Something like this saying Mayday accomplishes absolutly nothing. I would only say Mayday or declare an emergency if I would get preferential handling, not because my wing fell off and nobody could help me anyway. What's the point?

bubbers44 Something like this saying Mayday accomplishes absolutly nothing. I would only say Mayday or declare an emergency if I would get preferential handling, not because my wing fell off and nobody could help me anyway. What's the point?

Well, that's you, bub, and they may have considered a MAYDAY "not relevant to the flight", just like BEA may have, and that may be why we do not see it reported. There were several flights in the area, and they had radio access to these crews, to report trouble. If their radios worked. We see almost nothing of what adds up to an absolutely bizarre absence of acknowledgement of their situation. Whether the astonishing lack of chatter in the cockpit, the lack of radio, and the lack of TCAS, something is not adding up.

Take stock of all that is missing, and remember that BEA have purposely and admittedly omitted data. How much? Unknown. What type? Unknown. Initially the BEA stated the RHS was not recorded on the FDR, yet later we see A//P 2 trace, and stick, etc. What about radios, and the initial MEL re comms2? Cockpit heating, wipers, cargo hold temp, RHS NAV/RADAR 2, and FD2 traces? Which Buss carries RHS data to FDR? How did it not get recorded, then simply appear?
Plus all other parameters. What is up with that? The report claims AP2 was recorded, does that mean 'NOT engaged'? Or OFF? Because Captain told us it was selected ON...it may not matter re: flight path, and at the time, recovery was not possible. What it shows is a couple of disconnects in the report?

Bubbers44
 

Well, how about a lengthened version in that case? :
"CAUTION. Flying debris coming to a flight level near you!"? :eek:

You misinterpreted the statement. It was the RHS *display* that was not recorded, not the RHS information as a whole.

I'd be prepared to wager a considerable amount that the only data not in the report is the data considered irrelevant. Given that there's a plethora of data available in the report (certainly more than I've seen in previous reports from the NTSB, AAIB and - indeed - earlier BEA reports), I can't see why you're convinced something's being hidden.

" I can't see why you're convinced something's being hidden."

But much is "hidden", Doze. I propose that much of it is appropriately invisible, but it is a matter of conjecture what relevance it may have.

You are mistaken about the displays being not recorded. The Captain is recorded telling us the AUTOPILOT annunciator is on the screen....Everything was not recorded does not mean the panel was compromised, or replete with dangerous and erroneous data. It simply "was not recorded"

You don't think like I do, Doze, but you may want to count yourself well off in that regard. I spent a year working for the Government, investigating....the Government. I am a trusting and forgiving person at heart, but if I sniff bull !!!!, and the presence of said bs is meant to fool people, I get right nosy, and persistent.

Really? I must have missed that - I read he was heard to confirm and make sure it was off, but maybe you have different data to me.

[EDIT : Confirmed - FDR shows both AP off from initial disengagement to impact.]

Except for the sound of the selector on the CAM.

A sister ship to the 330 had an electrical short circuit in flight, and the crew lost half of their ECAM, lost Navigation, had cockpit cabin communication failure, and lost effective control of the stick, along with autopilot.

Any of this sound familiar?

Would you like to read the serious incident report?

At that point it was just belt-and-braces to make sure it's off. Unlike the FD there is a distinct and specific FDR trace for AP disengagement and it remains OFF throughout the sequence.

It's possible that the Captain had fallen back to a mental mode where he was attempting checklists by rote and simply double-checking all of the points he could remember. Perhaps he was disorientated and misidentified the selector.

In any case as far as the aircraft systems were concerned, the AP was OFF and stayed off.

As to your other points, AF is not a state airline and Airbus is not a state institution. They are both commercial entities in which the French government has a stake - nothing more, nothing less. Hiding problems will always be a self-defeating action - McDonnell Douglas learned that lesson the hard way, and you can bet the French government took notice because the tragedy that brought the secrecy to light happened on their soil. All claims of cover-up and skullduggery on the part of the French regarding Airbus can be traced directly to a single incident where lawyers acting for a defendant in the case leaked unsubstantiated scuttlebutt to the press, who repeated it unchallenged.

