US administration blames foreign pilots for 737 Max crashes
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As armchair engineer I do have a question: Why isn't there an MCAS cut-off switch that keeps the electric trim buttons operational?
I think that there is agreement that an MCAS runaway gives pilots very hard problems to solve. Where a good pilot may save the plane (and his skin) on a good day. I don't think we want to keep this system unmodified on the 737MAX. It seems some blame already is passed, but I'm waiting for the investigation reports for my final opinion. (It's a Boeing system engineering issue that this MCAS was fitted on the plane, I wonder what the root causes are.)
I think that there is agreement that an MCAS runaway gives pilots very hard problems to solve. Where a good pilot may save the plane (and his skin) on a good day. I don't think we want to keep this system unmodified on the 737MAX. It seems some blame already is passed, but I'm waiting for the investigation reports for my final opinion. (It's a Boeing system engineering issue that this MCAS was fitted on the plane, I wonder what the root causes are.)
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[QUOTE=Bend alot;10473165]Quote - Sam Graves 15 May 2019.
"In the last decade, in the United States there have been nearly 7 Billion passengers flown on 90 Million flights with ONE fatality."
Atlas Air FLT 3591 - 23 Feb 2019 - 3 Fatal
SWA FLT 1380 - 17 Apr 2018 - 1 Fatal
UPS FLT 1354 - 14 Aug 2013 - 2 Fatal
National Air FLT 102 - 29 Apr 2013 - 7 Fatal
UPS FLT 6 - 3 Sep 2010 - 2 Fatal[/QUOTE
And all of these not large mainstream carriers that you and I would fly on.
Every year there are crashes but most , and in 2017 , all, were military, cargo or others non standard passenger revenue flights. Rarely in first world developed countries does an airliner crash with major fatalities. Exceptions exist. AF447 being a classic example.
Y
"In the last decade, in the United States there have been nearly 7 Billion passengers flown on 90 Million flights with ONE fatality."
Atlas Air FLT 3591 - 23 Feb 2019 - 3 Fatal
SWA FLT 1380 - 17 Apr 2018 - 1 Fatal
UPS FLT 1354 - 14 Aug 2013 - 2 Fatal
National Air FLT 102 - 29 Apr 2013 - 7 Fatal
UPS FLT 6 - 3 Sep 2010 - 2 Fatal[/QUOTE
And all of these not large mainstream carriers that you and I would fly on.
Every year there are crashes but most , and in 2017 , all, were military, cargo or others non standard passenger revenue flights. Rarely in first world developed countries does an airliner crash with major fatalities. Exceptions exist. AF447 being a classic example.
Y
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Actually, we do have some data on it, the FDR traces from the preliminary report, but they are so poorly done that they ofuscate the actual values for the trim position, they even seem to use different scales:
https://reports.aviation-safety.net/...RELIMINARY.pdf
Assuming the accident Lion Air flight reached almost 0 degrees of trim before impacting water, we can deduce that the trim scales start at 0.0 degrees, it seems that on the trace for the accident flight each major division is one unit, and for the previous flight each minor division represents one unit.
This would mean on both flights the takeoff trim was between 6.5 - 7.0 units, and on the accident flight the trim reached close to 0.0 units before impact. Assuming that is correct, it means the previous Lion Air flight experienced MCAS bringing trim down to about 2.0 units after about 2 minutes of fighting it, then they fought it for about 3 more minutes, then they used the cutout switches for the first time.
Also, we can deduce that the aircraft was in trim at about 5.0 units on the previous flight. This means MCAS took them out of trim by a maximum about 3.0 units at the worst point, to 2.0 units, and that the stabilizer was not more than 1.5 units out of trim when they used the cutout switches. The trim position seems to oscillate between 3.5 and 6.5 units for most of their fight with MCAS, if we exclude the spike where it seems MCAS was able to temporarily bring the trim down to around 2.0 units.
With the same assumptions, when they re-enabled the electric trim later, MCAS was able to bring the trim down to about 3.0 units. Then, after they brought the trim electrically to about 3.5 units, they used the cutout switches again to turn electric trim off for the rest of the flight. After that it seems they used the trim wheels to bring the aircraft back in trim from about 3.5 units to about 5.0 units.
In any case, assumptions aside, it's clear that the previous flight didn't reach 0.0 units of trim at any point, this is how the trace from the previous flight looked:
One thing to consider is that MCAS can be much worse than a classical stabilizer runaway caused by stuck or fused thumb switches. With the flaps up, there are limits to how much the main electric trim can bring the nose down. Depending on the 737 model, the limit is around 4.0 units from full nose down trim.
