I believe 14,000 ft is the highest that any manufacturer flight-tests stall characteristics nowadays.

Couple that with the low-speed limitations of Computational Fluid Dynamics, and we have a whole flight regime for which wide-ranging reliable data doesn't appear to exist.

And plenty of posters on here seem to agree e.g. adding technology to solve every problem?

I would disagree with the underlined statements:
A: I do not believe it "unclear" how to resolve situations, but people have either failed to follow the manual / their training, or they have done something completely unpredictable.
B: It is not essential, IMO, to (completely) "understand" what is going on under the hood. Not even what law the aircraft is in. Yes - a level of knowledge is required, and will help in exceptional circumstances. But if you fly the aircraft sensibly, remember it is still an aircraft and not a computer, and apply basic flying skills, then the finer points of FBW are (as designed) usually invisible to you.

I do agree with the basics of this - initially the benefits of FBW showed up as "protections" prevented some accidents (albeit there was also a learning curve), but there was still basic airmanship and flying skills about.

Now we have a new influx of pilots, who only know FBW, rarely handle the aircraft, the industry relies on the automation. When the automation lets them down, they have nothing to fall back on. Even the older generation pilots have been "deskilled" as well.

GPS on corners
 

Isn't this used on some fighters to sense attitude? Phase lock, phase differences? Maybe on the mil band only?

I would have thought the logic behind stopping the aural stall WARNING when aoa becomes untrustworthy makes sense EXCEPT when an approach to stall has just been sensed. If the warning is blaring away seems more prudent to let it continue. Think the software is missing a IF....THEN branch on this one. Also, if high THS is a very unusual state for normal ops, is there a warning to draw attention to it?

Inquisitor

..out of the profession for many years now but don't necessarily
agree CFD is limited to low speed aerodynamics or altitudes.
no doubt even faster computerd are required and different
mesh/models but think it is a very advanced technology now.

..unless you know different.

HarryMann,

Not sure, as I have no expertise in the field myself. I was referring to what somebody far cleverer than I told me when visiting a wind tunnel test facility. He seemed to be saying that in the low-speed, high-alpha regime particularly, there were simply too many variables to produce a solid deterministic model, as opposed to computers running out of steam.

Apparently they have it pretty much nailed for high-speed stuff, though.

Inquisitor

Sorry I misread...

However I know a bit more about that regime and disagree still :)

separated flow is complex and agree demands lots of computing power

it's a matter of filling in the gaps with real w/t models studies.

I doubt there's a lot not known.

I don't believe these are the issues here:

isn't this about the cockpit, training, operational procedures human
response etc,

It's about a lot of things in my mind HM.

I currently work in the unmanned arena, and am desperately fighting those who think that more computers and more automation is the answer to everything.

My own view is that that we have simply replaced one failure mode with another.

I'd be interested to know what's out there in terms of real-world collected data, particularly wrt high-alt, high-mach, high-alpha, low-IAS scenarios? My current belief is that a wide dataset here is absent, save for that collected from real-world accidents?

TheInquistor;
For those carriers doing FOQA/FDM from engine-start to engine-stop and who retain their deidentified data for some period of time, there is a wealth of information for the period and for the "events" you specify.

Sharing such data is another matter. A number of projects have attempted to do this but so far nothing has emerged as a distributed archive of common types. How data is handled, confidentiality, legal implications and legitimate concerns as to data-use impede data sharing. But it's out there.

Interesting idea.
In fact GPS is amazingly accurate when used differentially to calculate attitude down to sub mm accuracy. The timing pulses in the GPS satellite data packets are used to generate relative attitude information instead of the spacial reference data. This has been demonstrated successfully in many small civilian aviation devices.
The problem here is that the wings have tremendous flex especially at the ends. Even the fuselage has a significant movement at the ends. This would have to be compensated for - maybe with laser level.

What is new here ?

What do you think you would be gaining that you don't already have from the INS's ?

Why is this gps attitude capability seen by some as a new fix ?

The existing 3-axis ring laser gyros already pump out all the spatial data you could ever need, with all rates included.

The point is that when an Airbus goes into alternate law, it has less stall warning and alleviation devices than a 1960s Trident. That is not an advancement in safety.

I expect that when the AB was designed, it was not expected that so many aircraft would degrade from normal law to alternate law. But here we are, yet again. It would seem clear that the degraded systems need a stick-shaker/pusher to back up the aural warnings (or a thrust reducer, to lower the nose).

As to Nigel, who says a pusher or thrust reducer would not be good on take off ( :{ ), this never stopped the Trident having pushers, and not having any problems with them. Besides, AB could easily limit the action to greater than 2,000 ft. And as far as I can see, this would not add weight or cost to a standard AB. I am sure that both stick push and thrust reductions, for approaching the stall in alternate law, could be made as a simple software change.

