Aviation regulator outlines fixes that will get the 737 MAX flying again The United States' Federal Aviation Administration (FAA) has revealed the conditions under which it will permit Boeing's beleaguered 737 MAX to resume commercial flights. The 737 MAX was grounded after two crashes in 2018 and 2019 revealed that the plane had shipped with largely undocumented automation features called the " …
A mix of the two. There is low appetite for the classic corporate road warriors to hit the road (the plane) to travel for business now that it's kind of proven that you can do conference calls with Zoom as effectively as spending 6 hours on planes, trains, and automobiles to do the same thing. Aviation analysts Atmosphere Research Group say that now is actually the perfect time to fly because airlines will be disinfecting the planes to yazoo, those who can avoid flying do just that, and you are likely to have a much nicer experience. That's debatable though.
As for the aviation professionals, some look at the recertification (and return to flight) of the MAX as being a good thing because, as others have succinctly pointed out in other MAX-related threads on here, it'll have had its innards deeply inspected, others are planning to avoid the MAX where they can for ideological reasons (Boeing management's horrific response primarily).
It's good to see that the FAA is happy that the 737 Max will soon be fit to fly. However a few thoughts occurred to me.
1) Will other aviation regulators such as the CAA trust the work done by Boeing and the FAA?
2) Will there be any demand for these aircraft, given the slump in flights due to the corona virus pandemic?
3) Will the airlines give the paying customer the choice of risking a flight in an aircraft with such a tainted reputation?
My answers are:
1) Maybe, if the FAA and Boeing are completely transparent on the steps being taken to put right all the faults and design choices that led to the crashes.
2) Probably not in the short term. Airlines have a big enough job trying to coax passengers back given the impositions of mandatory quarantine on a lot of tourist destinations.
3) Not a chance in hell. Firstly, it would definitely put people off, me included, if they were told that they were going to be flying on such a problem riddled design and secondly the logistics of actually informing people would be difficult and probably impossible.
So, to sum up it looks like we are going to have to trust that this time Boeing has got it right and that the FAA has actually done its job and made sure that this aircraft really is safe to fly.
We shall see but I for one will not be volunteering to act as a crash test dummy for the foreseeable future.
"Will other aviation regulators such as the CAA trust the work done by Boeing and the FAA?"
Good question. Europe and China are among those who have said they will not trust the FAA and will make their own evaluations.
Europe has been negotiating with Boeing and the FAA to get this far, so changes they demand are already incorporated. If acceptance leaks into 2021 the UK will no longer be under the European umbrella, but would the CAA want to snub the FAA? They are probably hoping for early certification so they don't have to think about it.
But I'm guessing China is likely to play a joker against America's Trump card (see what I did there? ;-) ) in trade negotiations and refuse.
Whom the rest of the industrialised world chooses to follow will be the interesting bit. A flight where you are licensed to take off or land, but not the other, is not going to go well.
Hmm. Yes but no but yes - I was oversimplifying. The shite list effectively covers Airlines whose use a country specific regulator who is deemed not up to scratch. So both the Airline and the Regulator have to be trusted. I believe there are numerous instances of airlines that certify under other countries regulators for specifically this reason.
"But I'm guessing China is likely to play a joker against America's Trump card (see what I did there? ;-) ) in trade negotiations and refuse."
It wouldn't surprise me, in the current climate between the USA and China, especially if it worsens any further, if China licenced a single 737MAX to fly to China where it can then undergo their own flight worthiness exam "in person".
3) Notification Is a piece of piss technically. The aircraft operating a schedule is a standard piece of information already circulated with all operator and support systems.
You correctly identify the main problem that is if people realise they are flying a MAX they will want to change flights, so therefore the Operator has a built in reason not to tell them.
Sure, only a few passengers will bother checking their actual flight. But there is just going to be endless publicity, month after month, year after year, as to “which airlines are flying the dangerous plane”. Airlines just won’t be able to stay in business with that label around their neck.
And why would they try? Not only could they buy Airbus, at perfectly competitive prices, but there is now the largest glut in history of secondhand planes in storage with barely delivery mileage on them. Why wouldn’t one just pick up a handful of those for cents on the dollar?
To be fair, Ryanair have a lot of MAXs already, and will continue using them.
Their big advertising selling point is “ we are so horrifically crap we must be really cheap”. To the point that nobody notices that they aren’t even that cheap. But there’s really only room for one airline with that shtick.
