Air Asia Indonesia Lost Contact from Surabaya to Singapore

[Oakape]

Physicus, don't throw insults if you're not going to get is all right - adding power at high altitude is always going to be a gradual affair as the engines respond slowly up there. They also have relatively little thrust in the cruise due to the low air density, so aggressively firewalling the thrust levers from a high alt stall is not going to be the source of control issues and will be easily overcome by elevator pressure, especially if you remember to trim. Low speed and low altitude and yes, it is a major issue.

Aluminium shuffler, while I agree with you regarding thrust at high altitude, how can the following post by silverstrata be explained?

Likewise the high altitude stalling was interesting too. With the engines at full chat (as commanded by the a/t) it was almost impossible to recover from the stall. And at cruise power, full forward control deflection was required. It was useful to learn that the standard light aircraft nod into a recoverable descent just did not happen, and the aircraft would just pancake down almost tail first - just as AF447 and this one did.

Is it a case of lack of sim fidelity or is elevator effectiveness reduced at high altitude by approximately the same amount as the available thrust is reduced?

[tubby linton]

Nigel the latest stall drill in the QRH states--


NOSE DOWN PITCH CONTROL APPLY
This will reduce angle of attack
Note:
In case of lack of pitch down authority, reducing thrust may be necessary.

[silverstrata]

Nigeldraft:

"Stall Warning on Takeoff" is an A320 Memory Drill, and taking the power off I cannot recall as part of the drill :ugh: In fact, the complete opposite is the case ;)



Agreed, but then so would a stick pusher be inconvenient at that point in the flight - but that did not stop stick pushers being added to aircraft. And the last stick pusher I had was quite forceful - ten kilos of push perhaps? Anyway, it was nearly capable of taking the stick out of your hands if you were relaxed.

Likewise the stick shaker which I had go off on rotation, that can be disconcerting too (especially on a 2,000m runway). Am I at the right speed?? Gets the ticker ticking.

Besides, it is not beyond the ken of Airbus engineers, to put a 2,000 ft altitude limitation on the proposed power-reduction-at-stall protocol.

[silverstrata]

Oakape:

Is it a case of lack of sim fidelity or is elevator effectiveness reduced at high altitude by approximately the same amount as the available thrust is reduced?


Two factors.

Firstly, this was a stalling demonstration in the sim, so the aircraft was very slow. We might have been back at .62 mach or so, or about 180 kts IAS at 39,000 ft. Remember that with underslung twins, the thrust can overpower the elevator at low altitudes. Yes, there is less thrust at altitude, but that thrust is still opposing the required elevator motion.

Secondly, it is not simply the lack of elevator authority, but the stick forces required (not Airbus). The force required to push the stick forward was surprisingly high and counter intuitive. Normally at altitude the stick is very sensitive, so the need to push with both hands was not usual for that altitude, and could be confusing.

And that is why we do these demonstrations in the sim.

[Aluminium shuffler]

Oakape, I have done the high altitude upset exercises several times in the 737 800 sim and not found any issue regarding flight control effectiveness. The force needed on the elevator will be large if trimmed nose up (for the reducing IAS prior to stall), but that is no different from at any altitude, but even without trimming, I didn't find any problem. I'm not a sportsman and never go to the gym, though I'm not a couch potato either - I just live an active lifestyle. So, a 5' waif may have trouble, but the average male pilot shouldn't have any issues. I can't speak for other types, though.

[Aluminium shuffler]

The Ancient Greek:

My guess at why several stalls have been maintained or exacerbated by pilots hauling back on the column/stick is that it is human nature when scared to grab and pull tight. However, it does show that these individuals and many, many more don't have the appropriate training or experience to overcome that primal instinct. I think removing spinning and aeros (or at least reducing the amount done) and reducing the stalling exercise amount in licence training (at all levels from PPL to ATPL) is a big mistake. I can't help feel that a large amount of training at the edge of the flight enveloppe would sharpen trainee's handling and hone the correct reflexes.

Tdracer - I understand what you're saying about the aural stall warning in 'busses, and agree. Unfortunately, its not possible to fit stick shakers in those crappy little side sticks. I like the idea of a side stick, but I'm horrified that they have no feedback of any sort from the autpilot or other stick. That is a lethal design flaw. I will always be convinced that it is a principal factor in both the relevant accidents and will kill more people yet because the pilot who understands what is happening to the aircraft doesn't realise what the other pilot is doing to the controls, assuming basic competence of not holding an ac in the stall.

[mickjoebill]

Do bus pilots agree that given the amount of publicity hiven to these two accidents, that they should be able to identify and correct a high altitude stall?

Can further accidents of this type be prevented by vigilance alone?

[Jet Jockey A4]

Thank you for that link on the Boeing/Airbus stall presentation it was very interesting.

I only wish we could have a similar presentation for T tail/aft mounted engine aircrafts (which I fly) to see the differences.

It was interesting to hear them say that under all stall condition a "lowering of the nose" was mandatory to reduce AOA, that you should not roll out and lower the nose of the aircraft at the same time (overstress the tail) but lower the nose first then roll out of the turn and finally not to increase the power but wait until establishes in the recovery prior to slowly increasing the power.

Finally it seems that Boeing with its 787 was moving toward Airbus' philosophy when it comes to FBW.

[RetiredF4]

silverstrata (Bolding by me)

In normal law, an Airbus should never enter this state, but in alternate law it certainly can (as can Boeing twins). There is no reason why a stick pusher or a thrust reducer cannot be applied in these cases, where the aircraft is in alternate law. A thrust reduction at the point of stall, will lower the nose quite sharply (if the stick is neutral or forward of neutral) and make the exit of the stall relatively simple.

That statement of yours is imho misleading and does not reflect the correct procedure. A neutral stick in the bus commands a loadfactor of 1g, and would therfore force the aircraft in a decreasing speed environment due to power reduction in a higher AOA, the elevators and the THS may drive all the way nose up to achieve the commanded 1g. Same would happen with slight nose down input, as the increasing rate of descent in a stall would be felt by the sensors as less than 1 g, and the commanded g by a slight SS forward might be bigger, thus still the flight surfaces would be positioned for a nose up flight path. With such SS inputs the aircraft would be forced deeper into the stall and into high AOA. Bonin demonstrated how it would end. I'm not saying it might not drop the nose finally, but it might do it only in a very high stall state. And such a mistrimmed aircraft with the elevators and THS all nose up will be a definite handicap during recovery. It may even be the recipe for secondary stalls, as the increasing speed after a possible nosedrop could cause a pitchup again if not countered by manually trimming nose down and using amounts of SS forward to counter it.

So wy would you let this happen in the first place?

There is only one correct stick position as early in the stall as possible concerning the SS and especially in a flightpath stable aircraft like AB: Put the SS forward (and i would even say full forward) until the AOA is reduced to normal values and speed has reached flying airspeed.

We discussed that in the AF447 thread quite extensively, but this misjudgement of the effects of the flight computers under C* striving for the SS commanded g on the elevators and the THS trim from AB qualified crews is astonishing or even alarming.

[misd-agin]

1. Current simulator modeling DOES NOT give an accurate replication of jet airliner stalls, especially at high altitude. Both Airbus and Boeing say stalls in the a/c are more violent. They've recently agreed to a simulation model that works for n/b a/c (but not w/b's) that we might get to experience in a couple years.

2. You'll rarely see more than 5, or perhaps 6, degrees NU in an airliner above FL300. You need a v/s of greater than 2000-2,800 FPM to see pitch attitudes that exceed 5-6 degrees NU.

[RatherBeFlying]

Davies did a long writeup on the certification requirement for stick pushers in T-tailed a/c.

The pushers were required in these a/c because the stall was unrecoverable.

Pushers are not required in a/c that can recover with standard pilot actions.

We are seeing high altitude stalls all the way to the ground and not just in Airbii - there's also at least one single engine turboprop I know of

To recover from a stall in an a/c certified as able to recover, you must first recognise it, then take appropriate corrective action.

Recognition becomes harder when the a/c settles into a steady state as with AF447 for which we do have data.

Certification requires the stall be recognisable. The nose drop has been superceded by aural warning, but as others have pointed out the human brain can shut down the auditory channel in high stress situations. I was in a simulator when the other pilot went inverted at 16,000' (white on black AH) and kept it there while I was shouting in his ear all the way to the ground.

What still bothers me about Brand A is that so far I have not heard of any test flights to determine stall behavior and recovery at any altitude.

Brand B seems to recover from high altitude stall events, but I have not come across any discussion that Brand B does stall test flights even though prevailing sentiment is that they likely do.

[Capn Bloggs]

Brand B seems to recover from high altitude stall events
Would it, if the stab trim was wound fully back, the speed brought back to less than 100kts, with full power on and descending fast?

[xcitation]

Something more radical is required rather than the apparently easily ignore audio "stall", cricket, and warning lights.
If we are able to identify the stall from the FDR then the system can be programmed to know how to identify a stall upset. Why not program in an automated stall recovery once it has fallen like a rock 5'000. Allow the pilot to over ride but have "rescue mode" activate automatically. At that point the a/c is likely lost anyway. This could optimize the nose down and application of power to the best recovery.

[FDMII]

With reference to post #3021, superstrata,
A deep stall is any stall that cannot be remedied with elevators....and that character of a deep stall is almost exclusive to T-tail aircraft, but I prefer not to quibble over definitions, I'm more interested in characterizing and understanding stalls in which there remains some elevator authority and which, in transport aircraft, may be recoverable.

[Capn Bloggs]

No, instead of clamouring for more technology to fix the problems created by technology, train the drivers better. 30 minutes buzzing around on raw data (including wingovers, steep turns climb/slow/turn exercises), with 15 minutes of eyes-closed UA recoveries. This will reconnect pilots with the aeroplane so they will be better able to 1/not get into a handflying disaster aka AF447 (and perhaps 8501) and 2/be able to recognise that they are in a stalled state, regardless of how they actually got there, aka AF447, and recover.

And of course remove hand-flying auto trim!!

[scard08]

One thing I dislike about [...] use of a verbal "STALL, STALL" (instead of a stick shaker) is that humans have a tendency to filter out aural inputs when concentrating or highly stressed. Meaning the STALL warning may not even be heard when it's most needed.There is an interesting quote in this article (http://www.scmp.com/magazines/post-magazine/article/1491534/pilots-reveal-death-defying-ordeal-engines-failed-approach) from the pilot of Cathay Pacific 780 who after other severe trials had no control over engine thrust whilst landing and so came in extremely fast ... he said

“At that point, we started getting a lot of warnings going off in the cockpit, too. The cockpit started to become a very noisy place. All the systems are built into the airplane to warn you you’re approaching a dangerous area … the warnings were coming so thick and fast they were going over the top of each other.

“I had to put them all to one side, ignore them, and concentrate on what I thought was the most pressing issue, and that was to get the airplane on the ground as close as possible to the end of the runway.”Which turned out safely for all involved. :)

Problem is, I'm not convinced that a stick shaker is much better - I can think of at least two [...] crashes where the pilot pulled back in response to an erroneous overspeed indication and stalled, then apparently dismissed the stick shaker as 'Mach buffet' due to the perceived overspeed.A glider pilot much earlier in this thread mentioned that his stick would shake as an indication of a stall because the lack of clean airflow over the control surfaces. It was a direct mechanical link from the fluttering surfaces to the stick.

I know it's not a direct link in a transport. But does that mean that both edges of coffin corner provide the same cue to the pilot when different responses are required?

Given the choice between the two (and I realize never getting there is the best option) is exceeding the mach limit more recoverable than the stall at cruise altitude?

[_Phoenix]

...Same would happen with slight nose down input, as the increasing rate of descent in a stall would be felt by the sensors as less than 1 g, and the commanded g by a slight SS forward might be bigger, thus still the flight surfaces would be positioned for a nose up flight path. With such SS inputs the aircraft would be forced deeper into the stall and into high AOA. Bonin demonstrated...
RetiredF4,
You nailed it right in the sensitive spot :D
FBW software should ensure safe algorithm operation during entry into and recovery from a stall condition, THS trim function should be inhibited in the NU direction at a position that assures adequate stick/elevator control authority for stall recovery, even at full thrust. THS trim should be inhibited well before stall, based on AOA or speed margin above 1g-stall speed or esspecially if SW is online.
Brand B seems to recover from high altitude stall events
Would it, if the stab trim was wound fully back, the speed brought back to less than 100kts, with full power on and descending fast?
Capn Bloggs,
The force needed on the elevator would be large for THS NU, but it isn't any problem and there is the "feel" for need to trim forward.

[Capn Bloggs]

The force needed on the elevator would be large for THS NU, but it isn't any problem
Isn't any problem? I doubt any fully-stalled aeroplane at slow speed and 40° AOA could be recovered using only full forward stick with a full back-trimmed stab.

and there is the "feel" for need to trim forward.
in the heat of the moment, when you never use the trim normally, I doubt very much whether you're going to remember to do it.

[_Phoenix]

Isn't any problem? I doubt any fully-stalled aeroplane at slow speed and 40° AOA could be recovered using only full forward stick with a full back-trimmed stab
40° AOA is quite extreme and not sustainable, but with THS at 25°-30° AOA, reduced thrust, the elevator at max ND would give a ND momentum

in the heat of the moment, when you never use the trim normally, I doubt very much whether you're going to remember to do it.

That's true for Perpignam, but in 4.5 minutes...

[xcitation]

@Capn Bloggs

It makes sense to have both. The tech needs to be constantly improved and refined. Always agree with more manual training and I would modify the certification for type to include a more significant manual flying quota. Otherwise there would be no incentive for it to be done.

[John_K]

As a GA pilot who relies on stick and rudder skills. have been following this thread and feel quite concerned, even though obviously the results of the investigation are to be made.

I am concerned because there are perhaps some RPT Airline crews out there may have forgotten their basic training from the first 20 hours of their original flight training on:

1. Stall recovery - concerned that it appears that alarms about the Air Asia plane stalling were blaring for like 3 minutes - was the basic stall recovery of push the stick or column down/forward to reduce the AoA totally forgotten? including the use of the rudder to unstall a wing?

2. Taking care or avoiding flying through thunderstorms - when we all studied MET what were we taught? Thunderstorms have incredible energy that can tear an aircraft apart - concerned that tight time schedules and familiarity have bred contempt for these powerful weather phenomenon. As others have said, then Airlines crews decide to become Test Pilots it will eventually lead to disaster.

3. Over reliance on automation - too many systems designed to reduce workloads - what about actually knowing how to fly the plane without these? Today's aircraft are inherently more stable, less likely to stall and designed to be smoother in flight but it all can come apart if we let a computer pilot us rather than us piloting the plane.

Hope there are some good learning out of this tragic accident and the loss of life has not been in vein and contributes to improved safety in the RPT Airline industry.

[Volume]

The accepted definition of the "deep stall" or "super stall" is that of Davies', which refers solely to the blanked T-tail designs. The term "deep stall" (and the phenomena) already existed at least 3 decades before the first T-Tail was invented.
Basically what it means is stable flight in the region between the first Clmax (around 10° AoA, depending on the airfoil and configuration) and the second Clmax, which naturally occurs around 45° AOA for every airfoil. There is always a second "post stall" region of positive Cl over AoA slope, and if the horizontal stabilizer allows to get there, the aircraft can be flown stable in that region with lift and drag of similar magnitude, hence with flight path angles somewhere between 30 and 45 degrees. Depending on the overall design this condition can be so stable, that elevator efficiency is not enough to get out of that. The T-Tail is the most often occurring example for such configurations, but not the only one.
BTW, deep stall with T-Tails is not stable with the Tail in the wake of the wing, but with the Tail on the rear boundary of the wake. It is not so much because the elevator looses efficiency, it is because the flight condition is so extremely stable if any pitch up results in the tail leaving the wake and hence producing lift again and a nose down pitching moment, while pitching down results in the tail fully entering the wake and hence producing less lift and a nose up pitching moment. The Cm curve is so steep in that region, that shifting it up and down due to elevator deflection does not change the pitching moment significantly.
Canard configuration aircraft can even have stable deep stall around 230° AOA (inverted backwards...) as discovered during the SpeedCanard flight test...

[RetiredF4]

Quote:Phoenix
40° AOA is quite extreme and not sustainable, but with THS at 25°-30° AOA, reduced thrust, the elevator at max ND would give a ND movement.

But remember, under FBW C* implementation like AB in normal and alternate law the SS does not control the elevators directly. A SS neutral does not command an elevator at neutral position, it commands a loadfactor of 1g and the elevators and THS will be at whatever it takes to maintain or achieve this 1g. In a stalled condition like you describe with the THS all the way nose up the elevators would be nose up too.
The SS commands a loadfactor change, which the Flight computers will transfer into an elevator command with gains designed for comfort and in order not to exceed the loadfactor limitations. So it will take a long time SS full nose down to get those elevators moving beyond the neutral position into nose down, and only then would the trim start to follow and start to trim nose down. There is no time to wait for that. Use the procedure which is established, and that one includes the use of manual trim.

[wiggy]

Brand B seems to recover from high altitude stall events
Would it, if the stab trim was wound fully back, the speed brought back to less than 100kts, with full power on and descending fast?

Well, FWIW on at least some of Brand B's FBW aircraft stab trimming is inhibited below (approx) min manoeuvre speed.

[bubbers44]

When a tail loses lift the nose pitches down because the horizontal stabilizer pushes the tail down for stability.

[RetiredF4]

bubbers44
When a tail loses lift the nose pitches down because the horizontal stabilizer pushes the tail down for stability.


True for an unstalled aircraft, different for an aircraft in a deep stall situation due to different reasons like shift of center of pressure, .......

[silverstrata]

F4

A neutral stick in the bus commands a loadfactor of 1g, and would therefore force the aircraft in a decreasing speed environment due to power reduction in a higher AOA


You have a stick that commands 'g' instead of attitude??? Who invented that idea? Anyway, surely that is not true in alternate law, it must default to attitude. Yes, no? Surely it must.

But what I said stands true for conventional controls. A good aircraft should always lower its nose in the stall even with the stick neutral. If not, you have the CofG - CofL couple incorrectly positioned. (But see also below.)




Ratherbe:

The pushers were required in these a/c because the stall was unrecoverable. Pushers are not required in a/c that can recover with standard pilot actions.


But this is the question. Is the stall recoverable if the thrust has been left at maximum?

The stall is certainly not recoverable on the 737 (for instance), at low altitude with the engines at max, as was amply demonstrated a few years back on an ILS approach. But what about at high altitude? Ok, thrust may have degraded to about 1/4, at 35,000 ft, but that is still a lot of pitch-couple for the elevators to overcome. So will it recover from the stall at 39,000 ft, with engines at max? My last sim run at this a few years back demonstrated that an underslung twin was reluctant to unstall at full aft CofG at best, and that was not using full chat (we had reduced power, to create the stall).

And if the stall is not easily recoverable with engines at max thrust, then why no stick pusher? (Or why no auto thrust reducer....?)

[Sop_Monkey]

Bubbers 44

"When a tail loses lift the nose pitches down because the horizontal stabilizer pushes the tail down for stability."

If the THS is also stalled and thrust is keeping the nose up (high AoA), will that still be the case?

[NigelOnDraft]

tubby linton Nigel the latest stall drill in the QRH states--

NOSE DOWN PITCH CONTROL APPLY
This will reduce angle of attack
Note:
In case of lack of pitch down authority, reducing thrust may be necessary.Suggest you re-read my post re the drill I referred to, and QRH. Mine says "TOGA and set 15nu"...

[Vilters]

TOGA and pushing nose down on the stick will get you nowhere in some deep stalls.
The 2 moments neutralise ach other.
The engines lifting the nose, and the tail pushing nose down.

The remaining vector is ZERO and the only velocity is going vertical down till impact.

