Ethiopian Airlines plane crashes on way to Nairobi

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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by ArthurDent » Mon May 27, 2019 11:07 am

Wayne Boonzaier wrote:
Wed May 22, 2019 9:04 pm
After reading all of the posts on this thread there is only one solution that makes any sense to to fix an automation problem and that is Jims suggestion that there should be a "Cub Mode" switch that disengages all the automation and gives full control to the pilots of every primary and secondary flight control from throttles to rudder and stick and trim.

After the first uncommanded nose down push the pilots would have hit the "Cub Mode" switch and flown the aircraft manually the rest of the way and no one would have died.

When the computer becomes a psychotic killer switch it off and fly the aeroplane.
That would be good if automation wasn't the layer that it has become between the pilot and the aircraft. As long as you require hydraulic actuators to move control surfaces and have wires/optic fibres carrying commands to those actuators, there can be no such switch.

Automation and modern envelope protection saves more lives than it takes and it will continue to do so while airlines believe that all pilots are equal, proper stick and rudder training is a waste of time and experience shouldn't be rewarded.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by heisan » Mon May 27, 2019 11:18 am

ArthurDent wrote:
Mon May 27, 2019 11:07 am
Wayne Boonzaier wrote:
Wed May 22, 2019 9:04 pm
After reading all of the posts on this thread there is only one solution that makes any sense to to fix an automation problem and that is Jims suggestion that there should be a "Cub Mode" switch that disengages all the automation and gives full control to the pilots of every primary and secondary flight control from throttles to rudder and stick and trim.

After the first uncommanded nose down push the pilots would have hit the "Cub Mode" switch and flown the aircraft manually the rest of the way and no one would have died.

When the computer becomes a psychotic killer switch it off and fly the aeroplane.
That would be good if automation wasn't the layer that it has become between the pilot and the aircraft. As long as you require hydraulic actuators to move control surfaces and have wires/optic fibres carrying commands to those actuators, there can be no such switch.

Automation and modern envelope protection saves more lives than it takes and it will continue to do so while airlines believe that all pilots are equal, proper stick and rudder training is a waste of time and experience shouldn't be rewarded.
The irony of it is that the 737 (even the MAX version) is probably the last production airliner that has, effectively, a 'cub mode'. While it does have hydraulic controls, they are still manipulated directly from the control column. All computer driven controls can be disabled with three actions (auto pilot disconnect, auto throttle disconnect and trim cut-off).

I doubt that any future airliner will ever have this level of direct pilot control again.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by ArthurDent » Mon May 27, 2019 11:54 am

heisan wrote:
Mon May 27, 2019 11:18 am
The irony of it is that the 737 (even the MAX version) is probably the last production airliner that has, effectively, a 'cub mode'. While it does have hydraulic controls, they are still manipulated directly from the control column. All computer driven controls can be disabled with three actions (auto pilot disconnect, auto throttle disconnect and trim cut-off).

I doubt that any future airliner will ever have this level of direct pilot control again.
That is not entirely true though, as the 737 has extensive pitch feel systems which cannot be disengaged.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by heisan » Mon May 27, 2019 12:14 pm

ArthurDent wrote:
Mon May 27, 2019 11:54 am
That is not entirely true though, as the 737 has extensive pitch feel systems which cannot be disengaged.
But it is still a direct mechanical/hydraulic feel system. At worst the computer can enable a 'x4' valve, which makes the pitch feel 4x heavier - but that is the closest the computers can come to manipulating the feel.

(Without some sort of feel system, the pilots would likely rip the wings off the first time one of them sneezed... The 737's mechanical-hydraulic system is probably the closest you can come to true control feel on a hydraulic system - without directly involving computers.)
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by heisan » Mon May 27, 2019 9:47 pm

It is actually interesting looking at the bits and pieces that have come out in the senate hearings...

Still need to read between the lines a lot (not much of the critical stuff gets released publicly), but it seems the actual mistake (if you can call it that) was in the FMEA analysis of the MCAS system - and that there is a tiny hole in the FAA certification system there...

Once the basic functional design for something like MCAS is complete, reliability and certification engineers do an FMEA (Failure Mode and Effects Analysis) on the design. This looks at all the possible failure modes of the new system, and how they affect the safety of the aircraft. Systems that are classified as high risk get redundancy, alerts and all the bells and whistles. Ones that are classified low risk get no monitoring or cross checks.

The mistake was that MCAS was evaluated with too low a risk. The low risk meant that the system would end up being implemented without redundancy or alerting.

This mistake in the FMEA should have been caught in the internal or external (FAA) review. I have no idea why the internal review missed it, but the hole in the Swiss cheese was at the FAA - they claim not to have done a detailed analysis of the MCAS implementation, because the system was not flagged as high risk...

So, one single mistake in the FMEA resulted in (1) MCAS being implemented without redundancy, and (2) the FAA not doing a detail review of the MCAS implementation.

