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Okavango
31st Oct 2008, 12:48
Hi. Hope for a little help as this is confusing me. My understanding of Special VFR for a new PPL (with no IMC or IR) is that it is only useful for entering Class A CTR's? Thom's book makes reference to Special VFR providing concessions in poor weather for Class D airspace, though as minma for entry to Class D is less than that for Special VFR (eg 10km vis for a basic PPL), when else is a new PPL going to need it?

Second point is crossing the base of airways for the same PPL. Obviously it's good practice to request crossing the base of an airway, though how far below is this considered to be required (say up to 1000ft below?) to 1. necessitate clearance request and 2. have to cross at right angles. It prompts the question, why would someone want to get so close to the base?

Fuji Abound
31st Oct 2008, 13:37
I can think of only three reasons a SVFR clearance is of use to a VFR pilot:

1. Flight in a class A CTR,
2. Night in a CZ with a night rating,
3. Flight in class D where weather dictates flying between 500 and 1,000 foot over a built up area, but you are still going to need 10K viz and be able to land clear.

Otherwise it will just cause inconvenience for all concerned.

If you are below the base of an airway you are not under any obligation to give notifcation, be it 100 feet or a 1,000 feet. However if close to the base (within 500 feet) a call is courteous if for no other reason than it tells the appropriate you agency you know you are where you are and are not about to do anything stupid. It is exactly the same if you are passing under an IAP. Pilots often do this in open FIR with complete disregard for the controller working the aircraft above. Give the controller a call and at least he can be "assured" you arent some muppet about to pop up into his airspace and cause him a bad day.

bookworm
31st Oct 2008, 14:45
Second point is crossing the base of airways for the same PPL. Obviously it's good practice to request crossing the base of an airway, though how far below is this considered to be required (say up to 1000ft below?) to 1. necessitate clearance request and 2. have to cross at right angles. It prompts the question, why would someone want to get so close to the base?

You're thinking of:

UK AIP ENR 1.1

4.1.6.1.1 Aircraft may, without ATC clearance, fly at right angles across the base of an en-route section of an Airway where the lower limit is defined as a Flight Level.

4.1.6.1.2 Powered aircraft may cross an Airway in VMC by day without compliance with the full IFR requirements in relation to the aircraft equipment provided that the pilot holds a valid Instrument Rating and that clearance is obtained from the appropriate ACC.

4.1.6.1.1 is daft as, VFR at least, you're either above or below the base of the airway, not at it. It will soon be amended, though there's some discussion as to whether the base level is controlled airspace or not. 4.1.6.1.2 applies above the base level.

bookworm
31st Oct 2008, 14:48
However if close to the base (within 500 feet) a call is courteous if for no other reason than it tells the appropriate you agency you know you are where you are and are not about to do anything stupid.

I would suggest that's impractical Fuji. Airway frequencies are typically quite congested, and I don't think controllers want to hear from aircraft that intend to remain below. Even for crossing the airway, the AIP notes that the request should be made on London Info.

IO540
31st Oct 2008, 14:55
Isn't it an ICAO rule that where two airspace classes join, the precise area comprising the join is governed by the less restrictive of the two airspace classes?

Therefore, if the UK complied with ICAO, the base of an airway would be (generally) Class G ? Making this whole subject moot.

Okavango
31st Oct 2008, 15:19
Thanks - confirmed to me what I thought and I don't understand why it needs to be so ambiguous. Strange. Regarding airspace, in my view you're either in or out,and a PPL with no IR shouldn't be in any Airway anyway, so why anyone would skim along the base is beyond me. There should be more practical guidance in terms of how far below you should be before you need not concern the relevant controller rather than instructing to fly at right angles across the base etc.

Fuji Abound
31st Oct 2008, 16:04
I would suggest that's impractical Fuji. Airway frequencies are typically quite congested, and I don't think controllers want to hear from aircraft that intend to remain below. Even for crossing the airway, the AIP notes that the request should be made on London Info.

Bookworm

Doesnt that depend.

For example there is every reason why you might want to cross just below N864 (FL65) (between Exeter and Bristol). You can also expect the crossing to be offered through the airway. Bristol will handle the request. Personally I will often go west between 65 and 100 and as much of the rest of the route is OCAS without a FP, either VFR or IFR the airway is a pain. If you are with Exeter they will arrange the crossing or if you are too far north they will ask you to give Bristol a call. If you are 500 feet below the base and not receiving any service at all a call cant do any harm - albeit perhaps in reality the controllers have very little interest in hearing from you.

Another is example is that wretched R41 (FL35). Plenty of traffic nipping under neath some of which lets Solent know and some of which doesnt bother. Personally I always give Solent a call,although once again I wonder whether they are interested.

I can think of a number of other low level airways where there is every reason why en route traffic might be at a similiar level and want to cross.

IO540
31st Oct 2008, 16:12
a PPL with no IR shouldn't be in any Airway anywayNot quite correct.

A pilot with no IR cannot fly IFR in Class A.

He also cannot fly VFR in Class A unless the Class A goes all the way to the ground (and then he needs an SVFR clearance).

An "airway" doesn't mean anything by itself. Many airways in Europe are not in Class A. This is a peculiarity in the UK, mostly. Most European ones are Class C, and in France they are Class E (below FL110) where you can fly VFR without any clearance.

bookworm
31st Oct 2008, 20:48
Doesnt that depend.

Fair enough.

For example there is every reason why you might want to cross just below N864 (FL65) (between Exeter and Bristol). You can also expect the crossing to be offered through the airway. Bristol will handle the request.

I don't have a chart to hand but isn't that class D belonging to Bristol for the most part though?

"An area of N864, below FL105, between a line joining
513946N 0032432W - 513838N 0031727W -
513743N 0030845W and EXMOR is Class D airspace"

Calling a regional CTA approach/radar frequency who expects to have to integrate VFR/IFR and traffic OCAS is a bit different from calling a London Control frequency.