kayik wrote:

zippy wrote:

Revelation wrote:

Saying that somebody was killed by negligence is a serious accusation, one that should not be made casually and without the kind of proof that would be needed in a court room, IMO.

There's quite a significant difference between what a layperson refers to as negligence and what the court deems criminal negligence. Even then it's not like this discussion is happening in a vacuum. So far:

- Boeing has admitted that they knew the primary flight displays were faulty and had no intent on notifying the FAA, the airlines, correcting the documentation, or submitting a fix until 2020 (until the Lion Air crash)
- A Boeing engineer went on the record (60 Minutes Australia) stating that MCAS relied on only one alpha vane at a time to avoid additional scrutiny.
- Boeing knowingly modified MCAS to dramatically increase its authority after it was certified by the FAA (presumably after testing it about as much as they did the PFDs)
- Boeing knowingly signed off on simulators that not only didn't implement MCAS but didn't maintain realistic force on the trim wheels

These were deliberate actions, not casual mistakes.

Yes, I would like to know whether these are mistakes or negligence or whatever you name it. What would a jury think if it goes there?

Several articles in the news today stating that although Boeing knew about the faulty light sensor before the Lion crash they made a decision to fix it in 2020.

Then after the Lion crash they started fixing it immediately

You have to argue that this was a negligent decision both before and after Lion

They should have grounded the planes and fixed them before Lion

Once Lion crashed and they decided to bring forward the fix they should have grounded then

When Ethiopia crashed and they argued against grounding its actually bordering on the ridiculous

Some awful decisions have been taken. Negligent would be a fair description IMO

Trying to say the light wasn't crucial but then bringing forward work on it and now accepting that was a mistake is going to be very hard for lawyers to defend

It certainly doesn't suggest a safety first culture in Boeing and it's certainly open to negligence accusations

On the subject of timelines, it would be prudent to remind the audience of the track record Boeing holds in this regard. I'm specifically thinking the 787, which brings us to the logical conclusion that the time lines offered by Boeing, are mainly for the consumption of Wall Street and protection of the share price.

The inherent problem they face is, the more the twist the arm of the FAA to expedite the process, the more trust in the FAA will be lost. And I'm fairly certain TC, CAAC and EASA will make sure they get this absolutely right before lifting the grounding, possibly to the extent of an almost complete re-certification process. And who knows which, and how many, skeletons might have dropped out of the closet by the time they're done.

Summer of 2020 does not sound far fetched.

https://www.reuters.com/article/us-boei ... SKCN1T8284

Reuters today. When the warning light story first came out - the assumption was that it was just a mistake missed by Boeing that the warning light wasn't working on Max planes

Letters have shown that they had full knowledge of the defect in 2017 and CHOSE to deal fixing it til 2020

After the first crash they adjusted their decision

They have admitted their decision making was at fault

This is so poor from Boeing and so difficult for them to explain

100 per cent they cannot claim to be an organisation that puts safety first for their passengers

So poor and such bad reading

planecane wrote:

mjoelnir wrote:

kalvado wrote:

For one, I would say exact same thing if Boeing, Airbus, Toyota, Ford, or Sukhoi are involved: engineer making an honest mistake in design, which was not caught in test, can face a lot of professional consequences - but there should be no criminal consequences. Same with pilots, who survive their crashes: professionally things may be bad, but criminal action is not warranted. Same with doctors. Probably a bunch of other high responsibility professions.
People can make mistakes, system should be designed to minimize effect of those mistakes, but mistakes will happen, and scaring people away from those professions will only make things worse in a long run.
Money - reasonable measure. Those come from customers anyway, so everyone eventually looses, though
Formal qualification and future professional activities - maybe, case-by-case. Prison - no point.

Engineers are responsible for their design. Negligence has put engineers into prison before. Why should aircraft engineers get a special dispensation? Anyway we are not only talking about engineers.

In what country have engineers gone to prison and what did they do? I am an engineer in the USA and I was never warned of possible criminal charges for making a mistake.

Can happen in the UK amongst other places. Designers also can be jailed for bad designs that cause deaths.. Google is your friend..

jomur wrote:

planecane wrote:

mjoelnir wrote:

Engineers are responsible for their design. Negligence has put engineers into prison before. Why should aircraft engineers get a special dispensation? Anyway we are not only talking about engineers.

In what country have engineers gone to prison and what did they do? I am an engineer in the USA and I was never warned of possible criminal charges for making a mistake.

Can happen in the UK amongst other places. Designers also can be jailed for bad designs that cause deaths.. Google is your friend..

In this case I don't think this is an engineers mistake that would lead to prosecution

I think the potential negligence is not correcting the mistake once they became aware

That's a top level management decision mistake (already an accepted mistake by Boeing) and will take a hell of a lot of explaining away

It's very hard to defend in view of what happened and the timelines

zippy wrote:

planecane wrote:

mjoelnir wrote:

Killing somebody by negligence is also a crime. Why do so many posters here expect others to tiptoe around the issue, just because Boeing is involved?

Please find the federal statute in the USA that says this. I can't find it and no State would have jurisdiction. If it isn't a federal law, even if the country where the crash occurred charged Boeing or a person at Boeing, the US government would not extradited anybody.

Even in the states that have it as a law, the negligence would have to be extreme to lead to a criminal negligence charge, far beyond anything Boeing did based on current information. Doctors are not arrested every time a mistake leads to a death.

So this took me under a minute to find. I'm not sure why you couldn't.

https://www.law.cornell.edu/uscode/text/18/1112

Manslaughter is the unlawful killing of a human being without malice. It is of two kinds:
Voluntary—Upon a sudden quarrel or heat of passion.

Involuntary—In the commission of an unlawful act not amounting to a felony, or in the commission in an unlawful manner, or without due caution and circumspection, of a lawful act which might produce death.

The DoJ has a more in depth analysis of when homicide is a federal crime:

https://www.justice.gov/sites/default/f ... ab6001.pdf

None of that applies to Boeing (in a statutory sense) in this case. People are trying to say they could be guilty of homicide due to criminal negligence. As far as I can find (and the references you cite don't say otherwise), there is no FEDERAL statute in the USA that provides for that type of charge (or anything like it).

jomur wrote:

planecane wrote:

mjoelnir wrote:

Engineers are responsible for their design. Negligence has put engineers into prison before. Why should aircraft engineers get a special dispensation? Anyway we are not only talking about engineers.

In what country have engineers gone to prison and what did they do? I am an engineer in the USA and I was never warned of possible criminal charges for making a mistake.

Can happen in the UK amongst other places. Designers also can be jailed for bad designs that cause deaths.. Google is your friend..

Last I checked, Boeing is in the USA, not the UK. Therefore, US Federal law would apply. Extradition treaties will only provide for extradition if the same crime exists in the US code. Perhaps Boeing or a Boeing employee or executive could be charged or convicted in another country but they would never be extradited to face prosecution or incarceration.

Interested wrote:

jomur wrote:

planecane wrote:

In what country have engineers gone to prison and what did they do? I am an engineer in the USA and I was never warned of possible criminal charges for making a mistake.

Can happen in the UK amongst other places. Designers also can be jailed for bad designs that cause deaths.. Google is your friend..

In this case I don't think this is an engineers mistake that would lead to prosecution

I think the potential negligence is not correcting the mistake once they became aware

That's a top level management decision mistake (already an accepted mistake by Boeing) and will take a hell of a lot of explaining away

It's very hard to defend in view of what happened and the timelines

Yes, however it would be negligence leading to civil liability, NOT criminal charges in the USA.