It should not be possible for one mistake to result in a dangerous chain like this - I assume the final result will be a better review system for the FMEA itself in future.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by jimdavis » Mon May 27, 2019 10:24 pm

Methinks the FAA have failed badly and are now going to overreact and do their best to ground the aircraft for as long as possible. Their relationship with Boeing has been far too cosy and it has now soured into serious bad blood between them.

That is not necessarily fact - it's just how it looks to me.

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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by tansg » Tue May 28, 2019 6:14 am

heisan wrote:
Mon May 27, 2019 9:47 pm
It is actually interesting looking at the bits and pieces that have come out in the senate hearings...

Still need to read between the lines a lot (not much of the critical stuff gets released publicly), but it seems the actual mistake (if you can call it that) was in the FMEA analysis of the MCAS system - and that there is a tiny hole in the FAA certification system there...

Once the basic functional design for something like MCAS is complete, reliability and certification engineers do an FMEA (Failure Mode and Effects Analysis) on the design. This looks at all the possible failure modes of the new system, and how they affect the safety of the aircraft. Systems that are classified as high risk get redundancy, alerts and all the bells and whistles. Ones that are classified low risk get no monitoring or cross checks.

The mistake was that MCAS was evaluated with too low a risk. The low risk meant that the system would end up being implemented without redundancy or alerting.

This mistake in the FMEA should have been caught in the internal or external (FAA) review. I have no idea why the internal review missed it, but the hole in the Swiss cheese was at the FAA - they claim not to have done a detailed analysis of the MCAS implementation, because the system was not flagged as high risk...

So, one single mistake in the FMEA resulted in (1) MCAS being implemented without redundancy, and (2) the FAA not doing a detail review of the MCAS implementation.

It should not be possible for one mistake to result in a dangerous chain like this - I assume the final result will be a better review system for the FMEA itself in future.
Not as simple as that as with all accidents there are a number factors all which have been discussed on this thread but yes the the FMEA did fail to identify the problem, which ended up as the root cause of failure which, was an unverified erroneous data input into a safety critical system which then caused unintended extreme automatic maneuvres by the aircraft which unprepared aircrew were not able to resolve before they impacted the ground. Of course there were are lot of extenuating circumstances, failure of the FMEA being one of them, insufficient training being another, etc, all which contributed to the alignment of the holes of John Reason's model, causing the above scenario to occur.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by henkhugo » Wed May 29, 2019 10:57 am

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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Ugly Duckling » Fri May 31, 2019 8:07 am

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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Lowaldo » Sat Jun 01, 2019 9:55 am

Fresh out of Sim....eye opener WRT to Trim related procedures etc which could have given these guys some chance of surviving...if only it was not hidden so much in the QRH!
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by dollar » Mon Jun 03, 2019 9:40 am

I saw a news item today about another problem found. Something about some of the slats not being made correctly, but it shouldn’t impact the return to service.

FAA are probably examining every nut and bolt on these aeries!

As others have said, a series of holes. I bet there were a couple of smart engineers at Boeing that were very uneasy after Lion Air. But it was not only an engineering problem but a commercial problem as well. Or so they thought. Like the space shuttle O rings, they were aware of the problem but all involved thought they had managed it “satisfactorily”.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Stephan van Tonder » Mon Jun 03, 2019 11:11 am

I recon once these return to service they will be pretty safe. probably very few aircraft would have been scrutinized like that in a while.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Hop Harrigan » Mon Jun 03, 2019 5:12 pm

dollar wrote:
Mon Jun 03, 2019 9:40 am
I saw a news item today about another problem found. Something about some of the slats not being made correctly, but it shouldn’t impact the return to service.

FAA are probably examining every nut and bolt on these aeries!

As others have said, a series of holes. I bet there were a couple of smart engineers at Boeing that were very uneasy after Lion Air. But it was not only an engineering problem but a commercial problem as well. Or so they thought. Like the space shuttle O rings, they were aware of the problem but all involved thought they had managed it “satisfactorily”.
Here it is:

https://www.cnn.com/2019/06/02/business ... index.html

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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by jimdavis » Wed Jun 19, 2019 9:33 am

Very good news for Boeing. From Avweb:

Despite having been grounded since March and a profound lack of recent orders for Boeing’s beleaguered 737 MAX, good news arrived at the Paris Air Show as the International Airlines Group (IAG) and Boeing announced signing a letter of intent for 200 of the single-aisle jets. IAG is the parent company of Aer Lingus, British Airways and Iberia, among others. The value of the deal is said to be $24 billion.

The order is something of a coup for Boeing, not only because it’s an important industry signal that faith in the MAX can be restored. Currently, IAG’s single-aisle fleet is made up of Airbus A320 models almost exclusively, so orders for the 787 MAX 8 and MAX 10 aircraft, which seat as many as 230 passengers, portray an important recovery for Boeing in the segment. The aircraft will be delivered between 2023 and 2027.

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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by richard C » Wed Jun 19, 2019 9:57 am

Wow, where are they going to park them all ?
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