Lemurian posted
If you look at the CAS trace the CAS does not exceed the stall warning value until 15:45:16, at which time the a/c has a positive pitch rate which would increase Vs - the stall warning stopped 3 seconds later after a period of more constant pitch. Seems OK to me. It seems to go wrong from 15:45:21 with that relaxation of forward stick, as NoD has pointed out.

NoD point taken re the stall recovery.
A little anology.
2 drivers, one in a manual transmission (stick-shift for our transatlantic readers ) the other an early generation Auto (i.e not DSG/Tiptronic )
During an overtaking manouvere a car pulls out unexpectedly from a hidden entrance.
The driver of the manual car, if he needs more acceleration than is available ,"should " instinctively shift down a gear, as he is accustomed to that action. He may of course fluff the shift, but if he is a decent driver the action should be fairly instinctive.
The driver of the Auto has a much simpler task, he just mashes the pedal to the floor & the box "kicks-down"

However, imagine due to some glitch it doesn't. . . how quickly is that driver going to reach for the lever and negotiate perhaps a detent & select a lower gear ? I would suggest not too quickly, because it is not an instinctive action.

I think the same scenario has perhaps taken place here. The crew are not accustomed ,in manual flying , to using stab trim, so when they really really needed it, it wasn't an immediate instinctive reaction to use it.

Yes, I do drive a manual car, but yes I admire the latest generation of "driver
controlled" but robotised DSG boxes.
It is merely my opion, which of course anyone is at liberty to disagree with or question, but I think that Airbus took "the driver" too far out of the loop. I don't know enough of 777 (& assumedly- if it ever arrives -787 ) control logic, but the little I know suggests that Boeing is more DSG whereas Airbus is the good ol slushtronic, quietly changing gear, smooth, imperturbable, but try asking the driver what gear he is in at any particular moment & see what the answer is.
Of course the BIG lesson here, is in exactly the same way as the Easy & THY incidents, you have to know what you must do to control the aircraft when normal control actions are not enough & you have to be aware what the machine is (or isn't) doing on your behalf. Different philosophies, similar but subtly different traps.

And for BOAC, the PFD speed scale
The lowest speed value displayed on the PFD scale is 40 kt. and the scale stops at 30 kt. I seem to recall that pre-flight the "actual speed" index sits just below 30 kt. (See it every time I step in the sim but can't picture it!).

Question.... perhaps for MFS ?
If the FDR records the CAS parameter as invalid, is this because
a) it is not worth recording at below 40 kt, perhaps due to likely fluctuations etc., or
b) does it imply that the CAS output from the ADR is invalid? Which is a whole new ball game involving red SPD flags in place of the normal speed scale.
Note: this is probably a red herring!

captplaystation
I have been driving a DSG for ten days and it's a lot more sophisticated than the Boeings I flew!
Seriously, I take your point about manual flying skills. After 35 years of cables and pullies, I flew the A320 for 15 months. Then went back on the 747 Classic - the first ten minutes of hand-flying were very ugly indeed, thank heavens for simulators. I had to relearn the instinctive hand and trim movements needed with thrust changes (as well as a new instrument scan).
When exploring direct law (usually sim detail 4) trainees on A320 type ratings benefit from plenty of reminders about trim - even the ex-737 ones.

TP

I guess when you get to 93 years old :hmm: :D you need a little help with the gear changing. Nice to retain the option though to "do it yourself" & faster/cleaner than you would ever manage unaided.

NigelOnDraft
Sorry, I didn't make myself clear. I'm talking about the first post-stall situation.
As far as we can extrapolate from the graphs, after the stall warning onset, there is a general trend for the pitch to decrease, hence my assumption that there was no load factor involved there...At time :19, the speed is well above 120 kt and I don't expect the warning to have lasted that long.
Of course, TyroPicard's remark :
is as valid as mine.
I don't pretend that I'm right, I'm just trying to picture the events as they would have appeared on their instruments and the general cockpit atmosphere.

NigelOnDraft
Yes, the first really puzzling aspect of this accident... Loss of SA ?
But immediately, the next question would be "Why the loss of SA ?"

PS : I've just discovered Sindhu's post and whether the expert sent by ALPA will help or not remains to be determined. There is though a damning sentence in that press release which was initially used to protect the crew :
improvise ?

These guys were coming from different places... they may even have had different agendas... they certainly didn't know one another well... they also weren't particularly well-practised at doing what they were attempting to do.

OK, maybe one of them was (well practised) and gave the lead, having much more confidence but leading them into the devils den without any armour or weapons.

