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Air Asia Indonesia Lost Contact from Surabaya to Singapore

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Air Asia Indonesia Lost Contact from Surabaya to Singapore

Old 1st Feb 2015, 10:37
  #2841 (permalink)  
 
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I believe a genu wine Airbus pilot and a close read of the manual would explain that absent pulling multiple breakers ( not resets ) full (NO protection) control is NOT available.
Precisely. And the Captain had to get up to pull the CBs because (a) they are behind the other guy's seat so it would take the other guy longer (b) with all the alarms going it would be hard to explain to the other guy what to pull. This was clearly not fun and games. This was urgently needing full control without computer veto, to get out of a stall caused by a false overspeed reading from a huge updraft.
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Old 1st Feb 2015, 10:40
  #2842 (permalink)  
 
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Get your heads out of all these details. It's smokes and mirrors.

The question is basically not if the skipper was out of his seat trying to pull any kind of HAL lifeline, it's not if the copilot could not fly a bus in degraded mode, it's not about where CB's are, or FAC/ELAC PRIM/SEC switches and how and when, by what OEB they might or might not save your day ....

The question is why do such questions about laws are still unclear after all these years and why do we have so many recipes as to how to deal with such upsets in a bus when ....

... such switchings and questions almost never arise with other FBW systems.

If you can answer that question, and even better remedy the unclear bus situation to the level of these other systems, then we are finally entering the correct path by eliminating at least one huge hole in a Swiss Cheese slice.
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Old 1st Feb 2015, 11:01
  #2843 (permalink)  
 
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following any approved FAC reset procedure.
AUTO FLT FAC 1 + 2 FAULT: When both your FACs are screwed!

After the A/P disengages, aircraft reconfigures to Alternate Law and you run this procedure:



Basically each FAC is sequentially reset (switched off and on again) and if that doesnt solve the problem, switch them both off for remainder of flight.
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Old 1st Feb 2015, 11:10
  #2844 (permalink)  
 
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I have two troubling issues. The first is an observation: I wonder who might be behind the leaked information that seems to point the finger at unusual pilot-actions and unresolved maintenance issues.


The second is: I would think during the early test flights of the FBW Airbus there was a big red button somewhere within easy reach that would disconnect the then-prototype computers/controllers and revert back to something akin to direct law.


The questions are, at what point did they get rid of the big red button, was it the right thing to do (probably) and mainly, should it now be reinstated?

Last edited by catch21; 1st Feb 2015 at 11:22.
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Old 1st Feb 2015, 11:44
  #2845 (permalink)  
 
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Originally Posted by catch21
I have two troubling issues. The first is an observation: I wonder who might be behind the leaked information that seems to point the finger at unusual pilot-actions and unresolved maintenance issues.


The second is: I would think during the early test flights of the FBW Airbus there was a big red button somewhere within easy reach that would disconnect the then-prototype computers/controllers and revert back to something akin to direct law.


The questions are, at what point did they get rid of the big red button, was it the right thing to do (probably) and mainly, should it now be reinstated?
The first side stick Airbus was an A300 with a side stick for the LHS pilot and normal controls for the RHS pilot.
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Old 1st Feb 2015, 11:46
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One of the 'leaks' suggested that the a/c turned left and 'wobbled' before the zoom climb.

Could this be connected to the fact that the rudder limiters were now no longer operational? And does pulling the CBs on the FACs mean that the AP drops out?

If any of the leaks are accurate, they suggest that a relatively inexperienced pilot was left flying a plane with no safety net, while heading into bad weather in the ITCZ.
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Old 1st Feb 2015, 11:46
  #2847 (permalink)  
 
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The flight augmentation computer ( FAC ) fulfills several functions independently of the engagement status of the FLT CTL/FAC pushbutton switches.
These functions are necessary for :
- the control of the speed scale on the primary flight displays ( PFDs ).
- the adaptation of gains of the flight management and guidance computer ( FMGC ) and elevator aileron computer ( ELAC ).
- the distribution of signals for the FMGC control laws
- the protection of the flight envelope in automatic flight ( speed limits for the FMGC, alpha-floor for the autothrust )
- the display of the rudderposition input.

