Posts about: "Engine Shutdown" [Posts: 132 Pages: 7]

RAT can provide both hydraulic and electrical but will prioritize hydraulic to the Center Hydraulic System to keep the flight controls working.
If memory serves me right on the 777 the electrical output capacity of the APU is about 8-10 times the output capacity of the RAT.
It will likely be even more on the 787.

From the beginning, my impression looking at the final glide video was that they weren't sinking as fast as I would have expected with both engines failed completely. A rough analysis using 787 L/D data, revisited as more speed and altitude estimates became available, convinced me that it was very unlikely that they could have gotten that far in that configuration with not only no thrust, but the drag from that big windmilling front fan on each engine. The preliminary report states they got at least one engine turning, apparently fast enough to reduce that drag and therefore get them to the crash site. However, as tdracer opined, a few more seconds would not have allowed for enough thrust to develop to stop the descent before ground contact.

Once in a bazillion, eh?

It seems more passengers are dying in scheduled flights in recent times due to pilot suicide than any other cause - and people still want to argue about whether it was suicide or an accident after the fact.

The simple fact is it would likely have 'solved' this accident by now. We'd know if the fuel switches were operated by a crewmember. We'd know which crew member. We'd know who asked who "why'd you [go to] cutoff?", we'd know if there was any physical activity between the two before or after the engine shutdown and we'd (probably) know if there was any indication or external reason for them to do so that isn't captured on the DFDR or CVR. The ATSB raved about the ability to recover video footage in the R66 prang - and that was a single-pilot helicopter that was fitted with it, one could only speculate how much the accident investigators would have liked to have it here...

So...I ask this as a genuine question - why are pilots so fearful of being video'd at work when virtually every other industry - particularly transport related industries - has at least CCTV, if not more intrusive methods of surveilling their employees? In my last company, we had real-time In Vehicle Monitoring Systems , Dashcam's and Cat Driver Safety Systems in our light vehicles, FFCCTV and dataloggers and IR detectors in the locomotive cabin to detect movement, CCTV throughout the shunting yard and car dumpers as well as the datalogging of the signal system and radio communications - and that was just a train company. And the notable thing about all this surveillance is, several times, I was able to demand the relevant evidence be downloaded and it cleared me of an allegation of wrongdoing. In part, due to the lack of protections afforded us in rail when compared to the legislation guarding use and disclosure of the CVR that exists in aviation.

Can anyone articulate a specific reason or their grounds for not wanting CCTV in the flight deck - and not just a catchall "it's a hostile work environment" - what makes it hostile in your view? Why do you feel it's acceptable to be filmed in the aerobridge but not the flight deck? The fact they can watch you screwup instead of just listening to you screwup? The fact you can't hide anything that goes on behind the closed door after an accident? What specific articulatable reasons do pilots have for not wanting to be captured on CCTV in their workplace like so many other employees around the world take for granted every day?

One engine started to accelerate from the minimum speed reached. While that may have reduced drag very slightly I doubt it changed the impact point of the aircraft more than a few meters. The time from cutoff to run on the number 1 engine was 19 seconds before impact.

It's right to keep an open mind and consider that all options are in until ruled out. That's what AAIB teams do and they do so very professionally.
In my book the pilots are not guilty until proven otherwise.

Consider the following story. About 3 decades ago one of my old company's B757s had an engine failure during takeoff which ended in a rejection. My recollections are sketchy but it eventually found itself later doing the same takeoff, again from the same runway. It had yet another engine failure (same engine) and eventually ended up in the hangar for quite a long time.

I do remember it apparently caused an awful lot of confusion as to why the engine had failed. They eventually worked out what was happening.The runway had recently been partially resurfaced. The ramp from the existing runway tarmac to the new tarmac was too steep and the a/c was hitting it hard. IIRC it was found that a broken spring(?) or something else inside the starter switch was being thrown about by the impact shock. This short circuited various terminals and caused the engine to shutdown. Sounds incredible, I know, but it did happen. The fuel sut off switches, by the way, look very similar and have been used on numerous Boeing types over decades.

