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Hi,
the nose down command was shorter; - the THS moved slightly but the BEA report does not mention it; - flight law was not alternate law; direct? abnormal? sub-variant of alternate? - there was a trim malfunction (but it seems unlikely that the BEA report does not mention it at this stage, so I rule this one out) Sorry but if what you tell is right .. the PNF is an idiot ! In the BEA report PNF announce "Alternate law" - the THS moved slightly but the BEA report does not mention it; THS moved slightly but BEA does not mention it ?Can you explain (if BEA not mention it) how you know it moved ? We can happily continue to speculate for months :8... as the final report will maybe show next year .... I can even speculate on the PF experience. .... The PF experience as nothing to do with the accident .. it's not a reference. Pilots on the Perpignan A320 XL crash had 7.000 hours and 5.500 hours on type ... :eek: Teneriffe KLM B747 ... the best KLM pilot was PF :eek: |
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We don't know if the ND picture was normal - until we know the tilt setting on the WXR it's difficult to conclude anything, but, I think At the time the FCTM/FCOM says something like" CRZ ALT - set tilt "slightly" negatively down," if that's what actually was set they may have been over scanning and had a false picture. Over water ITCZ type flying needs aggressive down tilts and short ranges(80nm and 3.5 ish down tilt etc)
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fgrieu, I think you'll find the A/C was in Alt Law 1 or 2 depending if it had concluded a ADR disagree or fault, either way the pitch control in Alt law 1 or 2 is the same, with normal THS movement dependent on the load factor command from the sidestick deflection.
Once the A/C exceeded 30 degrees AOA however the abnormal attitude would have kicked in remaining in ALT law however the THS auto trim would have stopped. So the initial nose up inputs caused the THS to trim for the new commanded load factor from the sidestick deflection (full nose up at times) and frozen at 13 degrees probably when the AOA exceeded 30 degrees. |
The PF experience has nothing to do with the accident .. it's not a reference. |
SMOC - have a look at #1242?
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Suggest a
"LAWS of TOULOUSE" become a sticky. :ugh: ( Laws of "too loose"? ) |
BOAC, I read that article again, and it seems to be contradictory.
{AF 447} After stalling, the A330's angle of attack stayed above 35°. But while this exceeded the threshold for the abnormal attitude law, the flight control computers had already rejected all three air data reference units and all air data parameters owing to discrepancy in the airspeed measurements. {My thought: does this mean that AoA greater than 30 deg does not trigger Abnormal Law, or that there are some more tie ins to the comparisons {summed inputs into the flight computer} requiring (valid?) airspeed input before that law is selected?} Abnormal law could only have been triggered by an inertial upset, such as a 50° pitch-up or bank angle of more than 125°. "That never occurred," says French accident investigation agency Bureau d'Enquetes et d'Analyses. The BEA is still attempting to explain why AF447's crew failed to rescue the aircraft after it climbed to 38,000ft and stalled. The pilot's control inputs were primarily nose-up, despite the stall condition. There has been no indication that the aircraft switched into any other control law, other than alternate, during the accident - suggesting that auto-trim was available throughout the descent. {skip a bit} In its conclusions over the {Perpignan} accident the BEA highlighted the rarity of the need to trim manually, which created a "habit" of having auto-trim available made it "difficult to return to flying with manual trimming". "One of the only circumstances in which a pilot can be confronted with the manual utilisation of the trim wheel is during simulator training," it said. "However, in this case, the exercises generally start in stabilised situations." In the wake of the A320 accident, near Perpignan in November 2008, the BEA recommended that safety regulators and manufacturers work to improve training and techniques for approach-to-stall situations, to ensure control of an aircraft in the pitch axis. |
So auto-trim was still active throughout the stall and continued stick-down inputs, had they been applied, would have moved the THS down and thus aided the recovery?
@Lonewolf: my reading of this, and the BEA report, is that the AOA data is lumped together with other air data measurements and accepted or ignored together... either all or none. (thoughts... does this apply to altitude and ROC too?) No abnormal law for the same reason as no stall warning. |
fgrieu -- note that the expert is said to be an ex-airbus pilot. When listening to the testimony of experts who have had previous links with manufacturers or employers, one should be sure to check that there is no axe to grind. Even a small chip on a shoulder can cause a man to walk with a pronounced limp. Demanding the entire fleet to be grounded until the phenomenon is 'adequately explained' (to whom?) is a serious step that could financially cripple or even destroy the manufacturers, airlines and their employees.
