A320 A/P disconnect

[MD83FO]

On a CAT I ILS approach, what is the lowest height the A/P can be disconnected with CAT 3 DUAL on FMA?

[sabenaboy]

I couldn’t find a definite answer in the FCOM.
Did find this:
- 160 ft AGL, but that’s without Cat II or III on the FMA
- “If the flight crew performs an automatic approach without autoland, the autopilot must be disengaged no later than at 80 ft AGL.” (For a Cat II approach)
So my answer would be: (unless company SOP's are more restrictive)
You can leave the A/P on and perform an auto land OR disconnect AP no later than 80 ft AGL if not performing an autoland.

[FlightDetent]

With CAT3 DUAL displayed, in normal case, there is no height AFM limitation for AP disconnect.

FD.

[juliet]

You're flying a cat 1 approach so 160' according to my books. It's always going to say cat 3 dual if the capability exists.

Obviously if you're doing a practice auto land that's different, but that's not the situation you specified.

[sabenaboy]

You're flying a cat 1 approach so 160' according to my books
If you're using a standard Airbus FCOM you will find in FCOM-LIM-22-10:
ILS approach when CAT2 or CAT3 is not displayed on the FMA .................................. 160 ft AGL

To me that means that when doing a CAT I approach with 2 AP's and CAT 2 or 3 displayed on the FMA, there's nothing in the books stopping you from keeping the AP on until 80 ft AGL.

[FlightDetent]

To me that means that when doing a CAT I approach with 2 AP's and CAT 2 or 3 displayed on the FMA, there's nothing in the books stopping you from keeping the AP on, full stop. Corrected for you. :D

[sabenaboy]

Corrected for you. :D

Yes, you're right. I would recommend to switch them off to leave the runway. ; -)

[FlightDetent]

I'd heed that call! Anyways, in case the pilots plans to disconnect, what would be the lowest height to do so? I like your 80 feet, though I do not recall any specific reference in the OEM books. Most likely because Airbus sees no need to teach airlines to fly.

Does any sort of FLARE MODE happen on the 330/340? If so, would it be the same 50 feet as on the thin-bus?

regards, FD.

[juliet]

Bit of common sense here people. You've said that you're flying a Cat 1 ILS. So you've briefed a Cat 1 and then been cleared for a Cat 1. Are people on here seriously suggesting that they will leave the autopilot in and allow the aircraft to autoland? Without a clearance for such and therefore without the sensitive areas protected, or a statement as such from tower and an acknowledgement from you?

As I read it that line in the FCOM gives an allowance for us to fly Cat 2/3 approaches. I agree it isn't particularly clear, perhaps read it as "ILS approach when not flying a Cat2 or Cat3 approach."

Juliet

[FlightDetent]

Juliet, I beg to differ, perceived common sense does not take over here.

That line in LIMITATIONS is very clear and reads exactly what is printed. Minimum height for autopilot use with CAT 1 displayed is 160 ft. Meaning, that if your FMA displays CAT 1 the autopilot is only certified to 160 feet.

With CAT 2 or better displayed there is no technical limitation for autopilot disengagement, as indeed the aircraft is autoland and rollout capable.

Noted though, there is a paragraph "Autoland in CAT 1 conditions" or similar. I would agree with what you suggest completely, but not within the scope of OP's question.

take care, FD.

[juliet]

I think it is within the scope of the question. OP is asking when to disconnect the AP on a Cat 1 approach. Leaving it in till landing is an autoland, not a Cat 1.

[seen_the_box]

Are people on here seriously suggesting that they will leave the autopilot in and allow the aircraft to autoland? Without a clearance for such and therefore without the sensitive areas protected, or a statement as such from tower and an acknowledgement from you?

We're permitted (indeed required) in my airline to fly practice autolands, when weather is CAT I or better. There's no requirement to tell ATC, or for the sensitive areas to be protected in such a case. The operating minima remains CAT I.

[FlightDetent]

s_t_b: seconded. In similar fashion, e.g. during LVP training, the minima is CAT I but it is autoland with all the bells and whistles.

yours, FD.

