BOAC;

Re, "Whether the 'automatics' brigade like it or not, some of the programmed features of the AB system contributed to both 447 and the 330/340 events. Note I say 'contributed to' and not 'caused'. "

In the sense that all complex systems are capable of inciting inappropriate interactions with users, yes, I agree with you BOAC. "What's it doing now?" isn't a state of mind limited to Airbus aircraft. And when one encounters such moments, one quietly and calmly disconnects everything (including thrust levers) and flies the raw airplane - and as has been observed, the Airbus, as does the Boeing, fly beautifully, manually from takeoff to cruise altitudes, descent & landing - one just has to know a bit about high altitude, high Mach number, swept-wing aerodynamics.

But given this, what do we do with the Tripoli A330 (and for that matter, the Gulfair A320) accidents? Both aircraft were perfectly serviceable. What kind of automation would be able to "decide" in time, that the pilot was suffering from somatogravic effects? If the assumption is that automation can be designed/created to serve any ends, then how do such solutions differ from the present "zoom climb" issue, (extremely rare though both "contributions" may make in a fatal accident)?

If I may be permitted to wander slightly, the "possibility-potential", (possibilistic thinking, according to Lee Clarke), is what facilitates this thinking. To me anyway, the difficulty for the designers and the engineers becomes making an assessment between two polar opposites - What's probable?, vice What's possible? The question goes beyond "excusing or blaming" - it's just trying to find out what the causal pathway (to which you referred) was; in the case of AF447 I think we have it.

It seems to me as a retired pilot, that in terms of the designer/engineer's work (speaking specifically of Airbus), we can only say that the approach was(is) sufficiently cognizant to consider and expect that an airline pilot would be trained against, and would avoid-like-the-plague, stalling his/her aircraft and would understand those circumstances which would lead to stall entry.

On the question of "NCD" and the cessation of the stall warning, such circumstances may be imagined as "possible", but (at the time) reasonably concluded as "improbable". We now have the one single outlier (in tens of millions of flight hours), that, we might say disproves the thinking, (and inadvertently led to confusion in circumstances so far from normal as to be beyond test-pilot territory), so now, what do do but find a way to keep the stall warning on at all times if the airplane is indeed stalled. I believe (but do not know) that this is more complex and difficult than those who may liken such "obvious" solutions as the C-150 or other mechanical devices, etc) to present day computer/software systems but no doubt it will be done and certified; I believe the B777 system behaves the same way, (not sure about the B787) - perhaps someone here can confirm either way?).

The present call by some for "more automation" is, to me, folly, however the perhaps-two-dozen stall accidents, most fatal, over the past dozen years or so means there is a trend and not just an anomaly.

The discussion of why and in what condition the airplane (B or A) is "handed back" to the crew precisely at the moment when they could use "automation" is a very complex question having to do with "decidability" in computing systems and has, I truly believe, been exhausted in the ten AF447 threads, (for those new to the discussion, you can use the AF447 Search Index tool and look up "Byzantine fault"!),

When a complex system like a transport aircraft is taken into areas beyond its operational limits, the risk and possibility of confusion, particularly if one does not know one's aircraft well, compounds and heightens, quietly at first, and rapidly if one has been building/maintaining only a "surface" situational awareness.

The other aspect is the continued operation of the THS while the stall warning was active. As we know well,, the THS reached about 12°NU by about FL350 on the way down after almost continuous nose-up stick inputs. (it should be noted that with continued ND stick inputs, the THS would have returned to its normal position of about 2° NU).

What is to be done in terms of "automation" design under such rare and inappropriate circumstances, that won't cause other, unimagined and perhaps more serious circumstances when someone else wanders well off the beaten track? How are such scenarios imagined and "protected" against? As others have observed, if/when changes highlighted by AF447 are installed and certified, the "automatics brigade" and the hand-bombers could still ask your question with equal reasonableness.

So, not disagreeing with you...just pondering where your (and others') comments on the two primary observations on this accident, (stall warning quits; THS continues to trim), do take us in terms of solutions.