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Lonewolf - as we are plagued by two similar threads here, you should know I have queried this statement on the 'other'.
EDIT: Just seen your post! |
I completely agree with you Lemain!
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Lemain We have been here before
BBC ON THIS DAY | 10 | 1954: Comet jet crashes with 35 on board
Tinker at the edges until there is another crash into the sea? :uhoh: |
Lemain
Oh yeah. After BA038, there was a similar refrain. Two rollbacks, simultaneous on a twin. A somewhat more serious event than UAS? UAL recalled its entire fleet, but supposedly, for a deferred item (firebottle #5 in the Hold), then released them to the line after the inspex. Huttig plus salt shaker, please. (Chip on shoulder equals "limp" priceless!) |
In answer to Lemain:
I am just trying to understand what happened, and what lessons can be learned. I did link to an article echoing a voice asking to ground the planes, but that's not an endorsement of that opinion. If (that's far from evident, at least to me) the THS remained nose up 13° despite the pilot commanding a nose down circa 13000 ft due to a characteristic of the flight law then active, then I think pilots on the type should be trained to trim manually in order to get out of stall in that flight law, rather sooner than later. Anyway, if that's true, I expect many if not most pilots on the type have read the BEA report and came to that conclusion by themselves. Full disclosure: I'm not a pilot, I am an engineer working on security (not safety) critical systems. |
there is a lot of stuff left to cover by the BEA...... they have barely addressed the cockpit conversation, they have not addressed at all many of the ACARS messages that were sent during the last four minutes (PRIM1/SEC1 faults et al)
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I would say that in hindsight we all know that they should have stay clear of the ITCZ weather; well in that part of the world they could have deviated a hundred miles off course with no problem from ATC with respect to parallel airways.
However in the Atlantic or Pacific with closely spaced airways and random tracks, sometimes ATC is pretty slow or outright deny any request to deviate. I guess the junior crew members were reluctant to exercise the emegency option of deviating without clearance. Some airlines come down hard on pilots deviating without clearances. You may say, ask for deviation clearance early, but with the modern flat plate weather radar system, severe weather returns sometimes only pop up within 40-60 miles ahead. ATC like Tokyo takes hours to reply or authorise deviations. How do you veterans deal with this situation........exercise your emergency contigency procedures and deviate without clearance and risk a TCAS event followed by loads of explaining to do? |
BOAC, cheers, what are the odds, a failure allows the THS to still be used and unfortunately for whatever reason a significant nose down input is not made.
Perhaps Airbus should freeze the THS after an ADR failure and not wait until an abnormal attitude is reached leaving you with an A/C that is possibly trimmed just outside the range of a UA. |
BOAC, cheers, what are the odds, a failure allows the THS to still be used and unfortunately for whatever reason a significant nose down input is not made. Perhaps Airbus should freeze the THS after an ADR failure and not wait until an abnormal attitude is reached leaving you with an A/C that is possibly trimmed just outside the range of a UA. 1. What do you mean by "freeze the THS": cancel or pre-empt all commands to move it, up or down, unless the pilot manipulates the trim wheel? :confused: |
Stop auto trimming with an ADR problem, which would have left the trim at 3 degrees which was speed stable for FL350. Once the problem was resolved allow the auto trim to resume.
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.......Look, if you haven't read much of the thread.......... |
At this point, 67 pages in, the thread is random noise.
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I agree stepwilk, too little known information was put out and who knows when any more will be known. Now all that is being discussed is the sliver of information they released. They have it all even though they haven't gone over it thoroughly but the CVR would tell a lot of the story. We can go on about why the PF elected to pull up and start the whole disaster but the CVR will explain why he thought he had to do it. They already have that information. Eventually we will know too. Guess we will have to wait. It sucks, doesn't it?
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FL380
As a side matter to that of course deviation, on the night in question, wouldn't FL 380 have been reserved for South bound traffic?
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Does the A330 have inertial VSI?
It's not normally in my scan, but may have given them an indication that they were in a deep stall? |
Can anyone post the images of the given thread... :sad:
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stepwilk, bubbers44,
are you suggesting people shouldn't have the right to express whatever they think, or that none is valid? No more information would reveal whatever we don't yet know, BEA released information along that line or it would be meaningless and misleading. You don't need to know the color of cockpit inetrior if you know that the captain went to rest minutes before entering a CB other flights bypassed, that the PF held pro-stall controls throught the fall, and that it resulted as it did. The answer as to why to me is also pretty obvious, it's in the previous sentence. I wouldn't discount opinions of worthy others, just because so much was written, you don't have to read it all. |
best analysis so far imho.
TheShadow in post 1222 gives the best analysis so far on the facts that are known to us. I advise everyone who has an honest and keen interest in this accident to keep a a good look out for his postings.
I go back to gardening, the fate of a retired pilot. |
BREATH, it helps. Getting old sucks.
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Lonewolf_50
I noted that the Flightglobal article referenced in #1242 stating Abnormal Law was not entered was dated in January of this year, prior to recovery of the data recorder. I would guess it must be re-evaluated in light of the flight data now available. In Abnormal law I've read that only the manual trim wheel would alter the angle of the THS. I've also read that at 13 degrees nose up THS, the sidestick would not have authority to lower the nose. So this is a big and unresolved issue. |
are you suggesting people shouldn't have the right to express whatever they think, or that none is valid? Hence random noise. My rule of thumb is that when a thread begins to top five pages, it's time to move on. Everything important to say has been said. |
I noted that the Flightglobal article referenced in #1242 stating Abnormal Law was not entered was dated in January of this year |
Good Memories
I go back to gardening, the fate of a retired pilot. |
stepwilk
"Hence random noise. My rule of thumb is that when a thread begins to top five pages, it's time to move on. Everything important to say has been said." So practice what you preach and move on, stepwik |
Indeed The Shadow a great post. Thank you.
However let's cut to the chase. Has anyone flown the AF scenario in the simulator and successfully brought the A330 out of its super stall? It is either possible or it isn't. Now with the enlightenment that it is not just T tailed jets that can end up in this predicament, then some of the protections that are fitted to rear engined aircraft must be considered for other types. High speed, high altitude stall recovery must be trained for or preferably, a better awareness of what is causing an erroneous speed indication. If Air France knew there were issues with the Thales pitot tubes, it was allegedly grossly negligent that they did not either train for the situation the crew of AF 447 found themselves in, or accelerated the replacement of the defective parts. Perhaps it is time to look at a safer design from the past. The VC10 is the only T-tailed airliner never to have been involved in a deep stall situation. The "10" had a very large and powerful tailplane which was mounted high and swept back. If a stall did occur the elevators were situated well aft from the wing blanking effect. The AF A-330 was lost from an altitude of 38,000 feet, but the VC10's were frequently flown at 43,000 feet with a little help from the droops. Other designs such as the Trident and 1-11 proved in testing to be irrecoverable in a deep stall without a tail chute. I find it hard to believe that with all of its automated protective systems, this A330 was lost from such a high altitude in an apparently unrecoverable stall. Perhaps Boeing have got it right? |
Hi,
However let's cut to the chase. Has anyone flown the AF scenario in the simulator and successfully brought the A330 out of its super stall? It is either possible or it isn't. On the other hand I suspect (after all the allegations in the press or experts about possible prob with Airbus procedures .. etc ..) that Airbus will make a real demonstration flight and introduce a loss of pitot ... and demonstrate that it was no problems for continue safely the flight. They will save their ass |
I find it hard to believe that with all of its automated protective systems, this A330 was lost from such a high altitude in an apparently unrecoverable stall. Perhaps Boeing have got it right? - To conclude it was unrecoverable we would need to know that there were efforts made suitable to recover it. We know of one ND input very late in the game the a/c seemed to be responsive to, but not how long it was sustained. In fact we have no information whatsoever about what happened the following 1m30s - I can guarantee you it's possible to stall a Boeing. And by pulling up you're not likely to recover that one either |
Test pilot "Cats Eyes" Cunningham put a Trident into a deep stall and recovered.
I expect nothing less of AIRBUS and its A-330 test pilots. The AF 447 crash has shown that in the certification process, there is a gaping hole. |
"Hence random noise. My rule of thumb is that when a thread begins to top five pages, it's time to move on. Everything important to say has been said." So practice what you preach and move on, stepwik Quite a few of us are waiting for some new facts rather than a rehash of what might have happened. |
A/S / Alt
After the pitot was blocked with ice it performed as an altimeter. It would direct the pilot in a counter intuitive and divergent fashion, stick back resulting in increasing indicated airspeed. Stick forward would indicate a speed decrease, so much so that the AOA was disabled.
This is the saddest story since Aero Peru. |
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