Stalls come in lots of forms and shapes.

Prio ONE is to get the nose down.

Stick, closing of throttles, trim to nose down, all tools are good tools to get the nose down.

But you have to get them all working together.

At FL, this can take several thousands of feet.
But PRIO ONE is to get the nose down again. Even if it means dropping the gear in airplanes that allow it in the higher FL.

Never mind a missing door, if it can get you to regain control of the aircraft.

[tubby linton]

Nigel my post was a straight lift from the FCOM regarding a stall warning(not at take off) .
At Take off it is as you say Toga ~15

[Volume]

When a tail loses lift the nose pitches down because the horizontal stabilizer pushes the tail down for stability. Actually it is not for stability, but for moment compensation. The moment compensated is the nose-down pitching moment produced naturally by any cambered airfoil with attached flow. So when stalled, this pitching moment may disappear, and no more downforce on the tail is required. But that depends heavily on the specific airfoil characteristics, whether the flow separation starts at the trailing edge and extends forward, or whether it starts at the leading edge and reattaches further aft.
At 30° AoA there is no way to produce a down force, no plain flap (used as elevator) is that powerful and nobody would be insane enough to allow a stabilizer trim to move 30° nose down (relative to the fuselage). And as for a swept wing the outer wing is stalled first, there is so much nose up pitching moment that you need lift on the stabilizer to maintain stable flight.
Which however is not always desirable, as stable may mean unrecoverable, so you may prefer to lose control and start again by recovering from there.
Also the characteristic nose drop at stall is produced by the lift produced at the horizontal stabilizer at high AOA.

[NigelOnDraft]

Nigel my post was a straight lift from the FCOM regarding a stall warning(not at take off) .
At Take off it is as you say Toga ~15 Thanks ;)

It's all a few posts back now, but was in response to a suggestion that a Stall Warning generates an automatic power reduction :{

[FLEXPWR]

Silverstrata,

To my knowledge, no commercial aircraft is ever directly "commanding" an attitude with either a stick or control column.

Conventional aircraft command a pitch change (or attitude) by deflection of the elevator.
Airbus FBW aircraft side stick orders command a g load which, through various flight computers, move the elevator accordingly to give the demanded g load, until the stick is released back to its neutral position, then 1g (corrected for pitch) will be maintained again, until a new input is made on the side stick.

This is valid in pitch both in normal law and alternate law. Roll is another story.
Only direct law will provide a direct relationship between elevator and sidestick longitudinal movements, though not in a strickly linear fashion.

For the rest of these wonders of aviation technologies and why it was designed this way, I recommend that you spend some time in the Tech Log and get a good grip with the concept of Airbus FBW before suggesting this is nonsense, or why would anyone design such a thing.

[HarryMann]

Well I hope Volume will agree that a lot of swept wings are doctored
to force a root stall first so the mainplane itself contributes to
nose down (-) in and of itself.

[sky9]

I have always been fascinated by the position of the wing on the A320 compared to the 737. It appears to be further forward which would suggest to me that the downforce on the stabilizer of the A320 is less than the 737. If that is the case the aircraft would have less of a natural recovery from the stall than the Boeing. Any thoughts?

[Msunduzi]

I have always been fascinated by the position of the wing on the A320 compared to the 737. It appears to be further forward which would suggest to me that the downforce on the stabilizer of the A320 is less than the 737. If that is the case the aircraft would have less of a natural recovery from the stall than the Boeing. Any thoughts?.............................................


Maybe they have fatter pilots.

Doesn't matter where the wing is in comparison, where the CoG is that matters, and to the CoP

[Lazerdog]

Anyone know what the transit time for the the elevator auto-trim is from the full 13 degrees up back to neutral on the -320 when pushing full forward? That delay is problematic when the brain is racing to solve a problem and acting faster than the systems on the A/C.

[RetiredF4]

I think problematic is not the time of travel of the THS trim, it would move quite fast (when it is commanded by the computers to move) however that depends on the present loadfactor and speed and the gains, and I think there are more factors going into the flight computers which finally position the elevators and move the trim.

More problematic seems to be that pilots over all brands avoid considerable loadfactor reductions to below 1 g by all means, which is good for load comfort during normal ops. Minimal loadfactor reduction below 1 g is only present during day to day ops when initiating a descent or doing a level off after a climb. I trained military pilots in air combat maneuvering, and even this breed is very reluctant to use agressive nose down stick inputs and the more when this input should be maintained for more than a second in the range of 0 to -1g. It has to be trained into them that they gain confidence in the outcome of such inputs. Sure it comes handy to be strapped into the seat and having no meals fly around.

Therefore in a stalled situation it is a total untrained and uncomforting maneuver to put the SS or the control column full forward until the aircraft reacts to the input in the desired way. Looking at the FDR' s from some stall accidents will show my point. It is the thinking " a neutral or slightly nose down input will do the trick" and "negative g's will kill" which is the elephant in the room in failed stall recoveries.

I think especially Airbus crews could do that maneuver without much thinking, as the loadfactor protection is operational in normal and alternate law and should protect the aircraft from too much negative g's. Let the system work for the benefit of a fast and quick recovery instead of taking the chance that it works against this intent. And if the full forward stick does not lead to the desired reaction, feed in manual trim.

[Jack of All]

I have recently undergone the Upset Recovery Training developed specifically to train airline crew to recognize and recover from extreme upsets and Loss of Control Inflight ( LOC-I).

I am an Airbus TC on the 320, and I must say, after that program, we are staring at the biggest threat to airline ops completely wide-eyed and unprepared.

This totally redefines the concept of unusual attitude recovery. Hugely.

Thank heavens this has actually been developed, refined and is now actually being implemented. Google UPRT and have a look at the excellent documents available.

Let your management know in no uncertain terms that this must form part of your recurrent program THIS YEAR.

Push. Roll. Power. Stabilize!

[Rananim]

So it will take a long time SS full nose down to get those elevators moving beyond the neutral position into nose down, and only then would the trim start to follow and start to trim nose down. There is no time to wait for that. Use the procedure which is established, and that one includes the use of manual trim.

Wow..This autotrim design is at the heart of it.The USE MANUAL TRIM didnt work for test pilots at Perpignan,it will hardly work for the LCD will it now?
If I handfly a B,I rest my thumb on the trim switch.Automatically.I dont think about it.Its a motor function.

An Airbus pilot can probably go a whole line career and never invoke law degradation and so never trim manually except twice a year in the sim.How easy then might it be to forget to use manual trim in a stall with no stick shaker and only that useless "stall,stall" going?Aural warnings get filtered out under stress.ECAM advisories,twenty at a time,not much good either.No stick shaker.Well,there isnt a stick...Nothing tactile,best channel of all under stress.

Trim down,stick down,reduce thrust mid-position..Just how difficult is it?Why the confusion?What can be done?

[RetiredF4]

@Jack of all

Thank you for that link.

Now after all these years of discussion there is hope....!

[.Scott]

Correct me if I'm wrong, but there are only two ways that the Airbus could have climbed as rapidly as it did: with severe and persistent up elevator or with CG way too aft. We have reports that the CG was well within limits. So that leaves severe and persistent up elevator - something that should not be allowed by the FACs. So we have a problem with either the FACs or the elevator itself. It is reported that both FACs were reporting a fault and that the stall warning was sounding. So it would appear that the FACs "knew" something was wrong and that the plane was in a stall. From this thread, it is reported that the FACs respond to a stall condition by increasing thrust and applying down elevator. It is possible that the FAC software failed in this simple duty, but I would bet against that. Also, if the main problem was with the FACs, then cutting them out should have made the flight recoverable by ATC pilots.
That leaves the elevator itself. If the pilot started a climb, the elevator may have visited a severe up position. If the elevator got stuck in that position, the FACs would signal a fault and the plane would attempt an inside loop and enter a dramatic stall.
But why would the pilots take out the FACs that were already trying to get the elevators into a nose down position? So that they could do something that the FACs were not programmed to do - attempt to shake the rudder free.

Please feel free to poke holes in this notion. That's what I've posted it for.

[HarryMann]

True Rananım
Haptic feedback is good. Doesn't get filtered out too easily
witness being tapped on the shoulder repeatedly... annoys!

[Sop_Monkey]

Jack

So good to hear there is actually recognition now of an old problem. How many years and lives lost too late?

This delay is nothing short of criminal.

[skippybangkok]

When a tail loses lift the nose pitches down because the horizontal stabilizer pushes the tail down for stability.
Actually it is not for stability, but for moment compensation. The moment compensated is the nose-down pitching moment produced naturally by any cambered airfoil with attached flow. So when stalled, this pitching moment may disappear, and no more downforce on the tail is required. But that depends heavily on the specific airfoil characteristics, whether the flow separation starts at the trailing edge and extends forward, or whether it starts at the leading edge and reattaches further aft.
.

Actually it is for stability....modern jets are still aerodynamically stable.. I have done the hours and hours of heavy calculations. In essence your wasting fuel ( big wing pulls up, tail down ) by this downward forces, but it's the only way to make the AC naturally stable without computer systems as in fighter jets

[Leightman 957]

In the early 80's I believe NASA did some testing of deep stall characteristics using a single place T tail Schweitzer 1-36 which was modified to permit the horizontal stab to angle nose down to about 45 degrees. The pictures of tell tail streamers angled up about 45 degrees to the wing mean chord in a steady stable descent was arresting. I don't recall any longer whether a single angle of descent was explored or whether the H stab was capable of various nose down settings allowing a variety of descent angles to be investigated. But the point was that a stable controlled descent in a fully stalled condition, well in excess of the perhaps 13 degree Wortman airfoil stall AOA of the 1-36 was achieved. And, importantly, was repeatedly recovered from.

There have been quite a few (not necessarily connected) posts now from pilots apparently familiar with the A320 suggesting that a combination of thrust moment, auto fly to G, mode of readouts, lack of pilot SS feedback, narrow speed margin, warning chaos, and possible rapidity of AOA change in relatively rare turbulence, not to mention pilot error (however small) and confusion over what the control system is thinking could ALL have contributed to two accidents where a stall all the way from altitude to impact occurred. There are more recently some hints (and counter opinion) that, once stalled, the A320 control system might actually be attempting to hold the plane in a stall.

A few posts have argued about whether the horizontal stab and elevator act to counter wing airfoil pitch moment, or to produce dynamic stability which is to a degree needlessly confusing because both moment forces and dynamic stability are involved. But those posts did not mention (and I don't think anyone has) running a relatively aft cg via fuel transfer to reduce drag by streamlining the Hstab/elevator, for fuel savings of course. I would appreciate some better detail from an A320 pilot on 1) whether and to what degree fuel transfer is used to supplement aerodynamic trim, 2) at what point in a flight is fuel transfer usually performed, 3) if fuel transfer is employed, is there an SOP for reversing that transfer in anticipation of encountering a storm line, and 4) wqhether the FDR would record fuel transfer events. Running on the ragged edge of an aft CG, even if inadvertant, of course would not be the best situation from which to begin an altercation with bad weather.

Jack of All, thanks for that post. How rapidly is the training you took being distributed through the entire pilot complement?

[toffeez]

I usually get modded out, even when I'm being constructive like now.
Someone will no doubt correct me, but I don't think the A320 has a wet tail.
So how to vary c.g?

[PT6Driver]

Silver

The stall is certainly*not*recoverable on the 737 (for instance), at low altitude with the engines at max, as was amply demonstrated a few years back on an ILS approach.*

If you are refering to Turkish at AMS then the lack of recovery was more late recognition and inappropriate recovery techniques as I recall.
However the Bournemouth b737 incident shows quite clearly the effect toga has on the pitch attitude along with the fact the aircraft trimmed for slow speed. They recovered thankfully!
If your point is that maintaining max power makes the situation unrecoverable then yes, they did not recover until power was reduced and elevator authority regained.

[silverstrata]

Jack:

I have recently undergone the Upset Recovery Training developed specifically to train airline crew to recognize and recover from extreme upsets and Loss of Control Inflight ( LOC-I).


I am surprised. I did mine on the 737 ten years ago. (But not enough retraining, I think.)

Why so late?

[silverstrata]

Flexpwr:

To my knowledge, no commercial aircraft is ever directly "commanding" an attitude with either a stick or control column.



I'll see your confident gambit, and raise you ten....

The 737 in CWS mode does exactly that - it commands and maintains an attitude (always in pitch and sometimes in bank). And CWS is controlled by the control column. Which is why I thought the A320 must be doing the same type of thing.



Flexpwr:

I recommend that you spend some time in the Tech Log and get a good grip with the concept of Airbus FBW before suggesting this is nonsense, or why would anyone design such a thing.


If you hold a constant 'g' with a decreasing speed the system will require an increasing pitch attitude to maintain 'g'. Conversely, holding an attitude will merely hold a constant attitude. The first design will get you into trouble before the second.

Any other questions?

[Leightman 957]

A320 does not have an aft fuel trim tank. However to amend my earlier post, A320 CG does move with fuel consumption. So my question for Those Who Know remains somewhat the same: Would cg changes due to fuel burn in any way exacerbate the set of conditions already being discussed resulting in an unsustainable climb?

Quote “nice to know.. but in A320, CG always move backward with fuel consumption, irrespective of the tank..” at 13 Aug 2011 at:
fuel consumption and CG movement [Archive] - PPRuNe Forums (http://www.pprune.org/archive/index.php/t-460622.html)

Other comments on A320 cg changes, Google:
trim changes due to a320 fuel consumption

Conflicting quote: “It's interesting to note that the performance chapter for the A320 bases all the figures on a MAC of 33%. Seems to me that if you start off with a MAC of34%, the fuel burn will cause the MAC to decrease during the flight towards a lower number, say about 30% depending on the length of the flight. This will keep the MAC close to the book value of 33%. Since the performance figures are based on 33%, wouldn't it make sense to load the airplane to reflect this value? Seems not many ops people, chief pilots etc pay much attention to this area.” 20 May 2013 at:
A320 CofG THS [Archive] - PPRuNe Forums (http://www.pprune.org/archive/index.php/t-512584.html)

[Capn Bloggs]

Correct me if I'm wrong, but there are only two ways that the Airbus could have climbed as rapidly as it did: with severe and persistent up elevator or with CG way too aft
Actually, the amount of stick you need to generate that rate of climb isn't a lot: as a rule of thumb for my TCAS responses (passed on down by an old hand) I use: 1° of pitch change results in about your Mach number in Rate of Climb: If you're doing .8 and you pull 1° of pitch, your ROC will be around 800ft/min. I haven't actually used 10° on a TCAS RA :eek:, but lesser changes indicate those numbers are pretty close. It's not difficult (and certainly not severe) to pull 10°: there's your 8000ft/min climb rate... for a short time at least.

[oldoberon]

a lot of the discussions on the airbus fbw and just what is HAL capable of have questioned whether airbus actually do stall testing to garner data, does this post from way back throw any light on that

page 111 post2216

Quote:
Originally Posted by AM
The Concorde prototypes had a crew escape hatch
I'm not sure what your point is, but all the Airbus prototypes I've been on have had crew escape hatches. They would be used in case something went very badly during any of the many stall tests that were done

[.Scott]

Quoting Capn Bloggs
Actually, the amount of stick you need to generate that rate of climb isn't a lot: as a rule of thumb for my TCAS responses (passed on down by an old hand) I use: 1° of pitch change results in about your Mach number in Rate of Climb: If you're doing .8 and you pull 1° of pitch, your ROC will be around 800ft/min. I haven't actually used 10° on a TCAS RA :eek:, but lesser changes indicate those numbers are pretty close. It's not difficult (and certainly not severe) to pull 10°: there's your 8000ft/min climb rate... for a short time at least.You're measuring the stick movement by the effect of pitch on the plane - rather than the position of the control surface.

Having never flown anything heavy, my assumption is that to reach an 800FPM climb (FACs not-withstanding), you would pull back on the stick far enough so that your target ROC was reached in perhaps 5 or 10 seconds. Then you would relax the stick a bit to hold that ROC.

However, if the control surface (the elevator) jammed in place you would find yourself at 800FPM in say 7 seconds, 1600FPM in 15 seconds, 2400FPM in 24 seconds, and only a your airspeed would keep you from completing an inside loop.

If that rate of climb isn't enough to build up to what was seen in RADAR, then perhaps the pilot was merely trying to maintain altitude in a sudden down-draft. He may have been very aggressive in trying to restore altitude and attempted to cause that 1 degree pitch up in much less than 7 seconds.

The point is that a control surface movement applied for 5 seconds can be very normal - but when jammed in place for tens of seconds can be very severe.

Also, there is no deicing provided on the tail of the A320.

[skippybangkok]

On a swept wing, CG will always move back with fuel consumption if you deplete inside tanks first, which is preferential for wing loading

( assuming no other tanks, only wing tank )

[Volume]

When a tail loses lift the nose pitches down because the horizontal stabilizer pushes the tail down for stability.
...
Actually it is not for stability, but for moment compensation.
...
Actually it is for stability....modern jets are still aerodynamically stable..The Stabilizer is for stability (hence the name), but it does not necessarily have to "push down the tail" for that. Only the momentum arms around the center of gravity, the wing area and the lift over AoA curve slope define whether an aircraft is stable or not, this does not determine the direction of the stabilizer force. To word it very simplistic, an aircraft is stable if the wing loading of the forward wing is greater (taking into account the sign) than that of the aft wing. If the wing loading of the aft wing is negative, this is the trivial case. But it might be also slightly positive (the stabilizer lifts the tail) while still maintaining stability. All modern gliders produce lift on the tail for speeds lower than best glide. However, to compensate for the pitching moment of a cambered airfoil on the main wing, the stabilizer always has to move the nose up (i.e. a Canard has to produce lift, a conventional tail has to push the tail down)
The highest stabilizer downforce required for modern transport aircraft is to compensate the extreme pitching moment of the main wing with full flaps. In cruise, modern aircraft do not produce significant downforce, some even produce slight lift. However, due to complexity trim tanks do disappear again, and we are now moving a bit away again from the idea of the stabilizer producing lift, as the drag penalty of the stabilizer downforce is neglectable in transonic cruise.

[mm43]

... a Canard has to produce lift, a conventional tail has to push the tail down
Thank you Volume for reinforcing that very point; the THS of a modern airliner has a negative camber, a point that I believe has been lost in the preceding discussion.

[Ian W]

a lot of the discussions on the airbus fbw and just what is HAL capable of have questioned whether airbus actually do stall testing to garner data, does this post from way back throw any light on that

page 111 post2216

Quote:
Originally Posted by AM
The Concorde prototypes had a crew escape hatch
I'm not sure what your point is, but all the Airbus prototypes I've been on have had crew escape hatches. They would be used in case something went very badly during any of the many stall tests that were done

If that is the case it seems somewhat dilatory to not provide the aircraft stall and post stall behavior information to the simulator designers. The sim behavior would be then be correct; and we are repeatedly told that it is not as there is 'no data' to base the behavior on.

[ventus45]

post 3061 - RetiredF4
And if the full forward stick does not lead to the desired reaction, feed in manual trim.

What good would that do ? If "the system" wants 1g, if you trim the THS nose down, won't it just keep feeding in up elevator to counter you, until it is finally full up ? By that stage you will have far more THS nose down trim than is healthy. Might you then be in a worse place than from whence you came ?

[Australopithecus]

No. When you apply full forward stick you get full elevator travel, at least until the lower G limit of -1 is reached. If you manually move the trim wheel, automatic stabiliser trimming stops for a period of time. Hence, a little nose down stab trim can be a bad thing if the pilot then subconciously is relying on the FBW to complete the THS nose down travel.

In the very high AOA cases they claim there is no valid data set upon which to build a sim model. Yet Airbus used a sim to model the AF447 flight. From that experience they changed the stall recovery to include the selection of flaps one below FL210, the goal being to extend slats, thereby decreasing the net angle of attack. They also noted an improved stall recovery with manual stab trim, exactly as in almost every modern transport jet.