Interested wrote:

https://www.reuters.com/article/us-boeing-737-idUSKCN1T8284

Reuters today. When the warning light story first came out - the assumption was that it was just a mistake missed by Boeing that the warning light wasn't working on Max planes

Letters have shown that they had full knowledge of the defect in 2017 and CHOSE to deal fixing it til 2020

After the first crash they adjusted their decision

They have admitted their decision making was at fault

This is so poor from Boeing and so difficult for them to explain

100 per cent they cannot claim to be an organisation that puts safety first for their passengers

So poor and such bad reading

The AoA disagree warning (to nitpick wasn't a light) issue "looks" bad and will certainly be used against Boeing in law suits however, in reality, it has nothing to do with the two crashes.

The Lion Air crew had no idea about MCAS so having AoA disagree appear on the PFD would have meant nothing to them. The ET crew appears to have recognized what was going on so the warning likely wouldn't have changed their actions either.

Knowing the alert was missing, Boeing shouldn't have included AoA disagree as something that can be seen during an MCAS runaway event in the EAD. They also should have alerted the FAA upon discovery that the alert was missing so the FAA could have done the safety review. However, before the Lion Air crash they probably would have reached the same conclusion as Boeing.

jomur wrote:

planecane wrote:

mjoelnir wrote:

Engineers are responsible for their design. Negligence has put engineers into prison before. Why should aircraft engineers get a special dispensation? Anyway we are not only talking about engineers.

In what country have engineers gone to prison and what did they do? I am an engineer in the USA and I was never warned of possible criminal charges for making a mistake.

Can happen in the UK amongst other places. Designers also can be jailed for bad designs that cause deaths.. Google is your friend..

AFAIK it is possible in most countries. I have been dealing with investigations against employees in the past. I was just dealing with the technical investigation, so don’t pin me down on the legalities. From what I understand it can happen if it is unequivocally proven that the employer took sufficient measures for prevention, and the employee actively and knowingly circumvented these measures.

But I think the burden of proof is quite heavy. For instance in one of these cases an employee ignored procedures while assempling a component leading to a pretty bad accident. However in the end they could not make a case. The argument was: While the employee knowingly bypassed a procedure, the reason for the procedure was insufficiently made aware to her and the company was putting a enormous pressure on her to make a deadline, which could not be met without cutting corners.

I guess it is the same for designs. You can always make a mistake. The company should catch that mistake so they are normally responsible. But if you actively hide the mistake from your company, then you are personally responsible.

planecane wrote:

None of that applies to Boeing (in a statutory sense) in this case. People are trying to say they could be guilty of homicide due to criminal negligence. As far as I can find (and the references you cite don't say otherwise), there is no FEDERAL statute in the USA that provides for that type of charge (or anything like it).

I quite literally cited the federal code that defines criminally negligent homicide as involuntary manslaughter. I'd suggest going back and reading it again. And, yes, the federal government does pursue criminally negligent homicide charges from time to time (e.g. the M.T. Virgo incident).

planecane wrote:

Interested wrote:

https://www.reuters.com/article/us-boeing-737-idUSKCN1T8284

Reuters today. When the warning light story first came out - the assumption was that it was just a mistake missed by Boeing that the warning light wasn't working on Max planes

Letters have shown that they had full knowledge of the defect in 2017 and CHOSE to deal fixing it til 2020

After the first crash they adjusted their decision

They have admitted their decision making was at fault

This is so poor from Boeing and so difficult for them to explain

100 per cent they cannot claim to be an organisation that puts safety first for their passengers

So poor and such bad reading

The AoA disagree warning (to nitpick wasn't a light) issue "looks" bad and will certainly be used against Boeing in law suits however, in reality, it has nothing to do with the two crashes.

The Lion Air crew had no idea about MCAS so having AoA disagree appear on the PFD would have meant nothing to them. The ET crew appears to have recognized what was going on so the warning likely wouldn't have changed their actions either.

Knowing the alert was missing, Boeing shouldn't have included AoA disagree as something that can be seen during an MCAS runaway event in the EAD. They also should have alerted the FAA upon discovery that the alert was missing so the FAA could have done the safety review. However, before the Lion Air crash they probably would have reached the same conclusion as Boeing.

Alternative opinion.
I think you dismiss the situation too easily. I would suspect had AOA DISAGREE been displayed on JT043, it is likely the pilot would have recorded it, as well as IAS and Altitude, such that MX would have to address it prior to JT610 getting into the air and may well have resulted in MX taking the correct action. If AOA DISAGREE had been displayed in ET302, it might have coloured their appreciation of the situation and what subsequent actions they took.

Ray

DocLightning wrote:

morrisond wrote:

They make tons of cash on the 787 program, then there are parts and Services and Boeing defense and they could always continue production of the

morrisond wrote:

They make tons of cash on the 787 program, then there are parts and Services and Boeing defense and they could always continue production of the NG to bridge the gap. The 767 Program is probably cash flow positive as well - the Tanker Costs are already sunk and written off.

Boeing Commercial does not make money from Boeing Defense. Boeing Corporation does, of course and they could use that money to subsidize BCA. However, that would mean that BCA is not self-sustaining. The 787 program is cashflow-positive and has been since 2016, but the program has still not recouped the initial development costs and is nowhere near doing so. (1) The most optimistic projection is that if Boeing can negotiate prices aggressively and minimize future production costs, they may be able to maintain a 25% margin on each frame, which could zero-out the balance by the end of the program and might even turn a very small (a few million) overall program balance.

The 767 program, while now a defense product, is likely profitable for BCA, as is the 777, although the 777X program is of course running at a net loss because they haven't delivered any frames yet. Fortunately, that program doesn't seem to have run into any major snags yet.

(1)https://seekingalpha.com/article/4190295-boeing-787-going-zero?page=2 (Note: free registration required)

If the Defense side was losing money for some time I'm sure Boeing Commercial would support it. I'm pretty sure when Boeing borrows Corporate Money it is based on the whole companies ability to repay.

From a cash flow standpoint - which is the critical thing while the MAX is grounded - it doesn't matter how much of the 787 Deferred cost is being repaid as that is just an accounting entry which is already paid for in the balance sheet - Boeing owes it to itself.

The 787 Program itself will provide enough actual cash flow (Money received from Airlines on Delivery) over and above cash production cost when frames are delivered to probably put $4-5billion on Boeing's Cash Flow line this year with about 168 Deliveries.

Literally all the MAX grounding does for Cash flow is remove the cash flow Boeing would have used to fund Share repurchases - less the inventory interest costs of not being able to deliver completed frames.

With an $500B backlog - if they don't have enough cash to cover 300-400 undelivered frames - it won't be that difficult to get financing to cover that - assuming the credit lines don't exist already.

The one big caveat - is if the FAA mandates a Frame redesign or something (which I don't think is needed and so far the FAA has said nothing about) which could take a few years - but then Boeing just shuts the program (and moves onto NSA production in 5-6 years probably at a new non-union greenfield site) or reverts to 737NG production at very small profit margins and smaller numbers to keep the workers in place and not lose that infrastructure.

The above is highly unlikely though and we should hear within a month or so what the final solution will be.

Boeing will still be here 12 months from now.

