .22 rifle bullet. The
bullet might have on the order of 100 ft pounds of energy and would
obviously do considerable tissue damage. Compare that to several hundred
BB's from a low powered air rifle, the combined energy of which equals the
energy of that one .22 bullet. Same total energy, far less damage. The point
I'm trying to make is that pulsed high energy may well do more tissue damage
than the same total amount of low level energy delivered over a longer time
frame.

I want that transponder antenna installed away from me.

bumper

[Mike the Strike]

On Feb 15, 10:18 am, "bumper" > wrote:
> "Eric Greenwell" > wrote in message
>
> ...
>
>
>
> > And to reiterate, it's not a "200 watt transmitter". The peak power of
> > the pulses is 200 watt, but it's only about a 5 watt max transmitter,
> > as the pulses are short.
>
> I know you are talking about peak power vs average power. However, even
> though pulse width is narrow, and thus the average radiation from a 175 or
> 250 watt transponder might be on the order of 5 watts, I'm not sure the
> radiation exposure should be equated to just the low average power.
>
> Consider a single high powered pulse as being one .22 rifle bullet. The
> bullet might have on the order of 100 ft pounds of energy and would
> obviously do considerable tissue damage. Compare that to several hundred
> BB's from a low powered air rifle, the combined energy of which equals the
> energy of that one .22 bullet. Same total energy, far less damage. The point
> I'm trying to make is that pulsed high energy may well do more tissue damage
> than the same total amount of low level energy delivered over a longer time
> frame.
>
> I want that transponder antenna installed away from me.
>
> bumper

A colleague who deals with radiation safety said that the argument
that low energy long-duration doses of radiation are equivalent to
high energy short duration doses is like equating jumping off a 3-foot
wall ten times with jumping off a 30-foot wall once.

Mike

[Andy[_1_]]

On Feb 14, 9:59*pm, Mike the Strike > wrote:
> On Feb 14, 9:42 pm, Mike the Strike > wrote:
> We have had a collision between an aircraft and a sailplane whose
> transponder was turned off "to save the batteries", so this isn't just
> a theoretical problem.

The report I read said the transponder was not turned on because the
transponder installation was not certified. Did you hear different?

It is illegal to operate a transponder without current certification.

Andy

[Ian[_2_]]

I found this an interesting article, and largely ties in with my personal
experiences with transponders. However I have two comments:

On Thu, 14 Feb 2008 10:44:57 -0500, Tim Mara wrote:

> Any Transponder equipped aircraft has to have a static system test and
> be signed off by an approved avionics repair station prior to
> use....these all then can be monitored by ATC... without this what is to
> prevent a transponder equipped glider flying at 10,000' and reporting to
> ATC that he is actually at 9000' and directly in line with the flight
> path of a 747!

Firstly, Regulations aside. I am not sure that the error of cockpit
static verses static from the static ports makes a significant difference
in altitude readings in a typical glider. All of our Flight Recorders and
Barographs read cockpit static and I have never heard of a trace that had
obvious errors (eg trace 500' into controlled due to static errors, or a
significant deviation between GPS altitude and baragraph altitude that
could not be explained by the atmospheric conditions on the day.) Now a
power aircraft with a pressurized cabin presents a different challenge ...

Secondly, the problem with batteries is that there is no practical way to
"certify" the amount of energy available in the battery before the
flight. It can be estimated from the state of charge and the known age/
condition, but it can't be measured like the fuel level in a tank. Worse
still, when a battery fails during flight its performance degrades
gradually so may not be immediately apparent to the pilot that there is a
problem. In this situation the transponder display might look healthy
while ATC get an inaccurate signal, a weak one or none at all. (I have
seen my encoder read 400' out when running of a deteriorating battery.)

For this reason I believe it is essential to have at least two 7Ah
batteries, as well as a means to switch between them so they can be used
as a "main" battery to a "standby" one. At least when you switch over you
know the first battery is depleted, if it happens prematurely then you
know it needs to be replaced.