We used to go decades without hearing of a stall accident. Now it seems to be weeks. What gives?

[ventus45]

Post 3069 - Leightman 957


In the early 80's I believe NASA did some testing of deep stall characteristics using a single place T tail Schweitzer 1-36 which was modified to permit the horizontal stab to angle nose down to about 45 degrees. The pictures of tell tail streamers angled up about 45 degrees to the wing mean chord in a steady stable descent was arresting.http://www.mediafire.com/view/sdwzccjfxeqqm5j/Glider-deep-stall-nasa-03.jpg
http://www.mediafire.com/view/2sa52gkif2lj1sl/Capture5.PNG
http://www.mediafire.com/view/2t762l1386180o6/335051main_ECN-28129_full.jpg
http://www.mediafire.com/view/idkla5unbu169nv/335039main_ECN-26847_full.jpg
http://www.mediafire.com/view/d62mdhc4llmml16/335027main_ECN-26845_full.jpg
http://www.mediafire.com/view/fq487444o1z2fms/Glider-deep-stall-nasa-87982main_H-1242.pdf

[A-3TWENTY]

When the AF accident took place I went to the sim to reproduce the accident.

35000 ft ,ALTN LAW , pitch up , gained altitude , until stall.Once the airplane was completed stalled , with R/D nearly 10000ft/min , started recovering.

As per manual. Nothing . Tried a few times with and without power but with sidestick ALWAYS full forward. Result: crash.

There is only wat to get out of the stall.Keep the sidestick full forward and imediatelly manually pitch down the trim wheel.Very fast. And then you recover at about 20,25 thousand feet.

Furthermore:

Airbus blames it is impossible to stall the airplane in NORMAL LAW. IT isn`t. It is possible and it already happen without consequences.

[Sop_Monkey]

Did you throttle back, or bank the a/c 90 degs, or lower the gear etc., to try and get the nose down? If so and were unable to recover as you have written, the a/c should not have been certified in it's present state, IMHO.

Was the appropriate high altitude stall data programmed into the simulator?

[Capn Bloggs]

What good would that do ? If "the system" wants 1g, if you trim the THS nose down, won't it just keep feeding in up elevator to counter you, until it is finally full up ? By that stage you will have far more THS nose down trim than is healthy. Might you then be in a worse place than from whence you came ?
Are you for real? 40° AOA, full power, 10° nose up descending at 10,000ft/min all the while banking/turning and you think the FBW will be trying to give you 1g? In any case, a full nose down stab+full nose up elevator is bound to be better than the other combination when you're trying to get out of a stall if the silly FBW is opposing your full nose-down stick input...

[A-3TWENTY]

Was the appropriate high altitude stall data programmed into the simulator?

I don`t know if the sim really reproduces the airplane bahaviour. But it is supposed to do it.
Despite I think test pilots never took the airplane to such conditions in order to see it.

[Sop_Monkey]

Thanks for your input. I don't think they did either.

[RetiredF4]

post 3061 - RetiredF4
Quote:
And if the full forward stick does not lead to the desired reaction, feed in manual trim.

Quote Ventus
What good would that do ? If "the system" wants 1g, if you trim the THS nose down, won't it just keep feeding in up elevator to counter you, until it is finally full up ? By that stage you will have far more THS nose down trim than is healthy. Might you then be in a worse place than from whence you came ?
ventus45 is offline

The system wants, what is demanded by the SS position. Therfore the positioning of the SS to nose down is the first priority. If that works, than fine, but if it does not work fast enough, than the trim most probably is already all the way up.

If we look back to the documented stall accidents we know, that most crews were reluctant to do that in an appropriate way. The ND input was not present at all, was not far enough nose down, not long enough down or accompanied by noseup inputs averaging in an overall nose up input. This inapropriate SS handling may command a loadfactor value greater than the one present while descending in a stalled attitude. The consequence is that the flight computers may drive the elevators and in turn the THS trim to full nose up position.

As long as the elevators are nose up from neutral, the trim will not move afaik despite the SS nose down position. As the certification requirement is -1 and +2.5g, I assume that a full nose down SS input would not deliver more than 0 G (i could not find a reference with the applicable loadfactor demands in relation to the SS position). A controlled manual trim input would assist the SS input and not counter it.

In A320 series the THS trim might have stopped depending on the law reconfiguration, and it might only be available in mechanical mode.

But is there time for error and try?
As I said before, follow the procedure, which says under step 2.b
" Nose down pitch trim .......as needed.

[FDMII]

RetiredF4;http://www.pprune.org/rumours-news/553569-air-asia-indonesia-lost-contact-surabaya-singapore-155.html#post8855181As long as the elevators are nose up from neutral, the trim will not move afaik despite the SS nose down position. As the certification requirement is -1 and +2.5g, I assume that a full nose down SS input would not deliver more than 0 G (i could not find a reference with the applicable loadfactor demands in relation to the SS position). A controlled manual trim input would assist the SS input and not counter it. I concur. Experiments with the A330 sim, (understand the arguments re sim "duplication of stall" and "no-data", etc.), demonstrated that the THS followed SS position; full-ND SS brought a -13° THS setting (the result of an extended NU SS), to approximately -2°, recovering the stall in about 45" with a height loss of about 15,000ft. Manual rotation of the trim wheel forward could only help.

IIRC from the Perpignan accident report, the THS stops trimming with a stall warning. I would have to consult the report again to see if a comment or recommendation regarding the use of manually setting the THS would have provided conditions for recovery - they didn't have much altitude to start with...

[Machinbird]

On the flip side, I 'spect if one rolled in full nose down manual trim for recovery, one would have a tiger-by-the-tail when and if the stall broke at some 30 or so degrees nose low and accelerating with a limiting 2.5 g available.Yep, I agree. You would ideally like to dial in a 300 knot trim setting, and only if you absolutely needed it to break a stall would you go to a lower trim setting. But them you better have PNF primed to dial it back pronto as soon as the airspeed begins to accelerate past 200 knots.

Probably better to rock the aircraft out of the stall than to dial in those last few nose down units. More than likely, it would be a quicker and more positive recovery.

[Not registered]

Flaps extension below 20000 or speed brake is the only way to recover
Tested in the sim .. No other inputs will change the turbulent flow .. Perhaps trimming the THS but at 15000 fpm highly unlikely given the severity of emergency and unreliable speed compunded by adr aural warninge and messages . Switching off adr"s and extending the flaps below 20000 and speed brakes , trying to fly pitch n power or BUSS is the only way to recover

[fitliker]

Being in a stalled aircraft in turbulence is no fun ,Being in a stalled iced laden aircraft in turbulence in IMC is time to get the QRH prayer mats out.
If you are brave/dumb enough to go into a 50,000 foot CB you will probably be iced up as well and the aircraft deep stall recovery techniques practiced in the sim may not work .
It may need a combination of tail plane ice stall recovery techniques combined with gentle yaw and roll induced by gentle application of rudder to get the gravity working in the right direction to give you relative airflow without overloading the wing or control surfaces.
Keep in mind that any aircraft when it is iced up can be a wobbly thing to control ,and you may encounter some un-commanded pitch ,roll and yaw changes to the attitude that can be confusing .

[RetiredF4]

Quote:
On the flip side, I 'spect if one rolled in full nose down manual trim for recovery, one would have a tiger-by-the-tail when and if the stall broke at some 30 or so degrees nose low and accelerating with a limiting 2.5 g available.

Quote Machinbird
Yep, I agree. You would ideally like to dial in a 300 knot trim setting, and only if you absolutely needed it to break a stall would you go to a lower trim setting. But them you better have PNF primed to dial it back pronto as soon as the airspeed begins to accelerate past 200 knots.

Probably better to rock the aircraft out of the stall than to dial in those last few nose down units. More than likely, it would be a quicker and more positive recovery.

Rolling the trim to a normal cruise setting or take off setting initially would aid in the recovery and should cause no harm. The change of trim is not instantaneous and the elevators are still controlled by the Flight computers to achieve the loadfactor commanded by the SS. Hence when the AOA comes down to below stall value and the speed builds up, the trim is in the correct range. Imagine what would happen, if the trim would still be in full nose up position at the point of recovery? By increasing speed it gets more effective and kicks the aircraft back into a secondary stall.

MB, i know what you mean by rocking the aircraft out of stall, but i estimate the success rate of a comercial pilot in doing so very low. Same for extending something to change the airflow. Those are last ditch maneuvers with uncertain outcome. Using the rudder without the dampers active or in a degraded mode and no limiter working might brake off the tail.

In AF447 Bonin was occupied by the bank angle, while a healthy bank angle would have helped him to bring the nose down and get the speed back. Anytime the bank angle was greatest, the nose came down, and anytime he managed to level the wings the nose came up again.

The fast jet drivers in an out of control recovery (Spin is different) know not to deal with aileron or rudder inputs until the nose is below the horizon and the speed is building up, only then it is time to correct the attitude by rolling to the nearest horizon. In a comercial aircraft it might be necessary to control the bank angle within a given limit like 45° or 60°, but i see no point to level the wings as long as the aircraft is still in high AOA. The High AOA is not a bank angle problem, it is a pitch against flight path problem. That is a point where the new stall recovery procedure is not clear about at least not to my sense of thinking.

If all that normal procedural stuff does not work, then it might be the time to go into test pilots territory and try something outside of the procedure.

[Capn Bloggs]

I 'spect if one rolled in full nose down manual trim for recovery, one would have a tiger-by-the-tail when and if the stall broke at some 30 or so degrees nose low and accelerating with a limiting 2.5 g available.

I don't think so. 30° nose down pulling at not even 2g starting at say 150KIAS with no power would probably result in another stall, not a wing-ripping-off mega overspeed... The drag at 200KIAS pulling the equivalent of a 60° bank turn is going to require a fair bit of power. You will obviously have to trim back but it wouldn't be a problem in my view.

[Sop_Monkey]

We still have the speed/air brakes on this type of aircraft do we not? Or is it a case the computer inhibits the A/B to reduce speed because it's automatic for landing only??

[xcitation]

And Mmo testing.
It's not clear to me that anything less than ejector seats would be an reliable means of escape, particularly if the pilots/engineers were experiencing +/- a couple of g.
I have seen 'Bus test pilots claim that the orange suits and parachutes were mostly a box-ticking exercise.

With a hatch forward of the engines there is a risk of the test pilot causing foreign object damage to the engines! Or would you wait for them to spool down :ouch:

[A0283]

Basarnas has just announced that one of the pilots has been recovered. The pilot was still strapped in his seat. The seat was close to the cockpit. And the cockpit apparently only 20 m (instead of first reported 500 m) from the main fuselage. It is not clear if its the captain or his F/O.

NTSC already reported earlier that the captain was seated on the left and the F/O on the right.

[Stabilo31]

Most probable scenario is :

Captain resetting the FAC's =

Loss of the A/P

Red "SPD LIMIT" appeared on both PFD's speed scale

F/O get confused and tought "SDP LIMIT" is an overspeed warning and thus

pulled up sharply... stalled...

[Sop_Monkey]

In other words, lack of appropriate training.

[Leightman 957]

Uncle Fred: Even having been exposed to some of this training in the sim, I did not really take to heart what it would be like to have to push over that much at 350 and how I would have to be fighting what the body would be telling me not to do.

I know that there are a LOT of posts as far (agreement is probably going too far) to the effect that pushing forward, or anything less than 1.00 positive G is uncomfortable, unfamiliar, non-intuitive, and frowned on by management. But it seems pretty clear that poster opinion agrees that there are circumstances when this action is appropriate and even immediately mandatory. I am excluding airframe G limits and myriad possible computer interactions for the moment because they mislead away from the fact that lack of comfort or familiarity is not an excuse for not doing the right thing. If one never ever practices something but thinks that carrying it around in their head as an intellectual trivia bit for use in extreme situations will be sufficient come the need, the success rate is going to be low. And while evident on the FDR might be plain, they why probably will not at all be apparent on the CVR.

I can't help recalling that WWII German pilots got themselves out of a lot of nasty spots by pushing over. Written about later the reason given was always German fuel injection capability over American carburetor incapability. But it wasn't mentioned that pushing also offered the benefit of being counter-intuitive.

I've spent enough time hanging from a seat harness to know that in addition to the brain drain resulting from all the mixed up kinesthetic sensations, control touch inverted or even in positive sub 1 G can be a much different animal depending on one's personal fright curve. And I have to say that the idea that there are a lot of airline pilots out there with no clue whatever about those differences is alarming if not frightening. Granted it may never be needed, but the idea that a pilot would not only be uncomfortable but also would have no interest in pursuing those aspects of flight outside the norm is not preparedness norm I have always expected of pilots who got farther along than I did. Intellectual knowledge does not equal knowledge plus kinesthetic preparedness. What one is not willing to explore out of cautious self preservation will eventually come as a pop quiz in less than propitious circumstances.

[Sop_Monkey]

On the 320/330 aircraft, are the inboard and outboard spoilers able to be deployed independently?

I ask this as "splitting the spoilers" is an excellent solution to pitch problems on some swept wing aircraft I have operated. For example a jammed stabilizer. To lower the nose, outboard spoilers can be inhibited and the required amount of inboard spoiler can be applied for the required results.

This maybe a possible solution to getting the AoA reduced in a stalled condition if all else fails and as a last resort.

[Uncle Fred]

Leightman,

Perhaps you might have misunderstood my post or else (probably the case) I did not write clearly enough. I would most definitely push over into negative g territory if needed to recover the aircraft. What I was alluding to is that RetiredF4 brought forth some food for thought in that even if we have done UAS training in the sim, that it is worthwhile to ponder and fix in our mind that what we have to do is something that we might not have done for years.

Many of us on these threads have been lucky enough to have flown aircraft that will gladly enter this territory and therefore are familiar with the sensations. I count myself among those lucky as do you. I will also admit however, that it has been a number of years (decades now?) since I have done so. Should I be faced with the prospect of a UAS at FL350 with rapidly decreasing airspeed I will do what is necessary to try to recover. I just need to remind myself, as did another poster, that doing so at night, at high altitude, in bad weather/IMC, is going to take very deliberate and conscious effort--including actions that might feel to be a bit outside the comfort zone. F4 was talking about pilots in fighter lead in (probably flying BFM) in what I assume to be day VMC. Even then he notes that they were reluctant to push too much. What does that say about the rest of us?

I would hope that none of us would sit there and watch a bad situation deteriorate even further but recent history is proving me wrong on that count. Training is of course the key but what I was drawing from F4's remarks was that even then it is going to be a lot different than it is in the sim.

[Leightman 957]

Thanks for the clarification UF, but I think I understood what you meant. It may well have been me who was unclear. I have less concern about older pilots who came up through the ranks flying more kinds of AC than with the descriptions posted elsewhere here about the more recent crop of fast tracked new kids who took a different, more 'streamlined', and much less varied route working from small to heavy aircraft. Pilots I've known flew for fun on their time off, often in rag and stick or a wide range of other contraptions, some of which had almost no knobs. I think their curiosity made them better pilots. In any event I'd rather have one of them up front.

[Radix]

Why not program in an automated stall recovery
Now this is interesting. The consensus in this thread so far is that pilots have become too dependent on automation.

If pilots have become too dependent on automation, the solution is to add more automation? All that does is exacerbate the problem. It's a vicious circle.

[Naali]

Radix,not all the pilotage is here. Most would like to keep it as simple as possible,-but sure,have the benefits the automation can bring about. Humanly logical automation might be the words we are after.

[Ian W]

Now this is interesting. The consensus in this thread so far is that pilots have become too dependent on automation.

If pilots have become too dependent on automation, the solution is to add more automation? All that does is exacerbate the problem. It's a vicious circle.

Perhaps all that is needed is not so much an automated stall recovery so much as automatics sensing approach to stall and stall not making things worse. For example as the aircraft approaches stall the THS could stop trimming nose up, if the pilot wants more nose up then he can manually dial it in. Perhaps _at_ the stall, and you can get there in Normal law if you zoom climb into it at high cruising levels, the THS could motor to neutral; again the pilot could stop it manually if necessary. Had the THS motored to neutral in the AFR447 case the aircraft would probably have pitched nose down and might have been recovered.

[rideforever]

It would be good if pilots could easily download sim scenarios for these newsworthy incidents, and work through them.

[mcloaked]

AirAsia flight QZ8501: Bodies of two pilots found in cockpit, one retrieved - South-east Asia News & Top Stories - The Straits Times (http://www.straitstimes.com/news/asia/south-east-asia/story/airasia-flight-qz8501-bodies-two-pilots-found-cockpit-one-retrieved-)

[Bleve]

I know that there are a LOT of posts as far (agreement is probably going too far) to the effect that pushing forward, or anything less than 1.00 positive G is uncomfortable, unfamiliar, non-intuitive, and frowned on by management. But it seems pretty clear that poster opinion agrees that there are circumstances when this action is appropriate and even immediately mandatory.Aerodynamics 101: The stall speed at 0 'g' is 0 kts. Therefore if you have the elevator authority to push to zero 'g' you will unstall the wing at any airspeed. The nose will drop, the airspeed will increase and when comfortably above Vs1g, gently roll wings level and raise the nose to the horizon. If you don't have elevator authority to push forward enough to unstall the wing, ROLL the aircraft (90°+ bank if need be) and convert that pitching 'up' moment away from the horizon into a pitching 'up' moment across (or down from) the horizon to get the nose to drop and airspeed to increase.

[Petrolhead]

Yes Bleve, the concept of zero stall speed at zero "g" does not seem to be instinctive to pilots that have never worked beyond 30 degrees of bank. If I may add to your post -

"If you do not have elevator authority to push forward enough to unstall the wing - get that authority by trimming forward and reducing thrust if needed".

If the nose does not do as you command it in a 320, the trim is yours!

[NigelOnDraft]

Perhaps all that is needed is... automatics sensing approach to stall .... as the aircraft approaches stall the THS could stop trimming nose upYou mean like the A320 does?

[FDMII]

@IanW; #3109, http://www.pprune.org/rumours-news/553569-air-asia-indonesia-lost-contact-surabaya-singapore-156.html#post8857067, "Had the THS motored to neutral in the AFR447 case the aircraft would probably have pitched nose down and might have been recovered. " Point-of-information: - the THS would have motored from -13.5° to about -2° had the stick been held fully-forward for a sufficiently long period and very likely the aircraft could have been recovered. Also, manually rotating the trim wheel disengages the autotrim permitting a quicker setting of the THS. When released from manual movement in a few seconds it returns to auto and begins to take into account control inputs, but by that time recovery actions are theoretically taking place and the THS would follow-up with the SS orders.

[Ian W]

You mean like the A320 does?



Exactly Nigel,:ok: but perhaps you should continue with the quote. When it _is_ stalled the A320 just keeps the THS where it got to, if it motored to neutral it could help a lot. Unless you can think of a reason after the stall why the THS should stay nose up at all.

[TheInquisitor]

anything less than 1.00 positive G is uncomfortable, unfamiliar, non-intuitive, and frowned on by management.

I guarantee that meeting the surface of an ocean @10,000fpm is even more uncomfortable...

If the nose does not do as you command it in a 320, the trim is yours!

Every part of an aircraft should ALWAYS do as its commander commands it - else he does not '...have final authority as to the disposition of the aircraft...' as required by the Chicago Convention.

How on earth did we end up designing and accepting aircraft that the pilot cannot COMPLETELY override if necessary, and automation that confuses, confounds, and when the fecal hits the turbine, leaves you to recover from an unusual and precarious situation requiring counter-intuitive actions?

