Feds Want to Equipe Gliders With Transponders and Radios

I came across this technology on the web when I was researching the recent
ADS-B nprm. Looks like there's already some portable/handheld ADS-B type
equipment in use in Europe for the soaring community:

http://www.rf-developments.com/shop/...d&productId=26

http://www.rf-developments.com/shop/...d&productId=33

All based on some SSA technology called FLARM:

http://en.wikipedia.org/wiki/FLARM

Maybe this will be a low cost answer to spamcans being forced into the ADS-B
regs.

Hrm. These devices are all based on something called FLARM. FLARM
works by detecting each aircraft's location via GPS and broadcasting
it on a license-free radio frequency. There are 2 things about FLARM
that make me uncomfortable:

First, the information needed for third party manufactures to build
FLARM compatible devices is not public. This means that Joe Bloggs
Avionics Corp can't build their own FLARM device at a cheaper price.
Instead you must buy from the FLARM company or another company that
has licensed FLARM. Imagine if transponders were like this! There
would be a government sactioned monopoly. I'm sure you can guess if
the price of transponders would be higher or lower then at present.

Secondly, as far as I know, all FLARMs are time-bombed. They stop
working after a certain date. After that time, you have to upgrade the
software to make it work again. Sure, this doesn't cost anything, but
what if the FLARM company goes bankrupt? If you can't get software
updates, your FLARM stops working!!

Disclaimer: I've had some personal involvement with the FLARM that's
left a bitter taste in my mouth. Back at university, I tried to make a
FLARM compatible device as a project. FLARM marketing material said
that the information to make third party devices compatible with FLARM
would be provided on request, in the interest of safety - after all,
the more aircraft fitted with anticollision systems the better. When I
actually asked for this information I was told no, it was not public
information after all. Sorry we changed our minds - you now have to
buy a license for all the electronics. I think it's wrong to promote
your product by saying it will be an open standard, then changing your
mind when it starts to get adopted.

I'm not saying that FLARM is a bad product; far from it. I've flown in
FLARM equipped gliders and feelt much safer doing so. But please keep
these points in mind.

Cheers

Al

On Apr 28, 6:24*pm, sisu1a wrote:
On Apr 27, 3:45 pm, Larry Dighera wrote:





On Sun, 27 Apr 2008 15:03:33 -0700 (PDT), WingFlaps
wrote in
:

On Apr 28, 9:32 am, Larry Dighera wrote:
On Sun, 27 Apr 2008 12:34:55 -0700 (PDT), WingFlaps
wrote in
:

A radar reflector like they use on weather balloon ought be
sufficient. It is just a piece of foil with a large cross section..

That's a constructive suggestion.

How large must such a radar reflector be?

It's a retroreflector, I have one in the form of a tube about 3 inches
in diameter and 2 feet long. The corner cubes are inside that. I have
no idea how effective it is compared to a classic reflector which
occupies *a cube about 1 foot across and retroreflects the radar
equally in all directions.
...

Interesting. *Thanks for the information.

How do you think it might affect a sailplane's L/D?

Well, if the sailplane skin is transparent to radar a big reflector
could be mounted inside, they don't weigh much. On the other hand a
cylinder type reflector could be made quite aerodynamic and even
incorporated into (say) the wing tips?

Cheers

That sounds like a very simple, inexpensive and effective solution to
the issue. *Best of all, the pilot can't turn it off. *:-)

Unfortunately too simple. The problem is NOT ATC's equipment having
trouble painting a glider. The problem is the threshold of sensitivity
on their radars is set far too high to display us since they
intentionally filter out things as slow as a glider, particularly if
it's thermalling. We are simply filtered out as clutter (according to
the rep Reno sent to address PASCO last winter). That said, I'm sure
we don't all read the same on radar, but gliders are not the stealth
aircraft they are being made out to be. I believe cockpit alone has a
rather large signature, unless of course you paid the extra $1,000,000
for the one molecule thick layer of electrically deposited gold on
your canopy. There's more to a stealth aircraft then it being made of
fiberglass, or even carbon...


