A330/A340 EAD (AoA PROBES)
 

An EAD has just been released following an issue experienced by an A330 crew:

The EAD includes the narrative:

Alors, qu'est que c'est un 'blockage' of an AOA probe? Does that mean blocked with foreign matter / ice / whatever, or is it some quaint Franglais referring to a stuck probe?

The EAD also states:

Followed by the "No Sh*t, Sherlock" statement:

You don't say!

Another piece of Froggldegook comes in the actual procedure and states:

I've heard of spurious stall warnings and have even experienced spurious stall ident and stick push at 500 ft in a much older 4-jet, I've taught 'incipient' stall recoveries and 'fully developed' stall recoveries, but never in 40 years have I ever heard of an 'undue' stall warning....

Just WTF do they mean?

Once again it becomes clear that every Airbua FBW aircraft pilot should know how to get out of the normal law.
As it seems the only safe way out of such mess.
Regrettably Airbus will continue to refuse to tell us.

Easy, reach up and turn off all 3 PRIMS.

You're now in in direct mode via the 2 remaining SECS. :ok:

However that would be a last ditch effort!!:{

This only applies to the newer aircraft with the new AoA probe that is mounted on a raised area away from the skin.

Considering every aircraft flying is at risk of undue stall warnings, I am surprised that you have not heard of it (sensor issue, radome damage, bird strike, ADC issue etc). An example would be the 777 incident out of Perth https://www.atsb.gov.au/media/24550/...503722_001.pdf

Safelife - I sincerely hope you are not a A3xx driver! You have multiple way's of getting the machine into Alt or Direct law easily within a few seconds, all of which you can find in the FCOM.

As stated in the above post - Switch of multiple PRIMS or ELACS, or FAC 1+2

Not ideal in the slightest however not some big AB secret and something you should most definitely already know...

'Undue' is defined as 'to a level which is more than is necessary, acceptable or reasonable'. As in 'use of undue force'

So, is an 'undue stall warning' something which meets this definition? Or is it yet another froggldegook mangling of English in this context?

I presume they mean a 'spurious' stall warning?

Regardless of the derivation of the word...
 

Does anyone seriously not understand what it's saying?

If so, you should probably not be in command of anything more dangerous than a pencil sharpener.

I have been following this shimmering thread that expands and contracts with time, with interest. There seems to be an almost obdurate unwillingness to understand the text of the EAD and of the Airbus concept of design and operation of aircraft. I have no problem with either, but then I operate Airbus aircraft and have done so for many years, and am familiar with the way they do things. It's not difficult, nor is it inherently dangerous, it is comprehensible and is designed to be so worldwide.

I do agree with your comment, except that, if i read correctly the report, the activation of the stall warning and stick shaker devices was justified in the Perth 777 case.

2 things i would like to see then :

1. A published Memory Item to get rid of undesirable protection activation
2. A single black guarded switch to trigger DIRECT LAW

Anyone to post the AD please ?

A330/A340 EAD (AoA PROBES)
 

In aviation it is frequently said that an experienced aviator is one that uses his exceptional knowledge in order to avoid having to use his exceptional skill.

The correlation to this thread is that I am able to understand (generally) what the people at airbus write, but I have to work at it sometimes.

The cynic in me suspects that it is not just a poor translation from French into technical English but a deliberate attempt to minimise adverse media coverage at the expense of clarity.

An undue warning seems much less emotive than a spurious warning when read as a newspaper headline!

''Anyone to post the AD please ? ''



http://www.caa.co.uk/docs/33/2012120...D20120258E.pdf

RISK OF UNDUE STALL WARNING is prompted by the ECAM in several malfunctions

The new bulletin tells us to switch off two ADRs to get in Alternate Law.

We don't want Direct law, direct law is dangerous

Amazing stuff, thank you.

Now, curions to read the exact :
"Blocked AOA probes" emergency procedure included in Airbus AFM A330 Temporary Revision (TR) TR293 issue 1 ?

bad day?
 

Exactly what kind of English are you referring to?

spectacles or yoke?
tailplane or stabiliser?
throttle or thrust lever?
VAT or VREF?
coaming or glareshield?
to dump or jettison?

What does it matter whether the AoA probes are blocked or stuck? All the pilot needs to know is that they are not working the way they should.

RISK OF UNDUE STALL WARNING : with a little bit of imagination it is not difficult to figure that one out.

@CONF iture;

Airbus A330/A340 AFM TRs can be found at:-

http://ad.easa.europa.eu/blob/TR293a..._2012-0258-E_2
http://ad.easa.europa.eu/blob/TR294a..._2012-0258-E_3

OK465

Roll direct is hardly a dangerous thing. Pitch alternate is Ok, no danger at all.