[NigelOnDraft]

When it _is_ stalled the A320 just keeps the THS where it got to, if it motored to neutral it could help a lot. Unless you can think of a reason after the stall why the THS should stay nose up at allHow do you definitively define "it is stalled"? To a high enough degree of integrity you can remove pitch control from the pilot?

[Sop_Monkey]

Inquisitor

Spot on:ok:

The aircraft i've operated, and there has been quite a number, If all else failed I could be pretty sure of having a set of primary controls to manipulate to the desired effect. This now seems to be no longer the case.

Indeed how was it ever certified in it's present state??

[Machinbird]

Quote:
Perhaps all that is needed is... automatics sensing approach to stall .... as the aircraft approaches stall the THS could stop trimming nose up
You mean like the A320 does?NOD-only true for the 99.999% of the time you are in Normal Law. In Alternate law-Not true. During an upset, you are very likely to end up in Alternate law.

One thing that will interfere with achieving the necessary near 0 g in a nose high upset (which must be maintained until the aircraft is actually nose low and flying again) is an excessively trimmed THS.
(There is a good possibility that the THS trim was a factor in the Air Algerie failure to recover from its stall and roll off.)


P.S. I know you know the A320 systems very well.:)

[toffeez]

"The aircraft i've operated, and there has been quite a number ..."

Evidently not an Airbus, seeing your questions about A320 spoilers, which no-one bothered to answer (because G;ggle would have clarified all in 5 min).

How was it ever certified? Because the FAA certified it, that's why. You think jet transports should still be designed with wires pulling the control surfaces?

[auraflyer]

When it _is_ stalled the A320 just keeps the THS where it got to, if it motored to neutral it could help a lot. Unless you can think of a reason after the stall why the THS should stay nose up at all
How do you definitively define "it is stalled"? To a high enough degree of integrity you can remove pitch control from the pilot?

When the stall warning sounds?

i.e., if the stall warning goes off, THS must automatically roll forward to at least neutral asap (or go nose-down if you -- controversially -- want to simulate a stick-pusher)

Of course, this should be something not needed to be left to automation

[NigelOnDraft]

When the stall warning sounds?

i.e., if the stall warning goes off, THS must automatically roll forward to at least neutral asap (or go nose-down if you -- controversially -- want to simulate a stick-pusher) So if as I rotate on takeoff, the Stall warner erroneously sounds, the THS drives the aircraft into the ground :{

PS ...to at least neutral What is "neutral" in airliner terms?

[CONF iture]

How do you definitively define "it is stalled"? To a high enough degree of integrity you can remove pitch control from the pilot?
How do you suddenly bother about that ... ?
How do Airbus definitively define "it is going to stall" ? To a high enough degree of integrity Airbus can remove pitch control from the pilot ?

[auraflyer]

So if as I rotate on takeoff, the Stall warner erroneously sounds, the THS drives the aircraft into the ground

I was just putting the logical result of Ian W's suggestion into words as it is an interesting idea and I try to keep an open mind -- but I don't think the solution is more automation, hence why I put "controversially" and why I ended how I did.

I won't get into a fight, since you drive A320s and I don't, but AFAIK existing stick pusher logic includes an altitude minimum (e.g. Q400 only activates > 200 feet AGL), so there's no reason you would not implement equivalent logic *if* you were to do this.

[zzuf]

A stick pusher is a stall identifier, it is not a stall warning.
They are two different systems.

[ekw]

So lets say 2 in every 10 pilots are aces, 3 are average and 5 are dunces. Which group does automation help and which group would be less affected by more automation? The logic is simple surely?

[ASRAAM]

For those suggesting Stick pushers, or a mechanism to set a neutral tail plane at the stall consider this: To have arrived at that situation in the first place a failure has occurred, quite probably with one of the systems that would have been providing the information that the recovery system would be using!

In order for a recovery system to have any validity it would need aircraft data from a COMPLETELY independent source, actually SEVERAL independent sources.

Now, if you are going to do that why not just take those sources and use them to supply data to the original fly by wire so you don't stall in the first place.

[rideforever]

Isn't the real story here that airlines / manufacturers want to fully automate flight. Pilots and crew are seen as expensive.

And so Airbus has tried to start that process. It couldn't go all the way fully-automated because there would be huge resistance from passengers / crew / regulators, but it has implemented a beginning.

The Airbus system comes with a manual of how to use it, makes it sound so easy ... however if something goes wrong it is unclear how to resolve the situation because the system's many secrets are not made available and in an emergency you have seconds to understand what's going on under the hood.

Airbus does not want pilots to be able to switch the system off at will, because that would derail the business plan of full automation.

For the bean counters, it's just money. Lives lost though regrettable are just a matter of insurance.

Automation seems the trajectory of the economy ... unless something changes. And we are now in an intermediate phase were there is an inevitable dishonesty about what is occurring, because automation is being phased in semi-covertly.

If the pilots / crew make a fuss, or passengers / airlines are scared ... then it will slow things down. If new plane technologies come through that require pilots, it will slow things down. If pilots were seen once again as part of the experience, it will slow things down. If the world gets richer suddenly it will slow things down.

[Ian W]

I was just putting the logical result of Ian W's suggestion into words as it is an interesting idea and I try to keep an open mind -- but I don't think the solution is more automation, hence why I put "controversially" and why I ended how I did.

I won't get into a fight, since you drive A320s and I don't, but AFAIK existing stick pusher logic includes an altitude minimum (e.g. Q400 only activates > 200 feet AGL), so there's no reason you would not implement equivalent logic *if* you were to do this.

I am glad to see that my suggestion triggered some discussion. If I were looking to design something along those lines I would expect to use AOA and probably a variable delay dependent on flight phase. A parameterized delay would prevent spurious warnings triggering trim changes. Although I note from other events that spurious warnings seem to trigger zoom climb in alternate law.

[The Banjo]

Stick pushers bla bla bla

The big picture is these complex machines are designed to be operated by appropriately recruited, educated, trained, current and competent crews who adhere to SOP's, FCOM, Air Nav regs etc etc etc

No amount of anything will safe guard the aircraft and innocent passengers from alleged utter stupidity.:ugh:

[henry_crun]

Not a pilot, just an avionics guy, so tell me to go away if you wish.

I would suggest the use of totally separate, lane segregated, battery powered gps at the four corners of the airplane. Collectively they could report a dangerous rate of descent. Differentially they could detect inappropriate attitudes.

Gps accuracy is not good in airplane control terms, but it is definitely accurate enough to sense outrageous errors.

Why not?

[Gysbreght]

Collectively they could report a dangerous rate of descent. Differentially they could detect inappropriate attitudes.More often than not the stall results from an inappropriate rate of climb, and the attitudes can be quite normal.

[TheInquisitor]

Isn't the real story here that airlines / manufacturers want to fully automate flight. Pilots and crew are seen as expensive.

And so Airbus has tried to start that process. It couldn't go all the way fully-automated because there would be huge resistance from passengers / crew / regulators, but it has implemented a beginning.

The Airbus system comes with a manual of how to use it, makes it sound so easy ... however if something goes wrong it is unclear how to resolve the situation because the system's many secrets are not made available and in an emergency you have seconds to understand what's going on under the hood.

Airbus does not want pilots to be able to switch the system off at will, because that would derail the business plan of full automation.

For the bean counters, it's just money. Lives lost though regrettable are just a matter of insurance.

Automation seems the trajectory of the economy ... unless something changes. And we are now in an intermediate phase were there is an inevitable dishonesty about what is occurring, because automation is being phased in semi-covertly.

If the pilots / crew make a fuss, or passengers / airlines are scared ... then it will slow things down. If new plane technologies come through that require pilots, it will slow things down. If pilots were seen once again as part of the experience, it will slow things down. If the world gets richer suddenly it will slow things down.

Some operators have expressed an interest in 'full automation' - but only because they have absolutely no appreciation of the end-to-end costs involved.

If they think pilots are expensive, wait till they see what a theoretical 'unmanned' airliner would cost to design, build, certify and operate.

Not only that, achieving the required level of safety for a passenger-carrying operation simply isn't technically feasible - and won't be in any of our lifetimes - if at all.

[HarryMann]

... in conversation with Leightman 957 it occurred to me (& maybe L957 too) that
stalling in general and higher altitude stalls particularly have been given much less
attention than those at low (more immediately threatening) altitude by safety authorities
and in liine training ?
... over a significant span of recent airliner development.

[TheInquisitor]

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.

[NigelOnDraft]

Isn't the real story here that airlines / manufacturers want to fully automate flightAnd plenty of posters on here seem to agree e.g. adding technology to solve every problem?

The Airbus system comes with a manual of how to use it, makes it sound so easy ... however if something goes wrong it is unclear how to resolve the situation because the system's many secrets are not made available and in an emergency you have seconds to understand what's going on under the hoodI 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.

Automation seems the trajectory of the economy ... unless something changes. And we are now in an intermediate phase were there is an inevitable dishonesty about what is occurring, because automation is being phased in semi-covertly.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.

[cribbagepeg]

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

[Mr Optimistic]

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?

[HarryMann]

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.

[TheInquisitor]

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.

[HarryMann]

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,

[TheInquisitor]

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.

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

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?

[PJ2]

TheInquistor;
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? 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.

[xcitation]

@Henry crun
Not a pilot, just an avionics guy, so tell me to go away if you wish.

I would suggest the use of totally separate, lane segregated, battery powered gps at the four corners of the airplane. Collectively they could report a dangerous rate of descent. Differentially they could detect inappropriate attitudes.

Gps accuracy is not good in airplane control terms, but it is definitely accurate enough to sense outrageous errors.

Why not?
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.

[ventus45]

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.

[silverstrata]

Banjo

Stick pushers bla bla bla

The big picture is these complex machines are designed to be operated by appropriately recruited, educated, trained, current and competent crews




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.

[Derfred]

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 l@ser gyros already pump out all the spatial data you could ever need, with all rates included.

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.

[ASRAAM]

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.

[Mahatma Kote]

In fact GPS is amazingly accurate when used diferentially to calculate attitude down to sub mm accuracy

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.

[NigelOnDraft]

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. 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?

[AR1]

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?

[skyhighfallguy]

<<<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!

[aterpster]

skyhigh:

BUT a pilot who takes his plane to MAA (max authorized altitude) and can't hand fly it there is fooling himself!

Can you elaborate a bit on that one?

[skyhighfallguy]

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.

[bubbers44]

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.

[captplaystation]

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

[Carbon Brakes 300]

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:

[Leightman 957]

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.

[Heathrow Harry]

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

[c.j.shrimpton]

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.

[Ian W]

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

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

[IcePack]

fatigued, frightened and inexperienced)
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.

[caulfield]

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.

[formulaben]

...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.

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

[wes_wall]

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.

[silverstrata]

Asraam

Exactly HOW does your stick pusher know it is approaching the stall, perhaps it will use the AOA probes ... that generated the reversionary mode in the first place.



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.

[Smilin_Ed]

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?

[formulaben]

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.

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.

[xcitation]

What Law Are We In?

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.

[Lonewolf_50]

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. This fits into the current legal environment nicely. That is what has a lot of management concerned: liability. 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. 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 ... )
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 load sheet, 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. ISO 9000 has arrived on the Flight Deck.

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

[A0283]

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.

[Oakape]

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!

[Nimbus4]

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


Flight Control Laws | Alternate Law - Description (http://www.efbdesktop.com/flight-controls/sys-7.3.1.html)

[Naali]

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

[scard08]

Can any Airbus guys say how often they have to fly in Alternate Law? Is it a regular occurence or something you just experience in training?

[ATC Watcher]

Superb post Caulfield, totally agree .
Same in our Profession, the most important part of Safety management today is satisfying audits and regulators questionnaires. If all the boxes are ticked, management opens the Champagne bottles and congratulate themselves how good they are.
But unfortunately I do not think "Good airmanship" " is one of the boxes.

[NigelOnDraft]

Can any Airbus guys say how often they have to fly in Alternate Law? Is it a regular occurence or something you just experience in training? 6K+hrs A340/320 - never.

Very rare on the line, of course practiced in the Sim.

if cruising at max altitude and you receive a tcas alert to "climb", don't do anything; the other aircraft will get tcas alerts to descend at a higher rateI trust your advice not to climb is not serious :{ How do you know the other aircraft even has TCAS? If you are Max Alt, and TCAS says climb, then FOLLOW IT :ugh:

[Trackdiamond]

Well posted old boy! We need more retrospecive thinking in this industry to correct matters.Its not just about speedy i-pad googly minds in the cockpit.We need Airmen who can THINK and DECIDE like AVIATORS.That means a liberal latitude rather than robotic SOP and punching buttons like a Digital DJ. Unfortunately when "Airmanship" criterion appears I the tick box..it is judged not objectively but more subjective assessment o how the TRE sees your operation dominated by CRM mandates.There is also the worrying trend that modern trained young pilots just because have CRM lessons in their syllabus seem to think they have a monopoly of expertise in the field and their misinterpretation of Assertiveness versus Aggressiveness might lead to undermining the authority of the Pilot In Charge.The AF Airbus 340 landing accident at Toronto amongst others bring to mind.Experience vs knowledge...two similar but quite different positions in the cockpit.At the end of the day when in dire straits..it is correct judgement that will count.And that comes on naturally..with years of hard earned experience.

[HeavyMetallist]

..it is correct judgement that will count.And that comes on naturally..with years of hard earned experience.
I've been quite surprised to see a number of posts along these lines recently, basically criticising CRM for empowering whipper-snappers to challenge wise old greybeards. I thought that Tenerife (and numerous accidents before and since) had demonstrated that "years of hard earned experience" do not necessarily equate to correct judgement in any given situation, and that a far greater risk is the FO cowered into silence by the higher status of their more experienced captain? It might be irritating to have your judgement regularly queried by a relative novice, but haven't we all (in whatever field) had the experience at one time or another of being challenged and thinking "damn, the kid's right"?

[Ian W]

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.

At one stage in my 'career' I qualified as an ISO-9000 auditor. One of the things that was expressed to me during the training was that procedures were not required for everything, only where it was really essential the procedures were not varied. Or to put it another way one of the more experienced QA instructors said:

"You go to audit some companies and they have several tables all covered with procedure manuals 2 or 3 deep. You go into others and they hand you a single slim folder. You know immediately which company actually follows their procedures."

I think that this has application in the aviation world. Less by rote procedures and more capable personnel will make a better more professional airline which in the long term will be safer and more profitable.

Unfortunately, that message has not percolated through to 'management' and tickboxes and inhibition of original thought are seen as the way to do it. That inevitably leads to the:

'if there isn't a procedure for it - you are not allowed to do it'; and,

'I have learned all the procedures in the manual and the boxes have all been ticked, so I don't need to know anything else.'

[A0283]

What I would like to understand is the huge difference between how the AirAsia and the latest TransAsia accidents are treated by the respective national authorities (both acting under ICAO Rules).

In the AirAsia case the (investigation) authorities have published few preliminary facts (radar, FDR and CVR data). But have published some short ‘final opinion’ conclusions( {we know what happened} “ we have the ‘key‘ “ – and – “it was not a suicide”).
In the TransAsia case the (investigation) authorities have already published many preliminary facts (radar, FDR and CVR data). And have published a ‘preliminary factual’ conclusion (one engine out and the second good one shut down too).

From a professional personal point of view you learn much much more from getting the preliminary facts yourself, struggle with them to find probable cause and contributing factors, and then compare these when preliminary, interim and final reports are published. The main learning moments being where the professional official report either confirms or rejects your professional personal conclusions.

From that professional viewpoint you can only be very very happy with the approach taken by the Taiwanese ASC. And at the same time negatively surprised by the approach taken by the Indonesian KNKT/NTSC.

In context, the Taiwanese ‘political’ risks appeared to be much greater than the Indonesian ones. Declaring the pilot a hero ( while keeping the ‘from hero to villain pilot’ case after rolling the 747 in mind ). Possibly shutting down the good engine too (keeping the UK 737 case in mind). And the mainland Chinese passengers (keeping general politics and MH370 emotions in mind).
In the Indonesian case no-one, not a single mention on Pprune I think, suggested a suicide. And no-one expects an investigation team to have the ‘key’ in an early stage. There is a lot of information that can be published without having any political overtones. Publishing the MH370 take-off fuel weight for instance would also have harmed no one, on the contrary one could even say.

Is there a Pprune member who has an informed opinion on this. And can give us a better understanding of how the Indonesian investigation might view its own QZ8501 approach.

[Lonewolf_50]

Ian:
As with any quality and standards system, the "spirit of the law" versus "the letter of the law" application remains problematic.

Your points are well taken, but that doesn't mean that the concept behind the system is reflected in practice.
(See also with various misadventures in Lean ... :mad: )

There is no substitute for knowing the aircraft thoroughly and knowing the limitations / constraints of the regulatory system (be it national or international) that is put in place with the intention of establishing some order to air travel and transport.

[Leightman 957]

RE IanW's stack of manuals: I attended a local emergency planning meeting, with fire department, and city, county, and state officialdom. The city manual was 50 pages long. The mayor and I were the only ones who had read it. The manual was all about who is in charge.

I have a very pedestrian 13 ton truck, one you see hundreds of on the road. It won't start. The local motor guru who can in 35 seconds diagnose 95% of all problems of pre-1985 light duty vehicles, plus HIS diesel guru still don't know whats going on after a week and, like a more monetarily restrained version of the truck dealer, have begun throwing dollars at it in hopes something will work. Someone somewhere knows all the troubleshooting SOPs. They don't live here.

I've used simple examples here because complex examples too often become a pack of dogs chasing their tails. If there are no ongoing, systemically encouraged conversations between those who have great knowledge and those who have great experience what you get in the group mind is advancing Alzheimers, in other words, increased relational complexity. Every pilot knows (or should) that all you need to guarantee an accident is too many complexities in too short a time. Eliminating complexities is automation's promise. But the issue here is when automation increases complexity. There aren't any pilots, no matter their training, knowledge, or experience, who are not vulnerable to overwhelm. Some of the arguments that more training would solve everything seem be made by people who haven't yet had the whee squeezed out of them and now know beyond a shadow of a doubt they were saved only because of luck. I have, so I know I don't know everything. That makes me skeptical of arguments like "If you knew what I know", and "If you knew more", unless I know for a fact that that the person had a whee squeezing event where serendipitous luck and not his own abilities clearly saved his bacon.

[c.j.shrimpton]

Leightman.
As one of those who advocates more stall training in the sim, I think I should reply. The point I was making was that the recovery from a fully developed stall, especially at very high altitude is quite the opposite of what is taught to airline crews, with monotonous regularity, for the avoidance of an impending stall at low level. The crew must be able to recognise when stall prevention gives way to stall recovery and this has to be instinctive and mustn't be delayed. If necessary the recovery attitude (and power) needs to be applied for a protracted period of time and with a large loss of altitude. The resulting trajectory has to be accepted even if it takes the aircraft into a CB or terrain. Until the aircraft is unstalled and flying again, nothing else matters. Just hope you've got enough airspace.
When I read details of the various reports of aircraft upsets, I always wonder if I could have coped as well as the guys who survived or any better than those who didn't.
Yes, I've also had many lucky escapes.

[PJ2]

A very fine post, Leightman 957.

[1953Buick]

Ian, I don't believe that ISO quality and management systems are really too applicable to pilots, perhaps more to aircraft maintenance, etc.

Normally ISO systems work well, such as in factories, where it is important that the employees do exactly what their job is every time. Of course, there are many ways within that system that employees can initiate changes and improvements to their particular processes, but only after review that is not instantaneous. But day in, day out, what works best is that they do what is written in their SOP's for that job.

However, seems to this non-pilot that while pilots have to have guidelines, checklists, etc., their qualifications and training has to be at a high enough level that they can handle the emergencies that can arise and may not be covered in a manual or a procedure.

