A few things have got me thinking about systems that can show other traffic based on transponder/FLARM etc.
My requirements are this: it must be effective and it must be portable. There is absolutely no option for a permanent mount since we just don’t have the panel space – we don’t have panel space for a radio nor a transponder hence our radio is up on the roof and the transponder is jabbing the passenger in the knee. This is just life with an antique aircraft that was flying before having a radio was a common thing.
In another thread, MooneyDriver mentioned PowerFLARM which looks like it fits the bill. It also has the added benefit of our glider club’s glider also being FLARM equipped, but the PowerFLARM also receives Mode C and Mode S signals (I have to presume it’s a passive system looking for other aircraft’s replies to interrogations).
Who has experience with these types of devices? How effective are they likely to be in the UK where I keep hearing about transponder equipped aircraft being flown with the transponder switched off (I don’t know any pilots who do this, so I’m not sure it’s a real problem).
Well yesterday west of Gloucester we had multiple transponding aircraft within a few miles of us similar altitudes and saw prob 20%. So I don’t think it is a big problem. In your situation a portable option makes sense but I have no experience of the powerFlarm.
PowerFLARM is great. I bought it right when it was first released and I use it in a Cessna and hardly ever have traffic that it doesn’t display. When on a long IFR flight, it allows for plane spotting by showing the ADS-B targets. It has helped me several times in airprox glider situations. I live in the middle of a very active glider region. I considered a TAS to be too expensive and not helping with the gliders.
PowerFLARM is not only passive. As I understand it, other FLARM participants (e.g. gliders with FLARM) also receive the data packages my own transmitter sends
PowerFLARM ® receives position and movement information from the integrated GPS receiver. In addition, an integrated pressure sensor improves the position measurement. The predicted flight path is calculated and is sent at one-second intervals through its low-power radio as a short digital message – including its unique identification code. Almost simultaneously, these messages are received by other FLARM ® – or PowerFLARM ® devices, aircraft with ADS-B or Mode C and Mode S transponders in the area and is compared to their projected flight path.
from
http://powerflarm.aero/index.php/en/technology/warning-technology
I had the Powerflarm before TCAS. It works amazingly well with anything ads-b, and gliders. With mode C aircraft, it’s more or less like the small Zaon, I.e. quite imperfect. I have lent my unit to several people and none has offered to buy it.
Powerflarm is probably a cost effective way to get ADS-B IN.
But who radiates ADS-B?
I told Powerflarm that if they could do azimuth on Mode C targets they would have a totally market beating product, but they are completely uninterested. Unfortunately, something like 99% (my average across the UK and Europe) of “technologically detectable” traffic is Mode A/C/S only. And the rest (which in the UK is about 50% of the traffic you will meet at your local Class G airfield circuit, or is found shooting through the IAP platform in a Class G airfield) radiates nothing.
radiates nothing.
Heat, possibly, so you might try an IR camera 
Actually, I wonder how the drones are supposed to avoid traffic. They must be loaded with all the obvious gear but how do you detect a C150 with no radio emissions? Side-on, the IR signature can’t be much.
Somebody in the UK was trying to detect strobes. Apparently this works well even in daylight, using the rapid risetime of the pulse.
Peter as a matter of interest, as you mention “drones”, at a meeting with the RAF recently a very senior office, who is Station Commander from where UAVs are operated, was asked about UAVs in UK airspace whereupon it was categorically denied that they operate anywhere in UK airspace. The questioner then pointed out that could not be true because NOTAMs are issued to that effect for an area in South Wales which is still UK airspace. The denial was restated and the officer left immediately. The following day the MOD admitted that USA operated UAVs had been allowed to transit UK airspace at high level.
Who is one to believe these days?
But who radiates ADS-B?
I do. The Trigg TT31 can, if connected with a compatible GPS, in my case a GNS430. Quite a few S transponders are capable of that and those which are should be connected.
So with Power Flarm I got the warnings for ADS-B, Flarm and Mode C (altitude only), while I transmit ADS-B for others to see. (Yes, my plane can be seen on flight radar 24 at times too, but I can live with that).
Those who are not, radiate mode C. In PF you see them as a circle and altitude, so you know that someone is at the same altitude or near and from the signal strenght you can roughly estimate how far away. What that does for me is, the moment a circle pops up I start intensified surveillance and almost every time I get him with a few seconds. That does NOT mean I do not watch out all the time, but I would intensify my normal scan if there is a contact.
Trouble in the Mooney is that I do not have a sufficient glareshield space to mount the PF properly, so what will happen during my upgrade in fall is that it gets panel mounted. For FLARM especcially it is vital that the antenna can be straight up, which it is not at the moment due to the glareshield problem. ADS-B and Mode C are not affected by this however.
I can fully recommend PF. For me, it is the best solution for renters (portable) and for others who can not or don’t want to go all the way with a full TCAS solution, which in many cases won’t show the all important gliders anyhow.
In Switzerland, all air rescue helos and quite a few military ones are by now equipped with either Flarm or Power Flarm. Inexpensive to do but highly effective.