Also Satcom Guru recently tried to find 737 runaway stabilizer incidents in NTSB's database, and he wasn't able to find any:
https://www.satcom.guru/2019/05/737-...incidents.html
So the 737 runaway stabilizer procedure was rarely if ever tested in real incidents. And in any case, an MCAS runaway can be much worse than a classical runaway. With that in mind, Boeing insistence that the existing stabilizer runway procedure is enough to deal with MCAS misbehaving is questionable.
https://reports.aviation-safety.net/...RELIMINARY.pdf
Assuming the accident Lion Air flight reached almost 0 degrees of trim before impacting water, we can deduce that the trim scales start at 0.0 degrees, it seems that on the trace for the accident flight each major division is one unit, and for the previous flight each minor division represents one unit.
This would mean on both flights the takeoff trim was between 6.5 - 7.0 units, and on the accident flight the trim reached close to 0.0 units before impact. Assuming that is correct, it means the previous Lion Air flight experienced MCAS bringing trim down to about 2.0 units after about 2 minutes of fighting it, then they fought it for about 3 more minutes, then they used the cutout switches for the first time.
Also, we can deduce that the aircraft was in trim at about 5.0 units on the previous flight. This means MCAS took them out of trim by a maximum about 3.0 units at the worst point, to 2.0 units, and that the stabilizer was not more than 1.5 units out of trim when they used the cutout switches. The trim position seems to oscillate between 3.5 and 6.5 units for most of their fight with MCAS, if we exclude the spike where it seems MCAS was able to temporarily bring the trim down to around 2.0 units.
With the same assumptions, when they re-enabled the electric trim later, MCAS was able to bring the trim down to about 3.0 units. Then, after they brought the trim electrically to about 3.5 units, they used the cutout switches again to turn electric trim off for the rest of the flight. After that it seems they used the trim wheels to bring the aircraft back in trim from about 3.5 units to about 5.0 units.
In any case, assumptions aside, it's clear that the previous flight didn't reach 0.0 units of trim at any point, this is how the trace from the previous flight looked:
One thing to consider is that MCAS can be much worse than a classical stabilizer runaway caused by stuck or fused thumb switches. With the flaps up, there are limits to how much the main electric trim can bring the nose down. Depending on the 737 model, the limit is around 4.0 units from full nose down trim.
Also Satcom Guru recently tried to find 737 runaway stabilizer incidents in NTSB's database, and he wasn't able to find any:
https://www.satcom.guru/2019/05/737-...incidents.html
So the 737 runaway stabilizer procedure was rarely if ever tested in real incidents. And in any case, an MCAS runaway can be much worse than a classical runaway. With that in mind, Boeing insistence that the existing stabilizer runway procedure is enough to deal with MCAS misbehaving is questionable.
Job done
. MCAS can get worse if it’s was not arrested - true but why would it not be arrested?
y
Last edited by yanrair; 19th May 2019 at 22:09. Reason: Grammar
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Look at it from the point of view of the FAA
First the FAA is going to deny all wrongs so as to preserve their pensions. Which is why they will explain that their certification is only appropriate for US-trained pilots.
Then they will cooperate with Boeing to get the plane flying fairly safely. Because the pressure is huge.
Lastly they will take some measures to fix their process. Probably they will erase the possibility of easy certification of a follow-on type, and respecify startle factor as a risk in itself. At this point they might even move to ask for additional verification of the MAX systems.
Edmund
PS. Apparently in the US lawyer-based culture *any* admission of there being an issue is evidence. So the FAA guys cannot admit any problem existing, notrcan Boeing, and any hearings become empty posturing.
First the FAA is going to deny all wrongs so as to preserve their pensions. Which is why they will explain that their certification is only appropriate for US-trained pilots.
Then they will cooperate with Boeing to get the plane flying fairly safely. Because the pressure is huge.
Lastly they will take some measures to fix their process. Probably they will erase the possibility of easy certification of a follow-on type, and respecify startle factor as a risk in itself. At this point they might even move to ask for additional verification of the MAX systems.
Edmund
PS. Apparently in the US lawyer-based culture *any* admission of there being an issue is evidence. So the FAA guys cannot admit any problem existing, notrcan Boeing, and any hearings become empty posturing.