Anyone interested in when the storage of the MAX a/c start affecting the other programs that need the space, in particular the 787?
Thankfully they have another location to produce the 787 that does not have space being taken up by the MAX a/c., can they increase the rate there, are the production locations customer specific?
If the 787 is to continue to provide the cash flow, it has to continue flow smoothly, it does need some storage space of its own.

planecane wrote:

Interested wrote:

https://www.reuters.com/article/us-boeing-737-idUSKCN1T8284

Reuters today. When the warning light story first came out - the assumption was that it was just a mistake missed by Boeing that the warning light wasn't working on Max planes

Letters have shown that they had full knowledge of the defect in 2017 and CHOSE to deal fixing it til 2020

After the first crash they adjusted their decision

They have admitted their decision making was at fault

This is so poor from Boeing and so difficult for them to explain

100 per cent they cannot claim to be an organisation that puts safety first for their passengers

So poor and such bad reading

The AoA disagree warning (to nitpick wasn't a light) issue "looks" bad and will certainly be used against Boeing in law suits however, in reality, it has nothing to do with the two crashes.

The Lion Air crew had no idea about MCAS so having AoA disagree appear on the PFD would have meant nothing to them. The ET crew appears to have recognized what was going on so the warning likely wouldn't have changed their actions either.

Knowing the alert was missing, Boeing shouldn't have included AoA disagree as something that can be seen during an MCAS runaway event in the EAD. They also should have alerted the FAA upon discovery that the alert was missing so the FAA could have done the safety review. However, before the Lion Air crash they probably would have reached the same conclusion as Boeing.

I've seen a report a couple of weeks ago suggesting the warning light would have allowed the Ethiopian pilots to recognise and identify their problem earlier

If that's true then it's end of argument about whether or not it would have helped them.

morrisond wrote:

DocLightning wrote:

morrisond wrote:

They make tons of cash on the 787 program, then there are parts and Services and Boeing defense and they could always continue production of the

morrisond wrote:

They make tons of cash on the 787 program, then there are parts and Services and Boeing defense and they could always continue production of the NG to bridge the gap. The 767 Program is probably cash flow positive as well - the Tanker Costs are already sunk and written off.

Boeing Commercial does not make money from Boeing Defense. Boeing Corporation does, of course and they could use that money to subsidize BCA. However, that would mean that BCA is not self-sustaining. The 787 program is cashflow-positive and has been since 2016, but the program has still not recouped the initial development costs and is nowhere near doing so. (1) The most optimistic projection is that if Boeing can negotiate prices aggressively and minimize future production costs, they may be able to maintain a 25% margin on each frame, which could zero-out the balance by the end of the program and might even turn a very small (a few million) overall program balance.

The 767 program, while now a defense product, is likely profitable for BCA, as is the 777, although the 777X program is of course running at a net loss because they haven't delivered any frames yet. Fortunately, that program doesn't seem to have run into any major snags yet.

(1)https://seekingalpha.com/article/4190295-boeing-787-going-zero?page=2 (Note: free registration required)

If the Defense side was losing money for some time I'm sure Boeing Commercial would support it. I'm pretty sure when Boeing borrows Corporate Money it is based on the whole companies ability to repay.

From a cash flow standpoint - which is the critical thing while the MAX is grounded - it doesn't matter how much of the 787 Deferred cost is being repaid as that is just an accounting entry which is already paid for in the balance sheet - Boeing owes it to itself.

The 787 Program itself will provide enough actual cash flow (Money received from Airlines on Delivery) over and above cash production cost when frames are delivered to probably put $4-5billion on Boeing's Cash Flow line this year with about 168 Deliveries.

Literally all the MAX grounding does for Cash flow is remove the cash flow Boeing would have used to fund Share repurchases - less the inventory interest costs of not being able to deliver completed frames.

With an $500B backlog - if they don't have enough cash to cover 300-400 undelivered frames - it won't be that difficult to get financing to cover that - assuming the credit lines don't exist already.

The one big caveat - is if the FAA mandates a Frame redesign or something (which I don't think is needed and so far the FAA has said nothing about) which could take a few years - but then Boeing just shuts the program (and moves onto NSA production in 5-6 years probably at a new non-union greenfield site) or reverts to 737NG production at very small profit margins and smaller numbers to keep the workers in place and not lose that infrastructure.

The above is highly unlikely though and we should hear within a month or so what the final solution will be.

Boeing will still be here 12 months from now.

I completely agree with that Boeing will still be there, not only in 12 months, but years from now. But meanwhile there will be tough times ahead.

I do not agree that the deferred cost is just an accounting entry, than cash flow would also be just an accounting entry.

The deferred cost are either profits declared, but not yet made, or losses made but not yet declared. Take your pick.
The deferred cost also influence declared inventories, as they are parked as part of Boeing's inventory.
Additionally to that, Boeing, or better its shareholders, have no equity.

The above is no problem in good times, but can raise its ugly head, when the going gets tough

jomur wrote:

planecane wrote:

mjoelnir wrote:

Engineers are responsible for their design. Negligence has put engineers into prison before. Why should aircraft engineers get a special dispensation? Anyway we are not only talking about engineers.

In what country have engineers gone to prison and what did they do? I am an engineer in the USA and I was never warned of possible criminal charges for making a mistake.

Can happen in the UK amongst other places. Designers also can be jailed for bad designs that cause deaths.. Google is your friend..

Absolutely. That is the whole purpose of the Authority process I described a month or so ago in today's regulatory environment..
Each system will have a Technical Authority (usually a very senior Engineer - Team Leader or Manager)
The Platform as an integrated article has a Technical Authority - usually the Programme Chief Engineer
They will all have Letters of Delegated Authority from the Engineering Director (or Exec VP Engineering in the USA)

The people with those Authorites WILL go to prison for Criminal Negligence if it is proved. no-one should be in any doubt about that.
I have seen it happen here in the UK, and our Chief Engineers are absolutely aware that they will face prison sentences if found guilty.
In my current role as the Principal Manufacturing Engineering lead on a (very) major programme (with direct links to a US counterpart by the way) I also have a Letter of Delegated Authority signed by both the Engineering Director and Manufacturing Director, which clearly explains how my liability dovetails with that of the Engineers

@Planecane - if you have never been advised of this in an Engineering role, it implies that you have never held a formally delegated Authority.
In which case you have nothing to worry about when things go belly up.

But the "Technical Authorites" associated with the MAX will absolutely have the risk of a prison sentence if they are found not to have discharged that Authority in an appropriate manner. As an aside, the FAA screwing up will NOT absolve them of that responsibility
That is my opinion, but in all honesty, I don't really think it is an "opinion", for what it's worth.
If you can show me it is different in this case I will happily demur

Rgds

DenverTed wrote:

OldAeroGuy wrote:

The intent is to
obtain enough data to determine the stall speed at an entry rate not exceeding 1.0 knot/second.

I take it that means a deceleration of less than 1.0 knot/second to stall, during which the control pressure must increase. So the righting force curve went flat or up on the MAX in this zone?

You must obtain enough data to correct the stall speed to an entry rate of 1.0 knot/second. Some stalls will have an entry rate greater than 1.0 knot/sec and some will have less.

The stability level does not have to be flat or go unstable to fail 25.203. Here are some hypothetical cases:

Case 1 - Passes 25.203
AoA - Stick Force - lbs
4 - 0 (trimmed)
5 - 5
6 - 10
7 - 15
8 - 20
9 - 25
10 - 31
11 - 37 (stall warning)
12 - 39 (stall)
A stall of this type would be indicative of stall starting on the inboard wing. The change in stick force gradient after stall warning is acceptable.