[IGh]

Question posed:
Investigative approach ... KNKT/NTSC ?
Air Asia Indonesia Lost Contact from Surabaya to Singapore (http://www.pprune.org/rumours-news/553569-air-asia-indonesia-lost-contact-surabaya-singapore-160.html#post8861201)
at slot #3182 (http://www.pprune.org/8861201-post3182.html) (permalink (http://www.pprune.org/rumours-news/553569-air-asia-indonesia-lost-contact-surabaya-singapore-160.html#post8861201)), dated 10Feb

See discussion in http://www.pprune.org/safety-crm-qa-emergency-response-planning/489479-bias-independent-investigating-authority.html#post8861604

[fireflybob]

I've been quite surprised to see a number of posts along these lines recently, basically criticising CRM for empowering whipper-snappers to challenge wise old greybeards. I thought that Tenerife (and numerous accidents before and since) had demonstrated that "years of hard earned experience" do not necessarily equate to correct judgement in any given situation, and that a far greater risk is the FO cowered into silence by the higher status of their more experienced captain? It might be irritating to have your judgement regularly queried by a relative novice, but haven't we all (in whatever field) had the experience at one time or another of being challenged and thinking "damn, the kid's right"?

Heavymetallist, I think you are conflating the issues here. I don't think we are talking about good CRM etc.

The issue is that new pilots (through no fault of their own - they have been trained that way) are good at complying with SOPS etc but lack the hands on skills which given the current level of automation can leave them lacking when things don't go according to plan.

The fact is that oldies that have done lots of flying on older generation types are "hard wired" neurologically for manual flying (they may be a bit rusty but they can confidently hand fly). New pilots do not have those skills to fall back on.

[Machinbird]

What I would like to understand is the huge difference between how the AirAsia and the latest TransAsia accidents are treated by the respective national authorities (both acting under ICAO Rules). Maybe the Indonesian KNKT/NTSC is scratching their heads still over how the wobbly flight path initially observed relates to the later loss of control in the vertical direction.:hmm:

[captplaystation]

They are certainly taking a while to go from the initial ( & probably ill-advised) revelations, to coming up with some tentative explanation of WTHIH (old readers of Flight International will know that one. . .What the Hell is happening )

Perhaps they too, are slightly "unclear" of what/how/why an Airbus performs its "Magic" . . . . . .

[xcitation]

FireFlyBob
The fact is that oldies that have done lots of flying on older generation types are "hard wired" neurologically for manual flying (they may be a bit rusty but they can confidently hand fly). New pilots do not have those skills to fall back on.

How do you define "oldies"?
Apparently 20'000 hours did not help in this incident:

AirAsia

Captain (53)
Air Force veteran, was very experienced, with around 20,000 flying hours under his belt including 6,000 on AirAsia's A320.

FO (46)
2,000+ hours with the carrier.

AF447
Captain (58)
Experience:
total: 10,988 flying hours, of which 6,258 as Captain
hours on type: 1,747 all as Captain

FO1
total: 6,547 flying hours
on type: 4,479 flying hours

FO2
total: 2,936 flying hours
on type: 807 flying hours
Glider pilot

[fireflybob]

How do you define "oldies"?
Apparently 20'000 hours did not help in this incident:


xcitation, I didn't say oldies were infallible.

In the case of AF447 the Commander was not on the flight deck and/or at the controls when the event started to materialise.

In the case of AirAsia it would be interesting to know how much of that 20,000 hours was done on large jet transports with round dials, basic autopilot with no auto throttle and no FMC etc.

Perhaps "oldies" was an inappropriate term to use but the point I am making is that those who have done a lot of hand flying basic jets with minimal automation (even if a bit out of practice) are in a better position to maintain safe control when the automation decides to be not available.

Years ago we would think nothing about despatching with an inoperative autopilot because we knew we could competently hand fly at cruise levels.

[Sop_Monkey]

fireflybob

"Years ago we would think nothing about despatching with an inoperative autopilot because we knew we could competently hand fly at cruise levels."

Exactly! Character building stuff and it kept us awake. Well most of us anyway, in remote areas. South Atlantic comes to mind. Pre RVSM of course.

If you can hand fly at cruise accurately, you can normally do what you needed to do with the a/c hand flying. Got quite good on raw information too as the FD wasn't all that helpful in pitch at cruise altitude, IIRC.

[skyhighfallguy]

I would like to know if anyone has ever had a checkride in a sim (or plane) that involved 5 minutes of straight and level hand flying at MAA or service ceiling?

[Vilters]

I am a pilot.
Flew light to medium, even have a BFM (Basic Fighter Man) hr in an F-16B, and yes we pulled the whole 9G's a couple of times.

No, all those "Thousands of hrs" airline pilots do not need a single extra hr in a simm. NOT a single hr.

They need "REAL" seat time in a Cessna 152, a Pitts, or a Cap10.

They "need" some "REAL" and "DIE HARD" stalls to cope with, not in any simm at all, but in real life.

Where their bottoms come loose from the seat.
Where the break drops the nose deep and the wings fall ways from you.

I'v had "real" pilots turn white as paper.

I'v had guys shouting and screaming; sweating and strugling.

All they ever did was; "Stay away, stay away, recover before the stall."

Well, I fear the results speak for themselves.

And then do a full deep stall in a twin.
And teach them to cartwheel out of the stall. Full rudder and Full power on one, chop the power on the second, and cartwheel overhead out of the stall.

Then you will have pilots that start to understand stalls.

You might see some pilots turned WHITE, but you"ll have better pilots.

You can put them in a simm for weeks, nothing will ever change.

[Sop_Monkey]

You all may want to have a look at this. It ain't pretty to watch but this is what can happen. Look and let's learn. Borrowed from another thread.

https://www.youtube.com/watch?v=n-hbWO0gL6g&feature=youtu.be

Apologizes to those who have seen it.

[xcitation]

In the case of AF447 the Commander was not on the flight deck and/or at the controls when the event started to materialise.

I take your point about the lack of recent manual flying. This over automation issue has more to it as it affects pilots across a wide range of experience. That said the Captain is the highest authority on the a/c and some say his decision of going on rest and putting control in the hands of least experienced during penetration of CB was a factor. When he returned why did he not take control and instead opted to make a few comments on the warnings? Pitch and power eluded them all for 4 minutes, yet all of them knew how to fly. Notably it was the glider man who was the one pulling back the whole time.

[skyhighfallguy]

maybe the glider guy thought they were in a thermal?

[A0283]

First Officer Remi Emmanuel Plesel has been formally identified on February 10th.

[Lookleft]

I still can't accept that an ex-airforce fighter pilot has 20,000 hours. What age did he join the airline and how many hours did he have when he left the airforce? My point being he may not have been as experienced as others are suggesting. If he did have that many hours at age 53 after an airforce career then he was flying a lot of hours every year.

[skyhighfallguy]

vilters

why would I put the gear down? and the other things?

And while banking the airplane may bring the nose down, I have never heard it called a cartwheel.

[Vilters]

The engines are under the wing, under the center of mass and under the center of lift. Pushing the power up creates a momentum that pushes the nose up.

Pushing power up pushes the nose up, and at the same time you have to push nose down to break the stall. Result?? Nothing changes. The engine power pushes nose up and you push nose down. => You stay in the deep stall.

Chopping the power to idle creates the opposite momentum and drops the nose, helping the stick nose down momentum around the center of mass and the center of lift.

Lowering the gear adds drag below the center of mass and center of lift, and lowers the nose.

ALL tools are good tools to drop the nose.

Banking yes, helping the bank with power on one side, yes.

On realy large planes carefull with rudder, as the fuselage and tail are not build for torsional loads.

[skyhighfallguy]

Vilters

while some of this is true, you are making things harder than you need to.

Pushing forward on the control stick, and with the airbus, trimming forward too should be enough.

While engines can bring the nose up, having the engines providing thrust would allow for a better acceleration.


And while the gear may shift things, the drag later on would reduce acceleration.

Stick forward, trim forward, bank if you can't get the nose down, but all the other stuff makes a recovery difficult on the other side.

[Vilters]

You talk about banking.
In a fully developped deep stall, you have no aileron control any more, no rudder or elevator control any more.

All you have left is use assymetrical trust to get the nose to turn, bank, and eventually drop. Usually one wing unstalls first, and you flip past 90° of bank (the cartwheeling part) but you have the nose down.

Regain speed, and regain air movement over you controls.

Regaining speed is regaining airflow over the control surfaces, speed is life.

[Vilters]

@skyhighfallguy

Your comments are correct. And an unstallable aircraft should not stall. But.

But see?
You are already thinking about the recovery part, before you got unstalled.

FIRST get the nose down. FIRST break the stall.

In a fully developped deep stall, you are dropping like a stone in this thin air, there is little time.

FULL nose down on the stick, wait, then nose down on the trim, wait, but not too long, then chop power, then drop gear, there is little time left by now, and you still have to start the recovery part....and you need altitude for that too.

If nothing helps? Asymetrical power and prepare for (perhaps) a flip/cartwheel, when one wing stalls unstalls before the other wing, perhaps even passing inverted.

The wing drop/flip part is clearly visible in the other video about the ATR. The assymetrical stall roll rate is "fast", and you have NO airspeed over your control surfaces yet to counter it. You have to wait for the speed to come back before you can start regaining control of the roll rate and the nose.

[Leightman 957]

Vilters, I don't mean to challenge you, rather to note there has been some lengthy previous conversation--correction--broadsides right here regarding whether a deep stall of long duration was even possible not to mention probable. If, ensconced as many forum readers are in the quiet comfort of their homes, with either a hot or cold tall one within arms reach, such a conversation could consume group minutes or in some cases hours, not the paltry time available to the pilots in question.

>You are already thinking about the recovery part, before you got unstalled....

Exactly the emphasis one is taught in the present day.

[Machinbird]

If nothing helps? Asymetrical power and prepare for (perhaps) a flip/cartwheel, when one wing stalls unstalls before the other wing, perhaps even passing inverted. Yaw rates in a stalled jet aircraft are extremely hazardous. Just asking for a spin.:{

[xcitation]

Lookleft
I still can't accept that an ex-airforce fighter pilot has 20,000 hours. What age did he join the airline and how many hours did he have when he left the airforce? My point being he may not have been as experienced as others are suggesting. If he did have that many hours at age 53 after an airforce career then he was flying a lot of hours every year.

Sounds like he had to work his way up in both the Air Force and Airlines. No fast track Academy or short cuts.

Iriyanto joined the air force for a 10-year service term, climbing the ranks to first lieutenant flying F-16 and F-5 fighters.
Iriyanto worked for PT Merpati Nusantara Airlines as an instructor for Fokker 27 aircraft (Twin Turbo prop).
He joined AirAsia after his then-employer PT Adam Skyconnection Airlines ceased operations in March 2008 following three plane crashes in a year.
Of his flying hours, 6,053 were with AirAsia.
more than 20,000 flying hours under his belt in a career that spanned three airlines

Iriyanto “is a good flier, procedural, and considered outstanding,” Hadi Tjahjanto, a spokesman for the Indonesian Air Force who trained with Iriyanto, said by phone from Jakarta before the news that debris had been found. “He was classified as a fighter pilot and acted as an interceptor should there be suspicious planes around. So speed in taking action is essential.”

[Sailplaneflier]

I'm confused.

FCOM (http://www.efbdesktop.com/flight-controls/sys-7.5.3.html):

The Flight Augmentation Computers have three main functions:

Rudder trim
Rudder travel limits
Yaw damping inputs
Alternate yaw
Flight envelope and speed computations
Wind shear detection

Can it be said that the FACs rely upon pitot tubes (three of them, but nothing else) to determine the aircraft's airspeed?

Can it be said that in the case of double FAC failure (http://www.efbdesktop.com/flight-controls/sys-7.5.4.html) that the aircraft will revert to alternate law -- with reduced protections?

Can it be said that the FACs might interpret (misinterpret) rapid airspeed fluctuations known to be associated with crossing shear layers / windshear, and implement overspeed protection trimming the aircraft nose up (http://www.atsb.gov.au/media/5246614/ao-2014-049_final.pdf.pdf#page=6&zoom=auto,-274,480)?:


Flight crew operating manual(FCOM)and standard procedures
•Until mid 2013, there was only a descending aircraft over speed prevention checklist That checklist included disconnecting the autopilot and raising the aircraft nose.Use of that checklist in the cruise was inappropriate because it could result in a significant altitude exceedance at high speed and manually flying the aircraft at high speed and high altitude was not practiced often.
•Airbus published new flight crew operating manual (FCOM) procedures for overspeed prevention and recovery. Both checklists commence with AP (autopilot) :KEEP ON
. A newsletter distributed to company flight crew contained the new overspeed recovery FCOM but not the overspeed prevention FCOM.
•If the autopilot remained engaged during an aircraft overspeed flight envelope speed protection is provided in the relevant AFS modes, resulting in a nose up order within the limit of the autopilot authority to reduce or stop the airspeed increase
Can it be said that once a UAS event is triggered, the AP disconnects but A/THR remains active, the FDs remain active and the FAC / protections remain active (to the extent the FACs have reliable - or unreliable information?)

In the event of rapid transient true overspeed while crossing shear layers associated with thunderstorms, is it reliable to depend upon FACs and pre-programmed overspeed protections (http://www.atsb.gov.au/media/5246614/ao-2014-049_final.pdf.pdf#page=6&zoom=auto,-274,480)? Taken a step further, can perceived overspeed protections affect the SS nose down / manual pitch trim down a pilot might apply?

After entering alternate law, due to UAS prompting dual FAC disagree / failure, at what point does the FAC drop itself out?

Automatic pitch trim (http://www.efbdesktop.com/flight-controls/sys-7.3.5.html) stops trimming nose down momentarily at VMO or MMO. This provides a momentary pitch up when high speed stability is active, but automatic trimming will continue if over speed is continued by pilot. An aural "crickets" warning will be heard at VMO plus 4 knots or / MMO plus .006M.
High Speed Stability may or may not be available in alternate law depending on the type of flight control failure.If a zoom climb/ambient air temperature change/violent updraft, etc., resulted in the aircraft being out of its envelope, in 'approach to stall' does the FAC drop itself out after it has sensed the aircraft approaching a perceived stall speed or does the Augmentation Computer still try to 'help':

The VSW is defined by the top of a red and black strip along the speed scale. It represents the speed corresponding to the stall warning, as computed by the FAC (http://www.efbdesktop.com/flight-controls/sys-7.3.6A.html)s.When do the FAC / protections cease having any effect on pilot inputs / pilot directions?

Is there any way to turn them off -- if, say, you were already close max alt, nearing coffin corner/impending stall, yet encountering more turbulence/windshear and HAL wanted more nose up?

When the A320 encounters (http://www.atsb.gov.au/media/5246614/ao-2014-049_final.pdf.pdf#page=6&zoom=auto,-274,766) wind condition changes in the cruise similar to shear, the airspeed can increase quite quickly and this is not a rare event on the A320. During flights between Melbourne and Gold Coast/Brisbane airports, this windshear/wind speed change and potential overspeed situation is not uncommon as the aircraft transits the southern jetstream. AIRBUS SAFETY LIBRARY (http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-ADV_WX-SEQ02.pdf)
II.2 Defining Windshear

Windshear is defined as a sudden change of wind velocity and/or direction.
Windshear occurs in all directions, but for convenience, it is measured along vertical and horizontal axis, thus becoming vertical and horizontal windshear:

Vertical windshear:
−Variations of the horizontal wind component along the vertical axis, resulting in turbulence that may affect the aircraft airspeed when climbing or descending through the windshear layer
−Variations of the wind component of 20 kt per 1000 ft to 30 kt per 1000 ft are typical values, but a vertical windshear may reach up to 10 kt per 100 ft.

Windshear conditions usually are associated with the following weather situations:
•Jet streams
•Mountain waves
•Frontal surfaces
•Thunderstorms and convective clouds
•Microbursts.Influence of Windshear on Aircraft Performance (http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-ADV_WX-SEQ02.pdf#page=3&zoom=auto,-274,614) The flight performance is affected as:
• Headwind gust instantaneously increases the aircraft speed and thus tends to make the aircraft fly above intended path and/or accelerate

• A downdraft affects both the aircraft Angle-Of-Attack (AOA), that increases, and the aircraft path since it makes the aircraft sink

• Tailwind gust instantaneously decreases the aircraft speed and thus tends to make the aircraft fly below intended path and/or decelerate.

Windshears associated to jet streams, mountain waves and frontal surfaces usually occur at altitudes that do not present the same risk than microbursts, which occur closer to the ground.I don't see thunderstorms there.... :confused:

[Trackdiamond]

How do you define "oldies"?*Apparently 20'000 hours did not help in this incident:

Flybob explained the advantages of experience and wisdom that come with it succinctly.Try and put a compliment of two non experienced modern pushbutton automation SOP regurgitating robotic crew in a cockpit with no experienced hat supervising their oeration and a severe abnormality cocks up! Something similar or worse than AF447 might transpire. Where experience comes in is how it can reason with thise SOP and know when it is wiser to deviate from them to be able to save the day..and have the confidence and executive powers to implement the judgement effectively...and. if you ask the youg lad or lass on the side they might be so out of the loop in catching up to what's going on...it makes them even wonder if they are qualified enough to be sitting in that flight deck!Most likely the Captain has to explain through the actions to bring the youngster upto speed.
Whoever quotes KLM/Pan Am accident..it was a concoxion of various causal factors amongst which admitedly the KLM Capt was one of them.Missed radio communication and foul weather with incorrect ATC phraseology all played a part..both KLM PanAm and the Tower made mistakes that day and the swiss cheese was penetrated.

[Sop_Monkey]

Vilas

Apart from the 3 primary controls you mentioned, they also have spoilers, which are very effective for lateral control. They had airspeed, so they would have been effective.

I don't think the poor guys knew they were in a stalled condition, period. Misdiagnosed as you mentioned. There appeared to be no attempt to get the nose down. You would have noticed on the way down, they did have lateral control. I noticed when bank was evident, intentional or not, the nose did lower. So from that I take it they would have known how to get the nose well below the horizon, should they have wished.

The stall behavior data appears to be available, so it should be programmed into simulators. Unfortunately not the recovery data.

Just my observation.

[PT6Driver]

For those advocating spin training in light sep and mep, all very well and good.... but...
This would involve time out from line flying and the accountants will say ... no!
A large number of airlines are very rigid in their application of sops this means 400' ap on, minimums ap off, or autoland. Hand flying is not encouraged full stop. Far less in RVSM .
The result is that basic hand flying skills are rapidly degraded, therfore how long will the stall training be valid for ? To be of any use it needs at least annual refresher and this leads us back to the accounting department.

Stalling. The primary reaction has to be the reduction in AoA. If you apply full power/toga it is more than likely you will get an uncomanded and uncontrollable pitch up.
No one flys airliners close to the stall deliberately, therefore the reduced speed has gone unnoticed. The aircraft will be on AP and will therefore have trimed for the slowing speed. When the AP gives up you have an almost full nose up trim, add in power and it will surprise surprise pitch up.
Witness: AF, Colgan, Bournemouth 737 etc
Application of power has to be applied relatively slowly along with rapid trim nose down. But first reduce AofA!

[training wheels]

I still can't accept that an ex-airforce fighter pilot has 20,000 hours. What age did he join the airline and how many hours did he have when he left the airforce? My point being he may not have been as experienced as others are suggesting. If he did have that many hours at age 53 after an airforce career then he was flying a lot of hours every year.

He left the airforce in 1994 and then joined Merpati Airlines flying F27 and F28s before joining Adam Air flying 737s. He later joined Air Asia after Adam Air foldered. Air Asia Indonesia started with a fleet of 737s in the early days, before they went to an all A320 fleet.

