Airbus: Cat III Single or Cat III Dual... what's the difference?

[FlyKingfisher]

Originally posted in Spectators Balcony (Spotters Corner), I was told to try here by Talkdownman:

FlyKingfisher:I believe that pilots flying Airbuses use Cat III Single (Autopilot1 engaged) while flying in good weather and visibility, but Cat III Dual (Autopilot1 & 2 engaged) is deployed only in poor weather and visibility conditions. I read somewhere that deploying both autopilots on an Airbus engages 'Autoland'. What exactly is Autoland and how does a Cat III Single landing differ from a Cat III Dual landing? Any Airbus pilots here?

Talkdownman:Probably not in Spectators Balcony (Spotters Corner) Forum! This is much too difficult for spectators and spotters! Why not try Flight Deck Forums? You might find some Airbus pilots there...

FYI: I'm not a pilot, just a simmer and an aviation enthusiast and I have a lot questions to ask :uhoh:

[potkettleblack]

Thats incorrect and you were given some duff information about the relationship between autopilots and the status of the a.c. The aircraft can be Cat 3 single for any number of reasons. Similarly it can still remain Cat 3 Dual with certain system failures. Whilst the serviceability of the autopilots has some bearing on the status of the aircraft it does not exclusively dictate this.

Further, even if I was flying a Cat 1 ILS on a nice summers day and my intention was to hand fly the final stages of the approach I would engage BOTH auto pilots initially. They would be disconnected later on. This provides redundancy in case one drops out. Flying through a localiser at an airport where there are simultaneous parallel approaches cos you only armed 1 auto pilot and it dropped out could be fatal.

PS: I fly the A320 series.

[FlyKingfisher]

@potkettleblack: I read that in a manual on how to use a certain Airbus payware panel for MS FS2004. Probably used only in a simulator, but not in a real aircraft...

By Cat I ILS, do you mean a 'localiser only' approach?

[potkettleblack]

Nope by Cat 1 ILS I mean an ILS down to cat 1 minimums which are usually around 200ft above ground level.

If you want to do some background reading on airbus systems then go to smarkcockpit.com. Click on one of the Airbus types and there are various system descriptions and even extracts from the FCOM's that you can read to your hearts delight.

[FlyKingfisher]

@potkettleblack: Thanks for the info, and your time :)