DonH - to try to answer your questions:

The stall warning 'quit' due to airspeed and not AoA reading, I believe? Simple solution - keep it functioning whatever the speed without WoW. Unless the AoA readings are 'borked' due to failure/icing/whatever, at least there will be a 'nudge' to the crew (did they really need it!!??) to see if alpha might be a touch on the silly side.

THS - moons ago on one of the interminable threads, I flippantly suggested a spring loaded boxing glove in the dash, but then offered a more serious proposition that 'we' derive a suitable boundary for 'reasonable' nose up THS (surely not difficult?) and then insist on a physical over-ride to exceed it - such as a 'cancel the limit' button.

bubbers44
 

A friend who flies a 7X (he calls it a 7 Edsel) hand flies it as much as possible. I do the same raw data, even in the sim. Preventing automation dependency can be a self-regulating endeavor. Obviously, some departures and arrivals require automation, but outside that there are opportunities if one has the stomach and professional integrity for it.

Its a start...

That is correct, I'm not so sure about the rest. The report doesn't say that alpha-floor was activated. It should have activated somewhere between alpha-prot and alpha-max, but maybe that threshold wasn't reached?

Quotes from rudderrudderrat:

"I believe Alpha Floor was triggered (at a certain Alpha threshold)."
Yes, the AAIB thinks it probable because the captain saw a PFD message starting with "Alpha...". They also said that Alpha Prot was (briefly?) exceeded, which - as HN39 says - would be necessary for Alpha Floor.

"With no side stick input, the aircraft will then maintain Alpha Prot angle of attack."
Quite. Re my question in a previous post, I've recently "gone to specsavers" and found the criteria for Alpha Prot disengagement on the A340 clearly stated :ouch: in the AAIB Bulletin:
Sidestick forward more than 1 second
OR
Sidestick more than half forward.

Hi BOAC,

You are correct. Normally the stall warning is tied to AoA, but because the sensed valid airspeed dropped to below 60 knots, the aircraft believed it was no longer flying and the stall warning ceased. At least that is my interpretation of this.

Re: 330/340 o'speed near miss not AF447
 

In the 330/340, alpha floor is inhibited above 0.53 IMN, which at 37000 feet is 166 KCAL. Doubt they got that slow.

According to the report, the message was 'alpha lock', which in the 330/340 is slat/flap related.

Desert185,

NG autopilot also disconnects with an ADR module discrepancy(s). And it has no fallback to fixed gains and flight path stability, just piloting.

If you recall the early 727, both the block 50 (and later 150) A/P would not disconnect in a situation where it really would have been desirable for it to do so. With a complete hydraulic failure the A/P remained engaged (electrically) when it in fact could exercise no control over the flight control surfaces.

A little red light with both A & B system bulbs was added right below the 'stab out of trim' amber light to warn that the A/P was engaged and either the selected A, B, or AB function was not available.

You takes your chances.

Turbine D,

Slightly more accurate would be to say that the ADIRU which processes the data it receives from the AoA sensor (and other air data sensors) considered the AoA value invalid and sent the code NCD to the other airplane systems.

To my knowledge, the ADIRU doesn't know and doesn't care whether the airplane is flying or not.

DonH,

Thanks for your reply on the memory list. In the early days of the AF447 Technical threads and the R&N threads, we went through this a few times. Although the information was made available in Airbus presentations several years prior to the AF447 incident, some of us questioned whether or not this was really made available to all airline line pilots through initial training or reoccurring training. If you look at the thirty some incidents of UAS involving Airbus aircraft, responses to UAS at cruise speed and altitude varied considerably, but no end results duplicated AF447, somehow they figured it all out successfully. I think you would agree, far more time in training and subsequent examination has been spent on critical low level UAS memory list possibilities, than on high altitude high speed UAS possibilities. Hopefully that has changed, AF447 being a lesson learned.

some of us used to make it a private requirement using spare time during an endorsement to ensure that pilots could handle several of the unlikely but very high risk scenarios

Yes, we could ask to, after check ride was over to do something not required with time left over to see how it worked out in the sim. I was flying into Caribbean islands with a lot of birds in a B727 at the time so asked to have two engines fail at 500 ft at V2+15 and the check airman said it wouldn't fly. I asked to try it anyway so he did and guess what, if flew. We had to descend about 200 ft to get to clean climb speed and climbed on one engine. We are usually over water so ground effect wasn't even needed to not have to ditch.