Only perfectly flat surfaces are more stealthy because they bounce the
radar away from the source, whereas a convex surface always bounces
some energy back (falling rapidly with distance). A concave surface
starts to act as a retroreflector. I am sure that the nicely curved
body of a high performance glass glider has a much lower radar cross
section than any aluminium GA aircraft. It's not stealth but
fiberglass is so transparent it's used for radomes.

Cheers

sisu1a wrote in
:

On Apr 27, 3:45 pm, Larry Dighera wrote:
On Sun, 27 Apr 2008 15:03:33 -0700 (PDT), WingFlaps
wrote in
:



On Apr 28, 9:32 am, Larry Dighera wrote:
On Sun, 27 Apr 2008 12:34:55 -0700 (PDT), WingFlaps
wrote in
68afa9fb-b4d2-4620-91e6-f0a85a75d...
@x19g2000prg.googlegroups.com
:

A radar reflector like they use on weather balloon ought be
sufficient. It is just a piece of foil with a large cross
section.

That's a constructive suggestion.

How large must such a radar reflector be?

It's a retroreflector, I have one in the form of a tube about 3
inches in diameter and 2 feet long. The corner cubes are inside
that. I have no idea how effective it is compared to a classic
reflector which occupies a cube about 1 foot across and
retroreflects the radar equally in all directions.
...

Interesting. Thanks for the information.

How do you think it might affect a sailplane's L/D?

Well, if the sailplane skin is transparent to radar a big reflector
could be mounted inside, they don't weigh much. On the other hand a
cylinder type reflector could be made quite aerodynamic and even
incorporated into (say) the wing tips?

Cheers

That sounds like a very simple, inexpensive and effective solution to
the issue. Best of all, the pilot can't turn it off. :-)

Unfortunately too simple. The problem is NOT ATC's equipment having
trouble painting a glider. The problem is the threshold of sensitivity
on their radars is set far too high to display us since they
intentionally filter out things as slow as a glider, particularly if
it's thermalling. We are simply filtered out as clutter (according to
the rep Reno sent to address PASCO last winter). That said, I'm sure
we don't all read the same on radar, but gliders are not the stealth
aircraft they are being made out to be. I believe cockpit alone has a
rather large signature, unless of course you paid the extra $1,000,000
for the one molecule thick layer of electrically deposited gold on
your canopy. There's more to a stealth aircraft then it being made of
fiberglass, or even carbon.



You fly Sisu?


Bertie

On Apr 27, 1:15*pm, Larry Dighera wrote:
On Sun, 27 Apr 2008 11:06:21 -0700 (PDT), "F. Baum"

Just to clarify, The FAA does not classify a glider as an airplane so
this has nothing to do with the exemption. The press release is poorly worded.


I believe this is the NTSB Safety Recommendation Letter dated March
31, 2008:

Gee, thanks. I was aware of this. I was trying to point out that this
has nothing to do with vintage planes without an engine driven
electrical system. You dont normaly see a champ flying wave at 16000
MSL. The manor in which sailplanes are flown is what makes this an
issue.

"Big John" wrote in message
...
On Sun, 27 Apr 2008 10:09:57 -0700 (PDT), Andrew Sarangan
wrote:


Does ATC use skin paint any more????

Big John

Yes. The story I heard was that they were about to do away with it--but
some sort of incident occured in the third quarter of '01 and they changed
their minds...

Peter

On Mon, 28 Apr 2008 05:10:42 -0700 (PDT), "F. Baum"
wrote in
:

On Apr 27, 1:15*pm, Larry Dighera wrote:
On Sun, 27 Apr 2008 11:06:21 -0700 (PDT), "F. Baum"

Just to clarify, The FAA does not classify a glider as an airplane so
this has nothing to do with the exemption. The press release is poorly worded.


