Hi Dozy,
Maybe that this info is taken directly from its control surface feedback related to CG and trim position, rather than airspeed? (in Airbus, autotrim works without airspeed and it is based on FCMC/IR imputs)

Could well be, takata - but the point is we don't know, I'd suspect most B777 pilots don't know *exactly*, and the question is - would you bet your life?

Hi DozyWannabe,

That's strange - because yesterday it definitely felt like I have to exert more force the more I move it.

I don't know, but if it defaulted to sensed zero air speed, then it would simply feel more twitchy. I would still be able to cope, just that I'd need to exert say half the force for the same effect.

Do you bother to read any of my posts? That is exactly what a pilot wants to do. He wants manual control of his own pitch trim during UAS. Any fuel transfer cofg problem could be halted by turning off a couple of pumps until later.

I'm pretty sure that's the same thing I'm saying, is it not?

I'd say that reads more like what *you* want to happen. I'm sure you wouldn't claim to speak for all pilots any more than I could claim to speak for all engineers. Some pilots want different things is all - it'd be a boring world if we all wanted the same things given the options we have nowadays, wouldn't it?

This is not really the question about making any bet.

I think that the constant comparison between A & B is fairly displaced and most pilots here have moved on on this subject. The fact is that it seems that there is some obvious differences when driving such aircraft, controls, autotrim and CG computing, being of course part of the equation.

Now, it isn't anymore about judgement but understanding. Airbus concept is not that bad but may certainly be improved: there is still quite a wide margin before considering it "near" perfect, whatever Boeing is doing on its own side.

Actually, some point of view developed here about Airbus a/c is based on a "conventional aircraft" with fanzy added systems, and some people are trying to figure out how much it is useful or could be useless/dangerous in certain cases. While in fact, the starting point for this design was not a "conventional" but a "protected aircraft" which may eventually lose some of its systems until the point that it will look very much like such a "conventional aircraft".

Then, it is in fact possible that in the middle of this reversion, you'll be left with an "hybrid" aircraft which is not what any kind of pilot (Airbus or others) is very likely used to. While an Airbus pilot, used to those systems, would preferably keep whatever is still working rather than to reverse to a fully "conventional a/c", another pilot would prefer to get it directly "conventional" because it is also what he is much more used to.

Nonetheless, one of the issue that I'm starting to understand, is that Airbus "protected" systems are now in use for about 25 years. Basically, all the documentation was at first aimed at those pilots converting to their systems from "conventional" a/c. Now, they also don't explain how it feels like to fly such "conventional a/c", but rather the opposite. In turn, there is not that much emphasis about how to do in "conventional" configuration, which was certainly ok at the time, because everybody knew to fly it like that.

Is it still the case today?
If you look at those two young F/O (less than 40), they obviously never flew anything else than Airbus (A320 and A330/40) after their basic training. Hence, what would be the point to say in FCOM: if you are in direct law, you are now flying a "conventional aircraft"... when they may have no idea about what it is really like?
Some questions I'm asking myself at this point.

Picky Perkins, a few thoughts from one of your posts.
.
FWIW: one of our posters (Mikelour) taught in the A330 sim. He has told us that there were/are some Unusual Attitude training scenarios where use of trim wheel was included. Is not Unusual Attitude related to Upset? :confused:
Possible cultural factor. Whose gonna own up to that one? (Do I hear crickets chirping?)
This point appears worth repeating.

An AoA gauge might have been useful secondary scan instrument ... *ducks*

EDIT: I'd like to address a point in terminology.

Typically, an aircraft has primary flight controls and secondary flight controls. Aileron, rudder, or elevator, (primary) often have a trim surface (secondary) that allows you to influence the primary.
(Other secondary are: flaps, slats, spoilers, speed brakes ... which change air flow over a wing). (Thought: aren't spoilers sometimes in the role of primary flight control at high speeds and high altitudes?)

The relationship between the THS and the Elevator on this aircraft looks similar to how a trim surface on a conventional elevator (with fixed Horizontal Stab) influences elevator position.

THS is thus a primary flight control. Or is it? Initial control deflection of the stick moves the elevators (so the elevators are a primary flight control).