Just point out to fellow travelers they're about to board a 737 MAX if they hadn't noticed yet and see how many will actually get on board.
Does 'panic attack' count as a medical reason to make use of travel insurance?
I for one will definitely check which airlines are flying 737 MAXes and avoid these airlines like the plague.
I don't understand this line of reasoning. Every pilot in the world will now know that MCAS can cause pitch down when the AoA sensors pack up (which is now less likely as it uses two), it will only execute a single nose down input in such case, and the pilots will know how to disable it after that single event. The hole has been thoroughly plugged. In fact it was probably plugged as soon as the two accident reports achieved widespread circulation. The planes crashed because the pilots got confused and overloaded. If they had known what was happening, they would have executed runaway trim procedure and been fine. Perhaps they could even have left it on and fought it all the way to an emergency landing in reasonable safety, I bet if you put pilots in a simulator and give them a heads up that every x seconds the plane will nose down, they will be able to compensate and hold average altitude, and probably MCAS disables in landing conditions anyway.
So in my opinion there is no reason to avoid the 737MAX in particular. Either you say Boeing stinks and you boycott all their planes because who knows what other mistakes they made, or you now trust this model as much as any other airplane you don't know jack about (or you trust it more because of the scrutiny it is undergoing).
The reasoning is that Boeing has clearly shown that they put profits over safety.
The major people who should have been fired are still at the helm (CFO should have been ousted, along with (at least) the head of engineering), which means that any other product leaving the Boeing factories is a bunch of parts that pass the minimum (theoretical) requirements.
Hell, there was an article a few months ago that Boeing was going to drastically reduce physical stress testing in favour of computer simulated stress testing.
If Boing ever want me to fly in one of their (new) aircraft again, they should start by using C-level management on their test flights, as that's the only way I can be sure they will not skimp on safety and shave another dollar off on production costs.
>"The planes crashed because the pilots got confused and overloaded.
As I understand it the system kept re-enabling itself and the pilots have to use so much force on the "stick" to correct flight that they assume it is stuck and go back to repeat the disabling procedure or conclude it is a different problem. The simulators they practice this on do not reproduce the force needed so even well trained pilots can get confused.
Boeing is in on this too - the only way of telling the difference is from the serial number on the manufacturer's plate on the aircraft - because the type was kept the same to dodge the CAA recertification. So you won't know until you're actually boarding, and look in the door jamb at the plate.
In that case you will avoid the airplane that has had the most intense safety scrutiny and awareness amongst pilots. There won't be a single one who is not fully aware of MCAS and its dangers.
Avoiding all Boeing planes might make more sense on the assumption that these failures stem from systematic corporate culture and governance failures.
Avoiding all planes relying of FAA certification even more so given that they are ultimately responsible for allowing much of this to happen.
It somehow restricts your options though.
Here are some hints:
1) EASA and other certification authorities are part of the FAA's technical group who are evaluating everything Boeing has submitted. They're also part of the group that will provide input to say whether what Boeing has done is enough to convince the FAA that the plane is safe to fly. It's been a collaborative process.
2) Boeing expects to see their orders start to roll through for precisely that reason... older, more inefficient planes will see themselves turfed out to pasture much faster in order to take advantage of better fuel efficiency from the new planes. See British Airways and Qantas retiring their 747s, Qantas, Air France and Singapore Airlines re-evaluating their A380s and parking them in Victorville and Spain for storage (or possibly retirement). Once traffic picks back up, the A380 will return, but the 747 is toast. Delta is dumping their 767s and 777-200s in favour of newer jets. Someone like Southwest will absolutely be bringing in their MAXes to dump their older -500, -600 and -700s.
3) Yes and no. Some airlines (*ahem* Ryanair) have already renamed the jet in their data, so people aren't likely to cotton on that it's a newfangled MAX200 they're on, other airlines are more honest and intend to offer their customers alternatives, and intend to provide reassurance about the plane.
I personally am considering what happens when BA starts introducing the MAX (they've retired their A318 that flies to the US from London City) and they start phasing out their older A319/320/321s they inherited from BMI. Vueling and Iberia are likely to follow given that it's the common parent company (IAG) that made that commitment to Boeing.
Governance changes have already been made. Mostly cosmetic, but some real safety authority has been transferred back to the engineers, from the beancounters who originally stole it. Time will tell whether enough has been done.