But here we have hard evidence that at least one display was functioning correctly, and no instrumentation other than airspeed was lost. You're trying to draw a false equivalency.

I don't think flight 447 was concerned about a mayday call to warn flights below them at that moment. Would you? Mayday will give you priority but over the Atlantic what does it accomplish, nothing.

Notifying adjacent traffic would accomplish reporting at least, You might be right, they had their hands full, and they may well have decided to remain anonymous. Screwing the Poodle is embarrassing for the French?

I do agree on that.
That being said, the 12 degrees of pitch was absolutely undesirable, but was not fatal. Some 40 sec after AP disc the situation was borderline but had stopped to deteriorate ... until the FD reappeared and the PF got the bad reflex to follow them. That's when everything took the wrong turn and STALL2 arrived.

Now, that's also the precise moment the trim started to roll ...
It is absolutely unprofessional for the BEA to have omitted to include the full analysis on that matter in their final report.

No misplaced autotrim, and 'we wouldnt' be discussing an accident here'.

Without autotrim, the PF would have pulled more to follow the FD, or to maintain 15°, or 12.5° pitch, or to arrest the V/S.

Not to mention that the autotrim does not and did not move of its own volition, but moved in response to the consistent and excessive (for the conditions) backpressure on the stick from the PF.

The fact that the A320 seems to have a hard limit on autotrim in Alternate whereas the A330 does not is an interesting line of discussion, but it's not really a subject within the scope of the report.

Hi DozyWannabe,
autotrim will move the stabiliser without any input from PF. If the speed of the aircraft changes, then the trim will run to help the elevator.

Once PF had commanded a pitch attitude which resulted in a real (not just spuriously indicated) speed decay - even if he didn't touch the side stick again - the FBW computers would attempt to maintain that trajectory by moving the elevators and hence the stab trim.

Agreed. But the culprit is not autotrim, without it the airplane would still have stalled.

That´s DozyW´s Oozlum bird. Either you don´t understand the system in the respective Alt2 Law or you don´t want to know.

Without autotrim only the elevators (already in full NU position by the FCS in an attempt to maintain the trajectory while airspeed decaying) would have been available for SS inputs. Then a further nose up command wouldn´t have changed anything. Although there are no data available (as BEA didn´t discuss that matter in the report) it must be assumed, that the pullup would have been terminated earlier with a higher speed. Without autotrim the mentioned neutral stability (mentioned by BEA) could have not be maintained and a significant nosedrop would have been present.

We still don´t know if it would have saved the day though.
If talking about culprit then the law reversion logic comes into my mind. Unlimited Autotrim in ALT2b in conjunction with only BIO-protection seems not a clever idea. Why was the limit of the autotrim in Alt law out-designed in the A330/340 and not retained like in the 320 series? What kind of situation would necessitate an full up THS when careful handling due to the law degradation is necessary?

For BEA the case looks like lost after the aircraft departed the flight envelope. Does that mean, that there was no chance of recovery or that they didn´t look into that matter? THS position and autotrim would play a role when looking into that phase of the flight.

The movement of the elevator and THS in response to sidestick commands is defined by the system and was determined until the end of the flight. The aerodynamic response of the airplane can only be simulated with any confidence within the known flight envelope.

HazelNuts39

Yes, the aircraft would have Stalled without Autotrim full up. But without the THS authority to keep the Nose Up at STALL, the aircraft's nose may have fallen through, instead of being maintained in the Mush...

No?

( sorry Franzl, missed your post, but it bears repeating, imo)

Maybe slightly but, IMHO, with full nose-up elevator maintained, not enough to unstall the airplane. I don't expect the airplane to have the straight-wing characteristic of a nose drop that can't be arrested.

Who would know re: neutral airframe, with the Autotrim busting a gut to keep the flight Path, ?

I don't think the A330 was tested at STALL with full nose up trim? Who would have the balls to do that? And if the a/c can get to STALL by having the flight path seeking it, why isn't the a/c in DIRECT at this point?

If AUTO STALL is available, let's test it in the certs. And at least consider that some additional cue might be helpful...

Lyman, I'd like to revisit a fundamental task drilled into pilots from formative days, formative hours. This is in reference to the "mayday call" idea and what raises or lowers the nose.

