Ethiopian airliner down in Africa
Correct, except the AOA disagree warning light is an optional extra on the 737 MAX, so not every 737 has it.
For example the Lion Air 737 MAX didn't have either of those options installed, so it would have been difficult for the crew to determine they had an AOA disagree situation or not.
For example the Lion Air 737 MAX didn't have either of those options installed, so it would have been difficult for the crew to determine they had an AOA disagree situation or not.
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They assume that's the case because that's how the similar speed trim and mach trim functions work, the functions are controlled by the active FCC, and the active FCC changes when the plane lands, and reverts to one the left side after a power cycle.
Yes. In the discussions of both crashes, it has been striking that there has been so much confusion and disagreement about the operation of MCAS, much of it on the part of transport-experienced professional aviators. And no matter how much relevant material I've read, or how often I've re-read it, some things still aren't clear. For instance, some descriptions of the "system" (software patch) suggest that it is necessary for the MAX to be in a high bank for it to be activated. That doesn't make sense and it doesn't seem to have been the case in the Lion Air or the ET crashes (if the ET incident was MCAS-related), but it pops up repeatedly in lists and graphics.
Common sense and basic principles of human engineering dictate that a system or application that creates this much uncertainty and confusion, even among experts in a discipline, is begging for redesign.
Common sense and basic principles of human engineering dictate that a system or application that creates this much uncertainty and confusion, even among experts in a discipline, is begging for redesign.
AoA sensor switch for MCAS
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Salute PJ2 !!
The alternating AoA sensor scheme was fully eplained in the 610 thread and apparently was defeated for the 610 flight leg due to disconnecting things and putting in new things. Don't have time now to give you a specific post, but it is all there or on the tech log companion.
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Salute PJ2 !!
The alternating AoA sensor scheme was fully eplained in the 610 thread and apparently was defeated for the 610 flight leg due to disconnecting things and putting in new things. Don't have time now to give you a specific post, but it is all there or on the tech log companion.
Gums sends...
To board the MAX, or not to board - That is the question
We are all keenly interested in what the FDR and CVR will show from this second accident.
Either they will show:
The 37 has enjoyed an extraordinary run of success since its inauguration, but the latest engineering efforts seem to have pushed an initially robust and exemplary design into fragile behavior .
Either they will show:
- a similar scenario as Lion or
- something different.
The 37 has enjoyed an extraordinary run of success since its inauguration, but the latest engineering efforts seem to have pushed an initially robust and exemplary design into fragile behavior .
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737 max fleet grounded by Gol in Brazil.
They use their Max fleet for direct flights from Brazil to Florida.... Routes suspended, though imagine that they will be frantically working out how to honour current schedule with a fuel stop added in either the north of Brazil or the Caribbean
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Gotta agree!
In great VMC conditions - as reported - even the very worst of pilots should surely be able to maintain some semblance of the old Straight and Level.
Seems inconceivable to me that even if this Max had the same airspeed/attitude problems as the last one that crashed, the pilots couldn't have controlled it?
Something else going gone here I suspect!
A bad start to 2019!
In great VMC conditions - as reported - even the very worst of pilots should surely be able to maintain some semblance of the old Straight and Level.
Seems inconceivable to me that even if this Max had the same airspeed/attitude problems as the last one that crashed, the pilots couldn't have controlled it?
Something else going gone here I suspect!
A bad start to 2019!
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Clearly the MCAS situation - even if this accident doesn't turn out to be rooted in MCAS - is a strong indicator.
Now, 60 years later, we seem to have turned 180 degrees in our thinking. As little as I understand MCAS, it is clear, at least to me, that it is a computer controlled solution to aerodynamic instability inherent in the design.
While computerized aerodynamic stabilization of inherently unstable new designs may be the trajectory of future, to apply it as a fix as we push 50 year old designs to new limits may prove to be a mistake.
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Without reading 500 odd posts, do we know who was PF? The experienced Captain or the inexperienced Co-PIlot? Steep expereince difference don't you think?
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Interesting details/analysis by a control guru which **may** help explanation of which sensor does what and how
https://www.satcom.guru/2018/11/737-...n-command.html
Obviously put together after LionAir . .
https://www.satcom.guru/2018/11/737-...n-command.html
Obviously put together after LionAir . .
Peter was Boeing avionics supervisor for 767 and 747-400 data link recording, data link reporting, and satellite communications. He was an FAA designated engineering representative (DER) for ACARS, satellite communications, DFDAU, DFDR, ACMS and printers. Peter was lead engineer for Thrust Management System (757, 767, 747-400), also supervisor for satellite communications for 777, and was manager of terminal-area projects (GLS, MLS, enhanced vision).
The crew reported problems with air speed indications. Does that invalidate the reported 383kt speed?
It does seem a high speed for less than 6 minutes after takeoff and at low altitude. Is it even credible?
It does seem a high speed for less than 6 minutes after takeoff and at low altitude. Is it even credible?
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Interesting piece from Slate:
"Boeing’s either going to have to come up with a very convincing fix for whatever caused these two crashes, or think about starting over with a fresh sheet of paper.".
https://slate.com/technology/2019/03...e-737-max.html
"Boeing’s either going to have to come up with a very convincing fix for whatever caused these two crashes, or think about starting over with a fresh sheet of paper.".
https://slate.com/technology/2019/03...e-737-max.html
Interesting yes, but if they can write this with a straight face... "Malaysia Airlines, which the public viewed with misgivings after it lost two 777s in less than five months in 2014. Though it bore no obvious responsibility for either incident—one was shot down by Russia, the second was hijacked..." how deep will the rest of it be?
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737 MAX stabilizer cutout switches are guarded. With the guards in their normal, closed positions the switches are forced into the position that provides normal operation of the stabilizer. To cutout the stabilizer motor (i.e., disable electric trim from any source) the guards must be raised and the switches moved to the position that is only possible with the guards raised. Guarded switches of this sort provide two very strong levels of safety. First they make it very difficult/impossible to toggle the switch inadvertently as the guard must be raised before the switch can be toggled. Second they make the polarity of the switch very clear as normal operation position is the only one possible with the guard closed.
Originally Posted by Etudiant
The crew reported problems with air speed indications. Does that invalidate the reported 383kt speed?
It does seem a high speed for less than 6 minutes after takeoff and at low altitude. Is it even credible?
It does seem a high speed for less than 6 minutes after takeoff and at low altitude. Is it even credible?
Done a low-level level-off recently?
lancs said " From the Lion Air thread, I believe MCAS cycles between the 2 AOAs between each flight..""..
If the system uses 1 &2 on alternate flights both are wired in, I would think it is relatively simple to put a 1-2 switch in the cockpit but it is only active when the red light / HUD shows there is a difference, that could possibly immediately allow crew to rectify problem
Oldoberon
If the system uses 1 &2 on alternate flights both are wired in, I would think it is relatively simple to put a 1-2 switch in the cockpit but it is only active when the red light / HUD shows there is a difference, that could possibly immediately allow crew to rectify problem
Oldoberon