Ian

[Mike the Strike]

On Feb 15, 1:56 pm, Andy > wrote:
> On Feb 14, 9:59 pm, Mike the Strike > wrote:
>
> > On Feb 14, 9:42 pm, Mike the Strike > wrote:
> > We have had a collision between an aircraft and a sailplane whose
> > transponder was turned off "to save the batteries", so this isn't just
> > a theoretical problem.
>
> The report I read said the transponder was not turned on because the
> transponder installation was not certified. Did you hear different?
>
> It is illegal to operate a transponder without current certification.
>
> Andy

The report I read said the operator was not familiar with the
instruments and was concerned about battery drain. I don't know if
someone operating a ship not their own would even worry about
certification.

Mike

[Eric Greenwell[_2_]]

On Feb 15, 12:08 pm, Mike the Strike > wrote:

>
> A colleague who deals with radiation safety said that the argument
> that low energy long-duration doses of radiation are equivalent to
> high energy short duration doses is like equating jumping off a 3-foot
> wall ten times with jumping off a 30-foot wall once.

It's my understanding that microwave radiation at these power levels
and the mass of tissue involved will primarily cause heating by
vibrating water molecules, and no significant ionization. The amount
of heating produced depends on the amount of energy delivered and the
amount of mass. So, 5 watts is the important number in this case, and
most of that will not be delivered to the body, but will be radiated
in directions away from the body.

I hope it's clear that I don't recommend putting the antenna close to
your body; however, it but that pilots have done it and have
apparently suffered no ill effects. Unfortunately, I don't know of any
documents addressing this question directly.

[Eric Greenwell[_2_]]

On Feb 14, 8:42 pm, Mike the Strike > wrote:
> > > Also.....consider, a Transponder equipped aircraft is also REQUIRED to have
> > > the transponder ON and reporting at all times from wheels up to wheels
> > > down......not just as I have heard many glider pilots saying they "only use"
> > > the transponder when they are flying at or near areas of high traffic....
> > > think about this....
>
> > A lot of us have thought about this, including people in the FAA, and
> > decided it's a lot better to have a transponder on in areas that need
> > it, instead of risking a dead battery (meaning NO radio or
> > transponder) later in the flight, or discouraging pilots with marginal
> > batteries from installing a transponder. I covered this in the the
> > "Guide". Take a look at that section and see if it promotes flight
> > safety better than strict adherence to the "always on" rule; also,
> > take a look at the "Why doesn't the SSA ..." section that addresses
> > the FAA's official position.
>
> This argument seems rather like deciding to put your seat belt on in a
> car just before you have a crash!

And that is the only time you need to have it on - it has no value at
any other time.

Actually, the argument is more about encouraging people to install the
seat belt in the first place, and hope they will use it when it
matters.
>
> Anyway, this rule isn't an option, it is mandatory. If you have a
> transponder the regs say it MUST be on while you are flying. No pilot
> discretion here.

The nuance here is that we are not required to have transponders
installed, so it seems reasonable to argue that pilot A, who turns on
the transponder for some of the flight, is improving safety more than
pilot B, who doesn't install a transponder. Yes, pilot A is operating
contrary to the regulations and pilot B isn't, but which one is making
flight safer? Our SSA representatives that discuss these things with
the FAA say the FAA much prefers pilot A.

[Eric Greenwell[_2_]]

