744 Forum

This news article updates the information on the still somewhat mysterious crash of the Air France airliner into the Atlantic during cruise.

https://www.nytimes.com/2011/07/30/world/europe/air-france-flight-447-crash-report-july-2011.html?ref=todayspaper

Is an always-displayed angle-of-attack indicator essential for an airliner as this story suggests?

Personal opinions only.

I doubt that an AoA indicator would have helped these people. Apparently they got tricked into "everything except a stall" thinking. It is too easy to dismiss "strange" instrument readings as "failed" when you face such a situation (with air speed already gone). AoA indicators can freeze over as well.

Keeping the nose up as far as possible, but without stalling is what a fly by wire system does when it is 100% operational and in "normal law". By pulling the stick aft, you tell the plane to look for the edge of stalling, and maximize lift within the current environment. However, the plane was not in this normal law any longer, it had been kicked out of this when the computers noticed that they did not receive reliable airspeed info. Therefore, the plane could enter a stall if asked to do so. And unfortunately, the man at the helm seemed to have missed this essential mode change to "alternate law". He flew right into a stall, apparently while assuming that his control input would go to max lift, but never stall.

To my unprofessional mind, it would have been better to have much better indications of leaving normal law and entering alternate law, than having an AoA indicator. The PFD wasn't lying. A synapse in the pilot's brain was being ignored. When you operate a machine out of its designed envelope, it won't work as you expect. First get it back into envelope, then try to fly it.

Very sad, as this wasn't just a personal error by an inexperienced pilot. And too easy to analyse it from the comfort of my computer keyboard with a fresh coffee.


Jeroen

http://www.airbusdriver.net/airbus_fltlaws.htm

Jeroen Hoppenbrouwers wrote

And unfortunately, the man at the helm seemed to have missed this essential mode change to "alternate law".

Also strictly personal observations. I agree with Jeroen that the essential thing here may turn out to be the human factors-warning system loop. Reading the preliminary report a couple of months ago, I noted that the only mention of the AoA law shift was another crew member's call-out that they were now in 'alternate law' mode - easy to miss in the stress and confusion as Jeroen notes. I would naively think that a system that is designed this way ought to also give you bells, horns, 'Caution! Caution!' messages or something when you lose essential AoA protection, and not rely on a non-standard checklist item (maybe Airbus has such and it wasn't mentioned?).

Interestingly enough, although I haven't studied it in great detail, the proper understanding of the AoA law when operating normally may have been a critical factor in helping Sollenberger land intact in the Hudson. My understanding is that while trying to set up the ditching conditions, he could just keep the stick back and trust the system to give maximum lift and not to stall, while concentrating on other items.

All in all a tragic reminder that even the best systems and pilots can fail. Hopefully some useful lessons will be learned.

Regards,
Torrence

Hudson landing: for sure, this helped them a lot, and they knew it. I even assume that Sullenberger was keeping a close eye on whether he still had the normal law available, knowing that when it dropped due to lack of systems, he had to trade altitude for speed to stay safe.

I remember that some people fundamentally object against mode shifts in critical systems. In this particular FBW case, it means that the alpha floor and pitch protections should never be active, as they will at a certain moment (rightfully) drop off, leaving the pilots with a fundamentally different aircraft to fly. Quite a choice to make: protections that work properly and add to safety in many cases, yet very once in a while cause just that extra bit of confusion and turn salvageable upsets into tragedy.


Jeroen

I have written here and elswhere miles of text about cockpit design in general and Airbus in particular, both related and unrelated to this unfortunate aviation catastrophy. I agree essentially with Jeroen:
a. A human can only absorb, evaluate and respond to a limited amount of information per unit time. The integrated display system presents efficient, but abundant information which slows down pilot reaction, and in not-so-extreme situations may cause non-response with serious consequence. I had mentioned here NASA/ Boeing information before. In this respect, to automatically vary flight control laws as systems degrade is suicidal IMO.
b. The human flying an automated aircraft doesn't get nowadays enough hands-on flight training, for the "sake" of savings, as dictated by pencil pushers.
c. If you take a PPL graduate, through quick turbo-prop regional airline tour, and put him at 43,000 feet and mach .85, he's got no preparation for that and wouldn't know what to do there manually when needed, AF447 is proof. On the other extreme, the Hudson captain had preparation which made everything natural for him to control a very difficult situation very well.
d. This leads to my point about selection of psych-motoric, cognitive properties together with appropriate character, just add proper background training, which PPL and t-prop do insufficiently.