[Capn Bloggs]

For those advocating spin training in light sep and mep, all very well and good.... but...
I've said it before an will say it again: we don't need spin training, per se. IMO all we need is good hand-flying IF skills. We should then be able to fly safely when the AP spits the dummy or diagnose the situation and recover (eg AF447, which wasn't in a spin). We all go to the SIM every 6 months. A 1/2 hour, non-jeopardy, of flying around on raw data (including enjoying oneself eg wingovers, barrel rolls) together with eyes-closed U/A recoveries would go a long way to improving our ability to take control of the aeroplane when the situation goes pear-shaped.

Of course the bean counters will go ape; the regulatory authorities should have the balls to regulate it into the SIM programs; then it's a level playing field for all.

[RetiredF4]

Although this thread is about the lost air asia aircraft and we still do not know what happened in detail, one discussion focused on stalls and the way to recover from those.

Vilters
I am a pilot.
Flew light to medium, even have a BFM (Basic Fighter Man) hr in an F-16B, and yes we pulled the whole 9G's a couple of times.

No, all those "Thousands of hrs" airline pilots do not need a single extra hr in a simm. NOT a single hr.

They need "REAL" seat time in a Cessna 152, a Pitts, or a Cap10.

They "need" some "REAL" and "DIE HARD" stalls to cope with, not in any simm at all, but in real life.

Where their bottoms come loose from the seat.
Where the break drops the nose deep and the wings fall ways from you.

I'v had "real" pilots turn white as paper.

I'v had guys shouting and screaming; sweating and strugling.

All they ever did was; "Stay away, stay away, recover before the stall."

Well, I fear the results speak for themselves.

And then do a full deep stall in a twin.
And teach them to cartwheel out of the stall. Full rudder and Full power on one, chop the power on the second, and cartwheel overhead out of the stall.

Then you will have pilots that start to understand stalls.

You might see some pilots turned WHITE, but you"ll have better pilots.

You can put them in a sim for weeks, nothing will ever change.

I do agree with a lot what you are saying.
Doing stall approaches and stalls and revovery from those in the sim might be usefull as an procedural thing, but it will never be able to replicate the physical behaviour of the aircraft and its influence on the human brain. To understand stalls and their influence on the human body and brain you have to have first hand live expierience of of such a situation and the necessary recovery steps, as the recovery will be even more uncomfortable than the stall itself.

Recognizing the stall:
The stall entry might be smooth and gradual with modern FBW aircraft, preceeded with some airspeed decrease and increase in pitch, maybe some vibration, and then the ship does not follow the commands like it should, descent rate will increase while some wing drop might occcur. That is unusual, but it is not asociated with alarming loadfactor changes or violent maneuvering. Therefore stall warnings should always be treated as real unless proven otherwise.

Breaking the stall:
Already the first step for the recovery, to reduce the AOA by bringing the nose close to the flightpath is a maneuver never performed before, the change of the loadfactor from 1g to 0g and the immidiate never before expierienced sensation of weightlessnesss of the body will make one sweat. The arm on the SS will no longer be supported by the armrest, or the arm on the steering horn will not rest on the upper calf, Legs will not stay on the floor by themselves, papers and stuff flying around, a completely differnt situation from the one just seconds before. Combine that with the need to act against long trained reflexes, to disregard the altitude loss, to disregard the bank angle, to drift off from the intended course, to pull power levers back instead of advancing them and to deliver the passengers a load of discomfort and even the risk of severe injuries. The next task is to maintain this input long enough, which will most probably lead to a never expierienced nose down pitch position, which in connection with the 0g loadfactor will give the sensation of surreal acceleration.

Recovery to normal flight attitude:
When the stall is broken and flying airspeed is regained the recovery has to be initiated immidiately to prevent an overspeed, but with enough care in order not to overstress the airframe. Power has to be adjusted to manage available energy. Secondary stalls are a common occurance in stall encounters, therefore concentration should focus on regaining a level pitch and bank attitude and stabilize the normal aircraft parameters. Regaining lost altitude, regaining navigation and informing ATC are of secondary importance to attitude and speed.

CRM under stall encounters
Both crew members have to be trained to the same standard, that the PNF understands and accepts the maneuvers flown by the PF and asists with the appropriate informations, speed being the most important of all, while a myriad of warnings are blaring and the ECAM puts out messages faster than one can read. Out of control response was a briefing item for every flight with my weapon system operator, so he would know what my plan of action was.

Look at the posted BEA video, how fast and gradual everything happened, bad that it does not incorporate the nz graph. The AF447 crew failed in all of the above parts, they had no chance.

Wishlist for training
It is not a situation one wishes to encounter unprepared. Most important would be a thorough introductionary course with lessons, sim training and some real stall demonstrations / practice and recoveries. A refresher course should be mandotary when changing type or after elapse of a predetermined timeframe.


I do not agree in the application of lateral control inputs by flight controls or asymetric thrust. In a stalled situation those inputs are pro spin inputs like Machinbird correctly says, and no skygod will get an airliner out of a spin. Those tails on transport aircraft have mighty control surfaces, correct usage (trim and elevators) should give enough authority to reduce the AOA.

Thanks to the mods in allowing these discussions, although we do not know yet if they are relevant to this thread.

[RAT 5]

Then you will have pilots that start to understand stalls.
You might see some pilots turned WHITE, but you"ll have better pilots.
You can put them in a sim for weeks, nothing will ever change.

Great fun; been there, done it; great idea, BUT......

Sadly the airlines philosophy is "sim time costs money and it is only necessary to perform the legally required basics." They have then covered their backside. Sim costs money; pilots not in a/c costs money; hotels travel to/from costs money etc. etc. Their prime idea is to train their pilots to keep well away from the dangerous part of the envelope. SOP's will ensure that. Meanwhile I hear the students spouting the new TEM mantra before any phase. What are the threats? If they can't perceive any they invent them. No-one ever says Mother Nature & Gravity. You are in a hostile environment where you ain't supposed to be. The shark is trying to bite your tail and the crocodile is waiting to pounce on the unsuspecting. If you put your foot in the water and get snapped at you need to know what to do. That's the thinking of the suggestions above. (you might see some pax turn WHITE, and you may not see them again, but they'll be alive.) I doubt the XAA's will enforce such items, and no airline will do it of its own initiative. They will quote cost/risk management and say how many times in a career will a pilot need such skills (risk) and what would it cost over a career to keep them up to speed? Every 3 years I jumped through the UA upset program. Rubbish, but box ticked. All the pilots on my B737NG I spoke to, including the trainers, did not know there is a stick nudger. (At least there was when I first went on type. I used to demo it.) Now they only recover at the shaker. I also admit that before Boeing introduced the new (old) 'unstall the wing first' idea I used to teach it. Attitude first then power. Split second, no more. Since when did Seattle or Toulouse redefine aerodynamics? I did also demo the stick-shaker power only recovery with autopilot in ALT HLD. It was scary, but educational. I did this at various levels to show the capabilities of power over aerodynamics and the effect of thrust reaction at different levels. It was a full in-depth exercise. Took a while, but once seen never forgotten. Then a new syllabus was imposed and job done in 10 mins to minimum requirement.
So don't hold your breath waiting for change. A few more enlightened C.P.'s & HOT's and CFO's might help. Best o' luck.

[mseyfang]

@RAT 5

Interesting that you mention TEM. Part of TEM is the ability to handle things when they go south and that definitely includes autopilot malfunctions. For reference: http://flightsafety.org/files/maurino.doc

TEM and CRM are, IMO, useful concepts in theory as conceptual frameworks for many of the issues under discussion here. What many posts have discussed is that they are worthless without basic airmanship skills. In other words, recognizing autopilot/autoflight malfunction as a possible threat, while not equipping pilots with the handflying skills needed to react properly to that threat is tantamount to recognizing a threat without giving pilots the skills to counteract that threat.

I'm a big believer in CRM and will defer to Al Haynes on his opinion of the concept, which is far more eloquent and rooted in experience than mine could (hopefully) ever be, though I have found over the years that CRM has made me a better pilot by giving me a concept through which I can learn even as I age. Those who point to Tenerife as the primary motivator for CRM haven't read their accident reports. UA 173 in 1978 comes to mind; there are others.

With respect to TEM, I think we have a concept that is sound in theory as a way of looking at things but which comes up short in execution. TEM should not be a mantra, it is a way of looking at risk management. Where I think things may be out of alignment is that some may be capable of reciting the concept without the skills to back it up and in that respect, you're correct, it has become a mantra rather than a conceptual framework that requires judgment and airmanship which with to back it up.

[Ask21]

Vilters /RetiredF4 and others.

My exsperience with stalls is from gliders. There you could absolutely stall the plane - and induce a wing (and nose) drop by applying some rudder. It would get the plane out of stall and into a steep dive - the recovery was high speed and involved some positive g.

Along these lines:
Would it be OK to ad some drag (extend the weels) - both to get the nose down - but also to have some extra drag so the plane will not accelrate that fast during steep dive phase of stall recovery?

For the traing part. Would it be an idea for professional pilots to take a few starts in a glider with a acro-glider instructor - just to "feel the stall forces" and get some first hand stick and rudder practice in this field.

Also - Let say you start in a fully deep stall with little or no authority on the control surfaces. What are really your options? Elaborate on that. The airstreams is coming from below allready and as you start diving your speed downwards increase but you may still be stalled? How deep dive would you need at minimum to get out?

What about spoilers and even 5-10 flaps - slats. What would it do? .
Also from my training as a glider - the diving spin was not that feared - it was rutine practise. The one feared was the "flat-spin" - Could a one side engine power induce a flatspin" - Could rudder induce a flat spin. Can you be shure one wing drops to induce dive? Also, since at the stall the plane is generally at a low speed - will the rudder really have the capability to break the plane if used to hard

To the extreme - could you unstall a plane in a deep stall by applying reverese thrust moderately?

[Machinbird]

Also - Let say you start in a fully deep stall with little or no authority on the control surfaces. What are really your options? Elaborate on that. The airstreams is coming from below allready and as you start diving your speed downwards increase but you may still be stalled? How deep dive would you need at minimum to get out? Another technique that may be useful is rocking the plane out of a stall. Sort of like rocking your car out of a slippery spot. But first, get that THS trimmed down toward a ~300 knot setting. You know where that is, right? (Assuming you are flying a jet aircraft :})

[Sop_Monkey]

Apply 90 degs bank and no extra nose up elevator/trim the nose will drop, let me assure you. Weather cock, tail feathers...

As you said extend the gear, anything but unload the wings, whatever you do and get it pointing down hill. The gear and the speed brakes would help control the speed on the way down.

No real need to have asymmetric power, as it could cause extra complications.

[Trackdiamond]

Are FBW aircraft more susceptible to stalling when flying in severe weather? If so should it not be mandated that FBW pilots be given stall recovery training in the actual plane as part of base training as obviously sim training even if level D sim..hasn't been adequate. To ensure stall recovery in real flying.It can be practiced in clear weather but with certain simulated faults (system off..such as AOA and some probe heating off and remain with only the ISIS for reference to purposely disorientate the student but with Instructor able to view flt parameters and how the student is recovering.
I reckon it won't be long before we have another irrecoverable stalling accident by FBW aircraft flying through some ITCZ or other severe weather..if nothing is changed in training methodology.:ugh: unless perhaps Airbus designs a STALL recovery button that works independently based purely on accelerometers and GPS..and when executed will retard thrust and auto pitch down like stick pusher and when speed builds up(based on GPS determined speeds do an auto recovery.Surely after designing a sophisticated FBW systen this should be simpler to design and incorporate by comparison?

[RetiredF4]

Stall recovery training and even spin recovery training is in the syllabus of most military training schemes. I did full developped stalls and spins in the T37 Cessna, and later recovery from some unplanned stalls in the F4. It never was routine, each of those planned or unplanned stalls were a challenge.

Let's concentrate on doing the recovery in the most simple way first, it will work in more than 90% of all those events. Reduce the AOA by applying nose down input and nose down trim, consider reducing power, but at least do not add power. When the aircraft is unloaded at about 0g, you are not stalled anymore. Now accellerate by gravity and if necessary by smooth power application to flying speed, while maintaining this loadfactor close to 0g. Level the wings to the nearest horizon, then start a controlled pullout to level flight.
It is a step by step procedure, one has to be patient to let the contol input become effective. Any kind of premature change of configuration, thrust or drag will change the whole equation again with consequences for the next steps.

Concerning the bank angle it would be a great achievement to let the bank angle develop by itself ( which it does anyway in disturbed airflow) and accept it as help in getting the AOA down instead to counter it.

Any bank steering input or assymetric thrust change might induce yaw and kick the aircraft into a spin. It does not have to be a flat spin, any spin for a normal crew in a big transport aircraft will be deadly. There is no time to check out how much yaw dampers or limiters are still working which might prevent such a spin entry. Keep away from these possibilities as long as possible.

Although gravity is a mighty force, it is easily countered by flying machines. If the power is used with caution in the recovery phase i see not much problem in doing a pullout without overspeeding or overstressing the airframe. Lets keep it simple, plan on keeping the gear and flaps where they are at the beginning of the event as long as possible.

I have not flown gliders, but they would not be my choice for stall recovery training. There are lots (cheaper than sim time) aircraft available to demonstrate the necessary steps and feel the unloads for recovery.

But fiinally it is not only a question of funds, it is also a question of will.

[RetiredF4]

Ok465
Thank you for your point of view, which is a valid one and it was not my suggestion to train the stuff like we did in UPT. I hated stalls and falls from the beginning and could not understand, how some could love that uncoordinated falling.

There are three effects influencing a successfull outcome, the procedural part, the type specific part and the physical part. While the first two can be trained in classrooms and present simulation systems, the physical exposure to the forces in a stall event from entry to successfull recovery can not be replicated in present sim, at least not that I know off. The german military uses one centrifugal gadget which is good for positive g loading, but afaik no good for the opposite.

My line of thinking concerning the failures in multiple accidents to break the stall by putting the SS or control column to the forward stop when necessary is, that the effects such an input would have during normal flying is preventing the crew to even think about it or to maintain that input long enough. There must be reason for that, and it is human not to deliberately go into unknown territory. Therfore as soon as some unloading is expierienced like it happened in AF447 case (see the Nz graph and compare it to the following pitch control input), it is followed immidiately by the opposite input to get rid of this unfamiliar unloading.

Exposure to such an maneuver in any suitable aircraft will aid in more tolerance to this physical effect and would provide some knowledge what to expect during such recovery. The real problem is, that this "Angst" already influences the early avoidance of stall entry in a negative way.

The sim for such training is just a box, a very clever one which can trick the senses in believing all kind of movement, but there is none where the g loads are generated in a usefull way. We all know that transport aircraft should be flown with minimal loadfactor changes, smooth and comfy for the passengers and that's the way aircrews are trained. But that does not help at all in approach to stall and stall recovery events, as the near past has shown.

[Cloud Cutter]

RetiredF4, that's an extremely good point.

I think an interim measure could be to ensure stall training includes a well emphasised disclaimer that reduced G-force is likely to be experienced during recovery, which the simulator can not represent adequately.

It shouldn't be a stretch for most pilots to then make the link that the feeling of reduced loading confirms the efficacy of the maneuver, which is designed first and foremost to unload the wing.

The best way minimise the psychological effects of the unexpected, is to make it expected (or at least plant it somewhere in the back of the mind).

[tommoutrie]

some of you chaps are talking about very aggressive maneuvers to recover from a stalled condition. Once you've unloaded the aircraft to zero G and the angle of attack is accordingly reduced it can't be in a stalled any more. Obviously you then need to wait for the aircraft to accelerate but I don't really understand why shoving masses of negative G makes any difference. But the problem appears to be much more basic than that. Experienced guys are not making any kind of stall recovery - in the case of 447 it appears they didn't even realise they were stalled. Assymetric power, rolling to knife edge, mucking around with the gear and whatever else has been suggested may be a technique that Chuck Yeager would use when all else fails but surely a stall recovery should be relatively simple for any pilot. Recognition is the problem, not recovery. I am an average pilot and I am shocked that other blokes like me can get so overloaded that the bloody obvious is not a possibility they consider. Surely, if it can happen to them, it can happen to me and most of you. Its not the ability of the blokes to fly the recovery - its the recognition of whats going on

[RetiredF4]

tommutrie
some of you chaps are talking about very aggressive maneuvers to recover from a stalled condition. Once you've unloaded the aircraft to zero G and the angle of attack is accordingly reduced it can't be in a stalled any more. Obviously you then need to wait for the aircraft to accelerate but I don't really understand why shoving masses of negative G makes any difference.

Let me point out some misunderstanding here.

Nobody is talking about masses of negative G. The aim is 0 g, as that will take the load off the wings and unstall the wing regardless of airspeed. 0 g is however a big number for someone, who has never expierienced less than +.9 g by his own hands in his thousands of flying hours. From the physical stress we could compare it to pulling +4 g, as positive g' are more tolerable.

0 g is not reached by gently putting the SS or the Control column a bit forward of neutral when stalled already. That kind of control input might be sufficient in the very early state of an entry into the stall when the AOA is close to the max allowable AOA, but it will achieve nothing when the AOA is excessive. Depending on different factors the AOA will decrease very slowly ( and the load factor in turn as well) even with a full nose down pitch input, which then has to be gradually released when the AOA decreases. Once the 0 g, representing 0 AOA is reached, maintain it with whatever control input it takes until the airspeed is sufficient again for recovery.

Maybe we should use a differnt word for agressive, I think I tried to avoid it in my arguments, let' s call it a decisive maneuver, an immidiate reaction to the stall warning with the correct procedure to migitate the danger to drop deeper into the stalled regime while accepting that management and passengers will not like the fallout of such a maneuver.

[Leightman 957]

RetF4 thanks for your several well thought out posts. But your conclusion that early stall avoidance may require uncomfortable and never before experienced sensations (dirt, papers, coffee, and appendages rising) that will in many or most people inhibit proper actions appears to me to seamlessly morph into a prediction of lingering angst resulting from any exposures to sub G training "in any suitable" AC. You term these physical benefits as improved "tolerance", 'tolerance' suggesting an increased ability to withstand a discomfort. Perhaps my sub and negative G introduction and subsequent investigation was different, and that probably people in general will have widely varying reactions, but I think a distinction should be made between "tolerance" and "familiarity".

I may learn to become tolerant in the dentist's chair but I don't know if I will ever become as able to act with as much speed or finesse or total SA sitting there with the drill screaming if the chair also jumps off the floor, the building begins to sway, and the fire alarm goes off. "Familiar" however implies a reaction where a sensation has become so well known that the fear of it or angst about it has been surpassed. (However I don't suggest that training to familiarity in the dentistry illustration would ever reach a place of personal ease:-)

I realize I am drawing a fine distinction here, but I don't think it is negligible.

I know that if I had a choice between a pilot who I knew tolerated sub or neg G, and one who was entirely familiar with it, I would choose the latter. I also know that if I knew one airline for which zero awareness or minimal tolerance was the norm, and another where all aspects of piloting were encouraged to be explored for all anticipated flight regimes, I would also clearly choose the latter. It has come as something of a surprise to me to find that the airline industry has evolved to systemically include as much aviating slack as has been reported here.

High altitude stall events as under discussion now are rare, but I don't see that at as any reason to avoid comprehensive training covering anticipated flight regimes, especially when once a stall has been entered there is along with a lot of brand new potential circumstances, a relative dearth of Plan B's. Training today certainly includes other equally rare events that are thought to be essential. Acro aircraft and pilots looking for any excuse to bore odd shaped holes in the air are sprinkled everywhere around the globe everywhere and are cheap compared to dredging the occasional large aircraft. I'm not suggesting acro sequence training for everyone. All we are looking for here is a cheap effective erasure of angst. But like any piloting skill, such exposure demands currency.

