On 4/6/15 11:36 AM, wrote:
On Monday, April 6, 2015 at 7:15:21 AM UTC-7, Andy Blackburn wrote:
I have not heard of anyone working on, or even contemplating, glider (much less balloon) anti-collision algorithms to their ADS-B solutions. In part I suspect this is because of the possibility that if you don't have all systems using the same algorithm you could generate a situation where a close-proximity anti-collision system makes matters worse rather than better. Has anyone heard of an ADS-B standards body working specifically on developing a single algorithm for collision detection/avoidance (a capability that goes well beyond detecting traffic in an envelope)? Not me. The issue is that the overall philosophy for ADS-B was developed under 5-mile/1000-foot separation assumptions. Anyone who tells you it can be easily adapted to glider scenarios is either misinformed or deliberately misleading you.

Sorry, FLARM is not an "anti-collision" system like TCAS, it is a "traffic advisory" system like ADS-B. The only thing that FLARM-specific algorithms do is reduce the number of warnings provided of nearby gliders that are determined not to be on conflicting paths. Having identical firmware in all FLARM units simplifies the programming issues and allows for use of lower-powered processors. Implementing similar algorithms on top of the more diverse ADS-B environment will not have any innate tendency towards making matters worse.

I understand the push for PowerFLARM adoption in the US, and I understand the desire to pushback on misinformed ADS-B speculation. But making crap arguments against crap arguments does not improve this situation. Eventually we will have to come to terms with ADS-B in the US soaring community, whether we like it or not.

Marc


OK so being careful on semantics is useful, yes the only
*anti-collision* system is TCAS-II, everything else is situations
awareness or traffic warning only. And to look at ADS-B, how/whether
ADS-B plays a role in any anti-collision future needs to be decided.
RTCA and the word's avionics manufactures and regulators don't have
anything close a clear path for use of ADS-B in real collision avoidance
either at the high-end where TCAS II us used today or something more
affordable for say the GA market. And to some extent they don't need to
as TCAS II while not perfect works pretty well and doing much more is an
extremely difficult problem. And hey besides everybody out there who is
a collision threat has a transponder... right?

And that leads to the double damnation with all the past talk about
UAT-Out in gliders. It did not provide TCAS II compatibility for
aircraft equipped with TCAS II, you needed a separate transponder for
that so an issue where you have lots of airliners and fast jets. But
even at a simpler level, forgetting anti-collision stuff, the
low-cost/low-power/compact UAT-Out systems talked about for gliders
can't even do situational awareness or traffic warning. There were
UAT-Out boxes with no receiver, and no display, and no integration with
common soaring displays or software etc. Not anything even as
start/proof of concept. And certainly no smarts for predicting/warning
about threats in a soaring like environment like FLARM has, and no signs
for who would ever do all that development and integration and
production and support work for a very small soaring community (and a
market effectively unique to the USA).

Especially while ADS-B remains prohibitively experience and complex at
least for a certified aircraft I don't the need for most members of the
US soaring community to worry too about it. Folks operating tow planes
in areas where they will need to comply with the 2020 carriage mandate
are the ones I most feel for at the moment, and I hope as that deadline
gets closer the product available will help reduce costs to those
operators and there is useful sharing of information between folks.
Otherwise right now it's mostly just keeping an eye on budgets and
planning for some ADS-B equipage hit for those tow planes prior to 2020.

Otherwise it's the same old same old. If you feel gliders-glider and
glider-towplane collision risks are significant equip with a PowerFLARM,
and get others locally to do the same. If the concern is
GA/Airliner/Military traffic etc. equip with a transponder. If you are
technically inclined and own an experimental glider say with a Trig
TT-21/22 then by all means play with ADS-B Out, be careful how that is
set up (I've helped several owners who want to do that get going with
1090ES Out). And those experiments could help see if ADS-B Out is useful
for things like longer-range air-air and ground trackng of gliders etc.,
SAR last location, etc. There *is* interesting and useful things that
could be looked at there. Anybody want geek help/have questions there
let me know and I'll see if I can help or find you help.

Forgetting *anti-collision*, there is still just nothing close to a
practical ADS-B Out and In (=compact, low power, affordable and
compatible with displays etc.) product(s) today that an owner would
install in a typical glider that would give traffic/collision threat
information to/from nearby ADS-B equipped aircraft. I'd like to see
folks who are still pushing ADS-B crap in the soaring community to have
some, or any, experience flying with what they keep going on about, and
to be able to describe exactly what traffic awareness/traffic warnings
works, how you integrate things, how much it costs, etc.

And we'll have to wait and see what happens with low-power Mode S
beacon/1090ES Out. Maybe technology will come along there. It's a little
too early to be able to guess. But I suspect if anything that type of
technology might end up being used in mid-size UAVs. For the soaring
community's sake I hope those systems end-up being 1090ES (not UAT)-Out
or Dual-link Out. They damn well better have Mode-S transponders, and
companies are already building some impressive Mode-S systems targeting
UAVs (like Sagetech http://www.sagetechcorp.com/unmanned-solutions/).
Hopefully the Mitre/pro-UAT folks don't get to cause a dangerous mess
there, but clearly pushing UAT-Out for UAV use is what Mitre wants to
do. Mid-size and larger UAV certainly worry me. The emergence of UAVs
and their regulation and avionics requirements, and what Mitre exactly
is doing there (they may not be working towards the best interests of
the soaring community at all, I do not see how pushing any UAT-Out
beacon technology does) would be a good area for the SSA to keep watching.