Air Asia Crash Report : Cracked Solder Joint on Rudder Limit Circuit Board - Page 1
Forum section: electronics / general

author: rt
author_rank: Regular Contributor
timestamp: December 01, 2015, 12:22:14 pm
content: From:https://www.flightglobal.com/news/articles/circuit-board-solder-crack-cited-in-indonesia-airasi-419593/"Analysis of the aircraft's flight data recorder showed that around 30min after departing Surabaya on a scheduled service to Singapore, the aircraft's rudder trim limiter system failed, activating four master caution messages on the electronic centralised aircraft monitoring system (ECAM) within a 14min period."........"Maintenance records show that the aircraft had 23 rudder travel limited system problems over the previous 12 months. The problem was initiated by a crack in the soldering on the circuit board of the rudder travel limiter unit (RTLU).The investigation found that during the flight, the cracking resulted in a loss of electrical continuity to the RTLU, leading to its failure."Anyone have an insight into whether:1) they should have replaced the board earlier in the sequence of logged rudder travel system problems?2) any single board failures are not "detectable" faults at cockpit level?3) it takes a very serious incident to highlight these single points of failure?rt

author: EEVblog
author_rank: Unknown
timestamp: December 01, 2015, 01:53:03 pm
content: Report just released today:http://kemhubri.dephub.go.id/knkt/ntsc_home/ntsc.htmFrom page 68, a cracked solder joint in the Rudder Travel Limiter Unit (RTLU):

author: AF6LJ
author_rank: Unknown
timestamp: December 01, 2015, 01:56:41 pm
content: It would be interesting to see the subassembly and location of said subassembly that had that cracked solder joint.

author: coppice
author_rank: Super Contributor
timestamp: December 01, 2015, 01:59:58 pm
content: How come there was not sufficient redundancy to ride over this issue?

author: moya034
author_rank: Regular Contributor
timestamp: December 01, 2015, 02:05:38 pm
content: I wonder if that solder is lead free crap...

author: daqq
author_rank: Super Contributor
timestamp: December 01, 2015, 02:12:09 pm
content: QuoteThe whole board looks pretty old - at least 20 years old. I'd guess it was just old age.

author: nctnico
author_rank: Super Contributor
timestamp: December 01, 2015, 03:38:47 pm
content: Quote from: coppice on December 01, 2015, 01:59:58 pmFrom what I have read the pilots also screwed up badly. IMHO there seems to be too little attention in pilot training to tell false readings from good readings and act accordingly. It is not the first plane crash caused by pilots not knowing how to deal with an instrument failure

author: calexanian
author_rank: Super Contributor
timestamp: December 01, 2015, 03:45:32 pm
content: Let me put my QC work hat on now. This is a multi issue failure. First and foremost this is a cold joint. No two ways about it. The solder most likely never really flowed and bonded. The notch around the pin is a dead giveaway. How that kind of joint ever got past any sort of QC is shocking. Even at out company we catch things like that on our visual inspection and I can't imaging them making that board in quantities above what we do. If the part is that critical why is it not staked down with an eyelet and then soldered or some kind of pressure contact? This also smacks of board flexure. Why there would be no additional mechanical support is unknown, but I am sure it played a part. Unfortunate for what looks to be an otherwise stout design.

author: fivefish
author_rank: Frequent Contributor
timestamp: December 01, 2015, 04:24:28 pm
content: This is a bunch of Fails... but the insufficient pilot training seems to be the root cause.from nbc newsQuote

author: Maxlor
author_rank: Frequent Contributor
timestamp: December 01, 2015, 05:04:32 pm
content: Quote from: daqq on December 01, 2015, 02:12:09 pmThe plane was manufactured in 2008, so it was a fairly new plane.

author: ciccio
author_rank: Frequent Contributor
timestamp: December 01, 2015, 05:44:19 pm
content: Quote from: moya034 on December 01, 2015, 02:05:38 pmI'm pretty sure that all equipment installed into transportation vehicles (trains, cars, planes) is exempt from Lead Free crap.They knew that it was less reliable, and they wanted to avoid being called in courts..Best regards

author: SeanB
author_rank: Super Contributor
timestamp: December 01, 2015, 05:49:06 pm
content: Quote from: AF6LJ on December 01, 2015, 01:56:41 pmBeing rudder contyrol, most likely aft of the rear pressure bulkhead in the aft avionics bay or under the rudder itself in the space there. Might be an issue with vibration from the APU and normal operation. At least not as bad as the rudder controls of some aircraft, which had a known failure of wearing out the pin and sockets in the wiring loom plugs from vibration. They had a scheduled inspection and replacement cycle, as the pins wore to needle thin and snapped.

author: bitslice
author_rank: Frequent Contributor
timestamp: December 01, 2015, 05:57:57 pm
content: Quote from: calexanian on December 01, 2015, 03:45:32 pmIt's a funny sort of joint at all, someone tried really hard to screw that one up.The idea that that ever passed a QA check is just not believable, hopefully there is a long paperwork trail to lead back to the person who signed off on this.And why no conformal coating?

author: Wytnucls
author_rank: Super Contributor
timestamp: December 01, 2015, 05:59:59 pm
content: What is puzzling and hasn't been properly explained, is the cause for cracked solder joints onbothof the separate channels of the RTLU. One channel failure is benign and a complete failure is usually easy to handle, unless undocumented procedures are applied, like pulling FAC circuit breakers in flight. Even then, a competent flight crew should have been ready for the unexpected and react accordingly.PCB quality control may have been a contributing factor, although I didn't see any mention of that in the extensive accident report.

author: Zad
author_rank: Super Contributor
timestamp: December 01, 2015, 06:12:16 pm
content: I suspect the design goes back a lot further. The components look more like ones you would find in late 1970s electronics!

author: Wytnucls
author_rank: Super Contributor
timestamp: December 01, 2015, 06:20:35 pm
content: Late 70s is about right. The aircraft was launched in 1984. There may have been some PCB revisions since, but unlikely, due to the lengthy certification process.

