[jhb_airlines] Re: SemiCircular

  • From: "Bones" <bones@xxxxxxx>
  • To: <jhb_airlines@xxxxxxxxxxxxx>
  • Date: Thu, 17 Jul 2008 16:21:30 +0100

VFR aircraft are not subject to any mandatory levels. The Quadrantal and
Semicircular rules are for IFR aircraft only but many VFR aircraft comply
with them too. The point is that you can't force a VFR aircraft to fly at
any level except when inside a CTR and even then you cannot allocate a
specific level. 

If you give a VFR aircraft a radar heading to fly or a level to maintain and
he then flies into cloud, loses control and crashes it is your
responsibility and you would be charged with manslaughter. VFR aircraft have
to remain clear of cloud at all times and so a clearance must provide them
with the ability to do so. For this reason an aircraft cleared into the zone
will be given a height band to operate in rather than a level - "JHB777
enter the zone, not above 3000ft on QNH 1021" - the important bit here being
the NOT ABOVE bit as he can freely alter height between 3000ft and sea level
if needed to remain VFR.

If there are other aircraft nearby at say 2000ft and there would be a
confliction if the aircraft had to leave 3000ft then you simply pass traffic
information. There is no requirement to separate VFR aircraft inside a CTR.
Of course, once a pilot has left your zone and is in the FIR he can do what
he wants - your only task then is to warn him of potential conflictions.


-----Original Message-----
From: jhb_airlines-bounce@xxxxxxxxxxxxx
[mailto:jhb_airlines-bounce@xxxxxxxxxxxxx] On Behalf Of F FISHER
Sent: 17 July 2008 09:50
To: jhb_airlines@xxxxxxxxxxxxx
Subject: [jhb_airlines] SemiCircular


My first contact last night,was a C172 at 3500ft VFR EGBE-EGNV, asking for 
overhead transition Leeds.

Which I granted, also pointed out that current route would be MATZ 
penatration Netherthorpe/Leeming. The pilot checked charts and agreed. He 
stayed on frequency for FIS to Durham. I was the only controller in the 

Thinking about afterwards, I dug out and checked the semicircular rule 
chart, and see that for west to east, I should have dropped him down to 
2500, or taken him up to 4500, is that correct?? or which would be correct.

Had not thought about this previously.

Frank F 

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