Parowan midair?

On Jun 30, 9:35*am, Greg Arnold wrote:
On 6/30/2010 8:20 AM, Mike Schumann wrote:



In the US, there are no FLARM units. It's a chicken and egg situation.
The 1st person to install a FLARM unit would see no benefit. As more
people deploy these units, then the benefit would increase.

In the US, for most glider pilots, the major threat to collisions is not
other gliders, but other general aviation powered aircraft. What is the
realistic chance of getting these pilots to buy / install FLARM? ZERO!

If I correctly understand the forthcoming PowerFLARM, it identifies both
other gliders that have FLARM, and any aircraft that have transponders.
* I would think that glider pilots will first buy it to identify
transponders, and that is how we will achieve the critical mass of FLARM
units in gliders.

To the earlier point, I don't suspect anybody, includign Flarm, thinks
that the Flarm radio-protocol would be widely adopted in the GA market
in the USA. I think that was one of the points that Urs (CEO of Flarm)
was trying to make in his post about why the PowerFLARM is more
suitable for the USA market.

I suspect Greg understands PCAS well, but as with any of this
technology I want to be cautious about how some people will understand
statements like PowerFLARM seeing "any aircraft that have
transponders". The PowerFLARM (with 1090ES/PCAS option) includes PCAS
capability that will give some warning/traffic information about
transponder equipped threats. The PCAS threat information will not
include direction, only altitude and there is no detail available yet
AFAIK on how many threats etc. the PowerFLARM tracks/warns about/the
alert parameters/settings etc. So basically think of this like a Zaon
MRX built into the PowerFLARM box. If it works as well as the MRX it
is a great useful feature to have. However as with all PCAS it relies
on the transponder in the treat aircraft being interrogated either by
ground based SSR or by airborne TCAS or TCAD systems. Those of us who
fly with the MRX today know the coverage of these interrogators can be
pretty good, and that PCAS can be a great help in traffic awareness
but there are areas where there are no interrogator coverage (esp. low
on ridges, down low in valleys). PCAS is also of very limited if any
use in gaggles, even if the other gliders are all transponder
equipped. PCAS systems also often do not have enough range to provide
effective/early enough warning of fast jet traffic (esp. at
altitudes). If the concern is fast jets/airlines the most effective
thing to do is carry a transponder so those aircraft TCAS systems see
your glider and in the worse case issue a traffic resolution (TA)
command to the pilot. That is much more effective than hoping you can
use traffic awareness devices to help you avoid that fast jet.

The PowerFLARM (with 1090ES/PCAS option) also includes an ADS-B 1090ES
receiver. So will directly receive ADS-B data from 1090ES data-out
equipped aircraft. Which as the fleet adopts ADS-B this means the
PowerFLARM will see the position of 1090ES equipped airliners, jets
and likely much of the GA fleet. For those concerned with fast-jets/
airlines the 1090ES data-in capability in the PowerFLARM (without any
other devices, ADS-B transmitters etc.) will let you see those (1090ES
equipped) aircraft position precisely and at much longer range than
traditional PCAS systems. Bit again, this is a compliment, but not a
good alternative, to having a transponder in your glider to make you
visible to those aircraft's TCAS systems.

In the USA we have a complex dual-link ADS-B environment with both UAT
and 1090ES data-links supported. The FAA seemed to be assuming the GA
fleet would predominately equip with UAT devices. I beleive this is a
bad assumption and much of the GA fleet is likely to equip with 1090ES
data-out. Especially since, to meet requirements for flight in much of
the airspace those GA aircraft need to equip with both a transponder
and ADS-B data-out. Vendors like Garmin seem to be pushing just going
to Mode S and combining both capabilities in one box, which is what
they have done with the GTX-330ES/33ES products. Since common
components, packaging and costs can be combined this makes a lot of
sense.

In the USA a PowerFLARM will directly see the ADS-B transmission of
1090ES data-out equipped aircraft. But what about UATs and TIS-B?...
ADS-B dual-link works by utilizing GBT ground stations to relay
between 1090ES and UAT and visa-versa (that's called ADS-R or ADS-
Relay) and to also transmit the position of SSR radar based traffic
(that's called TIS-B). To do this the ground infrastructure needs to
know your aircraft's location so it can broadcast threats in your
vicinity. To do this your aircraft must be equipped with an ADS-B
transmitter, either a UAT transmitter (or transceiver) or Mode S
transponder with 1090ES. And the transmitters need to be fed a GPS
signal and correctly configured to tell the ground infrastructure what
ADS-B receiver capability your aircraft has. Just trying to get this
set up is a confusing mess today, and may not get any better--we are
likely to have lots of cases of improperly configured devices with
pilots unaware they are not working correctly.

Currently the PowerFLARM is the most interesting looking traffic
awareness product for gliders in the USA. It meets the baseline
requirement of being relatively compact and low-power. At around
$1,700 (with PCAS/1090ES) it is a bit more than many pilots would like
to pay, but for an early device with all these capabilities it is a
pretty amazing price point. The PowerFLARM has a nice built-in
display and audible warnings (fancier voice coming after first ship?)
and presumably supports Flarm's proven good glider-tuned collision
avoidance logic for Flarm as well as ADS-B direct and ADS-R traffic
(not sure how really handles the less precise location of TIS-B
threats). It supports the defacto standard Flarm serial protocol for
connection to remote displays, PDAs etc. Remember just having ADS-B
data-in anything provides no guarantee of a traffic/collision warning,
and certainly not something tuned for glider-on-glider situations like
Flarm has developed in their previous products. I am not aware of any
UAT devices, including the NavWorx products or the Mitre prototypes
that come close to having all these features, pretty much what I
consider baseline features for use in gliders. And based on a question
I posed to NavWorx, they appear to have no interest in supporting the
Flarm serial display protocol in their products. That's pretty
understandable since their products are really intended for the GA
market (e.g. their UAT transceiver appears to be packaged for GA
applications and to have relatively high power consumption for our
uses).

In the USA it is pretty clear we are going to be operating in an
environment with both 1090ES and UAT devices. We will have issues with
glider and GA aircraft owners (esp. early adopters and those not
seeking to meet carriage requirements) not being aware they need to be
ADS-B data-out equipped for ADS-R and TIS-B to work properly and we
will have areas without GBT coverage for ADS-R and TIS-B. For us I
worry about mountain ridges and valleys and similar areas where UAT
and 1090ES equipped gliders will not be able to "see" each other. I
worry that the only real ADS-B solution that will "just work" will
require the eventual adoption of dual-link receivers to directly
receive both 1090ES and UAT -- but even then we will need all gliders
to equip with an ADS-B data-out device for ADS-B to work. Or we all
adopt PowerFLARM and rely on the Flarm-Flarm link for glider on glider
traffic awareness in those corner cases. The SSA is supposed to be
working with the FAA on ADS-B, hopefully they are looking at lots of
these practical issues, not just focusing on the Mitre UAT prototype.

The nice thing about PowerFLARM (with the 1090ES/PCAS option) is that
with no extra work it gives you PCAS, 1090ES direct-in and Flarm to
Flarm capability today. Flarm-Flarm only being interesting if you can
convince lot of you local your glider buddies to buy one as well.
Early adopters today who want to play with ADS-B "properly" with a
PowerFLARM will need to add a ADS-B data-out transmitter. Probably the
most practical way of doing that today in the USA would be based on a
Trig TT-21 1090ES capable transponder.

All this of course is buried in a thread about a real collision. All
these devices are just aids and I really hope people posting about
technology here really really really get that....


Darryl