Cloudcutter suggested that an intellectually (not physically) informed anticipation of a set of sensations will be sufficient. My experience taught me any never-before-experienced sub or negative G sensations, particularly combined with stress, is going to leave one less able to respond no matter the amount of intellectual preparation.

[OzSync]

Most of this discussion seems more AF447 related, given the lack of information regarding the accident this thread refers to.

tommoutrie makes the point that the issue today is more the recognition of the stall. Not the recovery.

Airbus and Boeing have tightened up their stall recovery techniques and they aren't really the issue here.

Certainly in a Boeing it is very simple:

Push down trim down until the stall indications stop.

Unreliable airspeed is also pretty clear cut now:

If in doubt straight away set a specific attitude and thrust setting then troubleshoot.

Recognition and prompt CRM and action is the issue, not the recovery technique.

[xcitation]

Failure to identify stall is indeed remarkable. You have highly qualified pilots looking at stall warning lights & sounds, crickets, an PFD pointing up 10 deg, airspeed decaying to below 60knots, vsi max'd down, altitude tape unwinding like you never seen before. What else can the a/c possible do to tell you?
Some have suggested a stick shaker, then pusher. Not convinced that that would help or just add to the confusion.

[Centaurus]

One A320 simulator training syllabus included setting up the aircraft for practice stall recovery with ALT LAW.
The high altitude part was conducted clean at 25,000 ft. Hardly "high altitude"I would say.. The next was conducted first at 12,000 ft clean and then in the landing configuration at the same altitude. Nothing in the syllabus about IMC or VMC. To be realistic it should be in IMC where manual instrument flying skills would form part of the practice.

In view of recent loss of control events in Airbus aircraft which happened around 35,000 ft or above, it could be argued that stall recovery practice in the simulator should be conducted at that altitude or higher. After all that is where the accidents started.

Practicing a stall recovery at 12,000 ft in the landing configuration seems a trifle illogical since very few airports taking jet transports are that high. It would be more logical to conduct a landing configuration stall recovery on short final since recovery requires minimum loss of height for obvious reasons. As most pilots are aware, stall recovery technique is entirely different at high cruise altitudes compared to (say) 800 ft agl when the aircraft is in the landing configuration.

[IcePack]

Centaurus, trouble is the Sims (in general) are not programed to be representative at 35000 they handle the same as they do at 15000. + the stalls are not representative eg hold full back stick on a 330 sim at 35000 with an aft cofg (38%) and after some buffet the nose will drop. I.e conventional stall. But we know that this is not the case. IMHO this is criminal. Much of the stall teaching on sims is negative training. & no you can't do it for real as the aircraft "might" break if mishandled. So how would the crew really know what to expect of a FBW stall. I certainly don't (I can guess) & I've been flying them for 10 years or so.

[captains_log]

Stall speculation aside.

When is the actual preliminary report due out? I thought it was late Jan?
Due to the fact they were keen(maybe not he best word) to cancel the majority of the salvage operations, surely the investigation team have a clear picture with the aid of FDR/CVR of what happened?
If so what's with the delay?

[charliemouse]

An airframe every year or two falling out of the sky from cruise killing hundreds.
Sims not accurately programmed to train for scenarios that can and do happen in extremis.
Is it time to fit an ejector seat in an old 319/320 airframe and possibly also 330 and send a test pilot up to find out what REALLY happens. What the plane really handles like. What the recovery techniques all current pilots on type would lead to if done expeditiously. And not.
I'd prefer a man with an ejector seat to find out on his own that "putting 90 degrees of bank angle on to drop a wing and get the nose down" can be done, retains control authority an structural integrity. Rather than when I'm sat in seat 9A reading my book and planning a nice weekend.
Just saying...

[Ian W]

If the aircraft requires an ejector seat for pilot safety if it stalls/spins then I am not sure it should be certified as a commercial airliner. :sad:

Test pilots have deliberately test full-stalled various airliners without a bang-seat in the past, so it is something that can be done.

[charliemouse]

Test stalled sure - but at or close to service ceiling? With a simulated full load, an imperfect trim with rearward CoG and perhaps some loss of situational awareness? (ie in a thunderstorm at night, rather than a clear day).


I fully appreciate the economics and the "tombstone imperative", however there are a growing number of the latter and what is clear from this thread is that there are few if any with any clear idea of what happens when a FBW aircraft enters coffin corner and then finds the corner. The sim is no help if its working with duff data. Passing a sim check or even playing with the sim in some rare free sim time is no bloody good if the real thing is different.

[Sop_Monkey]

If, in high altitude stall test, for real with a test pilot(s) on board, they cannot get the AOA reduced to recover from the stall there is another option as a very last resort. Just to save the test crew.

Why not have a drone parachute attached to the rear of the fuselage? On deployment, the drag from the chute would certainly lower the nose, by raising the tail to a sufficient degree for recovery and could be cut away when or if it has done it's job.

One would think this has been thought of by much smarter people than I. However upon learning these aircraft haven't been (intentionally) stalled, leave alone deep stalled at high altitude, one can only wonder at the mentality. The uncrashable/unstallable mindset, does give it a way a bit.

[A0283]

As far as I can read and understand it ...


When is the actual preliminary report due out? I thought it was late Jan?

Yes it is already out at the end of the 1 month period set out by ICAO ... and sent to ICAO and parties involved ... but certainly not made public ... in spite of the expectation of some pprune posters.

KNKT/NTSC have literally stated (look at previous posts - including a translation of the KNKT interview video) that they 'have the key' to the accident.

KNKT suggested that they would have a press conference later divulging more information. Later that changed to - it would be adressed during an already scheduled annual KNKT report presentation - but it was not (as far as I could see - even digging deep in local Indonesian press reporting).

Most public information is from a parliamentary commission presentation of which fragments can be found on-line.

Due to the fact they were keen(maybe not he best word) to cancel the majority of the salvage operations, surely the investigation team have a clear picture with the aid of FDR/CVR of what happened?

The salvage as such already faltered before they had had time to read the flight recorders. So I find that cause-effect highly unlikely.

If so what's with the delay?
I asked that recently. Nobody knows apparently. And most surprising, nobody appears to be upset about that.

Interesting is that originally KNKT stated they expected the final report in 1 year. Recently statements have reduced that to 8 months.

For an innocent bystander it is quite confusing. The state quite fast that they have 'all' the answers. But will publish quite late ... not having a Prelim ... we have to wait at least 8 months for a Final ... which by definition will have a Public version. It would be nice to get some public KNKT explanation of course.

[FullWings]

Sims not accurately programmed to train for scenarios that can and do happen in extremis.
I don’t think that’s as important as people make out. The detailed response of an airframe to “edge of the envelope” events in real life is often highly dependant on things like CG, yaw/roll/pitch angles, asymmetry, entry rate, wing loading, air density and many other factors. Every one is different, sometimes remarkably so.

What needs to be trained is:

1. High-altitude stalls are BAD, don’t go there.
2. If you do end up there, it will most likely need control deflections and pitch angles that you’ve never used/seen before to get out of it.

If the sim is up to replicating that, then it’s good enough. We are trying for a generic recovery procedure, not a specific finessed one.

[xcitation]

Test pilots have deliberately test full-stalled various airliners without a bang-seat in the past, so it is something that can be done.

From an interview I saw with an airbus test pilot, he said that they only test a stall close to the edge of the envelope with high energy. The AF447 and air asia stall are far more lethal because the a/c has lost nearly all energy and have the engines at idle. This requires a lot more time to recover the lost energy. Clearly there is a huge difference between a best case stall and a worst case stall. I think it reasonable to want the ejector seat for a Chuck Yeager willing to take an a/c so close to unrecoverable.

[feedback]

Why not have a recovery parachute attached to the rear of the fuselage?

Don't know. Will it rip the rear pressure bulkhead off, or just pull the tail away when it's unfurled?

[HeavyMetallist]

Don't know. Will it rip the rear pressure bulkhead off, or just pull the tail away when it's unfurled?
He was only talking about doing this to allow test flights to be carried out safely, so it wouldn't be a problem - the test aircraft's structure would be reinforced as necessary. This method is routinely used for fast jet spin testing (although obviously you do also have the benefit of an ejection seat if things don't work out in those circumstances). An alternative would be something along the lines that Airbus have already used for A400M stall testing, a downward-firing rocket in the tail.

I make no comment on whether any of this is necessary, merely observing that it's readily available and deployed technology within the flight test community.

[Clandestino]

From that professional viewpoint you can only be very very happy with the approach taken by the Taiwanese ASC. And at the same time negatively surprised by the approach taken by the Indonesian KNKT/NTSC.Surprised by ASC releasing DFDR readout quickly - yes. Surprised by NTSC - well, not exactly, bearing in mid the outcome of MI185 investigation. Regarding the country of registration and nationality of the captain, stakes are far higher now but DFDR and CVR are read out so evasion will be more difficult.

In the AirAsia case the (investigation) authorities have published few preliminary facts (radar, FDR and CVR data). But have published some short ‘final opinion’ conclusions( {we know what happened} “ we have the ‘key‘ “ – and – “it was not a suicide”).

(...)

In the Indonesian case no-one, not a single mention on PPRuNe I think, suggested a suicide. It is possible that recorders' readouts prompted NTSC to jump the gun.

[Tailspin Turtle]

xcitation
From an interview I saw with an airbus test pilot, he said that they only test a stall close to the edge of the envelope with high energy.

Exactly what is a "stall close to the edge of the envelope with high energy"? I'm familiar with accelerated stalls, power-on stalls, power-off stalls, PA and CR configuration stalls, etc. but that's a new one to me.

[xcitation]

My understanding is that kinetic energy is the work done to accelerate the mass of the a/c. This is increased by engine thrust or trading potential energy (losing altitude and claiming the acceleration from gravity). If you have low PE and low KE then total energy is low which is very dangerous.

Update: Boeing have a good description here...Aerodynamic Principles of Large-Airplane Upsets (http://www.boeing.com/commercial/aeromagazine/aero_03/textonly/fo01txt.html) (Aero Magazine, 1998 Q3 edition)

[fireflybob]

My understanding is that kinetic energy is the work done to accelerate the mass of the a/c. This is increased by engine thrust or trading potential energy (losing altitude and claiming the acceleration from gravity). If you have low PE and low KE then total energy is low which is very dangerous.

It's a while since I did A Level Physics but here goes:-

Gravitational potential energy is the energy stored in an object as the result of its vertical position or height. The energy is stored as the result of the gravitational attraction of the Earth for the object.

So the higher you are (above earth) the more the potential energy?

Kinetic energy is the energy of motion. An object that has motion - whether it is vertical or horizontal motion - has kinetic energy.

KE = 0.5 m (V)squared - where m is mass and V is speed. Double the speed and you quadruple the energy.

[PT6Driver]

X citation and others

Essentially what is being inferred here is that stall testing is done with a lot of potential energy. ie at a high altitude and not close to the ground.
In this context the comments (some of which have been allowed to stay) make sense. One does not practise stalls close to the ground even in a c152!

However your later comments re selecting flight idle and equating that with low energy are incorrect. For stall recovery the sequence has to be reduce the AofA then a short while later increase power. Selecting toga or equivalent merely causes a pitch up which makes reducing the AofA almost impossible.
Increasing the power does not increase'the energy state of the aircraft'.
In a stall situation you do not go faster nor do you increase altitude, you merely descend in a stable stall like AF.

[Gysbreght]

Scale effects well known.Are they? Scale effects are expressed in the Reynolds number, which considers viscosity. Combine that with Mach number, which considers compressibility. Then you'll see the need for full-scale testing.

[xcitation]

To clarify my comment about idle detent; N1 take time to spool up when changing from prolonged idle to TOGA. This is another consideration when a/c is falling out of the sky and flight control is urgently needed e.g. Habsheim incident - low total energy, low N1. The impression I got from the airbus test pilot was that stall testing is done in a very controlled manner changing flight controls as little as possible. This protocol allows the a/c to return to the flight envelope very quickly with only small stall excursions. It's not cutting engines, full stick back, see what happens.

[_Phoenix]

From an image of wreckage, it seems that the screw was snatched during the impact. It remained attached to THS
http://www.mediafire.com/view/1hh6qghm8m58oqb/jackscrew.jpg

[autoflight]

Risk avoidance will minimise the number of pprune threads like this one. The multiple factors that conspire to place a crew in risky situations need to be considered by all pilots. By the look of the number of accidents like this one, not all of us spend some quiet time at home thinking about the various scenarios and the choices that might be available to minimise risk.
It is OK to consider and practice in the sim for recovery procedures under difficult circumstances, but wouldn't it be heaps better to recognise the risk? Finally it is up to the captain, but the F/O is not in a comfortable position as the risk escalates. Some captains will have their own reasons why staying at F390 in increasing moderate turbulance is acceptable in an A320. A lower time F/O might accept an insufficient reason, like ATC clearance, reduced endurance, possibility of diversion or increased turbulence at lower levels.
I see no indication on these pages that companies are pressing ahead with avoidance training. Rather there seems to be so much discussion on recovery.

[PT6Driver]

Xcitation
I take your point re testing in a very controlled manner, however when a real and unexpected stall occurs on the line, those involved have moved very far away from the contrlled environment of testing.
In the Bournemouth incident both crew were pushing full forward on the control column, but were unable to prevent the pitch increasing to arround 45 degrees. My point being that large control input is likely to be very necessary in order to be able to reduce aofa.
Your example proves how far removed real life can be from testing. No one flying on the line wants to go near the stall, but if they do it will be at the most inconvenient momoment and completely unexpected. Having a clear understanding of what to do is vital. Avoidance is the first step then recovery the second.

[Derfred]

I see no indication on these pages that companies are pressing ahead with avoidance training. Rather there seems to be so much discussion on recovery.

I must caution you here: Discussion on PPRuNe bears no resemblance to what companies are pressing ahead with.

Professional pilots are fascinated by other's mistakes (and so they should be) because that's how they learn not to repeat them. The reason threads like these go for hundreds of pages is that professional pilots see a colleague suffer a disaster and they want to know why.

In the impatience of awaiting the final report, they suggest solutions, but most of these solutions come from their creative thinking, not from research of what "those in charge of policy/training/manufacture" are actually doing about it. It's really annoying because those who are actually involved in improving policy/training/manufacture don't jump on PPRuNe every day with an update. Don't they understand the frustration this causes?

However, in direct answer to your question, "avoidance training" is not really something that can be taught in a simulator, or via newsletters/memos, or via flight manuals. This is learned on the line with experience. The only way to learn the best way to fly around thunderstorms is to spend years flying around them under the guidance of someone who has flown around more of them than you have.

Ideally, you fly in the RHS (or in some airlines as a relief pilot/cruise F/O) for many years and learn the avoidance strategies by being exposed to them over many years, with on-the-job guidance and advice from a more experienced pilot in the LHS.

Unfortunately, it doesn't seem to always pan out this way these days. For example, cadetships leading to rapid command promotion in rapidly expanding LCCs, by definition, jump this stage.

The old adage: you start with a full bag of luck and an empty bag of experience. Try to fill the bag of experience before your bag of luck runs out.

But that does not appear to be a factor in this particular accident - the F/O was inexperienced but mature, and the Captain was very experienced. We still don't know why Air Asia pitched up, stalled and stayed stalled. (If indeed that is what happened, we don't know yet.)

The investigators say they know why, but they aren't telling. Again, very frustrating.

In the case of Air France, experience/training was possibly very much a factor, as unfortunately the only chap capable of even recognising the problem (stall) was asleep. The situation may have been unavoidable, the recovery procedure was possibly known to the crew, but they failed to recognise the problem (experience? training?) so did not implement the recovery.

[Ian W]

Risk avoidance will minimise the number of pprune threads like this one. The multiple factors that conspire to place a crew in risky situations need to be considerered by all pilots. By the look of the number of accidents like this one, not all of us spend some quiet time at home thinking about the various scenarios and the choices that might be available to minimise risk.
It is OK to consider and practice in the sim for recovery procedures under difficult circumstances, but wouldn't it be heaps better to recognise the risk? Finally it is up to ther captain, but the F/O is not in a comfortable position as the risk escalates. Some captains will have their own reasons why staying at F390 in increasing moderate turbulance is acceptable in an A320. A lower time F/O might accept an insufficient reason, like ATC clearance, reduced endurance, possibility of diversion or increased turbulence at lower levels.
I see no indication on these pages that companies are pressing ahead with avoidance training. Rather there seems to be so much discussion on recovery.

On the contrary, it is companies that have only been doing avoidance training that has led to the current state.

* Anyone flying manually outside the immediate landing or takeoff gets snitched by FOQA and told to desist: the automatics are better than you are and this avoids the risk of something going wrong.
* If this (alert/instrument fail/behavior) happens then memorize this list of precise instructions and follow them. Get the PNF to read through and check that you have done them and nothing else.
* Sit in this reasonable simulation with critical unrealities every month and improve your by rote response to specific (alert/instrument fail/behavior)

These are all risk avoidance by the aircraft operators. To some extent one can understand their point. However, when the real LOC happens it is nothing like the SOPs/FCOM say and usually multiple things happen at once. Unlike the simulator there is negative and positive g, manuals, drinks, grit, EFBs flying everywhere about your head - you cannot even read the instruments and the ones that you have trusted for thousands and thousands of hours are not working. The training to reduce risk may have gone through the motions but the visceral reactions to unexpected g, airstream noises, perhaps even shouts screams and bangs from the passenger cabin. This sudden and extreme stress puts you right at the wrong end of the 'inverted U' ( Yerkes?Dodson law - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Yerkes%E2%80%93Dodson_law) ) and leads to cognitive/attentional tunneling usually onto an incorrect area. The training in other words has not prepared the crews for what things could get like. But its difficult and expensive and 'how many of our aircraft will have that problem?' So it is not done. This is unfortunate because as people have said here if you actually _have_ experienced negative g, and recovering from an incipient spin _multiple_ times _and_ been scared a few times then you are likely to perform better. The psychologists call this 'stress inoculation', you are put in the situation and shown how to get out of it. Then when it occurs you are not pushed into cognitive decline by the stress and arousal levels.

The current system is built around avoiding nasty problems around the edges of the flight envelope and training people not to go there. The training is done in comfortable shirt sleeve environments without any physical stresses at all. The training and systems have no doubt increased safety but they have had the unfortunate side effect that when an aircraft is in a sudden upset there is a very much higher chance that the crew will not recover the situation. The very risk avoidance approach has increased the risk of crew poor performance with attentional tunneling due to stress and automation surprise at the very time that they become the sole people capable of recovering the situation.

So now take a many thousand hour fighter pilot and put that pilot in a shiny airliner with two underwing engines and go through all the risk averse training ticking all the boxes. That will NOT include stall or spin recoveries "don't even go there!". Then a few thousand hours into flying the airliner go from bumpy but normal flight in early daylight IMC to all the bells alerts cavalry charges and whistles 2 g zoom climb all inside 20 seconds followed (speculation alert) by a port engine compressor stall as the aircraft approaches apogee with full power on starboard - and the edge of the stall turns into a fast rotation into a flat spin driven by the 'good engine'. Hind brain training kicks in and what were the by rote procedures in the fighter aircraft - and they are implemented. However, the procedures for a fighter with roll/yaw diversion due to a weight concentrated in the fuselage is not quite the same as for a twin jet airliner with a dead engine but that is the practiced response and nobody bothered to erase that response with what to do in _this_ aircraft because we "don't even go there!"

So cautious stay out of trouble training needs to be looked at very carefully. As does the reality of what 'trouble' feels like. If crews felt that once - they may be 'inoculated' against the cognitive stress of its occurrence when it happens.

[formationdriver]

Ian W's post below says it all.


"On the contrary, it is companies that have only been doing avoidance training that has led to the current state.

