And how many accidents have happened at that point, compared to collisions in the circuit and simple VFR-VFR entrout collisions?
All very good points… rather sobering too!
Airborne_Again wrote:
According to Timothy there has been zero collisions in IMC in uncontrolled airspace in Britain since the second world war.
I don’t think I have specified Britain.
Can anyone point me to a collision in IMC in uncontrolled airspace anywhere in Europe, or anywhere in the world for that matter? I do have to say after WWII because there wasn’t really controlled airspace any earlier, and there was a mail aircraft going London to Paris which collided with something in cloud in the 1930s.
And I do limit it to civilian aircraft. There have been a few military collisions, like two Javelins in the Morecombe Bay area in the 50s, but they have all either been in formation or on a mission to intercept one another.
This isn’t really a competition, though. The whole point doesn’t get lost because someone finds that a Dove collided with a Sundowner in Croatia in 1952. The point is that if I asked anyone on this forum to name a collision between two GA aircraft in VMC they would immediately give me ten examples off the top of their heads, but we will struggle to find one example in IMC in seventy years.
And yet people are scared of flying without radar in IMC. It’s utterly bonkers. You should be much more scared of flying in VMC without conspicuity and traffic.
On a slight tangent, can anyone tell me the difference between TAS and TCAS I? Apart from cost, I am struggling to find a specification of the difference.
Thanks for asking Timothy – also curious about this :)
Timothy wrote:
On a slight tangent, can anyone tell me the difference between TAS and TCAS I? Apart from cost, I am struggling to find a specification of the difference.
I think they are different frrom a certification point of view but functionally the same. I don’t know if there are different rules on diversity antennas etc. It is TCAS II that introduces RAs which is very different.
Various past threads; this one explains what the Resolution Advisory is.
The most dangerous place is breaking out of the cloud from above and you have a VFR traffic travelling under the ceiling right in front of you…..
I don’t think so because almost nobody (in GA activity terms) flies in or through cloud 
Also, as stated already, IMHO all “IFR” or “IFR capable” pilots are using Mode C/S diligently, and are not interested in hiding anything. I have almost never seen a plane flying in these circumstances (e.g. coming out of IMC, or flying VMC on top) which didn’t show on my TCAS. But below the cloud this happens all the time, with perhaps 1/3 of traffic below 2000ft being invisible, and looking at the aircraft types it is obvious this is deliberate.
That is one of the reasons why flying VMC on top is rather nice
I always thought the difference was TCAS gives you a resolution, TAS only an alert – obviously that may be wrong. Whenever I have flown with TAS it is just an alert.
Only TCAS II gives resolution, as Jason just said.
TAS and TCAS I appear on the surface to give you the same thing, but you can, for example, buy the GTS 800 (TAS) for much less than the 855 (TCAS I), so there is clearly a difference, I was just idly wondering what that difference is.
