Ethiopian airliner down in Africa
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Curtain Twitcher #2872
Thanks for the links; I have read some of the rationale for STAMP, but have difficulty in following the arguments.
Many similar safety initiatives tend to fall foul of hindsight; this is a limitation of this type of thinking - ‘what we could have done for this accident’. Alternatively with beneficial application in foresight, the successful intervention and system design might never be established, because we have not had an accident.
Retrospective safety - focus on accidents for learning, is increasingly limiting in design and operation, thus a forward looking ‘processes’ should improve safety, even if we never know that it has - we never see the accident avoided.
The limit in this approach remains with the human; however good the design and evaluation is, the question ‘have you considered this’ (an aspect of concern*), a human answer ‘yes’ has the rule. Whereas perhaps we need ‘Yyeeees, Probably’, and return to the evaluation - double loop learning, return to the assumptions.
The findings from this accident might identify the problems above (hindsight again), yet we must consider the influences in the existing safety process. Some of the designers and regulators might not have even been born at the time of the initial design and certification. Thus, what has been forgotten, assumption based complacency - does a good accident record bias judgement of the safety of future aircraft variants, whereas treating these as ‘new’ aircraft might question pertinent factors - grandfathers die, let them rest peacefully.
* a machine process designed by humans, subject to our limitations.
Thanks for the links; I have read some of the rationale for STAMP, but have difficulty in following the arguments.
Many similar safety initiatives tend to fall foul of hindsight; this is a limitation of this type of thinking - ‘what we could have done for this accident’. Alternatively with beneficial application in foresight, the successful intervention and system design might never be established, because we have not had an accident.
Retrospective safety - focus on accidents for learning, is increasingly limiting in design and operation, thus a forward looking ‘processes’ should improve safety, even if we never know that it has - we never see the accident avoided.
The limit in this approach remains with the human; however good the design and evaluation is, the question ‘have you considered this’ (an aspect of concern*), a human answer ‘yes’ has the rule. Whereas perhaps we need ‘Yyeeees, Probably’, and return to the evaluation - double loop learning, return to the assumptions.
The findings from this accident might identify the problems above (hindsight again), yet we must consider the influences in the existing safety process. Some of the designers and regulators might not have even been born at the time of the initial design and certification. Thus, what has been forgotten, assumption based complacency - does a good accident record bias judgement of the safety of future aircraft variants, whereas treating these as ‘new’ aircraft might question pertinent factors - grandfathers die, let them rest peacefully.
* a machine process designed by humans, subject to our limitations.
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oOftware design
Many years ago while working on a fire-control system, we were evaluating test methodologies between the F-16's Westinghouse, General Dynamics Phalanx fire-control, and Airbus fly-by-wire. The Airbus strategy (as I recall which was about 4 decades back) was to deliver the code to 3 companies in three different countries, none of whom knew of the others existence. AB expected each would find some unique code exceptions by doing so. Not so. Well over 90% were identifed by multiple vendors including all deemed critical bugs save maybe one. The rest were not considered major flight control errors.
Maybe Gums could chime in here, but we had heard rumors (maybe urban legend) that some of the early F-16 deployments in Germany with look-down did on occasion lock on to low flying Mercedes on the Autobahn. As a designer, how many would consider that possibility?
There will ever be a perfect balance between automation and human interaction. Automation is programmed by humans - mistakes will happen on both ends.
Maybe Gums could chime in here, but we had heard rumors (maybe urban legend) that some of the early F-16 deployments in Germany with look-down did on occasion lock on to low flying Mercedes on the Autobahn. As a designer, how many would consider that possibility?
There will ever be a perfect balance between automation and human interaction. Automation is programmed by humans - mistakes will happen on both ends.
Even assuming that the designer can clearly articulate and document what he wants the software to do in my experience, very rare), the coder then needs to understand what the designer wants. The coder then has his job spoiled by software tools claiming to produce rigourous code.He then needs to agree a test suite with the designer assuming it was not part of the specification.
The chances of this chain working are nil in practice. Even for simple things like software drivers for printers there are bugs.
The other core problem is that unless the broad design architecture is right from the beginning there is a limit to retrofitting new features before it becomes impossible to understand the interactions.