Using the sim is a great way to try not normally trained methods of surviving.

Since stall AOA varies with Mach No., and the ADRs requires >60 knots dynamic pressure to have a valid (i.e. 'acceptable' airspeed value), the aircraft had no way to calculate the stall AOA using the available data when the AOA got so high that the pitot tubes could not work. It could calculate the AOA, just not what the stall AOA was and thus, it could not provide a warning.

The programming was inadequate for this condition of being airborne with very high AOA.

There are a number of things that could have been done to determine how much stall AOA correction for Mach was necessary, but since it wasn't written into the code, it didn't happen.

If, for example, the aircraft could compare g to measured AOA, it should then have been possible to estimate IAS with sufficient accuracy to set flight control gains as well as estimating Mach number based on OAT and altitude.

In any case, when NCD was encountered while airborne, the stall warning AOA should have at least been set to the backup value of 8.6 degrees and not just turned off simply because the airspeed didn't make sense. See Hazlenut's post for additional data. http://www.pprune.org/7210355-post943.html

I'll imagine that we will hear from Dozy on this.:}

C'mon, 'bird.

As you and I and Retired have said, the AoA vanes/cones should be taken as gospel unless they are all in disagreement or some other criteria is applied, and CAS isn't one of them.

The simple fact is that the 'bus control law reversion logic is complicated and has a plethora of modes and sub-modes and......... Sheesh.

AoA should be the primary "protection" according to the jet's aero capabilities. I have no problem with the 'bus "gee" implementation due to its mission. The fact is that planes fly using lift by wings that can produce whatever at whatever AoA. So the 'bus might use a law resembling ours that limited commanded gee versus AoA. Take our law and divide by 8 gees and you have it.

Make no mistake, I do not like a "direct" control law for the heavies due to many technical and aero reasons. If you have a FBW system, then you use whatever still works to fly the plane as the old ones used to fly. You don't have force feedback, but you can sense rates and gees. The planes since the mid-50's had hydraulics and a few direct mechanical connects to the control surfaces. They have not been like an Aeronica or Chipmunk since then, so enough of this macho direct control stuff. My ilk flew most of the time in pure "manual" with hydraulic valves at the base of the stick. No mechanical connections of any kind to flaps or spoilers or anything. We done just fine. And then came along fly-by-wire, and I was one of the initial cadre.

Glad to have a "final" few posts to get some things off our chests.

Hi Gums,
Just 'cause there isn't an AOA gauge for the pilots doesn't mean that the aircraft doesn't know what value it is. All we need to do is instruct the aircraft properly what to do with the AOA data when it's usual stuff like airspeed starts to drop off the line.

The problem seems to be that the engineers have been thinking in terms of airspeed and not in terms of it's alter ego, AOA.

You know how to fly an aircraft using just AOA and so do I, but for some reason they didn't tell F-GZCP how to do it.:{

Perhaps a Dumb Question
 

Apologies if this has been covered previously - I really have little to add to the discussion that isn't rather biased - but I'm curious.

How does Airbus enunciate stall warning? I'm thinking a 'stick shaker' type alert isn't consistent with the side stick controller, so is some sort of verbal "STALL"? :uhoh:
I know there have been accidents in the past where the flight crew - when confronted with a stick shaker combined with UAS - apparently concluded it was Mach buffet and continued to do the wrong thing. I'm trying to understand how this flight crew could have dismissed a stall warning (even if it subsequently went away). Hence am curious on how that warning gets enunciated.

tdracer,

the stall warning is a synthetic voice shouting "STALL","STALL","STALL" followed by an irritating "cricket" noise. It 'goes away' whenever the AoA is greater than 42.5 degrees.