Nor can Ethiopian authorities. Or Indonesian, Or Russia. Because they are all total home goals in that they are national carriers (or close cousins) , crashing in the capital city and being investigated by that same national authority. Don't expect anything too damning in the official reports of any of those three. Saying that the FAA will lie, and Boeing will lie which seems to be a popular trend on this forum is crass in the extreme. Boeing is a fine planeemaker with a wonderful record. The FAA may have flaws which need correcting but rest assured, that will happen. And in any event, many on this forum believe as I do the Max is perfectly flyable even in the circumstances that happened on these two crashes. And remember that the day before a crash WAS avoided by using the correct technique. Yes, yes, it was a funny guy in the jump seat who somehow knew what to do but doesn't that prove the point? How come he know what to do?
I am not so sure that the same can be said of a lot of other Certification Authorities where the national interest is at the forefront. And it is not confined to developing countries as we know.
Cheers for now.
y
Last edited by yanrair; 20th May 2019 at 13:59. Reason: editorial
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This issue has nothing to do with any nation pilot superiority in piloting an aircraft. This issue is directly related to the manufacturer who in this instance neglects to inform airlines and pilots of a system that is new and contrary to any Boeing aircraft behavior we longtime pilots have ever endured. I a Boeing pilot for over 30 years have always been confident knowing that once I had disconnected the autopilot and auto throttle, the aircraft was mine, and mine alone.
I am sorry to tell you that disconnecting the AP and AT only solve part of the problem. The plane is not yours until you get the stab. back in control.
y
Interesting that at no point during the congressional hearings did anyone ask how come the AoA indication failed on both crashed planes.
I am just an engineer with a PhD, not a pilot, and so for me the origin of a malfunction is significant. Safety doesn't start when someone puts his ass on the seat in the pointy end. And as a computer geek I do suspect that the AoA indicator issue is entirely spurious, a software artefact. In a similar occurrence, QF72, the AoA issues were entirely a software problem.
I suspect this sudden silence on an important topic is because a failed sensor is not a liability issue, while a bug is squarely in Boeing's wheelhouse.
Edmund
I am just an engineer with a PhD, not a pilot, and so for me the origin of a malfunction is significant. Safety doesn't start when someone puts his ass on the seat in the pointy end. And as a computer geek I do suspect that the AoA indicator issue is entirely spurious, a software artefact. In a similar occurrence, QF72, the AoA issues were entirely a software problem.
I suspect this sudden silence on an important topic is because a failed sensor is not a liability issue, while a bug is squarely in Boeing's wheelhouse.
Edmund
fdr (as usual) nails it.
Forget about who you want to blame- that argument has been hashed over 5,000 posts in the original ETA thread.
Instead read 14CFR section 25.255 "Out of trim characteristics."
If you do you will read about the limits that either the electronic or autopilot trim systems can autonomously input to the point where control is taken/given to/or regained by the pilot. The reason for this certification requirement is simple: If your autopilot fails and trims nose down (or up) until the point where it can no longer maintain control over pitch will you be handed an airplane that you can recover when the AP disconnects, or will you be unable to control the AC?? Basically 25.255 insures that the two (traditional) electronic mechanisms that control the horizontal stab are tested to insure that neither one is likely to fail into a box that leaves the AC unrecoverable. It does this by arbitrarily setting a three second cap on manual inputs and the maximum input that the AP can make before it cannot control the aircraft.
Sounds good yes?? 25.255 insures that any system that can exert control over the horizontal stab is identified, specified, tested and certified to insure that it does not put the airplane outside the envelope at any time. Take the system to the maximum input it can make and see if the pilots can recover it. Great!!
Except, well wait a minute. There is this new system, called MCAS, that has the authority to run the trim all the way to the nose down stops. In nine-second bursts, wait five, rinse and repeat. 30 to 40 seconds is all it will take it to run your horizontal stab not only beyond your ability to recover, but to the max ANU position.
Ahhh, don't worry, you don't need to know about that system!! And rumors to the effect that it is reliant on a single data source are, oops, true!! Who knew??
This is the moral failure that Boeing made, and the bog which they are now in.
1. Boeing engineers KNEW what MCAS did.
2. They KNEW that under current certification regulations MCAS would not be permitted to be designed or implemented as they did as it could not comply.
3. They KNEW that MCAS could not pass numerous certification requirements, so they buried its existence from view to pretty much everyone. (The Three Monkeys approach...)