HarryMann
 

You could just as well be talking about the Toulouse A330 accident.

Since when Airbus has tightened its own test procedures a lot, of course.

What is suspect is that the BEA did not publish the data for that third AOA sensor ...

THINK IT'S TIME AIRBUS/BOEING INSTALLED A BIG FU**OFF BUTTON ON THE OVERHEAD PANEL...

PUSH FOR AEROPLANE...........PUSH FOR COMPUTER.........

while i cautiously agree automation is the way forward there have been too many incidents/accidents with the modern logic's of so-called aircraft protection either by bad design or pilot misunderstanding/training.

direct law,alt law,normal law
there should be only one blo*DY law

PILOT's LAW.........


I humbly fly a 172 when i turn the yoke right woopee.. the aircraft banks right,i press the brake the aircraft stops,whats so different with modern jets ?

we have overcome a wave of accidents in the 60s,70s and 80s caused by weather,pilot error,failover and atc errors only to enter the new milenium with a host of altogether new problems, self created seemingly...the more systems they develop to help pilots they just seem to move a step further to removing more control from a pilot.

Recent AMS 737 springs to mind,pilots have forgotten how to fly the damm plane because they have sooooo much other crap to contend with..can i do this ? ...what will happen if i do that...can this be done in this or that mode......
(anyone remember the Romanian pilot dueling with a 320 midair trying to regain control way back...)

Flying an aircraft should be instinctive regardless of size or complexity would be interesting to see how many pilots of modern advanced jets would fare plopped back into the cockpit of an ole 172 in IMC ..point being the pilot should AWAYS..ALWAYS BE AHEAD OF THE AIRCRAFT AT ALL TIMES.
like i said i'm all for modern technology but tecnology designed BY PILOTS FOR PILOTS not by some computer geek in the comfort of an office, in my opinion a lot of these systems should never have been certified if even a remote chance of failure or misdiagnosis can occur which has surely been an indirect if not direct cause of many accidents.This concerns me as a passenger and a pilot.

Also until the CVR transcript is released we dont know !!!!! would'nt be the first time we were fed BS in a report........

You seem to show a remarkable lack of understanding of techonology.
I can see why you want such a button, but have you really considered the consequences of switching off the computers?

How do you think speed and altitude are calculated? The give away phrase there is calculated, not measured. Yes, by a computer.

Unless you have a mechanical linkage all the way from the lever to the fuel valve, you have a computer in there somewhere.

Unless you have a mechanical linkage all the way from you feet to the rudder, there's a computer in there somewhere.

There must be many many discrete computing elements in modern jets - just which ones would you like the big button to switch off?

Even if you come up wit a list, how do you ensure the list is correct for every conceivable possibility?

paweas

I think you have missed the whole detail of this accident :ugh: The point was as it all went wrong, it was under "Pilot's Law"... but you cannot legislate for crews electing to fly the aircraft at Min/Stall Warn speed -15K @3000', not completing a stall recovery etc. etc. and then applying Full Rudder at/in the stall.

No - please enlighten us :ooh:

NoD

paweas,
the two Romanian incidents (in fact 1 incident & 1 accident ) were both pre FBW A310.
Nonetheless lack of pilot comprehension of what the machine was doing figured heavily.
In the Orly incident the aircraft was auto trimming & the pilot was applying elevator in opposition causing the aircraft to trim even more. This resulted in attitudes very similar to the XL accident & an accident was avoided by the smallest margin.
The accident occured at Bucharest on departure when the A/T only retarded one throttle when climb thrust was demanded .The A/T advanced thrust on one engine & continued to throttle back the other & the aircraft ended up rolling over on it's back & crashing with the A/P allowed to invert the aircraft into the ground whilst the crew sat there & watched it. It was believed that the Capt may have been incapacitated at the time.
If not, that is indeed a generous description.
So, even that level of automation was causing problems, not a surprise that nowadays the levels are not fully understood,even more disturbingly, we don't seem to have learned the lessons from all these years ago. Incidentaly,the circumstances of both of these previous incidents are at least partially reflected in the outcome of XL & THY.

stickyb
 

I think you could have chosen a better example when you posted "Unless you have a mechanical linkage all the way from you feet to the rudder, there's a computer in there somewhere."

Sure, in normal operation the computer is working away in there, but I believe the A320 does have a backup cable system to the rudder.

