I believe there is a 3-letter place in the known universe where this is the case, or will be soon,...
AUS?....after Feb 2016 GNSS will be mandatory for IFR...after Feb 2017 ADS-B will be mandatory for all IFR
ADS-B is currently irrelevant, although somebody choosing a Mode S transponder might want to choose it for upgradeability.
Is there one that complies with EASA regulations coming to us this year? I.e. is there a GA transponder that complies with (E)TSO-C166b? I don't know of any one.
To detect motored GA, it triangulates the Mode C/S transponder signal.
AFAIK it doesn't triangulate (how could it, you'd need 3 different positions to receive the same signal), it just uses field strength to approximate distance, same thing a storm scope does with lightning. Which is, um, crude.
they should mandate ADS-B out
Yes but then they shouldn't change the fundamental protocol every 2 years or so. So far we have 3 major versions of ADS-B, and counting.
There’s an interesting research paper from the Massachusetts Institute of Technology on this topic here: Unalerted Air-to-Air Visual Acquisition ( local copy )
24 participating pilots (half of them with a CPL) executed a flight for 45 minutes in a Beech Bonanza. One of their tasks was to keep a lookout for traffic.
At cruising altitude, a Cessna 401 flew by within 500ft separation. Once from head-on, once from behind and once at an angle from the side.
Only 56% of the target traffic was detected. The average “acquisition range” for these 56% was 0.99NM. The greatest range of visual acquisition range was 2.9NM.
The research paper also describes the difficulty of detecting other aircraft on extreme clear days.
Due to the lack of contrast between the visual target and the background, it is more difficult to visually detect other traffic in extremely clear conditions…
[local copy added – Peter]
One of the things we should do is make ourselves more visible in high traffic density environments by making occasional s-turns. That exposes a greater surface of the airplane to other aircraft at the same altitude and create a moving target to others coming dead-on.
And active TAS a is a great tool that saved my bacon at least once when cleared to descend on top of another aircraft at L2K.
After the requirement for a hi viz jacket, perhaps EASA should mandate all aircraft also to be hi viz? Just think of the ranks of yellow or orange aircraft on the apron 
Although, knowing the insight that the typical EASA bureaucrat brings to bear on a problem, they would probably mandate either blue or grey as the required colour!
Neither of us saw the other. I realised at that point that just looking out was next to useless.
Mind you there is looking and there is looking. I often spot traffic even if I haven’t heard them on the radio.
But there is the occasional ‘ghost’ that you know about, but never see. Often they’ll pass well clear, and you’re just looking in the wrong place.
But yes, big sky principle, combined with assisted/radio-enhanced Mk1 eyeball works very well fortunately.
I agree that a lookout, in combination with position calls / traffic advisories over the radio and the big sky principle (statistically separated) works reasonable well.
But it’s an illusion that it is safe just because your seek&avoid skills work so well.
Every pilot with a TCAS system on board knows that there is a lot of traffic around which you will never spot.
I often spot traffic even if I haven’t heard them on the radio.
I also have it the other way around: Sometimes ATC warns me of traffic, and as hard as I (and my passengers) try, we simply never saw the traffic…
Every pilot with a TCAS system on board knows that there is a lot of traffic around which you will never spot.
Around 90% of TCAS targets are never spotted, I would say.
That means a lot more than 90% of aircraft are never spotted – because so many (in the UK, anyway) are non-TXP.
However, a lot of traffic reported by ATC or seen on TCAS is too far away to be spotted. In the UK, a radar service will give you traffic up to 5nm away, but almost nobody will spot that unless the contrast is really good and it is moving the right way. TCAS might show an aircraft up to 10nm+ away (usually more like 2-5nm with light GA targets). This stuff is both almost impossible to spot and there is no point in looking for it because (a) you won’t see it and (b) it doesn’t present a conflict.
What is worrying is how much TCAS traffic which is say 1nm away is never spotted. That % is still very high.
Around 90% of TCAS targets are never spotted, I would say.
I mentioned it before you and you keep mentioning it. I disagree, I spot virtually everything that is on my traffic monitor. At least 80%. I virtually never see traffic with my eyes that is not on the monitor unless I fly very low (e.g. 3000-5000ft).
Does anybody have a similar experience as Peter?
Achim, you probably have the same quality Mk1 Eyeballs as Chuck Yeager and Bud Anderson. That is why they were (almost) never shot down…
