Darryl Ramm wrote:
On Jun 8, 11:18 am, Andy wrote:
On Jun 8, 5:50 am, Frank Whiteley wrote:

http://tinyurl.com/m89o8l
Well she's persistant, but seems to lack focus. She also appears to
disregard feedback that transponders would have made no difference in
the fatal accidents she cites.

Now if she could just focus on low cost ADS-B and get that
implemented, I might take out a subscription to her rag.

Andy (I'm this Andy, not that Andy)

Oh here we go again.

And what exactly would low-cost ADS-B solve? And how do you define low-
cost? Current Mode-C and some new Mode-S transponders are already
pretty low cost (for an avionics device), are pretty reasonable on
power consumption and fairly compact.

ADS-B-out UAT devices have issues with needing proper static pressure
sources and certified GPS data, that has been discussed before. The
certified GPS issue alone may keep them much more expensive than
transponders.

But even is those issues were solved would it result in what we really
need for fast jet and airline traffic avoidance? Probably not...

ADS-B-out UAT (the supposed low cost devices) have problems that most
fast jets and airliners are not equipped to receive UAT data or
certainly not to utilize this as a part of TCAS. While ATC will see
that traffic the airliners we especially want to avoid running into
will not. TCAS is critical for these aircraft as its the last part of
the safety net in traffic avoidance. There is no TCAS integration with
ADS-B UAT data and there is no standard to do so - except that an
appropriately equipped TCAS unit will use the ADS-B position data to
minimize it's interrogation of a target. TCAS never issues a TA or RA
based on ADS-B UAT data. That whole world of big fast shiny things we
don't want to run into assumes that traffic is also transponder
equipped.

There is also the whole issue of market demand. it is not clear to me
that that the split UAT/1090-ES idea is going to work. Many GA
aircraft already have or will install a 1090-ES capable transponder
and can get good weather services via XM-WX. If they have Mode-S (with
1090-ES to meet any mandate) why would they add a UAT? Maybe UATs will
take off, but some of the drivers for adoption that the FAA talked
about at the beginning don't seem that compelling. Two different
physical layers (UAT and 1090-ES), confusion between ADS-B data-out,
data-in, TIS-B, FIS-B etc., UAT incompatibility with current TCAS and
PCAS traffic systems, lack of UAT products, competing technology like
XM weather all make this interesting to watch.

And as piece of futureware that can keep people entertained forever
with "what if" dreaming and as a reason to avoid adopting transponders
now (where they are needed in high density airline/fast jet traffic
areas) ADS-B UAT is *great*.

I'd add to Darryl's notes that it's not clear when the *ground stations*
required for ADS-B will be in service for all the areas we fly,
especially out west. Without the ground stations, ATC can't tell anyone
in contact with them where you are; without a transponder, detectors
like the Zaon MRX won't work. I'm not aware of any device available to
tell you where the ADS-B equipped aircraft are either, unless you have
the Garmin UAT ($7000 shoebox sized unit).

If anyone has information relating to ADS-B that contradicts what Darryl
and I believe, please contact me about (email, phone, whatever - check
the SSA member locator for if you don't know already). I'm beginning
work on an article on transponders vs ADS-B for a Soaring magazine
article this year.

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

* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* Sections on Mode S, TPAS, ADS-B, Flarm, more

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