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CAT IIIB A/P failure question

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CAT IIIB A/P failure question

Old 23rd Oct 2017, 13:52
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CAT IIIB A/P failure question

Afternoon gents,

RVR 75m, autopilot failure when runway (-centreline) in sight....what does your company recommend; G/A or landing?
Regulation does not preclude landing but advises against it as a general rule. Please state a/c type you're working.

Thanks,
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Old 23rd Oct 2017, 15:02
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IIRC, on Airbus airplanes you can continue landing manually if you have sufficient visual reference.
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Old 23rd Oct 2017, 15:35
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We have three independent autopilots. So "autopilot failure"(in the singular form) should have no effect on a 747 or 777.
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Old 23rd Oct 2017, 15:38
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Considering RVR 75m and rwy in sight as stated,for sure you are below 200ft RA,so if AP(s) disconnects you get the AUTOLAND warning light flashing.If at any time you have the autoland light flashing, Go around is the only option according to the books.Unless you have fuel leak or any other very critical malfunction which is again based on airmanship and pilots discretion.To answer the question, in our company,the norm is GA.Obviously,A320 family.
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Old 23rd Oct 2017, 15:45
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Taken straight from Airbus FCOM:

Below 200 ft (Alert Height) for CAT 3 DUAL:
Approach may be continued unless autoland light comes on.
In the case of Autoland warning light:
- Visual references not sufficient:
GO AROUND...................................................... .............................................PERFORM
- Visual references sufficient:
Approach may be continued manually


(My bold)
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Old 23rd Oct 2017, 15:53
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Company (Airbus and Boeing) Ops Manual rule...fail passive.. (Boeing CAT IIIA)...total autopilot failure in the flare visual reference achieved....manual landing specifically mentioned as being allowed if commander thinks manual landing is safest option.....

Fail operational (Boeing CAT 3B, min RVR 75m) ..for a total autopilot failure in the flare aircraft QRH says go around required...but with a caveat that refers back to Ops manual rule stated above.........

(FWIW our latest recurrent check just happens to throw this scenario in, with all the associated noises, as part of the LVOPS renewal section right at the end of a IIIB approach with visual not achieved....oh how we laughed....or not....)
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Old 23rd Oct 2017, 15:59
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Correct, sidestick. But the original poster question was about your company policies not airbus'. So in our company, they seem to prefer the safer option of GA if any case Autoland flashes. At least,so far.
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Old 23rd Oct 2017, 16:12
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Airbus 320Series. The company says:

Any AUTOLAND [AUTOLAND light] warning requires an immediate go-around

If visual references are sufficient and manual landing is possible, the PF may decide to land manually.
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Old 23rd Oct 2017, 23:40
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Originally Posted by Jesse Pinkman
If visual references are sufficient and manual landing is possible, the PF may decide to land manually
Is there any other option?

(sorry -- couldn't resist)
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Old 24th Oct 2017, 00:49
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Originally Posted by AirbusLover
Considering RVR 75m and rwy in sight as stated,for sure you are below 200ft RA...
Not necessarily...

RVR is horizontal visibility at/near ground level. In the case if ice fog or other shallow but thick fog, you may have visibility above Alert Height, and lose it near or on the ground.

In the 744, a go-around is mandatory in Cat III conditions if the LAND 3 reverts to LAND 2 (likely with single A/P failure) or NO AUTOLAND (likely with multiple A/P failure or multiple other failures) above AH. Assuming no other overriding factors, if the visibility on rollout will be less than Cat II RVR minimum, a Go-Around is your best option.
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Old 24th Oct 2017, 14:54
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Interesting question. As is mentioned above, now on the bus we have to go around except if sufficient visual references are available.