On Feb 14, 8:59 pm, Mike the Strike > wrote:
> On Feb 14, 9:42 pm, Mike the Strike > wrote:
>
>
>
> > > > Also.....consider, a Transponder equipped aircraft is also REQUIRED to have
> > > > the transponder ON and reporting at all times from wheels up to wheels
> > > > down......not just as I have heard many glider pilots saying they "only use"
> > > > the transponder when they are flying at or near areas of high traffic....
> > > > think about this....
>
> > > A lot of us have thought about this, including people in the FAA, and
> > > decided it's a lot better to have a transponder on in areas that need
> > > it, instead of risking a dead battery (meaning NO radio or
> > > transponder) later in the flight, or discouraging pilots with marginal
> > > batteries from installing a transponder. I covered this in the the
> > > "Guide". Take a look at that section and see if it promotes flight
> > > safety better than strict adherence to the "always on" rule; also,
> > > take a look at the "Why doesn't the SSA ..." section that addresses
> > > the FAA's official position.
>
> > This argument seems rather like deciding to put your seat belt on in a
> > car just before you have a crash!
>
> > Anyway, this rule isn't an option, it is mandatory. If you have a
> > transponder the regs say it MUST be on while you are flying. No pilot
> > discretion here.
>
> > And don't give me the battery argument. Electricity is the fuel for
> > your instruments, including your safety ones such as the radio and
> > transponder. In my book, starting a flight with insufficient battery
> > power is as irresponsible as flying a power plane cross-country with
> > insufficient fuel.
>
> > It's the pilot's responsibility to make sure that he has everything
> > needed for a safe flight and to comply with regulations and that
> > includes power for the instruments.
>
> > Mike
>
> I should add that the article is excellent - the battery issue and
> turning transponders off is the only point that I disagree with. With
> a $2,000+ transponder in a $50,000+ sailplane, it seems ironic that
> people are too mean to add another $10 battery.

That's not what stops pilots - it's the $1000 battery that stops them.
Many gliders require and additional battery when a transponder is
installed, and doing this in certified glider can be expensive.
Experimental certificate gliders can usually get by more cheaply.

> A dedicated 7 Ah
> battery will power a Microair transponder for 12 to 15 hours, in my
> experience. This is a no-brainer.

That is the solution I recommend, but see the cost of implementing it
stops some pilots from adding another battery. A 7 AH battery won't
run a vario, radio, gps, AND a full-time transponder for very long.


> We have had a collision between an aircraft and a sailplane whose
> transponder was turned off "to save the batteries", so this isn't just
> a theoretical problem.

And we are all agreed that if that was actually the case, it was a
very foolish decision, because that is a prime area for using a
transponder. But answer this: if that glider had not had a
transponder, would the jet have hit it more gently? He was not
required to have one, after all.

[Jim White]

>That's not what stops pilots - it's the $1000 battery
>that stops them.


Change your two 7ah batteries for readily available
9ah batteries that fit in the same hole at about $25
each. Job done.

No certification / inspector etc needed

[Mike Schumann]

I find it difficult to believe that adding a battery would cost $1,000. I
would think that this could be included as part of the installation of the
transponder.