The AF447 fate was written on the wall, contribuited by aircraft design, pilot selection and training.

Even from a poor pilot, I expect to read 11,000 FPM altitude loss, no airspeed, with nose up as stall, and recover from it quickly, or he has no business entering cockpits. I also expect from pilots, even in difficult times, to walk away from unsafe companies. One can load trains with cargo to support his family, better than becoming fish feed.

If I may add:
Co-Pilot #1: 37, with more than 6,500 hours of experience, 4,500 of them on A330s; Co-Pilot #2: 32, with under 3,000 hours of experience.

These pilots fly between 600-800hrs per year, two/three simulator sessions per year, get a technical training day each day, emergency training (e.g. slidetraining) a day each year, CRM training each year.
We're talking about 8-11 years experience for pilot #1 and #2 about 4-6 years of experience, flying 5-3 or 6-3 maybe schedules (5 work days, 3 off, day in day out, all year long).

EU-OPS requires the operator to train all aspects of the aircraft, I'm not a regulation expert, but we do a 3-year cycle (I believe the local authorities demands this), that means we train ALL aspects of the aircraft within every 3-years. For example this year is all about stalls, electrical systems, hydraulic systems and flying into known icing conditions. I say for example.
Which means I don't train the stall for 2 years, in year 3 we train all kind of stalls, electrical problems and hydraulically failures. That is ON TOP of all EU-OPS requirements for keeping the license valid (proficiency check): engine failure before V1, after V1, single engine go around, precision/non-precision approaches with N-0/N-1 etc. etc. (there is a list on the internet). All spread over 3 simulator sessions a year, 3x 3,5 hours in the simulator, briefing before, debriefing thereafter. We're not talking about a flight from a > b, but about 6-10 take-off/landings per 3,5hr. With all kind of (multiple) failures.

You can assume that these companies (e.g. AirFrance) have a so called 'Just Culture':
A 'Just Culture' is a system that acknowledges the unintentional nature of human error and seeks to learn from mistakes. This will encourage personnel to report an error and participate in its investigation without fear of disciplinary action. This includes trend information gathered from FDM (Flight Data Monitoring) system: a 'devil' box which records if you did something stupid e.g. taxi too fast, but also gear-down too late, unstabilized approaches, overrotate etc. etc. thousands of parameters are recorded and weekly sent to an independent company which anonymizes the data and they provide us the trend information.
If we really crossed the line we get a call or a letter from the flight safety officer and have to report to him, normally without consequences, unless we did something really stupid. Learn from mistakes.

We discuss these outcomes in groupform, takes about 1/2 day per year, plus we get a monthly safety magazine which discusses world wide incidents and accidents.

I sincerely cannot believe nor accept the fact these pilots were somehow inexperienced or incapable of handling this problem. Yet it did happen...
Calling the captain and discuss the problem, within 3-3,5mins: impossible. These 3mins (38000ft/11000ft/min) are gone within the blink of an eye. Not to mention the uncomfortable or maybe even painful rapid pressure change in the cabin during descent.

Just my two cents.

We sometimes discuss this 'strange' incident in the cockpit: both of us experience shivers down the spine...

As flight academy commander I was in charge of both syllabus composition based on organization requirements definition, and flight proficiency checks to every kind of student and instructor. As long as you maintain the standards of selection which I wrote about, level of instruction, education and upbringing of the young, you get excellent excellent results. For the right human is creative and full of imagination, and can cope well with the unforseen, even in dire circumstances.
Now I need to understand why an aft sidestick controller input was maintained through this vertical descent??

With all due respect to organizational culture and substantial flight and type experience, the end result fails to reflect them. And all they exist for is the end result.

Its a little low level, but contains some transscripts
of the voice-recorder:

http://news.yahoo.com/pilots-wrestled-vain-save-air-france-jet-024238152.html

Zinger wrote

Now I need to understand why an aft sidestick controller input was maintained through this vertical descent??