As a simple daily example, all cars have been fitted with the an OBD (on board diagnostics) system for decades and this allows diagnostics of all bits of the car including things like the heater as well as lights and brakes and all parts of the engine. This has been around for fifty years and I have three different diagnostic tools for three different cars. Each has bugs since the car systems have bugs and by all accounts ALL cars have bugs and this system is not only simple but its base architectural design is clean and the result of all manufacturers working together to set a standard architecture.It needs to be accepted that ALL planes have software bugs and the solution is simple - a LARGE red button that switches off ALL aids instantly and puts the control in the hands of the pilot instantly.
Might need some new training though
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.............
Maybe Gums could chime in here, but we had heard rumors (maybe urban legend) that some of the early F-16 deployments in Germany with look-down did on occasion lock on to low flying Mercedes on the Autobahn. As a designer, how many would consider that possibility?..........
.
Maybe Gums could chime in here, but we had heard rumors (maybe urban legend) that some of the early F-16 deployments in Germany with look-down did on occasion lock on to low flying Mercedes on the Autobahn. As a designer, how many would consider that possibility?..........
.
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I may be dancing around the same tree as in my post in the other thread - #485 Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed
Where is the value of AoA sampled by the FDR; would this clarify current understanding.
Where is the value of AoA sampled by the FDR; would this clarify current understanding.
Peter Leeme has previously suggested that MAX no longer has separate SMYD "box" - however he retracted that a couple of days ago in this post:
In prior posts I have postulated whether SMYD had become a function in the FCC on the MAX. I was wrong. The SMYD appears on the 737 MAX pretty much as the 737 NG. This is a significant realization. The AoA vane has one analog resolver output connected to the ADIRU, and one output connected to SMYD.
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Peter Lemme has previously suggested that MAX no longer has separate SMYD "box" - however he retracted that a couple of days ago in https://www.satcom.guru/2019/03/aoa-...oeing-fix.html
The response to a stabilizer runaway is to cutout the electric trim. Nowhere does anyone caution the consequences of using manual (turn the wheel manually) trim. The manual trim wheel can be very hard to turn if subject to high aero loads, and particularly if the elevator is commanded significantly (loading the stabilizer).
The standard response to just hit the stabilizer cutout switches and manually trim is actually flawed. If the nose has been pushed down by significant mistrim (nose down stabilizer, nose up elevator), and as airspeed increases, it may not be possible to trim the stabilizer manually nose up without letting the elevator go to a neutral position. The reality, under the MCAS runaway scenario, trimming nose up immediately stops MCAS as well as trims the stabilizer back towards an in-trim position. At that point, you would be best off to cutout the stabilizer.
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What I don't understand (well I do because building airplanes is all about keeping the costs down) is why they keep using these "obsolete" and fragile vane sensors.
Back in 1979 when we first got the F-16's we where all too happy to see "new" differential pressure activated AOA sensors. => But => But => And that is where it all goes dark => They are more expensive.
Back in 1979 when we first got the F-16's we where all too happy to see "new" differential pressure activated AOA sensors. => But => But => And that is where it all goes dark => They are more expensive.
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First the news said this:
And slightly later, the news said this:
..
So, the WSJ report earlier during the day appeared to be correctly describing what had happened behind the scene...
Patience is a virtue, or so they say...
Ethiopian Air Report on Boeing Plane Crash to Be Released Monday
And slightly later, the news said this:
No Ethiopia plane crash report on Monday, maybe this week: source
..
So, the WSJ report earlier during the day appeared to be correctly describing what had happened behind the scene...
U.S., Ethiopian Investigators Tussle Over 737 MAX Crash Probe
Patience is a virtue, or so they say...
I’ve flown with all types of instruments from dials to strip indicators. I find the strip ideal for cross cockpit engine value info during high thrust phases for instance, compared to dials - but can’t share your view that strip length is clearer than a pictorial representation for an AoA vane - or rather for the information it delivers.
Angle nose up / down is more easily seen on a dial display than a strip - which actually does in this situation require analysis - or at least interpretation.
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What I don't understand (well I do because building airplanes is all about keeping the costs down) is why they keep using these "obsolete" and fragile vane sensors.
Back in 1979 when we first got the F-16's we where all too happy to see "new" differential pressure activated AOA sensors. => But => But => And that is where it all goes dark => They are more expensive.