Mike Schumann

"Eric Greenwell" > wrote in message
...
> On Feb 14, 8:59 pm, Mike the Strike > wrote:
>> On Feb 14, 9:42 pm, Mike the Strike > wrote:
>>
>>
>>
>> > > > Also.....consider, a Transponder equipped aircraft is also REQUIRED
>> > > > to have
>> > > > the transponder ON and reporting at all times from wheels up to
>> > > > wheels
>> > > > down......not just as I have heard many glider pilots saying they
>> > > > "only use"
>> > > > the transponder when they are flying at or near areas of high
>> > > > traffic....
>> > > > think about this....
>>
>> > > A lot of us have thought about this, including people in the FAA, and
>> > > decided it's a lot better to have a transponder on in areas that need
>> > > it, instead of risking a dead battery (meaning NO radio or
>> > > transponder) later in the flight, or discouraging pilots with
>> > > marginal
>> > > batteries from installing a transponder. I covered this in the the
>> > > "Guide". Take a look at that section and see if it promotes flight
>> > > safety better than strict adherence to the "always on" rule; also,
>> > > take a look at the "Why doesn't the SSA ..." section that addresses
>> > > the FAA's official position.
>>
>> > This argument seems rather like deciding to put your seat belt on in a
>> > car just before you have a crash!
>>
>> > Anyway, this rule isn't an option, it is mandatory. If you have a
>> > transponder the regs say it MUST be on while you are flying. No pilot
>> > discretion here.
>>
>> > And don't give me the battery argument. Electricity is the fuel for
>> > your instruments, including your safety ones such as the radio and
>> > transponder. In my book, starting a flight with insufficient battery
>> > power is as irresponsible as flying a power plane cross-country with
>> > insufficient fuel.
>>
>> > It's the pilot's responsibility to make sure that he has everything
>> > needed for a safe flight and to comply with regulations and that
>> > includes power for the instruments.
>>
>> > Mike
>>
>> I should add that the article is excellent - the battery issue and
>> turning transponders off is the only point that I disagree with. With
>> a $2,000+ transponder in a $50,000+ sailplane, it seems ironic that
>> people are too mean to add another $10 battery.
>
> That's not what stops pilots - it's the $1000 battery that stops them.
> Many gliders require and additional battery when a transponder is
> installed, and doing this in certified glider can be expensive.
> Experimental certificate gliders can usually get by more cheaply.
>
>> A dedicated 7 Ah
>> battery will power a Microair transponder for 12 to 15 hours, in my
>> experience. This is a no-brainer.
>
> That is the solution I recommend, but see the cost of implementing it
> stops some pilots from adding another battery. A 7 AH battery won't
> run a vario, radio, gps, AND a full-time transponder for very long.
>
>
>> We have had a collision between an aircraft and a sailplane whose
>> transponder was turned off "to save the batteries", so this isn't just
>> a theoretical problem.
>
> And we are all agreed that if that was actually the case, it was a
> very foolish decision, because that is a prime area for using a
> transponder. But answer this: if that glider had not had a
> transponder, would the jet have hit it more gently? He was not
> required to have one, after all.
>
>



--
Posted via a free Usenet account from http://www.teranews.com

[Marc Ramsey[_2_]]

Mike Schumann wrote:
> I find it difficult to believe that adding a battery would cost $1,000. I
> would think that this could be included as part of the installation of the
> transponder.

FWIW, we had a great deal of trouble with battery failures using a Terra
TRT250D transponder (nearly twice the power consumption of a Becker,
which wasn't then available in the US) in our Duo with the standard
installation of two 7ah batteries. We would get about 3 to 4 hours out
of each, failing to switch at the proper time would result in a useless
battery after a few cycles. We wanted to switch to 12ah batteries, but
there is essentially no room in a Duo for anything that size in an
accessible spot, if we still wanted to continue to carry drinking water,
survival kits, and/or jackets (this isn't the only glider with this
problem). So, we had the local shop reshape the molded battery wells in
the floor to accommodate the larger batteries. This involved cutting
out the existing wells, molding new larger ones, glassing them back in,
and painting. When all was said and done, it cost well over $1000, but
it solved the problem...

Marc

[Herb]

Excellent update on your fine article, thanks Eric!
Have to disagree regarding your points on NiMH batteries, though.
I've now flown now for over 2 years with them (including a dedicated
transponder battery) and I love them. Weight is about 60% of sealed
lead-acid, same for volume. The big advantage I see is in being able
to quick-charge them with 2A in a couple of hours very safely with
cheap automatic chargers available for example from all-battery.com or
ebay. I fly with 2 batteries for instrumentation/radio, each 5AH and
one for the transponder that has 10AH. One of the smaller batteries
is in the tail. Having much less mass in the area behind the
headrest is another plus. Shop around and find that the prices are
affordable and pre-wired 12V packs are offered.
I have not found the higher discharge rate in storage to be a factor.

Herb, J7

[Eric Greenwell]

Marc Ramsey wrote:
> Mike Schumann wrote:
>> I find it difficult to believe that adding a battery would cost
>> $1,000. I would think that this could be included as part of the
>> installation of the transponder.

snip

> So, we had the local shop reshape the molded battery wells in
> the floor to accommodate the larger batteries. This involved cutting
> out the existing wells, molding new larger ones, glassing them back in,
> and painting. When all was said and done, it cost well over $1000, but
> it solved the problem...

OK, now I know of two instances.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

[Eric Greenwell]

On Feb 16, 9:42 pm, "Mike Schumann" >
wrote:
> I find it difficult to believe that adding a battery would cost
$1,000. I
> would think that this could be included as part of the installation
of the
> transponder.