Case 2 - Fails 25.203
AoA - Stick Force - lbs
4 - 0 (trimmed)
5 - 5
6 - 10
7 - 15
8 - 20
9 - 25
10 - 28
11 - 30 (stall warning)
12 - 32 (stall)
A stall of this type would be indicative of stall starting on the outboard wing. The configuration is stable throughout the stall as stick force must be increased to stall the airplane. The change in gradient after 9 deg AoA causes the airplane to fail 25.203. This is the type of stall handling is typically called "stick lightening". The 737 MAX probably has this type of stall approach behavior and is why MCAS was added.

Case 3 - Larger H. Stab, Fails 25.203
AoA - Stick Force - lbs
4 - 0 (trimmed)
5 - 6
6 - 12
7 - 18
8 - 24
9 - 30
10 - 33
11 - 36 (stall warning)
12 - 38(stall)
The larger h. stab increases overall stability and stick forces but "stick lightening" due to outboard wing stall is still present and the change in stick force gradient flunks 25.203.

Case 4 - MCAS added, Passes 25.203
AoA - Stick Force - lbs
4 - 0 (trimmed)
5 - 5
6 - 10
7 - 15
8 - 20
9 - 25
10 - 30 (MCAS activates)
11 - 36 (stall warning)
12 - 40 (stall)
A properly implemented MCAS system is not a bad idea. Similar concepts may be imbedded in many FBW airplanes and invisible during normal operation.

DenverTed wrote:

OldAeroGuy wrote:

I've seen it suggested that enlarging the h. stab would solve the problem. This isn't the case.

I assume the limiting case/configuration is the stab trim at nose up limit of trim switch, and the righting moment versus AOA curve as the elevator is used to enter a stall according to the parameters of the test.
I suppose if the curve was negative, a larger stab should work and make it more negative, increase the force on the column. If the curve has gone flat or up, something else is going on to cancel out the stab. The lift on the engines or front fuselage is not uniform with increase in angle? There is some spike at a certain angle?

The h. stab trim range is never limiting for stall testing. The airplane can be trimmed at forward and aft CG's at all weights without approaching either nose up or nose down h. stab limits.

See Reply #2518 for comments on the rest of your response.

Interested wrote:

But how many other commercial planes would even test pilot skills in this way?

How many other commercial planes would try and crash themselves?

Any commercial airplane that has a runaway stab trim and the crew does not deal with it correctly.

Interested wrote:

It means it has the potential to crash if you don't deal with it

If this is your definition of "death trap", I suggest that you avoid automobiles with adaptive cruise control.

Otherwise, you may be a sensor failure away from serious harm to your self or others if the situation is not dealt with correctly.

OldAeroGuy wrote:

DenverTed wrote:

OldAeroGuy wrote:

The intent is to
obtain enough data to determine the stall speed at an entry rate not exceeding 1.0 knot/second.

I take it that means a deceleration of less than 1.0 knot/second to stall, during which the control pressure must increase. So the righting force curve went flat or up on the MAX in this zone?

You must obtain enough data to correct the stall speed to an entry rate of 1.0 knot/second. Some stalls will have an entry rate greater than 1.0 knot/sec and some will have less.

The stability level does not have to be flat or go unstable to fail 25.203. Here are some hypothetical cases:

Case 1 - Passes 25.203
AoA - Stick Force - lbs
4 - 0 (trimmed)
5 - 5
6 - 10
7 - 15
8 - 20
9 - 25
10 - 31
11 - 37 (stall warning)
12 - 39 (stall)
A stall of this type would be indicative of stall starting on the inboard wing. The change in stick force gradient after stall warning is acceptable.

Case 2 - Fails 25.203
AoA - Stick Force - lbs
4 - 0 (trimmed)
5 - 5
6 - 10
7 - 15
8 - 20
9 - 25
10 - 28
11 - 30 (stall warning)
12 - 32 (stall)
A stall of this type would be indicative of stall starting on the outboard wing. The configuration is stable throughout the stall as stick force must be increased to stall the airplane. The change in gradient after 9 deg AoA causes the airplane to fail 25.203. This is the type of stall handling is typically called "stick lightening". The 737 MAX probably has this type of stall approach behavior and is why MCAS was added.

Case 3 - Larger H. Stab, Fails 25.203
AoA - Stick Force - lbs
4 - 0 (trimmed)
5 - 6
6 - 12
7 - 18
8 - 24
9 - 30
10 - 33
11 - 36 (stall warning)
12 - 38(stall)
The larger h. stab increases overall stability and stick forces but "stick lightening" due to outboard wing stall is still present and the change in stick force gradient flunks 25.203.

Case 4 - MCAS added, Passes 25.203
AoA - Stick Force - lbs
4 - 0 (trimmed)
5 - 5
6 - 10
7 - 15
8 - 20
9 - 25
10 - 30 (MCAS activates)
11 - 36 (stall warning)
12 - 40 (stall)
A properly implemented MCAS system is not a bad idea. Similar concepts may be imbedded in many FBW airplanes and invisible during normal operation.

My apologies, but is there a specific reference for these interpretations?
Our beloved 25-7 has graphs only for force vs speed, and all your examples would be acceptable if AoA is interpreted as "AoA required at given speed". Gradient as dF/dx doesn't change sign in your examples, and I don't see references for second derivative requirements.

Interested wrote:

I've seen a report a couple of weeks ago suggesting the warning light would have allowed the Ethiopian pilots to recognise and identify their problem earlier

If that's true then it's end of argument about whether or not it would have helped them.

Do you have a source for the suggestion? I'm curious how this conclusion was reached.

As the ET302 crew did not deal with a stall warning (ie stick shaker) shortly after lift off or an "Airspeed Unreliable" Alert correctly, it is hard to understand how having an "AoA Disagree" message would have improved the situation.

OldAeroGuy wrote:

Interested wrote:

But how many other commercial planes would even test pilot skills in this way?

How many other commercial planes would try and crash themselves?

Any commercial airplane that has a runaway stab trim and the crew does not deal with it correctly.

Interested wrote:

It means it has the potential to crash if you don't deal with it

If this is your definition of "death trap", I suggest that you avoid automobiles with adaptive cruise control.

Otherwise, you may be a sensor failure away from serious harm to your self or others if the situation is not dealt with correctly.

There was no run away stab trim, there was an aggressive nose down trim by the flight automatic. How many other current commercial frames go into aggressive nose down trim on the failure of one sensor?

The adaptive cruse control is yet again a dismal comparison. If the cruse control would accelerate on the failure off one sensor, you would have a comparison. On the failure of the cruise control, nothing hinders you to brake yourself. The car is not actively trying to kill you and your passengers.

mjoelnir wrote:

Engineers are responsible for their design. Negligence has put engineers into prison before. Why should aircraft engineers get a special dispensation? Anyway we are not only talking about engineers.

Oh really?
Please cite some examples of engineers going to prison due to negligence.

OldAeroGuy wrote:

Case 2 - Fails 25.203
AoA - Stick Force - lbs
4 - 0 (trimmed)
5 - 5
6 - 10
7 - 15
8 - 20
9 - 25
10 - 28
11 - 30 (stall warning)
12 - 32 (stall)

Thanks for that example. I see the change in gradient between 8 and 11. Although it takes more force, it requires less force per degree of change than previous.

