john_tullamarine

AF 447 Thread No. 6

Thread part -

(a) #1 starts here and finishes here. Posts = 3890
(b) #2 starts here and finishes here. Posts = 2537
(c) #3 starts here and finishes here. Posts = 2071
(d) #4 starts here and finishes here. Posts = 1061
(e) #5 starts here and finishes here. Posts = 1978


Links to the various BEA reports are given below. If I have missed any of the useful papers, please PM me with the URL and I can include it.

(a) BEA site - French, English
- Report link page - French, English

(b) Interim Report (No, 1) Jul 2, 2009 - English

(b) Interim Report No. 2 Dec 17, 2009 - English
- Update Dec 17, 2009 - French, English

(c) Estimating the wreckage location Jun 30, 2010

(d) Wreckage search analysis Jan 20, 2011

(e) Briefing and associated update May 27, 2011
- Briefing - update French
- Briefing - update English
- Briefing - update German
- Briefing - update Portugese

(f) Interim Report No. 3 July 2011 - French, English

Miscellaneous pertinent links -

(a) Airbus Operations Golden Rules
(b) ALPA FBW Primer
(c) C* and Civil Transports - Cranfield
(d) Longitudinal Flight Control Design - RAeS
(e) Longitudinal Stability: Effect of High Altitude and CG - Boeing
(f) pitot static system performance - USN (Pax River) FTM

Search hint: You can search PPRuNe threads with a filter in Google by using the following search string example -

ths af447 site:http://www.pprune.org/tech-log/

This will search for mentions of THS in the AF447 threads of tech log only.

Just change the THS in the string to whatever you want to look for. This allows one to search for any term or phrase of interest throughout the threads.

Adding the site:URL end part is the magic that restricts Google to only searching in Tech Log.

This filter technique is absolutely wonderful and can be used generically to find things of interest in PPRuNe - appears to work OK in the PPRuNe search function as well.

Graybeard

Wow, the first to post on this thread...

I get the feeling the Airbus 320+ was designed for single pilot operation from the beginning.

Zorin_75

Just a remark on the last post of thread #5 -
Predator Drones are of course flown by pilots, here's the "flight deck":
Image Viewer images/stories/full-size/uas_15-110712-02.jpg – TechNewsDaily
It just happens to be not on the aicraft.

Lyman

takata re: SPIKES.

The Airbus has this elegant escape from CFIT? NON?

Max power, roll full, and pull back max.

A max effort, 'at the limits' safety manuever. During which the a/c nibbles at Stall? and wing drop? No sweat, the Bus knows SPIKES.

The Pilot doesn't. As above, for Alternate Law, the STALL WARNING needs some looking into.

HarryMann

Fair enough HeavyMetallist, I didn't make a very good job of saying that it just isn't always possible to avoid the stall... we've had two or more in A-Buses fairly recently. And note too, this aircraft configuration seems to have fairly benign stall characteristics, stays pretty straight - waggles its wings a bit - but doesn't appear to spin or nod seriously. Likewise, from the Turkish Amsterdam experience, that 737 seemed to mush straight in, and was close to a recovery should some more height have been available.
Note! Both to some extent auto-trimming + inattention accidents.

But please don't think you'll ever avoid stalls 100% - that theory has been proved wrong since the Wrights. In fact, may well have helped cause this accident..
So.. at least... let us talk seriously about educating pilots about what stalls [really] are, not to be so scared stiff of them that they yank the stick back and open up the gas every time the very idea enters their head rather than a firm & steady ND, which has always been the No. 1 lifesaver! (which rarely will do any harm, speed is safety, even near the ground it can be fairly readily re-converted to PE!)



I know they're not stupid ... I worked alongside some of them for years. But yes, again, was over the top in trying to make the point that the instrumentation aspects of this accident are not simply (and only) about icing pitots. Many assumptions that were made at original design time have to be re-assessed.. The whole thinking behind some of the most important basic instruments should be looked at again... it can very often be the 'off-design' case that suddenly become 'on-design' to catch you out. Here we have ASI basic (heating icing venting) pitot problem, ASI high alpha position error uncertainty, compunded by an AoA vane that really should be 99.99% foolproof and not reliant on an ASI cutoff, nor prone to any weather related problems itself and from Perpiganan - a lot more robust in basic nature.

Better backups should, indeed must, be de rigeour and not 'optional extras', ne'st pas.. these are civil airliners carrying many hundreds of passengers... lets just thank our lucky stars that many more have not dies in the last few decades from glaring faults that have caused many tens of extremely serious in-flight incidents.. every one a serious accident or a/c loss in the making.

and again, come back from the precipice of l/h and r/h sidesticks. They are NOT a good ergonomic solution

Clandestino

It's type specific. First time I stall my current aeroplane, remaining lifespan of my passengers, my crew and me will be measured in seconds. 200 is very best we can hope for or perhaps it would be: the shorter, the better. I can understand the irresistible temptation to indulge in aeronautical generalizations based on single or few cases as I'll be first to admit it's boring, very uncool and perhaps even a bit frightening to rationally debate positively lethal stall characteristics of some T-tailed turboprop regionals and ways of dealing with them. Here we have real-life-case-study of heavy jet that even didn't spin at extreme AoA so we can indulge in heavily romantic notions such as: "they could have recovered it if: computers let them, they had yokes, stall warning didn't stop, they didn't fly into the storm (they didn't anyway), protections were working, it wasn't Airbus" or whatever half-informed mind would come up with.

