We here in the North Island are probably lagging behind this debate. However for Flarm to work you need a critical mass of gliders equipped or else it's just an expensive power hungry lump of electronics's...a bit like a transponder really.
As for PowerFlarm...it might be useful in areas with lots of flying buses and VFR power chaps with their heads inside the cockpit relying on Airways for separation...Tauranga perhaps.
More data is probably required on power consumption, accuracy and pilot behavioural change.
However, if the owner of GlideOmarama is to be believed, he won't tow gliders at future contests unless they are equipped with Flarm.
I must admit that flying north along the Two Thumb Range with dust blowing off the upper reaches of the Godley River, and gliders going in and out of the turnpoint, it was very very difficult to see approaching gliders...at a combined closing speed of 200 knots plus.
Dear ESC Friends,
Being out of town, and unable to "reply" to my shaw
email, I missed out on the recent PowerFlarm dustup, or at least I missed out
on the opportunity to stick my oar in and say something I would regret.
I am now, however, able to provide a User Report on the
PowerFlarm.
Here is a photo of the Discus and me, with the PowerFlarm
portable unit prominent on the top of the glare shield, with its distinctive
twin antennas. From what I have read, the Schempp-Hirth gliders allow the
easiest and cleanest installation, since the whole unit including vertical
antennas fit under the canopy. My unit is an early portable version, and
has not yet had the most recent hardware and software upgrades. The
portable has a small (1.5 inch?) screen which in this installation has a
prominent place in the pilot's vision. It displays the location of each
target acquired and its relative altitude. The unit has a speaker, which
issues audible warnings: alerts for proximity, and more urgent noises
when it has computed a collision course. I have the PowerFlarm connected
to the Oudie soaring computer, running LK8000, which also displays the
locations of targets on a larger screen, plus relative climb rate.
At the Ephrata contest, about 25 of the 30 gliders
participating were PowerFlarm equipped.
There are, of course, positives and negatives. I will
start with the negatives.
- In a large pre-start gaggle
- 5 or 10 gliders in one thermal within a total of 1000' of altitude, I
allocated zero scan time to the PowerFlarm. My eyes were outside.
The unit was frequently issuing alerts. As if I needed any
encouragement to be alert. Well, to be honest, one can become even
more alert - it did have that effect on me - but other than that the
information was more scary than helpful.
- Transponder data is very
fuzzy - it tells you range to target is decreasing but not the direction
from which it is coming.
- This was the main
reason for the net negative contribution from PowerFlarm in large
gaggles. If I had had the power, I would have insisted all gliders
turn off their transponders in the pre-start period.
- It was
"disconcerting" to be looking out the window, spotting guys
over there, up there, down there, and having the unit making very urgent
noises.
- Transponders show up as an
additional aircraft. One day, coming back at the end of the day, I
found myself in a thermal with another glider. I could see him
there, perfectly positioned on the other side of the thermal, just a
little below me, consistent with the Flarm display. Except the
PowerFlarm was showing two other aircraft, both "-02", or 200
feet below me. I could see one, where was the other? And the
unit was making quite a racket. That evening I had a chat with the
other pilot, confirmed there were only two of us, and confirmed he had a
transponder switched on plus a PowerFlarm.
- The PowerFlarm is not
reliable. Frequently I saw a target, e.g. 800 feet below and to the
right rear. And then it disappeared. Where did it go?
My conclusion was my unit was almost blind to aircraft directly
behind me. Antenna issues are a challenge. Therefore, the
PowerFlarm does not replace the window.
- People found it
disconcerting to see a bunch of gliders in the landing pattern area.
Turns out if you land, clear the runway, and leave the unit running,
it looks like a glider beside the runway. Well, duh! And there
is an altitude readout. Except if you get too many of them, the data
displayed steps all over itself, and anyways it is hard to figure out when
there are a bunch of targets. The morning pilot meeting safety tips
repetitively included calls to switch off the Flarm as soon as possible.
