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chrisg

Problems with the 737MAX ?

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I'm never inclined to leap to judgement over aircraft accidents but the early evidence of the similarities between LionAir and Ethiopian are rather stark.

 

The AAIs will obviously look at the evidence from an unbiased standpoint and Boeing will doubtless start squealing that the pilots should have known of the potential issue from their NOTAMs but other possible causes are longer reaches given the evidence to date.

 

Air accidents are always tragic when lives are lost but there are some nasty similarities not only between these two crashes but also another period of Boeing's history. There were a spate of crashes of the 727 in its early days. The common denominator was found to be primarily a lack of understanding of the deep stall characteristics of rear-engined jets which were new to the aviation industry particularly with an aircraft the size of the 727.

 

Boeing resolved the issue with additional warning systems, an improved stick shaker/pusher system and training but not before several aircraft had crashed.

 

Even that did not stop the Papa India Trident crash when the pilot repeatedly disabled the very systems telling him he had a deep stall condition caused by neglecting to extend the leading edge slats for take-off. Pilot error of course but the airliner industry moved away from rear engine designs despite several, including the 727 and Trident,  going on to have long mostly accident-free service lives. I once spoke to a BAC-111 co-pilot who saved his aircraft when the captain had given up in a deep stall on a training flight, the possibility remained but pilot awareness improved and the likelihood of further incidents pretty much vanished.

 

I've no problem with rear-engined jets at all, flown more than enough of the smaller varieties, but the deep stall condition is nowhere near as marked in shorter bodied aircraft.

 

I don't think I'll be getting on a 737Max until the report is in.

 

Cheers

 

 

 

 

 

 

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I mean it could be pilot error but the guy had 8000 hours of flight time, and Ethiopian Airlines have a young fleet and a decent safety record with only one prior crash (there was another, due to terrorism in the mid 90s)...

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The  first thing everyone tends to look at is pilot error but an 8,000 hour pilot flying out of what must be a familiar airport to him is unlikely to do something that would lead to oscillating flight and a near vertical crash dive as is being reported.

 

That leaves a mechanical error which the new addition of the stall over-ride could be thought of. Most other mechanical errors apart from a complete breakup, which the evidence does not support, or another radical control failure would be about all that could cause that. The pilot did call the airport to ask to RTB so something mechanical other than the suspected issue with Lionair also seems unlikely.

 

A possible bird strike has been mentioned, some big birds, vultures, around there but a 737 could handle that.

 

I've flown in and out of the old airport in Addis, the new one this flight was operating from came after my times in Africa but it's a pretty benign area to fly in with no dangerous  terrain to speak of and the weather was reported to be ok. It is high, bit over 7,000 feet if I recall but African pilots get used to operating from high fields. Addis is not alone, both Johannesburg and Nairobi are high locations, and others.

 

Time will tell but if any of the safety authorities get suspicious then they could well ground the MAX fleet until the frankly rather afterthought of a stall reaction system is properly sorted - the damned thing doesn't even have proper sensor redundancy. It could be implied that Boeing have made light of how to cope with the system failure, I hope not, that is bad for business and bad for image quite apart from killing people.

 

Boeing are somewhat new to FBW systems on airliners compared to their arch-rival Airbus. It is frightening but possible that that relative inexperience with such systems on commercial aircraft, the company has plenty of military FBW experience but that is in different divisions of a vast organisation, may be a factor.

 

Cheers

 

 

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Posted (edited)

Is it possible the anti stall-system in the Max8s were mishandled by the pilots, say going back a old habits for different aircraft?

Edited by Jeruselem

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Not really J.

 

The MCAS is automatic and it is somewhat confusing as to just when it is armed.

 

Different articles give different opinions, so much so I have a request in for an extract of the manual that was updated after the LionAir crash.

 

Some reports say it is only on when on autopilot, others say it can cut in during manual flight if an approaching stall is detected. Once invoked it can be disabled via a button on the yolk but apparently it has to be kept pressed to remain deactivated - that doesn't seem right but it is what is being reported. It does seem from reports post LionAir that it is best disabled by pulling a breaker which is down low to the co-pilot's side of the cockpit wall.