Personally I find them acceptable. I have flown yokes with right and left hand, centrally mounted stick with right and left hand, sidestick with right hand, didn't find anything difficult or unacceptable about any of them and loved to handfly any aeroplane I was given at the time. A320 was by far nicest and easiest transport aeroplane I've flown though to be fair, I must add that it is also the only jet I'm rated on. She was docile even in direct law although I haven't experienced it outside the sim and I've come across only one pilot who got it on line (dual radalt fault). He claims it was even easier than sim and knowing him, I'll take his word for it.

It would seem that Airbus, Lockheed Martin (ex General Dynamics), Dassault, Sukhoi OKB and Cirrus are not believers in ergonomical unacceptability of sidestick.

PuraVidaTransport

I've made my views clear I think the primary cause of this accident is the Air France training/hiring/promotion practices however, I find myself thinking of some other things as well. The engineering of the aircraft, placement of probes and such is without doubt very good (and I am a Boeing fan). In almost all cases, things will work as they should and even (most) did in this case.
I do see valid points with the sidestick vs. yoke argument. I see a lot of times in the CVR/FDR data where the yokes may have made a difference. I think the yoke would have even more explicitly told the PNF just how badly the PF was 'over-correcting' for small deviations and he might have put some 'gentle pressure' on the yolk to smooth things out a bit. PNF had the experience, the seniority and the hours in the airplane but not the authority it seemed. With a yolk, 'sending a message' might have been easier through feel than verbally as he tried to several times unsuccessfully.
If this accident happened even in that case, we may have seen traces more similar to Egypt Air depending on how far the pilots were willing to push what they thought was happening. Looking at the last few seconds of the traces, strangely similar to Egypt Air and I'm sure this was due to confusion and two pilots not trained in how to react and their responsibilities in a crisis and a captain's poor decision to leave the authority in less skilled hands.
I don't see the yoke vs. sidestick being an issue except in crew teamwork. With good training, it seems to have been proven either is a safe and effective way to handle an aircraft. However, in those crisis times when two guys have to work as a team, the sidestick may not be the best solution.
Then again, what would have happened in the Egypt Air case had it been an A330? The computer would have summed the inputs and they would have had level flight, once they got the engines restarted obviously?

Mr Optimistic

There's an awfully long discussion going on about this but (as an SLF) would a real pilot please explain how you could sit for minutes with a nose high attitude, good power from the engines, a descent at 10000+ ft/min and not at the very least suspect - or admit as an option - you were stalled. As it clearly did happen it seems to me that the complexity and general protections offered by the aircraft in normal operations are such that they (and the training) have distorted the mental perceptions and outlook to the extent that physical realities have been exstinguished.

HarryMann

OK, lets not confuse the issue with military references, I'm not silly enough to suggest that a sidestick is not the solution at high lateral and vertical 'g' loads in a confined space. It's also rather ignoring the fundamental of left & right propensity, since there'd only be one in amil a/c and whichever it was, you'd get used to it...

Ever tried hoola hooping ?

Which is your 'normal' direction - clock or anti-clock ?

Are you as good at it clockwise as anticlockwise, can you keep it up both ways ?

Unlikely, and what you are comfortable with, definitely helps in an emergency - one of the few times you'll be manual flying at altitude soon.. an emergency.


The Cirrus stick looks like you could almost use either hand - an interesting half way house?


I am very sure that the s/s, whilst it may (should) be mentioned in the final BEA report as a contributing factor (in the confusion at least, if not in possible overcontrol and climb (UP) fixation)... will never be condemned nor changed in ABs

.. because very much on the whole, it is satisfactory for the purpose intended and the vast majority of AB pilots are used to it, proficient with it and would not let it affect their flight control, whether left or right seat.

All this is not the same as saying that its innate ergonomics and possible l/r positioning for PF (and/or PNF) did not come into the safe conduct of flight after 2:10:00 for AF447 - because very clearly, in this instance, it did!

Shutting eyes to any facet involved in such a serious aircraft accident is never a good idea... whether 2,500 other aircraft have that facet or not... or even 250,000 others.

hetfield

These poor guys put the sidestick

NU - no stall warning
ND - stall warning

For me it's like a nightmare.

"What would I have done in this situation ?"

The more I think about it, the more I feel angry about this poor design and totally sorry for all the lifes it took.

rudderrudderrat

Hi HarryMann,

Some interesting points raised there. It seems a shame that the AB cockpit is designed around mostly visual and auditory clues.

The pilot is deprived of sensory feed back from the other pilot's SS inputs, elevator displacement load due autotrim (and by Elevator Displacement by FCCs) and Thrust Lever position when autothrust is engaged.