author: macboy
author_rank: Super Contributor
timestamp: December 01, 2015, 06:58:45 pm
content: Quote from: Zad on December 01, 2015, 06:12:16 pmThe design is old, with DIP logic ICs and linear ICs in TO-99 cans, thru-hole resistors, etc. But stuff like that is indeed still manufactured. As Wytnucls said, they continue making the trusty old design because it is easier and cheaper than certifying a new one.

author: all_repair
author_rank: Frequent Contributor
timestamp: December 01, 2015, 07:12:53 pm
content: I took AirAsia flight twice from Singapore to Bali, and back. The way AirAsia used the plane worried me, and it gave me a feeling that their planes would run into all kinds of "fatigue" problems eventually. They were used like non-stop shuttle bus service with almost no interval break for the plane, 247, except mandatory maintenace break. Is it the same for all low cost air lines? How could the plane still be flying when they had the faults reported so many times previously, but root cause not found? The whole altitude of AirAsia on the safety is just appaling to me.

author: coppice
author_rank: Super Contributor
timestamp: December 01, 2015, 07:35:31 pm
content: Quote from: all_repair on December 01, 2015, 07:12:53 pmAll aircraft are operated with the minimum practical turnaround time for as many hours of the day as is practical. It doesn't matter whether its a budget airline or not. If an airline can't keep its utilisation rates up it rapidly becomes a bankrupt airline. Short range planes have a hard life, because take offs and landings are the main stress times. Its also hard to keep the utilisation up with some many loading and unloading operations. Long haul planes have a much easier time, and can be kept in the air for more than 60% of their life.

author: SL4P
author_rank: Super Contributor
timestamp: December 01, 2015, 09:05:34 pm
content: Quote from: calexanian on December 01, 2015, 03:45:32 pmPerhapsa little early on the dry joint theory...The pad looks to have lifted from the adjacent track, which suggests mechanical movement of some sort.Poor QC yes, but during initial manufacture or repair, which didn't ensure the part was snug against the board, thermal cycling, or the pin/hole sizing was incorrect - making the solder bear the component weight under vibration?Solder is not generally regarded as a structural part of an electrical joint.Just my 2c worth from looking at the photo.

author: rollatorwieltje
author_rank: Unknown
timestamp: December 01, 2015, 09:55:09 pm
content: Quote from: all_repair on December 01, 2015, 07:12:53 pmOn Flightradar you can see the history of most planes, you'll see that they are pretty much always in the air. This Ryanair for example:http://www.flightradar24.com/reg/ei-evdSome of these European flights are worse than Singapore - Bali, which is about 2.5 hours. Some of those flights by Ryanair are only about an hour, so these planes will have very high cycle counts.

author: Maxlor
author_rank: Frequent Contributor
timestamp: December 01, 2015, 10:56:39 pm
content: After having read the report, it's once again scary how much had to go wrong for the plane to crash. If only one of these things hadn't happened, the people on that machine would still be alive:- Even though the rudder travel limiter gave errors about two dozen times during the last 3 months before the crash, it apparently was never checked, instead the computer that controls it was repeatedly turned off and on again. This is surprising, since the error message displayed to the pilots specifically mentioned the rudder travel limiter. What was checked were electrical connections, but always while the plane was on the ground, and standing still.- The pilots decide to try a procedure forbidden by the flight manuals, rebooting a flight computer mid-air. They could have disabled it and switched to manual control instead.- Apparently, pilots these days rely so much on the autopilot, that it doesn't occur to them to fly a plane themselves, the old fashioned way, with a hand on the stick and an eye on the 4 most important instruments (airspeed, altimeter, vertical speed, artifical horizon). When the autopilot disconnected and the plane started banking because of the stuck rudder, it took 9 seconds for a pilot to take control. And then, he acted erratically, maybe being confused by the feeling of the plane rolling, as opposed to just watching the artificial horizon.- The captain gives ambigous commands ("level"... but what, pitch or wings?, and "pull down" - so is that pull on the stick (pointing the nose up) or pushing the nose down?) which the flying first officer interprets in the wrong way, stalling the plane.- The captain doesn't realize that the first officer is holding his stick way back, and that therefore his attempts to point the nose down were ineffective. If he had realized what the first office was doing, he could have disabled the first officer's stick with the push of a button.- Neither pilot seems to notice that near the end of the flight, the plane is basically dropping like a stone while being level. Again, a look at the most basic instruments would have confirmed that. Now, the report claims they weren't trained for this situation, but it doesn't seem far-fetched to me that had they realized what was happening, they would have come to the conclusion that they needed to drop the nose to gain speed.Now, I'm not saying that the pilots were incompetent. It's a difficult situation; night flight over the ocean, i.e. looking out the window tells you nothing. Several malfunctions, and all of a sudden the plane starts banking on its own. It seems likely enough that they were wondering whether they could trust their instruments (in fact, the captain having the active air speed indicator switched indicates that he doubted his readings). It seems like they lost situation awareness, the first officer who was flying (and stalling the plane) did for sure.It just seems crazy that all of those 6 points mentioned above had to go wrong for the plane to crash. If any one of them happened differently, chances are they would have made it. The thing that bothers me is that there isn't an easy single clear thing that we can fix forever so this never happens again. Well, there is maybe one thing... with critical infrastructure such as an airplane, it shouldn't be possible that the same error pops up two dozen times, and noone notices the repetitive nature. If every plane was assigned a caretaker that is aware of every minor issue concerning a given plane, such problem would be noticed, hopefully. I'm not 100% sure I understand the wording in the report correctly, but I think that was one of the recommendations they gave. Problem is, how to handle that in practice? They had technical systems for that, but they failed because those minor issues weren't logged. So that person would probably have to stay with the plane, and talk to the flight crews on a daily basis. Sounds like a shitty job, if that plane ends up on different places all the time.