[juliet]

So when you are doing a practice autoland do you brief the appropriate contingencies? Failures below 1000', alert height, no autoland warning etc? I certainly hope you do.

An autoland is not a Cat 1 approach. A practice autoland as mentioned is a Cat 3b flown within the met parameters of Cat 1 (invariably).

[Amadis of Gaul]

Even if there's no requirement to advise ATC, I make a point of doing it. Just one more t crossed, I suppose...

[Feather44]

- CAT 1 is an ILS Approach TYPE
- CAT 3 DUAL on FMA is an Auto Flight / Autoland CAPABILITY

Provided you did request (to practice autoland) and have been cleared by ATC, you can keep your AP up to taxi speed (20kt if not mistaking)

[FlightDetent]

Even if there's no requirement to advise ATC, I make a point of doing it. Just one more t crossed, I suppose... Same here.

[seen_the_box]

So when you are doing a practice autoland do you brief the appropriate contingencies? Failures below 1000', alert height, no autoland warning etc? I certainly hope you do.

An autoland is not a Cat 1 approach. A practice autoland as mentioned is a Cat 3b flown within the met parameters of Cat 1 (invariably).

Some CAT I approaches require an autoland in this outfit (CAT I LTS), and at some operators CAT II/III approaches don't necessarily end in an autoland (aircraft fitted with HUD guidance, for example). You're getting confused with the terminology. If the manufacturer and your company allows it and the aircraft is appropriately certified, you can do an autoland off any type of approach you choose (although of course in practice I can't think of an aircraft type which can autoland off anything other than an ILS/MLS).

As to your first question: the whole idea is that we brief and fly the approach as a CATIIIb approach and autoland. Therefore, we tend to run through the standard low vis briefing points (task sharing, standard calls etc.) However, clearly go around decision making is different in the practice case to the real one. We tend to brief that if we get a loss of CATIII/ auto land warning light etc. and we can safely revert to CAT I, we'll continue the approach manually to avoid an unncecessary go around.

Provided you did request (to practice autoland) and have been cleared by ATC, you can keep your AP up to taxi speed (20kt if not mistaking)

Certainly on our route network (Europe) there is no requirement to tell ATC. It doesn't change anything for them, and therefore they're not interested. We used to do it, and would invariably be met by silence, then a confused 'Roger' and occasionally a 'LVP protections are not in place.' It may be different in other parts of the world of course.

[safetypee]

TYPE includes weather, crew qualification, and ILS ground station and airport facilities.
CAPABILITY relates to the integrity of the auto-flight system.

Some Cat 1 ILS’s are suitable for practice autolands, but approval usually includes an understanding of the pre threshold terrain and the need for the crew to take responsibility for additional monitoring in case of deviation. Similarly for Cat2 /3, just because the ground station and airport facilities are suitable in poor weather this does not mean at all times, particularly if the protected zones are infringed or the ground station is operating single channel.

If a high accuracy, high integrity auto-flight system is flying with a poor quality input (Cat 1, or Cat2/3 unprotected beam) then a high accuracy output cannot be assured – review ILS beam, pre threshold and runway ground profile, and protected zones.

EURO Doc -013 via ICAO (now probably superseded by EASA docs)
6.8 Autoland operations when LVP are not in operation
6.8.1 ILS installations may be subject to signal interference by aircraft and other objects. In order to protect the ILS signal during operations in Low Visibility Conditions the sensitive area is protected during LVP. This ensures that the accuracy of the ILS signal is maintained.
6.8.2 There are a number of occasions when pilots wish to perform autoland operations when LVP are not in operation. These may be for pilot qualification and recency, for operational demonstration and in-service proving flights and for system verification following maintenance. In particular, some aircraft operators recommend that their pilots perform autoland operations routinely in order to reduce pilot work load during marginal MET conditions and after long haul flights.
6.8.3 When LVP are not in operation, it is possible that aircraft and vehicles may cause disturbance to the ILS signal. This may result in sudden and unexpected flight control movements at a very low altitude or during the landing and rollout when the autopilot attempts to follow the beam bends. As a result pilots are advised to exercise caution during these operations according to the instructions provided in their Operations Manual.
6.8.4 Pilots should inform ATC if they wish to conduct an autoland with protection of the LSA. In this case, ATC must inform the pilot if protection of the ILS/MLS sensitive area will or will not be provided. In some States, the hours where practice autolands are permitted are published in the AIP.