Absolutely! What accident are you trying to prevent by suggesting sticking GPS's all over the ship? All these accidents had perfectly functional attitude indicators right in front of the noses of the pilots.

It was obvious in the case of AF that neither pilot took any notice of their attitude indicators. Attitude is everything - something that is trained from the first minute of basic IFR training.

If that is being de-trainined in Airbus types then that is the heart of the problem. Forget the more/less automation arguments - if you are hand flying an aircraft, your eyes are on the attitude indicator, with a brief and frequent scan to other instruments such as airspeed and altitude. If you are monitoring an autopilot, not much changes.

In the case of air data problems such as unreliable airspeed including simultaneous stall/overspeed warnings, you are not distracted by the warnings, you simply change your scan from attitude/airspeed/altitude to attitude/thrust until it's sorted.

It just ain't that hard.

Air Asia Indonesia Lost Contact from Surabaya to Singapore
 

Silverstrata,

Exactly HOW does your stick pusher know it is approaching the stall, perhaps it will use the AOA probes. Perhaps it was the ice on the AOA probes that generated the reversionary mode in the first place. Or perhaps it will take it's info from a failed sensor and just push anyway.

That's not actually true in most circumstances. There have been experiments with highly specialised GPS receivers tracking L2 Phase for aircraft attitude purposes that worked well, however general GPS is simply not good enough.

Modern drones have experimented with thermal horizon detectors which work quite well in flat terrain, but have problems in hilly terrain.

The current alternative to INS is a combination of GPS and 3D accelerometers / rotation sensors that provide quite accurate attitude and location information. They do not meet full INS accuracy but at under $100 a sensor unit they are extremely good value.

ASRAAM answers the point I have been trying to make... Alternate Law is, by definition, a Reversionary Mode. It is Reversionary for a good reason, and hence why Stall Protection is degraded.

If the system integrity in Alternate Law was high enough to justify stick pushing, then it would be called Normal Law ;)

Look at the latest OEB - the effects of a "Stick Pusher" in Normal Law :ugh: A320 uncontrollably diving to 4000'/m. If there are hidden flaws in Normal Law, how could you write a Safety Case for such a Pusher in Alternate Law?

What a contrast.

One thread intent on denigrating automation in the cockpit, and another bashing the humans who (possibly) shut down the wrong engine.

In either case a flyable Aircraft has crashed. - I don't know how my computer works, but I can operate it until it goes wrong. Where's the weak link?

<<<I don't know how my computer works, but I can operate it until it goes wrong. Where's the weak link?>>>

I do know how my pencil works and I can balance my checkbook without problem.

Where is the weak link?

IT IS SIMPLE, the weak pilot is the weak link. The pilot must be able to do it all, until the plane is safely on the ground.

Automation can reduce stress and strain in normal ops and assist in emergency ops. This will reduce the need for rest after the flight. BUT a pilot who takes his plane to MAA (max authorized altitude) and can't hand fly it there is fooling himself!

skyhigh:

Can you elaborate a bit on that one?

elaboration


for aterpster:


What I am trying to get at is the ability of some pilots to command their autopilot to climb to the maximum authorized altitude of the plane (service ceiling so the ancients like me liked to say) and would be unable to hand fly the plane at that altitude.

So too, taking your plane into any condition that required the use of autopilot and could not be flown ''by hand''.

to be sure, if regulations require the autopilot to be used (rvsm or Catii apch) you use the autopilot, but you must be able to actually hand fly the plane there in case the autopilot quits.

I think he means no pilot should depend on an autopilot so much that if it fails he cannot safely continue operating the aircraft manually from where the autopilot failed. MAA for autopilot operation should never be higher than where he can properly hand fly. I agree.

Does no-one habitually cruising at Max rather than Optimum ever contemplate the possible ramifications of a TCAS RA ? :confused:

I had the habit of showing FO´s the yoke movement in the Boeing while at high altitude, autopilot ON. The inputs are minimum, over-controlling is common until they finally get the sense of the relationship of thin air /speed and angle of attack. Can´t do that on the bus.:ugh:

Pilot confidence
 

Bubbers at 3156: "I think he means no pilot should depend on an autopilot so much that if it fails he cannot safely continue operating the aircraft manually from where the autopilot failed. MAA for autopilot operation should never be higher than where he can properly hand fly."

