Thursday, July 11, 2013

PowerFlarm...

This e-mail turned up this morning. An interesting read. (thanks to David Scott for thinking of passing it on and to the author Bruce from Canada)
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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