Examples from national authorities:-
http://www.caa.gov.qa/sites/default/files/FOIL%2001_04_use%20of%20Auto%20land.pdf
AIP for SWITZERLAND (section AD-1.1) valid from 17 SEP 2015 (http://eaip.austrocontrol.at/all/ls/150917/eAIP/2015-09-17/html/eAIP/LS-AD-1.1-en-CH.html) (para4.5.2)

http://www.pprune.org/tech-log/279058-capturing-loc-gs-2.html#post3337711

[juliet]

STB - Im not getting confused at all. The OP asked about AP disconnect on a Cat1, no mention of autoland practice or otherwise. Cat3B, as you say, is a capability that will always show up providing conditions are met.

Obviously ATC requirements for a practice autoland vary around the globe. I do find it surprising that ATC aren't covering themselves by declaring the sensitive areas not protected.

[Amadis of Gaul]

One little gotcha with keeping the AP on all the way to 20kts or whatever on the 320 is that 45-50 seconds after touchdown, the FMGC goes into the Done phase, so the localizer freq drops out. You would need to manually tune the loc to prevent that from happening.

Just something to keep in mind for those who are hellbent on keeping the automation on a tad longer than most...

[No Fly Zone]

If it is a simulator practice, know what is expected in the SOP and fly it. If in Real Life, why the :mad:did you not divert about 30 minutes ago? In the rare case where a diversion is/was not possible - very rare and you ought to know that, follow the SOP or get a low as possible, shut ALL of it off and land the monster with whatever grace remains possible. That may be a challenge with airplanes that are a bit too smart for their own good (think French FBW types), but one more reason to ask questions within your own shop. Colleagues? Trainers? FOM writers? Chief Pilots if necessary. What it really means is know As Much As Possible about how that semi-stupid FBW system works and learn how to tell the SOB who is driving. Just by asking the question, you are far ahead of many/most others. This forum many not be the best place to find good answers, but please don't quit until you are satisfied. If you drive one of those (FBW) things, you really do need to know how it thinks, ahead of time. If not already obvious, if forced to land in that situation, you'll know it well before hitting the markers. Thoroughly brief your partner and know what each is expected to do, when, long before said markers. Those miserable approaches and landings CAN be made safely, but they require TWO sharp pilots who can out-think the damn FBW and have an absolutely firm plan, regardless of who is PF and PM. That is darn sure not the time to be asking the infamous question, '...what is it doing, now...?' Stick and rudder is not enough. Know your airplane, inside and out and keep your brain several steps ahead of the airplane's brain. Few do; all should.:{

[FlightDetent]

NFZ: say again? Or is it a reply to post that is no longer visible?

fd.

[Amadis of Gaul]

Just a garden-variety anti-Airbus rant (that has nothing to do with the question at hand to boot), no biggie.

[mcdude]

I think the question is better written:

"I'm planning to perform a manual landing in equal or better than Cat I conditions with CAT2 or CAT3 displayed on the FMA. What is the lowest I can keep the autopilot engaged?"

I would say the correct answer is 80 ft AGL.

[Citation2]

There is no clear cut answer to this question as there is no limitation .
FMA is showing its highest performance level which is CAT3 DUAL , it does not mean you can go down to cat 3 minima . Are you limited by crew qualification? Airport not authorising simulated cat 3? With AP ON , Passing DH , you are more doing a simulated CAT 3 approach than CAT 1. Or if you plan to disconnect by 80 feet you are then doing a simulated CAT 2 as Autopilot is not mandatory for a CAT 1 , and manual landing is required.