Does this make THS a secondary flight control?

Well, if one is controlling the nose with the trim wheel, THS becomes the primary flight control surface.

I may be trapping myself in archaic terminology here.

Can someone help me see this more clearly?

Hi,

Woooaaa
The next question is...
Why Airbus bother to make available a "direct law" if the "new pilots generation" are not able to pilot the plane in that law ?
Is "direct law" can be crudely translated as "direct crash" ?

@Dozy:
 

UAS other than A. FBW airliner:

Unreliable Airspeed Indications.
Unreliable airspeed indications can result from blocking or
freezing of the pitot/static system or a severely damaged or missing
radome.
When the ram air inlet to the pitot head is blocked, pressure in the probe
is released through the drain holes and the airspeed slowly drops to zero.
If the ram air inlet and the probe drain holes are both blocked, pressure
trapped within the system reacts unpredictably.
The pressure may increase through expansion, decrease through
contraction, or remain constant.
In all cases, the airspeed indications would be abnormal.
This could mean increasing indicated airspeed in climb, decreasing
indicated airspeed in descent, or unpredictable indicated airspeed in
cruise.
Unreliable airspeed may cause noticeable effects in the normal speed
stability of the airplane since the normal pitch control law uses indicated
airspeed.
If the indicated airspeed falls below 50 knots, the flight control system
changes to the secondary mode, which does not depend on airspeed.
The autothrottle system also uses indicated airspeed and should be turned off.
If the flight crew is aware of the problem, flight without the benefit of
valid airspeed information can be safely conducted and should present
little difficulty.
Early recognition of erroneous airspeed indications requires familiarity with
the interrelationship of attitude, thrust setting, and airspeed.
A delay in recognition could result in loss of airplane control.
The flight crew should be familiar with the approximate pitch attitude for
each flight maneuver.
For example, climb performance is based on maintaining a particular
airspeed or Mach number.
This results in a specific body attitude that varies little with gross weight and altitude.
Any significant change from the body attitude required to maintain a
desired airspeed should alert the flight crew to a potential problem.
When the abnormal airspeed is recognized, immediately return the airplane
to the target attitude and thrust setting for the flight regime.
If continued flight without valid airspeed indications is necessary,
consult the Flight With Unreliable Airspeed/Turbulent Air Penetration table
in the Performance Inflight section of the QRH for the correct attitude,
thrust settings, and V/S for actual airplane gross weight and altitude.
Ground speed information is available from the FMC and on the instrument
displays.
These indications can be used as a crosscheck.
Many air traffic control radars can also measure ground speed.

Secondary and Direct Mode Pitch Control

Airplane pitch control is different in the secondary and direct flight control
modes.
The control columns now command a proportional elevator deflection
instead of a maneuver command.
Secondary and direct modes do not provide automatic pitch compensation for:

• thrust changes
• gear configuration changes
• turbulence
• flap and speedbrake
configuration changes

• turns to 30° bank angle.

In secondary and direct modes, the elevator variable feel system provides
two feel force levels instead of a continuous variation with airspeed.
The force levels change with flap position.
With the flaps up, the feel forces provide maneuver force levels that
discourage overcontrol in the pitch axis at high speeds.
With flaps extended (flaps 1 or greater), the feel forces decrease to
provide force levels appropriate for approach and landing.
In the secondary and direct modes, both the primary pitch trim switches
and the alternate pitch trim levers move the stabilizer directly.
There is no trim reference speed.

Your post is food for thought! Cautions about attitude, (assiete), continued flight w/UAS, etc, very compelling.

Could you comment on the inclusion of "damaged or missing" radome?

Long ago, it seemed to me at least possible that the radome could have been damaged by hail, or lost due overspeed. This could tie in with the suspicious lapses in Radar (Wx) uses and deviation questions. Likewise, a damage to one or more Pitots if impacted by debris?

bear, upon what data are you basing your idea of overspeed loss => lost radome? At the speeds flown, lost radome likely causes non-trivial drag, likely a radar fault, and hence an ACARS message well before the upset event.

