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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 14th Mar 2019, 19:58
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Originally Posted by dsc810
...and their customers are exactly the same
They know the low cost cheap flights risk a monumental mess up every now and then that leaves them stranded for XX hours in some ghastly place
But they also just hope the odds work in their favour and its not them that get caught.
Its the same everywhere: people complaining how some corporate is cutting services or not doing it "properly" while the same complainers are busy bodging up their electrics, roof, guttering whatever and hope the next purchaser does not notice.
The airline "customers" are often not those flying at all, but corporate central beancounter staff making bookings for their staff on what is the cheapest fare to the destination, regardless of other considerations. The staff actually flying end up just stuck with the choice. Certain carriers have made a whole market out of this ...

Some corporates are better at this than others. There is a general belief that oil companies, well used to very substantial Due Diligence of their helicopter operators, let this approach go through to the comercial airline bookings for their staff as well, who to use and who not. Others not so much. It's notable that a significant number of the Ethiopian passengers were travelling for a major worldwide organisation, who possibly procure their air tickets centrally.

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Old 14th Mar 2019, 20:20
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Originally Posted by SquintyMagoo
cervo77 asks "How should they know that pulling on the Yoke didn’t stop the trim?"

Shouldn't they hear or notice the trim wheel continuing to turn?
Yes.

filler
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Old 14th Mar 2019, 20:23
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Originally Posted by oldoberon
Surely BEA are responsible for recovering data not analysing
The BEA are responsible for whatever they have agreed to do on behalf of the ECAA who are leading the investigation.

I would be amazed if their remit did not include initial analysis of the recovered data. After all, that's what the 'A' in BEA stands for.
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Old 14th Mar 2019, 20:23
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Is there an airspeed input component to MCAS ?
http://www.b737.org.uk/mcas.htm
this mentions “at airspeed approaching stall”

I wondered because we know there was likely an UAS situation for ET, so potentially a pitot hardware issue.
If AoA was all that MCAS received , then we’d be looking at possible alpha vane failure as well, therefore we’d have hardware issues with two separate components.

So - could a blocked pitot be another single point of failure? And the AoA was fine?....
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Old 14th Mar 2019, 20:32
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Originally Posted by oldoberon
Ian I assume you read all of the narratives.

A few quick points from memory
Pilots not being able to usual scan and see what they are looking for
Pilots not familiar with new displays
Pilots not Knowing what the "Maint" msg means and unable to find it in pilots notes
Pilots not knowing what a particular switch labelled SEL was for.

That is abysmal conversion training (classroom and sim) , abysmal documentation and DANGEROUS
If those points are correct then how were they even flying the aircraft? The airline involved is responsible for ensuring conversion to type and should ensure that the crews are trained and tested. If the Boeing difference and conversion is insufficient then Boeing needs to be told. Then surely simple self preservation if you are put into a new cockpit and cannot 'scan and see what you are looking for' not find switches read displays or know what switches are for.... I would expect that crew to not fly the aircraft. That they did indicates something very very wrong at the airline involved. It seems we are starting to see the impact of the beancounters on flight safety and/or perhaps - if you are right either a gung-ho approach from some crews or an unwillingness to stand above the parapet and say I need more training for this one.

More to the point in both cases the aircraft were in good VFR at low level, speed should be apparent without looking inside so there is a visual cross check, the trim keeps going nose down - so switch off stab trim (AFAIK the switches are in the same place in all 73's) start using the trim wheel and fly manually and visually while PM goes through the various memory items and checklists. We know that this approach works as a Lion Air flight before the crash flight did just that and continued as a normal flight.
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Old 14th Mar 2019, 20:52
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Originally Posted by Joejosh999
Is there an airspeed input component to MCAS ?
737 MAX - MCAS
this mentions “at airspeed approaching stall”

I wondered because we know there was likely an UAS situation for ET, so potentially a pitot hardware issue.
If AoA was all that MCAS received , then we’d be looking at possible alpha vane failure as well, therefore we’d have hardware issues with two separate components.