I hope I didn't scare anyone off, as I've heard of only one instance and
it was a certified glider. But, it is the kind of thing a few pilots
worry about.

Pilots with "newer" gliders will have factory locations for at least two
batteries; "older" gliders generally weren't so well equipped, so there
may be some effort and expense involved in adding another battery.

I suspect a more common problem than insufficient space for adequate
batteries is the battery getting low during the flight. This can happen
because the flight is much longer than usual, the battery(s) weren't
charged completely before takeoff, there was a battery or wiring
failure, or other problem. This is the main situation I tried to address
with the comments about using the transponder in the areas of greatest
risk, and turning it off elsewhere.

The point I was trying to make is that pilots that have just spent
~$2300 for a transponder, encoder, cabling, and antenna, plus looking at
some more for the installation, aren't going to balk at buying a $10 (or
even a $100 battery!) to power it. It's generally a much bigger amount
for the complete installation (at typical technician hourly rates in the
$50-$70 range) that makes the complete package to expensive for some pilots.

My "Guide" offers some ideas for dealing with the power issue, besides
the obvious one of adding another battery.


--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

[Eric Greenwell]

Mike the Strike wrote:
> On Feb 15, 10:18 am, "bumper" > wrote:
>> "Eric Greenwell" > wrote in message
>>
>> ...
>>
>>
>>
>>> And to reiterate, it's not a "200 watt transmitter". The peak power of
>>> the pulses is 200 watt, but it's only about a 5 watt max transmitter,
>>> as the pulses are short.
>> I know you are talking about peak power vs average power. However, even
>> though pulse width is narrow, and thus the average radiation from a 175 or
>> 250 watt transponder might be on the order of 5 watts, I'm not sure the
>> radiation exposure should be equated to just the low average power.
>>
>> Consider a single high powered pulse as being one .22 rifle bullet. The
>> bullet might have on the order of 100 ft pounds of energy and would
>> obviously do considerable tissue damage. Compare that to several hundred
>> BB's from a low powered air rifle, the combined energy of which equals the
>> energy of that one .22 bullet. Same total energy, far less damage. The point
>> I'm trying to make is that pulsed high energy may well do more tissue damage
>> than the same total amount of low level energy delivered over a longer time
>> frame.
>>
>> I want that transponder antenna installed away from me.
>>
>> bumper
>
> A colleague who deals with radiation safety said that the argument
> that low energy long-duration doses of radiation are equivalent to
> high energy short duration doses is like equating jumping off a 3-foot
> wall ten times with jumping off a 30-foot wall once.

Please ask your colleague if his analogy applies to microwave radiation.
Where I worked, "radiation safety" generally meant "atomic radiation
safety", including ionizing radiation (a bit like the bullet in bumper's
analogy) and gamma radiation. These tend to interact with tissue much
differently than microwave (radio) radiation.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

[Eric Greenwell]

Herb wrote:
> Excellent update on your fine article, thanks Eric!
> Have to disagree regarding your points on NiMH batteries, though.
> I've now flown now for over 2 years with them (including a dedicated
> transponder battery) and I love them. Weight is about 60% of sealed
> lead-acid, same for volume. The big advantage I see is in being able
> to quick-charge them with 2A in a couple of hours very safely with
> cheap automatic chargers available for example from all-battery.com or
> ebay. I fly with 2 batteries for instrumentation/radio, each 5AH and
> one for the transponder that has 10AH. One of the smaller batteries
> is in the tail. Having much less mass in the area behind the
> headrest is another plus. Shop around and find that the prices are
> affordable and pre-wired 12V packs are offered.

Your Googling was more productive than mine! Please send links to the
batteries and chargers you use, and part numbers if you can. I'll review
them and rewrite that section as needed.

> I have not found the higher discharge rate in storage to be a factor.