I don't see there being any data presented to date that supports this hypothesis. Indeed, what little we have from CVR is that pilots had noticed something ahead and made a small course change based on that info. So, if radar was not working, that would most likely have come up in conversation.

My point was to underline what seems (for me) to be lacking in pilot's basic documentation about flying their aircraft. I don't think that such knowledge of "conventional aircraft" may still be considered today as being part of the background of that many pilots than it was in the past. Much more informations would be needed in this flight manual about how the aircraft would behave in manual control during reversion phases mostly without any protection.

If your point was to make fun of mine, this is completely zero added value, like one said. Obviously, any pilot needs surely to be trained from A to Z in order to ensure his full ability to fly whatever aircraft. Hence, I think that this manual is not reflecting very well this basic requirement, considering some parts of its flight domain, for the reasons explained above.

Hi takata,

There is a beautiful aircraft waiting to come out once the Normal & Alt Laws have been removed.

From FCTM
Direct Law
In most triple failure cases, direct law triggers.
When this occurs:
• Elevator deflection is proportional to stick deflection. Maximum deflection depends on the configuration and on the CG
• Aileron and spoiler deflections are proportional to stick deflection, but vary with the aircraft configuration
• Pitch trim is commanded manually
Handling characteristics are natural, of high-quality aircraft, almost independent of the configuration and of the CG. Therefore, the aircraft obviously has no protections, no automatic pitch trim, but overspeed or stall warnings.

OPERATIONAL RECOMMENDATION:
The PF must avoid performing large thrust changes, or sudden speedbrake movements, particularly if the center of gravity is aft. If the speedbrakes are out, and the aircraft has been re-trimmed, the PF must gently retract the speedbrakes, to give time to retrim, and thereby avoid a large, nose-down trim change.

lonewolf

I think my approach is one that is misunderstood by some. I haven't proposed any kind of conclusions, I am making an effort to keep my mind open to possibilities that indeed may have naught to do with 447. In an effort to understand UAS, overspeed, RadarWx, etc. I am adding to my own personal backgound, and if at a later time, a conclusive presentation is made (it will be, we hope!), then a broader understanding offers a firmer foundation for finality.

Within days of this accident, I was focused on the attitude of the a/c at a/p loss, until it became increasingly ignored in favor of what I thought was extraneous interest by the thread in general. What goes around comes around, and here we are with A33Zab's post of "Other than fbw UAS procedure."

We are back at the several seconds around the loss of the autopilot.

I believe what is technically considered "Upset" (not at all what many think it is....) happened seconds (or more) prior to a/p dropout. The LOC, (again by definition) 'happened' at "I have the controls".........

I do not need to be correct. I have no airframe bias. I am a pilot. I am with the crew, until such time as anyone can conclusively prove to me that PE was the procuring cause of this tragic accident.

Was it "in there"? Who among the pilot community would have an expectation of flawless competency in such conditions?

I have no "need" to be understood. On the contrary, I crave to understand.........

I think that any pilot who is flying it will tell you that it is certainly also a beautifull aircraft to fly in Normal law, which is what they are doing 99.99% of the time. The problem that need to be addressed, I think, lies somewhere else:
When there is such a non-commanded law reversal, it is either in the sim (where, most of the time, always the same scenarios are played), either in very critical conditions. It will be then, for anyone, quite hard to appreciate how much "beautifully" it is flying without either airspeed, inertial reference, hydraulics, electrics...

rudderrat

well said. Do you have any thoughts on the speedbrakes v. Trim and "nose down" trim change? Also, could one of the right side spoilers have failed to stow completely, causing that annoying (and persistent) "roll" to starboard? If so, would the rolling aspect of the climb and descent be possibly related?

I know that you are SO very "open-minded". But have you got ANY information that she could have been in direct law, at any point before crashing, not even mentioning before this UAS declared?
Bearfoil, nothing unusual happened before 0210:05, take it as a fact or consider, with your usual very open-mind, that the BEA is lying the entire world.

I do NOT believe BEA are lying. I do NOT have sufficient evidence to pour concrete around my opinions, as some have. I do have an open mind. I will embrace the truth when (!) it appears.

You are the one who knows, evidently, sufficient data to reject all speculation that isn't conformed.