So - could a blocked pitot be another single point of failure? And the AoA was fine?....
MCAS activation requires AOA above an activation level that is a function of Mach number. The dependence on Mach is not particularly significant (i.e., errant Mach would not significantly impact the MCAS activation point). The amount of stabilizer motion that MCAS will command is also a function of Mach number. With Mach less than 0.4 MCAS will move the stabilizer as much as 2.5 degrees if AOA exceeds the activation threshold by many degrees. At cruise Mach number the size of the MCAS stabilizer motion increment is less than 1/3rd that at low Mach numbers. The bottom line with regard to the question posed here is that a blocked pitot coupled with healthy AOA data would not cause MCAS to activate unless actual (and thus properly sensed) AOA increased to a level significantly above that for normal operation. If you follow pitch/power guidelines after pitot blockage and detection of unreliable airspeed you will not get MCAS. If you get slow and get to elevated AOA following pitot blockage you are likely to encounter MCAS provide flaps are up and autopilot is not engaged.
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Old 14th Mar 2019, 20:55
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Originally Posted by FCeng84
MCAS activation requires AOA above an activation level that is a function of Mach number. The dependence on Mach is not particularly significant (i.e., errant Mach would not significantly impact the MCAS activation point). The amount of stabilizer motion that MCAS will command is also a function of Mach number. With Mach less than 0.4 MCAS will move the stabilizer as much as 2.5 degrees if AOA exceeds the activation threshold by many degrees. At cruise Mach number the size of the MCAS stabilizer motion increment is less than 1/3rd that at low Mach numbers. The bottom line with regard to the question posed here is that a blocked pitot coupled with healthy AOA data would not cause MCAS to activate unless actual (and thus properly sensed) AOA increased to a level significantly above that for normal operation. If you follow pitch/power guidelines after pitot blockage and detection of unreliable airspeed you will not get MCAS. If you get slow and get to elevated AOA following pitot blockage you are likely to encounter MCAS provide flaps are up and autopilot is not engaged.
Thanks for the clarification!

So it’s possible we’ve had hardware failure in two separate components? Pitot and alpha vane?
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Old 14th Mar 2019, 21:04
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Originally Posted by Helix Von Smelix
Just looking at the Boeing 777-9 rollout photos. My question is, Have Boeing done a similar thing with the engine position on the 777-9 as they did with the 737-MAX? Forward and high.
They have actually lengthened the main gear legs to 16ft, the longest ever used on an airliner, but yes the diameter of the engine means that it does sit higher and farther forward.

Of course with the FBW 777 that should be less of a problem.

Trivium: the manufacturer of the 777X MLG, Héroux Devtek in Quebec, also supplied the legs for the Apollo Lunar Module.
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Old 14th Mar 2019, 21:09
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Old 14th Mar 2019, 21:33
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Originally Posted by DaveReidUK
After all, that's what the 'A' in BEA stands for.
After reading through all 12 of the AF 447 threads, I came away with the impression that some people felt that the A in BEA stood for Airbus.

For PJ2: I have an idea that there are some corporate cultures that might need to awaken to training being viewed as a necessity, rather than as an expense, or a cost center. Which corporate (or even national) entities that message needs be to be digested in I'll leave as an exercise for the reader.

For someone further up the page: off to take a look at the LionAir FDR trace, thanks for the tip.

For anyone, last question.
MTBF of AoA probes. Who is Boeing's supplier? (If the AoA prob, or its signal to the FCC, doesn't go whacky do we ever hear about any of this?)
We had a fairly long discussion about pitot tubes after AF447 went down, and commentary about Goodrich probes that AB was working on putting on their fleet versus a Thales one. Are AoA probes held to the 1 x 10^-7th hours failure criteria, or a 1 x 10 ^-9?
I don't know how good the final report on LionAir will be, but I am very interested in the prelude to that accident, in terms of what maintenance actions were and weren't taken, and how the trouble shooting logic went, and the various repairs.
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Old 14th Mar 2019, 21:51
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Originally Posted by Lonewolf_50
For anyone, last question.
MTBF of AoA probes. Who is Boeing's supplier? (If the AoA prob, or its signal to the FCC, doesn't go whacky do we ever hear about any of this?)
We had a fairly long discussion about pitot tubes after AF447 went down, and commentary about Goodrich probes that AB was working on putting on their fleet versus a Thales one. Are AoA probes held to the 1 x 10^-7th hours failure criteria, or a 1 x 10 ^-9?
I don't have that info, but as a general comment on sensor reliability, up-thread somewhere there is a post by a NG pilot mentioning that a bird strike took out an AoA vane on one of his recent flights. Obviously the sensor should have the highest possible MTBF, but the system as a whole needs a safe method to recover from a sensor that can be taken out that easily, and that randomly.
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Old 14th Mar 2019, 21:53
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Quote:
Originally Posted by cervo77
Then there are differences, and the Pilots should have been informed about the differences. Unfortunately the lion and Ethiopian's pilots have not had this chance

Originally Posted by hawk76
Apparently the Ethopian pilots did, according to CNN:

Quote:GebreMariam said the Ethiopian Airlines pilots had received additional training on the flight procedures involving the 737 MAX 8 after the Lion Air crash.

Apologies with the mess of the quoting above but the site doesn't help you multi-quote....

Channel 4 News (UK) has just screened an interview with a "Senior Ethiopian Pilot".

Note that: the interview was voice disguised and anonymous. The pilot did not state that then flew 737 MAX-8, or if they did, what experience they had on that airframe.

In the interview the pilot stated that the MCAS had not been taught to them [by Boeing]. He went on to talk about not being able to defeat the system by pulling on the stick. He did NOT mention adjusting trim [as a means to defeat the system].

Having read from the professionals above about having to use trim wheels or cutout switches to defeat MCAS, and NOT using the stick alone, my conclusion from the interview was that the pilot had NOT been trained in the correct procedures, or surely he would have mentioned it?