author: cjuried
author_rank: Contributor
timestamp: December 01, 2015, 10:57:39 pm
content: Quote from: EEVblog on December 01, 2015, 01:53:03 pmThis is reminiscent of the NASA "Tin Wiskers" papers.Chris JuriedAudio Engineering Society (AES) Memberhttp://www.JuriedEngineering.comhttp://www.TubeEquipment.comhttp://www.Historyofrecording.com

author: MattSR
author_rank: Regular Contributor
timestamp: December 01, 2015, 11:16:42 pm
content: Damn - contradicting control inputs also put AF447 into a stall that caused the airplane to crash into the ocean.Boeings have the Captains and Co-pilots controls mechanically linked together, where as Airbus doesn't...

author: all_repair
author_rank: Frequent Contributor
timestamp: December 02, 2015, 01:54:23 am
content: Quote from: coppice on December 01, 2015, 07:35:31 pmI understand that utilisation rate is key to the business and survival, but AirAsia from my limited experience seems to be way-exceeding that. Both flights were late by a large margin, the schedule seemed not to allow for any slight delay either due to airport problem or weather problem. The crews were always in the rush on both occasions. When they talked, they talked hectically. If this is also a reflection of the cockpit, the pilots are unlikely to be able to do any thinking as they have to be doing catch up on top-speed allowable when they could. If any problem arises, more likely to do a reboot than a troubleshoot to understand and narrow down the problem and to do a proper report later, and also the over-utilization might be the reasons that nothing get reported as everyone is burned out after each shift.From that experience, I have banned AirAsia for my family traveling.

author: EEVblog
author_rank: Unknown
timestamp: December 02, 2015, 02:04:45 am
content: Quote from: SL4P on December 01, 2015, 09:05:34 pmA common misconception.By definition, a solder joint is used to mechanically fix the component (unless additional anchor measures are taken), whilst providing electrical connection too of course.

author: coppice
author_rank: Super Contributor
timestamp: December 02, 2015, 02:29:45 am
content: Quote from: EEVblog on December 02, 2015, 02:04:45 amIts not a misconception at all. All good reliable soldering techniques are based on reducing the loading on the solder to the minimum possible, making it merely a filler between other most robust materials. Single sided through hole boards put a lot of loading on the surface solder, and the solder cracks with monotonous regularity. Through hole plated boards move the loading burden to the holes themselves, where the solder is well supported by the plating and the component leg, and reliability is much better.

author: SL4P
author_rank: Super Contributor
timestamp: December 02, 2015, 10:41:30 am
content: Quote from: EEVblog on December 02, 2015, 02:04:45 amDave,I'm surprised at your response...!I was taught to solder by a euro-mil-spec type of guy many years ago, and not to say he knows everything, I spent 40 years working on the highest quality professional equipment - and all sources indicate that good mechanical design MUST be in place to support good soldering - for long term reliability, and immunity from mechanical failure over long periods of vibration and environmental cycling.Your experiences are respected, but on this one, I'd still opt for snug holes, correct (usually flush) component mounting and adhesive where needed - rather than none of the above!Cheers!

author: Psi
author_rank: Super Contributor
timestamp: December 02, 2015, 10:53:02 am
content: If the hole was "snug" enough to provide all the structural support then the molten solder wouldn't flow nicely all around the joint.Since solder flowing all around the joint is required the solder does provide structural support.

author: crispy_tofu
author_rank: Super Contributor
timestamp: December 02, 2015, 10:56:41 am
content: Quote from: all_repair on December 01, 2015, 07:12:53 pmNot only AirAsia, fatigue problems are quite common on short-haul planes.Control cables can snap (e.g.Air Moorea Flight 1121, this was also due to fatigue), parts of the plane can literally fly off (e.g.American Airlines Flight 587, the tail structure broke off), including part of the fuselage (Aloha Airlines Flight 243, which was an explosive decompression due to fatigue)...But a solder joint is probably unheard of...

author: EEVblog
author_rank: Unknown
timestamp: December 02, 2015, 11:14:11 am
content: Quote from: SL4P on December 02, 2015, 10:41:30 amIn that case all through hole boardsmusthave theeverycomponent physically secured to the board before soldering, and then stress taken off each lead by looping or whatever.In that case I must have been blind for 35+ years, including more than a decade of which was spend designing military PCB's with extensive experience in vibration testing and component modal measurement because I've never seen such a thing, never been taught to do such a thing, and never seen any standard for such a thing.Yes, mechanical securing of components is all part of good design practicewhen it's required, but the fact is that in the scheme of things almost every PCB ever made uses the solder joint as a mechanical support in some form for most of the components. To argue otherwise is to ignore reality of how boards are constructed.QuoteSure, and that's what potting and other methods are for when required.Mostcomponents do not get this treatment.Come on, seriously, in your 40 years of working on the "highest quality professional equipment" have youeverseen PCB that de-stressedeverysolder joint?QuoteUnless you glue or otherwise physically fix the body ofeverycomponent to the board and de-stresseverylead, by definition the solder jointistaking some mechanical stress. It must be, it's basic physics.You said it yourself, use adhesivewhere needed. Flush mounting and snug holes doesnotremove mechanical support from the components. In fact, you can't have a snug holeanda good solder joint with solder flowing through the holes to the pad on the other side. And if you are using a single sided board, then that's bad design practice for mechanically critical boards to begin with.

author: SL4P
author_rank: Super Contributor
timestamp: December 02, 2015, 08:21:17 pm
content: Obviously, we agree to disagree!"Come on, seriously, in your 40 years of working on the "highest quality professional equipment" have you ever seen PCB that de-stressed every solder joint?"- yes."Yes, mechanical securing is all part of good design practice when it's required..."That's all I was trying to say.In many cases, this is all that separates consumer /prosumer, and mil-spec assembly standards.

