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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 12th Mar 2019, 22:50
  #841 (permalink)  
 
Join Date: May 2011
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QS 4160 seems to have made up its mind to go somewhere..
Hopefully, somewhere with fuel! According to Planefinder, this aircraft has been airborne for something like 5 hours. It looks as if it may be heading for Tunis.
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Old 12th Mar 2019, 22:51
  #842 (permalink)  
 
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These two Smartwings are they hanging about long enough to declare a fuel emergency ?
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Old 12th Mar 2019, 22:51
  #843 (permalink)  
 
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Originally Posted by _pudknocker_ View Post
Control column actuated stabilizer trim cutout switches stop operation of the main electric and autopilot trim when the control column movement opposes trim direction. When the STAB TRIM override switch is positioned to OVERRIDE, electric trim can be used regardless of control column position.

I just grabbed that from the NG tech manual. Iím assuming that the MAX has them as well?
One big read button on the yoke that disables ALL automatic functions, including MCAS!

I donít fly the 737, but the regional airliner I have flown for the last 20 years gives total control to the pilot once this button is pushed. Not even the yaw damper is retained. I mean Jesus H Christ! What the hell has happened to simple common sense in design?
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Old 12th Mar 2019, 22:54
  #844 (permalink)  
 
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Grrr

Originally Posted by LiamNCL View Post
These two Smartwings are they hanging about long enough to declare a fuel emergency ?
The irony of some flights not being allowed into the airspace:

The minute they call a mayday they'll be given assistance and allowed in!

So, when it seems to be functioning fine they're told "Go away! You're not safe"
When they call a Mayday, "come on ahead into our country, we'll get some fire crew and ambulances"
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Old 12th Mar 2019, 23:00
  #845 (permalink)  
 
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QS1201 now headed back the way it came too.
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Old 12th Mar 2019, 23:05
  #846 (permalink)  
 
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The EASA ban appears only to work in parts. FlyDubai A6-FNC has departed Bucarest in the last couple of minutes.
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Old 12th Mar 2019, 23:09
  #847 (permalink)  
 
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Originally Posted by positiverate20 View Post
The irony of some flights not being allowed into the airspace:

The minute they call a mayday they'll be given assistance and allowed in!

So, when it seems to be functioning fine they're told "Go away! You're not safe"
When they call a Mayday, "come on ahead into our country, we'll get some fire crew and ambulances"
Seems ones off to Tunis and the other Ankara.
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Old 12th Mar 2019, 23:12
  #848 (permalink)  
 
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excuse my ignorance but surely wouldn't it have been more sensible for the authorities to give a cut-off time of say, midnight tonight, instead of blanket bans everywhere? two aircraft have now spent hours more in the air than they needed to, no doubt inducing panic amongst the pax, being held then told to go elsewhere. QS4160 now landing Tunis and it looks like QS1201 enroute to Ankara, having held over the Black Sea. Knee jerk reactions when they have no actual factual data?

Why not say all aircraft once landed at destination have to be grounded? There was a max into MAN earlier today, AFTER the announcement.
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Old 12th Mar 2019, 23:13
  #849 (permalink)  
 
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Originally Posted by LiamNCL View Post
Seems ones off to Tunis and the other Ankara.
there doesn't appear to be an issue with the landings, only the take off phase.
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Old 12th Mar 2019, 23:15
  #850 (permalink)  
 
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The aircraft holding at Malta seems to be landing in Tunisia.
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Old 12th Mar 2019, 23:16
  #851 (permalink)  
 
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Originally Posted by Rudder Sir View Post
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.
One detail that must not be overlooked is that the crew has control over which FCC is engaged to perform autopilot / flight director functions, but does not have control over which FCC provides STS and MCAS when flying manually. As stated in other posts, first power-on yields STS and MCAS from the left FCC. Each subsequent air-to-ground cycle without FCC electric power down and back up causes the FCC to be used for STS and MCAS to toggle between the two.
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Old 12th Mar 2019, 23:20
  #852 (permalink)  
 
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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'


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Old 12th Mar 2019, 23:23
  #853 (permalink)  
 
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Why did it take so long and 300+ pax and crew deaths for the industry to acknowledge that a 50 years old original design cannot be modified/updated/re-engineered endlessly?
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Old 12th Mar 2019, 23:26
  #854 (permalink)  
 
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Originally Posted by hans brinker View Post
You would be making things worse by adding power. To get out of a high AOA, you lower the nose before adding power.....
Hans - your patience is amazing. You are correct about the relationship between 737MAX engines and need for MCAS. It has nothing to do with the thrust pitching moment!!!

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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Old 12th Mar 2019, 23:27
  #855 (permalink)  
 
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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
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Old 12th Mar 2019, 23:33
  #856 (permalink)  
 
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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 ?
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Old 12th Mar 2019, 23:34
  #857 (permalink)  
 
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Originally Posted by KRUSTY 34 View Post
One big read [sic] button on the yoke that disables ALL automatic functions, including MCAS!
I don't believe this is true on the MAX from what I've read here.
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Old 12th Mar 2019, 23:38
  #858 (permalink)  
 
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Originally Posted by Luc Lion View Post
pudknocker,
I can't find back where it was, but I read somewhere that the control column actuated trim cutout switches were ineffective for stopping MCAS trim inputs.
Are there control column actuated trim cutout switches on this plane? Aren't the trim cutout switches on the center console above the number 2 fire handle?
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Old 12th Mar 2019, 23:42
  #859 (permalink)  
 
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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.
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Old 12th Mar 2019, 23:42
  #860 (permalink)  
 
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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.
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