The US judicial system is, thank goodness, a law unto itself, despite President Hasn't-the-Brains-of-a-Muppet's best efforts. Nobody does well in trying to second-guess its prognostications, and nothing is likely to happen soon.
The men I have met who wear lipstick do so in order to look like ladies. The ones who want to look like pigs just put on >Don't say it*< uniforms.
* Just a stereotype for the sake of a joke, lads, most of you do a great job - even if you are a bit too apt to offensively stereotype your, ah, clients for "just a joke".
An expensive condition not mentioned, presumably because Vultures cannot imagine anybody unable to fly, is pilot re-training.
Many airlines bought the Max on the strict condition that no expensive and timewasting pilot retraining would be necessary, it was one of the Max's big selling points.
Boeing's own internal recommendation, certain to be endorsed by the FAA, is for proper simulator-based retraining to be introduced. A lot of airlines will then demand compensation for being sold a product under false pretences, in some cases written into the purchase contract. I wouldn't mind betting that some will use it as a loophole for cancelling a purchase they can no longer afford.
I'm not sure this will now be as much of a problem. Anyone who wants to cancel their contract already had that opportunity. But the alternative is still the A320 Neo, which means re-training all your mechanics and possibly re-doing your whole logistics system. Which is worse.
I'm sure it'll be used to screw more financial sweeties out of Boeing. But remmeber that the airlines aren't running close to full capacity, so training pilots isn't the stretch that it would have been even 9 months ago. So I'm sure if Boeing pay up for things like simulator time, it'll be only a bit financially painful for them to sort. I presume it's more of a problem if you're running a mixed fleet of old 737s and new MAXes - but then with MCAS de-fanged like this will it have to be a new type certfification, or just some mandatory training?
That still seems the big question to me. If MCAS can be safely made so much less powerful now, how come Boeing felt they had to beef it up so much in the original test flying program? Because they've still go to fix the problem of the plane climbing due to the aerofoil effects of the bigger engines.
> That still seems the big question to me. If MCAS can be safely made so much less powerful now, how come Boeing felt they had to beef it up so much in the original test flying program? Because they've still go to fix the problem of the plane climbing due to the aerofoil effects of the bigger engines.
I read that the original design, and safety assessments, were based on an "open loop" design, where MCAS would make a single correction, but that it was implemented as "closed loop", so the system would continually poll the AOA sensor and apply further corrections every few seconds. In an "open loop" system with a failed sensor, the annoyance of a single unexpected downward trim is easily correctable. So the failure was probably classed as "minor", and a single sensor input was allowed. In a "closed loop" system, the plane will continually over-rule the pilots until it hits the ground. Clearly in "catastrophic" territory, as demonstrated by Lion and Ethiopian.
Classifying it as one in the safety assessment, but then erroneously implementing it as the other, is what should land people in jail for several hundred counts of manslaughter (never going to happen though - there was good profit to be made, after all). It's also a text-book example of why self-certification is a corrupt disaster. The true American way.
On the positive side for Boeing, fixing it is as "simple" as implementing it the way it was originally designed. Plus a few other tweaks to improve it, since even the way it was originally designed was a bit crappy, and everyone is now looking (only using one sensor, when two were available).
None of that answers the original question though - implementing it with incremental corrections instead of a single action was not due to some misreading of the spec; it was a deliberate change because the original implementation wasn't effective enough reducing flight characteristics back to that of the original plane's. This suggests going back to the original open loop implementation won't be able to do that either.
So it's still a valid question - did they find an alternative way to make it authoritative enough to make the plane behave like another (and if so, how will THAT guarantee not to crash more planes), or did they just give up all pretence of "it's the same plane" and implicitly agreed to incur re-certification of all involved pilots...?
"due to the aerofoil effects of the bigger engine"
The engines had to be moved forward to leave some ground clearance or they would have had to redesign landing gears and such in a very old design, anyway the thrust was moved forward adding to the nose up force especially during take off.
Bigger engines means fatter engines here.
Such a sorry saga.
I am inclined to think that type approval and recertification is what should have been persued by the FAA but they are undoubtedly under pressure from Boeing, the US government and presumably the larger Boeing shareholders, to go for the cheapest option that sounds as though they are doing their job.
Time will tell if they went far enough, assuming the max is going to rise phoenix like into the air again, it will be flying without me that's for sure.