The fundamental? Aviate. Navigate. Communicate. Given the trouble with the first, any pretense that the last -- calling Mayday or whatever -- has any importance is incorrect.

Aviate.

Pilots are (or should) control the aircraft. If it does X, and X isn't what should be happening, the pilot, using the systems at his disposal, makes it do something else. That is the premise of "controlled flight" versus "uncontrolled flight" or even "passenger in the very front seat."

While the THS certainly helps find a pitch attitude commanded by the system, there is a certain monotony to repeating again and again that the pilots inputs are part of the system. Based on what the FDR data found, the input from the SS was not cut out leaving the pilot at the mercy of the robot.

Why the pilot at the controls kept the nose up is in part (in my mind) explained by the idea that he latched onto the FD as a primary scan item, rather than flying a more primative scan based upon attitude indicator (artificial horizon if you like) compared to other instruments, which takes us back to opinions rendered here on PPRuNe while the BEA were still trying to find the wreckage site deep in the Atlantic Ocean: the Pitch and Power chorus will once again seranade us, since pitch and power comprise fundamental concerns of the fundamental number 1 noted above.

Aviate. Why that broke down seems to have a far heavier HF component (culture, training, and more) than mechanical component, though the complaints on how nuanced the control laws can become in the variety of degraded modes seems to have some merit.

At four thousand feet, descending at 120 knots, I might consider a last will and testament, though a short one, an aural one, with a keyed mic.

Lonewolf. From the outset of the report of the loss of this a/c, I suspected the pilots were betrayed by the aircraft. I did not necessarily conclude they were without blame, but something did not add up. One of my hundred or so theories early on was that the crew followed the 'bird' into the drink. If ADR can fail, my mindset would be to fly, and trouble shoot. ANC is swell, but sometimes they get rearranged, and there was no teamwork here. I frankly did not suspect any, Teamwork is disincentivised when troubleshooting is trained to be snail paced, and recovering the flight path is URGENT.

Get out the freaking BOOK?

."what raises or lowers the nose."

You forget, the NOSE is secondary. What raises and lowers the tail is the deal.
My instructor told me to be aware of the cause, not the result. Looking at the nose instead of thinking about the tail?

Agreed.

Which was the point I was making. Autotrim was trying to compensate for the simultaneous fall-off in airspeed *and* the commanded nose-up attitude, both of which were directly attributable to the PF's backstick commands.

@franzl - If I had to guess, I'd say that the autotrim limitation might have been dropped for the widebodies due to criticism from some pilots over not having full authority through the PFCs in Alternate Law.

Quote:
Once PF had commanded a pitch attitude which resulted in a real (not just spuriously indicated) speed decay - even if he didn't touch the side stick again - the FBW computers would attempt to maintain that trajectory by moving the elevators and hence the stab trim.

Even if the pilot had let go the stick following his first input of NU, the a/c would have flown into STALL. This means the pilot is constantly responsible for Pitch, but cannot relax the stick either, setting up a lethal and terminal misunderstanding of flight path in an upset a/c. Peachy.

Alternate Law in upset is absurd. And deadly.

Lyman
Come on. Which end of the teeter totter is going up? Completely irrelevant point IMO.

Bear with me Commander, my teacher had an angle, and it served me well. Step back, and see if you do not agree. Airbus and aviation are dumbing down the pilot pool.

Jim G was a Naval Aviator. Corsairs. The ones with propellers. He taught me to constantly assess what the aircraft was doing, and the controls part in it. He may have said something like, " if you think something is wrong, it is. Otherwise you don't understand your airplane." He taught feel. If he hadn't flown his Baron into that building, he'd be all over this case.

(get home- itis.)

THS, one mo' time
 

Here's the snip from the FCOM I have been given from one of the pilots here:

http://www.sluf.org/misc_pages/a330_flight_mode.jpg

I can't find any clear reference to "auto-trim" until "Direct Law".

Note that the THS seems to follow pilot inputs except when AoA "protection" is active, and in our case HAL decided AoA was irrelevant. GASP!

Maybe A33Z can help here.

So I'll throw my vote in with several here that the THS auto-trim feature did not help the situation, and may have contributed to the stall entry and remaining in the stall unless the pilot commanded nose down/lower gee than "one".