A friend said this morning that they saw a TV news show recently about the whole 737 MAX thing. He got from the show that the 737 has been unairworthy since production started, that Boeing will start scrapping the MAX soon and may have to ground the whole 737 fleet as unairworthy.
I haven't tried to see or read every single thing about this and don't intend to start. I don't even know what show it was? I do not want to start a news source-bashing session either. But, does this sound like anything that was on TV recently? What show?
The best response could be no-response and I'll certainly respect that, too.
Thank

OldAeroGuy wrote:

Interested wrote:

I've seen a report a couple of weeks ago suggesting the warning light would have allowed the Ethiopian pilots to recognise and identify their problem earlier

If that's true then it's end of argument about whether or not it would have helped them.

Do you have a source for the suggestion? I'm curious how this conclusion was reached.

As the ET302 crew did not deal with a stall warning (ie stick shaker) shortly after lift off or an "Airspeed Unreliable" Alert correctly, it is hard to understand how having an "AoA Disagree" message would have improved the situation.

Your opinions are not fact no matter how many times you dress them up as such.


Ray

par13del wrote:

Anyone interested in when the storage of the MAX a/c start affecting the other programs that need the space, in particular the 787?
Thankfully they have another location to produce the 787 that does not have space being taken up by the MAX a/c., can they increase the rate there, are the production locations customer specific?
If the 787 is to continue to provide the cash flow, it has to continue flow smoothly, it does need some storage space of its own.

737s are produced (and parked) in Renton. 787s are produced in Everett and Charleston. 737 storage thus does not affect the ability of 787s to leave the factory.

jomur wrote:

Can happen in the UK amongst other places. Designers also can be jailed for bad designs that cause deaths.. Google is your friend..

Nope.
The person making the claim has the burden of proof. They should not expect others to do the research to for them to prove or disprove what they write.

kalvado wrote:

My apologies, but is there a specific reference for these interpretations?
Our beloved 25-7 has graphs only for force vs speed, and all your examples would be acceptable if AoA is interpreted as "AoA required at given speed". Gradient as dF/dx doesn't change sign in your examples, and I don't see references for second derivative requirements.

It's basic airplane aerodynamics.

AoA is a better fundamental parameter for describing airplane state than speed as speed varies greatly with weight. As a function of CG position and Flap configuration, there is a given Lift Coefficient as a function of AoA.

VKEAS = (Airplane Weight*295.37/(Wing Area *CL))^.5
where
KEAS = knots, equivalent airspeed
CL = Lift coefficient from the Airplane Lift curve as a function of AoA.

For instance, for a 737 MAX type airplane:

Wing Area: 1370 sq ft
CL@ 4 deg AoA (Flaps Up) = 0.65 (an educated guess on my part)
Max Takeoff Weight = 181,200 lb
Empty Weight = 99,360 lb

With these conditions, speed at 4 deg AoA:
Max Takeoff Weight - 245 KEAS
Empty Weight - 182 KEAS

From my example, the associated stall speeds would be:
Max Takeoff Weight - 188 KEAS
Empty Weight - 140 KEAS

The example stick forces are illustrative only and are not based on real data.

MainelyRick wrote:

A friend said this morning that they saw a TV news show recently about the whole 737 MAX thing. He got from the show that the 737 has been unairworthy since production started, that Boeing will start scrapping the MAX soon and may have to ground the whole 737 fleet as unairworthy.
I haven't tried to see or read every single thing about this and don't intend to start. I don't even know what show it was? I do not want to start a news source-bashing session either. But, does this sound like anything that was on TV recently? What show?
The best response could be no-response and I'll certainly respect that, too.
Thank

Rick, the closest I found to your friend’s comment is this purportedly by Ralph Nader.

https://www.commondreams.org/views/2019 ... -or-resign

His grand niece was on the ET flight. I haven’t trusted his opinion since the 2000 election.

XRAYretired wrote:

OldAeroGuy wrote:

Interested wrote:

I've seen a report a couple of weeks ago suggesting the warning light would have allowed the Ethiopian pilots to recognise and identify their problem earlier

If that's true then it's end of argument about whether or not it would have helped them.

Do you have a source for the suggestion? I'm curious how this conclusion was reached.

As the ET302 crew did not deal with a stall warning (ie stick shaker) shortly after lift off or an "Airspeed Unreliable" Alert correctly, it is hard to understand how having an "AoA Disagree" message would have improved the situation.

Your opinions are not fact no matter how many times you dress them up as such.


Ray

We'll both need to wait for the Final Report. Until then, we're all expressing opinions.

mjoelnir wrote:

The adaptive cruse control is yet again a dismal comparison. If the cruse control would accelerate on the failure off one sensor, you would have a comparison. On the failure of the cruise control, nothing hinders you to brake yourself. The car is not actively trying to kill you and your passengers.

The cruise control doesn't have to accelerate based on the sensor failure, just fail to brake.

And you would always have the option to brake, just as the crews could always trim against MCAS.

Remember "Interested" specified that a "death trap" included a failure to apply corrective action.

Interested wrote:
It means it has the potential to crash if you don't deal with it

OldAeroGuy wrote:

Interested wrote:

I've seen a report a couple of weeks ago suggesting the warning light would have allowed the Ethiopian pilots to recognise and identify their problem earlier

If that's true then it's end of argument about whether or not it would have helped them.

Do you have a source for the suggestion? I'm curious how this conclusion was reached.

As the ET302 crew did not deal with a stall warning (ie stick shaker) shortly after lift off or an "Airspeed Unreliable" Alert correctly, it is hard to understand how having an "AoA Disagree" message would have improved the situation.

Surely if the ET crew believed such a warning existed, and it wasn't activated, that would point them in other problem-solving directions?

Lion MX may well have asked the question of earlier flight crews.

OldAeroGuy wrote:

kalvado wrote:

My apologies, but is there a specific reference for these interpretations?
Our beloved 25-7 has graphs only for force vs speed, and all your examples would be acceptable if AoA is interpreted as "AoA required at given speed". Gradient as dF/dx doesn't change sign in your examples, and I don't see references for second derivative requirements.

It's basic airplane aerodynamics.

AoA is a better fundamental parameter for describing airplane state than speed as speed varies greatly with weight. As a function of CG position and Flap configuration, there is a given Lift Coefficient as a function of AoA.

[....]
The example stick forces are illustrative only and are not based on real data.

I understand they are just an example, but lets consider example a bit closer.

OldAeroGuy wrote:

Case 2 - Fails 25.203
AoA - Stick Force - lbs
4 - 0 (trimmed)
5 - 5
6 - 10
7 - 15
8 - 20
9 - 25
10 - 28
11 - 30 (stall warning)
12 - 32 (stall)
A stall of this type would be indicative of stall starting on the outboard wing. The configuration is stable throughout the stall as stick force must be increased to stall the airplane. The change in gradient after 9 deg AoA causes the airplane to fail 25.203. This is the type of stall handling is typically called "stick lightening". The 737 MAX probably has this type of stall approach behavior and is why MCAS was added.

