Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi - Impact on Boeing 737 MAX

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Poiu
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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by Poiu » 11 Mar 2019, 09:49

Conti764 wrote:
11 Mar 2019, 09:19
From what I gather from the internet, it might not be a design flaw in the 737MAX but more of a hiatus in the manual and/or a lack of training to pilots regarding the MCAS...?
Not maxed yet, so member 737MAX is maybe a better person to answer the question, but as from what I read, pilots don’t have control over MCAS, that is why there is no mention about it in the manual.

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luchtzak
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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by luchtzak » 11 Mar 2019, 10:47

luchtzak wrote:
11 Mar 2019, 02:18
Chinese authorities have temporarily grounded the Boeing 737 MAX 8 aircraft on all their domestic routes, Cayman Airlines has grounded both aircraft.

https://www.aviation24.be/manufacturers ... lows-suit/
Ethiopian Airlines also decided to ground their Boeing 737 MAX aircraft.

Luke777
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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by Luke777 » 11 Mar 2019, 11:09

So in simple words, the new bigger eco engines changed the specs of the 737 in a way that could cause problems , but boeing worked around this by adding MCAS software, and this would be so easy to deal with that not even extra training should be necessary ? right ?

Bracebrace
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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by Bracebrace » 11 Mar 2019, 11:47

Luke777 wrote:
11 Mar 2019, 11:09
So in simple words, the new bigger eco engines changed the specs of the 737 in a way that could cause problems , but boeing worked around this by adding MCAS software, and this would be so easy to deal with that not even extra training should be necessary ? right ?
The problem has always been there since the classic (high by-pass ratio engines overpowering the limited elevator authority in low speed - high AOA phases) and has become worse with increasing engine power and moving the engine more forward with every upgrade (classic > NG > max). It has caused crashes in the past (Turkish NG in Amsterdam). Boeing decided to add a protection measure (this is not the only system interfering with the trim BTW, so does the speed trim system). The problem now is - if this is the cause - that the protection caused more deaths than the original problem.
Last edited by Bracebrace on 11 Mar 2019, 11:49, edited 2 times in total.

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Conti764
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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by Conti764 » 11 Mar 2019, 11:48

Poiu wrote:
11 Mar 2019, 09:49
Conti764 wrote:
11 Mar 2019, 09:19
From what I gather from the internet, it might not be a design flaw in the 737MAX but more of a hiatus in the manual and/or a lack of training to pilots regarding the MCAS...?
Not maxed yet, so member 737MAX is maybe a better person to answer the question, but as from what I read, pilots don’t have control over MCAS, that is why there is no mention about it in the manual.
One specific article mentions (some) pilots don't even know it's there so they react like in a 737NG which would contradict the MCAS and put the aircraft in jeopardy. But it's one article I've read it in and it dates from right after the Lion Air incident so maybe that issue is handled now...

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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by sn26567 » 11 Mar 2019, 12:06

The black boxes have been recovered.

After China, Ethiopia, Cayman Islands, now Indonesia too is suspending the 737MAX, but Boeing doesn't feel the need to issue new instructions. It must be a PR nightmare for them right now!
André
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Luke777
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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by Luke777 » 11 Mar 2019, 12:41

Thx for your explanation Bracebrace; right to the point !! but indeed.. if...this system was responsible, that is not known yet, and i doubt if the giants in this industry will ever admit if something would point is this direction

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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by jan_olieslagers » 11 Mar 2019, 12:46

For those who, like myself, wondered what MCAS stands for, here is what wikipedia says (be aware that this is unofficial and unreferenced information!):

Maneuvering Characteristics Augmentation System, a stall protection system suspected of playing a role in the Lion Air Flight 610's crash

Not very clear what was "augmented" in this case - if anything.


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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by 737MAX » 11 Mar 2019, 13:51

Poiu wrote:
11 Mar 2019, 09:49
Conti764 wrote:
11 Mar 2019, 09:19
From what I gather from the internet, it might not be a design flaw in the 737MAX but more of a hiatus in the manual and/or a lack of training to pilots regarding the MCAS...?
Not maxed yet, so member 737MAX is maybe a better person to answer the question, but as from what I read, pilots don’t have control over MCAS, that is why there is no mention about it in the manual.
MCAS is definitely known to MAX pilots today as Boeing published a bulletin about this shortly after the Lion Air crash. But... MCAS or not, the way "unreliable airspeed" and "runaway stabilizer" should be treated remains the same.

