PDA

View Full Version : Autopilot


320p
15th Aug 2011, 10:36
Hi,
One of our pilot on A320 was recently checked for disconnecting Auto-pilot below DA while doing a CAT I approach.As per the FCOM,on A320, if CAT 2 or CAT 3 is not displayed on the FMA,minimum height to use A/P is 160 ft AGL.Therefore, my understanding is that A/P can be disonnected below DA in a CAT I approach,but by 160 ft AGL.
Any views please?

Avenger
15th Aug 2011, 10:47
Correct 160 AGL for disconnection, unless autoland

rudderrudderrat
15th Aug 2011, 10:48
Hi 320p,

You are correct. In minimum visibility (CAT 1 550m), it is recommended to leave the AP engaged until 160ft agl whilst you acquire better visual references.

Microburst2002
15th Aug 2011, 16:32
If everything was OK and he was flying on AP, he had at least CAT 3 SINGLE on the FMA.
And yet... Can we said that he was doing a CAT II approach without autolanding, where the 80 ft apply?

If he exceeded the limitation (CAT 1 displayed) and the QAR betrayed him disconnecting below 160 ft then he is screwed.

If CAT 1 was not displayed, then he did not exceed a limitation, as such. 80 ft could be taken as the limit, probably.

BlackandBrown
15th Aug 2011, 17:00
Microburst is good!

Avenger
17th Aug 2011, 12:06
For single autopilot operation there will be no flare function and the aircraft would just fly into the ground, hence need to disconnect at 160 AGL and fly manual flight.

Meikleour
17th Aug 2011, 13:49
Avenger: Are you sure about that - because the A320 can do a single autopilot autoland!

NOLAND3
17th Aug 2011, 14:02
Nope, aircraft will still flare on 1 AP

Avenger
17th Aug 2011, 14:46
Yes, I agree the A 320 will autoland on 1 Autopilot... but the original post stated " Cat 2 or 3 " not displayed on FMA:rolleyes:

mcdhu
17th Aug 2011, 17:42
As long as at least 1 AP is engaged and 'LAND' is annunciated, it will autoland.

It might not be pretty though!!

ChristiaanJ
17th Aug 2011, 17:54
As long as at least 1 AP is engaged and 'LAND' is annunciated, it will autoland.OK, I should stay out of this discussion.
But on Concorde (a nice supersonic bird, not a flying coke can) the 'LAND' annunciation meant : one working A/P and accessories, plus a 'hot' spare synchronised and ready to take over.

If the 'bus trusts a single AP to 'autoland' the aircraft, I start to worry.

Can you confirm this?

CJ

BlackandBrown
17th Aug 2011, 18:28
Yes the airbus will autoland with one autopilot. It'll be cat 3 single ( cat 3 a) at best. Cat 3 dual (cat 3 b with no dh) requires 2 aps.

scorpilot
19th Aug 2011, 20:42
The 160' is a limitation but the operator/company would not want you to continue below your "minimums" /mda with the a/p engaged on a CAT I approach...thats my take.

Microburst2002
20th Aug 2011, 09:45
Everytime the 320 makes an autoland with AP 1+2 it is in fact carrying out the autoland with AP1, which is "master". AP2 is only there to take over in case AP1 gets u/s (fail operational). With one AP only, autoland is carried out exactly in the same manner, only you don't have any backup so that if AP gets u/s then the airplane cannot autoland, obviously. But in the bus they guarantee that the airplane will not be out of trim after the only AP tripping (fail pasive).

I don't know if concorde had this fail pasive feature. What a shame that it was decomissioned. It didn't even left any supersonic offspring...

Bus Driver Man
20th Aug 2011, 13:17
If the 'bus trusts a single AP to 'autoland' the aircraft, I start to worry.

Can you confirm this?

CJ
On Airbus (320 and later, don't know for the 300/310), only a CAT IIIB autoland requires 2 AP's.

CAT IIIA and CAT II autoland only require 1 AP.
However, if you have 2 working AP's, procedure requires to engage both of them, even if you are not planning for a CAT IIIB autoland.
Even for a CAT I approach with manual landing, when the AP is still engaged, you should engage both AP's.

And even with an engine failure, Airbus is still CAT IIIA

The bus can also autoland on a CAT I runway as long as:
-The company has checked the ILS beam quality and the effect of terrain
-Wx is CAT I or above
-CAT I minima are used
-At least CAT II is displayed on the FMA

320p
20th Aug 2011, 14:50
"Limitations vs Procedures
The 160' is a limitation but the operator/company would not want you to continue below your "minimums" /mda with the a/p engaged on a CAT I approach...thats my take"

This is interesting!! Just want to know if it is an accepted thought process in present day aircraft and operators? Would others give their view pl.

ChristiaanJ
20th Aug 2011, 15:10
I don't know if concorde had this fail pasive feature. What a shame that it was decomissioned. It didn't even left any supersonic offspring...In a way, it did leave subsonic 'offspring', because much of the system archiecture on the 'buses can be traced back to Concorde.
This was certainly true for the analogue A300, and the more I read about the A320 and families (digital), the more it looks as if they inherited most of the same philosophy.
Concorde used the same 'fail passive' and same 'fail operational' and 'standby synchronised hot spare' features.
And of course Concorde was 'fly-by-wire' too, in the literal sense, even if the formal term was "electrical signalling" ("commandes de vol électriques"), and used a stick and yoke, not a side-stick.
Full 'mechanical' back-up (rods and cables) unlike the limited mechanical backup on the digital 'buses.
And the side-stick was first tried on... yes, a Concorde.

CJ

Bus Driver Man
20th Aug 2011, 17:09
"Limitations vs Procedures
The 160' is a limitation but the operator/company would not want you to continue below your "minimums" /mda with the a/p engaged on a CAT I approach...thats my take"

This is interesting!! Just want to know if it is an accepted thought process in present day aircraft and operators? Would others give their view pl.

I remember flying a CAT I approach with Wx very close to the minima. Ceiling about 200' and very bad visibility due to rain. (I remember only seeing some approach and runway lights)

It was a CAT IIIB rwy, but LVP were not yet in progress. Ofcourse this means that CAT III Dual will be indicated on the FMA when both AP's are on.
During my briefing, the captain (TRI/Training Manager) reminded me of the fact that I could leave the AP on until 80' at the latest.


So no restriction from my company to leave the AP on below minima, as long as we follow the Airbus limitations.