Now let's ask another question , simulated CAT 2/3 are not allowed in a busy airport in cavok weather.
Having CAT 3 DUAL on FMA , what is the lowest height at which you can disconnect AP?

I would say DH CAT 1 . Although your autoflight can do better , you are here limited by local airport requirements.

[FlyingStone]

Citation2, I don't think you understand the difference between aircraft capability (e.g. indication on FMA), approach type and related minimum altitude for autopilot disconnect.

Airbus FCOM is actually quite clear on this topic (especially compared to some other French "tricks"). If FMA is showing CAT 1 capability, you should disconnect the autopilot at 160ft the latest. If you have CAT 2, CAT 3 SINGLE or CAT 3 DUAL and you plan a manual landing, you should disconnect it at 80ft. Of course, everything assumes an ILS approach - for NPA, limitations are different.

Minimum height for use of the autopilot in:
- ILS approach when CAT2 or CAT3 is not displayed on the FMA ...160 ft AGL

and

If the flight crew performs an automatic approach without autoland, the autopilot must be disengaged
no later than at 80 ft AGL.

There is no reason why you can't use autopilot on a normal Category I ILS approach until 80ft - provided FMA displays capability CAT 2 or better and aircraft remains in desired flight path of course.

[Citation2]

Flyingstone you are confused with autoflight limitation and what the pilot yourself is actually doing .

If you are disconnecting the autopilot at 80 ft you are doing a simulated CAT 2 approach with manual landing.

Well quoted "If the flight crew performs an automatic approach without autoland, the autopilot must be disengaged no later than at 80 ft AGL.". This appears under ILS CATEGORY CAT 2 on FCOM limitations.

[Sailvi767]

You can never disconnect the autopilot in the Airbus unless you pull circuit breakers to disable computers and put the aircraft into direct law. You can put the aircraft into control stick steering. This will work at any altitude. Minimum altitude to switch to CSS will be governed by your airlines SOP. My airline uses 50 feet below minimums or normally 150 feet on a CAT 1 approach. Disconnect can be down to flare if the approach is not satisfactory. I solve the issue by always flying cat 1 approaches in CSS to maintain currency in the Airbus version of hand flying. Why anyone would couple a cat 1 eludes me. The airplane can fly it just fine. Pilots need practice for the day things go wrong and you must fly the aircraft.

[mcdude]

Sailvi767 - you seem very confused. The autopilot on the A320 is conventional and is disconnected by a button on the sidestick. There is no such system as CSS on Airbus.

Citation 2 - please read the original question in the first post. FlyingStone is bang on the money.

[sonicbum]

Quote from JEPPESEN - GENERAL - RADIO AIDS - ILS

"Unless otherwise coordinated through Flight Standards, ILS signals to Category I runways are not flight inspected below the point that is 100 feet less than the decision altitude (DA). Guidance signal anomalies may be encountered below this altitude."

Whilst I do agree with the discussion pertaining on AFCS limitations vs approach category, are you still legal in that scenario if, as an example, your CAT I DA is 300 ft AGL ?

[Citation2]

MCDUDE : the original question is : On a CAT I ILS approach, what is the lowest height the A/P can be disconnected with CAT 3 DUAL on FMA?

The answer of flyingstone : 80 feet
"FCOM LIMITATION : ILS CATEGORY 2 : If the flight crew performs an automatic approach without autoland, the autopilot must be disengaged no later than at 80 ft AGL"

Now who is confused ?can' t you read your FCOM ? 80 ft is a limitation only applicable to CAT 2 . Why are you inventing a new non existent limitation?
80 ft is not applicable to CAT 1

If you were keeping the Auto pilot down to 80 feet thats exactly what you would be doing if you asked for a simulated CAT 2 approach.
So again if you are keeping the autopilot down to 80 ft , that's called a simulated CAT 2 and not CAT 1 approach.

[sonicbum]

MCDUDE : the original question is : On a CAT I ILS approach, what is the lowest height the A/P can be disconnected with CAT 3 DUAL on FMA?