Turning off both of the FACS leads to Alt Law and you have lost - VSW, VLS, S, F, Green Dot, Speed Trend, VMAX, VFE, VFE NEXT from your PFD. If you are not very speed aware it would be easy to inadvertently stall the aircraft. I would not be seeking to start climbing the aircraft at this point
The inop systems follwing a FAC1+2 failure are-
WNDSHEAR DET
F/CTL PROT
FAC 1 + 2
AP 1 + 2
A/THR
CAT 2
The PFD picture would be no Flight Director,(Red FD flag),and no limit speeds on the speed tape. The aircraft would be in alternate law with no autopilot or autothrust.The aircraft would be in trim so hands off it would continue on its previous trajectory.
The FCTM states-
Outside the normal flight envelope, the PF must take appropriate preventive actions to avoid losing control, and/or avoid high speed excursions. These actions are the same as those that would be applied in any case where non protected aircraft. The flight crew should consider descending to a lower altitude to increase the margin to buffet. Descending by approximately 4 000 ft below REC MAX ALT reduces significantly the occurrence of stall warning in turbulence.

Last edited by tubby linton; 1st Feb 2015 at 14:12.
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Old 1st Feb 2015, 12:31
  #2848 (permalink)  
 
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The question is why do such questions about laws are still unclear after all these years and why do we have so many recipes as to how to deal with such upsets in a bus when ....
Interesting question indeed ... and it seems that even the Airbus pilots did not arrive to find a coherent response .. to the point that some are even paying with their lives
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Old 1st Feb 2015, 12:33
  #2849 (permalink)  
 
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Foxxster,
You raise an important point about long standing technical issues. It is not practical for an ordinary pilot to refuse to fly a particular aircraft, especially if he is the sole refusnik. The FAC likely became an "ongoing issue" requiring "further pilot reports and investigation"
Finally there is acceptance of the FAC problem as a bit annoying, but sort of routine. Gradually, less reports are made and perhaps there will be one bulldog who will not let go. Multiple reports by the bulldog captain relieve others from the need to report. He is doing such a good job and why should others risk their positions with repetitive reports? Perhaps he will get a hard time in the sim, have his long awaited leave cancelled or get a crappy roster with no overtime or allowances.
People don't want to have bad news pushed at them day after day. My experience like the scenario suggested, but with determination, saved an aircraft just in time. There was other case where determination was insufficient and an aircraft from another airline, with pax, was lost with just one or two survivors.
Being a bulldog can have its disappointments. How easy it is to just go with the flow!
I hope that this philosophy can be recognised and accepted. It is not taught by operators who are more interested in keeping their aircraft flying. It is not pushed in crew management courses and is very rarely, if ever, discussed. If 5000 pilots read this post, perhaps one or two will become a little more assertive until their job is at risk.
The clue is not to be found in flight control laws, but in determination to complete every flight safely.
There are so many considerations. A major one is to insist on sufficient fuel to give wiggle room for lower levels, TS avoidance, unexpected weather etc. Minimum flight plan reserves are often insufficient when all reasonably identifiable factors should be allowed for.
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Old 1st Feb 2015, 13:01
  #2850 (permalink)  
 
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Auto flight,

I agree with a lot of your comments, however.....

What airline do you work for ?

If you work for an airline where penalties are the norm for a pilot that takes an unacceptable aeroplane ( bulldog attitude is not required.....EVER, it's my life and the passengers after all), then you need to change airlines, or, at the very least, report it.

I have had a number of occasions where maintenance have suggested I take an aeroplane which, in consultation with my offsider, was unacceptable, no bulldog, just not acceptable. Never a word from the "bosses".

Pressured into taking an unacceptable aeroplane is, and never will be, an excuse.

Cheers
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Old 1st Feb 2015, 13:25
  #2851 (permalink)  
 
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Katslf

to get out of a stall caused by a false overspeed reading from a huge updraft
Airspeed fluctuations caused by windshear are REAL, not false, and have to be dealt with in the normal manner. The aircraft flies by air, not by ground.

However, because this aircraft was lower than they wanted to be, it is reasonably certain that the windshear would not cause an overspeed. If you are 4,000ft below optimum, the buffet margins should be wide enough to cope with everything bar disappearing into the center of a CB, and we can be fairly sure they were not doing that.
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Old 1st Feb 2015, 13:35
  #2852 (permalink)  
 
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I'm amazed that some poster mix FAC & PRIM (FCPC)!!!
FAC its for A320 whereas PRIM its for LR (330&340)

Last edited by greenspinner; 1st Feb 2015 at 13:49.
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Old 1st Feb 2015, 13:59
  #2853 (permalink)  
 
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Bentrees

If you work for an airline where penalties are the norm for a pilot that takes an unacceptable aeroplane, then you need to change airlines, or, at the very least, report it.

Pressured into taking an unacceptable aeroplane is, and never will be, an excuse.
Sorry, Bentrees, but Bulldog is right. It happens.