IMHO one has to be unrealistically optimistic to believe that this crew would have been able to recover from an AoA greater than 42.5 degrees, even if the controllability of the airplane would theoretically have allowed it.

But then I hasten to add that I'm not a pilot.

I guess if you are at 38,000 feet and keep hearing stall, stall, stall and you keep pulling back on the stick on any airplane and fall into the ocean with the controls full back all aircraft will do what AF447 did and all will die.

HazelNuts39, Having diligently piloted the aircraft to this unrealistic attitude, I doubt even that particular crew (if they could) would argue that point.:\;)

@machinbird

Yes that must be true. It is a case where the "requisite imagination" failed to envisage such a case as a necessary condition. But if some engineer had dared to suggest before publication of the AF447 DFDR traces that the aircraft might be driven into a 42 deg plus AoA situation and held there by pilot action they would have been howled down with scornful cries of "You are not a pilot" and "No pilot would do such a thing". I find it difficult to accept that the designers and their test pilot colleagues acting ten years earlier would have any reason to conclude differently.

As you say, it wasn't written into the code so it didn't happen, but it is not obvious that it needs to happen. If you are at 45 deg AoA or more it hardly matters whether the threshold for warning is 8.6 deg or 17.2 deg. The warning should be sounding.

I think you are missing a point however. If the warning were to be latched until safe conditions were restored (as suggested by BOAC and myself) the airspeed indications would necessarily be restored to normal and the proper stall warning threshold for the Mach number computed before the warning would be cancelled. You will remember that when the AoA was reduced temporarily the airspeed came back on line and the stall warning with it. That is why I think your next suggestion -
is an unnecessary complication.


Yes I agree with you there.

Sorry Chris, but the likes of Owain Glyndwr have no explanation other than the obvious; that the logic designed to protect against stall at low Mach numbers had unexpected side effects when applied at high Mach numbers.

The low speed logic is not stupid. If the system has reason to expect that stall AoA might be reached in a short time if current trends continue then it puts the aircraft into a temporary protection mode. If the pilot genuinely wants more AoA then it is available by moving the sidestick back. Otherwise the protection can be removed and the aircraft returned to "normal" behaviour by moving the stick forward. [Looking carefully at a digitised version of the traces it looks as if the "short time" is about 1.5 seconds]

In this particular case the autopilot dropped out because of a strong temperature shear (not the windshear you suggest). I personally suspect that designers do not currently give enough attention to temperature shifts, perhaps because they are not specified in FARs or CS25. On Concorde, which was designed against its own special (and generally more severe) rule book, we had to consider temperature changes of up to 21 deg C in one mile. This A340 incident was only 10 deg C in that distance.

Just after the A/P dropped out the aircraft met some reasonably strong turbulence. Again not extreme; working from the normal acceleration record one might deduce gusts of up to 15 fps (EAS) which is just under half the design gust for those altitudes. However, some of those gusts were sharp edged, so the rate of change of AoA was high. The actual AoA remained well below the deterrent buffet stall level - round about 2 deg below the Vs1g level, but the predicted AoA for 1.5 secs later went over the stall limit and triggered the alphaprotect mode.

Accepting that the subsequent motion was unexpected, it was not IMHO intrinsically unsafe. This was not an embryo AF447. The EFCS was, after all, acting to prevent a stall. There were no injuries and no aircraft damage. Dare I say that were it not for the proximity of the A330 and consequent possibility of a midair collision this incident would not have received the attention it has had. That seems to me an ATC problem and I note that the AIB made two ATC recommendations but nothing on the airplane.

DonH

As a retired designer, I have to agree with your assessment here. In order to design an aircraft one has to make certain assumptions. One of those is that the pilots will fly like - errr well like pilots actually ;)

One assumes that flying to respect the techniques and limits prescribed for the airplane will be the norm, but one must also recognise that techniques will not be followed exactly and limits not strictly respected. The problem is to know, or guess, the magnitude of these deviations that must be safely available.

Would you, for example, have predicted the AF447 actions? Or would you have imagined, when designing the autobrake logic that an aircraft might be landed on a flooded runway, with worn tyres, 29 kts above Vref in a 15 kt tailwind and put down with a long flare?

It is always easier to make these flights of imagination with hindsight :ouch:

Quote from Owen Glyndwr (my underscoring):
In this particular case the autopilot dropped out because of a strong temperature shear (not the windshear you suggest).

Whoops! :{ Thanks for the reminder that the sudden increase in Mach to beyond Mmo was due to the sudden fall in temperature, not a headwind shear.

Quote:
...the logic designed to protect against stall at low Mach numbers had unexpected side effects when applied at high Mach numbers.

It's the logic at low Mach numbers that I'm questioning. As I wrote:
on the face of it, it seems bizarre for the FBW to "grab" a transient, higher-than-normal AoA even if it results in more than 1G with a neutral sidestick (assuming wings level).

Here's the best scenario I can think of at the moment. I'm hand-flying at low altitude in the holding stack and there's a severe, momentary up-gust, causing a momentary (rapid) rise in AoA towards alpha-prot.

Phase-advanced alpha-protection puts the FBW into AoA Protection Law. Meanwhile, the AoA has returned (fallen) to what it was before the gust. However, FBW uses up-elevator to increase the AoA to alpha-prot. The a/c climbs suddenly until I push the stick forward more than half-travel, OR use less-than-half forward stick for more than a second.

Although I'm unlikely to allow the a/c to climb much (unless I'm having a bad day at the office, or get distracted), maintaining AoA Law seems an unnecessary presumption by the FBW.

So my question remains: why does it not revert to Normal Law once the AoA falls to a safe value?

Hang on a minute! Suppose it is an A320 at say 60 tonnes - holding at 200 kts?
That will be about 5.5 deg AoA with stall at 12 deg. The alphaprotect logic is a combination of alpha and rate of change of alpha, but take just alpha for the moment. You are going to need a gust of 38 fps to get to the stall and from published A320 flight statistics you will need to fly half a million flight hours at 200 kts before you hit that sort of gust. OK one needs to back off a bit to account for the phase advance contribution, but it will still be a helluva lot of hours :=

So in theory you may be right about the possibility but it would be an extremely rare case I think.

As for why it doesn't revert to normal law, surely it cannot, because once alphaprotect has taken charge the AOA is held at the alphaprotect value?

Re: 330, 340 near miss not AF447
 

Another question for OG,

I'm still struggling with the contents of the AAIB bulletin concerning the 330 & 340 near miss....

....specifically the 340 Captain's statement that he observed an 'alpha lock' message and then the board's conclusion that it was probably an 'alpha floor' annunciation when under the circumstances, the lowest IAS & IMN stated as 205 & 0.67, it seems highly likely that neither of these messages would or even could be displayed.

Why would the board glom onto 'alpha floor' as a probable when it's inhibited above 0.53 IMN?

What am I missing here? Has someone else covered this earlier?

@OK465
The straight answer is that I don't know :O Partly because I'm not sure what "alpha lock" entails and partly because the recorded behaviour of the engines is consistent with an 'alphafloor' occurrence regardless of what the book says said about its 0.53M threshold.
The AIB report text is:
Its all a bit confusing, as the thrust increase came at about the same time, or even a little after, the A/T was disconnected, but the report makes no mention of any throttle increase by the PF, only the thrust reduction. Also the phraseology "if airspeed is likely to reduce to a value approaching alpha max" leaves one wondering! It does imply though that alpha floor switching is also a function of rate of change (of speed?)

Ducking the issue somewhat, I imagine that the AIB will have taken advice from Airbus on what might have been and I would think (well hope anyway) that AI would understand their own system :ok:

Edit: OK I now understand what alpha lock is, (prohibiting slat retraction in certain circumstances) but so far as I can see it would in no way be relevant to the cruise condition where this incident occurred.

Thanks OG,

Just an observation....

