Ethiopian airliner down in Africa
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Some detail lacking here. The master FCC is set by crew, normally to the side of the PF, initially by selecting the onside FD on first. Selecting the opposite autopilot flips the master to that side (I.e. if left seat is flying, but engages AP B, right side FCC becomes master). The nominated master FCC is annunciated on the MCP and is obvious to crew.
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What's the risk assessment?
Sorry to intrude here, just a passenger, but I'm baffled what risk assessment in a safety critical industry means that an aircraft that is already airborne needs to find a destination other than the one it was planning to go to in the UK?
I appreciate the fact that the type is effectively prohibited from UK/European airspace but surely asking the crew to go hawking around the world looking for a diversion is introducing additional risk to the baseline risk now associated with this aircraft rather than reducing it. It's got to land somewhere right? And even if it's going to go wrong it's better it goes wrong with every potential advantage in the crew's favour even if that's only ATC in English and familiar with the terrain at a familiar airport. As opposed to an unfamiliar airport with altitude / temperature that might even predispose to the failure condition being encountered after wandering round introducing additional constraints such as fuel.
I apologise if that risk assessment was done today on the basis of the weather in the UK being a risk - but I can't see it.
I work in a safety critical business; medical devices. If I know there's a safety advisory on a piece of kit then I'll risk assess the likelihood/impact of keeping it in service vs the benefit to the patient. That's a very different conversation when the operation's not started (on the ground) vs patient "on the table" (aircraft airborne). And sometimes we might be "brave" when the patient really needs it.
Just askin'
I appreciate the fact that the type is effectively prohibited from UK/European airspace but surely asking the crew to go hawking around the world looking for a diversion is introducing additional risk to the baseline risk now associated with this aircraft rather than reducing it. It's got to land somewhere right? And even if it's going to go wrong it's better it goes wrong with every potential advantage in the crew's favour even if that's only ATC in English and familiar with the terrain at a familiar airport. As opposed to an unfamiliar airport with altitude / temperature that might even predispose to the failure condition being encountered after wandering round introducing additional constraints such as fuel.
I apologise if that risk assessment was done today on the basis of the weather in the UK being a risk - but I can't see it.
I work in a safety critical business; medical devices. If I know there's a safety advisory on a piece of kit then I'll risk assess the likelihood/impact of keeping it in service vs the benefit to the patient. That's a very different conversation when the operation's not started (on the ground) vs patient "on the table" (aircraft airborne). And sometimes we might be "brave" when the patient really needs it.
Just askin'
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There is a cert requirement that as AOA increases, the nose up pilot command required must not decrease. This is demonstrated at fixed thrust levels so there is no change in thrust pitching moment. The 737MAX issue here that gives rise to the need for MCAS is that as AOA increases the lift provided by the engine cowling that is so large and mounted so far forward of the wing causes a nose up pitching moment that results is a decrease in the column pull needed to maintain a steady positive AOA rate. That characteristic is not compliant with the requirements. MCAS comes active during this maneuver putting in nose down stabilizer that must be countered by the column. The net effect of engine cowling lift and MCAS nose down stabilizer as AOA increases is that the column needed to complete the maneuver does not decrease part way through the range of AOA for which characteristics must be demonstrated. 737MAX without MCAS fails the cert demo. 737MAX with MCAS passes the cert demo.
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Sen. Ted Cruz (R-Texas), who leads a Senate subcommittee overseeing aviation, said in a statement Tuesday that U.S. authorities should ground the planes.
"Further investigation may reveal that mechanical issues were not the cause, but until that time, our first priority must be the safety of the flying public," Cruz said.
https://www.dallasnews.com/business/...ed-safety-flaw
"Further investigation may reveal that mechanical issues were not the cause, but until that time, our first priority must be the safety of the flying public," Cruz said.
https://www.dallasnews.com/business/...ed-safety-flaw
Does anyone know if the EASA notice is based on some new input (presumably from early readout of Ethiopian FDR) ?
If not I think this is draconian and frankly unwarranted - they could at the very least allow en-route flights to operate normally as the issue - if there is actually one - is in the takeoff phase.
On a different topic can anyone explain how an automation system (regardless of brand/purpose), let alone on a modern airliner, can be certified with only one control source ?
If not I think this is draconian and frankly unwarranted - they could at the very least allow en-route flights to operate normally as the issue - if there is actually one - is in the takeoff phase.
On a different topic can anyone explain how an automation system (regardless of brand/purpose), let alone on a modern airliner, can be certified with only one control source ?
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Just thinking ... not judging, just wondering... so nice to be naive sometimes...
Historically Boeing has always been quite clear and open about serious issues.
And thereby one, certainly not the only, of the companies and organizations that has made aerospace as safe as it is.
That reputation certainly got dented recently during the 787 program. Some are happy with it now, others still have professional reservations.
The Lion Air case caused other dents. The suggestion is that Boeing has been withholding information. They certainly have not been open.
Boeing did not open up about the design philosophy of MCAS, the design itself, the way in which it was tested, and certified, and documented and trained, etcetera.
This Ethiopian case magnifies this unusual lack of openness.
Simply said modern certification (not only in aerospace) puts a lot of proof and testing on the desk of the manufacturer rather than on the desk of the certification authority.
You wonder what was written and agreed about what kind of 'publication obligation of the certification process and results' this shift has caused.
To this day informed people know little of MCAS. Certainly not enough for peace of mind.
So what could Boeing do to start limiting the damage that is being done and still increasing rapidly. So rapid that it may dent the industry.
What would personally appeal to me is the chief engineer of the program giving an explanation about MCAS in general. So a very competent technical person with 'signature responsibility', don't think anyone else would do anymore.
This does not disrupt the Ethiopian investigation because we don't know if MCAS is even involved. So there would be no excuse not doing it citing this one, or for that matter even the Lion investigation. It is just basic historic knowledge and intent you might say.
You get the feeling that if they don't volunteer this now that at some stage they will be ordered to do this and add a number of other people and disciplines.
Chicago has a problem.
Historically Boeing has always been quite clear and open about serious issues.
And thereby one, certainly not the only, of the companies and organizations that has made aerospace as safe as it is.
That reputation certainly got dented recently during the 787 program. Some are happy with it now, others still have professional reservations.
The Lion Air case caused other dents. The suggestion is that Boeing has been withholding information. They certainly have not been open.
Boeing did not open up about the design philosophy of MCAS, the design itself, the way in which it was tested, and certified, and documented and trained, etcetera.
This Ethiopian case magnifies this unusual lack of openness.
Simply said modern certification (not only in aerospace) puts a lot of proof and testing on the desk of the manufacturer rather than on the desk of the certification authority.
You wonder what was written and agreed about what kind of 'publication obligation of the certification process and results' this shift has caused.
To this day informed people know little of MCAS. Certainly not enough for peace of mind.
So what could Boeing do to start limiting the damage that is being done and still increasing rapidly. So rapid that it may dent the industry.
What would personally appeal to me is the chief engineer of the program giving an explanation about MCAS in general. So a very competent technical person with 'signature responsibility', don't think anyone else would do anymore.
This does not disrupt the Ethiopian investigation because we don't know if MCAS is even involved. So there would be no excuse not doing it citing this one, or for that matter even the Lion investigation. It is just basic historic knowledge and intent you might say.
You get the feeling that if they don't volunteer this now that at some stage they will be ordered to do this and add a number of other people and disciplines.
Chicago has a problem.
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Thrust Pitching Moment Basics
Pitching moment caused by engine thrust is a function of how much thrust and where the engine is mounted vertically with respect to the center of gravity. Thrust pitching moment is not a function of how far forward or aft the engine is located. With this in mind, the nose up thrust induced pitching moment generated by the 737MAX engine is not greater than that for a 737NG. In fact, it is probably less as the center line of the larger MAX engine is higher than the center line of the smaller NG engine given their respective attachment geometries.
Hopefully it is now clear that the pitching moment of concern with the 737MAX engines that gives rise to the need for MCAS is related to the aerodynamic impact of the engine cowling location and geometry, not the magnitude nor location of the thrust vector generated by those engines.
Hopefully it is now clear that the pitching moment of concern with the 737MAX engines that gives rise to the need for MCAS is related to the aerodynamic impact of the engine cowling location and geometry, not the magnitude nor location of the thrust vector generated by those engines.
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Airbubba, the "control column actuated trim cutout switches" are switches located in the control column that stop an electric trim movement when the control column requests an elevator deflection contradicting the trim movement. This is the immediate response to a stuck electric trim button before using the STAB TRIM MAIN ELECT cutout switch on the control stand.
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Airbubba, the "control column actuated trim cutout switches" are switches located in the control column that stop an electric trim movement when the control column requests an elevator deflection contradicting the trim movement. This is the immediate response to a stuck electric trim button before using the STAB TRIM MAIN ELECT cutout switch on the control stand.
Does anyone know if the EASA notice is based on some new input (presumably from early readout of Ethiopian FDR) ?
If not I think this is draconian and frankly unwarranted - they could at the very least allow en-route flights to operate normally as the issue - if there is actually one - is in the takeoff phase.
If not I think this is draconian and frankly unwarranted - they could at the very least allow en-route flights to operate normally as the issue - if there is actually one - is in the takeoff phase.
It seems the issue is not so much with MCAS as with the engine location relative to the wing.
MCAS reads like a half baked solution to a problem that should not be there in the first place.
If so, this is not the kind of design philosophy I associate with Boeing.
Diverting aircraft in the cruise because they have a problem taking off doesn’t sound like a terribly rational response either.
MCAS reads like a half baked solution to a problem that should not be there in the first place.
If so, this is not the kind of design philosophy I associate with Boeing.
Diverting aircraft in the cruise because they have a problem taking off doesn’t sound like a terribly rational response either.
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(I understand that it's the AUTOPILOT Cutout switch that does the job).
But I am not a B737 pilot, so I am happy to stand corrected.
