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  #81  
Old 26.03.2019, 14:22
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

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https://www.seattletimes.com/busines...kpit-displays/

Hamilton [chief engineer of Boeing Commercial Airplanes] defended the optional nature of those features by insisting that “all primary flight information required to safely and efficiently operate the 737 MAX is included on the baseline primary flight display."

That is, the baseline, non-optional displays are all that are needed for safe operation of the MAX.

“There are no pilot actions or procedures during flight which require knowledge of angle of attack,” Hamilton added.
I've just read that article concerning the optional indicator features. Surely some form of indication that MCAS (the previously undisclosed software control system independent from the autopilot) was forcing the plane's nose down into a dive would have been much more useful to help the pilots decide what action to take in such an emergency and should have been a primary feature. Optional lights etc. to indicate discrepancies between sensors etc. are only a secondary measure. The problem is that Boeing wanted to surreptitiously slip MCAS in to attempt to solve another design problem, this time with the integration of the larger engines, so could not provide such a useful warning feature without exposing the new MCAS system to unwanted and time consuming certification scrutiny.
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  #82  
Old 26.03.2019, 14:48
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

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“There are no pilot actions or procedures during flight which require knowledge of angle of attack,” Hamilton added.
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A final note: The AOA (angle of attack) wasn't displayed to the crew in the cockpit, only the pitch angle was. Newer aircraft now display both. I think it was a recommendation of the BEA after AF447 accident, were the crew couldn't figure out the AOA they were at after a Pitot-static froze.
https://aviation.stackexchange.com/q...-of-an-airfoil
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  #83  
Old 26.03.2019, 16:47
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

From Tuesday's WSJ:

https://www.wsj.com/articles/ethiopi...ax-11553518027


From Seattle Times (front page/above the fold):

https://www.seattletimes.com/busines...ation-process/

"But it’s unclear if these changes and the MCAS software fix, even if certified, will be enough to lift the grounding of the Boeing jets."

If they are never allowed to fly again, how about buying up all the fuselages dirt cheap and starting a worldwide chain of some 400 airport restaurants (or even bars) appropriately called "Max's Place?"


From Reuters:

https://www.msn.com/en-us/money/comp...dG2I?li=AA5a2s

Last edited by AlaskaGuy; 26.03.2019 at 17:06.
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  #84  
Old 26.03.2019, 19:16
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

From https://www.msn.com/en-us/news/us/us...cid=spartanntp

"Boeing has said it is making changes to its software on the Max. The company announced it would now make standard an indicator light that warns pilots of a sensor malfunction that could cause its anti-stall system to activate unnecessarily.

"Investigators believe that anti-stall system, new on the 737 Max, triggered on Lion Air flight 610, repeatedly forcing down the nose of the plane, leading to last October’s crash into the Java Sea.

"The previously optional indicator light was not installed on the Lion Air plane that crashed, or on Ethiopian Airlines flight 302, which went down under similar circumstances on March 10.

"A U.S. airline source said that feature would cost roughly $80,000 extra on a plane with a list price of about $120 million."

Eighty grand for a light? With glass cockpits, it wouldn't actually be a physical light. It would be a rectangular block of pixels on a display (most likely the PFD) illuminated based on a single-bit value in a customer- or airplane-specific configuration table.

Even if it were a physical light, it still wouldn't likely cost much more than 80 dollars of "machinist" labor to install on the assembly line. That would be a thousand-fold markup! I put "machinist" in quotes since these workers are basically assemblers -- they couldn't operate a lathe or milling machine if their lives depended on it.
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  #85  
Old 26.03.2019, 21:40
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

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...The company announced it would now make standard an indicator light that warns pilots of a sensor malfunction that could cause its anti-stall system to activate unnecessarily...
Why not install redundancy with the indicator itself, rather than a stupid warning light that tells you it is malfunctioning? Boeing is really dropping the ball on this, methinks.
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Old 26.03.2019, 21:41
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

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Eighty grand for a light? With glass cockpits, it wouldn't actually be a physical light. . . .
I thought that as well, but it is apparent that these systems are not well integrated.