That IS what frightens me, something happened that got them locked in this situation. The question is what got them locked into thinking the A/C was not stalling. I mean: <exaggerate mode> don't have to tell you that during basic flying you stall more than you train landings . Reading the latest report: the aircraft was pitching and rolling (40degrees pitch and roll) violently, making troubleshooting more difficult. Speed bumping up and down from 275 (M.8 at given alt) to 60kt and back. It's not just a matter of a perfect clean stall situation where common sense takes over.
Again 4 minutes till impact is a dramatic short period of time: no room to discuss the situation really.

Zinger wrote

With all due respect to organizational culture and substantial flight and type experience, the end result fails to reflect them. And all they exist for is the end result.

I wanted to emphasize the amount of experience these guys have. It's not only flying from a > b all day. There is a lot of training involved during daily operation. And of course co-pilots are often defined as the ones with the least experience, which in Europe is definitely NOT true. With all due respect to the AF447 crew: due to seniority or company rules it IS very possible to have far more experience on type as co-pilot than the captain has. Papers over here writing 'The captain was NOT in the cockpit!', emphasizing the ultimate-man-who-saves-the-day, is being laughed at, literally. Not this particular captain of course, but generally speaking.

I'm sorry if I'm 'trolling' or whatever, that is absolutely not what I had in mind. Just want to explain there was more involved than a 'clean stall situation and pitching the nose up'. I doubt if a AoA indicator would have helped here, difficult to read during violent attitude changes.

I have an interesting report with transcription and findings, will scan and post. The timeframe from when things went wrong (02:10:05z until 02:14:28z) to impact is 4mins and 23s. Awfully short.

I don't know if it was allready posted here, this article was handed out in our company:

http://www.bea.aero/fr/enquetes/vol.af.447/point.enquete.af447.27mai2011.en.pdf

This one is more up-to-date:

http://www.bea.aero/fr/enquetes/vol.af.447/note29juillet2011.en.pdf

and the safety recommendations: http://www.bea.aero/fr/enquetes/vol.af.447/reco29juillet2011.en.pdf

According to the recommendations above, there is focus on crew traing and duty performance, which speaks for itself, although oddly I haven't seen any conclusions properly listed, which are the basis for any recommendation.
I fail to see the need for ELT emergency operation in an era where ADS is becoming standard.
Although AOA indication is useful, it can't replace proper situation awareness, where all necessary information is evident. Adding one other cue isn't helpful under the relevant circumstances.
Finally, these reports released to the parties involved and the public, are IMO less than helpful in preventing future occurences. What is needed is the clear identification of the prime causes of this accident. Don't tell me its frost on the pitot sensors, please.

I came across an interesting post where someone described a high altitude stall in the 777 sim...

http://www.pprune.org/rumours-news/466259-af447-final-crew-conversation-24.html#post6774438

Would we expect much different from a 744?

It affects any jet of this category. You know the power curve and the dilemma of slow speed flight: The slower you get, the more nose up is required to maintain altitude -- the more nose up, the higher the drag -- the higher the drag, the slower you get. At the final edge of the power curve there is not enough thrust to get out of this trap. Then the only way is to lower the nose. This is not easy either if you're very slow since your elevators need airflow to pitch the nose. This can be demonstrated in 747 sims.


Cheers,

|-|ardy

http://www.popularmechanics.com/print-this/what-really-happened-aboard-air-france-447-6611877?page=all

Terribly sad story.

Hi Hoppie!

Thanks for he link: I just completely read all the "story"... quite scary indeed. And the last sentence "Exactly 1.4 seconds later, the cockpit voice recorder stops. " really freezes me I admit...
Let's just hope that the causes that lead to loose those 228 lives will lead (or have already lead) to improving even further aviation safety.

Just horrible.

Why is there no indication on the instruments of the other pilots's stick position, so that each pilot can monitor the other pilot's manual work? A tiny little cursor would suffice without cluttering the display.


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Frumpy, that link you posted to the voice recorder seems to be down.

Any other way of accessing it?

shiv

The A330 flight control system incorporates two indication types for this:
a. A sidestick position indicator of the same seat position, first page. Used mainly for adjustment/. calibration.


b. A SD (System Display- center-low instrument panel) page which indicates control surface positions, and is automatiucally displayed for 20 seconds upon sidestick pressure application, second age. Used mainly to monitor control system response to pilot or autoflight control inputs.


