circling vor dme approach

[stancioiu]

Hello!
Can someone explain what is the difference between a vor/dme approach and a circling vor/dme approach, excepting the higher minimums? May I revert anytime to a visual approach in case I have the runway in sight in a circle vor/dme approach? I couldn't find any reference in PANS-OPS.
Brgds

[flyboyike]

Are you in contact with ATC or are you flying the approach "own navigation"?

[Spitoon]

stancioiu, I think we need some more information. From the ATC perspective it's not just a choice between ATC and own navigation. If you are flying a procedural approach you are, by definition, on your own navigation - the answer about changing to a visual approach depends on the air traffic service (if any) that you are receiving. If you are under ATC, you would need to be cleared for a visual approach because ATC still have to separate you from other IFR aircraft.

As to the type of approach, is the difference that the VOR/DME approaches a runway but the circling bit relates to visual manoeuvring following an IAP to a different runway (or a cloudbreak procedure, correctly called an aerodrome approach procedure I think).

Sorry if this is all known to you but I offer it just in case it helps.

[stancioiu]

If you have acces to Jeppesen Eastern Europe, the chart I refer to is 13-1 at LRCL/CLJ CIRCLING VOR/DME Rwy 08. Or you can try here: http://ivao.flightsim.ro/getpage.php?page=charts at LRCL. I know how to fly a circling approach, but this is a circling vor/dme approach where you fly the instrument procedure for the same runway you are supposed to land. You can find circling vor approaches also at LFSB and at LGSM.
Brgds

[stancioiu]

Forget about LFSB it's somehow a conventional circling. My mistake!

[bookworm]

A couple of interesting things from the Romanian plate. The approaches are described as VOR/DME (next line) Circling rather than Jepp's "Circling VOR/DME". It also notes on the plate that the straight-in procedure has been withdrawn.

Some conventional IAPs don't satisfy the criteria for having straight-in minima. This is usually because of descent gradient or alignment of final approach track (neither of which appear relevant here). Thus only circling minima are published, in accordance with the obstacle clearance requirements for Visual Manoeuvring (Circling), even though, in many or most operational situations, aircraft will not need to manoeuvre on the approach.

Perhaps one of our IAP experts could suggest why straight-in minima can't be published for this one?

[BizJetJock]

Looking at the plate, two possible answers come to mind.
The less likely one is that from the MAP you have 0.2 miles to lose 674 or 1084 feet depending on category, making an impractical descent angle; however since they also publish advisory heights for a 3 degree approach I think this is unlikely.
A more likely reason is the fact, that is not terribly obvious from the profile, that the VOR is actually 5 miles beyond the runway. Therefore the "cone" of possible position at MAP is probably too wide for a straight in approach to be guaranteed, so they have assumed that you will have to do a circle to line up with the runway.
It is very easy in these days of FMS/GPS overlay approaches to forget just how "non-precision" the traditional aids are!