ANY installed transponder must be turned ON

I’ve seen in various places the CAA saying they prefer ADS-B over the proliferation, as ADS-B is a standard, it’s very very cheap to receive, and it integrates with transponders.

The problem is that the UK sites are full of uncertified ADS-B type products, none of which show up on certified ADS-B IN. They show up only on tablet displays, which limits adoption severely.

I don’t think airliners see any ADS-B targets; they see only Mode C/S.

A literal interpretation would indicate that mode A meets the stated requirement.

That’s a big missed opportunity to stop the Mode A crowd from taking the p1ss. Of course the inability to legally install a Mode C (except when replacing the same model unit) plays towards this situation, because the “civil liberties” (and various other motivations for now showing the registration) guys don’t want Mode S.

I don’t get the same interpretation from the document quoted which is not the law any way.
But the CAA doesn’t have the means to enforce that part of SERA so it is going to stay a good practice rather than a requirement

Peter wrote:

Does anyone know whether the SERA reg requiring all installed transponders to be ON is complied with by the following

Mode C or Mode S unit, set with ALT=OFF i.e. appearing as Mode A only

Mode C or Mode S unit with the altitude encoder (or its connection) broken, appearing as Mode A only

Ref. SERA.13010(a)

That sounds quite useful for those who want to fly Mode A.

Yesterday in Mig alley near Bovingdon traffic service called several 2-3 mile targets ‘altitude unknown’, presumably mode ‘A’ or off. When seen visually these turned out to be certified aircraft which are surely xpndr equipped. So (presumably) the instructor had turned it off to avoid trouble in London’s ludicrously complex and restrictive airspace. Or renters had learned from instructors to do the same.

Surely any aircraft doing this should be followed up for a spot of re-education, or the mad airspace should be fixed so instructors don’t fear for their livelihoods on every flight.

At the same time, any ATC in this area claiming ‘too busy’ for a traffic service should be the subject of an MOR.

Peter wrote:

The problem is that the UK sites are full of uncertified ADS-B type products, none of which show up on certified ADS-B IN. They show up only on tablet displays, which limits adoption severely.

It’s the opposite – if they had to be certified, due to the high costs, it would limit adoption severely. Hardly any piston SEP/MEP has a certified traffic display (you are an exception in this case). On the other hand at least 80% of pilots fly with tablets, and many have some kind of mount for phablet/tablet devices. For example, a recent beach fly-in I went to, about half the three axis microlights had some kind of low-cost ADS-B IN receiver and a tablet mount permanently attached to the panel. Low prices and tablet usage encourages not “severely limits” adoption. Requiring expensive certified panel mount displays on the other hand would severely limit adoption. I wouldn’t bother with ADS-B at all with my transponder upgrade if it couldn’t show on low cost devices. However, seeing how many aircraft, including aircraft worth less than £10k are now receiving ADS-B IN using a low cost receiver and tablet has meant that my basic requirement for the transponder upgrade is that it shall from day 1 have ADS-B OUT.

It’s pretty irrelevant for the certified displays, since you’ll see the Mode-C or Mode-S transponder, and don’t need the ADS-B to be able to display it. Low cost devices do need the ADS-B.

Also, right now it’s actually impossible (legally) for an LAA aircraft to squit certified ADS-B. Even if you have certified gear installed IAW the TSO, the maximum SIL level you can emit is 0 (or 1 for a TABS device – AUIU certified displays need SIL=3,SDA=2) because the LAA don’t yet have the knowledge to authorise anything more than that. (However the LAA plans to perform more investigation on this before the year is out with the intention of allowing SIL=3,SDA=2 for TSO’d position sources.)

Interesting… What would make most sense would be an illegal way of emitting sil 3 cheaply We did this before… The garmin waas data stream is under an NDA.

However

Hardly any piston SEP/MEP has a certified traffic display

Most modern ones do have it. And all bizjets. Arguably these are the biggest risk / at the biggest risk.

Peter wrote:

Most modern ones do have it. And all bizjets. Arguably these are the biggest risk / at the biggest risk.

But both bizjets and expensive modern SEPs can see transponders, so whether the transponder is squitting certified or uncertified ADS-B is not important as the bizjet TCAS will see the Mode-C or Mode-S transponder. Also, bizjets spend most of their time in CAS.

So if you have a transponder that can squit ADS-B, it’s still worthwhile squitting uncertified ADS-B, because now all the lower end stuff (which outnumbers modern high end SEPs by about 20:1) will now be able to see where you are as opposed to just seeing your level. Of course if you can use certified ADS-B that’s probably preferable but it won’t make any material difference since the high end stuff could see your bare transponder anyway, and the low end stuff will display your ADS-B position regardless of SIL/SDA.

Peter wrote:

Interesting… What would make most sense would be an illegal way of emitting sil 3 cheaply We did this before… The garmin waas data stream is under an NDA.

If you’re using a Garmin GTX335/345, you just set the SIL of the position source through the transponder’s configuration menu. (Unfortunately much to my chagrin, Garmin transponders that I otherwise really like won’t take an uncertified NMEA position source, it either has to be ARINC or Garmin’s proprietary stuff. Trig et al. will take NMEA for uncertified ADS-B out).

Can anyone give the definitive word on non-Waas 430 as a position source? Some say even SIL=0 is illegal, others not. (TT21 transponder). It’s a simple cable and lots of certified GA have similar setups.

Thanks

Alioth – I don’t disagree, and it’s a good point about active TAS/TCAS being happy with just a Mode C target, but if you speak to bizjet pilots they will generally tell you that the scariest bit of their flight is the bit in Class G, and like airliners they generally don’t have ADS-B IN, and if they did have it it would show only certified ADS-B OUT anyway (but any mod like that on a bizjet is so expensive (tens of k plus) that you just don’t do avionics upgrades on a bizjet just for a laugh). So targets which are non-TXP or Mode A are their biggest problem regardless of what else they radiate. And this applies to the higher end of GA also; although that end can install mods for “just” single digit thousands, most of them don’t use tablet traffic displays because they don’t want that in a busy cockpit especially as the audio warning coupling is an extra complication.

So SIL=0 etc is not visible to the “fast” traffic unless you are also radiating Mode C/S, but a lot of the customers for the low end ADS-B OUT products are likely to take advantage of this to fly as non-TXP or as Mode A, while radiating SIL=0 and thinking everyone can see them. You can’t blame them because it is a lot cheaper than spending 1000 quid on fixing an altitude encoder. Plus a lot of them are avoiding Mode S because of the aircraft reg radiation and this being readily visible to ATC.

I also think that tablet displays of traffic is a poor solution because in most cases the user will not have an audible warning, due to the various complications. It’s like car satnav without audible speed camera warning.

The GTX345 has or can have its own WAAS GPS so it can emit SIL=3 ADS-B OUT, AIUI.