@Alpha_Floor wrote:- One of few UK deviations I actually agree with since they make more sense than SERA/ICAO.
This is where I would totally disagree with you.
Yes most VFR takes place below 3000ft, but I see no good reason to change the rules above that, especially if the only thing against is that its a nuisance.
Alpha_Floor wrote:
I don’t think I have ever encountered other VFR traffic when flying above 3000 ft AGL. If there is someone up there, it’s mostly IFR, and in that case you’re in Class E or above receiving traffic information.
That does not reflect my own experience. Over time, I have had a sufficiently high number of close encounters (me and my girlfriend: “WOW – where did THAT come from?”) and a countless numbers of “visuals/no factor” to take the topic seriously. Incidentally, I think the critical ones were above 3000 ft AGL.
Ibra wrote:
Hard to say without any real data or simulations but it surely depends on traffic density, airspace size and speed deltas
Good point!
I intuitively believe the risk is mitigated by allowing and encouraging VFRs to fly at random levels.
Take the segment between 3,000 and 10,500 ft. If you stick to the SERA levels there are only 4 levels available per direction of flight, maybe only 3 depending on transition layer. If you bin this rule and encourage random levels, there are 60-65 levels available (depending on the TA/TRL).
Also, my experience when having other VFR traffic appear “out of nowhere”, is mostly when both are flying in roughly similar directions on converging tracks (for example, both flying to the same VRP/VOR/town/feature etc, because they pop up from the side rather than from the front where one naturally tends to look more often. In this scenario both converging VFRs may well be flying on the same “correct” SERA level.
When I fly following a line feature, particularly a coast line, I always fly at non-obvious levels and I feel this is the safer thing to do. So if the SERA level is 3500 I would fly at 3200 or 3700 but not bang on 3500.
My personal opinion is that this whole thing makes all the sense in the world for IFR traffic but very little sense for VFR…
So if the SERA level is 3500 I would fly at 3200 or 3700 but not bang on 3500.
It will be very hard for the other pilots to spot you.
Alpha_Floor wrote:
Take the segment between 3,000 and 10,500 ft. If you stick to the SERA levals there are only 4 levels available per direction of flight. If you bin this rule and encourage random levels, there are 75 levels available.
There is other traffic as well – in between the VFR levels are the IFR ones.
Patrick wrote:
Over time, I have had a sufficiently high number of close encounters (me and my girlfriend: “WOW – where did THAT come from?”) and a countless numbers of “visuals/no factor” to take the topic seriously.
Had this discussion many times before: Numbers are quite obvious. There is no more than 1 mid-air in cruise every 10 years in Europe. It is – also due to flight level rules – a rather no issue. It is a much more significant issue in other phases of flight, esp. in airport traffic where due to flight path restrictions the 3Ds of flying are practically collapsed to a 2D or even 1D problem.
If planes fly “randomly” in 3D (i.e.: without any flight path restrictions, waypoints/ nav aids that practically reduce degrees of freedom, etc.) it is (almost) a thousand times more likely to have near miss by 10m (which is really close!) than an actual accident. A 100m near miss (not really near for a glider pilot but many less involved observers do perceive this as close) is more than 100.000 more likely than a hit. So as long as your “high numbers” do not go into the 10ths of thousands, it is still far away from a “random” midair…
Malibuflyer wrote:
There is other traffic as well – in between the VFR levels are the IFR ones.
Sure but when that’s the case you’re (mostly) in Class E and above. In CAS this whole thing doesn’t apply because you’ll request a cruising level to ATC and they will either approve it or not.
Class E would be a special case because VFR can operate without being in radio contact with the ATS unit controlling IFRs. I think most VFR pilots flying in Class E will be in contact with ATC even if they are not required to.
We could consider VFR and IFR mixing in Class G, but where in Europe is this a common thing other than in the UK? And oddly enough, the UK doesn’t make this whole thing mandatory, they recommend random levels.
skydriller wrote:
I have found that when I am cruising above 3000ft VFR “going somewhere” and I choose and relay to the FIS controller (Europe) that I am at FL45/55/65 etc, then half the time they reply confirming the FL and half the time they reply with a comparable altitude with QNH…
Were you at/below or above the transition altitude at the time? The semicircular rule doesn’t say whether you should use flight levels or QNH. E.g. in Germany the TA is typically 5000’, so FL45 would not be ok for a westbound flight but 4500’ would be.
Alpha_Floor wrote:
One of few UK deviations I actually agree with since they make more sense than SERA/ICAO.
It’s not really a deviation since SERA permits that individual countries prescribe other levels. (See the quote in your first post.)
Malibuflyer wrote:
If planes fly “randomly” in 3D (i.e.: without any flight path restrictions, waypoints/ nav aids that practically reduce degrees of freedom, etc.) it is (almost) a thousand times more likely to have near miss by 10m (which is really close!) than an actual accident. A 100m near miss (not really near for a glider pilot but many less involved observers do perceive this as close) is more than 100.000 more likely than a hit. So as long as your “high numbers” do not go into the 10ths of thousands, it is still far away from a “random” midair…
That is a fair point and brings this into an objective, statistical perspective. But frankly, there is a subjective element to this as well – for those flying along even more so.
It really depends on what assumption you make about the effectivess of vision.
A target on a genuine collision course will be a stationary point in the sky, and very hard to see until the last few seconds.
Statistically therefore one is much safer flying at random levels.
But this goes against the grain of widely taught and “therefore accepted” wisdom in aviation 
Also many people, and most non-aviation people, find it emotionally very hard to accept that vision is almost ineffective. Their disbelief is generally cured by flying in a TCAS equipped aircraft
I have not seen VFR levels enforced or even suggested except in France, IIRC, where an ATCO made some oblique suggestion, to me requesting say FL070, like “then you will be looking for FL075” or some such. Similarly to IFR semicircular levels which are generally disregarded in CAS, except IIRC in Belgium and Italy.
In the UK, I just tell them I am at 3300ft or whatever and nobody questions it.
