Article: What really happened on Air France 447

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killbilly

killbilly

Vocals, Lyrics, Triangle, Washboard, Kittens
Pretty good read! I did notice in the comments someone had mentioned that the AP had trimmed full nose up at some point. If this is true, wouldn't there be a stab trim warning of some sort as that happened? In any event, it makes it sound like having 2 FO's in the flight deck is something that equals instant death or something. Certainly a good lesson in CRM here.
 
I am sure that it was trimming as a result of the control input. Not exactly an autopilot thing, more of an FCC response.
 
seagull said:
I am sure that it was trimming as a result of the control input. Not exactly an autopilot thing, more of an FCC response.
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Right! Didn't even consider that...given the non stop nose up control input that makes perfect sense.
 
It's astonishing/sad/confusing that such a state of the art aircraft with an experienced crew could essentially "fly" the plane into the ocean. That such a system would spend so much time "training" pilots that they can't fly outside a prescribed envelope, then when the stuff hits the fan that goes away and the pilots aren't practiced on that is sad. I suppose the good is that this will never happen again for that reason.
 
I'd love to see a line by line analysis of this accident by a guy current on the 330. IIRC, the last thread on it was very interesting, but sort of fell apart because none of was quite sure how the thing works (myself especially).
 
killbilly said:
http://www.popularmechanics.com/technology/aviation/crashes/what-really-happened-aboard-air-france-447-6611877

It's kind of a harrowing article, but I walked away with a question:

Why do the synchronous sticks on the Airbus average the inputs if one pilot is pulling back and one is pushing forward?

I assume that people much smarter than I am had very good reasons for designing this way, but I can't think of a reason why.

I'd appreciate some input from someone who knows.
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I know this doesn't really answer your question but just some food for thought. The system described below is from the A320 but they are virtually identical.

There is a "Dual Input" aural warning to alert you that it is happening. You can also override the other pilot's inputs by pressing and holding the priority push button (basically the red button the stick that also serves as the autopilot disconnect). The pilot pushing the button will override all other commands until the button is released or after 40 seconds the other pilot is locked out. Think of it as if the other pilot is incapacitated and slumped over the stick.
 
boondr said:
It's astonishing/sad/confusing that such a state of the art aircraft with an experienced crew could essentially "fly" the plane into the ocean. That such a system would spend so much time "training" pilots that they can't fly outside a prescribed envelope, then when the stuff hits the fan that goes away and the pilots aren't practiced on that is sad. I suppose the good is that this will never happen again for that reason.
Click to expand...

Still a fascinating analysis that really leaves us asking questions about automation, CRM, training, high altitude flight envelope training etc.....

It's most likely that they've never experienced a scenario such as this in a simulation. I've yet to see something even remotely similar during a training event. Then consider the significant differences in Airbus flight "laws," and perhaps the crew's and especially the junior FO's (who was the flying pilot) training and experience with fly-by-wire. What if (a big what if) most of his flight time aside from minimal GA training was in fly-by-wire aircraft that were basically unstallable. Maybe then it makes sense to hold full-aft side stick. Combine that they go from a "STALL" aural warning to no aural warning, that suggests an improved condition.... Granted a 10,000fpm descent would suggest otherwise.

Would this accident have happened if the captain had been in the left seat. Perhaps years of flying traditionally controlled aircraft would have tripped a more conventional response. Also then as the author suggests there would have most likely been less question of who was in control of the aircraft. In the actual scenario there was no clear change in flying responsibilities throughout the event. Had the CA been in the left seat with the JR FO, I would suggest there would be less ambiguity of who was in control of the aircraft.
 
dvtpilot said:
Pretty good read! I did notice in the comments someone had mentioned that the AP had trimmed full nose up at some point. If this is true, wouldn't there be a stab trim warning of some sort as that happened? In any event, it makes it sound like having 2 FO's in the flight deck is something that equals instant death or something. Certainly a good lesson in CRM here.
Click to expand...

Software engineer point of view here. I studied the 320/330/340 flight control logic in undergrad for both software engineering and human-computer interaction. Airbus current pilots please speak up if I am blowing this.

The THS in normal law will always strive to neutralize the elevators, based on the load factor order. The flight control computers, not the autopilot, trimmed the THS to full nose up and left it there. The warning you get in alternate law is an amber "USE MAN PITCH TRIM" annunciation on the PFD below the FMA, as there is no automatic trimming (if I recall correctly, although it's been a while since I read up on this) in alternate law.

Elevator small. THS big. Obvious consequence.

On the FBW 'bus, when everything is working, you don't touch the trim wheel save to set takeoff stab trim. Pull to an attitude and let go and there it stays.
 
Both today, and immediately after the accident, as speculation came to the iced-over pitots, I thought "why not just go to a known combination of pitch and power to give approximate level flight?" The fact that they were already at cruise would make this even easier. You lose airspeed, fine, if you hold cruise power and roughly level pitch/bank, you'll be flying straight and level. Maybe not to RVSM standards, but at least you would still have control of the aircraft.

I've never flown an Airbus, so obviously I'm hardly one to speak of experience, but why would you ever be IMC and not at least have the pitot anti-ice turned on?