Pitch direct is dangerous, however. Many people thing that reverting to Direct law is like reverting to a conventional flight control system, but pitch direct is nowhere near conventional.

Thank you mm43.
I would be curious to hear more about the initial event and how the guys dealt with it ?

That Temporary Revision should also clearly specify how the procedure is meant to give back control to the pilots when protections do activate on unreliable data.
Give back credit to the pilots.

How is that different !?

Squawk7777, many of the items to which you refer have specific meanings and are not synonymous.

As for pilots should never need to do such a thing in response to QRH directions - which must be clear and unambiguous.

Ah but somewhere in all this the real world intervenes. Which is where common-sense (which in turn is based on experience) intervenes. I agree the QRH ought to be unambiguous, but, being written by mere humans, it occasionally is, no more so than for situations not dreamt of by the compositor. Which is where the Captain, using his experience, skill, judgement, imagination and flare, earns his money. And, should he survive, gets criticised by desk bound pedants.

True if you make minimal & smooth control inputs and your scan is working.

Not so true if you are ham handed, surprised, tired, and bumping along at night in the weather (particularly if you fly for a certain French airline it seems.):}

beardy, it would seem to me that during type rating training, you'd learn the terms and ask questions about what some of them mean, espectially if you were converting from another airframe.

I'll even bet that such discussion goes into training. ;)

Lone wolf, I do believe that you are correct. Some who contribute here, so freely, are so involved in training and are so far away from operations that they seem to have lost sight of reality.

So your comment implies flying an aircraft that needs to be trimmed and with manual thrust is dangerous. Quick - Ground all Boeings!!

No it doesn't, now stop being silly.

Why silly ... ?
You should maybe question the initial comment first :

Silly because you confused Direct Law with Boeing; there is no relevance. If you believe there is then you do not know what direct law entails, which, from your rather glib definition, I don't believe you do: you seem to (deliberately) misunderstand and in proposing the grounding of all Boeings you are being rather silly and possibly trying to be provocative. (Did I misunderstand your exclamation mark for an emoticon?)

I don't really have much to add to the technical discussion here since the contributors seems to be people who are unfamiliar with and are antagonistic to the aircraft. However, I don't think that Direct Law is dangerous, just different.

The issue people are trying to get at is that when you drop you're already in a higher than normal pressure situation and now flying a new beast. It can not be helpful considering all the details changes one must now deal with cognitively as opposed to autonomously. Take for example someone who ended up constantly pulling back on a stick which would have different results in each mode.

Warning! Thread Drift!!
 

BEagle,

if the QRH directions must be clear and unambiguous then there's not really a need for pilots to sit in the cockpit. They can be replaced by software, AI, Otto Pilot etc.

Having said that, I have been involved in incidents where thinking (shock, horror!) and system knowledge were required. Not all incidents and problems can be foreseen by design engineers. Decision making and interpretation are two of many factors that justify humans sitting and piloting airplanes (or aeroplanes if you wish ;) ).

I think what BEagle was referring to when he said

“pilots should never need to do such a thing in response to QRH directions - which must be clear and unambiguous.”

is documentation should be clear and unambiguous as much as possible, sure it is impossible to get things perfectbut a pilot has enough to learn and figure out without making things more difficult than necessary by providing loose documentation. Technical writers really have a big responsibility and they should have a good understanding of the words and be able to convey concepts clearly and unambiguously.

Imagine O'Leary told airbus to make a cheap airbus 320 version, without normal or alternate law. So they would be much much cheaper.

Well, he would be dissapointed. They cannot certify such aeronautical aberration.

The Airbus in direct law is much different than a 777 in direct law. It doesn't even have a proper pitch trim. We have a THS wheel, but we have no stick forces that we can trim.

In direct law you can fatally and brutally overstress the airframe with inputs that would not seem dangerous in normal or alternate law. In a 777 I believe you would still need to exert very high forces on the yoke to do that, in direc law.

Airbus Direct law is highly undesirable... Because it is dangerous. In the simulator, after a go around with a dual hidraulic... How does it feel? Conventional? No way! Normal and alternate feel conventional. Direct is more like a 767 with the yoke artificial feeling inop. MANOEUVER WITH CARE is not a silly ECAM line. You better manoeuver it with care!

With the trim wheel you don't trim forces, but you have to ease back the sidestick to neutral as you move the wheel, resembling the action of trimming. It is just like the microsoft FS with a joystick? That is NOT conventional. It doesn't feel right for a pilot instinct.

Cool Guys - precisely!

