Note that using identical hardware and software can lead to what are called common mode faults. For anything safety critical, that is still a big no no!

Hopefully, all aircraft manufacturers are better than to do such dangerous silliness as to risk single source or common mode faults for anything critical...?

Costs money to certify a part, any difference and it is a different part number. They have a duty to maximize profit. They want they to be easy to service. They want to reduce inventory. Parts bins are parts bins. Does the service manual require them to be from different sources in any given airplane? Maybe you might want to see if those computers all have the same part number. Then you can raise a stink about something before it fails and we have a disaster.

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Costs money to certify a part, any difference and it is a different part number. They have a duty to maximize profit. They want they to be easy to service. They want to reduce inventory. Parts bins are parts bins. Does the service manual require them to be from different sources in any given airplane? Maybe you might want to see if those computers all have the same part number. Then you can raise a stink about something before it fails and we have a disaster.

Gary, I'd like to explore that 'Fiduciary duty to maximize profit' a bit more.

I accept that it's a common, simplistic, statement, probably taught in week zero of business school. But since when? What is the legal authority? When was the bill passed? Who by? And is it accepted by all, further up the business school syllabus - perhaps at MBA level and above?

I assume that you're familiar with the US Business Roundtable report from earlier this week: https://opportunity.businessroundtable.org/ourcommitment/

The New York Times commented:

Nearly 200 chief executives, including the leaders of Apple, Pepsi and Walmart [edit, RH: and also including Dennis A. Muilenburg, The Boeing Company], tried on Monday to redefine the role of business in society — and how companies are perceived by an increasingly skeptical public.

Breaking with decades of long-held corporate orthodoxy, the Business Roundtable issued a statement on “the purpose of a corporation,” arguing that companies should no longer advance only the interests of shareholders. Instead, the group said, they must also invest in their employees, protect the environment and deal fairly and ethically with their suppliers.

“While each of our individual companies serves its own corporate purpose, we share a fundamental commitment to all of our stakeholders,” the group, a lobbying organization that represents many of America’s largest companies, said in a statement. “We commit to deliver value to all of them, for the future success of our companies, our communities and our country.”

My own preferred local UK paper, The Guardian, went further:

Milton Friedman will be spinning in his grave at the heresy perpetrated by the US Business Roundtable. For the thick end of five decades US capitalism has been run along Friedmanite lines – namely that businesses are there to make money for their shareholders. No charitable giving, no diversity awareness. No green audits. Just making money. Period.

Now some of the highest paid on the planet have appeared to ditch the idea of shareholder primacy. Sure, they say, shareholders matter but so do a range of other stakeholders: customers, employees, suppliers and communities. Workers must be treated with dignity and respect. Businesses will be run sustainably in order to protect the environment.

If it’s for real, this represents quite a sea change. Friedman’s essay for the New York Times in 1970 was hugely influential and has governed boardroom behaviour ever since. The whole “greed is good” philosophy that flowered in the 1980s was based on the economist’s idea that the sole task of executives was to enrich shareholders provided they played by the rules.

But Friedman also said that playing by the rules meant more than obeying the law: it meant conforming to ethical custom. And in recent years there has been a shift in what the public considers to be right and wrong. The fact that CEOs have seen their pay rocket while average wages have stagnated is part of the story, but so too is the way in which profit-maximising companies have hollowed out communities by moving production offshore.

and so on.

Could it really be true that 'Fiduciary Duty' (in its present form) derives, not from statute, but from a 1970 newspaper article by Milton Friedman? That would put a different perspective on things...

That thread on "quora" does pose an interesting hypothesis, but it also shows an alarming lack of understanding of who the ARINC network behaves.
The ARINC protocol has a very high degree of bit-level error detection built-in, such that bit-level errors as described are detected and "trapped" before they can "do any damage" by the erroneous data being used. If the ARINC bus was "faulty" it wouldn't be "selective" in which data it was corrupting, it would be just about every data stream, and most of the time.
What cannot be said (at least by me) is if it was the mechanical bit or the electronic bit of the AoA probe failed, but my guess, based on previous incidents where these probes have failed (across multiple aircraft manufacturers) it was more probably the mechanical part.
And what of the Flight Data Recorder - this collects data from all over the aircraft, particularly the outputs from the various "flight status sensors", including the AoA probes - and that data showed that the AoA sensors were in disagreement for both aircraft.
And so we go back to the question that still lurks around - why did Boeing decide to use only one of the two probes at any one time - cost bare;y comes into that as both probes and their associated infrastructure have to be maintained and a robust voting system is actually very cheap (possibly cheaper that the side-swapping logic that they used).