I continue to iterate that the 'bus system is not an "attitude" command but a gee command. Because HAL corrects for pitch attitude, the basic one gee command is "corrected". So you think the jet is trying to maintain an attitude, but that's just a result of the corrected gee comand. Additionally, without auto-throttle, the only speed stability is when drag equals thrust, and it is not what we old dinosaurs were used to when the plane tried to achieve the trimmed AoA ( and resulting drag versus lift properties).

So way I read things, the plane would have trimmed for one gee corrected for 10 or 12 degrees pitch even if the pilot let go of the stick. The THS eventually reaches max and.........

Issue with BEA investigators is they had expert help at hand, they correctly understand how Airbus FBW works and are fully aware what "acceptable by certification authorities" means.

PPRuNers have no such resources readily available, therefore I find it unsurprising that some only slightly wrong theories about how Airbus FBW works resulted in quite flawed assumptions being passed as facts, leading to another oozlumistic round of suspicious glances being cast towards BEA, DGAC and Airbus.

Let's get to basics of aircraft stability: conventional certification rules state that no passenger transport aircraft will get certified unless she displays adequate static and dynamic stability in pitch. Static stability means aeroplane, when disturbed from trimmed speed, will return to it stick-free. Dynamic stability means it will do so in acceptable number of convergent oscillations. Stability is not just a matter of aerodynamics; control forces, controls architecture and power all affect it so it can be (and mostly is) significantly modified by FBW. FBW Airbi can not demonstrate hands-off stability in normal and alternate laws as due specific settings of their FBW they will not make an attempt to return to trimmed speed after the stick is released.

As for how Airbus FBW works, lets first start with how it doesn't. It was said it maintains 1g. It was said it maintains pitch. It was said it maintains alpha. In normal operation, none of this is true. It might maintain all three of it but not because it pursues them actively but only as a consequence of trying to maintain constant flightpath when stick is pitch neutral.

So how it works for the pilot? First we'll assume steady, level manual flight with ATHR in SPEED mode (to digress a bit: most of the world flies this way while my company was pretty adamant: manual flight - manual thrust, no matter if it is Boeing or Airbus or whatever). If there's moderate pull or push and then release to neutral, FBW will maintain new flightpath, autothrust will compensate with thrust change, aeroplane will feel pitch neutral. So far so good.

Now let's assume ATHR is off, aeroplane is flying straight&level and a couple of degrees of pitch up are introduced while thrust remains constant. Aeroplane tries to maintain the flightpath but as some power now has to be used to climb, drag causes the aeroplane to decelerate. As it decelerates, it needs more AoA to keep the fligtpath so FCS introduces a little more pitchup on its own. Aeroplane feels slightly unstable but if power and pitch are reasonable, equilibrium point where the new flightpath can be maintained without further increase in alpha is met. Still good.

If we take extreme case, where aeroplane is flying straight & level and TLs are moved to idle, aeroplane indeed starts to pitch up on her own as the speed is bled off. How long does it pitch-up? Until alpha prot activates in normal law, low speed stability kicks in in alternate1 and introduces pitch-down or it stalls in alternate2.

So why is it all so seemingly complicated? Simples. To make life easier for mister pilot and provide him with perfectly conventional control response within the envelope. There is absolutely no need to think about flightpath or trim. Stick forward moves nose down. Stick backward moves nose up. Stick left rolls the aeroplane left. No points for guessing what does stick right. Many a claim was made on this rumour network that oh-so-complicated-Airbus-took-the-controls-away-from-me-when-it-shouldn't-have. None of them were substantiated except St.Johns and Bilbao - that's fixed now.

While the nomenclature between SA and TA Airbi is different, principles of protections are pretty similar. We didn't call it ALT1 and ALT2 when I was on 319. Their rough equivalents are "alternate with reduced protections" and "alternate without protections" (nitpickers, welcome).

How do I know AF447 wasn't deep-stalled? Well, I started by paying attention in high school science classes, which helped me to understand aerodynamics lessons during my flight training. One of them involved deep stall and I learnt it has specific meaning: it is stall which cannot be recovered by conventional means such as actions on elevator, stabilizer or power. While AF447 never fully recovered, mere reduction of power or just moving the elevators towards the neutral (while never reaching it) abruptly decreased its AoA - which is incompatible with deep stall as we know it. Now if your goal is to be taken seriously in discussion, you won't go a long way if you take well established terms and start assigning them just your own definitions.

