Just a short note to update everyone on the progress of FLARM implementation in the U.S. in general, and at Mifflin in particular.

There are now at least half a dozen or so ‘brick’ installations up and running here at Mifflin, and from all reports they are working well.  Pilots report 3-5 mile  range for detection, with correspondingly ample time to see and avoid problematic gliders before they become problematic.  In addition, if a glider *does* become problematic, the FLARM seems to be very good at alerting both pilots of the situation.

The cause of the range problems I was seeing with my portable unit at the Seniors and again at Perry has been identified with a high degree of certainty as out-of-band interference.  As it turns out, most FLARM receivers have a fairly  wide open RF passband, due to the slightly different RF frequency requirements for different countries.  However, in the U.S. there is apparently some nearby interfering signals that essentially desensitize the FLARM’s receivers, giving rise to the range  issues we have been seeing.  The current solution to the problem is to add a front end narrowband filter to the receiver to block out all the nearby interfering signals, giving the receiver a nice quiet channel to listen on.  All the ‘brick’ units have this front end filter in place, and the test FLARM unit I used yesterday had one channel without the filter, and one channel with it, and the difference in flight was that I could now see FLARM hits from much farther away.  In fact, yesterday I was able to see and avoid an opposite direction glider under a huge street where we were both up near cloudbase – the ‘OCallahan’ accident scenario.  The only downside to installation of the front-end filter is that U.S. units won’t be directly usable overseas (in Europe and/or Australia for instance).  However, that shouldn’t be a big consideration compared to the benefits of having widespread FLARM implementation here.

There is one other problem that has cropped up here at Mifflin with FLARM units, and that is the polarization of the display units.  Apparently a few of the displays were manufactured with a display polarization that is 90 degrees out from the rest, with the result that a pilot trying to view the display with polarized sunglasses has to tilt their head (at least) 45 degrees to the side to see anything.  Dave Nadler has been appraised of this problem, and he told us that the factory is aware of the problem and is taking steps to make sure all the display units have the correct polarization.

So, it appears we are nearing the end of the ‘teething pains’ phase of FLARM implementation here in the U.S. , so if you have been holding off ordering a FLARM unit, I urge you to reconsider – we need a high percentage of FLARMs in the cross-country and racing fleet to make the whole thing work.  Although the rules committee was adamant that they have nothing on the drawing boards, I predict that FLARM will be mandatory at Nationals within 2 years, and regionals in 3.  There is still the issue of the display unit, so I urge anyone ordering a brick or a portable to immediately check for this problem upon receipt of their unit, *before* installation.  If the display exhibits the problem, immediately notify the vendor and get a replacement  display.

Stay tuned  – I’ll provide more updates as they become available

Frank (TA)