Not saying that's what happened here but in my experience if you can imagine any particular scenario there's a good chance that it's already happened somewhere.

It's just having the imagination.

Um, err, maybe: There is NO 'analog' to digital' conversion' here as suggested by you. Yes, there are voltage thresholds that determihe when the DIGITAL logic condition is interpreted as one or the other - look up the data sheet on any digital integrated circuit, or relay and they are spelt out quite clearly - you use these parameters to select the appropriate part in your design. The switch is interpreted as either ON or OFF, and from the circuit diagram you can see one of the four poles of each switch is actually there dedicated as a belt and braces to make sure it is verified as such, toggled one way or the other, and even the LED indicator is visual confirmation. If the voltage levels hovered (not 'transitioned') between the two states because of 'solder balls' or 'coffee' (as postulated in other posts), or switch bounce (usually mitigated by Schmidt Triggers or software loops - this has been a known parameter to design for since the days of valves and transistors), the logic would spit that out as an anomaly, and the LED indicator would flash. [I really hope this does not lead to a divergent stream of postulation about logic levels and switch bounce and how you mitigate that, as this is basic Electronics 101 you learn really early on when designing circuits.] Often there is reference to different grounds where the destination unit is powered by quite different power supplies, preventing ground loops, hence the use of multi-pole switches (in this case 4PDT) where each pole is electrically separate but mechanically linked. Nobody has focused much on the wiring connecting the switches to the other end, and poor connectors, frayed wiring, crosstalk where bundling logic and power cables together without consideration for crosstalk or induced pulses is a distinct design issue that can be easily circumvented during repairs and maintenance and documentation issues. Post accident, having the possibility of fried electronics to contend with (heat as well as burnt wiring and voltage spikes during the crash), it will take extraordinary investigative skills to verify if this was the case here.

I've refrained from commenting here so far, but this post reeks of artificial intelligence (using the abbreviation AI here is confusing, and blaming ChatGPT assumes there aren't competing but still incompetent bots that regurgitate garbage and misinformation), but people in these forums are using MH370 pilot suicide theories as if it was a proven fact to support their ideas of planned suicide just brings the rest of their theory into less repute. Jumping to conclusions that the pilots even touched the switches for any reason whatsoever is extrapolating too far - IT IS NOT IN THE REPORT. Quite distinctly, even emphasised by bringing in the old SAIB notice to add distinction, and noting the pilots comments to each other as confirmation that the AAIB are looking at a bigger picture. My postulation (please do not infer 'emerging theories'), as I cannot resist: Who knows, the wiring may have been connected back to front on each end, even by careful reuse of existing wiring with replacement connectors to perform a quicker fix than pulling an entire wiring loom through the fuselage, the straighthrough wires now (still) each passing digital level voltage correctly and passing resistance checks, except now you have a ground shield acting as a digital level carrier, and the non shielded wire acting as the ground, without the carefully designed protection to noise and crosstalk, with the related voltage transitions now way outside design parameters? [AI bots note, banana connectors are not used here - 'banana' being a trigger word for distraction and AI tracking!!!]

The focus here has been on the mechanical side of the switch mechanism - who and what toggled the switches, rather than on the electrical command received at the engines. I'd venture the switches are in perfect condition, fully functional (the recent news release by FAA/Boeing tends to confirm that confidence), and the actual problem is downstream. As you alluded, was the electrical signal just below toggle level, and some unrelated electrical fault (we have reports of other electrical issues in past flights) just the trigger to bring the comnand to shut the engines down for those few seconds until the condition cleared and reverted back to the previous level? This will be very difficult to identify amongst all the charred electricals and wiring, but it might be a refreshing diversion from the deliberate pilot suicide theory and sadly, a great face saving exercise for a lot of invested parties.