The answer of flyingstone : 80 feet
"FCOM LIMITATION : ILS CATEGORY 2 : If the flight crew performs an automatic approach without autoland, the autopilot must be disengaged no later than at 80 ft AGL"

Now who is confused ?can' t you read your FCOM ? 80 ft is a limitation only applicable to CAT 2 . Why are you inventing a new non existent limitation?
80 ft is not applicable to CAT 1

If you were keeping the Auto pilot down to 80 feet thats exactly what you would be doing if you asked for a simulated CAT 2 approach.
So again if you are keeping the autopilot down to 80 ft , that's called a simulated CAT 2 and not CAT 1 approach.

Agree with the above.

[LW20]

Quote:
Certainly on our route network (Europe) there is no requirement to tell ATC. It doesn't change anything for them, and therefore they're not interested. We used to do it, and would invariably be met by silence, then a confused 'Roger' and occasionally a 'LVP protections are not in place.' It may be different in other parts of the world of course
:ugh::ugh::ugh:

I am shocked how stupid pilots with the responsibility for hundreds of lives are.
@seen_the_box: Have you ever read about the SIA B777 ending off the runway in munich? They made an auto land on an CAT I ILS beam without telling ATC. So just as touching down the previous departing aircraft overflew the LOC antenna causing the localizer to bend. The B777 followed it and departed the runway.
Munich by the way is in the middle of europe.

[FlightDetent]

So again if you are keeping the autopilot down to 80 ft , that's called a simulated CAT 2 and not CAT 1 approach. Rubbish yet again. If I disconnect AP at 1200', is it a visual approach then?

[seen_the_box]

Part of the briefing for a practice autoland will cover the fact that LVOs are not in force, and the beam will not be protected. We are therefore prepared to take over manually and complete the landing, assuming visual references are sufficient (which they should be, considering that by definition the weather for a simulated autoland will always be CATI+). It is part of the TEM when flying such an approach.

I'll say it again: There is no requirement to tell ATC that you are conducting a practice autoland. It doesn't change anything for them: at a busy airfield, they are not suddenly going to give you low vis protections just because you want to practice. The SIA incident you cited could have been avoided if the crew had disconnected the automatics when it became clear that they weren't coping adequately with the situation, or flown a go around/baulked landing. They allowed the autopilot to steer them into the grass. Proper briefing, and proper monitoring is imperative to avoid such an occurrence.

[LW20]

I believe you, that, according to your company sop, there is no requirement to tell atc. But as the SIA shows you, they were not able the cover the outcome of this.
If you tell ATC in a busy environment that you will practice autoland, they will never protect the respective areas around the runway. Instead they tell you to land manually, because autoland is not save on an unprotected ILS beam. Even if Chuck Yeager, or someone who thinks he is, is on the controls.

[seen_the_box]

Instead they tell you to land manually, because autoland is not save on an unprotected ILS beam. Even if Chuck Jeager, or someone who thinks he is, is on the controls.

No, clearly they won't 'tell you' to do anything. It's none of their business how you decide to land the aircraft. They will tell you that low visibility protections are not in place (which you would already know), and it's up to you as the PIC what you choose to do with that information.

There is nothing inherently 'unsafe' about an autoland on an unprotected beam: as I already stated, you just have to have a plan in the event that the beam is compromised. If it was unsafe, it certainly wouldn't be permitted in line operations, either by company or manufacturer. The fact that it is permitted should be a pretty clear indication that it is not considered unsafe. You always have the option of taking over manually, or going around.

[FlightDetent]

Certainly on our route network (Europe) there is no requirement to tell ATC. It doesn't change anything for them, and therefore they're not interested. We used to do it, and would invariably be met by silence, then a confused 'Roger' and occasionally a 'LVP protections are not in place.' It may be different in other parts of the world of course My understanding is the same and I experienced likewise. OTOH, ATC at some airports seems to have their own set of NON-LVP autoland procedures that can be helpful to aircrew too.