As for lessons learnt from AF447 for prevention of future accidents, Pierre I am sorry but to me as accident investigator and manager of aviation units it seems that almost everything is being done to minimize cost damages to the operator, while pilot pay, pilot training and operator management intervention in pure flight issues which they understand little about (e.g. prohibition to fly manually), continue to be unhelpful and self defeating.

Thanks for the illustration. So, is the FLT CTL page automatically displayed only on the ground during the preflight procedures, to check hydraulics and max travel etc.? Is it similar to the 744's EICAS flight control indicators? As we all know, this EICAS stuff is to be blanked in flight by the crew to get a "clean" cockpit.

What I meant is a permanent indication on the flight instruments. Just a single small cursor, not all the control surfaces, just to show pilot action, perhaps something that auto-blanks when the stick is not moved.


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Took me a while - apparently the summed sidestick position is shown on the PFD when on the ground.



IIRC, there was an issue out of Jo'burg where the pilot was incorrectly using the sidestick position as a pitch reference on the PFD...

found it

http://aviation-safety.net/database/record.php?id=20040409-0

Can't answer for sure about flight auto-page display. Since the JFK A300 American Airlines loss of vertical tail due to captain overcontrol, Airbus added a rudder control travel limiter with airspeed, and want the pilot to also see rudder control position for that reason (mostly in direct law where protections are removed). It was always there but rudder control criticality to flight safety had been emphasized since.

Hardy, with proper piloting this all becomes secondary. The AF447 was in my opinion a piloting problem from the decision to not change course away from the tropical storm, to the pro-spin controls consistently held, to the water. Simply wrong actions which indicate aircraft system and fight control characteristics, pilot selection, up-bringing, company culture and currency training, all mediocre or worse, and surely negligent.
One has to be a design engineer to understand complex system malfunctions, and an experimental test pilot to master the three main control law with variants so that he can effectively and safely overcome their problems. Next these design engineers will convince the politicians of underworked workforces, that the way to go is to develop 850 passenger remotely controlled transports.

To add to the Jo'burg incident:
a. Training: Proper airline training and qualifications, should incorporate the following: Even with a type certificate for all variants, there should be some form of first flight instruction or supervision. I flew 1988 Frankfurt to Eilat on the brand new B757-200, the captain previously flew B767-200s. In the jumpseat next to mine was an airline check captain.
b. Pilot technique: During liftoff, the goal is to rotate to a pre-determind attitude at a predetermined rate of pitch to avoid tailstrike while attaining positive climbout. The pilot primary control reference is therefore pitch rate, attain a pitch attitude as a function of time. All other information, especially what control movement, is relevant as background information but secondary for piloting technique. Otherwise 14,500 of runway will be too short. Secondly, you are heavy, new model, high altitude runway. Accelerating too slowly in your opinion, no instructor there- go TO/GA early. After flight debrief the takeoff so the next one is better. Next, with so many CRM tasks during the roll, the PM is engulfed and therefore much less helpful in identifying problems early.

Shiv Mathur wrote

Frumpy, that link you posted to the voice recorder seems to be down.

Any other way of accessing it?

Seems to be down. I think it's similar to this one:
http://uk.reuters.com/article/2011/07/30/france-crash-crew-idUKLDE76S1IY20110730

Zinger wrote

The A330 flight control system incorporates two indication types for this:
a. A sidestick position indicator of the same seat position, first page. Used mainly for adjustment/. calibration

Correct me if I'm wrong, but isn't this indicator purely an armrest position indicator and has nothing to do with sidestick position indication?

Quote

Hardy, with proper piloting this all becomes secondary.

Assuming every pilot would pass the checks that you suggest, could we then assume that everyone of them will be perfectly skilled at all times and physically and mentally fit in every minute? Can you foresee every possibility, everything that could go wrong in the aircraft or in the pilot's mind?

In that sad situation, if I understand the text correctly, the left seat pilot and the Captain on the observer seat didn't know that the other pilot pulled on the stick all the time. That's why I wondered why there's no single indication to allow cross-checking. What if the PF is suddenly incapacitated during a critical flight phase without stall protection? If there was a conventional yoke, the PNF would see the PF's absurde action immediately.


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