On the 737 a downgrade from LAND 3 to LAND 2 meant that we could accept CAT IIIa 50ft RA (CAT IIIa) instead of no DH (CAT IIIb). We always bugged all relevant minina, which is 50ft RA, CAT I minimum (which showed up as a triangle on the altitude band but without callout unless activated by rotating the minima switch). So in a case of downgrade simply press the minima switch, continue to 50ft and decide as usual. In case of a NO AUTOLAND message, re-bug to CAT I and decide there. Of course that was only possible above AH which was 200ft and therefore usually coinciding with the CAT I minimum.
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Old 24th Oct 2017, 16:16
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If the autoland light flashes my company divides the problem into two parts:
1. RVR >300 m: Continue landing manually if RWY in sight, otherwise go around
2. RVR <300 m: in any case go around
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Old 24th Oct 2017, 16:20
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Slight drift: how many airlines have CAT 1 reversion from a CAT 2/3a ILS? It's a similar scenario to what Denti is discussing. I flew triple A/P Boeing with a auto land annunciator. Easy. I then flew for double A/P operators with CAT 3a fail passive. No auto land annunciator. Some operated CAT 1 reversion for an autloand system failures, other did not. I could never achieve an answer; perhaps they felt it too dodgy. Can't think why.
Regarding Alert Height; what, when & how do guys use this for a Fail Passive (2 A/P) approach?
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Old 24th Oct 2017, 16:54
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Originally Posted by RAT 5
Slight drift: how many airlines have CAT 1 reversion from a CAT 2/3a ILS? It's a similar scenario to what Denti is discussing. I flew triple A/P Boeing with a auto land annunciator. Easy. I then flew for double A/P operators with CAT 3a fail passive. No auto land annunciator. Some operated CAT 1 reversion for an autloand system failures, other did not. I could never achieve an answer; perhaps they felt it too dodgy. Can't think why.
We can revert if all settings and re-briefings are completed by 1,000'AAL; otherwise it's a G/A.
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Old 24th Oct 2017, 19:59
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Regarding Alert Height; what, when & how do guys use this for a Fail Passive (2 A/P) approach?
Alert height is integral to the fail OPERATIONAL concept.

---- 2 op:
My current and previous airlines WRITE nothing apart from what FCOM suggests, and beyond what is available from Airbus' Getting to Grips with CATII/III. Already quoted above.

Individual trainers and respected opinion makers SAY it is a technical and legal possibility to take over and continue manually, however:
In close limiting conditions such as those programmed into the SIM for the LVP excercise, pilots who attempt and land after autoland failure almost without exception regret that decision when asked to self-assess during the debriefing.
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Old 24th Oct 2017, 20:36
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Originally Posted by Jesse Pinkman
We can revert if all settings and re-briefings are completed by 1,000'AAL; otherwise it's a G/A.
+1 here

Originally Posted by FlightDetent
Individual trainers and respected opinion makers SAY it is a technical and legal possibility to take over and continue manually, however:
In close limiting conditions such as those programmed into the SIM for the LVP excercise, pilots who attempt and land after autoland failure almost without exception regret that decision when asked to self-assess during the debriefing.
This is LVO;very poor visibility,quite close to the ground(below 200ft),so we solely depend ourselves on the airplane and automation.Having said that there is very limited time to think/realize what was the cause of autopilot(s) disconnection and illumination of Autoland light.Most of us probably tend to miss all these facts.Early flare?Computer malfunction?ILS Transceiver failure?As already said,unless is something more serious combined than just a triple click itself(fuel leak,smoke,fire etc), for me it would be more wise to go around and give myself more time and space about the nature of the failure.And i think that is the general line given to the pilots in my current airline.
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Old 24th Oct 2017, 22:20
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Originally Posted by RAT 5
Slight drift: how many airlines have CAT 1 reversion from a CAT 2/3a ILS?
AFAIK, it's pretty much routine - or should be! I've encountered the conditions enough in my career that it was really a no-brainer after a while...

The common scenario is varying visibility, going between Cat I and Cat III. The easy solution is to brief a Cat III approach. That covers all scenarios, ending presumably with an autoland. Extend the brief to include the scenario that visibility is reported better than Cat III when on final. Include the option to continue with allowed degraded systems with the increased visibility, including a manual landing if Cat I.
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Old 24th Oct 2017, 23:29
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A/p failure(Disconnection) followed by manual takeover of controls AND LANDING requires an RVR of 350metres as per our company policy. If RVR is not 350 or above its a GA.