Inquirer
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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by Inquirer » 11 Mar 2019, 14:18

I read online that this MCAS thing is just a mechanical fix to push the nose down in case of a stall at certain high thrust settings, something which the 737Max is prone to because of the fact it has much more powerful engines which are positioned way too much forward versus what the wing and the tail were originally designed for.

It's undoubtably true that the 737max has very big engines which entirely hang in front of its wing, rather than (mostly) under it like on other planes and definitely like on the original 737, so that must have an impact on the way this plane is to be handled when at full thrust.

MCAS itself seems to be very elementary engineering, with just a simple sensor imput and a straight mechanical output logic which does not seem to interpret the validity of the imput in the first place, nor does it seem to have any automatic sensor redundancy to cope with even a single faulty sensor...

Is the MAX indeed taking the 737 platform itself too far out of its comfort zone?
Is that why the MCAS is there, to help keep this plane fly safely?
Shouldn't MCAS have been designed far more intelligently then, like on the competing Airbus planes?
To me MCAS seems more like something an undergraduate came up with than a certified solution to a life-threatening weakness in the design by a global aviation firm like Boeing!

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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by sn26567 » 11 Mar 2019, 15:23

Luke777 wrote:
11 Mar 2019, 12:41
Thx for your explanation Bracebrace; right to the point !! but indeed.. if...this system was responsible, that is not known yet, and i doubt if the giants in this industry will ever admit if something would point is this direction
Do you really think that NTSB, which has sent four experts on site, will let itself be influenced by Boeing, General Electric or any manufacturer of airframes and engines?

The black boxes have been recovered, and they will for sure shed some lights on what happened. The FR24 data already show some instability in the ascending speed after takeoff.

The black box recovered after the Lion Air crash revealed that this aircraft has had stability problems during the four flights preceding the crash, one of them including a loss of 9000 feet in a few seconds needing a repair during the 12 hours the aircraft was AOG. During its last flight, the aircraft plunged 24 times in 13 minutes, and each time (except the last) the crew managed to get the aircraft back in a horizontal position.

At the time, the cockpit crew were not sufficiently informed of MCAS. Ethiopian pilots should have known by now!
André
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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by jan_olieslagers » 11 Mar 2019, 15:28

Do you really think that NTSB, which has sent four experts on site, will let itself be influenced by Boeing, General Electric or any manufacturer of airframes and engines?
YES

Or, more precisely, they won't even need to be influenced. If they find any room for blame on the design, they will word it as softly as ever possible. Mind you, IF they do! It is not sure at all that any blame on the design is possible; we must not jump to conclusions.

But US'ans are very patriotic, as a nation; these state employees will do all they can to avoid blame on one of their country's star companies.
Last edited by jan_olieslagers on 11 Mar 2019, 16:04, edited 1 time in total.

ZavCity
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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by ZavCity » 11 Mar 2019, 15:45

Boeing has had a drop of 10% on Wall street.More bad news could be a disaster for them..So MAYBE the results of the "black" boxes could be of "influenced"..
gtz
paul

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luchtzak
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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by luchtzak » 11 Mar 2019, 15:53

ZavCity wrote:
11 Mar 2019, 15:45
Boeing has had a drop of 10% on Wall street.More bad news could be a disaster for them..So MAYBE the results of the "black" boxes could be of "influenced"..
Why should you do that ? The results are examined independently, right?

Bracebrace
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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by Bracebrace » 11 Mar 2019, 15:55

737MAX wrote:
11 Mar 2019, 13:51
MCAS or not, the way "unreliable airspeed" and "runaway stabilizer" should be treated remains the same.
That's a very confusing post...

Unreliable airspeed asks for a specific pitch target (pitch change using the yoke) and throttle selection (thrust change) and no actions with the trim system itself. You don't interfere with the trim system itself.

Runaway stabilizer on the other hand calls for yoke to regain control and activate the yoke cutout switches (no specific pitch target), AT disconnect (no thrust change) and further actions dealing with the trim system itself to de-activate it's function partially or completely.

