circling vor/dme

[stancioiu]

Hello!
I have already posted this thread on Tech Log forum so I apologize to those who already read it.
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.
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.
Brgds

[foghorn]

The difference between any circling approach and a straight in approach is that in the circling approach, the final approach track will not be suitably aligned with the runway (+-15 degrees from memory). Therefore visual maneouvring in the vicinity of the aerodrome is required to land.

This means a much larger obstacle area that a straight in approach, which therefore has a knock-on effect on the minima. As its alternative name suggests, the circling portion is visual maneuvring, which takes place after the instrument approach is completed. Technically it's not an IFR visual approach as ATC would understand it - however that's a technicality that it's best not exploring:ok: .

[DFC]

A straight in approach is an approach where the final approach track is within 30deg of the runway centerline.

If the final approach track is not within the 30deg limit then the aircraft will have to manoeuvre to line up with the landing runway.

This requires a larger area to be considered for obstacle clearance.

The most common reason for a circling approach is an airfield where the navigation aids allow an approach to one runway but the wind requires landing on another. In that case, the approach is flown down to the circling minima and once visual, the aircraft is flown level to line up with the other runway.

Regards,

DFC

[stancioiu]

DFC, I know what is a circling approach, but what I was talking about was circling vor approach. If you follow the link from the first post you will see that this is a procedure where you land on the same runway where you execute the instrument procedure, so what is the meaning of "circling"? And the old procedure looked very similar but it was called only vor/dme approach.
?????????
Regards

[Scott Voigt]

I think that you might be confusing it with a DME arc... That is not a circling approach...

regards

Scott

[frac]

Being only a Candian Private Pilot I could be wrong but I think that is is considered a circling approach according to PANS-OPS (DOC 8168).

According PANS-OPS Section 4 Chapter 1, this is the definition of a circling approach:


1.2.3.3 Circling approach
A circling approach will be specified in those cases where terrain or other constraints cause the fnial approach track alignment or descent gradient to fall outside the criteria for a straight-in approach. The final approach track of a circling approach procedure is in most cases aligned to pass over some portion of the usable landing surface of the aerodrome.

I beleive that the approach is considered a circling approach based only the descent gradient. The MAP of runway 08 is at 0.2 DME from the runway threshold. Based on a TCH of 50 feet, it seems that if a CAT C aircraft spots the runway at the MAPT, a descent grandient of 102% is required to cross the threshold at the required height. It is roughly 5170 feet per nautical mile (a bit excessive close to the ground in marginal weather in my opinion).

The circling in the title I believe is there to inform the pilot that it is a circling approach only (no straight in minima). According to PANS-OPS, the procedure should be named VOR/DME A.

Regards,

Marc-Olivier

[foghorn]

It's quite common for the MAPt for non-precision approaches to be over the airfield itself, that doesn't necessarily make them circling approaches.

However I'm damned if I can work out why this is a circling apporach.

For those that haven't looked at the charts, it's a single runway airport with what looks like a perfectly good VOR/DME straight-in approach for each end, which for some reason are defined on the plates as circling approaches, with only circling minima given.

[DFC]

I also can not see an obvious reason why no straight in minima are published.

It could be lack of an obstacle survey or an out of date close in survey and they simply use the circling minima derived from the ILS procedure to get round the problem.

The AIP similarly only publishes circling minima and there is nothing in the notes for the aerodrome to explain.

It could also be that while the aerodrome is H24, ATS is not available for a period during the night and met observations reduce to hourly during the same period. Many countries limit operators to circling minima when not ATS or when QNH is not easily available at the landing aerodrome.

Regards,

DFC

[bookworm]

As I noted on the thread on Tech Log, the Romanian AIP plate suggests that the straight-in minima have been "withdrawn". New obstacle, perhaps? Or someone spotted a flaw in the procedure design?