....if done as a demo or ops check in a level D FFS, using idle thrust just to expedite a level entry from say a weight dependent ~200 KCAS at FL350 into AOA protection, hands-off it will drift on down at alpha prot no thrust increase, if the SS is cycled full aft aggressively to achieve a short term transient alpha max there is still no thrust increase....

Like clockwork at around Fl280 (0.53 IMN) thrust comes up and alpha floor is then annunciated.

But it is only a sim, and real air can do some strange things. :)

I agree it is unlikely it was an SFCC alpha lock indication, I believe that is annunciated by the slat/flap indicator display anyway (don't recall for sure).

It's just the word probably that is intriguing and the fact that the Captain would have had to take positive action to exit alpha floor and one would think observe the alpha floor annunciation extinguish. Of course he was 60 years old and I noticed myself that at that point my powers of observation were waning somewhat also. :}

Quotes from Owain Glyndwr:

"Hang on a minute! Suppose it is an A320 at say 60 tonnes - holding at 200 kts? That will be about 5.5 deg AoA with stall at 12 deg."

Yes, Owain, that's very much the speed I would expect for holding an A320 (clean) at 60T - "Green Dot" speed would be 205, which is well above VLS, and the FMGC sometimes suggests a slightly lower figure than Green Dot for holding. A level-flight pitch of about +5 or so is typical, suggesting an AoA of that value. You quote an AoA of "stall at 12 deg". Bearing in mind that AoA Protection Law is based on alpha-prot, is that figure alpha-prot, or alpha-max? (I presume the former.)

"The alphaprotect logic is a combination of alpha and rate of change of alpha, but take just alpha for the moment. You are going to need a gust of 38 fps to get to the stall..."

Agree that a sudden up-gust of 38 fps (2280 fpm) must be extremely rare, but you admit that 38 fps doesn't take phase-advance into account.

"As for why it doesn't revert to normal law, surely it cannot, because once alphaprotect has taken charge the AOA is held at the alphaprotect value?"

...Precisely the logic I'm calling into question! :ok:

No, that is stall for a completely clean airframe (slats and flaps retracted) at low Mach No.

That is a very intriguing question. I would love to know the answer to that.

Probably to prevent osicillations between NORMAL and AoA Law, so it needs a positive ND SS input to revert to NORMAL Law.

A33Zab
Now that sounds a very sensible answer :ok:

And lest we forget, when talking about the airprox incident (as opposed to AF447) - I think it would be wise to remember - before getting tied up in suggesting problems with the systems - that all the crew had to do, both to arrest the climb and exit the AoA/Alpha Prot mode, was to *push forward on the stick*. Hardly rocket science and, by my estimation, fairly intuitive piloting** - no?

Of course, the same held true in many ways for AF447. I continue to believe that the Stall Warning issue is to some extent a red herring in the grand scheme of things, because the thing was working fine for more than enough time to have been picked up by the crew before the aircraft and its sensors went too far into the unknown.

Also, I'm still seeing references to "automation-dependent crew", which as I said before doesn't square with the sailplane qualifications of the AF447 PF - there is no automation (or for that matter TOGA power) on a glider!

** - In the sense that whether you're flying anything from a Cessna to Concorde, if the aircraft isn't pointing where you want it to go - point it where you want it to go!

@Dozy
Which is what they did of course!

@Chris Scott
Reason for that is that with the pretty well universal right handed system of axes used to describe airplane motions a clockwise (nose up, tail down) rotation is positive. That means that 'down' elevator is positive. Although the RHS axes don't have to be applied inside the aircraft it makes sense to have a positive (forward) movement of the stick correspond to a positive (downwards) elevator movement.

Agreed, although it is definitely concerning that it didn't occur to them until they'd already busted their flight level.

A340 AIRPROX Alpha-Floor
 

Quote from Owain Glyndwr:
"...the recorded behaviour of the engines is consistent with an 'alphafloor' occurrence regardless of what the book says said about its 0.53M threshold... ...the thrust increase came at about the same time, or even a little after, the A/T was disconnected, but the report makes no mention of any throttle increase by the PF..."