P.S. I wish these idiot "big red auto-off button" proponents would stop and think. Do they really imagine any manufacturer is going to provide full mechanical backup to something the size of an A380? Apart from the tons of cables, pulleys etc, how many olympic athletes would you need to push/pull on the controls.

paweas,

Well in the case of a FBW A/C , you turn the stick (A) or the yoke (B) and you get the same woopee … limited to a certain amount of bank just in case you’ve over turned the control because your coke just dropped in your pants, and you press the brakes but hey! you’re not missing the assigned exit because you’re happily skidding down the wet runway.

There are obviously more pros than cons regarding automation. IMHO I think the big issue here has two main components:
- lack of understanding of the system behavior in adverse situations.
- Indulgence in risk assessment.

If one does not foresee or expect the unexpected and have a plan for it, you’d better not put yourself through unnecessary risk.

GD&L

GearDown&Locked
And, as most of the pilots have been saying in this thread, it all boils down to training.
IMO, the emphasis has been put on the protections rather than the details of the degradations of the systems :
-From "normal Law" and its subsidiaries / auto trim on the THS
-to "alternate law" / auto trim on the elevator
-to "direct law" - and why the further degradation from "alternate" to "direct pitch" with the landing gear extension .../ manual trim, well announced on the PFD.
Still IMO, the protections are quite easy to understand as they are linked to the regulation-required flight envelope and some extreme attitudes... and if that sort of knowledge is easily mastered, we come to the conclusion that understanding the system philosophy is the premise to knowledge of the system details.
Problem is how do you announce clearly the WYSIWYG ?
At this moment, the degradations show only in the disparition of the info that one gets in "normal law", i.e the bank limits, the speed tape...etc...
Maybe, a clearer message like "ALTERNATE F/C LAW" or "DIRECT F/C LAW" could be more easily understood than "USE MAN PITCH TRIM" or "MAN PITCH TRIM ONLY".
The problem lays on the builders assumption that the failures will occur in the course of the managed routine flight...(and who could blame them as they designed an "airliner" ? )...We have all the time in the world to assess the problem and act accordingly... But things get a lot more complicated in the course of a low altitude emergency and this is where a more assertive annunciation is required.

OK.....you guys are getting me back into this mess.


That's what the Pilot is for!

"My" airplane had all that AND cables to the elevator and ailerons as well!


Who says we have to have such LARGE aircraft?!

That is being dishonnest ...

Transmitting control input by mechanical means, by fluid or by wire is not the problem. Providing raw airspeed, or computed airspeed is not the problem.

The problems arises when a computer has its own way of flying the airplane, disregarding pilot inputs. The problems arises when computed airspeeds are used by computers to "manage" the airplane, their ways ...

And finally, the problems arise when the pilots fly the computer laws instead of flying the airplane law, when pilots are selected and trained to fly computers, not to fly airplanes.

In this accident, as far as we know, after the recovery from the first stall :
- either the trim was stuck at 11° "up" (and the reasons are either mechanical or computer related),
- or the pilots failed to trim forwards in a situation any presolo student pilot would recognize as requiring immediate forward trim.

Any one here made a balked landing go-around at full flaps in a C 172? Or any airplane without auto trim?

Well ... the crew had a lot of time in airbi, and during normal operation, they never - never - had to use the manual trim wheel ... And all of a sudden, that airbus (designed to be flown by a doorman ...) stopped to work as usual ... in a most stressfull situation!

Well, we may think that the crew, having entered an unexpected stall at low altitude - due to computer misbehaviour - was quite stressed ... and that means that they lost a good part of their intellect.

So they kept pushing the stick forwards, expecting to control the pitch attitude "as usual" ... while the computers had changed their minds about auto trim. The aircraft performed a chandelle ... and quite naturally, in such a stressfull situation, the pilots forgot to use that trim wheel ...

So the aircraft entered a ballistic parabolla before going totally out of hands ...

Gives us pilots, intelligent pilots, pilots trained to hand fly an aircraft ...

Just for information
 

The aircraft was a DC-8 performing a flight evaluation test post Dcheck and some system update on Dec 22 1996 :

(source ASN data base : here )

Rings a bell ?
And maybe worth a bit of hard thinking about humility and arrogance.

Not sure if that's directed at my previous post or not, but if it is, I do not see the connection.

The report says the stick shaker was inop yet the sound of it working is on the CVR. But the FE says it's not the stick shaker. ???

Besides, you don't need a stick shaker to tell you when you're nearing a stall and you sure don't need one to recover from a stall. The fact that they did not recover seems to me to be purely a piloting problem in that case, as in some others that have been discussed recently.

DC-ATE How'd you conclude that? The sound of rattling was heard on the CVR. Don't 'things' sometimes 'rattle' when you enter the stall?