For what it is worth, You have opened up greatly in the last two weeks, and offered valuable information in every way, some even that is neutral re: Airbus.

I try to eliminate the personal from this thread. If you are correct, and my prose is mostly zero-value-added, you should try ignoring it, or resisting the urge to respond to it with snark. If it is just so much dead weight, you might want to avoid worrying about someone else's bandwidth?

Fair enough.
My urge comes from your own typical urge at bouncing up after any word taken out of its context.
Did you even noticed that Rudderrudderrat was quoting something related to Direct law, or not? Hence, the first question to address, with an open mind, should have been: was she in this mode? If one bother to answer it, his fast composed theory would spin and crash many times faster than AF447.
Nothing personnal otherwise.

In your opinion. I personally don't understand this conservative streak in a minority of pilots. Why so negative about something which was designed to help you do your jobs and move the art of aviation forward? Why such a burning need to move no further forward than the 1970s?

(Just to add, I'm not being facetious here - heaven knows I'd rather be hacking away at low level code on the machines I grew up on on a day to day basis than doing the corporate stuff that puts a roof over my head, and I know what it is to feel that one's career path has been commoditised by the endless march of big business - but IMO it's not fair to blame the technology for that)

mais oui.

My Bad. Lately I type faster than I think, I am sorry. But is there any value in considering that the trimming the A/P was doing had some importance on the PF's choice to manuever quickly instead of "waiting"?

Do you have a thought re: the first manuever? It happened, it had a reason, and no, no one can read the PF's mind. Qu' est-ce que c'est?

thanks

Because it MAY have been a contribution for this accident and other incidents?

Hi DW,
You misunderstand me.
Normal Law is brilliant, the aircraft is wrapped in cotton wool.
Direct Law is beautiful "Handling characteristics are natural, of high-quality aircraft, almost independent of the configuration and of the CG."
Alternate Law is a confusing mixture of both - without "protections" and without the natural longitudinal speed stability the aircraft has naturally.

In the 70s, when I flew L1011s we had CATIII NO DH auto land capability, Autopilot CWS (like hand flying in Normal Law), autothrust Alpha Floor protection (Like VLS).
When the auto pilot was out, she handled beautifully with manual pitch trim.

What forward progress do you think we've made?

@RRR:
 

Nothing against L-1011, way ahead of it's time but:

Incidents and accidents

As of August 2008, the L-1011 was involved in 56 incidents, including 11 hull-loss accidents (out of 250) with 534 fatalities.

As of June 2011, the Airbus A330/A340 had been involved in thirteen major incidents, including six confirmed hull loss accidents (out of 1140) and two hijackings, for a total of 338 fatalities.

Not to mention that the thing's lighter, requires one less donk and one less full-time crew member (which makes it more economical to run). Don't get me wrong, the L-1011 was a fantastic airliner and still has to be matched in some aspects today, but in economic terms it was flawed and sales suffered badly at the hands of the DC-10, which turned out to be another more seriously-flawed gem.

A33ZAB
 

Thanks for a very easy explanation of all the laws. :ok:

Hi,

In my opinion it is the heart of the problem
A plane (was) should be a means of transport which allows to go quickly from one point to another and is relatively expensive for passengers and must be of an acceptable return for its owners (airlines)
A plane must now be a means of transport which allows to go from one point to another (but now the emphasis is no more on speed ! ) and to be inexpensive for passengers and who must have a return to report the maximum possible for its owners (now mainly banks and shareholders)
This is also the other side of progress
Progress is being made in terms of economy and efficiency ..

Hi A33Zab & DozyWannabe,

It depends how you manipulate statistical data. You have to compare apples with apples.

The link below lists fatal events with aircraft type where “A fatal event is defined as 'an event in which one passenger was fatally injured solely due to the operation of an aircraft.' The number of fatalities in each fatal accident is irrelevant in the statistics presented below.”
AirDisaster.Com: Statistics

According to this analysis, B727, B737, B757, and B767 are all ranked as having fewer fatal events per flight than 320 series.

The L1011 is ranked as having fewer fatal events per flight than DC-10, DC-11 or B747.