 

Easier said than done when the aircraft is pitching down and it is resisting pilot inputs to pull up whilst the "nagging nellie" terrain avoidance is shrilling "pull up. pull up".

 

So much is being poorly reported by people who don't know what they are talking about,  but it does seem clear that the system can exert a lot of push down force that the crew can reverse but then it pushes again - that would not be nice.

 

The reality is that if the system were working properly it should hardly ever cut in in the first place, airliners are not supposed to stall, upsets the passengers, and the pilots.

 

For this to happen, if it is the cause of two crashes, something is wrong in the FBW code or the sensors are prone to false inputs. Inevitably there is an analogue to digital interface which is where I'd be looking first, in a simulator.

 

Cheers

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Yes, sometimes I wonder if I should be early for flights...

 

This MCAS conundrum is getting a lot of criticism from pilots especially as it is a system by the same acronym but rather different in its operation that exists on the 737NG and does not seem to cause any problems.

 

The implication, supported by some comments apparently made by Boeing, is that the system on the MAX was made light of so as not to confuse pilots... A system of the same name but different methodology on a different aircraft would seem to me to be more confusing if you have not been made aware of the changes.

 

Boeing made a big deal about the MAX being so similar to fly to earlier 737s that training could be minimal to transition - a big selling point for airlines but from my quick read of the specifications and the scant mention of the MCAS in the MAX manual does not seem to be borne out.

 

The MAX is a larger aircraft with new engines, a change in CofG and increased FBW systems. Those are hardly trivial changes but the Boeing stance was they could use software to make the aircraft feel the same.  Airbus has been taking that route for most of its fleet of offerings but according to Airbus pilots they have done a much better job.

 

We'll see, eyewitness reports of the aircraft being on fire etc BEFORE it crashed probably don't have much credence, eyewitnesses are typically unreliable but the AAIs will have to look at that regardless.

 

Not having ever flown a 737 at all, although have spent a number of hours in various cockpits I'm on a learning curve but everything I've read thus far says the MAX is a very different beast.

 

Cheers

 

 

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Yeah, closing the stable door but it really begs a question:

 

If the code re-write or whatever is projected to take six months, quite apart from that being rather a long period even in aviation with exhaustive testing regimes mandatory why did Boeing not simply issue a directive to MAX operators, backed by the FAA, to disable MCAS until the code update was released ?

 

In normal flight MCAS is hardly ever needed and pilots do know how to react to a stall without needing a computer to do it for them. They also understand trim adjustments perfectly well, the very system itself seems almost superfluous and to be frank an emergency waiting to happen if it malfunctions.

 

The 737 is not, or in the case of the MAX should not be a relaxed stability airframe but MCAS has the appearance of being partly with that intent. Such systems are almost unique to military aircraft, to allow greater maneuverability plus various other virtues, such as stealth but it is rarely seen on commercial designs. An exception, Wiki tells us, which I did not know, heavies are not my thing, is/was the MD11, essentially the DC-10 after ownership change. It was employed on that less than stellar aircraft to improve fuel efficiency but seems to have caused problems in any event.  (On a side note one of the most pleasant commercial flights I have ever had was on a DC-10, lovely aircraft but obviously somewhat flawed.)

 

On the 737MAX it would seem to me MCAS is "nice to have" if it works as intended but not essential and is suspected to be capable of disastrous flight interference.

 

Boeing may well have stretched the 737 form factor one step too far if they have had to resort to artificial input even if their claim is it was to give a common feel to the aircraft.

 

My feeling is I'd be happy to fly on a MAX with MCAS disabled, would not until shown otherwise contemplate flying on one with MCAS in the loop.

 

I don't know, although have asked, but there must have been some considerable training requirements over 50 years as new models of the 737 rolled out, not least the move to glass cockpit.

 

So have over 300 people died to save a few training dollars and make it easier to sell a new aircraft ?

 

Or is it deeper than that, did Boeing push the envelope too far to have the MAX compete with the  Airbus 320 Neo ?

 

Commercial aviation is a very cutthroat business in many ways, that suspicion is entirely within the bounds of possibility.

