gallois wrote:
So your only alternative would be mandatory ADSB in and out as in the USA.
ADS-B is not mandatory in the USA except in high volume traffic areas, B, C, or above 10000 MSL. So if you remain clear of the B’s and C’s and below 10000 MSL, there isn’t a mandate. Most of the US airspace is below 10000 MSL (2500 AGL). Also the US mandate is only for ADS-B Out. ADS-B In is not mandated.
Stay out of the red or yellow areas in the US and below 10,000 MSL (2500 AGL) and ADS-B is not required, neither is a transponder.
172driver wrote:
isn’t that a moot point in the UK? 90+% of VFR traffic there seems to operate way down around 1000-2000 ft AGL where the rule doesn’t apply anyway.
What tends to happen is that most light GA fly either:
So if you avoid those levels it’s almost impossible to have a mid-air while EN-ROUTE. And as soon as you are on top of clouds there is NO ONE else there.
I once flew with a time-builder who had something like 120 hours or so, when I encouraged him to climb above a layer of FEW/SCT clouds at 3000’ to be on top of it at 5000’ he said he had NEVER EVER flown at “such high altitudes”. And he wouldn’t have done it if it wasn’t me encouraging him. This seems to be the typical mindset.
I’ve had a few near misses, all in the L.A. area – unsurprisingly, given the traffic volume here – and all below 3000ft AGL, where the semi-circular rule doesn’t apply. On two occasions ADS-B saved me, one of them in a manner I doubt I’d be here to write this without it. Above 3000ft AGL you stick to the semi-circular altitudes and nothing bad will happen. In 23 years of flying, much of it x-country, I never came even close to a near miss while en-route.
In any case, isn’t that a moot point in the UK? 90+% of VFR traffic there seems to operate way down around 1000-2000 ft AGL where the rule doesn’t apply anyway.
Fortunately I have only had 2 near misses, both below 3000ft where the semi circular rule did not apply. I saw neither until the last minute, both had given innacurate position reports.
To this day I don’t know, how on each occasion we managed to miss each other.
gallois wrote:
So your only alternative would be mandatory ADSB in and out as in the USA.
Do you think all aircraft owners in Europe will go for that?
The US requirement is ADS-B OUT in the same limited areas where a transponder has long been mandated for most planes. ADS-B IN is not mandatory, but is so easy and inexpensive to buy in non-certified, portable form that it’s widely used.
I’ve been in two situations where head collision looked likely and in both instances I rolled the plane on its side to the right and closed the throttle.
igor wrote:
“When two aircraft are approaching head-on or approximately so, both should yield to the right.”
But what if they’re slightly off to the right (from each other’s perspective)? Is it still a good idea to turn right?
Depends of the rule is to clarify right of way way before getting to danger stages? or what you actually need to do in a head-on imminent collision?
Difference between “right of way” and “imminent collision”, is both pilots are aware of the conflict in the former they should have plenty for time to turn to the right and deconflict as per the rules of the air, for imminent collisions, I don’t think the answer is in ICAO Annex 2, surely one pilot has not spot the other (or none of pilots saw it comming !)
I saw few miss in gliders near o wing span (or I have been told after I landed), I am sure most of the time for an imminent collision one of the pilots is not moving at all, I can’t see how both move the same time? it’s only untill the firs one puts the wings on 90deg where the other can notice it…I doubt the practical problem has a very “very symetric” geometry & timing to question the validity of the right turn on first sight 
igor wrote:
The Rules state… “When two aircraft are approaching head-on or approximately so, both should yield to the right.”
But what if they’re slightly off to the right (from each other’s perspective)? Is it still a good idea to turn right?
I do the same as I do with a yacht.
If it looks like it might become too close for comfort then I make a big, obvious manoeuvre which leaves the other party in no doubt whatsoever as to how I intend to put more distance between us.
So your only alternative would be mandatory ADSB in and out as in the USA.
Do you think all aircraft owners in Europe will go for that?
The semicircular rule is one of these many, many things in aviation that made sense at the time and in the circumstances they were designed for, but do not work in some of the circumstances the actually apply now.
The assumption underlying this rule is that
1. you have IFR / VFR traffic in the same airspace
2. IFR is separated from IFR procedurally or radar control
3. IFR traffic is mostly flying straight lines on ATS routes
4. VFR is separated from VFR by see-and-avoid
5. VFR is separated from IFR by flying +-500 ft from IFR levels.
This works reasonably well en-route in class E and above, and primarily prevents IFR / VFR conflicts. As long as IFR traffic is constrained to the ’000s, and as long as you believe that 500ft VFR/IFR separation en-route is required, there is no real alternative (random levels are not available, and a quadrantal rule would seriously reduce the number of available levels for VFR).
BUT it does NOT work in “free for all Class G airspace” without any air traffic service provision, because only (1) applies, while (2), (3) and (5) are simply not true – here a rule that does not distinguish IFR from VFR, with random altitudes, and/or a quandrantal rule are all objectively better from a separation point of view.
It also has been overtaken by reality, where there is very little IFR en-route traffic at the typical VFR cruising levels, so reserving 50% of the airspace in class E for <1% of the traffic is detrimental to safety.
But hey, were would we be if rules that were designed 60 years ago would be changed for something modern? In the 21st Century? No way, we will need at least another 50 years…
Alpha_Floor wrote:
The truth is that see and avoid does not work very well in practice. But SERA doesn’t care.
Well, we all know that but still everyone relies on it – not least the UK CAA! (I know about the CAA conspicuity initiative, but such equipment is expressly not for collision avoidance but for situational awareness.) An admission that see and avoid doesn’t work means that something else must be put there instead. Somehow I have the feeling that statistical arguments won’t be accepted (although that’s what we are working with in practise).
