A320 Cat 3 Status

[Haroon]

http://www.outzeal.com/misc/a320-cat3.jpg

[EGPFlyer]

They are not contradictory. If you set up for a Cat IIIB (dual) approach and you get a downgrade to cat III single then you go around. If you can't then fix what caused the downgrade then you can fly a cat IIIA (single) approach, providing you have the required minima etc.

There's absolutely nothing wrong with flying a cat III single approach on one autopilot (e.g. If the other was Inop at dispatch or had failed inflight prior to your FAF/1000')

[Haroon]

If you can't then ... you can fly a cat IIIA (single) approach, providing you have the required minima etc.

That's what I wanted to confirm, that if you can manage to set up for Cat 3 A well in time, then there is no need for a go around.

(one autopilot) .. had failed inflight prior to your FAF/1000'

Any restrictions if it fails after FAF/1000'? The status will still be CAT 3 Single right?

Thanks a lot.

[Zaphod Beblebrox]

Failure after FAF / 1000' would require that the MCDU minimums be reset from a 100ft alert height to a 50ft DH, (at our company), and that the Captain be fully briefed on the visibility requirement for CATIIIa and the new DH. There is a visibility change as the CATIIIB, or Airbus CATIII Dual, allows for auto-land with a reported visibility at minimums, however the flying pilot, (CAPT) does not have to actually see the runway environment. CATIIIa requires a reported visibility minimum AND the pilot must have the required runway environment in sight at the DH.

Because our flight operations manual is very strict on pilot roles on approach below 1000, our operations certificate does not allow this change if it cannot be accomplished below 1000'. It's not that it can't be done it's that many operators specifications don't allow it.

The FED's, both US and EURO, are picky about what you are allowed to do in a CAT 11 /111 environment. Going heads down at low altitude, and messing with the settings on the approach guidance during very low visibility approaches is not generally a good idea.

[EGPFlyer]

Cheers, I should have added that the FAF/1000 limit is operator dependant.

[EGPFlyer]

It depends on what approach you were flying.. if it's a cat IIIA approach but with cat III dual displayed (2 autopilots engaged), failure of one of those autopilots won't change your ability to fly your planned approach so you could, in my opinion, continue.

[CaptainMongo]

We are authorized to brief one approach only. I.e. we may not brief an approach and a back up approach.

If required we may re - brief an approach until 1500' AGL or the FAF which ever occurs first. After that point we are required to execute a missed approach and start over if we can not fly the briefed approach.

[Haroon]

oh ok got it! its one of those do's and dont's things below 1000 feet.

thank you all.

[Too_tired]

Question seems to already have been answered. But I'd like to chip in:

Keep it simple. There are 3 cases.

Case 1) failure above 1000'. 3 options. 1) fix it 2) can't fix it, so brief to new minima due downgrade or 3) go around/discontinue approach

Case 2) failure below 1000'. Go around for 5 things. Continue for everything else. Things to go around for: i) master caution ii) engine failure iii) alpha floor activation iv) loss of auto pilot (cavalry charge) and v) system downgrade leading to triple click.

Case 3) failure after alert height. Only go around if autolandnlight illuninates*

*always exceptions.

This procedure is clearly operator specific but I believe it's very close to Airbus philosophy.

[CaptainMongo]

Too tired,

I like your K.I.S.S. matrix, where would you put in winds going out of limits? Let's say they are just in limits at the start of the approach.

[EGPFlyer]

It depends when they give you a wind check.. if they gave me one just below 1000' and it was outside of limits then I'd consider continuing down to say 2-300' and ask for another.. if it's still out of limits then go around, if it's within limits then continue (and don't ask for another!)

[EMIT]

Too tired,

I like your K.I.S.S. matrix, where would you put in winds going out of limits? Let's say they are just in limits at the start of the approach.

Must be a strange airfield - RVR just above 75 m ( why else Cat 3b needed) and still the wind going out of limits?

For the OP, many times when LOVIS procedures are used, the WX actually isn't all that bad. Sure, your Cat3 dual allows 75m RVR, but if actual conditions are 200 m RVR, a downgrade to Cat3 Single is no problem at all. If the cause for the downgrade does not really require any more action than turning one knob one click, then that should not be too difficult, even below 1.000 ft. Until when? Well, that would be a nice point to ponder for a captain, who is the PF anyway during LOVIS. Of course, all this has been evaluated and briefed beforehand.

[Too_tired]

Emit, this can happen quite a lot. More a case of when an airfield has a high elevation. You're more 'in cloud' than in fog. Especially when the airfield is on a ridge. The uk had two notorious examples...answers on a post card.

Again, I keep it simple. Wind limits for the autoland are exactly that. They are in the limitations section of the FCOM. Therefor, if the wind is out of limits - don't perform autoland. Simples. When or where you make that decision is up to the commander.

[EGPFlyer]

Bristol, Leeds, Jersey, Luton... more than 2

[Dave Clarke Fife]

Yup..... Jersey. That land of 40kt fog

[EMIT]

Yeah, I was thinking about RAF Brawdy, the 40 kt fog airfield, but there you don't have a low limits ILS.
About the other British (civilian airfields) OK, point taken.

[FlightDetent]

@EMIT should not be too difficult, even below 1.000 ft. Until when? Well, that would be a nice point to ponder Agreed, yet the answer is right there: 1000 ft. No technical reason in particular but the line needs to be drawn somewhere, exactly as you noted.