I believe this is the NTSB Safety Recommendation Letter dated March
31, 2008:

Gee, thanks. I was aware of this. I was trying to point out that this
has nothing to do with vintage planes without an engine driven
electrical system. You dont normaly see a champ flying wave at 16000
MSL. The manor in which sailplanes are flown is what makes this an
issue.

While the NTSB Safety Recommendation Letter dated March 31, 2008 seems
to be a request for the FAA to remove the glider exemption from the
regulation(s) regarding mandatory transponder operation, it does also
mention aircraft manufactured/certified without electrical systems.

One wonders why the NTSB would only "close the door" half way on this
issue.

On Mon, 28 Apr 2008 04:20:30 GMT, Eric Greenwell
wrote in igcRj.6716$r12.4153@trndny03:

Larry Dighera wrote:

...
Interesting. Thanks for the information.

How do you think it might affect a sailplane's L/D?

Well, if the sailplane skin is transparent to radar a big reflector
could be mounted inside, they don't weigh much. On the other hand a
cylinder type reflector could be made quite aerodynamic and even
incorporated into (say) the wing tips?

Cheers

That sounds like a very simple, inexpensive and effective solution to
the issue. Best of all, the pilot can't turn it off. :-)

Locally, approach radar has no trouble finding our transponderless
gliders (when we call them), tracking them, and warning/diverting other
traffic. We generally do this within 15-20 miles of our towered
airports. It works well for us, given the altitudes we fly at.


Thank you for this information.

Would the gliders you mention be of glass-fiber, aluminum, or
carbon-fiber composite construction? I would expect a glass ship with
few metal parts to be rather transparent to radar.

I don't know that a corner reflector would improve on the situation, or
if they would detect the gliders without the radio call. While the pilot
can't turn it off, it may be the controller doesn't notice it without
the radio call, and may not be able to see it because of other clutter,
or perhaps the display filter settings.

I would guess the controller would need to adjust his scope from it's
usual setting to see primary targets, so a radio call may be
necessary. While a corner reflector would doubtless increase the
radar energy returned to the radar antenna and provide a brighter
primary target, I doubt that would be sufficient to cause the glider
so equipped to become visible on ATC's scopes without reconfiguring
them to display slow-moving primary targets.


It's worth contacting ATC in your area to see if they are willing and
able to do the same for you. It's not practical everywhere, but it's
cheap and easy if it is.


I'm not so much concerned about my personal situation as I am about
the FAA rescinding the glider exemption from FARs that require
transponder use. If we can give the FAA some guidance on this issue,
the outcome will likely be more acceptable, than if the draft their
NPRM without pilot input, IMO.

A problem the reflector can not solve is TCAS will still not detect the
glider. This might be deal-breaker for the FAA/NTSB people.

I agree. But rescinding the glider exemption from FARs requiring
transponder use won't address that issue with powered aircraft that
lack an electrical system either. It looks like the FAA's response to
this NTSB recommendation is destined to be a compromise at best.
Hopefully it won't result in all gliders and aircraft without
electrical systems being grounded until they have transponders
installed and signed off.

On Sun, 27 Apr 2008 21:27:54 -0700, "BT" wrote
in :

Larry.. DO you fly gliders?

Not in several years.

From these statements it would appear that you do not.
Gliders may or may not have electrical systems, they do not "generate
power", but stored battery power of a limited life span.
Gliders are small, batteries are small, everything needs to be small.


None of the gliders I have flown have had electrical systems, small or
otherwise.

NTSB "recommends", FAA cannot mandate without a comment period and a change
to many CFRs.

True, but I'm thinking that it is in our best interest to provide some
guidance to the FAA before they draft their NPRM; hopefully proactive
will be better than reactive.

Technology is coming for the small transponder, along with ATS-B.

Are you able to provide any specific information about that
technology?

Why would I put a 50# $15K ATS-B system in a $15K glider.