Of course it might be that C4 found a pilot that hadn't flown the MAX 8, but the C4 journalists are usually pretty professional and wouldn't put this interview forward if that were the case.
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Old 14th Mar 2019, 21:57
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Originally Posted by Photonic
I don't have that info, but as a general comment on sensor reliability, up-thread somewhere there is a post by a NG pilot mentioning that a bird strike took out an AoA vane on one of his recent flights. Obviously the sensor should have the highest possible MTBF, but the system as a whole needs a safe method to recover from a sensor that can be taken out that easily, and that randomly.
100% concur on system robustness requirement.
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Old 14th Mar 2019, 22:00
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Originally Posted by WHBM
You can actually find this increasingly with government Regulatory Authorities, in various countries, and with other regulators/augitors, eg for the finance industry.

Time was when the regulators were quite independent, and looked at things with true external oversight. They would need the knowledgeable personnel to work through everything. Then it slowly occurred to them that they might get the industry they were regulating to do certain of their jobs for them....<SNIP>
Yes, except that this was not something that "slowly occurred" to the regulators: it was a deliberate political decision for "light-handed regulation" and self-regulation, taken throughout Anglophonia, in the belief that the market would ensure that the regulated entities would want to keep their good reputation (for commercial reasons), and so could attend to the material aspects of regulation, without being stifled by "bureaucratic inertia." We now see the costs, in many industries, in lives that would not have been lost under the old regime.
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Old 14th Mar 2019, 22:08
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Originally Posted by Peristatos
.
(Two graphs of vertical speed).

Source: https://www.bloomberg.com/news/artic...-investigation




Interesting two graphs.
And of course the 21 second interval in vertical speed cycles, equates very nicely with 10 secs of MCAS trim input and 10 sects of manual trim resetting. Prima face evidence that MCAS was operating in this flight.

Silver
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Old 14th Mar 2019, 22:22
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Originally Posted by TBC Retired
777 was the last program I worked on at Boeing where I felt they did everything pretty much as it should be done. "Working Together" was the motto and that meant not just consulting with customers, but coordinating internally by having 'design/buil'' teams working with each other all the way rather than emerging from their individual tunnels at the end of the process to find miscommunications and things that didn't work together properly. After that program, Boeing dismantled their traditional design matrix organizations which served as checks and balances on each other, but required lots of staff. Later programs seemed to have lost that magic and each follow-on project was mandated to have a faster and cheaper design/build/test/certify cycle than the previous one. Most of the low hanging wasteful effort was eliminated long ago and it was value added activities that started being cut. I felt that trend culminated on the Max program which kicked off with a misguided dream by program leadership that they might actually be able to eliminate flight testing altogether because prediction methods and computational models were so accurate and mature. Pure hubris. Every program I ever worked on had unanticipated show stoppers which surfaced during flight testing and required panic fixes, yet that basic lesson seemed to have to be constantly relearned.
IMO, the day Alan Mulally left Boeing was the beginning of the end of "Working Together." I'm not surprised at Boeing's current situation. Look at the KC-46's being delivered with trash, and tools left in them. It's like WTF is going on? Seems like a dire situation IMO.
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Old 14th Mar 2019, 22:24
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Lion Air was deluged with heavy raid the night before the tragedy. Yes, I'm still looking for multiple glitches, that when combined cause chaos.

Those graphs seem too similar not to be very closely connected, but the similarity might be partly caused by human interpretation and resultant handling and not entirely by glitch sequences.
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Old 14th Mar 2019, 22:24
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The MCAS is there to stop the aircraft from stalling so why not call it a "stall avoidance system" ? If it walks like a duck and quacks like a duck, then it's a duck.

The B757 and B767 first flew 15 years after the B737 and are already out of production except for freighter and military versions of the B767.

The move from the B742 to B744 required an extensive redesign of the flight deck and systems, Boeing didn't just stick in a couple of TV screens in front of the pilots. The B737 should have had a similar in-depth redesign if they were going to continue with the same airframe, rather than the patchwork quilt of modifications and work arounds it ended up with.

It's a first generation jet modified into a third generation one.
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Old 14th Mar 2019, 22:35
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Originally Posted by silverstrata


Interesting two graphs.
And of course the 21 second interval in vertical speed cycles, equates very nicely with 10 secs of MCAS trim input and 10 sects of manual trim resetting. Prima face evidence that MCAS was operating in this flight.

Silver
We must be careful trying to read too much into very limited data. Remember that MCAS will not come active a second time until the pilot as been off of the trim input for 5 continuous seconds. For the Lion Air event data showing pilot and MCAS trim commands has been presented in that PPRUNE thread. It would be interesting to line that up with these plots to see how that particular cycle corresponded to pilot trim inputs. Hopefully we have access to the ET data soon to do the same for that event.
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Old 14th Mar 2019, 22:37
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Anyone know if Boeing has been able to duplicate the problem in flight testing?
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