- It is a sensor. Like
any sensor, it has some accuracy and some precision. A reading of
200 foot separation can mean zero separation - all that would take is a
mis-calibration of one or both units, well within the error margin for the
technology. You can't trust it to be exact.
Positives:
- The PowerFlarm does indeed
provide a heads up when there are other gliders nearby, usually. I
found this most helpful in situations such as:
- another glider joins
you in a thermal far enough below you that the pilot does not feel the
need to join on the far side - can be below or below and behind.
You know he/she is there.
- you hit a thermal,
swing in to the core, and only then notice there is someone a thousand
feet above you - perhaps hard to spot against the cloud above him.
Then you start gaining on him (well, sometimes). perhaps you
need to reverse your turn.
- you are thermaling
away, and then notice a couple of gliders half a mile away - they are in
a different core, and circling the other way.
- O.K. you should
always see all the other gliders. Well, no, you don't. At
least, I don't - I now know that for a fact. And all the other
pilots I spoke to were willing to make the same admission. No, it
doesn't replace the window, but it does add information.
- It is fun to be able to
watch whether the folks in the next core over are doing better or worse
than you.
- It is extremely interesting
to watch the separation between you and the person below you in the same
thermal shrinking. Clearly, at some point, that glider will become
very important. Perhaps you can't see it; you now know you need to
find it, whatever that takes
- It is an OLC valid logger.
- It can feed glide
computers, which can then do very interesting things like tell you who in
the vicinity has the best thermal.
- It does display not only
other PowerFlarm equipped gliders, but also ADIS-B and PCAS (transponder
equipped) aircraft. The complaints above about transponders relate
solely to gliders carrying both units - power planes with transponders
will show up, and that is a huge benefit.
In summary:
- I found the PowerFlarm a
valuable assistant at Ephrata. It added information. It showed
me things I hadn't seen, or seen yet.
- I found it most useful when
dealing with one or two or perhaps three other targets within a mile or
two. In other words, in the environment one finds around a field
such as Chipman on a lovely afternoon.
- In normal flying, I added
it to my scan. Sitting on top of my glare shield, it is perfectly
placed to be one stop in a horizontal scan. I found myself, as I
rolled in to a thermal, starting my scan as far over my shoulder as
possible, as usual, scanning across the horizon to try to spot any
"company" already in that thermal - and as my scan traversed
across dead ahead it was a piece of cake to see if there were any
"targets" on the PowerFlarm screen. I carried on,
completed the scan, without actually "reading" what was on the
screen, then, if there was data on the PowerFlarm screen, came back to it
to actually read the numbers and compass direction of the target, to
establish direction and relative altitude. Seeing nothing there was
encouraging (my unit seems pretty reliable when banked into a thermal, no
blind spots that I could tell). The time required to include one
additional stop in the scan I was making anyways, and to shift focus for
that one stop, was, in my experience minimal and manageable.
- Other than that I rarely
even glanced at it. But it would have squawked if it had computed a
collision course. Therefore, one legitimate option is to relegate it
to solely that audible warning device role, and still gain considerable
safety benefit. In other words, speculation the PowerFlarm would be
a net safety negative - because attention to it would
compete with/decrease attention to more important or effective tasks
- is, in my experience, not correct. A valid concern, but,
in my experience, not true.
- I never looked at the
PowerFlarm data on the flight computer; I never used the LK8000 extension
of the data provided by the PowerFlarm.
- It was apparent the better
PowerFlarm installations, with the "Brick" unit and better
antennas, were better than mine.
- At Ephrata, flying without
a PowerFlarm was almost socially unacceptable. At the
morning pilots' meetings, and in numerous smaller-group discussions, there
were many comments along the lines, "if you don't have a PowerFlarm,
I'd rather you don't lurk along behind me", and "if you don't
have a PowerFlarm, please find your own thermal". It was not
brutal, or nasty, or "excluding". However, it was clear:
that particular group of experienced sailplane pilots were convinced, as
individuals, that PowerFlarm is a net safety benefit.
I would be happy to expand on any of these comments, or
answer any questions, to the whole group or in private email exchanges.
Cheers
Bruce
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