---

Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Richard, while there is no specific statute to point to, there are the many cases where shareholders have sued the company. These decisions form the basis of the law (case law) via stare dices. Many of these suits were brought in the time right after the publication of Mr. Friedman's essay. Juries, judges and lawyers are not insulated from public opinion.

There is and always has been significant wiggle room for boards to decide that an action may be harmful long term even if profitable short term. There is always the intangible value of the brand names. There are the costs which might be born for not operating clean and then being forced at a later date to clean up. It seems as if many executives have woken up to the fact that at some future date their corporation will be forced to bear costs for their decision on how to operate today. Depending on how you value these future costs, doing things clean today may maximize profit to the shareholder. One need only look at asbestos litigation as an example of doing something that was not realized as harmful and what the future costs can become. The other end may be hiring undocumented persons and the low fines and near zero prosecutions for doing so. When public opinion changes, values change.

I don't actually think that profit, profit, profit is gone, just a difference in time horizons on how to measure profit and how to value the intangible brand name asset.

I think that means that the people at the top of the greasy pole have to take responsibility for the decisions they make. In that formulation, there's enough wriggle room to cover just about anything. They can't blame force majeur - i.e. fiduciary duty - for forcing them into a position that they were unwilling to espouse voluntarily.

However "murder" trumps everything else - even the duty to make money.

---

Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

However "murder" trumps everything else - even the duty to make money.

Unfortunately, those dumb enough and psychopathic greedy enough to try that, are also dumb enough to believe they can still cheat their way to run off with the money...



All in our only one world,
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

Note that using identical hardware and software can lead to what are called common mode faults. For anything safety critical, that is still a big no no!

Hopefully, all aircraft manufacturers are better than to do such dangerous silliness as to risk single source or common mode faults for anything critical...?

Costs money to certify a part, any difference and it is a different part number. They have a duty to maximize profit. They want they to be easy to service. They want to reduce inventory. Parts bins are parts bins. Does the service manual require them to be from different sources in any given airplane? Maybe you might want to see if those computers all have the same part number. Then you can raise a stink about something before it fails and we have a disaster.

Checking for what Airbus and Boeing do for the fly-by-wire systems on the Airbus A320 and the Boeing 777, see this comparison:

pdf: APPROACHES TO ASSURE SAFETY IN FLY-BY-WIRE SYSTEMS: AIRBUS VS. BOEING


Very interesting reading and interesting approaches. There's a lot of careful consideration needed there for the potential failure modes and for the overall complexity/robustness/fragility...

Also, there is a lot of reliance made on the actual implementation for all that to work flawlessly... Back to the old game of Peer Review, (thorough/exhaustive) Test, and Certification?


So... For what Boeing implemented for themselves for their Boeing 777, why again was that not similarly done for Boeing's 737 MAX fly-by-wire parts of the avionics?

All in our only one world,
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

Here's a recent YouTube interview update on the Boeing 737 Max:


"YouTube: Boeing 737 Max 8 Won't Fly Till Early 2020" | Peter Greenberg - Travel Expert


The comments in there sound to be somewhat damning of the FAA including "The FAA [mandate/legislation] ... has to change".


All in our only one world,
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

... So... What is/was this mystery flaps/flight-stabilization fault?...

Here's a worrying Boeing 737 MAX mystery that I've not been able to find anything further about on various web searches:


Additional Software Problem Found In Boeing 737 Max Control System

Boeing confirmed to The Washington Post that it had found a second software problem that the Federal Aviation Administration has ordered fixed - separate from the anti-stall system under investigation in the two crashes...

That additional problem pertains to software affecting flaps and other flight stabilization hardware and is therefore classified as critical to flight safety, said two officials who spoke on condition of anonymity to discuss the ongoing probe.

The realization of a second software problem explains why the timeline that Boeing projected publicly last week for getting hundreds of the aircraft airborne again has slipped...