The problem with the AirDisaster stats is that Chris Kilroy is a known Boeing partisan, and revealed some very negative opinions of Europeans and the French in particular in 2001.

Besides that, those figures don't take into account the longevity of each airframe, and the fact that a lot of accidents in new types will occur in the first 5 years of service. Once an aircraft has plugged the line for a while, its "quirks" are known by the piloting communities and they cease to be as much of an issue. It would only be fair to either compare the first decade of service of each, or discount the first 5 years as a statistical anomaly and take the stats from there. Either way it skews the stats in favour of aircraft that have been around for longer.

Hi DozyWannabe,

Page 20 on this Boeing Document is up to 2010. (I can't find an Airbus Document yet)

http://www.boeing.com/news/techissues/pdf/statsum.pdf

Once I've analysed the data a bit more - I'll be able to reply better.

Edit. From Page 20:

Hull loss rate per million departures
rate = with fatalities accident rate / Hull loss accident rate total
B737-600/-700/-800/-900 rate = 0.18/0.30
A320/321/319/318 rate = 0.20/0.33
B737-300/-400/-500 rate = 0.28/0.52

B757 rate = 0.24/0.24
B767 rate = 0.13/0.38
B777 rate = 0/0.18
A330 rate = 0.46/0.46

A340 rate = 0/0.87
B747-400 rate = 0.31/0.62

I can't detect that much difference between B or AB - they are very similar.

If someone tries to tell me that the 727 has a better accident statistic than a modern Airliner, that is exactly the second where I throw the paper away instantly.

FWIW the 747 has a much much worse statistic than the 320 or 737 (especially if you include the older versions).
What do you make of that ???

edit:
Agreed. However the data is only really meaningfull for the 737 and A320 from a statistical perspective.

With the A330/340 and 777 the absolute number of occurences and flight cycles (Not flight hours in this statistic) is too small so that one occurence more or less makes a difference between excellent and not so good. Best example is Concorde from 'safest' to 'unsafest' airliner after one single crash.
When you have got >20-30 Hull losses the statistic starts to become more meaningful.

Law + ths
 

Could some expert explain the following part of the
FCOM page

FlightControls Normal Law, 1.27.20 P2 Seq. 001 Rev03

Pitch Control / light mode

Would that not inhibit the trim to move ND when unloading enough (provided elevator authority is big enough)?

further down:

Shouldn´t that have prevented or hindered the THS to move to 13°ANU?

Im familiar, that the described paragraphs relates to normal law. Are those vital features lost in ALT LAW?


A few pages down another one causing headache:
Flight controls Reconfiguration Control LAWS
Alternate LAw Alt 1
Protections
Low speed stability

As IAS was incorrect from beginning and leading to AP /Athr disconnect, and later dropped to 60 kts, could this mode have been activated on behalf of the wrong IAS? How would the ND input by the system differ on behalf of an incorrect IAS (systems gets slow IAS, but actual AS is considerable amount higher, would the ND input be more pronounced then with real lower IAS?
Could this have tricked the PF to counter the system ND input (if this protection was active and the ND input was commanded by the system) by NU SS input and contributed to the high pitch result, when PF NU input overrode the ND input of the Low speed stability protection? Which was then possible, because pitch attitude protection is lost in ALt law?

And what is meant by the term "bank angle compensation is provided"?

I still dont get the whole picture of those law changes and the asociated protection changes or protections lost.

So please be patient, if my questions look uneducated or if the questions have been answered already. And it has nothing to do with A vs. B.

@RRR:
 

Conclusion: FBW is as worse as NON-FBW?

I can detect a difference, why did they separate A330 with A340?
They are identical A/C apart from amount of engines.

... shows statistics valid through December 31, 2004.

JC, shareholders are, by definition, owners. Now that we established this, shareholders might be banks, yourself, or your retirement plan. Whatever the case, Airlines are historically a risky investment most of the time.

Could you comment on the inclusion of "damaged or missing" radome?

I don't think I saw any comment on this question.

Pitot static performance is dual input - pitot and static.

Apart from blockage pitot performance generally is pretty robust and doesn't give too much in the way of problems.