I can't shed any light on the alleged (by OK465) maximum of M0.53 for Alpha-Floor initiation. Just in case there's any misunderstanding, however, my recollection is that Alpha-Floor itself engages A/THR if the latter is currently OFF, regardless of thrust-lever position.

@Chris Scott:

If I recall correctly the Alpha Floor functions with A/THR OFF, but it will not function if A/THR is *disabled*, if not in Normal Law, or below 100ft RA. I'm not sure about the Mach limit** - OK465, would you have a reference handy?

One thing that struck me when I read the airprox report was that the A340 Captain said he noted "ALPHA LOCK" on his PFD, which the AAIB took as a misreading of "A. FLOOR". The thought occurred to me that it might possibly have been a misread of ALPHA PROT (from the transient AoA anomaly) and THR. LOCK (from the AP disconnect). Just a thought...

** - I should note however, that in my experience OK465 is usually correct! :ok:

Well that would clear up one mystery!

Here we go again
 

Salute!

Fer chrissakes, we are back to the basic design and such of the magenta line jets and the associated autopilot modes and their connection with the FBW systems or even the old systems.

I simply cannot understand the rationale of all the sub-modes of the FLCS ( flight control system) and the autopilot (AP) connections and on and on. Good grief!!!

I do understand that the heavies appreciate some of the AP modes and such to reduce workload and so forth. Funny for me, as I was the only guy in the jet and didn't have a PNF or anyone but Otto to help.

I must insist upon iterating my view of the Viper's FBW contol laws and some of the logic behind the design. This is compared to the 'bus design and more importantly, the implementation. I feel that most of the old school farts here would have liked what I flew with 35 yerars ago.

I cannot understand an implementation that switches modes and laws and such based upon "noise level" variations in temperature or mach changes or whatever. This is especially true for the heavies, that have basic inertial flight paths like most objects zooming thru the air, and lots more inertia than I ever had. And then there's the connect with nav systems and AP functions and on and on and on.

It all came down to AoA for we Viper pilots. Our FLCS trusted the AoA vanes all the way unless deemed FUBAR for a few seconds. I once went vertical and was looking over my shoulder when the "slow speed horn" sounded. "Gums, you are below 120 knots and gear is up!" OK, let go of the sidestick and let HAL do what it can do. So came back down in a tailslide and all the FLCS warning lights came on, Master Caution light came on, and so forth. Jet pitched down and I didn't touch a thing and forced myself not to pull back or forward. A few seconds later I was flying again and reset all the stuff and the fight was still on.

I realize that the heavy pilots here don't have those situations, but they sure as hell have some situations that require basic airmanship and a complete understanding of all the capabilities of their plane and maybe even all the modes and sub-modes of all the the FLCS and the AP modes and so forth. I empathize with them.

'nuf philosophy from this old FBW pioneer.

@gums:

You must know by now that I have the deepest respect for you. That said, you're not really saying anything you haven't said before. We covered the rationale behind the law changes repeatedly long ago - if you don't like it, that's all good, but it doesn't make the implementation bad.

Well yes, because it was a fighter and the expected operating parameter ranges of those AoA vanes was significantly different. The current flight control law has absolutely no effect on the validity of data from the AoA vanes on the A330, so I'm at somewhat of a loss to understand the point you're making.

But OWAIN, if you can still set the gains for the flight control system, do you need to drop out of Normal Law in the first place?
I don't believe that the accuracy would be sufficient to manage an auto throttle system, but it should be possible to calculate gain settings that would permit Normal Law or perhaps a variant of Alternate 1 Law. Any improvement in stall warning calculation is just icing on the cake.

For us non Airbus pilots that don't really care if the autopilot or autothrottle even works because we don't rely on them at all why is automation so important to Airbus pilots and how can it be blamed for any crash? We like to let it relieve our work load but if it quits we just hand fly. If the IAS goes away on all three air speed indicators we fly attitude and power using a QRH. We don't have to know any laws. We are either in automatic or manual. One is a little more work but no big deal. I don't get it.