* Anyone flying manually outside the immediate landing or takeoff gets snitched by FOQA and told to desist: the automatics are better than you are and this avoids the risk of something going wrong.
* If this (alert/instrument fail/behavior) happens then memorize this list of precise instructions and follow them. Get the PNF to read through and check that you have done them and nothing else.
* Sit in this reasonable simulation with critical unrealities every month and improve your by rote response to specific (alert/instrument fail/behavior)

These are all risk avoidance by the aircraft operators. To some extent one can understand their point. However, when the real LOC happens it is nothing like the SOPs/FCOM say and usually multiple things happen at once. Unlike the simulator there is negative and positive g, manuals, drinks, grit, EFBs flying everywhere about your head - you cannot even read the instruments and the ones that you have trusted for thousands and thousands of hours are not working. The training to reduce risk may have gone through the motions but the visceral reactions to unexpected g, airstream noises, perhaps even shouts screams and bangs from the passenger cabin. This sudden and extreme stress puts you right at the wrong end of the 'inverted U' ( Yerkes?Dodson law - Wikipedia, the free encyclopedia ) and leads to cognitive/attentional tunneling usually onto an incorrect area. The training in other words has not prepared the crews for what things could get like. But its difficult and expensive and 'how many of our aircraft will have that problem?' So it is not done. This is unfortunate because as people have said here if you actually _have_ experienced negative g, and recovering from an incipient spin _multiple_ times _and_ been scared a few times then you are likely to perform better. The psychologists call this 'stress inoculation', you are put in the situation and shown how to get out of it. Then when it occurs you are not pushed into cognitive decline by the stress and arousal levels.

The current system is built around avoiding nasty problems around the edges of the flight envelope and training people not to go there. The training is done in comfortable shirt sleeve environments without any physical stresses at all. The training and systems have no doubt increased safety but they have had the unfortunate side effect that when an aircraft is in a sudden upset there is a very much higher chance that the crew will not recover the situation. The very risk avoidance approach has increased the risk of crew poor performance with attentional tunneling due to stress and automation surprise at the very time that they become the sole people capable of recovering the situation.

So now take a many thousand hour fighter pilot and put that pilot in a shiny airliner with two underwing engines and go through all the risk averse training ticking all the boxes. That will NOT include stall or spin recoveries "don't even go there!". Then a few thousand hours into flying the airliner go from bumpy but normal flight in early daylight IMC to all the bells alerts cavalry charges and whistles 2 g zoom climb all inside 20 seconds followed (speculation alert) by a port engine compressor stall as the aircraft approaches apogee with full power on starboard - and the edge of the stall turns into a fast rotation into a flat spin driven by the 'good engine'. Hind brain training kicks in and what were the by rote procedures in the fighter aircraft - and they are implemented. However, the procedures for a fighter with roll/yaw diversion due to a weight concentrated in the fuselage is not quite the same as for a twin jet airliner with a dead engine but that is the practiced response and nobody bothered to erase that response with what to do in _this_ aircraft because we "don't even go there!"

So cautious stay out of trouble training needs to be looked at very carefully. As does the reality of what 'trouble' feels like. If crews felt that once - they may be 'inoculated' against the cognitive stress of its occurrence when it happens."
Ian W is online now Report Post

[rideforever]

"The current system is built around avoiding nasty problems around the edges of the flight envelope and training people not to go there."

Even that gives the current strategy too much credit. It is in fact just about reducing costs and making money. For money-men pilots are an inconvenience to be eliminated as quickly as possible.

Pilots used to be almost worshipped ! The captain of the skies. It was an honour to meet one or visit the cockpit and see those stripes on the shoulder.

Travelling to Asia used to be a once in a lifetime thing, a strange world with strange food and exotic culture. Now busloads go and sit in concrete boxes and etc...

For those in the industry, like in all industries in this age, one must be quite sly to get the best out of it. You must know the money-agenda of the corporations ... no matter what their PR people say in public.

They demand that you robotise your flying behaviour to keep your job ... and yet you may meet a situation where only your skill wits and knowledge is going to save your backside.

If I was a pilot I would certainly be plugging into the simulator all the serious air incidents that affect the models I fly, and going over them until I know exactly what to do to get the best outcome. Without necessarily telling the company what I am doing.

It is interesting if these pilots tried to switch off the computers. It may indicate that they were trying to avert AF447 but hadn't studied the case well enough.

It's one thing talking about life-saving manoeuvres on the internet, but unless you have disciplined yourself to practice them over and over and over again until you are certain, absolutely certain what and why and how ... if you haven't, then if the time comes you will either sit like a rabbit in headlights ... or make a mess of it.

[fireflybob]

They demand that you robotise your flying behaviour to keep your job ... and yet you may meet a situation where only your skill wits and knowledge is going to save your backside.


rideforever, that is so true - one of the best statements I've seen on PPrune for quite a while - thanks!

[whitav8r]

As Ian W stated in his previous reply (excellent insight!), we really have a problem with getting all commercial pilots to train for unexpected upsets to react instinctively - not with primitive brain (which seems to be pull, pull, pull!!).

A simple Google search "loss of control LOC airliner accidents" turned up an interesting article:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20100030600.pdf

that systematically looks at over 100 Loss of Control accidents (they are even listed in the Appendix). We have a serious problem and only radical training can deal with it. When we had Controlled Flight into Terrain as the most serious accident cause, the airline industry spent large sums to deal with it in adding the Enhanced Ground Prox system. Unless we design and incorporate a FlyByWIre Upset Recovery System, we must spend the sums to train our pilots to focus on Push-Power-Roll sequences that will save the aircraft. That same Google search pointed to a company that is already providing the type of upset training that is required -
Upset Recovery Instruction, Aerobatics Flying, Spin/Stall Flight Training (http://apstraining.com/) - take a look!

[IcePack]

Hope they know what they are teaching. Aerobatic aircraft techniques will have the tail separating from a big jet.

[Sop_Monkey]

IcePack

I dont think aerobatics a large passenger aircraft would be in the syllabus somehow.

I would think they try and teach the recognition and the best way to recover from usual attitudes, by putting the least amount of G on any aircraft.

[IcePack]

Hope so, but the way some talk on this thread the mind boggles.

[SLFandProud]

Even that gives the current strategy too much credit. It is in fact just about reducing costs and making money. For money-men pilots are an inconvenience to be eliminated as quickly as possible.

Pilots used to be almost worshipped ! The captain of the skies. It was an honour to meet one or visit the cockpit and see those stripes on the shoulder.

And yet... Flying now is indisputably safer than when pilots were 'worshipped'. Would you like a few more deaths from avoidable accidents just so the self loading freight down the back could be reminded just how much respect they need to show the pilot? Maybe the odd manufactured 'emergency' to remind them how grateful they should be to the gods of the skies? Yep, turn off the automatics and lets get back to it being a man's game, where there are no old bold pilots but by God the passengers went down screaming the captain's name out of respect rather than terror when he screwed up and killed them all.

When deciding that is the case, perhaps you should also ask the surgeon the next time you go into hospital if he wouldn't relive the glory days by operating on you half cut with a fag in his mouth and without using any modern machines. After all, medical personnel also used to be gods - back in the days when many more people died on operating tables.

Taking the train was much more adventurous back in the day as well of course, before automatic train protection systems and all that bloody technology came in to stop every boy dreaming of being a train driver. OK, so a few people died, but hey the driver was having more fun and that's what's important right? Turn off the TPWS and lets have the oil lamps and semaphores back.

I'm afraid it's happened to every industry. It's called maturing. The first few people are pioneers, who succeed on luck as much judgement. That doesn't last, and eventually professional standards take hold, and the old guard moan that it was more fun when the odd ****up (even if fatal) was a risk it was acceptable to take. Plus ca change. The only difference is that pilots got the god-complex bug even more than most.

Travelling to Asia used to be a once in a lifetime thing, a strange world with strange food and exotic culture. Now busloads go and sit in concrete boxes and etc...

And you see that as a bad thing do you? All those bloody peasants, being allowed to travel! Don't they know aviation is only for the elite, for heavens' sake?!

[Capn Bloggs]

Flying now is indisputably safer than when pilots were 'worshipped'.
We do have a chip on our shoulder, don't we? The main reason that flying safety has increased is because of things like TCAS, EGPWS and FMS based approaches. It's got almost nothing to do with the lessening of the macho heros. In fact, you're very lucky flying was as safe as it was in the old days; only because of the skill of the pilots. Now that the beancounters, aided and abetted by the regulatory authorities, have diminished pilot's flying skills by reducing/eliminating SIM practice time to compensate for reducing on-the-line hand flying, we are seeing a rise in the number of LOC accidents. So how about giving the pilot/doctor-bashing a break?

pointed to a company that is already providing the type of upset training that is required -
This could easily be achieved in our current Sims. There just needs to be the will.

[md80fanatic]

I'm afraid it's happened to every industry. It's called maturing. The first few people are pioneers, who succeed on luck as much judgement. That doesn't last, and eventually professional standards take hold, and the old guard moan that it was more fun when the odd ****up (even if fatal) was a risk it was acceptable to take.

If modern professional standards equates to monitoring automatics until such a time when the automatics give up, leaving two out-of-the-loop beating hearts to question what is wrong and fix it before landfall ... I prefer the sky gods, thank you.

[RatherBeFlying]

I was disappointed back in AF447 that an A330 was not flown through the initial zoom and stall profile, perhaps with spin chute.

The data could have been provided to the sim manufacturers so the crews would have an opportunity to explore high altitude stalls and recovery with valid data. This crew, their passengers and their families might have benefited.

There is talk that no crew should ever get near that edge of the envelope, but convective activity can put any crew in a place they never intended to be.

Until the data is available, the ITCZ crapshoot will continue.

[Right Engine]

SLFandProud. Your analogies are superb....But you shouldn't be sidetracked by the occasional retired 'Skygod' sitting at their computer, tapping away feverishly at their keyboards about how brilliant they were in the 80's!

The problem is that ordinary pilots believe that the direction cockpit design took as technology 'enabled' enhanced safety, was to an extent the wrong one.
To remove the human input from cockpit automation, to dismiss ergonomics and human-machine interface design so comprehensively.

Things will always go wrong environmentally. It's called bad weather. It will always outfox a drone pilot or the most sophisticated automation technology. But when an Airbus has the equivalent of a 'kernel exception error' because it's probes have frozen up or it's Angle of Attack probes are jammed, it takes a pilot to know beyond the rudimentary basics of flight using only rudimentary instruments that remain. That requires training and that costs money.

This is not about ego. We all want 100% safety. It just requires making pilots more skilful to achieve that aim. Don't confuse those who moan about that lack of training as Egotistical!

[SLFandProud]

SLFandProud. Your analogies are superb....But you shouldn't be sidetracked by the occasional retired 'Skygod' sitting at their computer, tapping away feverishly at their keyboards about how brilliant they were in the 80's!
Oh absolutely, I quite agree; the point I was trying to make is that this is a completely normal and natural evolution, and as depressing as it may be if you were once a 'sky god' there's no point tilting at that particular windmill.

It happens in /every/ industry.

Hell, the software engineers of my generation will moan that the job was more skilled when we hand rolled assembly language using nothing but a HEX editor, and that all this modern nonsense like automatic garbage collection and strict type checking means that any old Tom, Dick or Harry could write code with all the skill taken out of it.

Would you rather the automatics on your plane were being programmed by the greybeards like me who insist on using stone and chisels or with the full aid of all the modern compiler and software correctness tools available?

The problem is that ordinary pilots believe that the direction cockpit design took as technology 'enabled' enhanced safety, was to an extent the wrong one.
To remove the human input from cockpit automation, to dismiss ergonomics and human-machine interface design so comprehensively.
And that is an entirely valid argument to have. But it's not the one that @rideforever was making.

This is not about ego. We all want 100% safety. It just requires making pilots more skilful to achieve that aim. Don't confuse those who moan about that lack of training as Egotistical!

I think it's fair to say when @rideforever starts bemoaning the fact that pilots aren't worshipped any more it's hard to see it as anything other than an appeal to ego.

Look, I totally agree with your point. I learned to fly gliders long ago, stall recovery was in literally the first couple of lessons and was drummed in hard, so I find it absolutely astonishing that the pilot of AF447 could pull back on the stick all the way into the sea. But the blathering about automatics and sky gods seems to me to be to deflect the subject from inadequate training, not to highlight that that really is the problem. It's not the automatics making pilots incompetent - it may be the automatics meaning that incompetent pilots get to fly for longer before they kill themselves or their passengers, though.

As a society, we make even decide that's an acceptable tradeoff, since the overall levels of safety have absolutely increased, and since it has also resulted in the poor folk that @rideforever so derides to have access to travel that they could only have dreamed of not so long ago.


(As an aside, I also love the fact that because there was an Airbus involved everyone has basically assumed the entire incident is identical to AF447 and all the same arguments can be rehearsed, despite there being absolutely no evidence I've seen to support the assertion whatsoever.)

[VR-HFX]

I am a simple old world kind of person who has managed to stay alive after 10 years in the military and 30 years in civil aviation. I have had to learn to adapt to the fact that the machine knows better than the man. But does that logic follow when parts of the machine are compromised and parts are not? Indeed when parts are compromised, it is possible that the remaining parts are working against you rather than for you, but you are in such a lather that you don't or can't read the message.

Having trawled the various airbus accidents, I am convinced that there is a very serious problem with the trim control in partial degradation of systems. The Perpignon A320 accident is a classic example.

Small print advice is not something one can understand in a major upset.

Please Mr Airbus...do something about a system that will allow trim to work against a pilot in the case of partial or substantial upset.

[Centaurus]

A few years ago in the simulator I was required to upgrade an experienced B737 first officer from RH seat to LH seat. This was in the days when the Australian CAA licencing system has first class endorsements and second class endorsements. First class endorsements were for captains and first officers were given second class endorsements. As expected back then, the second class endorsement was not recognised outside of Australia and that meant some pilots could not get jobs overseas despite being highly experienced.

This particular pilot had no problem whatsoever operating from the LH seat. At the end of the endorsement training we had time to spare and I asked him if he would like to practice some unusual attitude recoveries in IMC. He thought about it for a moment before saying he thought UA's were a bit of a waste of time. Anyway, he reluctantly gave it a go. The simulator was set up for a un-commanded steep pitch up at 500 ft agl after take off. Airspeed loss is dramatic. This had really happened some years previously in USA and by superb handling the USA pilot had rolled sharply through 60 degrees to get the nose to drop and cleared a building by 100 feet in the recovery.

In the event, our pilot in the simulator was completely caught by surprise when it happened at 500 ft in the simulator as he expected the UA's to be done at 10,000ft. He tried forward elevator to stop the immediate speed loss but to no avail. With the nose going through 50 degrees nose up, he made no attempt to roll to the nearest horizon to get the nose to drop which would have saved the day. To my astonishment, he pulled both engines to idle and the simulator gave up the ghost and fell out of the sky.

In short and despite several thousands of copilot hours on automatic pilot on the 737, he simply didn't have a clue. Certainly he was unfamiliar with the pertinent chapter in the FCTM about UA recovery technique.

I suggested he have another attempt - this time rolling to the nearest horizon. I even offered to slip into his seat and demonstrate the recovery technique. He looked at his watch and reiterated he thought UA's were a waste of valuable simulator time and that in any case he had an appointment elsewhere. In other words he had stuffed up big time and refused to admit it.

This episode proved to me that automation dependency will continue to be the shadowy danger in the flying of jet transports. It beats me that time and again we see regulators and ops management paying lip service to manual handling skills but have yet to schedule comprehensive simulator training to mitigate autopilot dependency. One well known Middle East carrier boasted that they had added one extra hour per year of manual handling. What a laugh that was. In other words extra safety measures that involve simulator training are seen as a unnecessary cost impost.

The occasional raw data ILS to tick a regulatory box is virtually a waste of time as it does not scratch the surface in terms of manual handling. I believe we will see more future instances of loss of control in IMC as pilots are forced into more and more automation by their ops management.

So much valuable simulator time is wasted on button pushing and excessive check list reading exercises. In turn, this must only increase automation dependency. IMHO, to counteract ever-increasing automation dependency, 50 percent of all simulator training should be devoted to non-automatics handling in IMC - and that includes high altitude flying. High altitude stall recovery skills (37,000 ft) and landing configuration stall recovery skills (1000 feet AGL) are vital.

[yadot]

Centaurus,




I would like to say that what you wrote is one of the most important and well articulated pieces that I have seen on this site for a while. Thank you for illustrating and sharing your insight.


Largely due to financial pressures of the industry, finding the balance between training costs and associated risk of crew experience is important of course. In the case of these airlines that have lost aircraft, the cost and pain for all involved has not been measured well.


The over reliance on automation is fact and needs to be addressed in a cost effective approach.


I have done research on this area and at times I feel safer in raw data at the 'what the' moments.




The high stall recovery techniques at FL510 are interesting.

[Ian W]

Oh absolutely, I quite agree; the point I was trying to make is that this is a completely normal and natural evolution, and as depressing as it may be if you were once a 'sky god' there's no point tilting at that particular windmill.

It happens in /every/ industry.

Hell, the software engineers of my generation will moan that the job was more skilled when we hand rolled assembly language using nothing but a HEX editor, and that all this modern nonsense like automatic garbage collection and strict type checking means that any old Tom, Dick or Harry could write code with all the skill taken out of it.


Your analogy does not hold for aviation.

As a software engineer you will know that there are always going to be difficult areas - the 'otherwise cases' that drop through the IF-THEN-ELSE logic or the places where the analysts and designers cannot come up with a simple fix as the number of potential permutations in the real world make a simple solution difficult. In the FMC and Autopilot software the way out of those nP problem areas has been for those systems to failover to the human pilot handing them the bag-of-bolts and expecting them to recover the situation that the automation could not.What you are saying is true that many areas of work have had automation creep in and deskill the operator. But aviation is unlike those as people will die if the automation goes wrong and the software analysts, designers and implementers have ducked the final responsibility when it gets difficult and handed it to the pilots. You know the 'sky gods' you keep running down. Because management in their ignorance treats automation as fault free they are paying off the 'sky gods' and replacing them with systems managers. So they are in the process of removing the final safety stop that the software analysts, designers and implementers always assumed would be there to save the day. In other words management and the software analysts, designers and implementers have worked together to create a system that fails dangerous rather than fails safe. Indeed short sighted attempts at graceful degradation have actually made the failure cases far more difficult for the human to take over as the actual state of the automatics can be indeterminate - but they cannot be switched off.

So the systems builders expect a 'skilled sky god' to save the day when they find it too difficult to build automation to cope and their system fails. Their systems do not fail in a simple way but sometimes in unexpected and complex ways compounding the original problems and management, trusting the system providers who say how very safe their systems are start deskilling the pilots so there are no 'sky gods' available in the cockpit to pick up the bag of bolts.

This potential problem was foreseen long long ago. One of two things will have to happen, the systems builders clean up their act and build 100% fault tolerant systems that can cope with multiple sensor failures and never lose control and automate the pilot completely. This may happen sometime but on current showings the systems builders are not yet clever enough and couldn't afford the insurance. Or the industry starts ensuring the pilots can actually pick up the pieces WHEN the systems fail. This means very limited training in the routine and very intensive and extensive training in systems faults and LOC including live manual flying and LOC training.

I get the impression that at the moment heads are firmly in the sand they will need to be extracted.

[tommoutrie]

Centaurus

I'd like to add that I'm in the sim next week - thanks for giving my sim bloke a brilliant new plan to mess my world up...

[captplaystation]

Better at least to be messed up in the virtual world than the real . . . . . back in the day, there always seemed to be a bit of time left at the end to "try things". These days, unfortunately, the box- ticking seems to take up pretty much every session, shame, a bit of "out of the box" stuff was always valuable / eye-opening. :eek: