Sigh... (USA)

On Jun 9, 11:17*am, Vaughn wrote:
On 6/9/2012 1:52 PM, Kimmo Hytoenen wrote:



FLARM can be a very good system. However, there are some
issues which I am not sure if FLARM as a company is taking
seriously enough. In US PowerFLARM seems to have some
advantages over European version.

This is a report of a very unfortunate midair, which should have
been avoided. Both planes had FLARM systems installed.

http://www.turvallisuustutkinta.fi/1302672994222

FLARM is an imperfect warning system just as parachutes are an imperfect
rescue system. *Clearly (and tragically) FLARM failed to prevent the
above referenced accident. *But also notice that one pilot was saved by
his parachute, while the other unfortunately wasn't.

Does the above accident imply that parachutes are a bad investment?
Obviously the answer is no. *Parachutes clearly save lives, even though
they are imperfect.

Does the above accident imply that FLARM is a bad investment?
Same answer as above, same reasoning.

Vaughn

Could good "old" PCAS help in this situation assuming both gliders
have transponders and are being interrogated.
And for that matter the one at AirSailing (hopefully we will find out
if they had this equipment). It too is far from perfect but the alert
it gives never fails to get my attention and elevates scan to the top
priority of my pilot load(or equal with flying the plane).

On 6/9/2012 11:50 AM, db_sonic wrote:


Vaughn

Could good "old" PCAS help in this situation assuming both gliders
have transponders and are being interrogated.
And for that matter the one at AirSailing (hopefully we will find out
if they had this equipment). It too is far from perfect but the alert
it gives never fails to get my attention and elevates scan to the top
priority of my pilot load(or equal with flying the plane).

This situation may be the worst possible: the high glider is behind the
low glider, and neither can see the other. Possibly, the upper glider's
fuselage blocks the Flarm signals in both directions. PCAS might provide
a notification that the other glider was present (if at least one glider
had a transponder and the other the PCAS), as the glider positioning
would not interfere with transponder signals.

Still, a PCAS system would not warn you that a collision was imminent,
as it can not detect what appeared to happen: a quick pull up, perhaps
triggered by hitting some lift. How often do we do that, without
checking behind and above first? I do it a lot as I travel along under a
cloud street, and I know others also do it.

Maybe we need a mirror positioned to easily see that blind spot.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

I think that if Flarm were installed with 2 antennae, one high in the
cockpit or on top of the fuselage, and the other below, there would be
no Flarm blind spot and it would be as near perfect as possible. We
don’t do that because it is too much trouble and/or too expensive. It
is hard enough to persuade many pilots to have Flarm even in its most
basic available form.

Similarly, if we all had blind spot mirrors, the chance of seeing a
potential collision as the Finland one would be improved – but not
perfect still, as the human eye and attention is not capable of
perfection. Downward and rearward facing CCTV would be a further
enhancement of visual collision avoidance. (The latter is coming in on
road vehicles, so not technically impossible, just expensive to
develop and install.) Have we done it? No – “it isn’t worth it”.

As for PCAS – I have one of those too. I have only an aerial on top of
the glare shield. AIUI, transponders in gliders with only one antenna,
usually underneath, will have weak or non-existent signals upwards,
and my PCAS will only see at very shallow angles down, so would not
help in the Finland type accident if the lower glider had only a
transponder and only the upper one a PCAS.

As I have said before, the best is the enemy of the good. If everyone
waits for the best/perfection, we will have too many fatalities that
meanwhile the good – Flarm + PCAS – can help avoid some, or most,
times.

Chris N.

On 6/9/2012 4:16 PM, Chris Nicholas wrote:

As for PCAS – I have one of those too. I have only an aerial on top of
the glare shield. AIUI, transponders in gliders with only one antenna,
usually underneath, will have weak or non-existent signals upwards,
and my PCAS will only see at very shallow angles down, so would not
help in the Finland type accident if the lower glider had only a
transponder and only the upper one a PCAS.

As I have said before, the best is the enemy of the good. If everyone
waits for the best/perfection, we will have too many fatalities that
meanwhile the good – Flarm + PCAS – can help avoid some, or most,
times.

The transponder signal is so powerful (150+ watts) compared to a Flarm
signal (0.02 watts), a PCAS unit would be able to "see" a transponder
equipped glider, even in the situation in Finland. Also, the glider
above would almost certainly have it's transponder antenna on the
bottom, while the glider below would have it's PCAS antenna "on top"
(glare shield mounted) and have no trouble receiving it.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

PCAS is useless for gliders flying intentionally in proximity, e.g. in
thermals. Range is based on signal strength, altitude is based on
pressure altitude encoder and there's no directionality. Best that
PCAS would tell you is that there are "n" gliders close to you. It
certainly can't give collision warning.

-Evan Ludeman / T8

On Jun 9, 8:23*pm, Evan Ludeman wrote:
PCAS is useless for gliders flying intentionally in proximity, e.g. in
thermals. *Range is based on signal strength, altitude is based on
pressure altitude encoder and there's no directionality. *Best that
PCAS would tell you is that there are "n" gliders close to you. *It
certainly can't give collision warning.

-Evan Ludeman / T8

Sorry Evan but that is not completely correct. While I agree that
PCAS can only offer very limited collision avoidance it certainly does
help. Speak of the devil I have video to prove it! Check out the
following which is just one of many videos showing close sailplane
formation and PCAS proximity warnings. Note my PCAS warns me that I
am drifting too close to the other transponder equip ship. I am all
for Power Flarm and have one on order but please note that the PCAS
does offer at least a little bit of help. Better than nothing...that
is when it works. My Zaon PCAS has stopped working 3 times with no
warning other than it didn't alert me to a close aircraft giving me a
hint that it stopped working again. Grrrr!

http://www.youtube.com/watch?v=n2H4SQpjRxc

The PCAS warnings come at :18, :27 (note how the sailplane is drifting
towards me), :46, 1:14 and on and on throughout the video. Again,
I'll take Flarm any day of the week but I guess they have to start
shipping our brick units first. Another Grrr.

Take care,
Bruno - B4

On Jun 9, 11:09*pm, Bruno wrote:
On Jun 9, 8:23*pm, Evan Ludeman wrote:

PCAS is useless for gliders flying intentionally in proximity, e.g. in
thermals. *Range is based on signal strength, altitude is based on
pressure altitude encoder and there's no directionality. *Best that
PCAS would tell you is that there are "n" gliders close to you. *It
certainly can't give collision warning.

-Evan Ludeman / T8

Sorry Evan but that is not completely correct. *While I agree that
PCAS can only offer very limited collision avoidance it certainly does
help.

Don't be at all sorry if it works for you!

Different environments.

In dense gaggles in crappy wx at 15s we got *frequent* flarm alerts...
because the flying was just that close. Was it annoying? Not
exactly. All the alerts were meaningful. Think of having a back
seater with omnidirectional vision calling out traffic (4 oclock
high.... 3 oclock level, etc), stuff you needed to know about, mostly
already knew about. Did it prevent a collision? We can't know.
Flarm tells you early enough that the corrections needed are small and
the conflicts never develop into scary situations. The most
interesting alert was when Flarm called out three targets at once, oy.

If we'd all been on TXPs and PCAS, a) half the time we'd have had no
coverage because were below the radar, b) other times we'd have had 30
contacts inside a half mile and 400 vertical feet. I don't see how
PCAS could have provided meaningful information in that environment
and that's the environment I was thinking of. Your mileage, and
collision avoidance requirements may vary!

-Evan Ludeman / T8

Also, the glider
above would almost certainly have it's transponder antenna on the
bottom, while the glider below would have it's PCAS antenna "on top"
(glare shield mounted) and have no trouble receiving it.

Eric, only if they both have both transponder and PCAS. Re the
stronger signal, you may well be right – I don’t know.

But PCAS of course does not distinguish between proximity but going to
miss, and proximity and going to hit. My unit also only knows in
1/10ths of a mile the approximate distance. Still, better than
nothing, of course.

Chris N

On 6/9/2012 7:33 PM, Chris Nicholas wrote:
Eric, only if they both have both transponder and PCAS. Re the
stronger signal, you may well be right – I don’t know.

One could have the PCAS, the other could have the transponder, and the
PCAS glider would be alerted to the other glider. Better, of course, if
they both had PCAS and transponder.

Transponders do have very powerful transmitters, and it is one reason
they cost as much as they do. Look at the specifications at any website
selling them - the power ranges from about 130 to 250 watts (our
communication radios are typically 5 to 7 watts). That power is needed
to reach the ground radars that might be 30 to 150 miles away.

Flarm, including PowerFlarm, is designed for air to air ranges of a few
miles, and doesn't need very much power to do so.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

On Jun 10, 1:16*am, Chris Nicholas wrote:
I think that if Flarm were installed with 2 antennae, one high in the
cockpit or on top of the fuselage, and the other below, there would be
no Flarm blind spot and it would be as near perfect as possible. We
don’t do that because it is too much trouble and/or too expensive. It
is hard enough to persuade many pilots to have Flarm even in its most
basic available form.

Chris N.

That's what I decided on last winter., because the Flarm range
analysis on my carbon fuselage Flarm installation (Ventius cM) showed
that there were some blind spot (ranges 2km). I installed an antenna
splitter, the original Flarm antenna outside the fuselage near the
gear doors, and a stripe antenna behind my head inside the canopy.
"Blind spot" now means a range of 4 km ( a bit more than 2 nautical
miles for the colonials).
Investment was $200. My ass is worth more than that.