So... What is that second flight software fault that was found? And in what way critical to flight? And how many passenger flights has that software been flying with what real risk??

Anyone able to sleuth further details?

So far, I've found... Nothing.

Whatever it is, it's being kept 'secret' or at least unpublished.

However, this article might give a clue:


How Software Can Make an Airplane Crash

... However, not all systems in the Boeing 737 Max series are designed for pilot override. The airplane’s flaps, for example, use a new fly-by-wire system that controls them automatically for most stages of a flight. Another fly-by-wire system is the MCAS (Maneuvering Characteristics Augmentation System), which adjusts the position of the aircraft’s horizontal stabilizer to prevent a stall...



So... The flaps on the Boeing 737 Max are fully automated fly-by-wire?

I wonder if there is any redundant operation/safety for those? Also, ISTR elsewhere that there have been pilot complaints of the autopilot dropping out and of loss of height when the flaps have been adjusted...?

All connected? Any definite details anywhere?


All in our only one world,
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

Meanwhile, Boeing pushes ahead while the rest of the world play catch-up:


FAA Could Operate Boeing 737 MAX Certification Flights In October

The Federal Aviation Administration (FAA) is on target to start conducting certification flights for the Boeing 737 MAX starting in October.

Knowing what we know now, the 737 MAX should never have been certified to fly in the first place.

Now after months of extensive testing, Bloomberg reports that the 737 MAX will undergo certification flights by the FAA in the next few weeks...

... To ensure all safety aspects of the 737 MAX have been addressed, the FAA is looking to use test pilots who have had little or no experience flying the Boeing 737 family of aircraft...

... The entire process of grounding the 737 MAX has been a lesson in what happens when companies cut corners to put profit over safety...

... If after recertification something else should go wrong with the 737 MAX or god forbid another accident, Boeing will have a hard time escaping the media’s attention...



Russian firm sues Boeing over Max jet, says defects hidden

A Russian aircraft leasing company that ordered 35 Boeing Max jets is suing the U.S. aircraft maker and seeking to cancel the deal, accusing Boeing of hiding defects in the plane that was grounded after two deadly crashes...

... claims that Boeing committed fraud and breach of contract and was negligent in how it designed and built the plane and convinced the Federal Aviation Administration to approve it...



FAA Cautions Airlines on Maintenance of Sensors that Were Key to 737 Max Crashes

Following two deadly crashes of the Boeing 737 MAX, both of which were initiated by a faulty reading from a single angle of attack sensor, the Federal Aviation Administration (FAA) has cautioned airlines, aircraft-maintenance companies and manufacturers that the sensors are vulnerable to damage and must be carefully maintained...

... But even if the updated MCAS is no longer a danger, faulty AOA sensors will have to be a separate safety focus because the measurement from these sensors is fed into the flight computer and used to calculate other parameters.

Boeing’s bulletin to airlines a week after the Lion Air crash told pilots that on the MAX “an erroneous AOA can cause some or all of the following indications and effects”:

Continuous or intermittent stick shaker (which means the pilot’s control column shakes alarmingly to warn of a possible stall);
An indication that the aircraft is approaching its minimum speed limit;
Increasing nose down control forces;
Inability to engage autopilot;
Automatic disengagement of autopilot;
An alert that the Indicated Air Speed sensors disagree;
An alert that the altitude sensors disagree;
An alert that the AOA sensors disagree;
A light warning of a difference in hydraulic pressure applied to the control columns of the captain and the first officer.



Confusing or what?!

And really? The media are more effective safety overseers than Boeing and the FAA combined?!!


All in our only one world,
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

Meanwhile, Boeing pushes ahead while the rest of the world play catch-up:


FAA Could Operate Boeing 737 MAX Certification Flights In October

The Federal Aviation Administration (FAA) is on target to start conducting certification flights for the Boeing 737 MAX starting in October.

Knowing what we know now, the 737 MAX should never have been certified to fly in the first place.

Now after months of extensive testing, Bloomberg reports that the 737 MAX will undergo certification flights by the FAA in the next few weeks...

... To ensure all safety aspects of the 737 MAX have been addressed, the FAA is looking to use test pilots who have had little or no experience flying the Boeing 737 family of aircraft...