Static performance, on the other hand, is a bit of a prima donna.

- in the certification phase development of PEC data is a major part of the flight testing program.

- we even go to the trouble of using trailing drogue (cone) static sources to get out of the aircraft's interfering flow fields

- modifications forward of the static source can be a nightmare for PEC effects. I recall one tale about a B52 program where a mod up forward made a BIG difference to IAS during the takeoff - fortunately, the TP had a feeling in the water during the first takeoff and rejected.

- in routine operations, the easiest way to get a massive airflow disturbance which will always cause an effect on the PEC is to have the radome disintegrate ...

For those who like some arithmetic and lots of fancy mathematical symbols, you might like to read reports like this one. (Everything you wanted to know about pitot statics but were afraid to ask ...)

WileyB

Eddie Richenbacher stressed "Reliability" of air transport back in the 1930s. His backers understood that this had to include the then new technologies, Radio Range etc. Others understood that any mishap, and that included off- schedule operation, costs money and ultimately insurance premiums would rise.
"Safety is no Accident"
Newer aircraft became larger, faster, and more productive, and must be kept working to repay their initial cost. And they became more efficient. Staff need suitable training, to get the best from the Capital - it is an investment. Reliability encourages profitability.
( Just think of re-equipping AF with Constellations to do its present work. In 1970 I replaced the fleets of one airline with 400 Yorks, which would not have been subject to Night Jet bans ! )

ISIS is not especially larger than the standard standby indicator, and the standard standby indicator is not more 'unreadable' than the ISIS.

Pretty rare, but I can still remember flying under MEL an entire week or so without it due to a defective trim tank isolation valve.

Never the MAC could have been to 38% after only 3 hours something in the flight, not with the initial very much forward 23% CG at takeoff time. My own estimate would have put it around 32% at the time of the event, but the BEA now mentions 29% ...

If now to have to trim an airplane overloads a pilot, so, something is very wrong with the airbus philosophy. How will cope a pilot the day he has to do it when the system pushes him to lose that practice. Let the pilot trim, it is just more pleasure and SA in the mean time.

Icing maybe or just the unusual 'AoA' for those static probes induced unreliable readings for altitude and/or Vertical Speed ...

Something big is missing in the story : I can't believe 3 guys would have maintained NU inputs for 3 minutes with 3 A/H showing blue blue blue and 3 altimeters going down like crazy. BTW, what did say the captain ? Nothing ... ?

BEA, just publish the data, and if we don't deserve them, the victim's families surely do. Why can't they get them ... ?

CG
 

How come BEA didn't know the takeoff cg was 23% at time of first report? Why didn't they do your math?

As long as BEA is being vague and inspiring wild guesses: what is the chance that the takeoff cg was really 30%, and not 23%? You can see where that would lead..

Is cg calculated based only on pre-takeoff W&B, or is it computed constantly from AOA, IAS, ALT and trim?

for me cg seems calculated based only on pre-takeoff W&B.... and fuel consumption....

who made the load- and fuel-weight datainput normaly?
there can also be a data entery error, captain again needs best skills to control this



@ john tullamarine can you explain the different places of the pitots between A+B, can this have an influence of the reliability (ice)

@ CONF:
 

Happen to have deactivated a THS tank a few months ago, due to access panel leakage.
Repair interval Cat C (10 days), empty TT; manual closing and deactivating TT isolation & TT inlet valve to prevent fuel entering TT but to keep trim pipe with fuel for APU ops.
Crew selects TT Tank Feed switch to ISOL, 1% fuel to be increased due CG control not available.
Indeed very rare, it was the first time in our company.

@GB:

Flight preparation:

The flight crew should insert the weights after completing all other insertions. This is to avoid cycles
of prediction computations at each change in flight plan, constraints, etc...
If ZFCG and ZFW are not available, it is acceptable to enter the expected values in order to obtain
predictions. Similarly, the flight crew may enter the expected fuel on board, if refueling has not been completed at that time.
If ZFCG, ZFW, and BLOCK FUEL are inserted, the FM will provide all predictions, as well as the EXTRA fuel, if any.

In Flight: