There have been several similar incidents with Asian carriers. There is a cultural consideration there.
Air India Flight AI171 (Boeing 787-8) Crash
- Thread starter john_pifer
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There are legitimate concerns about digital electronics (especially running software) and random failures when things are controlled by computers or electronic paths involving digital circuitry. Obviously the millions of lines of software code and however many digital electronics can fail randomly just like any other part. And there's certainly a possibility of actual hardware failure. I'm pretty sure that's the biggest worry about EMP with regards to aircraft. The operating state of the electronics can get scrambled even if it doesn't end up permanently damaging them.
I've studied it before. Soft errors (especially in aircraft subject to higher amounts of cosmic rays) can mean "bit flip". Static can also cause soft errors. Or oddball situations such as latch-up (which actually causes transistors to burn up). Even something as simple as a single event upset causing cascading errors. If the reset line on a particular piece of electronics gets flipped to active, that could be pretty bad if it restarts.
https://en.wikipedia.org/wiki/Single-event_upset
I've had a few cases where I plugged in something into my computer and it just went crazy. I could tell it was "on" because there was a buzzing coming from it. Couldn't do anything to power it down other than opening it up and then pulling the battery connector. Now I would hope that aircraft electronics have better redundancy and/or means to reset compared to a consumer-grade laptop, but it's still a possibility.
Apparently there have been a few aircraft failures where they couldn't find anything and concluded that the most likely scenario was a random soft error. I think this one is the best known example where it was suspected.
https://www.atsb.gov.au/sites/default/files/media/51227/AO2008070_prelim.pdf
Found him. Watched his video.
He is firmly in the “pilot suicide” camp, and bases it partly on his interpretation of Indian culture and partly on the conversation.
I think that’s premature, and mildly distasteful, as explained above.
edyvw
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There is good amount of leadership literature that uses accidents by Asian airlines as case studies.
MolaKule
Staff member
@y_p_w Undoubtedly you have never done Fault Tree Analysis. This is done for both software and hardware in a drill-down fashion, from the system level all the way down to the PCB and component level.
"Fault tree analysis (FTA) is a type of failure analysis in which an undesired state of a system is examined. This analysis method is mainly used in safety engineering and reliability engineering to understand how systems can fail, to identify the best ways to reduce risk and to determine (or get a feeling for) event rates of a safety accident or a particular system level (functional) failure. FTA is used in the aerospace,..FTA is also used in software engineering for debugging purposes and is closely related to cause-elimination technique used to detect bugs.
In aerospace, the more general term "system failure condition" is used for the "undesired state" / top event of the fault tree. These conditions are classified by the severity of their effects. The most severe conditions require the most extensive fault tree analysis. These system failure conditions and their classification are often previously determined in the functional hazard analysis." WIKI
Single Event Upset (SEU): Radiation-induced errors in microelectronic circuits caused when charged particles (usually from the radiation belts or from cosmic rays) lose energy by ionizing the medium through which they pass, leaving behind a wake of electron-hole pairs”. NASA Thesaurus
An aircraft's in-flight upset does not mean this was caused by a radiation induced SEU.
Where in the ATSB report was it concluded that an SEU caused the in-flight upsets?
Your post #485 is unconvincing in so many ways.
"Fault tree analysis (FTA) is a type of failure analysis in which an undesired state of a system is examined. This analysis method is mainly used in safety engineering and reliability engineering to understand how systems can fail, to identify the best ways to reduce risk and to determine (or get a feeling for) event rates of a safety accident or a particular system level (functional) failure. FTA is used in the aerospace,..FTA is also used in software engineering for debugging purposes and is closely related to cause-elimination technique used to detect bugs.
In aerospace, the more general term "system failure condition" is used for the "undesired state" / top event of the fault tree. These conditions are classified by the severity of their effects. The most severe conditions require the most extensive fault tree analysis. These system failure conditions and their classification are often previously determined in the functional hazard analysis." WIKI
Single Event Upset (SEU): Radiation-induced errors in microelectronic circuits caused when charged particles (usually from the radiation belts or from cosmic rays) lose energy by ionizing the medium through which they pass, leaving behind a wake of electron-hole pairs”. NASA Thesaurus
An aircraft's in-flight upset does not mean this was caused by a radiation induced SEU.