author: kaz911
author_rank: Super Contributor
timestamp: December 02, 2015, 09:16:30 pm
content: Mil spec is also country dependent.....Some countries specified curl mounts with 45 degree leg bend for high stress mill stuff when I trained.So resistors legs was given a 270 deg circle (3/4 gentle twist around a screw driver when prototyping) before going in to the PCB and on the other side a 45 deg bend from pad to the side of the fattest trace - to offset stress away from PCB and towards the 270 deg bend plus offsetting stress at the PCB at where the copper trace was strongest. And then resistor was floating about 1/3 of an inch above the boards for all the Mill spec ARC net and early 2 MBit (yes 2 Mbit) Fibre network adaptors we designed.That was around 1984 - and the Fibre 2Mbit was for " less option to snoop " - and a complete custom job for that particular country's military use). I had a roll of 2 km Fibre optics cable under my desk to " stress- test " with *G*.. and at that time it was worth a small house......

author: bitslice
author_rank: Frequent Contributor
timestamp: December 03, 2015, 08:01:00 pm
content: On that joint I can see corrosion of some sort, what caused that and why isn't the board protected from environmental effects?

author: AF6LJ
author_rank: Unknown
timestamp: December 03, 2015, 10:01:13 pm
content: Quote from: bitslice on December 03, 2015, 08:01:00 pmTo me it looks like dried rosin flux.

author: Cubdriver
author_rank: Unknown
timestamp: December 03, 2015, 10:15:27 pm
content: Quote from: bitslice on December 03, 2015, 08:01:00 pmWell, it did go swimming in the ocean for a while. It's likely weather resistant, but not intended for long term immersion since flying machines are typically creatures of the land and sky, but not the water.-Pat

author: SL4P
author_rank: Super Contributor
timestamp: December 04, 2015, 03:43:25 am
content: Quote from: cleaningOut on December 04, 2015, 01:12:10 amAn interesting idea... I guess simple wave soldering and simple reflow is no longer used in high-spec boards, and part of the vapour-phase production process is serious chemical cleaning before... and a weird mix of vapours in the soldering cycle - to ensure removal of contaminants and other unexpected surprises.I use ENIC gold passivated tracks - to help with better storage life - and soldering quality.ADDED: The sneaky gotcha is supplier or inventory that allows oxidation of leads while on the shelf. Airtight containers and component cleaning if available.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: December 04, 2015, 05:08:49 am
content: While solder does supply some mechanical support for components, it is tough to make it do the whole job for things in tough environments. Solder is an absolutely horrible structural material, with a different coefficient of expansion than most other materials used in PWBs, low fatigue life, low structural strength and worst of all poorly defined mechanical properties due to widely varying compositions in the as deposited case. This means that additional support may be required unless several conditions are met: Light components, small thermal stresses (small swings and limited number of cycles), low vibration (low amplitude and short durations) along with excellent initial quality and good joint design. Good joint design may forbid additional mechanical support if there is no mechanical relief between the additional support and the solder joint.Depending on the exact installation location of this board, it would have seen low to moderate levels of vibration for hundreds of hours, and moderate to extreme thermal cycling for hundreds or thousands of cycles. The thermal cycling would what would worry me for this joint. I have seen no front/back pictures of the joint, but the lead looks like it might be from a large component with pin leads. This configuration can force the solder to carry large thermal expansion loads.I worked on high reliability electronics my whole career, and failed solder joints were one of the most common problems. A lot, probably the majority related to the initial quality of the joints, but many were mechanical failures that occurred during thermal cycling or vibration. Gold embrittlement was often a problem - one of those things that is in the grey area between poor initial quality and the inadequacy of solder joints to deal with mechanical stresses.

author: bitslice
author_rank: Frequent Contributor
timestamp: December 13, 2015, 01:38:39 pm
content: Quote from: Cubdriver on December 03, 2015, 10:15:27 pmWhat I was getting at is that the electronics in planes must suffer from variable humidity, and every PCA I've seen that spends it's life outside of a computer case has some kind of conformal coating.Something that is expected to last decades would surely be given as much passive protection as possible?

author: SeanB
author_rank: Super Contributor
timestamp: December 13, 2015, 04:10:41 pm
content: Generally aircraft PCB will have a conformal coat on both sides, and larger components will also likely have extra support, either a tie down with some lacing twine, a clip riveted to the board, some epoxy applied after soldering and before conformal coating or a combination of these, followed by the conformal coat, generally a dip and brush coat or a mask for connectors then a spray application. Thus the coat can be thin and protective only, or so thick that the components will still work even if all the solder joints are broken.To add to that some conformal coats are reworkable, some are solder through and some need removal before rework, often being different for each board in a unit ( don't you love separate manufacturers) or different for each batch ( same again) so you need to identify and do the rework appropriately. Recoat after rework also needs a matching coat, so you might have 3 different solvent removers, 3 different rework tool sets and 3 different coating pack sets ( all with a very fixed shelf life and an even shorter use before xx after opening) to do this. some are not compatible with the other, either they peel off, do not adhere or worse reach chemically and destroy the board. Plus the solder through ones are nice and generate hydrogen cyanide gas on heating, so you need good fume extraction on soldering.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: December 13, 2015, 06:14:47 pm
content: Crash this Scarebus (Airbus) A320, AirAisa flight QZ8501 goes far beyond cracked-failed solder joints.Without knowing the specifics of this solder joint speculation and projection rules. Based on appearance only, it can be a cold solder joint, a solder joint that has been subjected to temperature cycling close to the solder's plasticity area and re-crystalized resulting in an intermittent joint, poor mechanical design of the pcb . Regardless, any aerospace-flight critical electronics and system must have redundancy to assure safety of flight.So what if the rudder limiter uP failed, the system should simply keep on functioning on redundant systems.As with most crashes of this nature it is not due to the failure of one single item, it is more often than not it is a chain of failures and actions that result in the disaster.Significant part of the problem lies in the inherent design of the ScareBus flight control systems and pilot ergonomics. ScareBus flight systems are designed from day one to keep the pilots from abusing the aircraft and take over if the flight system decided the pilots actions violate the programmed flight laws built into these systems.Commercial airlines were told and convinced by Airbus (ScareBus) that their passenger aircraft cannot get into stall situation due to the inherent design of their aircraft. This results in lesser pilot training that does not require extensive flight stall recovery maneuvers. This lowers pilot training cost and by projection pilot skills and competence .... a significant cost savings and operating cost reduction for the airlines operating Airbus (ScareBus) in their fleet.Most every aspect of Airbus (ScareBus) designs are about cost reduction sliding on the razor's edge of safety -vs- cost.Most reprehensible, irresponsible and a total Dereliction of engineering and management responsibly to humanity is the idea and belief that summing the two side stick controls without feedback is acceptable. Airbus ideology on this aspect of flight ergonomics is beyond defective and dangerous. It was for all the wrong reasons.If one reads the NTSB crash report, one pilot was pushing the side stick down, while the other pilot was pulling the side stick up resulting in a near zero flight control input to the A320 flight control system. This made stall recovery impossible and doomed this aircraft.What happened was near identical with the crash of Air France 447, same identical failure of the Airbus side stick flight controls total lack of feedback each pilot not knowing what they were doing.The QZ8501 flight crash report can be found here:http://kemhubri.dephub.go.id/knkt/ntsc_aviation/baru/Final%20Report%20PK-AXC.pdfIMO, if possible avoid flying on ANY Airbus (ScareBus) aircraft. The ScarBus name given to Airbus is from those who work in commercial aviation and fly these aircraft daily, that is their professional response to Airbus aircraft.As for a flight control comparison between Boeing -vs- Airbus:Bernice

author: MT
author_rank: Super Contributor
timestamp: December 13, 2015, 10:51:46 pm
content: QuoteLong time since i read the report and besides the strange design with the sticks i recall that there was even more to it as the software was responding in wrong way when it was already in a stall position, as the copilot mowed the stick forward to increase speed to get out of stall the software set off the stall alarm,he then mowed back the stick and could not understand the situation. This is the deadly combination of a untrained+arrogant/miss lead pilot and a faulty designed flight control system because he didn't followthe ancient rules of flying:Aviate, Navigate, Communicate. In short, fly the plane, everything else can wait.

author: Cubdriver
author_rank: Unknown
timestamp: December 14, 2015, 12:14:23 am
content: That does seem like a pretty awful design in that there's no coupling or tactile indication between the two side sticks (on opposite sides of the cockpit, and therefore not readily visible from the opposite seat) to let one pilot know what sort of input the other is applying to the flight controls. I don't understand how anyone could think this is a good control system.-Pat

author: Howardlong
author_rank: Super Contributor
timestamp: December 14, 2015, 12:37:14 am
content: Quote from: MT on December 13, 2015, 10:51:46 pmAlso in that order. So when the media ask why no Mayday was sent, you can be sure that either the pilot was dead or they were otherwise engaged, and as both a pilot and passenger that is the way it should be. Never underestimate the workload under such situations.

author: MT
author_rank: Super Contributor
timestamp: December 14, 2015, 06:22:38 am
content: Quote from: Howardlong on December 14, 2015, 12:37:14 am?! You mean that co pilot did the right thing when he was criticized in crash report for doing the wrong thing?

author: Cubdriver
author_rank: Unknown
timestamp: December 14, 2015, 06:25:36 am
content: Quote from: MT on December 14, 2015, 06:22:38 amWell.... His priorities were correct, it's his implementation of them that left something (ok, a great deal) to be desired.-Pat

author: Gixy
author_rank: Regular Contributor
timestamp: December 14, 2015, 06:43:01 am
content: Quote from: Cubdriver on December 14, 2015, 12:14:23 amThere is a light and an aural message saying "dual input". Moreover, a pushbutton on sidesticks allow the pilot to take priority. This has been used incorrectly by the pilot who didn'nt keep the button pressed.As others, Airbus planes are certified and statistics are there to demonstrate they are well designed.

author: MT
author_rank: Super Contributor
timestamp: December 14, 2015, 07:06:35 am
content: Quote from: Cubdriver on December 14, 2015, 06:25:36 amIf you implement something incorrectly you are probably not aviating if it leads to a crash. Bonin did severalerrors prior stall that caused them to get into a stall in first place. And when was in stall he was engaged in"other things" while maintaining the stall by pulling the stick backwards while he should had been engagedin the stall as such, apparently they didn't notice 54 seconds of constant stall warnings! Actually they didlot's of things they should not have done.

author: Cubdriver
author_rank: Unknown
timestamp: December 14, 2015, 07:39:23 am
content: Quote from: MT on December 14, 2015, 07:06:35 amHopefully not pull the nose up into an unsustainable climb attitude in the first place, but having done that a good first priority would have been, if nothing else, at leastreleasingthe back pressure on the elevator to perhaps let the plane return to its trimmed airspeed and possibly recover from the stall of its own accord. A more positive recovery could have been effected by lowering the nose and adding some power to completely alleviate the stalled condition.QuoteAhh yes, the L-1011 descending into the Florida swamp after the altitude hold got bumped off while all three members of the cockpit crew were engaged in troubleshooting a landing gear position indicator lamp. That was one of the first things I thought of when "aviate, navigate, communicate" was mentioned. No matter what's going on, it's important thatsomebodyflies the damned airplane!!-Pat

author: MT
author_rank: Super Contributor
timestamp: December 14, 2015, 07:47:33 am
content: Quote from: Cubdriver on December 14, 2015, 07:39:23 amPrecisely , when all systems have gone bananas and all instruments are gibberish and all flight lamps aredoing the 1970 disco to the bumped up beat voice of stall warning in the cabin, wings on fire, smoke incabin, osmabinladin in cargo bay what do you do as a pilot? Make sure the damned airplane is flying andland as quickly as possible!