What you're showing in this example is the rate of force decrease, d^2F/da^2.
I am referring to fig. 7.2 in AC 25-7D where "acceptable" curve (vs speed) shows that exact behavior - decrease of derivative to zero at the edge. You interpret such behavior (vs AoA) as unacceptable.
So where does that come from?

kalvado wrote:

OldAeroGuy wrote:

kalvado wrote:

My apologies, but is there a specific reference for these interpretations?
Our beloved 25-7 has graphs only for force vs speed, and all your examples would be acceptable if AoA is interpreted as "AoA required at given speed". Gradient as dF/dx doesn't change sign in your examples, and I don't see references for second derivative requirements.

It's basic airplane aerodynamics.

AoA is a better fundamental parameter for describing airplane state than speed as speed varies greatly with weight. As a function of CG position and Flap configuration, there is a given Lift Coefficient as a function of AoA.

[....]
The example stick forces are illustrative only and are not based on real data.

I understand they are just an example, but lets consider example a bit closer.

OldAeroGuy wrote:

Case 2 - Fails 25.203
AoA - Stick Force - lbs
4 - 0 (trimmed)
5 - 5
6 - 10
7 - 15
8 - 20
9 - 25
10 - 28
11 - 30 (stall warning)
12 - 32 (stall)
A stall of this type would be indicative of stall starting on the outboard wing. The configuration is stable throughout the stall as stick force must be increased to stall the airplane. The change in gradient after 9 deg AoA causes the airplane to fail 25.203. This is the type of stall handling is typically called "stick lightening". The 737 MAX probably has this type of stall approach behavior and is why MCAS was added.

What you're showing in this example is the rate of force decrease, d^2F/da^2.
I am referring to fig. 7.2 in AC 25-7D where "acceptable" curve (vs speed) shows that exact behavior - decrease of derivative to zero at the edge. You interpret such behavior (vs AoA) as unacceptable.
So where does that come from?

So, 10 - 25.01, 11 - 25.02, 12 -25.03 is within spec? Or is there some minimum increase in force? I'm curious about the actual details of the need for MCAS. And the differences in behavior between the NG and the MAX, and the 7 and the 10. I hope this all eventually comes out in some form for inquiring minds and natural curiosity if nothing else.

What's the new range of MCAS? Is it needed when the stab is configured at 5 nose up, or just high configs like 10 nose up? At 5 nose up it should have more righting authority than at 10 nose up in a stall, right?

smartplane wrote:

OldAeroGuy wrote:

Interested wrote:

I've seen a report a couple of weeks ago suggesting the warning light would have allowed the Ethiopian pilots to recognise and identify their problem earlier

If that's true then it's end of argument about whether or not it would have helped them.

Do you have a source for the suggestion? I'm curious how this conclusion was reached.

As the ET302 crew did not deal with a stall warning (ie stick shaker) shortly after lift off or an "Airspeed Unreliable" Alert correctly, it is hard to understand how having an "AoA Disagree" message would have improved the situation.

Surely if the ET crew believed such a warning existed, and it wasn't activated, that would point them in other problem-solving directions?

Lion MX may well have asked the question of earlier flight crews.

Based on the ET preliminary report they correctly diagnosed an MCAS runaway and seem to have intended to perform the runaway stabilizer NNC. They just didn't do it as it was intended but they did move the cutout switches to cutout. To me, this says that they knew they had a runaway trim issue. I don't see how having "AoA Disagree" on the PFD would have changed their actions.

As for the post earlier that said that there were experts or something that said the ET crew might have recognized it sooner if the warning was there, MCAS activated the first time at 05:40:00. The first manual electric counter trim was about 13 seconds later. MCAS activated again at 05:40:21 and manual electric counter trim was engaged at 05:40:28. They seem to have moved the cutoff switches at 05:40:36.

This data says to me that they either recognized the issue was MCAS at 05:40:28 or 05:40:36. If the warning worked, would they have continued the trim command at 05:40:13 to completely trim out MCAS? I don't think so because I don't see a reason to have stopped before balancing the forces without the warning (PW100, if your theory of trim not moving past 2.3 is correct then the warning wouldn't have helped either).

The only way I see that the warning might have led to a different outcome with ET is that since it would have activated prior to flap retraction they may have not retracted the flaps even though that isn't part of a trained procedure on an AoA disagree warning.

DenverTed wrote:

What's the new range of MCAS? Is it needed when the stab is configured at 5 nose up, or just high configs like 10 nose up? At 5 nose up it should have more righting authority than at 10 nose up in a stall, right?

Based on the official Boeing statement, it will be variable. I'm guessing based on pre-activation trim and current airspeed.

MCAS can never command more stabilizer input than can be counteracted by the flight crew pulling back on the column

It doesn't say specifically how much force they need to use on the column. Since it is called out as a feature of the update, one can only assume that it means some normal level of force that doesn't take a super human to exert. Technically, with MCAS 1.0 the crews were able to maintain altitude and even climb with full nose down trim for a while but it probably took ridiculous effort to do so.

morrisond wrote:

Jamie514 wrote:

. . . . .

Actually I did point out all the 737 runway excursions as a problem - probably due to over reliance on auto throttle and not knowing what the plane was doing. I've also said about 500 times that this is worldwide problem not just an ET one.
The attempts in the sim were at the point way after the proper procedure should have been applied as has been discussed many times.

Find me a Sim where they put the plane in trim, had control of the airplane and hit the cut off switches and still crashed.

Apparently, the plane somehow did not allow them [ET crew] to put the plane in trim before hitting the cut off switches

mjoelnir wrote:

morrisond wrote:

DocLightning wrote:

Boeing Commercial does not make money from Boeing Defense. Boeing Corporation does, of course and they could use that money to subsidize BCA. However, that would mean that BCA is not self-sustaining. The 787 program is cashflow-positive and has been since 2016, but the program has still not recouped the initial development costs and is nowhere near doing so. (1) The most optimistic projection is that if Boeing can negotiate prices aggressively and minimize future production costs, they may be able to maintain a 25% margin on each frame, which could zero-out the balance by the end of the program and might even turn a very small (a few million) overall program balance.

The 767 program, while now a defense product, is likely profitable for BCA, as is the 777, although the 777X program is of course running at a net loss because they haven't delivered any frames yet. Fortunately, that program doesn't seem to have run into any major snags yet.

(1)https://seekingalpha.com/article/4190295-boeing-787-going-zero?page=2 (Note: free registration required)

If the Defense side was losing money for some time I'm sure Boeing Commercial would support it. I'm pretty sure when Boeing borrows Corporate Money it is based on the whole companies ability to repay.

From a cash flow standpoint - which is the critical thing while the MAX is grounded - it doesn't matter how much of the 787 Deferred cost is being repaid as that is just an accounting entry which is already paid for in the balance sheet - Boeing owes it to itself.

The 787 Program itself will provide enough actual cash flow (Money received from Airlines on Delivery) over and above cash production cost when frames are delivered to probably put $4-5billion on Boeing's Cash Flow line this year with about 168 Deliveries.

Literally all the MAX grounding does for Cash flow is remove the cash flow Boeing would have used to fund Share repurchases - less the inventory interest costs of not being able to deliver completed frames.

With an $500B backlog - if they don't have enough cash to cover 300-400 undelivered frames - it won't be that difficult to get financing to cover that - assuming the credit lines don't exist already.

The one big caveat - is if the FAA mandates a Frame redesign or something (which I don't think is needed and so far the FAA has said nothing about) which could take a few years - but then Boeing just shuts the program (and moves onto NSA production in 5-6 years probably at a new non-union greenfield site) or reverts to 737NG production at very small profit margins and smaller numbers to keep the workers in place and not lose that infrastructure.