The display concept appear to be designed to show pictorial representations of the old style analog instruments (like animations out of a video game) to make the transition for pilots of earlier generation models easier.
The design philosophy seems to have been that when a new system component comes along e.g MCAS, rather than spend resources to integrate it into the existing platform, simply find a free place somewhere to glue on an indicator light (if the customer is willing to pay extra for it, that is) and maybe find also place somewhere to mount a switch to disable it.

I could imagine, if it was done properly, the MCAS system would have been fully integrated with, and subordinate to, the auto pilot (rather than fighting with it) so switching off autopilot would have brought the aircraft under more complete manual control. Anyway, clear messages would have appeared on the console saying exactly what was going on (sinking nose X degree due to stall risk based on input from from angle of attack sensor Y or whatever), maybe including page references to the flight control manual for a fuller description and maybe some hints and tips as to how to prevent a crash.

The cost of all this is going to dwarf the projected $80k per plane, and it is not impossible to imagine that foreign approval authorities will not simply accept the Boeing/FAA's assessment that the talked about software patch and a few technical lash ups is enough to allow the MAX series to fly again in their airspaces.
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  #87  
Old 27.03.2019, 00:45
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

Not well integrated" seems a gross understatement.

Pre-"glass" 737s had a pair of "six-pack" annunciator panels (one each for pilot & co-pilot) as described here:

http://www.flaps2approach.com/journa...alled-and.html

for the airplane to tell the crew what ails it.

When glass came along, EICAS (Engine Indication and Crew Alerting System) gave brief textual messages to the crew on a display on the center console.

As you say, logically, MCAS should have been an enhancement to the auto-pilot, but that would have entailed large cost to "open up" that logic -- which may well be analog -- and re-certify it. When I worked at Boeing when the 777 had only been in service for a few years, I heard that Honeywell charged us $10K per additional EICAS message plus a $megabuck to recertify it after putting the cover back on. So we thought up the kludgiest ways to avoid new EICAS messages by, say, triggering two existing unrelated messages simultaneously, expecting the crew to remember (or look it up while things were going badly) to deduce what the airplane was really saying. We still had to pay the megabuck, so going to such nonsense to save a few $10K seems goofy.

As far as MCAS pushing the nose down using trim, that's exactly what we tell primary students NOT to do, PARTICULARLY to stop an approaching stall. You briskly push the yoke forward to recover airspeed. Trim is NOT for controlling the airplane -- it's for relieving the forces you're currently applying to the controls so the airplane flies "hands off." I don't understand (and nobody seems to be asking) why MCAS isn't another input to the "stick pusher" (as opposed to "stick shaker" to warn of impending stall) which I'm sure the 737 must have to push the nose down -- once -- when stall is detected, say, by low airspeed. For the pilot to have to crank the elevator trim wheel (even if using the up/down trim switches on the control yoke, which I think MCAS disables) to undo what MCAS did seems ludicrous -- just position the yoke (fore vs. aft) back to a middle-ish position after recovering airspeed and then recovering the altitude you lost.

MCAS sounds to me like the Mother of All Kludges -- as does the whole notion of putting oversized engines forward of and above the wing so they don't inhale grass clippings to avoid having to modify the wing.

For the longer MAX 10, here's yet another kludge to avoid having to make the gear wells larger to accommodate taller gear to avoid tail strikes on rotation:

https://www.flightglobal.com/news/ar...design-451546/

Boeing proudly calls this the "Innovative Shrink Link!"

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  #88  
Old 27.03.2019, 09:27
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

One German consultant speculates that it could have been caused by what he calls blowback, a phenomenon that would have left the crew only a very short time to react. The MCAS would be the underlying cause but the fall itself would be caused by an additional effect.