Back in 1979 when we first got the F-16's we where all too happy to see "new" differential pressure activated AOA sensors. => But => But => And that is where it all goes dark => They are more expensive.
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U.S., Ethiopian Investigators Tussle Over 737 MAX Crash Probe
Tension over access to and interpretation of data comes ahead of a preliminary report on what happened to the Boeing plane
Tension is simmering between U.S. and Ethiopian officials as investigators prepare to release in the coming days an interim report about the Boeing Co. 737 MAX jetliner that nose-dived after takeoff from Addis Ababa on March 10, according to people from both countries.
U.S. investigators, according to people familiar with their thinking, have privately complained that Ethiopian authorities have been slow to provide data retrieved from the black-box recorders of Ethiopian Airlines Flight 302, which went down minutes into a flight to Nairobi, killing all 157 people on board.
American air-safety officials also have described what they view as an aloof attitude among the Ethiopians toward other investigators and say the Ethiopians have provided often limited access to relevant crash information, these people said.
A spokesman for the Ethiopian transport minister didn’t respond to requests for comment Sunday. Ethiopians involved in the probe, for their part, have chafed at what they see as American efforts to exert control over the preliminary report, according to other people familiar with the investigation.
The behind-the-scenes maneuvering, according to people from both countries, has impeded but not prevented the international investigators from working together.
The preliminary crash report, according to people briefed on the details, is expected to say that data analyzed so far indicates the Ethiopian accident bears important similarities to the crash of a Lion Air 737 MAX plane that went down in Indonesia less than five months earlier, including activation of an automated stall-prevention system and related features.
Boeing is in the process of rolling out a software fix and enhanced training related to the automated feature, called MCAS.
Publicly, U.S. officials have expressed satisfaction with the sharing of information. Last Wednesday, Robert Sumwalt, chairman of the National Transportation Safety Board, which is leading U.S. participation in the probe, told a Senate subcommittee his experts have gotten the data they need.
On Sunday, a Boeing spokesman said: “We have great respect for the Ethiopian government. As a party to the investigation, we’re following all international protocols and conduct all our work through” the U.S. safety board.
From the outset, though, Ethiopian officials have kept tight control of the probe, carefully guarding the recorder data and pushing back at what they view as efforts by Boeing investigators to influence and speed up release of the preliminary report on the crash, according to people familiar with the matter.
The Boeing spokesman said it was “absolutely not true” that the company’s investigators are trying to influence or speed up the preliminary report.
Safety experts have also tussled over the interpretation of certain data and their presentation in the report, according to people from both countries.
Ethiopian officials asked the French aviation accident investigation bureau BEA, which downloaded data from the black boxes, to permanently delete that information from its servers once it had been transmitted to Ethiopian authorities. The BEA has confirmed complying with the request.
Frequently, probes of airline crashes that occur outside the U.S. in which American investigators play a role prompt friction and outright disagreements between U.S. government and industry experts and local investigators leading the probes.
In the case of Ethiopia, the tension is exacerbated by the country’s limited staff and experience investigating major airliner crashes, according to industry and safety experts tracking the probe.
Officials in Addis Ababa, for their part, are still smarting from the results of an investigation into the deadly 2010 crash of an Ethiopian Airlines plane shortly after takeoff from Beirut. That probe, led by Lebanese authorities, found that the airline’s pilots failed to respond adequately to stormy weather during the aircraft’s ascent. Ethiopia at the time disagreed with the findings of the investigation, attributing the crash to bad weather.
“With this investigation, we are the ones who are in charge,” the chief of Ethiopia’s civil aviation authority, Col. Wosenyeleh Hunegnaw, said in a March 20 interview.
Another potential point of friction, according to some people familiar with the details, is the role played by experts from state-owned Ethiopian Airlines, which also faces scrutiny in the probe. The airline’s engineers have been providing technical support to officials from Ethiopia’s transport ministry.
Tension over access to and interpretation of data comes ahead of a preliminary report on what happened to the Boeing plane
Tension is simmering between U.S. and Ethiopian officials as investigators prepare to release in the coming days an interim report about the Boeing Co. 737 MAX jetliner that nose-dived after takeoff from Addis Ababa on March 10, according to people from both countries.