Where in the ATSB report was it concluded that an SEU caused the in-flight upsets?
Your post #485 is unconvincing in so many ways.
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It was considered in the investigation.
I’m just saying as a matter of how digital electronics work, it’s always a possibility.
I’ve mentioned the case of a voting machine that registered 4096 extra votes. That’s the sort of thing that can happen.
MolaKule
Staff member
It was suggested in the investigation but apparently not considered as a root cause of those in-flight upsets.
Anything can be a possibility.
I never saw that comment but was the cause a programming or IC (component) fault?
Also several instances when you could hear the FO on the CVR warning the captain that he's wrong, and the captain won't listen.
Equally heartbreaking.
4096 is too convenient. Seemed more likely to be a bit flip from 0 to 1 in the 2^12 place. It happened in some municipal election in Belgium.
In 2003, in Belgium there was an election using electronic voting machines. Mysteriously one candidate summed an excess of 4096 votes. An accurate analysis led to the official explanation that a spontaneous creation of a bit in position 13 of the memory of the computer attributed 4096 extra votes to one candidate. One of the most credited answers to this event is attributed to cosmic rays i.e.(gamma), which can filter through the atmosphere. There are cases though, with classical computers, like forensic investigations, or system recovery where such soft-errors may be helpful to gain root privileges and recover data. In this paper we show preliminary results of using radioactive sources as a mean to generate bit-flips and exploit classical electronic computation devices.
I’ve worked on stuff like that. Especially where it’s asynchronous transfers. The usual solution is to Gray code the number encoding, which will minimize errors.
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Here is a comment from a pilot's forum that I thought was interesting:
"The authors of the preliminary report would surely have known that the report as drafted would raise strong suspicions of an intentional act by one of the pilots to shut off the fuel switches. If the investigators had evidence that would indicate that it was not (or may not have been) a deliberate act (from for example the rest of the verbal exchanges between the pilots) then surely they would have included such information in the report in order to avoid such a conclusion from being drawn by the reading public. This suggests that there is no such evidence."
"The authors of the preliminary report would surely have known that the report as drafted would raise strong suspicions of an intentional act by one of the pilots to shut off the fuel switches. If the investigators had evidence that would indicate that it was not (or may not have been) a deliberate act (from for example the rest of the verbal exchanges between the pilots) then surely they would have included such information in the report in order to avoid such a conclusion from being drawn by the reading public. This suggests that there is no such evidence."
Most of us are familiar with those switches. My opinion is that they did not get bumped off. The 1 second interval is exactly what a person would deliberately do. The delay in selecting them back on tells it all.
It was known to be a smooth runway and the onboard "G" meters would have indicated a bump concurrent with "OFF" being selected.
Dan's a character, and we will leave it at that.
I don’t think the switches were activated accidentally and I don’t think they were defective (per the AD).
The only reasonable explanation for both switches being moved from RUN to CUTOFF to RUN is deliberate action by a pilot.
The “why” is going to take a while. But as I’ve previously stated, moving both switches to CUTOFF and back to RUN is also an emergency procedure.
In this case, there was quite a delay in that 'return to RUN' selection.
For most modern jets, the switch is moved to the OFF position momentarily and then immediately returned to the RUN position to initiate the channel switch. A dwell time of approximately 0.5 to 1 second in the OFF position is typical, as this is sufficient to trigger the FADEC to transfer control to the alternate channel without initiating a full engine shutdown.
MolaKule
Staff member
Are you referring to an alternate channel within the FADEC?
A short, clear video on how these switches work.
You mean, "Oh, I didn't realize I was shutting the fuel off to the engines"?
Possibly. How many times have people claimed that they didn't intentionally step on the brake or didn't intentionally step on an accelerator? Or pressed the wrong button.
I get that it sounds strange, but this whole situation just seems so bizarre. I looks like the shutdown procedure is fairly simple even with the locking mechanism.
"Positive rate, gear up"...... "Check".... "Engines to cutoff"... "Check".
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