Originally Posted by radar707
Having worked Class E airspace in the UK I have to say it is awful, a known / unknown environment providing a Radar Control Service to IFR traffic and having to avoid unknown VFR traffic (with every legitimate right to be there),
This is a good example of how UK ATC occasionally seems to 'upgrade' controlled airspace and thereby remove the flexibility that should be available in the 'lower' classes of CAS such as D and E. I suspect that similar mis-application of IFR-VFR separation criteria in Class D zones is what makes life so difficult for GA pilots trying to get across some CTZs and sets much of the UK airspace user community against the introduction of CAS. It would be simpler if such zones were defined as Class B - at least it would make the position clear to everyone!
ICAO does
not mandate the provision of separation between IFR and VFR traffic in Class E airspace. In Class E one can assume that all 'unknown' contacts must be in VMC, and hence ICAO considers that safety is maintained purely by the passing of traffic information. In contrast, while providing a Deconfliction Service to IFR traffic in Class G (which is what happens in the approach patterns at numerous UK airports), one has to assume that all 'unknown' contacts are in IMC and CAP774 says you will provide (advisory) vectors against them. This is actually a significant escalation in ATC workload against baseline ICAO, as you would not be
legally required to provide such vectors even in Class D airspace!
In Class E airspace, ATC is accountable only for IFR-IFR separation, and is required to provide traffic information only as far as is practicable. The legal difference between this situation and the extant ATSOCAS in Class G is the transfer of collision avoidance responsibility from pilots to ATC
in the specific case of 2 participating IFR aircraft. If one of the aircraft is non-participating then a collision would (in raw legal terms) be a failure of see-and-avoid in VMC, or negligent failure to obtain IFR clearance by the non-participating aircraft. So despite concerns about resourcing, the practical effect of Class E in legal terms is merely to force ATC to take ultimate responsibility for deconflicting its
participating IFR traffic. I don't see that as particularly unreasonable.
If the CAA considered that provision of traffic information (alone) for IFR-VFR conflictions in Classes D and E is sub-optimal in view of the limitations of 'see and avoid', it could apply a national difference to ICAO that says something to the effect 'where practicable, IFR traffic will receive advisory deconfliction vectors against unknown or VFR contacts'. This would have the same legal and practical result as Deconfliction Service in Class G, but the core of the service provision would align with ICAO and be much more readily understood by the international user community.
Originally Posted by radar707
I'd rather have Class D with a higher base for my IFR or Class G with the relevant service I am ABLE to provide at that time.
As indicated above, in Class E you are only mandated to separate your participating IFR traffic. If you become saturated with this task, how exactly would the ability to downgrade the service (which is what I think you like about Class G) help matters? The only benefit I can think of is that it removes responsibility for the ensuing potential collision from ATC, which in turn allows the beancounters to get away with under-resourcing, all the while allowing the buck to stop with the pilot!
Anybody who has ever been involved in any International working group to develop standards such as ICAO, ISO or ITU will tell you that the one thing theses standards aren't is "best".
Yes, but that doesn't mean that they should be ignored. National procedures should build upon the international standards as a common baseline, even where the end result is somewhat divergent. A good example is how the US tweaks the ICAO requirements for VFR clearances in classes C and D, which in a few lines of AIP text brings them to a position where they can implement extensive CAS without significantly impeding VFR operations, whilst providing total clarity for the IFR pilot. Meanwhile, instead of making minor tweaks to ICAO airspace classes to suit national requirements, the UK defines swathes of Class G and then applies quasi-ICAO restrictions or recommendations (useful get-out clause, that) in the AIP. Why have this:
Originally Posted by UK AIP GEN 3 3.5.2
The more aircraft that are known to Approach Control at an aerodrome outside Controlled Airspace, the better will be the service provided and pilots are therefore strongly recommended either:
(a) To avoid flying under IFR within 10 nm radius at less than 3000 ft above an aerodrome having Approach Control; or
(b) if it is necessary to fly under IFR in such an airspace, to contact Approach Control when at least 10 minutes flying time
away and to comply with any instructions they may give.
when you could simply define a 10nm/3000' Class E zone - which would be eminently understandable to all familiar with ICAO, and would be complied with even by those foreign pilots who had not read the AIP from cover to cover
!
Before someone brings up ICAO's statement that Class E is not to be used for aerodrome control zones - I struggle with the logic that moves from that position and then builds a control zone in Class G by applying quasi-Class D rules in national legislation (yes, it sounds ridiculous, but that is how we get to the ATZ, isn't it?). How would defining ATZs as Class D airspace actually change daily operations at simple VFR airfields? I am willing to be educated!