Once you get into the lower-order airlines, pressure to take ongoing defects and multiple defects is an everyday event. And yes, if you make waves, another pilot will be found to take the aircraft and your next sim-ride will be a real problem. And your mortgage will be on the line once again.

And let's not have this silly business of, 'oh, leave the airline and go elsewhere'. Where to? Piloting is not like working as a shop assistant, where you have hundreds of alternatives. You will probably end up flying in a third world country, where the engineering will be worse anyway - so you may as well just take the defect. And some of these intermittent defects go on for months,** because, as Bulldog said, it becomes the norm. Crew chatter will just say, 'oh, watch the thrunge-actuator controller on Charlie Alpha, it is always failing.' 'have a good flight now.'....

This is not a pilot problem, nor is it an engineering issue, the real problem is a regulation issue. The authorities are more than keen to reprimand pilots, because that is simple; but when it comes to bellicose operators, they become supine to the point of being horizontal. It is not beyond the capabilities of regulators to demand if a system that has been snagged more than six times, then that aircraft is grounded until the whole system is overhauled (rather than just box-swapping). And also stipulate that a non-revenue flight-test is done before flying the line again (how many times does that happen, eh?)

But the authorities will not do it, because it is much easier for them to throw the ball back into the crew's court. Let the crew take the pressure and blame, and lose their jobs - much easier than putting your own neck on the line by arguing with the fat-cat lawyers from Bellicose Airlines Ltd.


** (This was the cause of the Turkish Airlines accident at AMS - long before any mis-handling by the crew became an issue.)
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Old 1st Feb 2015, 14:21
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- the adaptation of gains of the flight management and guidance computer ( FMGC ) and elevator aileron computer ( ELAC ).
Would this be a plausible scenario in an Airbus? The FAC for whatever reason (malfunction, stuck AOA sensor, etc.) was commanding ELAC to command the elevator to nose down and the PF pulled the stick back to try and override this. When this didn't work, the PNF pulled the CBs on the FAC which returned the elevator to manual control (e.g., responding to stick inputs with no limits or protections), but since the stick was already pulled back, a sudden zoom climb ensued before the PF realized the consequences of pulling the FAC CBs.
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Old 1st Feb 2015, 14:30
  #2855 (permalink)  
 
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Boxes vs cabling etc

If the switching of FAC units with an other aircraft did not remove intermittent malfunctions, I should rather suspect connectors, cabling or sensor errors than FAC-unit problems.

Is the reason not to make the preliminary report available to the public now a try to conceal something that would look too bad? Today, such reports tend to leak anyway when times goes by, so what is gained by a delay?
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Old 1st Feb 2015, 14:45
  #2856 (permalink)  
 
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Not a pilot here...

I have read that in case of both FAC failure there is no overspeed protection and max speed is set to 320 KT, does it means that HAL will act if the speed is above that?could that explain the climb?
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Old 1st Feb 2015, 14:59
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After any accident involving an Airbus, there are always lengthy threads populated by old timers writing with the Star Spangled Banner proudly playing in the background that everything was safer in their day (despite all the evidence to the contrary), that the cause of all Airbus crashes is 'HAL', and that none of this would have happened if the computers were just turned off and pilots allowed to fly the plane.

Maybe there are impressionable types who don't appreciate this for what it is (Luddism mixed with a healthy dose of jingoism), and maybe there is a responsibility for some PPRuNe posters to cut some of the crap... Worth thinking about.
Brave words. The pax on this ill-fated flight can take comfort that they were martyrs for the anti-Luddite movement.
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Old 1st Feb 2015, 15:15
  #2858 (permalink)  
 
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Other way round

FrequentSLF

NO - if there is NO OVERSPEED PROTECTION it means that famous HAL will NOT interfere when speed becomes too high.

The speed limit is then lowered to 320 kts, meaning, pilots, don't fly at a speed above 320 kts. The reason for this lowering of the limit speed is so that you will have a larger margin to the real limit of Vmo, to give some leeway in case you do a sloppy job of monitoring your max speed limit. With HAL operational, IT will do that monitoring job for you.
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Old 1st Feb 2015, 15:34
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Being old school, reading the 140 plus pages to this incident is almost a repeat of the comments posted on the AF accident. It appears that flying the Bus, understanding what is shown in the glass in front of the crew is almost akin to two dogs watching TV.
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Old 1st Feb 2015, 15:47
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Question training wheels 31 Jan posted

re a blog
According to this blog, a news reporter who has leaked information about the technical status of the aircraft, FAC 2 of the accident aircraft (PK-AXC) was swapped with one from PK-AXV two days before the accident.
But if the problems resulted IN or were due TO a flaky sensor or wiring fault then . . . ??
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