And pilots who find it is a factor might be able to counter it with
solar panel on the trailer.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

[Herb]

On Feb 20, 9:35 pm, Eric Greenwell > wrote:
> Herb wrote:
> > Excellent update on your fine article, thanks Eric!
> > Have to disagree regarding your points on NiMH batteries, though.
> > I've now flown now for over 2 years with them (including a dedicated
> > transponder battery) and I love them. Weight is about 60% of sealed
> > lead-acid, same for volume. The big advantage I see is in being able
> > to quick-charge them with 2A in a couple of hours very safely with
> > cheap automatic chargers available for example from all-battery.com or
> > ebay. I fly with 2 batteries for instrumentation/radio, each 5AH and
> > one for the transponder that has 10AH. One of the smaller batteries
> > is in the tail. Having much less mass in the area behind the
> > headrest is another plus. Shop around and find that the prices are
> > affordable and pre-wired 12V packs are offered.
>
> Your Googling was more productive than mine! Please send links to the
> batteries and chargers you use, and part numbers if you can. I'll review
> them and rewrite that section as needed.
>
> > I have not found the higher discharge rate in storage to be a factor.
>
> And pilots who find it is a factor might be able to counter it with
> solar panel on the trailer.
>
> --
> Eric Greenwell - Washington State, USA
> * Change "netto" to "net" to email me directly
>
> * Updated! "Transponders in Sailplanes"http://tinyurl.com/y739x4
> * New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more
>
> * "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org

Eric,
Here is a link for the battery (10Ah):
http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=1344
The charger I use is on the same page.
I just ordered 10 individual NiMh batteries of 10Ah capacity on ebay
but will have to wire the pack up myself. The price was only $60 plus
$10 for shipping:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=330158063379&ssPageName=STRK:MEWN:IT&ih=014

Regards,
Herb

[J a c k]

Tim Mara wrote:


> ...a Transponder equipped aircraft is also REQUIRED to have
> the transponder ON and reporting at all times from wheels up to wheels
> down....


Yes, we keep bumping against this reg whenever the subject comes up.

What is the rationale behind such a requirement?

Whose interests does it serve to differentiate between uninstalled
transponders and unused transponders?

Is it just another example of bureaucratic passive/aggressive
bitchiness, or is there an actual Safety of Flight context that
thoughtful glider pilots can appreciate?



Jack

[Darryl Ramm]

On Feb 22, 9:17 am, J a c k > wrote:
> Tim Mara wrote:
> > ...a Transponder equipped aircraft is also REQUIRED to have
> > the transponder ON and reporting at all times from wheels up to wheels
> > down....
>
> Yes, we keep bumping against this reg whenever the subject comes up.
>
> What is the rationale behind such a requirement?
>
> Whose interests does it serve to differentiate between uninstalled
> transponders and unused transponders?
>
> Is it just another example of bureaucratic passive/aggressive
> bitchiness, or is there an actual Safety of Flight context that
> thoughtful glider pilots can appreciate?
>
> Jack

I suspect it is to prevent thinking like "I'll just turn this little
box off and bust whatever FAR I feel like cuz noboby can see me" (even
if ATC can see you as a primary on radar). Seems a perfectly fine
requirement for a powered aircraft and I'd be surprised if gliders
were front and center in any thinking about this requirement. As for
bitchiness, the FAA seems to be showing perfect restraint in not
enforcing the thing you seemed concerned about, and therefore helping
encourage use of transponders in sailplanes. Of course we can keep
whining about this and other requirements and maybe in a long shot end
up with removing a regulation that does not seem to be enforced or
maybe worse end up with more regulations, maybe mandatory Mode-C/ADS-B
for all flight...

For many people flying in high-traffic areas, and that's a lot more
than just around Reno, it is not outrageous to expect them to install
batteries (and/or possibly solar panels at significantly higher cost)
so they can operate transponders thought quite long flights. So there
is no need to turn off those transponders - and in those areas that
*is* a safety of flight issue.

Darryl

[J a c k]

Darryl Ramm wrote:


> I suspect it is to prevent thinking like "I'll just turn this little
> box off and bust whatever FAR I feel like cuz noboby can see me" (even
> if ATC can see you as a primary on radar).

