FLARM - equipment options and how well does it work around Europe?

I’ll put it here so I don’t pollute the Monroy thread:

Peter wrote:

What I will point out is that it is unlikely to work as is often claimed – simply because almost no powered GA carries it.

Claimed by whom? As I wrote, the target audience doesn’t care that much about powered GA. With the exception of TMGs and towplanes which are not the powered GA you’re talking about. Sure, it would be nice, but it’s a workable compromise – as I wrote, sailplane is most likely to hit another sailplane and if it hits a SEP, it will most likely be a towplane, your kind of GA is just too far down the list. That market is specific because everything runs off batteries so consumption is critical and competitive pilots will want something like 7 hours or even more of battery life. And you can’t rely on someone else “lighting up” the targets. So it probably won’t be served well by a technology developed for another corner of the GA.

I think we agree

Claimed by whom?

Lots

Peter wrote:

AIUI, with say a GTX330, if you turn it on, you get Mode S always (which can be AIR or GND mode, so let’s assume AIR mode). Then you can control whether you radiate Mode A (no altitude, just the squawk) or Mode C (altitude and squawk).

Doesn’t that switch control only replies to Mode A/C interrogations? That is, it would still be possible to get altitude via Mode S interrogation using surveillance/ altitude request message. Just a stab at it.

I don’t know why they put it there but I would expect capability to actually mean capability – not that you can turn it off when the aircraft is capable of it. That would be subject to pilot preference/ configuration.

Sorry I don’t understand. The link I referenced which was subsequently cut and pasted on here says that in Elementary Mode there is a report of Altitude in 25 ft increments. So Altitude is reported.

When you say you see mode S targets with no altitude isn’t that just a foible of Flight Radar 24, which we all know is a bit of fun but not really relevant to the detail

I wasn’t referring to FR24…

But maybe someone familiar with Mode S transponders can clarify the bit about whether the pressure altitude (delivered to the TXP via gray code or arinc429) is always radiated, regardless of anything the pilot configures.

Anyway, that is digressing from FLARM. The usefulness of that seems to depend on where you fly and how low you fly, etc.

Peter wrote:

But maybe someone familiar with Mode S transponders can clarify the bit about whether the pressure altitude (delivered to the TXP via gray code or arinc429) is always radiated, regardless of anything the pilot configures.

The pilot can disable pressure altitude transmission using the mode switch on the transponder. (I assume you have a mode S transponder so you should have that option.) This is necessary to prevent incorrect information from being transmitted in case there is a fault in the altitude reporting.

But the altitude reporting in mode S is completely distinct from mode C. A FLARM-type device that only receives mode S signals (there is at least one such device on the market) will get altitude information just fine.

FLARM is made by and for glider pilots. It’s usefulness has probably proved itself thousands of times. GA pilots don’t generally fly close together, they don’t compete in large gaggles with dusens of gliders in a single thermal. In a crowded circuit I guess FLARM could be useful, but then everybody should have it.

My current main aircraft (RAF Grob 115E) has Sandel SN3500 EHSI displaying Avidyne TAS600 and FLARM. I’m truly staggered how much situational awareness this combination gives compared to other training platforms I instruct on. However, as proved by an incident last week (idiot other aircraft uninvited trying to tail chase me) if the other aircraft has no transponder (or more likely it turned off) and no FLARM, it was back to ATC on a traffic service to alert me.

I reported an Airprox a few months ago..subsequently investigated and reported : Two planes flying in loose formation approached me (and me them of course) under the London TMA where everyone flies at altitudes of around 2,000 feet, give or take. I saw the first plane some distance away to my left. The second one I saw the underside of as it went over me by something less than 200 feet…I think much less. (The stored radar traces don’t have sufficient resolution to give an exact distance but I can describe the underside of that plane’s wing.)

Not wishing to die earlier than my current age I did some investigation into see and avoid / TCAS / PCAS etc and spoke at length to the Airprox investigator. I was flying with a Zaon XRX device at the time which saw the first plane. It didn’t see the second until it rather filled my windscreen. It turns out that the “person” (I usually use a different term when recounting this story) in charge of the second plane was flying in loose formation, in crowded restricted airspace, without a transponder fitted, so nothing except eyeballs would have seen him. I get high blood pressure just thinking about his recklessness…and you’ll appreciate of course that he didn’t see me until very very late…closing speed of more than 230mph.

Anyway, the chap I spoke to at the Airprox unit likes the Powerflarm device. He explained its benefits and I bought one, and stopped using the Zaon. The Powerflarm is both much better and a little worse than the Zaon.

Benefits of Powerflarm:

• It sees much more traffic than the Zaon : ADSB, Flarm, and Transponder traffic. The Zaon only sees transponder traffic.
• It shows the position of Flarm and ADSB traffic brilliantly. I now actually see the gliders and ADSB traffic out the window, from my cockpit. I don’t just get a beep.
• The Powerflarm however does not show position for transponder-only traffic, whereas the Zaon XRX device allegedly did so within about 45 degrees….but in fact I never found the Zaon to be very accurate and much of the traffic that it allegedly detected I could not see from the cockpit.
• Both the Powerflarm and the Zaon devices can connect to my Garmin Aera 795. In the case of the Powerflarm, for Flarm and ADSB traffic I get a perfect picture of where the traffic is and I can then see it out the window of the plane. It’s incredible. Little planes appear on the 795’s screen showing relative height, direction, direction of travel etc. Very clever.
• The Powerflarm is not great with transponder-only traffic. It just shows relative distance and relative height but no direction information at all. The height is computed from the other plane’s broadcast mode-C height information which may be a hundred feet or so out of course, but that’s close enough. There is no azimuth information which is a pain especially in the circuit where it’s most important… although some pilots say that’s exactly what you want: when the device beeps, LOOK OUT THE WINDOW! I think that’s probably right.

When I was flying in Holland and Germany a few months ago I was amazed and delighted by how well the Powerflarm saw all the gliders. It really provided a good step up in terms of security.

Ideally, I’d like to use my Powerflarm for glider detection together with an installed, certified Avidyne TCAS device detecting transponder and ADSB traffic and displaying them on my plane’s GNS530W, but that is such an expensive installation without currently, a huge uplift in functionality. I can’t quite justify the cost, until we’re all forced to fly with ADSB out when all traffic will appear on screen… including those planes flown by people who currently think it’s clever to fly in crowded airspace without even a transponder…

That’s my tuppence.

Howard