4. They KNEW that they submitted certification documents seeking .6 (IIRC) of trim per activation, but put into service a system with more than FOUR TIMES the control authority than that Certificated.
4. They KNEW that they created a system which had full and autonomous control authority over pitch and relied on a SINGLE data point. (C'mon, why are we even discussing this. that fact alone- that alone should put Boeing in custodial care or receivership...)
And the FAA stood by and cheered them on as profits went through the roof.
The cynic in me thinks two years from now Boeing will once again be flying the friendly skies uninhibited by such scrutiny, but the optimist in me thinks they might have actually done it this time. Allowed a deregulated environment to run so far off the rails that the Government actually steps back in and reasserts control.
We'll see I guess-
dce
Forget about who you want to blame- that argument has been hashed over 5,000 posts in the original ETA thread.
Instead read 14CFR section 25.255 "Out of trim characteristics."
If you do you will read about the limits that either the electronic or autopilot trim systems can autonomously input to the point where control is taken/given to/or regained by the pilot. The reason for this certification requirement is simple: If your autopilot fails and trims nose down (or up) until the point where it can no longer maintain control over pitch will you be handed an airplane that you can recover when the AP disconnects, or will you be unable to control the AC?? Basically 25.255 insures that the two (traditional) electronic mechanisms that control the horizontal stab are tested to insure that neither one is likely to fail into a box that leaves the AC unrecoverable. It does this by arbitrarily setting a three second cap on manual inputs and the maximum input that the AP can make before it cannot control the aircraft.
Sounds good yes?? 25.255 insures that any system that can exert control over the horizontal stab is identified, specified, tested and certified to insure that it does not put the airplane outside the envelope at any time. Take the system to the maximum input it can make and see if the pilots can recover it. Great!!
Except, well wait a minute. There is this new system, called MCAS, that has the authority to run the trim all the way to the nose down stops. In nine-second bursts, wait five, rinse and repeat. 30 to 40 seconds is all it will take it to run your horizontal stab not only beyond your ability to recover, but to the max ANU position.
Ahhh, don't worry, you don't need to know about that system!! And rumors to the effect that it is reliant on a single data source are, oops, true!! Who knew??
This is the moral failure that Boeing made, and the bog which they are now in.
1. Boeing engineers KNEW what MCAS did.
2. They KNEW that under current certification regulations MCAS would not be permitted to be designed or implemented as they did as it could not comply.
3. They KNEW that MCAS could not pass numerous certification requirements, so they buried its existence from view to pretty much everyone. (The Three Monkeys approach...)
4. They KNEW that they submitted certification documents seeking .6 (IIRC) of trim per activation, but put into service a system with more than FOUR TIMES the control authority than that Certificated.
4. They KNEW that they created a system which had full and autonomous control authority over pitch and relied on a SINGLE data point. (C'mon, why are we even discussing this. that fact alone- that alone should put Boeing in custodial care or receivership...)
And the FAA stood by and cheered them on as profits went through the roof.
The cynic in me thinks two years from now Boeing will once again be flying the friendly skies uninhibited by such scrutiny, but the optimist in me thinks they might have actually done it this time. Allowed a deregulated environment to run so far off the rails that the Government actually steps back in and reasserts control.
We'll see I guess-
dce
I won’t deny, though, that minimizing the visibility of the MCAS to the regulators and certainly the pilots may have deliberately occurred to minimize differences training for the MAX and meet contractural obligations.
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If only there was some sort of switch, acted upon by the control column, whereby if a pilot pulled back on the yoke, the switch automatically cut off forward trimming (and vice versa). Pilots wouldn't even have to think about it...it would be instinctive.
Oh, wait! I just checked my MAX FRM. It says there IS such a system! Section 9.2.5.2.1
It goes on to describe the STAB TRIM OVRD switch, to take that column switch out of the loop, in case that it fails. It does NOT mention the fact that the MCAS is wired into that OVRD switch, and defeats the purpose of the column cutout switches. Actually, it doesn't mention MCAS at all...but we already knew that.
Oh, wait! I just checked my MAX FRM. It says there IS such a system! Section 9.2.5.2.1
It goes on to describe the STAB TRIM OVRD switch, to take that column switch out of the loop, in case that it fails. It does NOT mention the fact that the MCAS is wired into that OVRD switch, and defeats the purpose of the column cutout switches. Actually, it doesn't mention MCAS at all...but we already knew that.