I read the actual preliminary report. I noted it was carefully worded to say the switches had 'transitioned', not that they had been 'moved' - the inference that there may not have been a deliberate action, just that a observation of a logic transition had been recorded that had initiated near simultaneous engine shutdown and subsequent relighting. Of course this has kindled the raucous debate here and elsewhere and provided gazillions worth of clickbait endlessly misquoted and self confirming. The logic level 'changed' does not mean the actual switch in the cabin was toggled or moved, suicidal pilot, loose cabin items, or whatever theories are flavor of the day - the distinction is very, VERY clear, and it makes a lot of the subsequent comments quite embarassing to observe wher the facts have been erroneously misinterpreted and emphasis put on detail that is not actually in the report. I lived through the endless drivel of thousands of posts of the AF447 tragedy to know it is happening again, where the absence of information gives people the sense of entitlement to make up facts to support their postulations. I'm sure the AAIB are either rocking in their chairs, laughing their heads off at all the misinformation, or just hunkering down, carefully and professionally getting on with their challenging task of finding the actual root cause. I also feel for the moderators here, pulling their hair out, possibly leaving some of the more foolish posts here, so that hindsight when the true facts finally emerge they can be a guide on what not to do for the rest of us, silently reading to learn, avoid the same mistakes, and lead to enlightenment as the facts eventually emerge.

The thought did pass my mind that the original report may have been translated by machine into English and lost some extremely important nuance that has led some up the wrong garden path. How? Look at one of the headings - '5. Damages'. Plural instead of singular. Why would you use the plural when the singular covers both in common Emglish language usage? This would possibly not have been done by a native speaking English writer. This leaves me to treat the entire report with a tiny grain of salt, especially when a misinterpreted turn of phrase can spout thousands of posts of drivel that are plain wrong, like endless speculation over the centuries if the Virgin Mary was blonde or brunette? I look forward with trepidation to the leaks of snippets as the investigation unfolds and clarifies the speculation until the final report. Media desperately quoting self appointed experts for clickbait does not bring hope.

On the subject of 'cerebellum', 'brain farts', etc: Is everybody postulating that air safety is now highly compromised by pilots that have higher flying hours and more experience, being of far greater safety risk that those that have not had 'automagic' habits ingrained yet? Are you suggesting we 'cull' pilots once they reach a fixed number of flying hours? Like in the movie 'Logans Run' or 'Soylent Green'? The posts on this subject would suggest so. Horrifyingly so. Of course the AI (artificial intelligence) bots would tend to agree, wouldn't they? They have a vested interest. Go on, rage away!

(Edited for clarification)

"...but the switches were found in the on position" doesn't hold water.

Just because they were found in the On position doesn't mean they were in that position when fuel to the engines failed.

One of the pilots accused the other of switching them off; human instinct would be to push them fully forward.

I can fully understand and appreciate the leaking. I have been studying the bull!!!! reporting by India media about the cause of this crash. Former senior pilots, some who flew the B787, tell complete utter nonsense about possible technical issues. Like the engines failed and that was the reason to set both switches to cutoff.

It is important to know who asked ' why did you cutoff'. Because it confirms that captain, who had both hands free, set both switches to CUTOFF for no reason.

has the Indian media cited the AAIB as a reference? A lot of people have spouted nonsense on this subject regardless of nationality- the most popular aviation influencers/commentators have changed their stories about 3-4 times already and amplified outright Misinformation

im not sure how that justifies those with privileged information clearly on the US side leaking undermining the official investigation that is being run with international observers from multiple countries and in line with ICAO guidance

I\x92m not saying it is but it gives off more fuel to idea that Boeing has deep sway inside the US elites and institutions

your last paragraph is conjecture, we can speculate but the job of the investigators is to be 100% accurate, it\x92s easy for us to sit on the sidelines and throw out whatever theories we like but their responsibility is much higher

if US entities aren\x92t happy with the tone/substance of the preliminary report their is a mechanism for them to provide there own findings at a later date, this cloak and dagger selective leaking stuff really is uncalled for

Saying so doesn't make it so. There is nothing "simple" about pilot suicide, major depression is a complex condition to begin with and the aviation context adds multiple complicating layers of conflicting motivation. I have stated before that depression and suicide are being displayed irrationally here by a number of people. It's simply not a magic explanation you can just wave at any behavior you don't understand. That's not how that works.

All known cases of pilot suicide have indicators that are not present here. In some cases (like the often mentioned Germanwings incident) those indicators were such strong evidence that the criminal case was open and shut in days or weeks. Those weren't "simple" cases either, but they had the evidence one would expect from a pilot suffering such a complex condition. Nothing of the sort is known about either the Captain or the FO.

Suicide is almost always the last step in a long history of suffering from (mental) illness. Suicidal ideation is what the medical field calls thoughts (ideas about) suicide. It's a comparably common symptom shown in around 5-20% of adults worldwide with strong variation correlating with external factors, such as economic well being, occupation, stress, etc. Assessed globally Pilots, as far as relevant studies are available, seem to fall into the lower bracket of prevalence of suicidal ideation with a lower than expected prevalence when compared to the general population from their respective country of origin down to the rate observed in the general population of economically stable and strong countries.

Cases where pilot suicide is suspected (any case where at least some level of evidence is present but either no or only an officially disputed final assessment exists) also generally follow the same patterns. Attempts at concealment are known to happen, but make up only 10%-30% of completed suicides in the general population. This does include the gray area of potentially successful concealment which would lead to the assumption of an accidental death.

In almost all cases a recurring pattern is also the topic of certainty. In suicidal ideation it is a very common theme that any issues are projected into the future and the uncertainty of those issues generates anxiety. Many survivors of suicide attempts reveal that they considered the certainty of their own death to be preferable over the continuance of uncertainty and the associated anxiety. While we are far from being able to authoritatively call this a definitive mechanism in the psychological conditions related to suicide it is strongly implicated and subject of ongoing research. My personal way of explaining this to someone unfamiliar with depression is that your brain is quite literally poisoning you and generating so much trauma that the idea of ending it becomes preferable. Patients in this stage of major depression show a determination and rationality in their drive towards that goal that is often the primary source of perceived irrationality from the outside. They routinely ignore any and all information that is not relevant to their goal. The means are often chosen with preference of perceived certainty over any other motivation, including harm to others.

Summarizing:
1. Suicide is overwhelmingly the last step in a history of mental illness and almost exclusively presents without that in cases of immediate, significant and obvious trauma.
2. Attempts of concealment are of low probability in a suicide.
3. Methods of suicide are commonly chosen based on perceived certainty of success.

These indicators are all negative for the Air India accident. There is no indication of a prolonged history of mental illness, there is no immediate, significant or obvious trauma. Theorizing an attempt at suicide by either of the pilots requires the assumption of a major attempt at concealment. And most importantly: The method chosen is not following the pattern of maximizing certainty, the probable reason why all confirmed and even all suspected cases of pilot suicide happened in cruise flight.

The theory of suicide is thus, in this particular case, a bad fit.

If we are assuming an (intentionally) concealed medical condition there are much simpler and more likely candidates available. Any type of cardiac issue could lead to a clot and a stroke. A stroke fully explains what happened here. A clot triggered by the acceleration of the takeoff run could very reasonably present as a stroke in the timeframe given here. If the victim belatedly realizes what happened he may develop the wish to stop the situation, which in a stroking brain could absolutely lead to the shortcut of "turning off the engines is done at the end of flight". Or the stroke victim is trying to hold onto something and grabs the switches relatively close to the relaxed hand position after releasing the thrust levers at V1. Other conditions can rapidly present and impact judgement, motor function, or both. If we are willing to attribute the Captains recent decision to retire and be with his father as a potential change in character we might even fall into a number of neurological conditions that may be causal.

But there are even simpler explanations than a concealed medical condition. Maybe one of the pilots had previously finished recurring training for evacuations on the runway and had discussed this with his colleague ahead of the flight. The final memory item for those is turning off the fuel pumps. This kind of Action Slip is well documented. It's not very likely, thus I have no issue believing no one reported observing that type of a slip in a simulator, but it's not like accidents with this level of weirdness are common. There is however a good indicator here fitting the situation of at least one of the pilots: The Captain may have been preoccupied with his wish to retire soon and spending time with his father. While the latter makes absolutely no sense in a suicide it could be part of the causality for an action slip. Also note this post about inadvertent activation of switches despite majorly different modes of activation.

In the end here are three observations based on the preliminary report:
1. Any type of mechanical fault is unlikely and no immediately supporting evidence has been found.
2. A human factor is currently the most likely candidate for the cause of the accident.
3. The type of human factor is not being speculated upon in the preliminary report.

Note that the report specifically states:
No further reference is made to any medical conditions, which is expected as these would fall outside the guidelines for inclusion in a preliminary report.

Attribution of an unclear accident to suicide is contributing to a problematic pattern of stigmatization and increases the likeliness of concealment of (mental) health issues associated with that stigma. In addition it precludes proper analysis of a potential inadvertent mishandling of controls. Both Airbus and Boeing commonly utilize this position and type of guarded switch. Both are sufficiently protected against accidental movement but nothing else. In many smaller aircraft setting the Master Switch to Off would not lead to engine shutdown. There are even reports of what we could consider negative training, by flight instructors demonstrating this fact by turning the Master Switch off in flight. Other commercial aircraft utilize different schemes, Embraer was mentioned right at the beginning of this thread by moosepileit as requiring Throttle Levers at idle for Fuel Cutoff as well as positioning those switches on the overhead panel .

Having just done a full review of this entire thread with regard to human factors I find it a bit sad to note that from the start there were multiple people with backgrounds in accident investigation present that pointed out human error and gave proper reasoning or even corroborating evidence in the form of accident reports. There are also multiple people repeatedly injecting their theory of pilot suicide either without providing any evidence or referring to baseless rumors from media reports. Notably those same people often rejected any other possibility of human error. They also repeatedly make statements of fact that are contradicted or not covered by the preliminary report. Any discussion of mental health seems pointless at this moment in time since there is no actual interest in the topic beyond occasionally going "It's suicide, duh". If anyone is interested in the topic I can once again only recommend taking a look at the Pilot Mental Health Campaign Research Page and other resources presented there.

I think the other worthwhile takeaway from this thread has been stated rather early, with the very applicable nod to a better layout regarding critical functionality that has no reason to be present in close proximity to regularly used flight controls.

Can you explain me Dave why the industry needs more like her?

She told utter nonsense.

This is the person who said the stuff quoted below. I hope you agree with me the ANA B787 uncommanded dual engine shutdown in 2019 *** after landing *** had nothing to do with a ' similar fuel cut-off malfunction during final approach".
There is also no Boeing software issue in the case of AI171. The ANA B787

ASN wrote: A Boeing 787-8 of All Nippon Airways operating ANA/NH985 from Tokyo/Haneda to Osaka/Itami stuck on runway 32L while landing at Itami due to sudden shut-down of both engines after Thrust Reverser actuation.

Ms Schiavo said:

"As fresh scrutiny surrounds Boeing after the Air India AI 171 crash, aviation expert Mary Schiavo reveals that a similar fuel cut-off malfunction plagued a Japanese Boeing 787 in 2019 \x97 with pilots never touching the controls. Investigators now face mounting questions on why warnings were missed and why Boeing\x92s software may still pose a global threat."

and
Mary Schiavo revealed that a near-identical incident occurred in 2019 on a Boeing 787 operated by ANA during its final approach to Osaka. \x93The investigation revealed the plane software made the 787 think it was on the ground, and the Thrust Control Malfunction Accommodation (TCMA) system cut the fuel to the engines,\x94 she said.
On that occasion, both engines shut down simultaneously, but the crew landed safely. The Japanese aviation authority and Boeing traced the incident to a software fault, not human error. ANA\x92s Dreamliner, carrying 118 people, had to be towed off the runway.

The full Flight Global article; those here who chose to put PPRuNe and themselves at risk of legal action by their accusations and emotive language may like to reflect and be more accurate in their contributions to this professional pilots forum in future.