U.S. investigators, according to people familiar with their thinking, have privately complained that Ethiopian authorities have been slow to provide data retrieved from the black-box recorders of Ethiopian Airlines Flight 302, which went down minutes into a flight to Nairobi, killing all 157 people on board.
American air-safety officials also have described what they view as an aloof attitude among the Ethiopians toward other investigators and say the Ethiopians have provided often limited access to relevant crash information, these people said.
A spokesman for the Ethiopian transport minister didn’t respond to requests for comment Sunday. Ethiopians involved in the probe, for their part, have chafed at what they see as American efforts to exert control over the preliminary report, according to other people familiar with the investigation.
The behind-the-scenes maneuvering, according to people from both countries, has impeded but not prevented the international investigators from working together.
The preliminary crash report, according to people briefed on the details, is expected to say that data analyzed so far indicates the Ethiopian accident bears important similarities to the crash of a Lion Air 737 MAX plane that went down in Indonesia less than five months earlier, including activation of an automated stall-prevention system and related features.
Boeing is in the process of rolling out a software fix and enhanced training related to the automated feature, called MCAS.
Publicly, U.S. officials have expressed satisfaction with the sharing of information. Last Wednesday, Robert Sumwalt, chairman of the National Transportation Safety Board, which is leading U.S. participation in the probe, told a Senate subcommittee his experts have gotten the data they need.
On Sunday, a Boeing spokesman said: “We have great respect for the Ethiopian government. As a party to the investigation, we’re following all international protocols and conduct all our work through” the U.S. safety board.
From the outset, though, Ethiopian officials have kept tight control of the probe, carefully guarding the recorder data and pushing back at what they view as efforts by Boeing investigators to influence and speed up release of the preliminary report on the crash, according to people familiar with the matter.
The Boeing spokesman said it was “absolutely not true” that the company’s investigators are trying to influence or speed up the preliminary report.
Safety experts have also tussled over the interpretation of certain data and their presentation in the report, according to people from both countries.
Ethiopian officials asked the French aviation accident investigation bureau BEA, which downloaded data from the black boxes, to permanently delete that information from its servers once it had been transmitted to Ethiopian authorities. The BEA has confirmed complying with the request.
Frequently, probes of airline crashes that occur outside the U.S. in which American investigators play a role prompt friction and outright disagreements between U.S. government and industry experts and local investigators leading the probes.
In the case of Ethiopia, the tension is exacerbated by the country’s limited staff and experience investigating major airliner crashes, according to industry and safety experts tracking the probe.
Officials in Addis Ababa, for their part, are still smarting from the results of an investigation into the deadly 2010 crash of an Ethiopian Airlines plane shortly after takeoff from Beirut. That probe, led by Lebanese authorities, found that the airline’s pilots failed to respond adequately to stormy weather during the aircraft’s ascent. Ethiopia at the time disagreed with the findings of the investigation, attributing the crash to bad weather.
“With this investigation, we are the ones who are in charge,” the chief of Ethiopia’s civil aviation authority, Col. Wosenyeleh Hunegnaw, said in a March 20 interview.
Another potential point of friction, according to some people familiar with the details, is the role played by experts from state-owned Ethiopian Airlines, which also faces scrutiny in the probe. The airline’s engineers have been providing technical support to officials from Ethiopia’s transport ministry.
Last edited by sansmoteur; 1st Apr 2019 at 12:35. Reason: Clean up non-article junk
There's national pride and reputations at stake here, and I don't mean in the US. Boeing are big enough to take whatever's coming on the chin an deal with it. Are Ethiopian/Ethiopian government?
As ever the two accidents will almost certainly come down to a relatively benign aircraft failure getting out of hand due to faulty human factors.
How did the ET pilots fail to recognise a failure that must heve been just about the sole topic of conversation in the crew room for the previous few weeks, analysed and discussed to death by everyone on the fleet? One that Boeing had published to all MAX operators with extreme urgency?`
What action did the ET training department take over it?
Surely that advice was passed on to the line pilots? If so how can it not have taken root? ...or was it?
Was the crew experience-mix even remotely suitable? Was it compatible with published company policy?
The facts from the recorders must have been known to and publishable by the authorities for a couple of weeks now - this delay is beginning to look like unwillingness to publish, not inabiity.