As I have said before the runaway could be due to a now dead rodent that chewed an electric cable. The pilot does not have to know _why_ the stab trim is stepping nose down - only that the pilot wants/needs to stop it and to do that follow the Stab Trim runaway NNC as was done by the first Lion Air flight and was published by Boeing along with the AD after the crashed Lion Air flight. Neither crashed aircraft followed the Stab Trim Runaway NNC correctly.
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I would place a large bet that some engineer at Boeing new exactly what SCAM errr... MCAS does and when. In a project like this somebody knows what any one part or fuctionality does. It is just what happens in a design process.
Yanrair -
And remember that the day before a crash WAS avoided by using the correct technique. Yes, yes, it was a funny guy in the jump seat who somehow knew what to do but doesn't that prove the point? How come he know what to do?
I have to say I'm getting a little tired of this kind of superficial blather from people who, according to their claims of experience, ought to know better. It's a bit ridiculously obvious that the third pilot didn't have to busy himself with the other things going on in the cockpit, and could place the trimwheels in the center of his vision and focus on them for long enough to see what they were doing. The other two pilots could not do so, just like the accident crews.
To pretend to ignore those facts is to reveal a preference for point-scoring over honest debate, just like the continued posturing about how hypothetical "western" pilots would have coped with the problem easily.
And remember that the day before a crash WAS avoided by using the correct technique. Yes, yes, it was a funny guy in the jump seat who somehow knew what to do but doesn't that prove the point? How come he know what to do?
I have to say I'm getting a little tired of this kind of superficial blather from people who, according to their claims of experience, ought to know better. It's a bit ridiculously obvious that the third pilot didn't have to busy himself with the other things going on in the cockpit, and could place the trimwheels in the center of his vision and focus on them for long enough to see what they were doing. The other two pilots could not do so, just like the accident crews.
To pretend to ignore those facts is to reveal a preference for point-scoring over honest debate, just like the continued posturing about how hypothetical "western" pilots would have coped with the problem easily.
Sorry, while I am critical of Boeing’s design decisions and the regulatory system, I do not accept that we KNOW the Boeing engineers were fully aware of all the non-normal characteristics of the MCAS, nor that regulators deliberately overlooked them. I hope the various investigations do uncover how all this went wrong, and correctly identify the systematic flaws in the delegation system that minimizes substantial technical oversight by the FAA.
I won’t deny, though, that minimizing the visibility of the MCAS to the regulators and certainly the pilots may have deliberately occurred to minimize differences training for the MAX and meet contractural obligations.
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That video is typical of the amateurish analysis that pervades the debate around these two accidents. If you really want to know if a different crew could have saved the aircraft you would start from the initial state existing when the malfunction occured, as opposed to this scenario where they began from the point the cutout was selected.
You cannot replicate the startle effect with a warned crew.
What would be of interest is, get a measure of the time window a crew actually has before throwing the cutout switches and still be able to recover.
I'd say if it is less than one minute, this is a very short time indeed, even for a first class crew on a good day.
Last edited by Fly Aiprt; 21st May 2019 at 16:09. Reason: Typo
[QUOTE=GlobalNav;10475730]
Sorry, while I am critical of Boeing’s design decisions and the regulatory system, I do not accept that we KNOW the Boeing engineers were fully aware of all the non-normal characteristics of the MCAS,
Well, they bloody well should have been!
Sorry, while I am critical of Boeing’s design decisions and the regulatory system, I do not accept that we KNOW the Boeing engineers were fully aware of all the non-normal characteristics of the MCAS,
Well, they bloody well should have been!
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Possibly even less than 38 seconds as there is a 5 seconds uncertainty on the cutout switch activation time.
It is quite short.
And if the crew is not aware that there is a missing line in the trim runaway NNC
- "Put back the airplane in trim using the electric trim buttons before flipping the cutout switches",
and if the crew had only trained this NNC in a simulator where the manual trim forces are lighter than what they are in reality,
and if the crew is quite exhausted fighting an Elevator Feel System that creates ANU opposing forces 4 times the normal forces,
why wouldn't they have flipped the switches as soon as possible ?
In my armchair and after receiving much more information than the crew had at hand, I can see that there existed better options than what the crew chose to do.
But why is there here so many pilots convinced that they would have done better ?
IMHO, the point where the crew could have taken the time to discuss and think twice at their options is after flipping the cutout switches.
The time when they had a stable and controllable airplane, albeit with difficulties.