The above is highly unlikely though and we should hear within a month or so what the final solution will be.

Boeing will still be here 12 months from now.

I completely agree with that Boeing will still be there, not only in 12 months, but years from now. But meanwhile there will be tough times ahead.

I do not agree that the deferred cost is just an accounting entry, than cash flow would also be just an accounting entry.

The deferred cost are either profits declared, but not yet made, or losses made but not yet declared. Take your pick.
The deferred cost also influence declared inventories, as they are parked as part of Boeing's inventory.
Additionally to that, Boeing, or better its shareholders, have no equity.

The above is no problem in good times, but can raise its ugly head, when the going gets tough

Right now cash is King - what their reported earnings are are immaterial. I have no idea what the exact numbers are for the 787 - but right now If the actual cost of production is $100 Million (Parts Plus Labour to assemble them) they are selling them (getting cheques from Airlines on Delivery) for some amount a lot higher than that - call it $130-140 Million - meaning if they deliver 14 in a month that's half a Billion they can use for other purposes other than paying for 787 Production.

kalvado wrote:

What you're showing in this example is the rate of force decrease, d^2F/da^2.
I am referring to fig. 7.2 in AC 25-7D where "acceptable" curve (vs speed) shows that exact behavior - decrease of derivative to zero at the edge. You interpret such behavior (vs AoA) as unacceptable.
So where does that come from?

It comes from this:

"8.1.5.3.3 During the approach to the stall, the longitudinal control pull force should
increase continuously as speed is reduced from the trimmed speed to the
onset of stall warning. Below that speed some reduction in longitudinal
control force is acceptable, provided it is not sudden or excessive."

Fig 7.2 addresses an overall airplane speed stability requirement. For small portions of overall speed stability, small slope reversals are acceptable. This is distinct from the stall handling requirements of FAR 25.203 that are quoted above. For stall handling, a reduction in stick force gradient (dV/dF or dAoA/dF) is not acceptable prior to stall warning. As an aside, stall warning is based on AoA, not speed due to stall speed variation with airplane weight.

As a point of reference, AC25-7C was applicable for 737 MAX flight test. AC25-7D was not adopted until 05/04/2018, after 737 MAX certification.

PW100 wrote:

morrisond wrote:

Jamie514 wrote:

. . . . .

Actually I did point out all the 737 runway excursions as a problem - probably due to over reliance on auto throttle and not knowing what the plane was doing. I've also said about 500 times that this is worldwide problem not just an ET one.
The attempts in the sim were at the point way after the proper procedure should have been applied as has been discussed many times.

Find me a Sim where they put the plane in trim, had control of the airplane and hit the cut off switches and still crashed.

Apparently, the plane somehow did not allow them [ET crew] to put the plane in trim before hitting the cut off switches

This is your theory, not a fact. Please don't present it as a fact. Just as you say it would be a coincidence that the trim always stopped at 2.3 units , I can say it would be a hell of a coincidence that they moved the switches exactly at the moment that it reached 2.3 units so that the stabilizer would move linearly right to that moment but it would have stopped abruptly if they didn't move the switches. Nothing in any schematic shows that the thumb switch command can go away with anything but releasing the thumb switch or moving the cutout switches.

PW100 wrote:

morrisond wrote:

Jamie514 wrote:

. . . . .

Actually I did point out all the 737 runway excursions as a problem - probably due to over reliance on auto throttle and not knowing what the plane was doing. I've also said about 500 times that this is worldwide problem not just an ET one.
The attempts in the sim were at the point way after the proper procedure should have been applied as has been discussed many times.

Find me a Sim where they put the plane in trim, had control of the airplane and hit the cut off switches and still crashed.

Apparently, the plane somehow did not allow them [ET crew] to put the plane in trim before hitting the cut off switches

Yes as they left the Thrust levers in TOGA - there was not much they could do until they fixed that.

It reminds me of the 1995 Darwin Award

"The Arizona Highway Patrol were mystified when they came upon a pile of smoldering wreckage embedded in the side of a cliff rising above the road at the apex of a curve. The metal debris resembled the site of an airplane crash, but it turned out to be the vaporized remains of an automobile. The make of the vehicle was unidentifiable at the scene.
The folks in the lab finally figured out what it was, and pieced together the events that led up to its demise.

It seems that a former Air Force sergeant had somehow got hold of a JATO (Jet Assisted Take-Off) unit. JATO units are solid fuel rockets used to give heavy military transport airplanes an extra push for take-off from short airfields.

Dried desert lakebeds are the location of choice for breaking the world ground vehicle speed record. The sergeant took the JATO unit into the Arizona desert and found a long, straight stretch of road. He attached the JATO unit to his car, jumped in, accelerated to a high speed, and fired off the rocket.

The facts, as best as could be determined, are as follows:

The operator was driving a 1967 Chevy Impala. He ignited the JATO unit approximately 3.9 miles from the crash site. This was established by the location of a prominently scorched and melted strip of asphalt. The vehicle quickly reached a speed of between 250 and 300 mph and continued at that speed, under full power, for an additional 20-25 seconds. The soon-to-be pilot experienced G-forces usually reserved for dog-fighting F-14 jocks under full afterburners.

The Chevy remained on the straight highway for approximately 2.6 miles (15-20 seconds) before the driver applied the brakes, completely melting them, blowing the tires, and leaving thick rubber marks on the road surface. The vehicle then became airborne for an additional 1.3 miles, impacted the cliff face at a height of 125 feet, and left a blackened crater 3 feet deep in the rock."

OldAeroGuy wrote:

mjoelnir wrote:

The adaptive cruse control is yet again a dismal comparison. If the cruse control would accelerate on the failure off one sensor, you would have a comparison. On the failure of the cruise control, nothing hinders you to brake yourself. The car is not actively trying to kill you and your passengers.

The cruise control doesn't have to accelerate based on the sensor failure, just fail to brake.

And you would always have the option to brake, just as the crews could always trim against MCAS.

Remember "Interested" specified that a "death trap" included a failure to apply corrective action.

Interested wrote:
It means it has the potential to crash if you don't deal with it

You are really trying. The cruise control is a helpful automation. If it breaks it does nothing. MCAS in failure mode brings you actively into trouble.

You are still riding the unproven fact, that it is was possible to escape the deadly action of MCAS. What is more, there is no warning from the Boeing flight control, that an important feature is going berserk. Even the AoA disagree, pointing to trouble with exactly the sensor that failed, was not working as Boeing did well know.

The cruise control failing sets up a warning light, in many cars a warning sound and you do the normal thing any usually driver is doing, you start braking when you get to near to the car in front of you. The car is not actively trying to kill you. There is no active action apart from your car slowing down, because automatic throttle is gone. It is not even sure that when the sensor goes down, that you are in a situation where you need to brake.

OldAeroGuy wrote:

kalvado wrote:

What you're showing in this example is the rate of force decrease, d^2F/da^2.
I am referring to fig. 7.2 in AC 25-7D where "acceptable" curve (vs speed) shows that exact behavior - decrease of derivative to zero at the edge. You interpret such behavior (vs AoA) as unacceptable.
So where does that come from?

It comes from this:

"8.1.5.3.3 During the approach to the stall, the longitudinal control pull force should
increase continuously as speed is reduced from the trimmed speed to the
onset of stall warning. Below that speed some reduction in longitudinal
control force is acceptable, provided it is not sudden or excessive."

