Breakcloud Ndb Approach

[WindSheer]

Hello all,


Can someone explain the reasoning behind a breakcloud NDB approach.
I know not all air fields use them, what would be the criteria and weather conditions etc.

Cheers:ok:

[Dockjock]

In Canada they are still quite common, particularly in the north. They are used as just that- to get below the cloud deck in order to complete the approach visually either by circling or landing straight in.
Why would anybody want to use one? Because an ILS, Localizer, or GPS approach is not available at that airport and its the only way to get in!
Typically minimums are in the 400-500' AGL range but can be as low as 350 in very flat terrain.
Is that what you were asking?

[WindSheer]

DOCKJOCK thanks for your reply.

I have been looking at various plates and couldnt quite work out why most of them are 'side on' approaches, your reply answers why.
Its obviously not used as a final approach method, just a way to become visual.

So, if you descend to say 350 AGL, what happens then if you are at a right angle to the runway. Do you remain visual at that height. turn and land or re-climb and follow a standard NDB approach.

?????

Cheers for your help.

[Pilot Pete]

If it is not a straight in approach you would descend to your circling minima; typically 800 - 1000 AGL and level off to then visually manoeuvre (circle) to land on the active runway, keeping visual at all times and staying within the circling area for your category of aircraft. You would not descend to a 350' minima at right angles to a runway. If you get down to your circling minima and can't see the runway (or lose sight of it whilst circling) then you go around following the missed approach procedure for the instrument approach you flew, which can get quite complicated and needs careful consideration before you fly the approach.

PP

[OzExpat]

In Papua New Guinea, I provide a "Cloudbreak" approach whenever the Missed Approach Point has to be located outside the circling area applicable to the highest category of aircraft that can use the approach. The reason for this is invariably related to obstacles in the vicinity of the aerodrome, or in the missed approach segment.

The chart shows a visual DR leg from the MAPt to the aerodrome, but the pilot is well and truly on his own if he proceeds beyond the MAPt and subsequently looses visual reference. The MDA for the approach takes no account of obstacles along the visual DR leg, or in the circling area - unless they happen to fall within the protection area for the final or missed approach segments.

This type of approach is always a last ditch effort to provide some sort of instrument approach when nothing else works. I've even be known to employ a Cloudbreak for a GPS approach!

And, yes, the AIP describes the Cloudbreak procedure so that pilots understand the limitations that apply to them.

[Tinstaafl]

Windsheer,

There are two main types of approaches:

* Runway (or landing) approaches, and
* Circling approaches.

Runway approaches are those that position the aircraft on final approache, more or less in line with the runway & in a position from which a landing can be made with minimal manoeuvering. The idea is that the pilot becomes visual with the runway straight ahead & in a position from which a landing can be made. Precision approaches such as the ILS are an example of this, as are non-precision approaches such as a VOR/DME runway approach. The non-precision runway approach isn't able to have as low minima as a precision approach due to the greater buffer that must be allowed due to the lesser accuracy but the concept is the same.

Circling approaches, on the other hand, aren't necessarily trying to position the a/c on final and able to land straight ahead. Instead they're only trying to get the pilot visual with the runway at a height safe enough to manoeuvre around the runway & positon for landing. Think of it as becoming visual in the circuit area, rather than positioned on final. They can be arranged that becoming visual in the circuit area also is somewhat aligned with a runway, but don't have to.

Often a runway approach will also have a circling minima published on the same approach chart. This gives makes available two types of approaches using the same navaid. The pilot could do the runway approach with lower minima, or if another runway is more suitable, do the same approach to the higher circling minima then manoeuvre around the aerodrome to position for a landing on another runway.

Years ago the philosophy of 90 deg approaches to the runway for a circling approach was that the pilot would have a good opportunity to sight the runway crossing the nose, cross overhead & sight the windsock then be able to turn L or R onto a downwind for the favoured runway. This sort of thing would be done if a runway approach wasn't able to be provided

Nowdays it's considered the less the manoeuvering the better so most approaches are designed to be runway aligned, where possible.

[QSK?]

What is a "Cloudbreak" NDB approach? I'm not familar with the term.

I thought all instrument approaches were a "Cloudbreak" procedure!

[OzExpat]

You're sort of correct there QSK but the reason for the "Cloudbreak" terminology is to differentiate it from a "Straight-In" (aka runway-aligned) and a "Circling" approach. The essential difference is that the Cloudbreak won't necessarily line you up with anything in the vicinity of the runway.

This is intended as a warning to the pilot that he/she better have an idea of what sort of obstacles exist in the visual DR segment between the MAPt and the final approach alignment for landing. It may not necessarily mean that you'll need "local knowledge", although that is undoubtedly the safest option. But you should at least have studied an appropriate topographic chart of the area to familiarise yourself with potential hazards.

[WindSheer]

Thanks for all your replies, Question answered perfectly :ok:

[Tinstaafl]

Oz used to have a few cloudbreak procedures. No aerodrome associated with the navaid, but an instrument approach that would get you to an MDA so that you could procede VFR if Wx allows.

Bromelton NDB to the S/SW of Brisbane comes to mind.

[QSK?]

Thanks OzExpat:

So would the Yarrowee (nee Melbourne) VOR approach (can't seem to locate the chart on Airservices' online documents) be classed as a "cloudbreak" procedure?

The YWE VOR has an approach procedure but no associated airport. It was purely designed and installed following significant political pressure to allow farmers (most notably one Malcolm Fraser) to get visual so that they could land their aircraft at their local farm ALAs.

[OzExpat]

Yes Tinny and I have an idea that there used to be on in NSW. Can't think where it is, or was, off-hand, but am sure it was somewhere out in the styx.

Don't think I want to comment on the "Malcolm Fraser" aspect QSK :} but the way you describe the approach sounds like you've got the right concept. :ok:

[sanjet]

Remember that you DO NOT do a missed approach right after reaching your minimum alt. For the ndb/non-precision approach, we actually have to stay at that minimum altitude and track inbound until we reach the MAP (missed approach point). To get MAP, we usually have DME if available or simply use our timer when we pass our final approach fix. Once we pass the DME/time, then we follow missed approach procdures. There are time when I flew 400 AGL right above people's houses for like 1-2 minutes waiting to see the runway. Usually gets you close to the field to transition to visual, and you got to act quick.
Real fun!