From the article: "Changes to horizontal stabilizer trim wire routing installations are also required, to give pilots better control."
yeah, no, not so much. Unless you count not losing electrical systems as "giving pilots better control"
From the FAA's preliminary report on the return to flight of the 737 MAX:
"6.6 Electrical Wiring Interconnection System (EWIS)
Requirements(§ 25.1707)As part of the FAA’s review of these design changes, the agency re-reviewed the entirety of the 737 MAX horizontal stabilizer control system. This review revealed that the physical separation of the horizontal stabilizer trim arm wiring and the horizontal stabilizer trim control wiring does not meet the criteria specified in 14 CFR 25.1707. This design standard was promulgated in 2007 and therefore is part of the certification basis of the 737 MAX but not of previous Boeing Model 737 airplanes. Certain wiring installations must have enough physical separation so that a wiring failure cannot create a hazard. (See 14 CFR 25.1707)."
"The stabilizer trim arm wiring has since been rerouted in 12 areas of the airplane’s Electrical Equipment bay and Section 48 to prevent a potential simultaneous short circuit between the stabilizer arm and control wiring and another 28VDC wire. "
So much better than the old version of this rhyme.
Exploding centre fuel-tanks, runaway rudders, runaway stabilisers, then crap FMCs, no stall protection and all the other crap they build would keep happening, but the know-nots would still trot out: "If it ain't Boeing, I ain't going".
Glad to not hear that rubbish any more.
Whereas Airbus would never allow fully certified pilots to fly a completely airworthy aircraft into the sea, killing all on board. Air travel is (thanks to a lot of hard work by many able people) an incredibly safe mode of transport, but to claim that one manufacturer is far 'safer' than another is total moonshine.
Pilots can always decide to crash their aircraft.
Air France screwed up their training, not Airbus.
A pilot who thinks "take-off go-around" is a sane mindset at cruising altitude should never have been put in control of an aircraft.
Let alone one who can't even follow the core "decide who is flying this thing" protocol.
The saddest part of that crash is that the aircraft would have been absolutely fine if the pilots had left well alone :(
Ummm, partially. Airbus did agree that the pitot tubes freezing was part of the problem. The suppliers fixed it and everyone retrofitted heated pitot tubes to their Airbus jets. At least airspeed is no longer a disagree case (still happens, but at least less chance of it happening to *all three* tubes at the same time).
Para 3 of the article reads:
"Those errors cost 346 lives and saw Boeing pay at least $19bn in compensation to families of the deceased, payments to airline customers and lost revenue."
How does the $19bn break down between the three items in that list? From memory if you took out the first item, compensation to the families of the victims, the sum lost to Boeing would be... $19bn. The compensation payments were a rounding error on that sum. I'd also suggest changing the paragraph since Boeing haven't paid the overwhelming majority of the sum, they've lost it from the drop in revenue. The paragraph as written implies they have paid it out, when they never had it in the first place.
Corrections by those with a more accurate breakdown of the $19bn welcome.
Have Boeing given up maintaining that they are "making an already safe plane even safer?"
That was a proper tone-deaf new-speak bit of lawyer approved verbiage if ever I've seen one. I haven't yet seen them actually step up and accept any responsibility, presumably because they're still hoping to keep slipping the right envelopes to the right officials and avoid any legal responsibility (remember Trump's comments about needing Einstein to fly planes... whatever that was meant to mean?)
Boeing are "great" at spin. Remember the great 787 Dreamliner battery clusterfuck? They came out with an awesome statement that their batteries hadn't caught fire, they had merely "vented with flame"!
Now I'd have accepted that, if they'd taken up a suggestion that was made here in the El Reg forums. Which was that you put all the batteries down the side of the aircraft, in fireproof boxes, and each has its own bent chromed exhaust pipe poking out the side of the plane, so it looks like a drag-racer. Then it would look super-cool with all the batteries spitting flames out the side, and you'd want them to fail more often.
As for the compensation for passengers thing, isn't it limited by the Warsaw convention still? I know that airlines only have to pay out a maximum of £20 for lost luggage, because in 1920 £20 was a serious amount of money, but it was never index-linked in the treaty. And I thought that also seriously limited liability for killing passengers. Though all bets may be off for Boeing, as if this isn't an example of negligence - then I can't imagine what would be. And that's assuming they're not guilty of worse...
the family of course. People don't get paid just because they are mouth breathers. They get compensated based on the economic worth of that particular person and expected lifetime earnings which is peanuts compared to even 1st world working poor. There's some extra ladled on top for 'pain and suffering' but at the end of the day, if you're from Etheopia and Indonesia your life amounts to very little. Sure, there are the odd doctor and oil or mining exec who brings in big coin so their lifetime earnings are not a rounding error.