Two completely different procedures. What goes first? Or only one? Confusing.

If this is the second crash, it is pretty clear there is a problem with the "failure identification". Confusion again.

If the thing is in there, pilots should be informed and have a function demo so they can at least identify what is happening. Confusion is not a problem behind a desk if you have hours and hours to study the case. Confusion is to be avoided at all times inflight. Confusion about failures, confusion about procedures, .... not good.

Luke777
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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by Luke777 » 11 Mar 2019, 17:11

jan_olieslagers wrote:
11 Mar 2019, 15:28
sn26567 wrote:Do you really think that NTSB, which has sent four experts on site, will let itself be influenced by Boeing, General Electric or any manufacturer of airframes and engines?
YES
also Yes ! Remember it is a billion dollar industry !! Even when (worst case scenario) NTSB should point at malfunctions of these newly added systems as a cause, this big industry will react with '' actions have been taken with a total review and new versions of software have been installed on all MAX 8's'' case closed....
Last edited by sn26567 on 11 Mar 2019, 17:14, edited 1 time in total.

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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by sn26567 » 11 Mar 2019, 17:17

Luke777 wrote:
11 Mar 2019, 17:11
jan_olieslagers wrote:
11 Mar 2019, 15:28
Do you really think that NTSB, which has sent four experts on site, will let itself be influenced by Boeing, General Electric or any manufacturer of airframes and engines?
YES
also Yes ! Remember it is a billion dollar industry !! Even when (worst case scenario) NTSB should point at malfunctions of these newly added systems as a cause, this big industry will react with '' actions have been taken with a total review and new versions of software have been installed on all MAX 8's'' case closed....
And that's where the lawyers start to intervene. Boeing has made mistakes, people have died, lawyers smell money and propose to families of victims to start a multi-million dollar suit, of which they will take 50% if they win! And those lawyers will spend huge amounts of money to prove that Boeing is the culprit.
André
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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by luchtzak » 11 Mar 2019, 17:51

The list is growing:
  • all Chinese carriers operating Boeing 737 MAX (96)
  • Cayman Airlines (2)
  • Ethiopian Airlines (4)
  • all Indonesian carriers: Lion Air (10) and Garuda Indonesia (1)
  • Royal Air Maroc
  • MIAT Mongolian Airlines (1)
  • Comair (1)

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Re: Ethiopian Airlines Boeing 737 MAX crashes between Addis Ababa and Nairobi

Post by Themax » 11 Mar 2019, 18:04

Bracebrace wrote:
11 Mar 2019, 15:55
737MAX wrote:
11 Mar 2019, 13:51
MCAS or not, the way "unreliable airspeed" and "runaway stabilizer" should be treated remains the same.
That's a very confusing post...

Two completely different procedures. What goes first? Or only one? Confusing.
If you're dealing with both problems, then do both procedures. Personally I would deal with the IAS disagree first, disconnect autopilot, autothrottle, turn off flight directors and fly the aircraft in pitch/thrust until you identify the malfunctioning airspeed indication.

While flying manually (or on autopilot), if there is uncommanded stabilizer movement, then you're dealing with a stab trim runaway --> apply memory items. Basically, disconnect all automatics, if the problem persists, switch the trim off with both cutout switches, and if the problem still persists, grasp the trim wheels manually.

The MCAS system has no "mechanical output" or doesn't "push the nose down", it only gives commands to the stabilizer trim actuators while flying manually. So you see your trim wheels starting to turn nose down, to compensate you will progressively need to pull harder on the yoke, and the movement continues until you don't have any more pitch autorithy to counteract this trim input. Pressing a trim switch on your yoke will inhibit the MCAS system for a few seconds. And if the system still doesn't stop --> stab trim runaway checklist -> kill stab trim inputs.

This was the issue for the Lionair accident. A Boeing bulletin has been issued to inform all crews of the possible issue and the procedures to counteract this issue (what I explained above).

Let's not speculate about what happened to the Ethiopian, as there is no information yet. There are many possible problems can cause trouble maintaining a steady climb after take off.

Greetings from a MAX flyer.

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