For a b777 Master Caution is inhibited below 200RA except for NO AUTOLAND
AUTOTHROTTLE SPEEDBRAKE AUTOPILOT

Should you get a AUTOPILOT msg with 75m RVR it's just GA.

Personally have been in a situation where RVR reported 100-150 Metres and have lost complete sight of runway (due fog patches) for few secs (both on takeoff and landing in night time) and lesson learnt that situation can become very dicey.

Should one try to manually takeover and land, I wouldnt trust 75m RVR will give much visual reference.
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Old 25th Oct 2017, 04:49
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Out of our B787 SOP.

Review Requirement for Mandatory Go Around

• If Insufficient Visual references: and

• Below 1000’ HAT;
• Remedial Instrument switching required.

• Between 1000’ HAT and 200’ RA (Alert Ht):
• ‘AUTOPILOT (DISC)’ Mast Caut/Warn;
• 'NO AUTOLAND’ Mast Caut;
• ILS/GLS deviation alert.

• Between 1000’ HAT and 200’ RA (Alert Ht) for CAT IIIB ops only:
• ‘AUTOTHROTTLE DISC’ Mast Caut;
• 'NO LAND 3’ - Mast Caut;

• Between Alert Height and the DH:
• ‘AUTOTHROTTLE DISC’ Mast Caut;
• ‘SPEEDBRAKE EXTENDED’ Mast Caut;
• ‘AUTOPILOT (DISC)’ Mast Caut/Warn;
• ILS/GLS deviation alert.

So, if you can see runway centreline lights, you can Land.

The A/P sets up for the flare and landing at 500' and again at 300', so in theory it should be all trimmed out and may just require a bit of back pressure to make a nice touch down.

the other issue is, if you do Go Around, make sure you manually push the trust levers up as the TOGA switches won't work if/when you make contact with the runway (EK 777 Dubai). there will be lots of ringing and dinging during the initial G/A until established climbing away due to the config change during the bounce. Always check the Altimeter for positive climb and the FMA to see what modes you've got before banging away on the TOGA switches.

This is our A320 SOP

If insufficient visual reference at DH.
If insufficient visual references and:

• Below 1000 ft HAT:
• Remedial instrument switching required
• Between 1000 ft HAT and 100 ft RA:
• • • • • •

Engine failure
Alpha floor activation
Any amber caution (single chime)
Loss of CAT II / CAT III – as applicable (triple click)
Autopilot off (cavalry charge)
No LAND on FMA at 350ft RA

Same same, but a little bit easier in the 'Bus as the GA mode will activate once the thrust levers are in the TOGA detent (from memory). still need to check for positive climb and the correct modes on the FMA.

Last edited by Roj approved; 25th Oct 2017 at 05:04. Reason: had a second though, and added A320 sop
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Old 25th Oct 2017, 08:37
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Some operated CAT 1 reversion for an autloand system failures, other did not. I could never achieve an answer; perhaps they felt it too dodgy. Can't think why.
One example is the thinking where we are:

1. SOPs say you shouldn't hand fly an IF approach for your own manual landing.

2. SOPS say in the event of an autoland being planned in CAT III or CAT 2 situations the landing pilot ( must be the commander) takes control ideally at 1000' (and only if and when LAND X etc annuciated, etc etc).

So...It's foggy, brief for a CAT2/3 autoland...off you set down the slope, co-pilot handling intially.

3. Lets say at 1100 feet you are surprised to hear CAT 1 complaint RVRs but stick with the autoland plan..so captain shortly thereafter takes control, autopilot OK at this point...

4. Then at say 500' and still in the clag the autopilot in entirety drops out..noisies, captions, etc including.."No autoland", etc...

Does the captain continue by hand flying it for his/her own manual landing?...Does he/she give control back to the P2 to hand fly it down to visual with the view of taking control again for a manual ....or do you go around and set up for an appropriate approach with the capability you have got...

Company answer for us, probably using the KISS principle, is you must not revert from a CAT III or II back to a CAT I....and yes, before the post cards roll in I didn't write the SOPs and I know what would do in the event of a Force Majeur such as a fire or very short of fuel.

Last edited by wiggy; 25th Oct 2017 at 10:33.
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