The 777 incident in Munich was a case of autoland gone wrong in non-LVP (protections not in place) situation, yes. Factual report here from BFU. (http://www.bfu-web.de/EN/Publications/Investigation%20Report/2011/FactualReport_11_EX010_B777_Munic.pdf?__blob=publicationFile )

[sonicbum]

Quote from JEPPESEN - GENERAL - RADIO AIDS - ILS

"Unless otherwise coordinated through Flight Standards, ILS signals to Category I runways are not flight inspected below the point that is 100 feet less than the decision altitude (DA). Guidance signal anomalies may be encountered below this altitude."

Whilst I do agree with the discussion pertaining on AFCS limitations vs approach category, are you still legal in that scenario if, as an example, your CAT I DA is 300 ft AGL ?

Reply to self : yes as long as you are ready to take over manually at any sign of disturbance. Furthermore Airbus recommends that ATC is informed when making practice auto lands in CAT I or better weather conditions (GTG with CAT II/III). We are drifting off the subject I believe as the OP question is about manual landings.

[Sailvi767]

When you push the disconnect button on the Airbus you are not disconnecting the autopilot. You are changing the inputs the autopilot receives to fly the aircraft to the side stick from the FCU or MCDU. The rest of the aviation world calls this control stick steering or CSS. You are correct Airbus does not use this term but a duck is still a duck even if you call it a chicken.

[sonicbum]

When you push the disconnect button on the Airbus you are not disconnecting the autopilot. You are changing the inputs the autopilot receives to fly the aircraft to the side stick from the FCU or MCDU. The rest of the aviation world calls this control stick steering or CSS. You are correct Airbus does not use this term but a duck is still a duck even if you call it a chicken.

Sailvi, are you rated on any Airbus FBW airplane ?

[Sailvi767]

Current and flying the A330.

[sonicbum]

Current and flying the A330.

I see. Anyway when you disconnect the autopilot you do hand fly the airplane with the different flight control laws according to the STS of the airplane and/or to the flight phase that you are in. When the A/P is off, it is OFF.

[FlightDetent]

Current and managing the AP of A330. There. With all the best regards for you, :D
FD.

[Togue]

I think it is semantics. Sailvi767 has a valid point. I have to accept that I never thought of it this way but it makes sense. Some OEM may call it CSS, other CWS ( Control Wheel Steering ), etc. Something similar to ECAM and EICAS or TCAS and T2CAS. Even Winglets, Sharklets, Win Tip Fence, etc.

[sonicbum]

I think it is semantics. Sailvi767 has a valid point. I have to accept that I never thought of it this way but it makes sense. Some OEM may call it CSS, other CWS ( Control Wheel Steering ), etc. Something similar to ECAM and EICAS or TCAS and T2CAS. Even Winglets, Sharklets, Win Tip Fence, etc.

I respectfully disagree. The reason the airplane "stays where you put it" whilst hand flying is due to the load factor demand in pitch and roll rate demand in roll (considering only normal law here). There are numbers of thread where some extremely knowledgeable contributors have provided highly detailed informations on the FBW logics.

[mcdude]

Sailvi767 - It's a while since I flew the A330, but take a look at your FCOM schematics. With the AP engaged, the FG part of the FMGEC provides autopilot commands to the FCPCs (PRIMs). With the autopilot disengaged the sidestick provides those commands to the PRIMs. Regardless, when the AP is off, it is most definitely off. Are you confusing the AP with the PRIMs?

Citation2 - I am not trying to invent nonexistent limitations, rather I am trying to clarify what is poorly explained in the FCOM Limitations and much better explained in the AFM. Your previous post uses "CAT 1" and "CAT 2" a lot which worries me. These terms are FMGC capabilities, not minima or types of approach. Did you mean CAT I / CAT II? You do understand the difference? Minima is irrelevant when dealing with AUTO PILOT FUNCTION limitations. (It is relevant for Autoland though). Basically in this context, an ILS approach is an ILS approach is an....

I'll simplify the original question even more: you are flying an ILS approach and intend to manually land. What is the lowest height I can keep the AP engaged if the FMGC capability of "CAT2" or CAT3" IS displayed on the FMA? Clue: the answer is 160 ft AGL if "CAT2" or CAT3" is NOT displayed on the FMA...