 

If it is the case Boeing are going to need to do a lot more than just re-write some code, and quickly, or the big order book for the MAX will collapse.

 

Cheers

 

 

 

 

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Australia has joined the growing number of countries temporarily banning 737MAX operations in their airspace.

 

https://www.news.com.au/travel/travel-updates/incidents/virgin-pilot-body-says-it-has-utmost-confidence-in-boeing-max-8/news-story/2680f4379969f1a73b5351f51f17c0e6

 

Virgin can afford making statements of confidence, their aircraft are probably not even in production yet and supporting Boeing is always good for a discount...

 

If one U.S. airline grounds its MAX' s  Boeing's share price is going to need a pull up to avoid a nose dive.

 

Cheers

 

 

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Posted (edited)

The UK and by the look of it most of the EU has banned MAX flights, they even turned back a couple of Turkish flights denying them landing in most all of Europe.

 

It's probably a matter of time before United, who fly the MAX-9, Southwest and AA follow suit and ground their flights - quite possibly unnecessary, the U.S. pilots seem to have it sorted out but the cold truth is the public don't want to fly on a MAX.

 

Cheers

 

 

Edited by chrisg

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https://www.abc.net.au/news/2019-03-13/737-max-pilots-reported-two-control-issues-in-2018-to-nasa/10895542

Key points:

  • Two pilots separately reported to NASA that they suspected automated controls in their Boeing 737 MAX planes were faulty
  • Both planes suddenly tilted mid-flight but were quickly corrected
  • North American carriers have continued to fly the 737 MAX, despite groundings elsewhere

 

 

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Hmm,

 

It would be damned nice if, as a pilot SOMEONE would clarify just when MCAS is in the loop. Boeing most certainly do not in the manual extract that I've seen and that is who should make the system clear.

 

Frankly it does not really make sense, and goes to the now emerged pilot reports J linked for MCAS to be engaged when autopilot is on but off in manual control when the stated procedure to disengage the thing when having a fight with the yoke is to pull up and having to keep it out of the loop by repeatedly holding, not adjusting, trim.

 

The incident reports linked and what is known about the two crashes seems contradictory.

 

I'd suspect from the evidence that MCAS is ever present but obeying different laws depending on auto on or off. That is bloody stupid especially if there is no defined on/off switch for MCAS.

 

I'd be confused in the circumstance of an un-commanded stick push given this lack of information on the system and I have near on 7,000 hours of stick time on God alone knows how many aircraft.

 

Cheers

 

 

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So,

 

All MAX8 and 9s grounded globally following a Trump Executive order and discussions between Boeing and the FAA. It seems Canada jumped the gun and followed the decision of earlier nations to take that step but now it is global.

 

About time. A degree of North American hubris seems to have been at work but at least they are now on the ground and will remain there until the problem is resolved properly.

 

Aircraft manufacturers can and have in the past rebounded from such situations but Boeing are going to lose serious money on paper and there will be some degree of reduced confidence in their newest aircraft. A new 777 is not far from release in fact the announcement was delayed by the Ethiopian cash. No idea if MCAS in on that airframe, somewhat less likely, the changes are evolutionary rather than revolutionary which the latter seems to describe the MAX despite Boeing protests. Best guess a marketing decision from the 777 team not wanting to be launching under a cloud of controversy with Boeing's name on it.

 

I began this thread saying jumping to conclusions with aircraft accidents is ill-advised but the similarities between two crashes were already evident and new data seems to reinforce that.

 

In air accident investigation the first suspect is always pilot error but when two in row that look the same happen suspicion moves to the aircraft.

 

Now need to wait for the full analysis and report.

 

Cheers

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Posted (edited)
2 hours ago, chrisg said:

So,

 

All MAX8 and 9s grounded globally following a Trump Executive order and discussions between Boeing and the FAA. It seems Canada jumped the gun and followed the decision of earlier nations to take that step but now it is global.

 

About time. A degree of North American hubris seems to have been at work but at least they are now on the ground and will remain there until the problem is resolved properly.