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Hi there Edmund
Nor can Ethiopian authorities. Or Indonesian, Or Russia. Because they are all total home goals in that they are national carriers (or close cousins) , crashing in the capital city and being investigated by that same national authority. Don't expect anything too damning in the official reports of any of those three. Saying that the FAA will lie, and Boeing will lie which seems to be a popular trend on this forum is crass in the extreme. Boeing is a fine planeemaker with a wonderful record. The FAA may have flaws which need correcting but rest assured, that will happen. And in any event, many on this forum believe as I do the Max is perfectly flyable even in the circumstances that happened on these two crashes. And remember that the day before a crash WAS avoided by using the correct technique. Yes, yes, it was a funny guy in the jump seat who somehow knew what to do but doesn't that prove the point? How come he know what to do?
I am not so sure that the same can be said of a lot of other Certification Authorities where the national interest is at the forefront. And it is not confined to developing countries as we know.
Cheers for now.
y
Nor can Ethiopian authorities. Or Indonesian, Or Russia. Because they are all total home goals in that they are national carriers (or close cousins) , crashing in the capital city and being investigated by that same national authority. Don't expect anything too damning in the official reports of any of those three. Saying that the FAA will lie, and Boeing will lie which seems to be a popular trend on this forum is crass in the extreme. Boeing is a fine planeemaker with a wonderful record. The FAA may have flaws which need correcting but rest assured, that will happen. And in any event, many on this forum believe as I do the Max is perfectly flyable even in the circumstances that happened on these two crashes. And remember that the day before a crash WAS avoided by using the correct technique. Yes, yes, it was a funny guy in the jump seat who somehow knew what to do but doesn't that prove the point? How come he know what to do?
I am not so sure that the same can be said of a lot of other Certification Authorities where the national interest is at the forefront. And it is not confined to developing countries as we know.
Cheers for now.
y
Actually in the case of AF 447, AFAIK, the french investigatory authorities made a bunch of recommendations, which included meteorologic research, AoA display, mods to training and CRM, data transmission and flight recorders. One question which the report clearly posed is whether the actions of the crew were confined to that crew or would have been expected of any crew.
You can read the AF 447 final report at this link, the interesting stuff in my view starts around page 190.
[url]https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp090601.en.pdf
Note that here too there is a specific recommendation involving the fact that AoA display should be mandatory. (page 205).
4.2.2 Recommendation relating to Certification
Angle of Attack Measurement
The crew never formally identified the stall situation. Information on angle of attack is not directly accessible to pilots. The angle of attack in cruise is close to the stall warning trigger angle of attack in a law other than normal law. Under these conditions, manual handling can bring the aeroplane to high angles of attack such as those encountered during the event. It is essential in order to ensure flight safety to reduce the angle of attack when a stall is imminent. Only a direct readout of the angle of attack could enable crews to rapidly identify the aerodynamic situation of the aeroplane and take the actions that may be required.
Angle of Attack Measurement
The crew never formally identified the stall situation. Information on angle of attack is not directly accessible to pilots. The angle of attack in cruise is close to the stall warning trigger angle of attack in a law other than normal law. Under these conditions, manual handling can bring the aeroplane to high angles of attack such as those encountered during the event. It is essential in order to ensure flight safety to reduce the angle of attack when a stall is imminent. Only a direct readout of the angle of attack could enable crews to rapidly identify the aerodynamic situation of the aeroplane and take the actions that may be required.
€ that EASA and the FAA evaluate the relevance of requiring the presence of an angle of attack indicator directly accessible to pilots on board aeroplanes.
My view after reading both the AF447 report and viewing the congressional hearings in the US is that the rot ie. regulatory capture is more serious in the US, although the french are by no means perfect, they did make an effort. Of course, there is the fact that calling all AF pilots *exceptionally *stupid won't work in France. When you have an accident, you want to tell your customers that you are going to do anything you can to avoid it, including changing the certification requirements and training curriculum. Telling your customers that they are idiots doesn't usually make them happy, Calling them foreign idiots as the congressional inquiry is doing is much worse..
Edmund
Last edited by edmundronald; 21st May 2019 at 16:17.
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I am still wondering why there are two cutout switches, renaming them from previous versions, removing the possibility of cutoff of automatics...
From a system design, i would question any engineer that feels the need to have two cutout (a primary and a back up) when the whole systems is based on a single input and a single actuator. The CB is already a back up of a failing cutout switch. The understanding of the reasons why such idiotic cut out system was designed is the basis to fully understand how the whole system was though... or NOT