When it the automatics dropped out during UAS, Manual Thrust was required with no "muscle memory" of where the TLs should have been before, and there is no elevator load feed back due FCCs. Roll is direct and much more rapid than it was in Normal Law.

Why can't the AP simply hold "ATT" like we used to have with CWS (control wheel steering) 40 years ago? It would have freed up a few more brain cells.

JD-EE

Hardly - fully autonomous aircraft are not fit, yet, to handle combat landing for a C130 or some aspects of air superiority work.

Those are the roles I had specifically in mind with that post. Taking pictures and dropping bombs when in a complete air superiority situation is relatively easy. How many UAVs or AAVs get plinked from the ground?

JD-EE

Zorin 75, some fully autonomous drones are appearing. Their only level of non-autonomy are the high level instructions - go to (location), circle it at some radius at some altitude, take pictures, send back interesting looking pictures. The chain of instructions can include a series of way stops for pictures and other uses. Nobody's "flying" it with a wheel or joystick. It's more typewriter driven and handles all the details of avigation itself. This hit the news fairly recently - amidst some apocalyptic rhetoric and reference to the Terminator films.

bubbers44

I think hand flying using those brain cells and knowing how to do it would have prevented the whole fiasco. 3 degrees nose up, 85% N1 would be a good start.

Owain Glyndwr

RRT

Forgive me, but isn't that exactly what the Alternate law does if left alone to fly the aeroplane?

Quote:

So how does an airplane with a pitch-rate command or g command fly? Essentially, it

rudderrudderrat

Hi Owain,
I'm afraid not.
In ALT LAW, Pitch remains stable provided there is no ss input, but roll is direct and will constantly need an input until the aircraft is trimmed correctly. It seemed to give the PF loads of work because he hadn't practiced the technique sufficiently.

The only place to practice would be the simulator (twice a year normally - Unless he had UAS of course)

Owain Glyndwr

OK - I had pitch in mind not roll - I fully accept the difference.

Lyman

So in AL2, the Pilot is presented with different 'feel' in two axes?

The a/c is a package, and given the PF has made some fundamental mistakes, should one additional challenge be DIRECT in Roll, and not in PITCH? The Rudder needed to be a 'suggestion' from Captain?

You know, the fundamental flaw here may have been a clumsy catch from Auto. That is not difficult to understand in Simulator? The cost per pilot, five minutes in a 45 minute syllabus? Twice a year? A Grand?

Diagnostic

Hi rudderrudderrat,
Or unless there is turbulance - true?

It seems to me that the PF had to make some roll inputs immediately after the AP disconnected, due to the turbulance (page 74, English version), and the (mainly NU) pitch inputs which led to the stall, were inadvertent and unintentional (e.g. perhaps muscular tension (not unexpected due to the "surprise factor"), and/or seat adjustment, and/or l/h vs. r/h seat usage, or other unknowns etc. as has been mentioned here before).

My point is that without having an "H-gate" arrangement (like a manual car gearstick) on a sidestick or control column - which I'm not advocating, of course - then it's impossible to only make inputs which are only in either roll or pitch. There will always be an amount (hopefully very small) of cross-coupling between inputs in those two dimensions (at least in my experience) especially when there is turbulance.

In other words, a design which requires roll inputs, is going to get some pitch inputs, like it or not, with a normal pilot - add in the surprise factor, turbulance, lack of high alt hand-flying training etc. etc. and this can all add to the amplitude of the pitch inputs, which seem to have been unrecognised by the PF, and the lack of recognition then caused the long duration of that NU input (which, integrated over time, drove the THS movement).

Can we ever expect a total lack of any pitch input, when there must be roll input, during conditions such as those? I'm uneasy (as a non-expert) with adding yet more automation into a situation like this, where the automation can "give up", but I can't believe there isn't a better way than dumping roll and pitch control onto a surprised pilot at FL350, at night, in some turbulance.

Interesting, the AB design seems to recognise a sort of "keep things as they were" philosophy (not unlike the UAS procedure, when above MSA) regarding the throttle at the point when the AP disconnected, since throttle lock occurs (until deliberate manual control of the throttles is commanded).

If that is appropriate for the throttle (and it seems to me that it is appropriate, for the short term immediately after an event like AP disconnect), why not also for the pitch control (again, until there is a deliberate decision from the pilot to takeover that function, which must not then be trained for pilots as an immediate reaction)? That would give some time for the PF to "catch up" with what is happening, rather than force him/her to takeover more than roll inputs initially... Just a thought.

[Edited to add: Of course that sort of "pitch lock" idea, would have to mean "with neutral elevators". Perhaps this isn't such a great idea, but I just don't believe that we can expect a total lack of unintentional pitch input, when there must be roll input, and with all the other factors that were against them...]

[Edited again to add: When you said earlier:

Is that the same as having an initial "pitch lock" (until deliberately overridden, when the PF has "caught up") which I've been trying to describe (badly)?]

3holelover

I don't believe that to be the case. The stick's neutral position, in both axes, is fairly certain... it's rather easily maintained in that 'detent' - if you will - of one axis while being moved within the other.