Hi,

I can't seem to find where in the AIP, the rules regarding VFR navigation tolerances when operating near CTA/Restricted areas without a clearance are. On page 135 of the bob tait CPL air law book, it says the reference is AIP ENR 1.1 para 19.11 - but i'm guessing the AIP reference has changed as that paragraph is now titled "GPS - Operations without RAIM".

In AIP ENR 1.1 para 19.6.2 however, numbers are given for Aircraft deviations in controlled airspace - advise to ATC. Are these numbers the same as the tolerance applied when operating near the boundary of CTA? Or is there another reference i should be looking at for that? It says half-scale deflection of the CDI for VOR, +- 5 degrees for NDB, but doesn't give the numbers for navigating by visual reference or DR as in the bob tait book. Also, the numbers for NDB and VOR are different in the book - the book says 6.9 degree for using NDB and 5.2 degrees for VOR.

Thanks

If you check that AIP reference in the current AIP you will find that it simply says that you must not enter CTA without a clearance and if you do not intend to ask for a clearance, then you should make sure that you do not enter CTA. This is surely a breath of fresh air when it comes to common sense. I find it difficult to believe that anyone in CASA came up with this unassisted!

All of that old rubbish about so many degrees here and there was always a load of BS and nobody I have ever met ever took any notice of it. In fact, nobody I have ever met even knows anybody who ever took it seriously - pilots simply avoided CTA if they didn't have a clearance. The kind of person who did fly into CTA without a clearance certainly would not have bothered to read it in the first place. Could this be the dawning of a new age for CASA?

Thanks Bob. Maybe worth updating the book - I was using the ebook, which should be the latest version already?

The numbers in the old rule seemed somewhat arbitrary anyway - It seems more practical to leave it up to some common sense and proper flight planning (what's available in terms of position fixing, and how accurate it will be).

Interestingly, I just got a question on this in my air law exam. It asked for a number of a degree value of tolerance to be applied to avoid CTA when using VOR.

I have seen somewhere that tolerances are closer the lower down you are, seemed to remember recommended spacing from CTA to avoid penetration.
The GPS is good it warns you SUA ahead and then at 2 MILES.
And under stress of weather anything goes as I heard the other day on FSU it was either bullets or lightning,
The pilot choose the weather avoidance track over the live firing range and they quickly suspended live firing for him so the story goes.