If it were true, then dr. Evil Genius who invented should be stripped off of his PhD! He has less than three percent success in catching the crews in his trap!

Seriously, these unsubstantiated claims are so repetitive I can't even find them humorous anymore.

Is it news for anyone else? :hmm:

Hollywood's bravo sierra. In their minds, crew was fighting for their lives until the end, there was no time for pathetic farewells. That they completely misunderstood their enemy and eventually committed the suicide by incompetence is tragic, not stupid.

Harsh words, but if we assume they're true then so were others. Difference is they choose more appropriate response, even if it meant doing nothing at all while been confused about what is happening.

Using brain instead of balls tends to produce better outcomes. Like not even trying what was computed to be fairly suicidal.

Looking into that matter could turn out to be very expensive... not just in Euros but also in lives.

No. Reference, please.

Glad I work for abnormal outfit.

Panic.

When ECAM works as designed and is faced with simple faults, it covers everything you need to know and do. No more, no less. No point putting "pretty please with sugar on top" on ECAM lines.

Yup. Proper flightpath control was never achieved and that always takes precedence over ECAM actions.

I suppose it is even more appropriate than you assume it is.

Perhaps it is leftover in our DNA from the times our ancestors were preyed upon by cave hyenas and short-faced bears but there are two main types of panicky reaction: getting frozen (maybe the hunter won't spot you if you don't move) or running away in whatever direction (this might help confuse the predator or make it catch someone slower). Seems to me that it was very unfortunate set of events that both pilots simultaneously fell victim to panic. CM2 was trying to run away from the danger he sensed was coming from below and had no understanding for the aeroplane's energy state while CM1 got too scared to intervene. IMHO another important aspect of your story is that your comrades, while doubtlessly well trained, were simultaneously faced with realization that they are not in training anymore, that (unlike drill sergeants who just play-pretend) folks out are there are really bent on killing them and that not everything is going according to the plan. Sudden realization of one's own mortality can easily set the atavistic instincts in motion.

Is it news for anyone else?

Clandestino. You have the luxury of your assumption that the pilot was a moron. Or that I am, or anyone else who thinks luxuries such as yours are Ill advised.

I meant that the pilot is responsible for constantly monitoring the stick as well as the plane. You ass ume he had full complement of displays, and was ignoring pitch, in favor of roll? These are easy peasy, not attested to by the report, and are frankly tiresome. Perhaps as tiresome as my insistence on reading more data?

In an upset, and without dependable instruments, my guess is your drawers would fill up. I truly appreciate your style, with some exceptions, but draw the line at your holier than thou nonsense.

the aircraft's nose may have fallen through,

HazelNuts, I did not mean the Nose would fall and everything was ducks, I meant that as one of only two airframe cues for STALL, it's lowering against the stick would have some warning value to the pilots, as intended in a normal aircraft.

Bear in mind even BEA had to ask experts if the accels in the DFDR traces were buffet, suggesting the pilots missed that one remaining cue, perhaps missing it in the turbulence.

In the approach to Stall recovery that is trained, the nose does not drop, so a non dropping nose and no buffet may have meant: " I knew it, that stupid Stall Warning was bs..."

I can't imagine how you were trained to recover from a stall warning without a briefing - but I'm glad you work for an abnormal outfit as well.

Really good post by the Cland
 

Very good post by Cland, and a lot of agreement from this old FBW pioneer.

I was particularly impressed by this snippet:

I would only point out that "stability" in the FBW jets is still a basic aero function of cee gee, center of aero pressure, moment arms and capability of the control surfaces, and on and on and on....

As Cland pointed out, what we see is "apparent" stability. The FBW system works to modify the inherent aero stability (or lack of) in order to provide the basic pilot a plane that he/she can fly. I had a chance to fly the AFTI sim ( modified Viper) and see various control laws that were enabled with the software. The body rate law was very foreign, and was quickly passed by. The attitude law was same same. The pure AoA-biased law felt really great for any old pilot. But the best law was one based upon a blended AoA-gee. Sheesh! It was close to the one that GD had come up with ten years before. The AoA limits helped to prevent stalls and such. The gee limits kept us from ripping the wings off.