There have been a lot of posts to date saying more training is needed. Here are some pointed questions that in 158 pages into 8501 I don't think have yet been asked or answered: Are some current A320 pilots posting on this list suggesting that they personally know other A320 pilots whose skill they consider to be questionable or insufficient to hand fly the AC over any assigned route and altitude? More specifically, would A320 pilots posting here claim they would be comfortable as passengers with any other pilot in their system flying alone in the cockpit at altitude transiting the ITCZ and facing a storm front at night? Are the same airline operators that are hoping to convince the public of transparency and system capability also at the same time not ensuring by sim and actual practice and regular check rides that in the event of control system failure their pilots are capable of flying the aircraft?

I can understand that no one who has reservations would want to state them publicly. However pilots who have full confidence in all other pilots they know should have no hesitation expressing confidence.

Carbon

Did you have passengers on board?

"showing" colleagues new things at the edge of the envelope is not a good idea unless its a properly planned training flight

Sim training is the answer
 

There seems to be so much discussion in this thread about stall recovery techniques that I wonder if there are many out there who don't understand the problem and wouldn't know what to do - some of them Bus drivers. Stall recovery training on the "unstallable" Airbus was like the lifeboats on the "unsinkable" Titanic, not deemed very important. Airline training has concentrated on recovery from an approach to a stall at low level. This is a very different from the situation of the aircraft being in a fully developed stall at high altitude where the recovery technique is quite different. Now that four Airbus aircraft have been lost to stall events (two on test flights), it's clear that crews need to be better trained in case they do experience such a rare event. This needs classroom and simulator training even if the fidelity of the sim is not 100% - it's the drill that counts.

As for the Bus not giving the pilot full control, Bonin had full control available and could have saved his aircraft if he'd used it correctly. He didn't realise the predicament he got into - a full stall - by mishandling the aircraft (in Alternate Law 2, at very high altitude, in turbulence, at night, fatigued, frightened and inexperienced) and didn't know what to do to recover. Neither did his more experienced crew member.

It doesn't help that the Bus doesn't have stick shaker or pusher, so all the more reason to be trained to recognise a proper stall and not to ignore a stall warning unless absolutely sure it is false.

There is a very good YouTube video on Airbus Stall Training.

Yes, the Trident had a pusher. It had to have one because the "T" tail made it liable to get into a deep stall from which there was no recovery! Sadly, on one occasion where it might have helped the crew, it was overridden (presumed false ?) and the aircraft crashed.

Harry,
Carbon made the distinct point that the aircraft was flying on autopilot all the time. What was being shown was how small the yoke movements were by the autopilot. Carbon pointed out that in the 'bus this would not be possible due to the side-sticks and stationary throttles

Fatigued frightened yes. Inexperienced well there are quite a few captains flying around with a lot less hours even in Europe. Something is going fundamentally wrong with training departments. IMHO the authorities have caused training departments to become checking departments. This is because more is asked on an OPC LPC & the airlines do not want to pay for more training time.

Well,I've followed the thread and its been an interesting read and there have been some excellent contributions,in particular Retired F4.I dont know the Airbus so I cant comment but it seems to me pilots have to know as a memory item just what each different law implies.Precisely.They cant respond to a UAS/Stall/Upset without knowing just what level HAL is operating under and what that means to them as the pilot.Do they have trim all the way nose up,do they have to trim out of the stall themselves,etc etc.The points about the small SS,non-moving throttles,silent stabtrim all make it a high tech spaceship in Normal Law but I dont think its my kettle of fish when things go pear shape.