At this stage one can only surmise the whys and wherefores, but chances are there's stuff in there that the publisher either doesn't want publishing or hasn't included when the other interested parties believe it should be.
And that ain't good for the whole point of flight safety.
Ethiopia would do well to ensure total transparency here to reassure the rest of the world that they posess a responsible safety culture. Failure to do so will far outweigh any temporary saving of face if they do otherwise.
Sadly, having spent some time in the country I'm not holding my breath that face-saving won't turn out to be the order of the day, and some 'in charge' Colonel telling us they'll do it their way is hardly reassuring.
As ever the two accidents will almost certainly come down to a relatively benign aircraft failure getting out of hand due to faulty human factors.
How did the ET pilots fail to recognise a failure that must heve been just about the sole topic of conversation in the crew room for the previous few weeks, analysed and discussed to death by everyone on the fleet? One that Boeing had published to all MAX operators with extreme urgency?`
What action did the ET training department take over it?
Surely that advice was passed on to the line pilots? If so how can it not have taken root? ...or was it?
Was the crew experience-mix even remotely suitable? Was it compatible with published company policy?
The facts from the recorders must have been known to and publishable by the authorities for a couple of weeks now - this delay is beginning to look like unwillingness to publish, not inabiity.
At this stage one can only surmise the whys and wherefores, but chances are there's stuff in there that the publisher either doesn't want publishing or hasn't included when the other interested parties believe it should be.
And that ain't good for the whole point of flight safety.
Ethiopia would do well to ensure total transparency here to reassure the rest of the world that they posess a responsible safety culture. Failure to do so will far outweigh any temporary saving of face if they do otherwise.
Sadly, having spent some time in the country I'm not holding my breath that face-saving won't turn out to be the order of the day, and some 'in charge' Colonel telling us they'll do it their way is hardly reassuring.
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What I don't understand (well I do because building airplanes is all about keeping the costs down) is why they keep using these "obsolete" and fragile vane sensors.
Back in 1979 when we first got the F-16's we where all too happy to see "new" differential pressure activated AOA sensors. => But => But => And that is where it all goes dark => They are more expensive.
Back in 1979 when we first got the F-16's we where all too happy to see "new" differential pressure activated AOA sensors. => But => But => And that is where it all goes dark => They are more expensive.
Differential pressure sensors are bitches, even more than pitot tubes and static pressure ports. After all you have two tubes which can get congested by a lot of things.
The vane however is an extreme simplistic design. If it can be turned on the ground and if heating is present nothing should go wrong there.
So my odds are on the wiring harness as well.
Timing conditions within the Software have also been mentioned. From my profesionnal experience I would rule that out as well, as such systems monitor their execution times constantly and will declare themselfes faulty if problems are detected in this domain.
Regards
B
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STS/MCAS NG/MAX
Now that the MCAS is being classified as a subsystem of the STS wouldn't the below paragraph - possibly without the EFS module part - read like something you'd find in a Boeing MAX AFM if the intent were to give a brief non-technical description of MCAS?
"As airspeed decreases towards stall speed, the speed trim system trims the stabilzer nose down and enables trim above stickshaker AOA. With this trim schedule the pilot must pull more aft column to stall the airplane. With the column aft, the amount of column force increase with the onset of EFS module is more pronounced."
This paragraph has been in my B737NG manual for atleast 12 years but I'm not sure if that particular fact is what would have made me take action if my nose were being trimmed down in an inappropriate manner.
"As airspeed decreases towards stall speed, the speed trim system trims the stabilzer nose down and enables trim above stickshaker AOA. With this trim schedule the pilot must pull more aft column to stall the airplane. With the column aft, the amount of column force increase with the onset of EFS module is more pronounced."
This paragraph has been in my B737NG manual for atleast 12 years but I'm not sure if that particular fact is what would have made me take action if my nose were being trimmed down in an inappropriate manner.
Last edited by TTail; 1st Apr 2019 at 13:07. Reason: typo
U.S., Ethiopian Investigators Tussle Over 737 MAX Crash Probe
Tension over access to and interpretation of data comes ahead of a preliminary report on what happened to the Boeing plane
Tension is simmering between U.S. and Ethiopian officials as investigators prepare to release in the coming days an interim report about the Boeing Co. 737 MAX jetliner that nose-dived after takeoff from Addis Ababa on March 10, according to people from both countries.