And "turning the little box off" is more deleterious to safety, or
enforcement, than no installation at all?



> Seems a perfectly fine
> requirement for a powered aircraft and I'd be surprised if gliders
> were front and center in any thinking about this requirement.


Agreed. Gliders are not often a concern. So why restrict gliders?



> ...the FAA seems to be showing perfect restraint in not
> enforcing the thing you seemed concerned about, and therefore helping
> encourage use of transponders in sailplanes.


I'm sure there are several practical considerations involved, including
the difficulty of enforcement. But when an agency "chooses" to enforce
or not enforce a particular reg, alarm bells ought to go off everywhere.
I don't dispute there are mostly rational people in the FAA. My dealings
with them have always been satisfactory. The problem is the process,
which does not seem very rational. The production of incompletely
structured, yet overly complex, regulations is pervasive in aviation, as
elsewhere.



> For many people flying in high-traffic areas, and that's a lot more
> than just around Reno, it is not outrageous to expect them to install
> batteries (and/or possibly solar panels at significantly higher cost)
> so they can operate transponders thought quite long flights. So there
> is no need to turn off those transponders - and in those areas that
> *is* a safety of flight issue.


It is reasonable that a transponder installation will include adequate
power to insure required operation of the equipment, when the
requirement is based on traffic management. It is not reasonable to
require that the installation will support operation in circumstances
where traffic management by ATC is not an issue. Decisions regarding use
of the transponder in circumstances not involving traffic separation or
National Security concerns should be left to the operator.

Non-enforcement is a non-reason. That can change overnight. If a rule is
illogical, or realistically unenforceable, or counter-productive, then
it ought not be a rule.



Jack

[Eric Greenwell]

J a c k wrote:

>> Seems a perfectly fine
>> requirement for a powered aircraft and I'd be surprised if gliders
>> were front and center in any thinking about this requirement.
>
>
> Agreed. Gliders are not often a concern. So why restrict gliders?

Here's an excerpt from my "Guide to transponders in sailplanes" that
describes the current situation:

> Summarizing what an SSA director involved with SSA/FAA matters told me:
>
> What we spent years doing was trying to get the FAA to agree that we could turn them
> [transponders] off if necessary. The irony here is that we are asking the FAA to legalize is what the
> pilots are already doing, and the FAA knows they are doing it.
>
> The conversation basically went something like this...
>
> SSA: "The pilots are turning them off to save battery power and keep the radio
> operating".
> FAA: "Yeah, we know".
> SSA: "We think they should be allowed to do it in remote areas".
> FAA: "We agree".
> SSA: "How do we legalize this?"
> FAA: "File a petition".
>
> So the FAA wanted us to submit a petition for "legal" reasons, and we did (Jan. 2004). We have
> glider pilots throughout the FAA building in DC and they already know all about low power
> transponders. We know that ATC has even told pilots to leave them on and turn the radio off - we all
> agree that's nuts, but it's what the rule says. They also have told us that the day after a mid-air
> between a glider and a commercial transport, we will lose our exemption. What we're trying to do is
> get agreed to procedures and policies in place before that day happens.
> Currently (Oct. 2007), the petition is still awaiting action from the FAA.

This excerpt suggests a pragmatic approach, given the current situation
is likely to persist for years:

> Can I turn the transponder off to save the battery?
>
> FAR 91.215(c) requires aircraft with a properly functioning transponder to operate it at all times while
> flying. We all know that some transponder-equipped sailplane owners conserve their battery by using
> the transponder only in areas where traffic is heaviest, and there have been no official reprimands so far.
> This is better than having a dead battery later on in the flight, when a transponder might be most useful,
> and being without a radio and other instruments.

I have never read a description of the reasoning leading up to the
"always on" rule. Perhaps someone does, or can supply references to an
explanation.
--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Guide to Transponders in Sailplanes"
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more
* http://tinyurl.com/y739x4

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org