Fig 7.2 addresses an overall airplane speed stability requirement. For small portions of overall speed stability, small slope reversals are acceptable. This is distinct from the stall handling requirements of FAR 25.203 that are quoted above. For stall handling, a reduction in stick force gradient (dV/dF or dAoA/dF) is not acceptable prior to stall warning. As an aside, stall warning is based on AoA, not speed due to stall speed variation with airplane weight.

As a point of reference, AC25-7C was applicable for 737 MAX flight test. AC25-7D was not adopted until 05/04/2018, after 737 MAX certification.

This particular graph is the same in -7C and -7D, so we're good.
I understand what you say, but I fail to see reversal in your numbers. POssibly just a typo?
Again, here is the dataset:

OldAeroGuy wrote:

Case 2 - Fails 25.203
AoA - Stick Force - lbs
4 - 0 (trimmed)
5 - 5
6 - 10
7 - 15
8 - 20
9 - 25
10 - 28
11 - 30 (stall warning)
12 - 32 (stall)
A stall of this type would be indicative of stall starting on the outboard wing. The configuration is stable throughout the stall as stick force must be increased to stall the airplane. The change in gradient after 9 deg AoA causes the airplane to fail 25.203. This is the type of stall handling is typically called "stick lightening". The 737 MAX probably has this type of stall approach behavior and is why MCAS was added.

Force numbers increase across the range of AoA values. What is decreasing, is the slope of change, but not the sign of slope which FAA interprets as acceptable.

Or my eyes are not doing a good job, can you point specific range where you see the problem? 9-10-11-12 is still increase of force situation.

speedking wrote:

planecane wrote:

mjoelnir wrote:

Engineers are responsible for their design. Negligence has put engineers into prison before. Why should aircraft engineers get a special dispensation? Anyway we are not only talking about engineers.

In what country have engineers gone to prison and what did they do? I am an engineer in the USA and I was never warned of possible criminal charges for making a mistake.

This is not an engineering problem. This is a bean counter problem. The MBAs did it.

This is 100% the truth.

The engineers have admitted through for instance the 60 minutes whistleblower that they absolutely understood the impact an MCAS system would have without redundancy and they quite obviously did not hide this fact from the higher-ups, who regardless persisted with the unsafe system to counter the Airbus more reliable model of similar efficiency.

I don't think they should necessarily be jailed for this but Boeing needs to be made to pay extremely heavy financial penalties due to their obvious negligence (because it is, don't let the astroturfing on the internet fool you) to ensure this never happens again.

Even if the pilots failed like Morrisond and Planecrane are obsessed with saying, it does not change the fact that Boeing designed an unsafe system which put the pilots in a position where their lack of actions would crash the plane - something which is beyond unacceptable by modern safety standards, and they need to pay a LARGE fine for it.

It doesn't matter if Boeing held a (which is a very naive and generous view to have) 'belief' their pilots could counter the MCAS it does not change the fact that the system was designed with serious flaws to get around certification regulation which they absolutely did intentionally, if you think they did not and did so without knowing, you should understand that suggests far worse things for B. compared to other options.

There really isn't an argument to be made where training was the main cause of this accident when Boeing specifically sold the MAX line with the motivation that they did not require ANY additional simulator training when adequately trained in the NG - if it was really the case that the training had issues, we'd have seen many more NG crashes but guess what - we haven't!

mzlin wrote:

par13del wrote:

Anyone interested in when the storage of the MAX a/c start affecting the other programs that need the space, in particular the 787?
Thankfully they have another location to produce the 787 that does not have space being taken up by the MAX a/c., can they increase the rate there, are the production locations customer specific?
If the 787 is to continue to provide the cash flow, it has to continue flow smoothly, it does need some storage space of its own.

737s are produced (and parked) in Renton. 787s are produced in Everett and Charleston. 737 storage thus does not affect the ability of 787s to leave the factory.

Renton is already quite full, so is Boeing Field. It was also revealed the other day that 787 test flights and deliveries from PAE will be moved to CHS, essentially once a 787 starts its test flights it will be positioned to CHS to free up space at PAE for more 737MAX storage

http://nyc787.blogspot.com/

planecane wrote:

smartplane wrote:

OldAeroGuy wrote:

Do you have a source for the suggestion? I'm curious how this conclusion was reached.

As the ET302 crew did not deal with a stall warning (ie stick shaker) shortly after lift off or an "Airspeed Unreliable" Alert correctly, it is hard to understand how having an "AoA Disagree" message would have improved the situation.

Surely if the ET crew believed such a warning existed, and it wasn't activated, that would point them in other problem-solving directions?

Lion MX may well have asked the question of earlier flight crews.

Based on the ET preliminary report they correctly diagnosed an MCAS runaway and seem to have intended to perform the runaway stabilizer NNC. They just didn't do it as it was intended but they did move the cutout switches to cutout. To me, this says that they knew they had a runaway trim issue. I don't see how having "AoA Disagree" on the PFD would have changed their actions.

As for the post earlier that said that there were experts or something that said the ET crew might have recognized it sooner if the warning was there, MCAS activated the first time at 05:40:00. The first manual electric counter trim was about 13 seconds later. MCAS activated again at 05:40:21 and manual electric counter trim was engaged at 05:40:28. They seem to have moved the cutoff switches at 05:40:36.

This data says to me that they either recognized the issue was MCAS at 05:40:28 or 05:40:36. If the warning worked, would they have continued the trim command at 05:40:13 to completely trim out MCAS? I don't think so because I don't see a reason to have stopped before balancing the forces without the warning (PW100, if your theory of trim not moving past 2.3 is correct then the warning wouldn't have helped either).

The only way I see that the warning might have led to a different outcome with ET is that since it would have activated prior to flap retraction they may have not retracted the flaps even though that isn't part of a trained procedure on an AoA disagree warning.

Bear in mind that AOA DISAGREE would have been displayed from 05:39:00 at the latest and in presence of single side stick shaker may have helped conclude that stick shaker was erroneous more quickly. With IAS and ALT DISGREE also probably present, the crew may have been alerted to the possibility of the MCAS problem, looking out for it and acting more quickly when it engaged. They may even have elected to CUT-OUT stab trim prior to MCAS engaging at a push.They may have elected to keep flaps extended and pulled back the thrust. (Although may they still have retracted flaps because it was still not communicated as a condition of MCAS activation in the documents).

The point is that they were not given the chance because the display was not available.

Ray

qf789 wrote:

mzlin wrote:

par13del wrote:

Anyone interested in when the storage of the MAX a/c start affecting the other programs that need the space, in particular the 787?
Thankfully they have another location to produce the 787 that does not have space being taken up by the MAX a/c., can they increase the rate there, are the production locations customer specific?
If the 787 is to continue to provide the cash flow, it has to continue flow smoothly, it does need some storage space of its own.

737s are produced (and parked) in Renton. 787s are produced in Everett and Charleston. 737 storage thus does not affect the ability of 787s to leave the factory.

Renton is already quite full, so is Boeing Field. It was also revealed the other day that 787 test flights and deliveries from PAE will be moved to CHS, essentially once a 787 starts its test flights it will be positioned to CHS to free up space at PAE for more 737MAX storage

http://nyc787.blogspot.com/

I would assume Boeing should be able to get repositioning flight permits for MAX - or not really?
Some MAX flights were mentioned in this thread, and I suspect there should be some room in the desert...