author: Brumby
author_rank: Unknown
timestamp: December 14, 2015, 08:24:17 am
content: Quote from: Cubdriver on December 14, 2015, 07:39:23 amI couldn't agree more.Also, that they are properly trained to be able toflythe plane.I'm all in favour of automation to make the job easier - but IT MUST NOT be allowed to encourage an culture of complacency, dependence or laziness ... and it certainly is NO excuse for allowing pilots to be considered "qualified" at a lesser skill level.Reducing the skill level is asking for disaster - because its whenthings go wrongthat the pilot really needs flying skills. If he gets used to "pushing the blue button" to fix some flying problem and one day that blue button doesn't work he's going to have to start thinking about what to do. I don't know about you, but I'd rather he went through that exercise during his training.The other thing is flight system design that wants to 'negotiate' control inputs. This averaging idea sounds stupid and dangerous. I'd be happier to weld both control columns together through a couple of fixed linkages. The push-me-pull-you problem would soon be resolved.I see the same trend in motor vehicle technology. Stereoscopic imaging systems to automatically apply the brakes if you get too close to the vehicle in front and lane intrusion warnings. IMHO, this is not making driving safer, it is making it more dangerous. It encourages laziness and reliance on technology as well as furthering the culture, giving inattentive drivers something to blame if it doesn't work to their expectations.To promote the Airbus as requiring less skilled pilots is the most irresponsible policy out.JMHO(Rant over. Feel better)

author: Wytnucls
author_rank: Super Contributor
timestamp: December 14, 2015, 08:50:02 am
content: Quote from: Rupunzell on December 13, 2015, 06:14:47 pmIt does, with some minor hindrance, when both channels fail.Quote from: Rupunzell on December 13, 2015, 06:14:47 pmIncorrect. Stall recovery technique practice has been part of initial and recurrent training from day one.Quote from: Rupunzell on December 13, 2015, 06:14:47 pmOne pilot only should be flying the aircraft (Airbus or Boeing).The first thing one learns on the Airbus, is that there should never be any ambiguity about who is flying the airplane. It requires discipline. In this case, the first officer froze at the controls and the captain didn't know how to override his dangerous sidestick inputs properly.The only purpose of summing the inputs is to allow the conscious pilot to instinctively stop a manoeuver caused by an incapacitated colleague, slumping on his sidestick, until the priority take-over can be initiated.

author: Brumby
author_rank: Unknown
timestamp: December 14, 2015, 11:41:18 am
content: Quote from: Wytnucls on December 14, 2015, 08:50:02 am..or Cessna.QuoteA training issue, is it not?QuoteFair enough - but in the case of the push-me-pull-you situation, it would be good if there was a means to communicate that there were conflicting inputs, so it wasimmediatelyclear that there was a need for a priority take-over. It seems this was not immediately apparent and the pilots spent (however many seconds it was) wondering WTF? before realisation and the initiation of the take-over.

author: Brumby
author_rank: Unknown
timestamp: December 14, 2015, 11:45:24 am
content: On reading my previous post, it may seem I am attackingWytnucls- but please know that this is not my intention.I am more focussed on the the fact that the pilots were not doing the right thing and that the technology could be a contributing factor.

author: Monkeh
author_rank: Super Contributor
timestamp: December 14, 2015, 12:54:22 pm
content: Quote from: Cubdriver on December 14, 2015, 07:39:23 amNO!The engines on these aircraft are under the wings. In a stall condition you have next to no elevator or aileron authority. Pushing the throttles forward only serves to keep the nose up.

author: Richard Head
author_rank: Frequent Contributor
timestamp: December 14, 2015, 01:43:34 pm
content: Quote from: blueskull on December 14, 2015, 07:05:46 amProbably because they used pre-existing and certified electronics from around the 80's due to the exhorbitant cost of certification. TSO'd electronics is expensive to make and hence purchase.That's why certified small general aviation aircraft still operate on "steam"gauges.

author: Wytnucls
author_rank: Super Contributor
timestamp: December 14, 2015, 01:52:57 pm
content: Quote from: Monkeh on December 14, 2015, 12:54:22 pmExactly. Not only that. In a deep stall at high altitude, one may have to trim the aircraft manually nose down to regain some elevator control and forward speed.

author: Wytnucls
author_rank: Super Contributor
timestamp: December 14, 2015, 02:26:15 pm
content: Quote from: Brumby on December 14, 2015, 11:45:24 amThere should never be a 'push-me-pull-you situation' in any aircraft. The captain just shouts 'I have control' and the first officer has to sit on his hands. in the unlikely event that the pilot doesn't let go of the stick, as easily seen from the other side, priority take-over applies.In my experience, the full priority take-over procedure is seldom trained for, except at the initial Airbus conversion. That may change now, after this incident.The EgyptAir captain of the Boeing 767 flight 990 didn't have the luxury of a priority takeover button, which could have saved the aircraft:'The NTSB determined that the only way for the observed split elevator condition to occur was if the left seat pilot (the captain's position) was commanding nose up while the right seat pilot (the first officer's position) commanded nose down.'https://en.wikipedia.org/wiki/EgyptAir_Flight_990

author: Rupunzell
author_rank: Frequent Contributor
timestamp: December 14, 2015, 04:45:03 pm
content: Quote from: Wytnucls on December 14, 2015, 08:50:02 am

author: Howardlong
author_rank: Super Contributor
timestamp: December 14, 2015, 05:10:13 pm
content: This problem was fixed a very long time ago. It didn't stop inadvertent rudder inputs though.

author: Scrts
author_rank: Frequent Contributor
timestamp: December 14, 2015, 05:11:31 pm
content: Quote from: ciccio on December 01, 2015, 05:44:19 pmCars are strictly lead free. They can use lead in medical and military only afaik.

author: Wytnucls
author_rank: Super Contributor
timestamp: December 14, 2015, 05:17:14 pm
content: Bernice, it shows that you have no experience flying Airbus machines. You're just scaremongering, regurgitating past uninformed drivel. I'm not interested in a war of words about Airbus versus Boeing. I have flown many Boeing and Airbus airplanes. So have a lot of my friends. There is no great debate in the industry about which ones are better. I can assure you that both constructors are committed to make their products as safe as possible and no one should be afraid to fly on them.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: December 14, 2015, 05:49:48 pm
content: Not a matter of flying experience, this is basic human ergonomics. Nothing more, nothing less.Why no answers to the question put forth given your expertise experience in flying both Airbus-Boeing?BerniceQuote from: Wytnucls on December 14, 2015, 05:17:14 pm

author: Monkeh
author_rank: Super Contributor
timestamp: December 14, 2015, 05:54:08 pm
content: Quote from: Wytnucls on December 14, 2015, 05:17:14 pmI am rather curious about this statement from the FCTM, though: "The effectiveness of fly-by-wire architecture and the existence of control laws eliminate the need for upset recovery maneuvers to be trained on protected Airbus aircraft."

author: Howardlong
author_rank: Super Contributor
timestamp: December 14, 2015, 06:00:14 pm
content: Quote from: Rupunzell on December 14, 2015, 05:49:48 pmWith respect, I think Wytnucls has responded and answered more than adequately. What hasn't helped your cause is repetitive referral the Airbus as Scarebus which started off mildly amusing, then became irritating, and then then became a rant. Then you make accusations of French nationalism. I think we can draw our own conclusions on which side of the fence you're on, and are unlikely to want to be open minded enough on this to ever sit anywhere else. And by the way, I'm speaking as a yoke-only pilot!

author: Wytnucls
author_rank: Super Contributor
timestamp: December 14, 2015, 06:23:09 pm
content: Quote from: Monkeh on December 14, 2015, 05:54:08 pmIt is a strange statement. Airbus probably meant that an aircraft upset is very unlikely in normal law. Regardless, upset recovery is being practiced in the simulator.

author: Brumby
author_rank: Unknown
timestamp: December 15, 2015, 02:14:47 am
content: Quote from: Wytnucls on December 14, 2015, 02:26:15 pmWhile I have no quarrel with this - the fact is, it physicallycanhappen.My question is: WHEN conflicting inputs are being given HOW do the pilots find out?

author: Monkeh
author_rank: Super Contributor
timestamp: December 15, 2015, 02:46:56 am
content: Quote from: Brumby on December 15, 2015, 02:14:47 amThe aural warning 'dual input' should sound, and both sides of the cockpit have a visual indicator as well.

author: cimmo
author_rank: Frequent Contributor
timestamp: December 15, 2015, 03:40:47 am
content: I fail to understand why Airbus have not implemented haptic (force) feedback technology in their sidestick.The problem (as is frequently demonstrated) is that humans suffer from sense channel overload. Sure, there are red lights and green lights and aural warnings when sidestick priority is requested, but when the proverbial is hitting the other proverbial the cockpit is FULL of flashing lights and audio alarms.Expecting a human in a panic (who is trained to the minimum legally required standard) to differentiate one particular light or aural warning is naive.The solution is simple - make the sidestick move when inputs are made by the other pilot (but not by the autoflight system). As it stands there are no aerodynamic forces fed back to the sidestick - it just uses a centering spring.However, IF one pilot could FEEL (a completely different and unsaturated sense channel) when the other pilot has deflected the sidestick from neutral then this provides a prompt for that pilot to investigate WHY the other pilot is making a sidestick input.As a bonus, when the priority button is pushed AND THAT SIDE NOW HAS FULL CONTROL, then the feedback can be removed to let the pilot actually in control know that the other input is being ignored (by using that spare  sense channel).As an extra bonus - vibrate the sidestick that is overridden by the other side priority button to prompt that pilot to get his hand off the damn thing.This tactile feedback is essentially what happens in a Boeing - the mechanical linking of the control wheels achieves this. But since force feedback technology in joysticks is now consumer grade cheap, I am at a complete loss to understand why Airbus haven't implemented this at all, given that there now is enough evidence to show that the current system could work better.As some here have suggested, maybe it does come down to engineering arrogance?

author: Wytnucls
author_rank: Super Contributor
timestamp: December 15, 2015, 03:58:48 am
content: Quote from: Monkeh on December 15, 2015, 02:46:56 amYes, but the system is not installed on all machines. it is unclear if the AirAsia plane was equipped with the upgrade, but anyhow the captain was aware of dual inputs, as he pressed his priority button.

author: Monkeh
author_rank: Super Contributor
timestamp: December 15, 2015, 04:03:52 am
content: Quote from: Wytnucls on December 15, 2015, 03:58:48 amThe report seems to indicate that it was, however the alarm was suppressed by the stall warning. That is a flaw which needs rectifying.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: December 15, 2015, 04:07:43 am
content: Quote from: cimmo on December 15, 2015, 03:40:47 amThe Bombardier Q400 has a stick pusher which pushes the stick forward when it thinks it really really is a good idea. Unfortunately on Colgan Air 3407 the pilot just pulled back harder when it tried to push.The correct solution to a problem is to identify the root causes and eliminate them. Band-aids as permanent solutions are rarely a good idea.

author: cimmo
author_rank: Frequent Contributor
timestamp: December 15, 2015, 04:21:50 am
content: Quote from: Paul Moir on December 15, 2015, 04:07:43 amPresumably you think that the root cause of this problem is inadequate pilot training?I agree.But why NOT provide some form of additional system protection to mitigate against the inevitable human failure modes? There are hundreds of system backups and redundancies in aviation that are only there because the need for them has been demonstrated with a body count.Sometimes, 'band-aids' ARE the next best solution when the primary problem (humans) CANNOT and never will be fixed - unless we remove them from the cockpit entirely? (DroneBus?)

author: cimmo
author_rank: Frequent Contributor
timestamp: December 15, 2015, 04:24:45 am
content: Quote from: Monkeh on December 15, 2015, 04:03:52 amMy point exactly.Haptic feedback would be the perfect solution, but Airbus will never implement it as it would be an admission that their design philosophy is fundamentally flawed.

author: Brumby
author_rank: Unknown
timestamp: December 15, 2015, 04:29:00 am
content: Quote from: Wytnucls on December 15, 2015, 03:58:48 amAssuming that system was not installed and/or the alarm was suppressed, my next question would be "How long did it take the captain to work it out?" I'm sure the FDR would have that information - but if it was a number of seconds, then those were precious seconds indeed.

