GT again

[SOPS]

Can someone else confirm what I think, that CAT3 B is zero zero, our resident aviation expert seems to think differently.

Airport to move on upgrades - The West Australian (http://au.news.yahoo.com/thewest/a/-/wa/18058287/airport-to-move-on-upgrades/)

[le Pingouin]

It's location specific.

YMML RWY 16 ILS CAT IIIb - RVR 75m, no decision height.

http://www.airservicesaustralia.com/aip/pending/dap/MMLII04-134.pdf

"Category IIIB permits a DH below 50 ft and an RVR not less than 50 m"

SKYbrary - Instrument Landing System (ILS) (http://www.skybrary.aero/index.php/Instrument_Landing_System_%28ILS%29)

[sleeve of wizard]

2.2.2 CAT III B DEFINITIONS
ICAO and FAA definition
A category III B approach is a precision approach and landing with no decision height or a decision height lower than 50ft (15m) and a runway visual range less than 700ft (200m), but not less than 150ft (50m).
JAA definition
A category III B approach is a precision approach and landing with no decision height or a decision height lower than 50ft (15m) and a runway visual range less than 700ft (200m), but not less than 250ft (75m).
Notes: ICAO/FAA and JAA differ by the minimum RVR associated with CAT III B approaches (50m / 75m).
JAA: Where the DH and the RVR do not fall in the same Category, the RVR will determine in which Category (CAT III A or B) the operation is to be considered.:cool:

[MakeItHappenCaptain]

Perth Airport uses a CAT 1 instrument landing system in fog. Under the system, pilots must be able to see the runway from a height of 61m with forward visibility of 800m. A CAT 111b system would reduce that height to 15m and forward visibility to 75m.


AIP Gen 2.2 Instrument Runway Definition
Precision approach runway, CAT III. An instrument runway served by ILS to and along the surface of the runway and:
(i) for CAT IIIA - intended for operations with a decision height lower
than 30M (100FT), or no decision height, and a RVR not less than
175M;
(ii) for CAT IIIB - intended for operations with a decision height lower
than 15M (50FT), or no decision height, and a RVR less than
175M, but not less than 50M;
(iii) for CAT IIIC - intended for operations with no decision height and
no RVR limitations.

Nope...can't confirm what you think. Your expert may just be correct.

[By George]

What makes it complicated is individual Airlines seem to have variations in their approvals. My previous company had a CATIIIb minima of 20ft and 100m RVR. Cathy Pacific, I think, are zero ft. Both Companies meet the definition of IIIb.
With a 20ft minima it was not uncommon to touch down during a Go-Around, an odd experience. Once you develop faith in the system it's a real Fog beater and gives you a great sense of protection.
Currency is a downside, we needed 8 a year to remain current, mostly done in the Sim.
I am only CAT I now and feel strangely vulnerable. 200ft and 800m is a nice day. Good to see old Auntie Australia thinking about joining this Century. It will need an environmental study and several committees no doubt, but still great news.

[Anthill]

The short answer is that CAT IIIB allows for RVR down to 75m. On arrival at the minima, it may well be "zero/zero"' Cat 3B means that at least one light associated with the RCL or TDZ would be visible. This may not be the case.

The idea of RVR is a machine measured visibility concept. It has nothing at all to do with how far down the RWY you can see. RVR determination does not use a human observer.If the machine (transmissometer) detects an airborne water droplet density (fog) that equates to a calibrated value of 75m, the aircraft can lawfully continue on approach past the Approach Ban Point (usually the OM or another fix) and land. This is provided that there is no DH associated with the approach.

The actual RVR limitation may be higher than 75m; it depends on what RVR the operator has approval to use on the given RWY. Some CAT 3B approaches do have a DH and well as an RVR minima.

In practical terms, as long as RVR is above the minima, the aircraft can continue on descent past the ABP and land.

Zero/Zero minima is CAT IIIC which is not operationally approved anywhere in the world yet, to my knowledge.

CAT IIIC is a bit like 240 min EDTO, it's there in concept, but nobody has operational approval to use it.

[neville_nobody]

Perth airport are hilarious. A few years ago they put out a draft plan saying there was no need for a third runway and they had it all under control. They didn't need to spend any money on anything and the passenger numbers would just double in about 7 years.

Now they are going to be 'accelerating discussions' which is code for procrastinate some more whilst aircraft are queued up all over the place. Every year or so they put out a puff piece talking about what they might be doing whilst never actually doing anything about it.

It will take a incident/accident before they take some real action.

[Andy_RR]

What's the point of an RVR specification of >50m when you're thundering along in 350 tons of 747 at 150kts. 50m is less than a second, so hardly likely you can do anything about what you see.

What am I missing? :confused:

[Kooka]

What's the point of an RVR specification of >50m when you're thundering along in 350 tons of 747 at 150kts. 50m is less than a second, so hardly likely you can do anything about what you see.

What am I missing?
The minimum vis is so that the aircraft can be taxiied after landing.

[Anthill]

Hi AndyRR,

Are you talking about landing or take-off phase? 350tns is a TO weight for B747. LDG is about 270tns ish.

There are different specifications regarding RVR for TO as opposed LDG.

[Andy_RR]

The minimum vis is so that the aircraft can be taxiied after landing.

That's a fair point Kooka. You can tell I don't fly 747s for a living, Anthill! :}