Life is short and brutish in most places in the world. What's a life worth in China, in Cambodia, Burma, India, most of Africa or pretty much any Muslim state? Damn close to zero. That's just the facts.
99% of pax have not the foggiest idea of what type of aircraft they're flying in and no interest in finding out. My brother (another techie of the type to be found commenting here, with an engineering degree, so quite interested in mechanical things) once told me he'd flown back on a 747. I didn't think they used them on that route, and checking on FlightRadar found it was a 777 - the only possible clue to the difference being the number of decks and the number of engines :).
In all the years of 737 Max flights two crashed, and they are making fixes now that are going to be required to be above and beyond what they need to do to mitigate the causes of those crashes.
I won't have any problem flying in a 737 Max when it starts flying again. Not that I or 99% of the flying public looks at what type of aircraft is being used before buying a ticket - and airlines are free to change to a different aircraft due to maintenance or even a whim so to those who are afraid - if you walk up to the gate and see that it is a 737 Max are you going to demand to be on a later flight and sit around in the airport or hours or possibly overnight when this occurs?
I think you'll find it's always been an option to have more than one AoA sensor. Two wasn't a requirement for certification, which allowed beancounters to select a cheaper variant with only one. I bet nobody asked the pilots.
I make it that you are an irrational optimist and a bit of a pedant. I imagine the minimum wage call centre email answering drone looked at your email and thought a) what's MCAS? b) why is this person asking me this and c) why does anyone care?
For every 1 El Reg reader who will 'never fly on a 737-MAX' there will be a million customers who don't care, don't know what plane they are on and won't realise that the 737-Nimbus 2000 is a 737-MAX with a piece of vinyl stuck over 'Max'.
Even if they do get a service pack to convert them from rocks into planes, how would we as customers ever know if the particular one we are expected to get onto has been fixed or not ?
How about a big sticker on the way in that we can all see or better still, visibility of the sensors on the plane as we approach ?
I guess the new game is American Roulette, its like Russian Roulette, except they use planes instead of guns.
Personal view - no trust in Boeing as profits came before safety, you can probably bet someone is looking at the big hole in the bottom line and trying to figure out how to fix that for "shareholder value", but I bet nobody is worrying too much about the end customers or learning the real lesson of doing things right, rather than doing things cheap.
Now we know that one sensor can screw the plane, will they be fitting 3 or 5 to ensure that even if one fails, the plane still does what its supposed to - gets people safely from A to B with no nasty surprises.
My next concern - what about all the other places on the plane that the same logic was applied to save a few quid ??
"Even if they do get a service pack to convert them from rocks into planes, how would we as customers ever know if the particular one we are expected to get onto has been fixed or not ?"
If the relevant and competent regulatory body for your area has allowed it to carry passengers for money, it has the fix. Well, if the local FAA equivalent allows it without the fix, they are already probably ignoring much worse.
The AoA sensor is effectively a horizontal weather-vane that rotates to indicate the direction of the air flow. The problem is that it is prone to becoming iced-up and stuck in one position, so failures are not uncommon. While comparing the outputs of two separate sensors is an improvement, it is not that unlikely that both sensors could suffer icing at the same time and get stuck in the same, erroneous position. So it's not as big an improvement as it may first appear to be.
...if only there had been a dog in the cockpit to bite the software when it interfered with the controls...
I assume these fixes also mean that the pilots will no longer have to bust a gut to move the controls when there are significant aerodynamic forces acting on the control surfaces (i.e. at speed).
A long time ago my dad asked for a visit to the cockpit of a 747-300. I met the Pilot, Co-pilot... and the Flight Engineer. Woo!
Air travel was already a stomach churning, back breaking, mind bending experience. Add wearing a mask and\or a face shield for 12+ hours, and we have a recipe for mental breakdown. Top it off with buggy software managing a mismatch between airframe and engine size et al? Thanks, I'll pass, to put it politely.
The MCAS system is bad enough without exaggeration:
"MCAS could not be overridden despite receiving erroneous data from an Angle Of Attack (AOA) sensor".
