Airborne_Again wrote:
How come?
Maybe he means that the semicircular rule is North/South in some countries? I know Spain for example changed from West/East to North/South not long ago. (Except for the Canary Islands which remained West/East).
And countries like Chile, surely a West/East rule wouldn’t work there.
Alpha_Floor wrote:
Maybe he means that the semicircular rule is North/South in some countries? I know Spain for example changed from West/East to North/South not long ago. (Except for the Canary Islands which remained West/East).And countries like Chile, surely a West/East rule wouldn’t work there.
Sure – and the Rules of the Air (both ICAO Annex 2 and SERA) permit that. E.g. SERA: “Except where otherwise … specified by the competent authority.…”
Ok let’s look at an example. Say I am tracking 150° in VFR I could fly at fl35, 55,, 75, 95 etc.So say I choose fl 55. If everyone obeys the rules an give or take 100’ ft for altimeter accuracy or not quite setting the exact dash on QNH setting, I then knw that any IFR flight on a magnetic track from 000° to 179° should be either 500’ below me or 500’ above. So I shouldn’t need to worry about them even if I am unintentionally 100’ above and he is 100’ below.
There is also the added advantage that any VFR traffic I am catching up with and which is flying at the same level will be either on the horizon either directly in front of me or to my left. My eyes would only have to raise or drop only a little for those flying up to 100’ above or below.
Of course you do have to expect other VFR traffic coming from behind or from your right will see you. But like you your eyes have less of the sky to cover.
Any VFR or IFR traffic in the opposite track ie 180° to 359° will of course be well seperated by 1000’.
Now lets you decide to fly at any altitude between 3500’ and 5500 ft. Well yes it is a big sky but if there is other traffic where do you expect to see it? Say for instance you decide to fly at 5700’ you are only separated from IFR traffic by 300’ assuming your altimeter isn’t maybe reading 100’ low and the IFR traffic 100’ high in which case your separation is now only 100’.
Now lets say everyone decides on the free for all, as VFR traffic your duty is to see and avoid. You visual sweep has to cover a much larger area of sky.
Hence, “All is ok until it isn’t”
Airborne_Again wrote:
How come?
My example was: flying 4500 ft easterly bound, whereas the recommended cruise altitude easterly bound is either 3500 or 5500.
Since SERA minimum altitude for such recommendation is 3000 ft, wheras e.g. in Germany earlier you could fly any direction below 5000 ft.
The SERA is based on ICAO proposals. The FAA has it, Europe does in most part, and UK does too. For UK see here, page 109, Appendix 3:
So flying exactly in the altitude, where traffic is supposed to fly in opposite direction, seems to me bad airmanship (if there are no reasons to deviate from the recommendation, such as terrain elevation or whatsoever) and thus the wrong altitude to fly.
But it is not true for any place in the world, and we have places in Europe, too, where the recommendation is different. Therefore, the altitude may be correct for one country and a bad idea for another country.
Is your question answered?
Sorry just realised my error, VFR traffic flying 150° would only be separated by 500’ from IFR traffic tracking 300°, but not from IFR traffic going in the same direction. I think everything else is about right. But I am sure others will immediately spot the errors.
UdoR wrote:
recommendation is 3000 f
While I understand your argument, and indeed have much sympathy with it, please don’t mix up the matter by calling it a recommendation. It is not a recommendation (except in the UK). It is a requirement, albeit one often ignored.
Using the wrong terms can lead others to believe it’s just a recommendation, when it isn’t.
Alpha_Floor wrote:
I know Spain for example changed from West/East to North/South not long ago.
Does anyone know why they did that? I haven’t flown in Spain in some years, but it was not the case last time I flew there.
172driver wrote:
Does anyone know why they did that? I haven’t flown in Spain in some years, but it was not the case last time I flew there.
Because most flights within Spain are generally of North/South tracks. There is a lot of traffic transitting through Spain from South America and Europe. Also, the airways in Spain already reflected this anyway, where south-bound airways were odd levels and north-bound airways even levels.
I think that was the reasoning.
In the Canaries, most flights are intra-island hops which are West/East.
dublinpilot wrote:
While I understand your argument, and indeed have much sympathy with it, please don’t mix up the matter by calling it a recommendation. It is not a recommendation (except in the UK). It is a requirement, albeit one often ignored.
Yes indeed. I stand corrected. I interpreted the “shall” in SERA.5005 (g) as non-binding.
(g) Except where otherwise indicated in air traffic control clearances or specified by the competent authority, VFR flights in level cruising flight when operated above 900 m (3 000 ft) from the ground or water, or a higher datum as specified by the competent authority, shall be conducted at a cruising level appropriate to the track as specified in the table of cruising levels in Appendix 3.
The guys of Eurocontrol give this information more strictly (…is required to maintain this altitude, contrary to the situation, e.g., in UK):
However, I still must confess that the way I interpreted it (fly the cruising level, but in an altitude band of some hundred feet) seems wise.
Although there are arguments against it. Altimetry system error is allowed to accumulate to 245 ft of deviation from “real altitude”, according to ICAO doc 9574. So worst case, IFR traffic flying FL60, but real altitude is 245 ft below, and VFR traffic flying FL55, but real altitude is 245ft above, this gets close indeed.
The safest way to fly VFR is at funny numbers like 3700ft and in solid IMC 
