CAT 3 b no DH on A 320/330
Joined: May 2000
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From: Camp X-Ray
What more explanation do you need? You need dual channel autpilot redundancy for Cat 3B No DH, if the machine says you are Cat 3A Single you don't have it so you can't do it. Some things cannot be explained more simply.
Joined: Sep 2002
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From: La Belle Province
I would suspect that the reason you can't do a CATIIIB approach with a failure case - which is what I think that message is telling you, that you're down to a single channel system, no redundancy - is that IIIB requires a fail-operational status i.e. that everything keeps working after a failure. Obviously if you're on a single-string system it can't be fail-operational.
Suppose your single system goes offline below the IIIA DH, and you're operating as per IIIB rules. You aren't assured of the GA, but have no assured landing either. To avoid that problem, you have to respect IIIA rules.
Caveat: supposition, not knowledge of the Airbus system.
Suppose your single system goes offline below the IIIA DH, and you're operating as per IIIB rules. You aren't assured of the GA, but have no assured landing either. To avoid that problem, you have to respect IIIA rules.
Caveat: supposition, not knowledge of the Airbus system.
Joined: Feb 2005
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From: Correr es mi destino por no llevar papel
Originally Posted by vikena
suppose your status page says CAT 3 single only.
Can you do a CAT 3 B no DH approach?
(...)
yes I know what the FCOM says.
Can you do a CAT 3 B no DH approach?
(...)
yes I know what the FCOM says.
Mad(flt)Scientist gave you a very good answer - it's a certification requirement, independent of airplane type/manufacturer. In order to be IIIb qualified you have to have working fail-operational system and that's what FMA tells you: CAT3 SINGLE = fail-passive, CAT3 DUAL = fail-operational.
Now I'm curious; were you asked this question by someone who wouldn't take "It's a limitation, for a
's sake!" as an answer?
Joined: Aug 2007
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From: local
Gents
Everybody is correct in some form or another, basically it is fail operational so if you get redundacy on finals you can go around or land depending on the downgrade.It is a certification issue for the relevant authorities. At the end of the day you can autoland CAT 3 NO DH with CAT 3 Single.
The a/c only knows the ILS and the course and Flare mode, it will continue to land whatever the limits, do not forget only YOU know the RVR unless Airbus have made the a/c that clever.
Imagine you are low on fuel or some emergency!! What you going to do put it on final and autoland whatever the wx or DH is. All be it NOT legal!!!
Just my small input, so please no bunfight!!
elac2
Everybody is correct in some form or another, basically it is fail operational so if you get redundacy on finals you can go around or land depending on the downgrade.It is a certification issue for the relevant authorities. At the end of the day you can autoland CAT 3 NO DH with CAT 3 Single.
The a/c only knows the ILS and the course and Flare mode, it will continue to land whatever the limits, do not forget only YOU know the RVR unless Airbus have made the a/c that clever.
Imagine you are low on fuel or some emergency!! What you going to do put it on final and autoland whatever the wx or DH is. All be it NOT legal!!!
Just my small input, so please no bunfight!!
elac2
Thread Starter
Joined: Oct 2005
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From: hkg
hand solo,
You will find that most limitations have an an explanation, and if you believe and accept limitations without question you are probably a sort of a dork.
Others , thank you for your time and contributions,
V
You will find that most limitations have an an explanation, and if you believe and accept limitations without question you are probably a sort of a dork.
Others , thank you for your time and contributions,
V
PPRuNe supporter
Joined: Dec 2003
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From: Planet Earth
Vikena, not trying to start anything here but in reference to an explanation, your original question was very weak, they clearly answered the question you put forth so get over it.
Joined: Feb 2005
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From: Correr es mi destino por no llevar papel
Originally Posted by vikena
if you believe and accept limitations without question you are probably a sort of a dork
Let me uncover some aspects of it for you.
As a professional pilot, you can believe and accept limitations without question and no, it won't make you a sort of dork. Probably or improbably.
As a professional pilot, you can believe and accept limitations, while questioning them.
But not believing the limitations, not knowing or not accepting them is not an option, ever. There is exemption to that if you think that limitations are set too high - you can set your own more conservative ones but more liberal - no way.
And why is that?
Because there were hundreds of very smart and skillfull people who designed the aeroplane. They have made some very long and complex calculations and came out with some numbers and said:"We think that our airplane is capable of performing this". Then there were very smart, very brave and very skillfull people named test pilots and flight test engineers. They have taken a look at calculations and said "It looks right, let's check it out in the air." And they went out test flying. Sometimes they returned to report everything worked out OK. Sometimes they returned to report that some improvements are needed. And occasionaly they did not return. Anyway, after the test programme was completed, up came the smart people of the certifying authority and said: "What a wonderful airplane you have! And it performs so very well! But, you know, it will age, airframe will get weaker and not all the pilots who will ever fly it will be as god as your test pilots. So let's add some safety margins; 5 percent here, 20% there..." So many excellent people worked hard for years and results are summed in a couple of short sentences like:
MTOW 64 000 kg
Vmo 350 KIAS
CAT IIIB operations allowed with CAT3 DUAL displayed only.
And you think you are smarter than all those people and that their limitations do not apply to you?
Think again.
At the end of the day you can autoland CAT 3 NO DH with CAT 3 Single.
Yes, you can autoland A320 in zero visibility, using CAT I only ILS but you are not allowed to! Why? Because there were a hundreds of experts, who took the time, calculated the risks and said: "Nope, it's not acceptable - you have to have a lot of ground and airborne equipment operative and trained and current crew too to bring down the risks of low vis landing to acceptable level." Have you ever done actual CAT II or III landing? Gentlemen, actual CAT III makes my heart race faster than practising engine failures at take-off in a simulator. And someone uninformed, sitting at jumpseat could easily say "Now this was very easy for you. You did nothing except shouting "ONE THOUSAND" and "ALERT HEIGHT". Yeah, right.
Granted, busting the limitations and minima is preferable to running out of fuel above the sea of fog. But rest assured that all the circumstances of the incident will be closely scrutinized and expect no mercy from your company or licensing authority if they discover that you spent your alternate fuel in the holding. But it is always better to be debriefed on your shortcomings, to the tune of your licence going through the document shredder, than to have the whole world read about them in an accident report.
Joined: Jan 2001
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From: home
If you have Cat 3 DUAL in inop sys on status page then try...FCOM 4 irregularities!
If "CAT 3 DUAL" is displayed in INOP SYS without any other failure being detected :
CHANGE the AP in command. It may allow the CAT 3 DUAL function to be recovered.
If this procedure fails :
SET FAC 1 pushbutton to OFF, and back to ON
WAIT for FAC 1 fault ECAM warning to disappear, and
APPLY the same sequence for FAC 2.
CHANGE the AP in command. It may allow the CAT 3 DUAL function to be recovered.
If this procedure fails :
SET FAC 1 pushbutton to OFF, and back to ON
WAIT for FAC 1 fault ECAM warning to disappear, and
APPLY the same sequence for FAC 2.
Joined: Mar 2000
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From: Arizona USA
You will find that most limitations have an an explanation, and if you believe and accept limitations without question you are probably a sort of a dork.
Maybe...but OTOH, I have known a few pilots who disregarded said limitations, and are now rather fatally dead...explainations, or no.