U.S. investigators, according to people familiar with their thinking, have privately complained that Ethiopian authorities have been slow to provide data retrieved from the black-box recorders of Ethiopian Airlines Flight 302, which went down minutes into a flight to Nairobi, killing all 157 people on board.
American air-safety officials also have described what they view as an aloof attitude among the Ethiopians toward other investigators and say the Ethiopians have provided often limited access to relevant crash information, these people said.
A spokesman for the Ethiopian transport minister didn’t respond to requests for comment Sunday. Ethiopians involved in the probe, for their part, have chafed at what they see as American efforts to exert control over the preliminary report, according to other people familiar with the investigation.
The behind-the-scenes maneuvering, according to people from both countries, has impeded but not prevented the international investigators from working together.
The preliminary crash report, according to people briefed on the details, is expected to say that data analyzed so far indicates the Ethiopian accident bears important similarities to the crash of a Lion Air 737 MAX plane that went down in Indonesia less than five months earlier, including activation of an automated stall-prevention system and related features.
Boeing is in the process of rolling out a software fix and enhanced training related to the automated feature, called MCAS.
Publicly, U.S. officials have expressed satisfaction with the sharing of information. Last Wednesday, Robert Sumwalt, chairman of the National Transportation Safety Board, which is leading U.S. participation in the probe, told a Senate subcommittee his experts have gotten the data they need.
On Sunday, a Boeing spokesman said: “We have great respect for the Ethiopian government. As a party to the investigation, we’re following all international protocols and conduct all our work through” the U.S. safety board.
From the outset, though, Ethiopian officials have kept tight control of the probe, carefully guarding the recorder data and pushing back at what they view as efforts by Boeing investigators to influence and speed up release of the preliminary report on the crash, according to people familiar with the matter.
The Boeing spokesman said it was “absolutely not true” that the company’s investigators are trying to influence or speed up the preliminary report.
Safety experts have also tussled over the interpretation of certain data and their presentation in the report, according to people from both countries.
Ethiopian officials asked the French aviation accident investigation bureau BEA, which downloaded data from the black boxes, to permanently delete that information from its servers once it had been transmitted to Ethiopian authorities. The BEA has confirmed complying with the request.
Frequently, probes of airline crashes that occur outside the U.S. in which American investigators play a role prompt friction and outright disagreements between U.S. government and industry experts and local investigators leading the probes.
In the case of Ethiopia, the tension is exacerbated by the country’s limited staff and experience investigating major airliner crashes, according to industry and safety experts tracking the probe.
Officials in Addis Ababa, for their part, are still smarting from the results of an investigation into the deadly 2010 crash of an Ethiopian Airlines plane shortly after takeoff from Beirut. That probe, led by Lebanese authorities, found that the airline’s pilots failed to respond adequately to stormy weather during the aircraft’s ascent. Ethiopia at the time disagreed with the findings of the investigation, attributing the crash to bad weather.
“With this investigation, we are the ones who are in charge,” the chief of Ethiopia’s civil aviation authority, Col. Wosenyeleh Hunegnaw, said in a March 20 interview.
Another potential point of friction, according to some people familiar with the details, is the role played by experts from state-owned Ethiopian Airlines, which also faces scrutiny in the probe. The airline’s engineers have been providing technical support to officials from Ethiopia’s transport ministry.
Tension over access to and interpretation of data comes ahead of a preliminary report on what happened to the Boeing plane
Tension is simmering between U.S. and Ethiopian officials as investigators prepare to release in the coming days an interim report about the Boeing Co. 737 MAX jetliner that nose-dived after takeoff from Addis Ababa on March 10, according to people from both countries.
U.S. investigators, according to people familiar with their thinking, have privately complained that Ethiopian authorities have been slow to provide data retrieved from the black-box recorders of Ethiopian Airlines Flight 302, which went down minutes into a flight to Nairobi, killing all 157 people on board.
American air-safety officials also have described what they view as an aloof attitude among the Ethiopians toward other investigators and say the Ethiopians have provided often limited access to relevant crash information, these people said.
A spokesman for the Ethiopian transport minister didn’t respond to requests for comment Sunday. Ethiopians involved in the probe, for their part, have chafed at what they see as American efforts to exert control over the preliminary report, according to other people familiar with the investigation.
