Well now I'll try a second time to post my reply. The first time I tried to reply, the system accused me of not being logged in - and, of course, I then couldn't get back to what I'd written!
Wonder if a ModBod can find out what happened there?
keithl... always a pleasure to help a colleague!
reynoldsno1... I've heard a suggestion that the small circling radii were considered to be a contributory factor in that nasty prang in Colorado some years ago. The way I heard it, the FAA made some slight changes to enlarge circling areas, as a result of that finding and that at least some folks in the FAA think the circling radii need to be the same as Pans Ops. Time will tell though, I guess.
Ojuka... your right about it being unwise to commence the turn prior to the lead radial. Pans Ops requires us to provide a lead radial/bearing that equates to a 2 NM turn radius and there is no requirement to protect an earlier turn. It seems to me that your only option is to select a speed that will keep your turn radius within the 2 NM provided by the procedure.
In PNG, we don't have a problem with turn radius for this manoeuvre because we impose an overall speed limit of 170 knots on Cat A/B for Initial Approach and 200 knots for Cat C/D. This invariably means that, in zero wind, the turn radius of every aircraft is comfortably within the turn radius limits.
I would've thought that, in other parts of the world, there would be a duty of care to make some sort of regulatory comment about speed in that turn, if there's no speed limit on the chart or in the rules.
Personally, I make the turn at 170 knots in the B200 and this almost always results in a turn radius of 1.5 NM. I do some simple maths to derive a lead radial that equates to 1.5 NM, instead of the 2 NM and this almost always works out spot on.
This might not be totally suitable in your area of operations, if you regularly experience strong winds. We don't usually have a major problem with that and, even if we do, it's more likely to be a headwind than a tailwind, so it's not as critical to the turn. However, it should give you a basis for experimentation - in good wx of course!