See here.
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Old 27.03.2019, 10:04
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

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One German consultant speculates that it could have been caused by what he calls blowback, a phenomenon that would have left the crew only a very short time to react. The MCAS would be the underlying cause but the fall itself would be caused by an additional effect.

See here.
So if I read the article correctly it suggests that because of the MCAS trimming the nose down the plane got to fly too fast at low altitude - to the point where the elevators were not able to pull the plane out of the resulting dive? That's pretty nasty situation to get in. Stupid question: would pulling back the throttle / airbrakes / flaps have been a way to slow down and regain control in that situation?
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Old 27.03.2019, 10:53
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

https://interestingengineering.com/p...t-malfunctions

Part of that effort was ensuring that the 737 MAX 8 received the same aircraft rating as previous 737 aircraft. That way, pilots who had already been certified to fly those earlier 737 models could have their existing certification extend to the 737 MAX 8 as well. There would be no need for airlines to spend money on training since, as Boeing would sell it, the pilots already knew how to fly the new plane.

The problem is that the as part of the new automated system, the MCAS, the anti-stall function was entirely new to the 737 MAX 8 aircraft, a consequence of a modification to the placement of the engine on the wing that changed the aerodynamics of the plane, but improved efficiency. Pilots qualified to fly the earlier 737 models would have had no experience with this system. Designed to engage only if a pilot took so steep an angle that the plane would stall, it was considered simply an automatic failsafe, something a pilot would rarely, if ever, encounter. Boeing and regulators believed that pilots didn't even need to be told about this feature at all, and only sent out notices about the system after the Lion Air investigation started to suggest that this system might have played a role in the crash.

According to some reports by pilots, the extent of their training on the new 737 MAX 8 aircraft was a one hour online course using an iPad, with zero training done in an actual simulator. What's more, according to at least one anonymous pilot complaint submitted to the Aviation Safety Reporting System, the new anti-stall feature was also not fully explained in some flight manuals even after the notices went out after the Lion Air crash, prompting the pilot who filed the report to call the documentation of the MCAS anti-stall feature "inadequate and almost criminally insufficient".

In order to fully shut down the MCAS function that was pushing the plane into a nosedive, the pilots would have to flip the switch at their thumb, then flip two more switches elsewhere that would shut down the power to the motor the MCAS used to push the nose down. Then, the pilot would then need to turn a crank to fix any remaining problems caused by the system before they would have control of the aircraft again.

Three different switches in a specific order followed turning a wheel with a crank—while fighting an autopilot system seemingly hellbent on sending the plane into a nosedive—in less than 40 seconds. In the simulation, knowing the procedure in advance and knowing that the MCAS system was going to be triggered so they would be primed to carry out the maneuver, the pilots were able to successfully shut the system down and land the plane safely.
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  #91  
Old 27.03.2019, 11:11
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

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So if I read the article correctly it suggests that because of the MCAS trimming the nose down the plane got to fly too fast at low altitude - to the point where the elevators were not able to pull the plane out of the resulting dive? That's pretty nasty situation to get in. Stupid question: would pulling back the throttle / airbrakes / flaps have been a way to slow down and regain control in that situation?
It would be enough to reduce/remove the trim tab setting (which, according to the "elevator blowback", was eventually, with increasing speed and resulting pressure, becoming higher than what the actuator driving the elevator surface could deliver).
Wikipedia reference-link Trim_tab
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Old 27.03.2019, 13:39
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

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. . .
For the longer MAX 10, here's yet another kludge to avoid having to make the gear wells larger to accommodate taller gear to avoid tail strikes on rotation:

https://www.flightglobal.com/news/ar...design-451546/

Boeing proudly calls this the "Innovative Shrink Link!"
That should provide Boeing marketing with another valuable up-selling opportunity. This time an expensive light to fix somewhere in the cockpit, to indicate if one or both landing gear extensions fails to operate, thus warning the pilot that the aircraft may tend, on landing, to turn in a tight circle with one of the engine cowls scraping noisily along the ground.
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  #93  
Old 27.03.2019, 19:06
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

From today/Wednesday's Seattle Times:

https://www.seattletimes.com/busines...ed-on-the-jet/

Rick Ludtke, a former Boeing engineer who worked on designing the interfaces on the MAX’s flight deck, said managers mandated that any differences from the previous 737 had to be small enough that they wouldn’t trigger the need for pilots to undergo new simulator training.