The behind-the-scenes maneuvering, according to people from both countries, has impeded but not prevented the international investigators from working together.
The preliminary crash report, according to people briefed on the details, is expected to say that data analyzed so far indicates the Ethiopian accident bears important similarities to the crash of a Lion Air 737 MAX plane that went down in Indonesia less than five months earlier, including activation of an automated stall-prevention system and related features.
Boeing is in the process of rolling out a software fix and enhanced training related to the automated feature, called MCAS.
Publicly, U.S. officials have expressed satisfaction with the sharing of information. Last Wednesday, Robert Sumwalt, chairman of the National Transportation Safety Board, which is leading U.S. participation in the probe, told a Senate subcommittee his experts have gotten the data they need.
On Sunday, a Boeing spokesman said: “We have great respect for the Ethiopian government. As a party to the investigation, we’re following all international protocols and conduct all our work through” the U.S. safety board.
From the outset, though, Ethiopian officials have kept tight control of the probe, carefully guarding the recorder data and pushing back at what they view as efforts by Boeing investigators to influence and speed up release of the preliminary report on the crash, according to people familiar with the matter.
The Boeing spokesman said it was “absolutely not true” that the company’s investigators are trying to influence or speed up the preliminary report.
Safety experts have also tussled over the interpretation of certain data and their presentation in the report, according to people from both countries.
Ethiopian officials asked the French aviation accident investigation bureau BEA, which downloaded data from the black boxes, to permanently delete that information from its servers once it had been transmitted to Ethiopian authorities. The BEA has confirmed complying with the request.
Frequently, probes of airline crashes that occur outside the U.S. in which American investigators play a role prompt friction and outright disagreements between U.S. government and industry experts and local investigators leading the probes.
In the case of Ethiopia, the tension is exacerbated by the country’s limited staff and experience investigating major airliner crashes, according to industry and safety experts tracking the probe.
Officials in Addis Ababa, for their part, are still smarting from the results of an investigation into the deadly 2010 crash of an Ethiopian Airlines plane shortly after takeoff from Beirut. That probe, led by Lebanese authorities, found that the airline’s pilots failed to respond adequately to stormy weather during the aircraft’s ascent. Ethiopia at the time disagreed with the findings of the investigation, attributing the crash to bad weather.
“With this investigation, we are the ones who are in charge,” the chief of Ethiopia’s civil aviation authority, Col. Wosenyeleh Hunegnaw, said in a March 20 interview.
Another potential point of friction, according to some people familiar with the details, is the role played by experts from state-owned Ethiopian Airlines, which also faces scrutiny in the probe. The airline’s engineers have been providing technical support to officials from Ethiopia’s transport ministry.
My take on this posturing is they are trying to align holes in pieces of cheese that at best marginally overlap.
It's not that hard once you have the CVR and FDR. The trim behavior of Lion Air was pretty obvious and it would be very simple if it were the same in the case of ET302.
In many ways this aligns with Boeing moving forward with the 'MCAS fix', despite the (public) status of ET302 being indeterminate.
- GY
Join Date: Jan 2008
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Now that the MCAS is being classified as a subsystem of the STS wouldn't the below paragraph - possibly without the EFS module part - read like something you'd find in a Boeing MAX AFM if the intent were to give a brief non-technical description of MCAS?
"As airspeed decreases towards stall speed, the speed trim system trims the stabilzer nose down and enables trim above stickshaker AOA. With this trim schedule the pilot must pull more aft column to stall the airplane. With the column aft, the amount of column force increase with the onset of EFS module is more pronounced."
This paragraph has been in my B737NG manual for atleast 12 years but I'm not sure if that particular fact is what would have made me take action if my nose were being trimmed down in an inappropriate manner.
"As airspeed decreases towards stall speed, the speed trim system trims the stabilzer nose down and enables trim above stickshaker AOA. With this trim schedule the pilot must pull more aft column to stall the airplane. With the column aft, the amount of column force increase with the onset of EFS module is more pronounced."
This paragraph has been in my B737NG manual for atleast 12 years but I'm not sure if that particular fact is what would have made me take action if my nose were being trimmed down in an inappropriate manner.