The MCAS could be overridden but the pilots weren't familiar enough with it to know how. A combination of the system being very difficult to deal with and the pilots not being appropriately trained.
The MCAS could be overridden but the pilots weren't familiar enough with it to know how.
Erm, pulling a specific (tiny) circuit breaker out of dozens and also disabling the electric trim system in the process? Yeah, that's exactly what I want to be doing while hauling back on the yoke trying to keep the suicidal aircraft from killing me.
"A combination of the system being very difficult to deal with and the pilots not being appropriately trained."
Or having magical knowledge that wasn't in the manual, and wasn't mentioned by Boeing so as to make sure that pilots didn't need recertification. But sure, blame the pilots for not knowing about a system that deliberately wasn't mentioned to save Boeing some money and hassle.
I remember reading that the 737 MAX is just generally less stable than its competitors because the engines are so far forward that they're ahead of the center of gravity of the plane. So, if the nose starts going up, the air catching the engine cowling pushes the nose even further up. That's why there's an MCAS in the first place -- to prevent that instability.
Myself, I think I'm going to do my best to avoid flying in these things. It sounds like their fundamental stability depends upon the correct operation of the MCAS software, and the pilot's correct interaction with that software, unlike nearly any other commercial plane flying today. No thanks.
"I remember reading that the 737 MAX is just generally less stable than its competitors because the engines are so far forward that they're ahead of the center of gravity of the plane. So, if the nose starts going up, the air catching the engine cowling pushes the nose even further up. That's why there's an MCAS in the first place -- to prevent that instability."
EXACTLY....The MCAS was put there to prevent the problem caused by using more effcient engines which (IIRC) are larger and hence there was far less clearance between the underside of the engines and the ground. So, they moved the engines and the C of G changed...
And it seems that today (18th Nov) the FAA has cleared the 737 MAX to fly again BUT only after mods have been carried out...but no mention of changing the engines or it's mounting position:
https://www.bbc.co.uk/news/business-54981658
Wouldn’t you like to... Die in my bug riddled airplane?*
We can crash along with automatic systems that did us in...
Oh we can die, we can die..
There’s ZERO chance anyone we know and our family will EVER be on one. Unsafe at any altitude!
(*With respect to the original singers)
the chinese already ripped off the Boeing/Airbus designs for their in-country service aircraft that they are building. So any and all MAX orders are likely long since cancelled by Central Committee dictat and 'investments' already made to compensate those who had orders active.
"If the company meets that deadline, the plane may find eager customers as it looks likely the aviation industry will have low passenger demand for the next couple of years. The 737 MAX offers low running costs and can handle missions ranging from short commuter hops to transatlantic treks, making it capable of replacing some wide-body alternatives."
The way this is phrased makes it appear that it would be the only kid on the block in that market, which is not the case. The whole reason that Boeing took these irresponsible shortcuts to get a 737 MAX in the air was because Airbus launched the A320neo series in 2010 or so That was so much more fuel efficient than anything that Boeing produced at the time that even American Airlines decided to break with its habit of only buying Boeing and ordered a whole lot of Airbus planes instead, and they were far from the only Boeing customers who went "European" instead - hence the panic at Boeing which set off this whole chain of events which ended with two planes physically drawing the curve of Boeing's shares later, and a lot of dead people.
The only eagerness on the side of buyers might originate in an expectation that they will sell the planes at a massive discount to let money overcome the hesitation of airlines to buy something that their passengers may avoid unless the flight is cheap. I can see Ryanair haggle them to death, and maybe Easyjet, but anything non-budget may stick with planes that have proven to (now) stay in the air (let's not forget that Airbus had its own problems) and which passengers will have less reservations about - and that's not mentioning the fact that Boeing will probably need to secure independent approval as the FAA has lost its credibility in the process as well.
Boeing faces a serious uphill climb. Even the smallest problem will give their shares anew the MCAS v1 treatment..
Software changes and additional sensors are all very well, but there is still one fundamental safety item missing - a physical switch to isolate MCAS from input to the motors controlling elevator trim. This simple and effective device would have saved many lives had it been in place from the start, but it would have meant pilot training, so was skipped.
I think it is still necessary to have this as an additional safety feature as the software and sensors may well be working fine, but a physical problem due to heat/fatigue/whatever may cause a continuous nose down output from MCAS. Unlikely but not impossible, so stick in a simple and cheap, easy to test and maintain on/off switch.
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