 

Aircraft manufacturers can and have in the past rebounded from such situations but Boeing are going to lose serious money on paper and there will be some degree of reduced confidence in their newest aircraft. A new 777 is not far from release in fact the announcement was delayed by the Ethiopian cash. No idea if MCAS in on that airframe, somewhat less likely, the changes are evolutionary rather than revolutionary which the latter seems to describe the MAX despite Boeing protests. Best guess a marketing decision from the 777 team not wanting to be launching under a cloud of controversy with Boeing's name on it.

 

I began this thread saying jumping to conclusions with aircraft accidents is ill-advised but the similarities between two crashes were already evident and new data seems to reinforce that.

 

In air accident investigation the first suspect is always pilot error but when two in row that look the same happen suspicion moves to the aircraft.

 

Now need to wait for the full analysis and report.

 

Cheers

 

I've watched enough Air Crash to know, faults in planes get left there long enough ... like years until people start getting killed. Some problems just take longer to surface and then coverups happen for years just to avoid getting stuff fixed.

Edited by Jeruselem

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Some faults are subtle J, some are dependent upon flight cycles, some are maintenance related. some are sort of begging to rear their head, some are pilot error and some are training related. Then there are acts of God...

 

Subtle would be as an example the one that broke the until then fatal crash-free record of the 747. Lufthansa out of Nairobi, a valve not set correctly prevented deployment of the leading edge slats and the aircraft stalled when leaving ground effect. No real sequence of failures was ever established but Boeing improved the warning systems for the crew anyway. That was a 747-100 with three crew, the FE was probably at fault but the system needed improvement anyway. With currently flying 747s with two crew and glass cockpits in the main that one should never reoccur. A 747 captain once told me that had probably happened before but Nairobi is a high field, slats were essential to get enough lift in the thinner air. That or a longer run but the Vxx bugs were set for slat use speeds.

 

Flight cycles obviously the Comet, those square windows and metal fatigue not then being well understood. There have been others, the one in Hawaii, a 737 that lost part of the roof. Well within flight hours but lots of short trips.

 

Maintenance, a dismaying list but the BAC-111 that nearly sucked the captain out of the windscreen sticks in my mind. Wrong sized bolts used to secure a replacement screen.

 

This one is probably going to be begging to happen but what I do not understand if it is proven to be the MCAS  how the issue slipped past Boeing testing and FAA certification.

 

Pilot error far too many unfortunately, pilots make mistakes no matter how good they are. But some are attributed to the pilot when other factors were in the mix.

 

Training again quite a few, those early 727 accidents I mentioned for example. Deep stall is now well understood, it was not then but the manual should have been more forthright and training should have stressed the danger. I well recall watching Ansett and TAA 727s landing in Adelaide well after the dangers were understood. TAA flew a much flatter approach, Ansett more nose high but at higher power levels - two different ways to avoid deep stall. (Deep stall is in essence the high tail being blanked by the AoA, Ansett did not approach that steep but kept more power in hand anyway.)

 

Act of God, obviously a 747 eating volcanic dust but you could add wind sheer to that item, and others, so long as you include weather as an act of God and not human error.

 

There are doubtless other cause definitions but those are the main ones.

 

Have I ever made what could have been a fatal mistake ?

 

Of course and not just in military flying where you do push the envelope.

 

A descent through cumulo nimbus to get into Islo Do Sal in a -125 will always stick in my mind, never do that again.

 

Cheers

 

 

 

 

 

 

 

 

 

 

 

 

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So the flight recorders are going to France not the U.S. for analysis.

 

Unusual with a U.S. aircraft but understandable, France being the essential home of Airbus they have much more experience with FBW commercial aircraft.

 

Suggesting Ethiopia is suspecting the NTSB of Boeing bias is scurrilous, the agency is sending officers to France to work on the analysis but the media loves to throw mud...

 

Cheers

 

 

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52 minutes ago, chrisg said:

So the flight recorders are going to France not the U.S. for analysis

 

Yes, but with Boeing et al trouting on how safe the aircraft actually is, then with additional reports from pilots indicating  "Something Scrwwy, Wabbit", personally I'd be inclined to have a presumably (hopefully/probably/maybe?) unbiased eye cast over the autopsy results...