... The entire process of grounding the 737 MAX has been a lesson in what happens when companies cut corners to put profit over safety...

... If after recertification something else should go wrong with the 737 MAX or god forbid another accident, Boeing will have a hard time escaping the media’s attention...

Prof Simon gives a brief summary update with a few questions/concerns:

YouTube: Will Boeing Max 8 fly again ? - Prof Simon

Boeing max 8 update. 3 new news items about the max 8. FAA certification, Training and international approval to fly...



All in our only one world,
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

Finally some truth and not this MCAS screaming ...

FAA Cautions Airlines on Maintenance of Sensors that Were Key to 737 Max Crashes

https://www.aviationpros.com/aircraft/commercial-airline/news/21093618/faa-cautions-airlines-on-maintenance-of-sensors-that-were-key-to-737-max-crashes wrote:

The tragic sequence of events on both flights began when a false reading from an AOA sensor

On the Lion Air jet, the sensor had given false readings on previous flights and at least one AOA vane was replaced. On the crash flight, the AOA vane feeding MCAS gave a false reading, off by 20 degrees from the vane on the other side, even as the jet taxied on the ground. The faulty vane maintained that difference throughout the 11-minute flight.

On the Ethiopian Airlines jet, the AOA vane feeding MCAS was reading accurately until just after take-off, when suddenly it veered off by 75 degrees, an impossible reading. This suggests the vane may have been sheared off by a bird strike.

So on Lion air it is obvious the plane never should have taken off. Maintenance crew and Aircrew 100% at fault for allowing it.

Ethiopian, this sounds like a real accident, act of god.

Now the question is, how base are lawyers and how bad can they make Boeing's insurance company bleed?

On the Ethiopian Airlines jet, the AOA vane feeding MCAS was reading accurately until just after take-off, when suddenly it veered off by 75 degrees, an impossible reading. This suggests the vane may have been sheared off by a bird strike.

The bird strike theory isn't news, it was first reported in April, and discussed a few weeks later after it reached the main stream media. And only leads to one question.

Why does the 737Max fight control system only use one AOA sensor?

Why does the 737Max fight control system only use one AOA sensor?

No. There are two AOA sensors, one on the port and one on the starboard. And both are used. Problem occur of course if they mismatch. It seems to me that MCAS has problem to handle that situation.

Why does the 737Max fight control system only use one AOA sensor?

No. There are two AOA sensors, one on the port and one on the starboard.

It might have two, but only one is in use. And without buying an add-on there is no obvious indication to the pilots that the two sensors disagree.

Why does the 737Max fight control system only use one AOA sensor?

No. There are two AOA sensors, one on the port and one on the starboard.

It might have two, but only one is in use. And without buying an add-on there is no obvious indication to the pilots that the two sensors disagree.

Oh. Indicators are extra. Oh dear...

Why does the 737Max fight control system only use one AOA sensor?

No. There are two AOA sensors, one on the port and one on the starboard.

It might have two, but only one is in use. And without buying an add-on there is no obvious indication to the pilots that the two sensors disagree.

Oh. Indicators are extra. Oh dear...

Read all about it https://www.businessinsider.com/boeing-angle-of-attack-disagree-alert-system-optional-737-max-2019-5?r=US&IR=T

On the Ethiopian Airlines jet, the AOA vane feeding MCAS was reading accurately until just after take-off, when suddenly it veered off by 75 degrees, an impossible reading. This suggests the vane may have been sheared off by a bird strike.

The bird strike theory isn't news, it was first reported in April, and discussed a few weeks later after it reached the main stream media. And only leads to one question.

Why does the 737Max fight control system only use one AOA sensor?

You mean why did Boeing waste money and put a second sensor on the plane? Or is that second sensor used by other software and our prime source hasn't reported that?

(or is your question how do you choose which of two inputs to trust in real time and be assured you are picking correctly and that at least one is correct and can be trusted?)

(or is your question how do you choose which of two inputs to trust in real time and be assured you are picking correctly and that at least one is correct and can be trusted?)

That's why I always went for three sensors even when it was only protecting the equipment. Overall when the total equipment cost is in the millions, three sensors and the simple electronics needed to detect the odd one out rarely comes into the equation.