Due to our mission requirements ( Doze will jump on this, heh heh) and our immense speed envelope, we did not require "speed protection". In fairness, we had one troop die when diving down at a speed beyond the placard value, but the airframe was solid and the motor exploded. Vne was 800 knots CAS or so, and low-speed warning was about 120 knots CAS, so see what I mean?

IMHO, the 'bus designers learned from us, and their overall concepts seem very reasonable and directly related to the mission of the jet. Only thing I would have balked about was the AoA role and the plethora of reversion sequences.

Cland's description of what the pilot sees and senses is spot on. We didn't have the auto-throttle feature, so our workload with the throttle was much higher than holding an attitude. We stabilized speed when the drag equaled the thrust.

PLZ remember that I abandoned the "deep stall" theory after a few documents were made available to me. Don't know how old Cland is, but my high school aero and the stuff I could read at the library didn't approach this characteristic of some planes. Wasn't until the 727 came out that we saw a discussion. I then flew the VooDoo about 6 or 7 years later and we had "pitch-up", but it was complete LOC and the jet did not remain fully stalled in any fashion. Sucker tumbled in pitch with a super roll/yaw component.

So 15 years later I flew a jet that had the classic "deep stall". Funny, but some of the entry maneuver had FBW control system aspects. The maneuver was exactly the same as AF447. Climb at a pitch attitude and power setting until the jet ran outta the air molecules required to get the nose down with full elevator deflection ( no THS, as we had the all-moving horizontal stabilizers). Super directional stability like the 'bus seems to have, and no large pitch changes - just a reasonable ride while the altimeter is unwinding at 10,000 feet per minute. Fortunately, we had a positive pitch moment at that combination of cee gee and AoA. Unfortunately, HAL was commanding nose down and the jet couldn't get there. So our wizards gave us "direct law" in pitch via a switch that would not even work unless HAL senses AoA above 30 degrees. It worked and we didn't lose a lotta jets.

Thanks, Cland, for a great post.

Agree...refreshing and well worth reading Clandestino, thanks.

For Lyman:
The stick.

If that isn't what's happening, you have a flight control problem when you are sitting in the cockpit.

Your Corsair veteran IP would have agreed.

Going back a couple of pages, to the discussion of the "startle factor".... we were told it is not so simple to include genuine fear in sim pratice...

I'm sure somebody has mentioned Ernest K Gann and his experience of an instrument approach on a nasty evening, with the captain lighting one match after another under his nose. Gann managed to maintain his concentration despite this insane behavior, which made him better able to deal with difficult situations.

I have been startled on a couple of occasions; my response was to keep calm and do nothing; controls still OK, loud bang turned out to be unrequested descent of the undercarriage and not a mid-air. In another case, lap strap out the door began a rattatat on the fuselage. In the third case, the glider on tow suddenly appeared beside me, instead of behind; in all cases doing nothing turned out to be the correct response. But believe me, I was startled alright!

Not at all - speed protections would be inappropriate on a fighter, not to mention an absolute pig to implement!

I'm sure they did, along with everyone else who'd tried it!

If you'd looked across the pond at around the same time you'd have seen it become a very big deal in the UK (home of the T-tail) just before then - the 727 owing more than a little debt to Boeing's visit to De Havilland during Trident development. To this day I think it's the only large US-made airliner with a T-tail - and thus susceptible to the full-blown deep stall phenomenon. Deep stalls had claimed the lives of several prominent British test pilots before the characteristics were fully understood.

That said, the original design for the 757 had a T-tail, and ironically it was British Airways' demand for a conventional empennage which changed that.

:ok:

PS. Lyman - he didn't call the pilot a moron, he said that the response to the situation was incompetent. The former is a personal insult whereas the latter is a tragic fact - it's important to be aware of the difference.

If you light a match in modern simulators, it will set off the fire suppression system.

Indeed ... it's politically or diplomatically correct ....
But what do you think (first thinkink) about people who are making incompetent decision ?
They are "moron" ... or "smart" people ?
So I understand that Lyman can use the word "moron"