author: Wytnucls
author_rank: Super Contributor
timestamp: December 15, 2015, 04:31:49 am
content: Introducing new solutions is easy. The difficult part is to develop failsafe procedures for all kinds of failures, without overloading the flight crew and creating a new 'Gotcha' in the flight control system. The KISS principle comes to mind.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: December 15, 2015, 04:42:11 am
content: “Active sidesticks significantly improve the level of safety, making evident control inputs of pilots to one another and allowing prompt recovery actions,” says Roman Taskaev, chief test pilot for the MC-21 programme.Taskaev tested the failure modes of the active sidestick controllers in a series of recent trial runs in a ground-based simulator in Figeac, France, UTAS says.Cockpits equipped with decoupled sidestick controllers that do not provide active feedback have been highlighted in several aviation incidents. A left-seat pilot on Air France flight 447, which crashed in the South Atlantic in 2009, did not appear to understand that the right-seat pilot was pulling back on his sidestick and causing the aircraft to stall.https://www.flightglobal.com/news/articles/mc-21-ushers-active-sidesticks-into-commercial-aircr-411455/Bernice

author: Rupunzell
author_rank: Frequent Contributor
timestamp: December 15, 2015, 04:47:13 am
content: http://aviationweek.com/defense/positioning-captain-s-personal-camera-caused-near-crash-uk-a330Bernice

author: Brumby
author_rank: Unknown
timestamp: December 15, 2015, 04:51:04 am
content: I, too, am a supporter of the KISS principle which is why I like the idea of "I've got the stick, so I'm flying the aircraft."I understand it's not as simple as that these days - and there are good reasons why - but the connection between the pilot and the control surfaces just seems to be getting more and more distant.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: December 15, 2015, 04:51:25 am
content: 2.3.2 Active side stick"Contrary to passive side stick, the active side stick provides complete situational awareness by providing tactile forces calculated by the fly-by-wire computers during the flight (Hanke & Herbst 1999). Tactile feedback is obtained by electronic signals from aircraft system to the side stick through servo-motors.Since the active side stick is coupled with the aircraft dynamics it provides tactile and visual cues allowing for better handling and reduced pilot workload (Hegg 1994).The active side stick system is complex and requires more technical effort to assure its reliability (Hanke & Herbst 1999). For this reason, most commercial aircraft companies decide to implement a passive side stick as it is less expensive."https://publications.polymtl.ca/872/1/2012_MarieEveCote.pdfBernice

author: Brumby
author_rank: Unknown
timestamp: December 15, 2015, 04:54:12 am
content: Quote from: Rupunzell on December 15, 2015, 04:42:11 amI am puzzled why this did not seem to be self-evident with the designers.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: December 15, 2015, 04:54:18 am
content: I honestly don't know; airplanes are not my thing. However preventing humans from making mistakes is, and going by my experience with that, picking training as a root cause is usually a cop-out. Everyone forgets it, ignores it, or simply doesn't follow it sooner or later. Like you said, we're human so failure is inevitable if we rely upon ourselves only.The best solution in my experience is to design the process so the person isn't presented with the decision in the first place. The second best is to prevent him from making the wrong choice. That works really well: you make it a hassle to make (what you think) is the wrong action. Audible (primarily) and visual (very secondary) warnings are a distant third. Far too easily ignored when you're busy with something more important then them.To make a guess, the maintenance root looks like a real problem, as does design. Why did maintenance think having all those failures with those two units was OK? (I'm guessing this root really goes back to management with either budget or culture.) Why did they think some incantations with the circuit breakers was an effective repair? Why did the units, which Airbus thought so much of they put two in, both fall apart?

author: Rupunzell
author_rank: Frequent Contributor
timestamp: December 15, 2015, 05:06:30 am
content: Space Shuttle Discovery cockpit.Bernice

author: Rupunzell
author_rank: Frequent Contributor
timestamp: December 15, 2015, 05:45:00 am
content: Gulfstream G500, G600http://www.baesystems.com/en-us/feature/an-active-roleBernice

author: Wytnucls
author_rank: Super Contributor
timestamp: December 15, 2015, 05:51:06 am
content: Quote from: Monkeh on December 15, 2015, 04:03:52 amSince the PIC has to take over controls in a stall situation, an easy solution would be to require a constant push on the priority button until the stall warning stops and upset recovery has been achieved.

author: Monkeh
author_rank: Super Contributor
timestamp: December 15, 2015, 12:59:40 pm
content: Quote from: Wytnucls on December 15, 2015, 05:51:06 amWhich is what should have occured, but I am unsure how that resolves the issue of a critical alarm being suppressed by another alarm.

author: Esotech
author_rank: Newbie
timestamp: May 04, 2016, 02:55:10 pm
content: Hello all,If the picture shown is the actual device it would seem it has been exposed to water at some stage - the right hand side upside downed pcb shows what appear to be area's of both corrosion and rust as does the dry joint shown. It doesn't look like very modern electronics as everyone else has noted either and if it is the actual item I am very surprised that a component in a critical system could be allowed to get into this condition.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: May 04, 2016, 03:05:50 pm
content: Haptic controllers are more safe, but more expensive and less reliable. Maybe there is middle ground. One that would require almost no additional hardware, and a small amount of software. Just software that compares the controllers and activates a stick vibrator (on both sides) if there is significantly different input. Potentially an issue in terms of flight crew sensory saturation, but at least gives a signal that something may be wrong.

author: Monkeh
author_rank: Super Contributor
timestamp: May 04, 2016, 03:19:22 pm
content: Quote from: Esotech on May 04, 2016, 02:55:10 pmYou are aware that this thing CRASHED INTO THE SEA, right?

author: crispy_tofu
author_rank: Super Contributor
timestamp: May 04, 2016, 11:47:25 pm
content: Quote from: Rupunzell on December 15, 2015, 04:47:13 amI know this post is from last year, but it reminded me of this:https://www.washingtonpost.com/news/checkpoint/wp/2016/04/19/night-vision-goggle-case-cause-of-plane-crash-that-killed-14-air-force-says/