That left the team working on an old architecture and layers of different design philosophies that had piled on over the years, all to serve an international pilot community that was increasingly expecting automation.

“It’s become such a kludge, that we started to speculate and wonder whether it was safe to do the MAX,” Ludtke said.
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Old 28.03.2019, 15:07
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

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Boeing and regulators believed that pilots didn't even need to be told about this feature at all
I think this is a hugely inappropriate behavior, regardless of the impact of the specific feature or the probability of it being encountered. Even if the feature wasn't an automatic system that could take control of the plane - which it is! - no pilot should ever be kept from knowing what the machine could do. If I were a pilot I would be totally enraged.
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Old 28.03.2019, 15:22
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

I read an article yesterday. Apparently the manual for the 737 Max is over 1,500 pages long and only mentions MCAS once - as an entry in the glossary to spell out the acronym.

There's no mention of what the system is or what it does, much less how to disable it.

https://www.cbc.ca/news/business/boe...rash-1.5065842
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Old 28.03.2019, 16:07
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

@ Phil_MCR "Boeing and regulators believed that pilots didn't even need to be told about this feature at all".

One wonders how many other features are "hidden"!
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  #97  
Old 28.03.2019, 16:39
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

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@ Phil_MCR "Boeing and regulators believed that pilots didn't even need to be told about this feature at all".
. . .
FTFY: "Boeing and regulators believed that pilots and regulators didn't even need to be told about this feature at all"

Interesting is also, that in explaining why the US was so late in grounding these aircraft, the FAA has inverted the burden of proof in matters of safety by implying that an aircraft is considered safe to fly unless it is 100% certain that it should be grounded. Conventional wisdom would dictate that unless it is 100% certain that the aircraft is safe to fly, it should remain grounded.
https://www.wsj.com/video/acting-faa...E2B845B1E.html
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Old 28.03.2019, 18:14
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

The BS (aka Boeing Stink) just keeps coming.


From today/Thursday's WSJ:

https://www.wsj.com/articles/how-boe...ed-11553699239

Throughout the MAX’s development, Boeing was intent on minimizing design changes that could require extra pilot training, said Rick Ludtke, a former Boeing engineer who worked on 737 MAX cockpit features but not the MCAS system. Extra training could have added costs for airlines introducing the MAX into service.

The company had promised Southwest Airlines Co. , the plane’s biggest customer, to keep pilot training to a minimum so the new jet could seamlessly slot into the carrier’s fleet of older 737s, according to regulators and industry officials.

Mr. Ludtke recalled midlevel managers telling subordinates that Boeing had committed to pay the airline $1 million per plane if its design ended up requiring pilots to spend additional simulator time. “We had never, ever seen commitments like that before,” he said.

-and-

Bryan Lesko, an airline pilot who wrote an article last year for his union’s magazine about the 737 MAX before it entered service, repeatedly asked Boeing officials if there were any major new systems. The answer was no, according to a person who recently discussed the matter with him.


Also from today's WSJ:

https://www.wsj.com/articles/dot-sec...s&page=1&pos=1

… acting FAA Administrator Daniel Elwell told a separate Senate panel that there had been no flight tests of the 737 MAX to gauge how pilots would react in the event that a malfunctioning sensor triggered an automated stabilizer program known as MCAS.

Last edited by AlaskaGuy; 28.03.2019 at 18:45.
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Old 29.03.2019, 14:39
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

The BS just keeps coming:

From Reuters today:

https://www.msn.com/en-us/news/world...cid=spartanntp

FAA's Transport Airplane Directorate, which oversees design approvals and modifications, was concerned about whether the 737 MAX system complied with regulations because the thumb switches could not control trim on their own in all conditions.