But for me,its about the pilot,not the Bus.The changing face of the airline pilot.Ive done a fair few contracts in my time after leaving my first and favorite airline,Dan Air.And I can tell you that on joining 80% of these airlines,nobody really cared about my flying skills or airmanship(bar the V1cut and required LPC items).What they all cared about was...did I know and follow the SOP's,cross my T's and dot my I's,and keep the automation in and watch the good ship.I rarely if ever saw sim time devoted to ex LPC items.And many instructors would reposition the sim in a perfunctory manner until the box was ticked.No expansion,no discussion,no focus on airmanship.Just whats the next box to tick.
In one airline I was supposed to follow like a monkey a set pat of intra flight deck comms when the ramp agent arrived.:{I said to the line instructor,I can get the loadsheet,extract the data,enter it into the FMC with the other guy cross-checking and we can do it safely without a procedure like a monkey.This is where the airlines focus is now.Procedure.They dont want the crew thinking for themselves or flying the plane all by their lonesome.And its enforced from top down with FDM.This is where we're going wrong.This is why we get 447 and the Asiana.No basic flight skills.And its not the pilots fault.Its the people running the show that are to blame.You need old stick and rudder guys running the show in the training dept,not SOP guys.
My instructors in Dan Air were old timers and they taught me how to fly.I picked up the mundane procedures as I went along,how to do a howgozit,how to handle the comms,what section of the COM to find the holdover table etc,etc.But their focus was basic flight skills and airmanship.Their mandate was to pass that knowledge on to the right seat.They didnt give a monkeys if I got a procedure(there werent many in those halcyon days anyhow) the wrong way round just so long as I knew my pitch and EPRs for 250/210/170,I could handlfy a raw data ILS in marginal,I knew my way round the engineers panel,and I showed enthusiasm and wanted to learn what they had to show me.FOs arent like that anymore are they?They know it all already.CRM tells them theyre all entitled to equal measure.:{Look at Bonin,he knew all about the ITCZ,all about the smell of ozone,all about St Elmo,all about how to fly didnt he?And now all those people are dead.And why?Its not Bonin.Nobody taught him anything in those 3000 hours.All he knew was procedure,the facade of being an airline pilot.
So whilst the Airbus definitely has some funny quirks(that latest AD OMG),whats needed is a return to flying.Fly the plane.Pure and simple.Airmanship is what will save this troubled profession.Sounds corny and old hat but its so true.Procedure last.SOPs enable 2 strangers to operate a complex piece of machinery.They have an importance but its tertiary.
Thats my take on this sorry state of affairs in our great profession.Over and out.

Doesn't sound corny at all...but simply illustrates the problem with too much automation. In the end they inhibit basic airmanship.

Cockpit Crew Seated/Belted?
 

I may be behind the power curve and if so sorry, but has any definitive confirmation been made as to where the crew was prior to contact with the water. So many media accounts recently saying a myriad of stories quoting officials close to the investigation, but unless I am mistaken, no "official" yea or nea has been declared. And do we know for sure that the Capt left his seat before the onset of control loss.

By reverting to the inertial reference system (IRS).

I can understand why AB would not want to use IRS data for normal law, to define a stall, it could easily be used for alternate law.

The IRS knows the attitude (after all, that is what we fly by) and it also has a good idea about the airspeed.** And the FMC knows the weight. From this, the correct stall attitude can be calculated with reasonable precision.


** The IRS and FMC know the groundspeed, while FMC knows the previous windspeed and altitude from before a problem occurred, and can use this to calculate a probable TAS airspeed. The FMC could also integrate known thrust, attitude and altitude, to derive a secondary airspeed profile.

What Law Are We In?
 

In the AB is there any kind of information displayed that tells the pilots which law the system is operating in? A light? A message displayed?

Would it have made any difference to AF447 if there had been such a notification? Would anyone have acted differently?

Well, not really...but most of the time. This statement presumes no vertical up/downdrafts...which probably has a lot to do with this accident. Might have helped with AF447, but don't see how that would help in this case, in fact keeping it within a prescribed pitch attitude could make the situation worse.

Something like this:

ECAM gives details
PFD shows icons reflecting degraded protections.

Alternate
Amber XX's replace the green attitude limits on the PFD.
The PFD airspeed scale is modified:
- VLS remains displayed
- VALPHA PROT and VALPHA MAX are removed, replaced by a red and black barber pole, the top indicating the stall warning speed VSW

Direct
An amber message USE MAN PITCH TRIM appears on the PFD.
The PFD airspeed scale remains the same as in Alternate Law.

Mechanical Backup
A red MAN PITCH TRIM ONLY warning appears on the PFD.

This fits into the current legal environment nicely. That is what has a lot of management concerned: liability. This make regulators happy, seeing all of those boxes ticked. Training costs time and money. Box ticking is more "time efficient." (Please note the sarcasm dripping from my keyboard ... )
ISO 9000 has arrived on the Flight Deck.

Don't feel bad. This isn't only a problem in the airline industry.
Because people are hard to lead and manage.

@ wes wall - cockpit crew
 

Status that I keep says ...

Both Captain and F/O were seated.
Early rumours that Capt was out of his seat were rejected early on by officials.
Rumours persisted.
No foundation of rumours known to me.

On Friday both pilots were located in the damaged cockpit. Both strapped in. And one of the pilots was recovered. His uniform had 3 stripes. But formal identification is referred to the DVI team.

Recovery of the second pilot, most likely the captain, is planned. Progress unknown.

Perfect summary caulfield & Lonewolf_50 adds to it nicely! The accountants & marketing types have got their hands firmly on the airline industry & they are going to force it into their mold, no matter what!

Alternate Law PFD
 

Note the HUGE red X's on the display in Alternate Law PFD


Flight Control Laws | Alternate Law - Description

Caulfield
 

Not much to add,even today. thanks for writing.