 

And considering King Crackpot (sorry, Trump) has even weighed in with issuing the grounding order for the US it might be a case of Cry Wolf, buuuut for him to stick his head up above the parapet potentially casting aspertions on a wondeful American company something had to have triggered him to Extractus Cranium and act in a helpful manner to all 'n sundry for once.

 

Even if the autopsy exam is biased then Boeing will have to push even harder to either prove "It's Not Our Fault" and/or better yet fix any problems properly in a timely manner.

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https://www.dailymail.co.uk/news/article-6803041/Boeing-software-update-fix-Max-8-nosedive-problem-delayed-government-shutdown.html

 

Well well, apparently there was software fix for the nose diving in autopilot mode!

...

 

A Boeing software update to fix a suspected nosedive problem in its 737 Max 8 jets was delayed by the US government shutdown, it has been claimed.

The safety fixes were reportedly slated for announcement as early as January in the wake of October's Lion Air disaster in Indonesia which claimed 189 lives.

But Boeing has now said its updates will happen 'in the coming weeks.' 

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Posted (edited)

Good to see you around Merlin 🙂

 

Yeah, no company is going to declare their product is unsafe but as much as Boeing wriggle the evidence is more than sufficient to ground the fleet.

 

Trump, well, anything to keep eyes off his investigations I guess, he even stuck his head into the debacle of Brexit claiming he gave advice to another person with her head up her ass -  Theresa May.

 

I took part in a brainstorm session with a bunch of pilot mates online last night.

 

It became a form of regression analysis, if the MCAS did not cause the crash what could have ?

 

Leave aside any human factors, the captain's last call was he was having flight control issues and wanted to RTB.

 

So within reasonable doubt unlikely to be pilot error, accepting that the crew may not have been fully aware of the operation of the MCAS it being automatic. Likewise not an attempted hijack, very unlikely to be sabotage and no claims of responsibility.

 

Discount birdstrike, most any pilot would have called it as just that, not control problems.

 

Training, quite possibly but that goes to Boeing's inadequate manual and extravagant claims about the commonality of the aircraft to earlier models. One current 737 pilot on -700s and two former on the same model had taken a look at the MAX manual and said it would lull them into a false sense of familiarity and gave them no indication that MCAS was anything to be much aware of - just another background system doing its' own thing, one remarked.

 

Some other control failure ? No one could think of one that would cause  an oscillation condition apart from trim runaway over-ride, which is the suspect, or just possibly engine surge but that is not borne out by the evidence, it is CofG not thrust line that MCAS is supposed to address.

 

Act of God ? Not unless the big guy likes to use MAX' as yo-yos. Weather in the area was pretty good and no out of the ordinary reports at all.

 

In short the discussion kept  returning to what could be done in the time available to deal with runaway MCAS when it was not a flag item in the manual to be aware of and when the damned thing was programmed to keep kicking back in if it was getting erroneous input. No one thought there would be enough time to sort out pulling the little appreciated circuit breaker, possibly even if there was an awareness of it being the key to disabling the false control input.

 

The key comment is "erroneous input." Similar to the Air France loss a sensor must have been giving false input, but, there is, unlike with the Airbus loss, not even any real sensor redundancy.

 

So that is sort of maintenance in a way as suspected actual primary cause but the system and the manual were still condemned. Pilots all, everyone wondered how much attention the maintenance manual pays to the MCAS sensor(s).

 

Seven pilots, combined command time well over 100,000 hours, all rather pissed off with Boeing and sadly sympathetic to the poor crews of both lost aircraft.

 

Cheers

 

Edit: not sure on that J, sounds like more Boeing wriggle if correct. The original date set by Being to have a fix was April, still is. Saying they were going to announce in January could mean anything, including on track for April. Doubt Trump will react nicely if he is made aware 🙂

 

 

 

 

 

 

 

 

Edited by chrisg

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26 minutes ago, Jeruselem said:

"A Boeing software update to fix a suspected nosedive problem in its 737 Max 8 jets was delayed by the US government shutdown, it has been claimed."

 

its unclear in that article who is responsible for that messaging, but it seems like a dumb idea.

 

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