FAA declined to comment on the European document. A trim-related "equivalent level of safety" (ELOS) memorandum listed in its 737 MAX certification document is not available on the FAA website. The agency declined to provide it to Reuters.

and

On the 737 MAX, Boeing removed the "yoke jerk" function that enabled pilots to disable the automated trim system with a hard pull on the control column rather than hitting two cut-out switches on the center console.

In a blog post on his personal website, former Boeing engineer Peter Lemme said that could make things harder for a pilot in a crisis.

"In the scenario where the stabilizer is running away nose down, the pilot may only fixate on pulling the column back in response," he said. "They may not be mentally capable to trim back or cutout the trim - instead they just keep pulling."


Today/Friday's Seattle Times (front page/below the fold):

https://www.seattletimes.com/busines...stic-and-slow/


FWIW, the total number killed on the two MAXs together, 346, is exactly the same as the number killed in 1974 when the baggage door blew out on a Turkish Airlines DC-10 just outside Paris. This remains the deadliest single-aircraft accident without survivors.

Last edited by AlaskaGuy; 29.03.2019 at 15:53.
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Old 29.03.2019, 21:00
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Re: Ethiopian Airlines ET 302 crashed near Addis Ababa

I guess now that MCAS has been outed, Boeing's most hopeful strategy is admitting that it was the cause of the 2 fatal crashes, announcing a load of technical fixes, documentation updates and revised training recommendations etc., and hope that the planes will soon be accepted once again as airworthy.

However, if the Max design and certification procedure was so sloppy, one big question raised (also here) is what other compromises could have they made which present a safety risk and can the situation be potentially so bad that a complete review of the design and certification is required ? This, to a certain extent, will also depend on the attitude of global certifying bodies other than the FAA.

Clear is, this affair has highlighted the problems between the business side and the technical side of the industry.
The marketing side negotiate the deals, set the prices and the technical side has to work within rules defined by the cost constraints.
The solutions which have emerged have probably fulfilled the cost requirements but the safety (or regulatory) aspects has not been given due weight.
It has also highlighted the role of regulators in ensuring (or failing to ensure) a healthy balance between safety and costs and demonstrated failure to police best practices (no single point of failure, proper peer review of technical solutions, etc. etc.) and allowing tricks to be played to get the technical designs implemented and all the paperwork and rubber stamps in all the right places.

Well, if there is to be a thorough review to discover if there are more "hidden" design issues, one solution would be to introduce an anonymous reporting or "whistle blowing" system (analogous the Venetian Bocca di leone denunciation box) where engineers could deposit reports highlighting problem areas. (At the moment, they appear to have been using the Seattle Times for this purpose.) So, just as an example, an electrical engineer who specified the connection of the new ovens for the inflight meals to the cockpit emergency lighting circuit could report this with the explanation that his boss wouldn't allow, on costs grounds, another cable to drawn from the generator. This could flush out a few of the risks.

As far as getting the planes back in the air, one wild card in this is China. China was the first to ground the Max. Notwithstanding all the issues relating to a trade negotiations with the US, there is the point that China has its own aircraft development in the "Max" market segment (Comac C919) and will potentially have a huge internal market. China will calculate that the efforts of the US through regulatory and other pressures on Huawei, ZTI etc. to damage their market competitiveness in the communications industry could be mirrored in the aircraft industry via US agencies including the FAA. This is not only a theoretical risk. The Anglo-French supersonic Concode project, a triumph of aviation technology, is one example where the US successfully sabotaged the commercial success of a highly innovative airline development, in an area where it had no competing product, by the calculated revision of noise regulations restricting its use to all but a few airports with the objective of ensuring that the project could not be viable. It will be interesting to see if China now uses this affair to makes a strike against role of the FAA or enhance the role of its own air safety governing body.

In the meantime, Boeing sales will no doubt be busy working on a new name for the Max series.
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