Yeah Martin I know what you mean. Funnily enough I was thinking of the same thing when planning a nav flight just before you posted about this.

Anyway, its nice to have an idea of what to say when you're in doubt of your clearance... theres nothing that i hate more than my finger hovering over the ptt button wondering how to word a question!

Dave

For example the text books would say that you can fly at 2100ft without clearance if CAS is from ground to 2000ft, however, good manners would suggest that you still look for a clearance

Actually, no, they have no authority to issue a clearance in that case :)

It's good manners to call them up because (Brize Norton is a classic case, where I have flown many times overhead) they often have traffic about in the overlaying Class G, and they may indeed like to direct you about a bit.

It's one of those bizzare things. You could overfly Brize at 3600ft, non-radio, non-transponder, and I guess they have to assume you are above their airspace.

Primary radar can determine altitude. Is this information not included in civil displays?.

What rubbish! No it can't - that's what Secondary radar (SSR) is there for.

The only primary radar that can detect altitide are purpose built height finders (conventional radars put on their sides) which can give the height on one aircraft (normally) by scanning up and down. They have to be rotated manually in Azimuth to physically point at the aircraft to achieve that.

The only other one is a phased array head such as the Military's PAR (Precision Approach Radar) which again will scan in a limited area only on the final approach.

I am not sure secondary is all that good when the traffic is overhead either - Chilli please correct me if I am wrong.

Depends where the secondary head is.

Not many airfields, civil and military, have their own SSR. Bournemouth does, but it's in the minority. Many civil airports pipe in data from NATS SSR heads. Bristol, Filton, Cardiff? from Clee Hill in Shropshire, East Mids & Humberside from Claxby on the Lincolnshire wolds. Waddington's SSR is at Scampton, Cranwell & Coningsby at Cranwell. So, although you may be overhead the airfield, you may not be in the SSR overhead (which will be a blindspot).

Chilli

Thanks for the clarrification.

Southend came to mind when I made the comment who usually say they cant see you in the overhead so I assume theirs is not pipe fed.

Is it the case that if it is a LARS unit the head is at the unit, or do some rely on piped in radar information?

Hmmm. yeees, not entirely sure where I was coming from there Chilli :\

HWD - never mind, we all have brainstorm days!

Fuji - The primary radar head will always be on the airfield, it's just the secondary that's often "offset". The only variation is the likes of Thames radar, LTCC at West Drayton, plus the centres at Swanwick and Prestwick who use remote heads around the country.

Thanks Chilli.

- sorry for the thread drift.

Just continuing the thread Drift, Cardiff has it's own SSR but also uses Clee Hill on it's long range planning display. We do lose SSR in the overhead with Cardiff SSR as it is based on the airfield but we have dispensation to use Clee Hill in the overhead for our en route traffic.

Actually, no, they have no authority to issue a clearance in that case

IO540, I agree with what your saying. We don't ask for clearance but rather let them know that we'll be crossing at 2100 ft.

I'm assuming then that when you ask for a zone tranist the reply is always
"G-XXXX cleared to transit zone not above 2000 feet" that this is because the CAS is only up to 2000 feet and that they have no control above this altitude??

The issue about cleared to ender CAS in different countries is interesting and practices vary.

In the US, to enter Class C and D two way radio contact only needs to be established (use of each others call signs). The word "cleared" is not necessary. However to enter class B a positive clearance is needed.

It seems to me that the UK operates class D like the US operate class B.

I dont know what the Irish rules are re class C or the French rules re Class D

It seems to me that the UK operates class D like the US operate class B

I think all of Europe does that, but different countries/units work it differently strictly.

No idea which one is departing from ICAO, but it's a bit academic.

The way I was taught is if there is any doubt, check! Airspace violations can be very serious. There is no harm asking if you are cleared to enter any airspace just before entering it.