As for calls to provide an Immediate Direct Law option, that would be extremely undesirable for many flight phases as the sidestick lacks conventional force / displacement artificial feel simulation. However, an Immediate Alternate Law option would perhaps not be unreasonable, rather than a workaround involving the deliberate deselection of air data reference units.

Under what circumstances do you think you would wish to select Alternate Law and which flavour of Alternate Law do you think you would like?
Bearing in mind, of course, all those circumstances when the aircraft will give you Alternate Law automatically.

Since most of the uncommanded A320/330/340 flight path excursions which have been reported seem to have involved incorrect sensor information being faithfully acted upon by Normal Law protection features, the minimum necessary action to countermand such spurious events before an extreme event is reached would perhaps be appropriate - so probably Immediate Alternate 1 ?

Far better though to eliminate any source of sensor failure in the first place.

So this is what you would like to happen:

If I read you correctly you are advocating that with a faulty sensor input leading to the aircraft believing it is going too slowly, you would like it to revert to Direct Law. IMHO that is a not a very good idea. Far better to have angle of attack protections in Normal Law.
Perhaps you have tried your theories out in the sim?

Such an event would surely require the 'Unreliable Air Speed' procedure, rather than a deliberate selection of Alt Law.

The situation which raises greater concern is faulty AoA signalling, resulting in spurious pitch excursions. Under such circumstances it might be better to inhibit AoA protection by deliberate crew action, before the aircraft reaches an extreme attitude.

• In direct law, the pilot uses the THS conventionally to fly in trim.
• Use small control inputs at high speed, since in direct law the controls are powerful.
• MANEUVER WITH CARE
• The sidestick is directly coupled to the controls via the computers, but without any of the stabilization feedbacks. In effect, this law turns the aircraft into a conventional aircraft
• The flight crew must fly the aircraft carefully at all times. Control is precise, but there are no protections.

Those are comments from the FCOM, hardly synonyms of 'DANGER', but applicable to any aircraft.

When is the last time you flew direct law, in the sim at least ?

I know what the FCOM says, but the airplane in direct law is NOT turned into a conventional airplane. Because conventional airplanes must have stick forces that provide pilots with aerodynamic feedback. Without that, you are in the MIrcrosoft FS, which is not conventional at all.

Nearly every sim I fly direct law, for a while. The difficulty and danger of Direct Law is more apparent in the GO AROUND. Typically we find it in final approach, after L/G DOWN. The airplane is almost in trim and it takes only minor inputs and trim settings to have the job done. However, all that changes in case of go around. Then, it is difficult to switch my mind to direct law, so I find myself releasing the sidestick (springloaded to neutral) after inputs, which equates to make brisk inputs back and forth, like jerks. If more angle the input had, the worse. Imagine a conventional 767 where there is no feedback from the yoke, but it will return to neutral if you release it.

With practice you can fly direct law quite decently, but you have to actively think so that your instinct and habit doesn't put the airplane at risk. And, as I say, you could not certify an airplane with a direct law system without artificial feeling in the stick.

That FCOM reference repeats a lot that you fly with care, that you are not protected, that controls are powerful, that you use small inputs... That sounds like "hey be careful" to me, and therefore there is danger.

Dangerous means that you can get in trouble easily and you have to be careful to stay out of trouble. It doesn't mean you have to panic and pray. I will never revert to direct law on purpose as a reversion to conventional, because it is not a reversion to conventional, in the first place. Normal law is much more conventional than direct law, in my opinion.

The bulletin procedure is just what the situation needs. You get rid of the rogue sensor inputs and keep flying almost normally (alternate law is very much like normal law, except for some protections).

This represents a welcome change of tone from your mocking first post. However, it seems that you think that Airbus have not considered, risk assessed nor trialled what you propose. I do not know if they have or not, but I do know that their resources and knowledge and greater than mine or yours and that their investment, both in cash and reputation, is much more than yours or mine. Since I operate the aircraft, I have to trust them and their judgement. This does not stop me questioning, but each time I have questioned Airbus there has been a satisfactory response. If your are an operator or client they are quite willing to help, perhaps that would be a more suitable channel for your scepticism and offers of suggestions.

The significant change is from manoeuvre demand to attitude demand. However, the control system doesn't provide any stick force per G gradient, neither does it provide any Q-dependent feel. So perhaps not all that conventional?

beardy, I note your post. However, I remain somewhat exasperated by the....let's call it 'unusual' English used by Airbus in many of their publications.

But the Question is why would you release it in the first place as long as a pressure on it is necessary to maintain a requested attitude ?

Which brings me to the next question :
What's your experience really outside that airbus ?

You don't put your airplane at risk if your own way is by adopting brisk inputs back and forth, at most you make people sick in the back.

IMO you clearly need to reevaluate the basic behind piloting but also your notion of DANGER.