Of course, it's worse than that. There would need to be antennas,
cabling, batteries, switches, circuit breakers, ammeter, ... It
wouldn't be very cost effective to equip gliders used for training
with all that, not to mention the resulting degraded flight
performance and maintenance requirements.

Small transponders now are about $1300 plus antenna and installation. It can
be done.

Can you provide more specific information about them?


My issue is not with TCAS equipped aircraft, but with smaller GA aircraft
that do not have TCAS, do not have a Garmin 430 with TIS (or equivalent) and
are not talking to ATC. It does no good to have a transponder, when the
aircraft causing the traffic conflict is not talking to anyone. Just sitting
there FDH and not even paying attention in the traffic pattern.


I'm not sure if there is a solution to that issue short of having a
control tower at _all_ fields. Have you got any ideas?

Last Saturday we had at least 4 transient aircraft attempt to land at the
airport with 15 to 20 knot tail winds, and against the flow of traffic.

While not very smart, it's not a violation of regulations, is it?

They could not even listen up to the radio to figure out the runway in use,
or even look at a wind sock or a huge flag and see the 15knt winds and make
up their own mind about the landing runway.

I find the level of competence, diligence, and responsibility of some
airmen to be disappointing, and it's not just the "hobby" pilots. One
wonders how they manage to pass their biennial flight reviews.


What makes you think a transponder in a glider would make any difference.


Ha ha!

Hey, it's not me raising the transponder issue; it's the NTSB.
http://www.ntsb.gov/recs/letters/2008/a08_10_13.pdf

And local ATC can see my non-transponder equipped glider just fine, when I
am high enough for radar coverage.

How much metal and/or carbon-fiber does your glider contain?

It's called raw radar skin paint.

In you experience, doesn't the controller normally need to be asked to
set that mode on his scope? Wouldn't your glider be invisible to ATC
under normal circumstances without you calling and informing the
controller you are there?

And yes, I am looking at the requirements
(Not Govt' requirement but electical and space in the aircraft requirements)
and feasibility for installing transponders in our gliders.


If the NTSB gets their way, there will be many more glider owners
doing the same.

Larry Dighera wrote:


Perhaps it would be possible to modify ATC procedures or display
software to overcome that issue. That would certainly be preferable
to requiring electrical systems be installed in all gliders.

Not to ATC.

On Sun, 27 Apr 2008 23:24:48 -0700 (PDT), sisu1a
wrote in
:

[radar corner reflector suggestion snipped]


That sounds like a very simple, inexpensive and effective solution to
the issue. Best of all, the pilot can't turn it off. :-)

Unfortunately too simple. The problem is NOT ATC's equipment having
trouble painting a glider. The problem is the threshold of sensitivity
on their radars is set far too high to display us since they
intentionally filter out things as slow as a glider, particularly if
it's thermalling. We are simply filtered out as clutter (according to
the rep Reno sent to address PASCO last winter).

Perhaps it would be possible to modify ATC procedures or display
software to overcome that issue. That would certainly be preferable
to requiring electrical systems be installed in all gliders.

That said, I'm sure we don't all read the same on radar, but gliders
are not the stealth aircraft they are being made out to be. I believe
cockpit alone has a rather large signature,

What is there in the glider cockpit of a typical glass ship that
reflects radar energy? I suppose the instruments are metal, and some
of the control linkage and gear are metallic, but I would expect the
corner reflector to provide a much stronger return.

unless of course you paid the extra $1,000,000 for the one molecule
thick layer of electrically deposited gold on your canopy. There's
more to a stealth aircraft then it being made of fiberglass, or even
carbon...

Paul

I would think carbon-fiber composite would be nearly as reflective to
radar energy as aluminum.

The issue in equipping gliders with transponders, the way I see it, is
the high power consumption required by transponders. Here's a typical
glider transponder: http://www.airplanegear.com/becker.htm
It seems to draw 175W to 250W. That's not insignificant, and way more
than the comm radio consumes. Then there's the weight and antenna
that reduce performance, not to mention the cost of the equipment,
installation, and maintenance.