Now, reading this, I am still learning things about the way Airbus does stuff that I just can't say make me feel warm and fuzzy. Most importantly, I had NO IDEA that you couldn't tell what the other pilot was doing, as the sticks don't' move together. Who the hell decided that was a good idea?
 
Baronman said:
Would this accident have happened if the captain had been in the left seat. Perhaps years of flying traditionally controlled aircraft would have tripped a more conventional response.
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A major US airline experienced a similar problem in their 330 couple of years before the AF accident and recovered without any major upset.
 
I just have my PSEL/IR so not much to go on here - but I cant think of a single situation where it would be good to have a control system that averages the difference of two pilots fighting each other without providing an indication of what is going on physically or audibly (the article doesnt mention an aural alarm regarding this). Maybe someone can help me out.
 
A Different Take (speaking from experience) - I participate in forensic investigations, and what happens behind the scenes is rarely the story given to the press. . Like the TWA 800 ocean crash off New York, we can't be sure what happened to Air France 447. . First a dispute erupted between Brazil's first-on-the-scene search results, and France who disputed Brazil's claims. . Then a six-way fist fight between Airbus, Air France, the French Government, Boeing, international intelligence and law enforcement agencies. . Like the BP oil platform explosion and spill in the Gulf of Mexico, there is an initial race to shift blame (legal and ethical). . Then the parties realize that the publicity is threatening business and political interests, so a quiet closed door negotiated settlement is reached. . This type of accident is different than a Cessna 150 overshooting the runway at a small airport. . The NTSB & FAA get a free hand to investigate those without political interference. . However, in major disasters like this, with big money and international politcal interests involved, the incident "cause" is negotiated. .

In recent years, major aircraft accident investigations have becoming highly politicized, like everything else. . Investigators and researchers are no longer given a free hand to call them like they see them. . In accidents of this magnitude, visiting buraucrats and investigators from outside the avaition field are often being given the senior positions in these investigations. . They answer to the politicians who appointed them, not to transportation officials (again - TWA Flight 800 is a good example). . There is much more to this story.

Tensions Dog Air France Crash Investigation -" The tensions were laid bare inadvertently by a senior official following days of finger-pointing in the media and the disclosure that the A330 aircraft suffered no major faults......The reputations of both companies are on the line over one of the world’s most shocking and unexplained disasters and both face a criminal probe as well as potential claims from families. The black box investigation is not only happening under the glare of media attention but also comes weeks before the Paris air show, at which Airbus hopes to announce large plane orders."
http://www.aviationbrief.com/?p=1667

Legal probe over AF447 crash has ‘no grounds’: Air France - “Air France opposes this indictment. We believe it holds no grounds,” says a spokesman for the carrier. “At this stage, the examination has served no default and there is no direct relationship between the facts indicated by experts and the accident.”

http://www.flightglobal.com/news/ar...af447-crash-has-no-grounds-air-france-354593/
 
pressclick said:
I just have my PSEL/IR so not much to go on here - but I cant think of a single situation where it would be good to have a control system that averages the difference of two pilots fighting each other without providing an indication of what is going on physically or audibly (the article doesnt mention an aural alarm regarding this). Maybe someone can help me out.
Click to expand...

You would get a "Dual Input" aural warning.
 
Autothrust Blue said:
Software engineer point of view here. I studied the 320/330/340 flight control logic in undergrad for both software engineering and human-computer interaction. Airbus current pilots please speak up if I am blowing this.

The THS in normal law will always strive to neutralize the elevators, based on the load factor order. The flight control computers, not the autopilot, trimmed the THS to full nose up and left it there. The warning you get in alternate law is an amber "USE MAN PITCH TRIM" annunciation on the PFD below the FMA, as there is no automatic trimming (if I recall correctly, although it's been a while since I read up on this) in alternate law.

Elevator small. THS big. Obvious consequence.

On the FBW 'bus, when everything is working, you don't touch the trim wheel save to set takeoff stab trim. Pull to an attitude and let go and there it stays.
Click to expand...

All true except one minor thing regarding alternate law indicators...the "USE MAN PITCH TRIM" on the PFD is not necessarily an indicator that you are in alternate law. You could be in the next step down which is direct law. The best indicator is to look at the ECAM which will tell you which law you are in other than normal. "F/CTL ALTN LAW". Splitting hairs I know but not knowing the proper way to interpret which law you are in can have severe consequences since you won't know what protections are lost.
 
However you look at it, this don't bode well for the Puppymills. "Captain, what's all that crazy lightnin' stuff outside"? From the F/O on an A330 flying between Continents? This must be a joke.
 
Cav said:
All true except one minor thing regarding alternate law indicators...the "USE MAN PITCH TRIM" on the PFD is not necessarily an indicator that you are in alternate law. You could be in the next step down which is direct law. The best indicator is to look at the ECAM which will tell you which law you are in other than normal. "F/CTL ALTN LAW". Splitting hairs I know but not knowing the proper way to interpret which law you are in can have severe consequences since you won't know what protections are lost.
Click to expand...

Fair enough.

Question: how far down is F/CTL ALTN LAW (PROT LOST) in the message stack?
 
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