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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 12th Mar 2019, 04:30
  #581 (permalink)  
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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.".

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Old 12th Mar 2019, 04:39
  #582 (permalink)  
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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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Old 12th Mar 2019, 04:54
  #583 (permalink)  
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Captain was Pilot Flying. Addis is a "Capt only" Airport
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Old 12th Mar 2019, 05:03
  #584 (permalink)  
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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.
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Old 12th Mar 2019, 05:04
  #585 (permalink)  
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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?
If you stayed at low level and didn't pull the power WAY back (eg if you didn't know what speed you were doing) you'd very quickly (less than 6 minutes) be going VERY VERY fast.

Done a low-level level-off recently?
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Old 12th Mar 2019, 05:12
  #586 (permalink)  
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Originally Posted by MD80767 Driver View Post
Captain was Pilot Flying. Addis is a "Capt only" Airport
are you ET. Crew?
ADD is certainly NOT Cat C or Captain Only in most companies.
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Old 12th Mar 2019, 05:32
  #587 (permalink)  
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Originally Posted by oldoberon View Post
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

Is this correct? Can someone cite the source?
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Old 12th Mar 2019, 05:39
  #588 (permalink)  
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What is the source for the above statement? There is no information in the current B738M AOM that tells crews that the "MCAS cycles between the left AoA and the right AoA sensor".
I **suspect** ther confusion comes from a much earlier post- probably re lion/maintenance comments that as I ***vaguely *** recall - there is an automatic change/switch of right side to left side computer systems/ TO displays every flight cycle or similar.
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Old 12th Mar 2019, 05:43
  #589 (permalink)  
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Originally Posted by Cows getting bigger View Post
Some rough working assumptions (probably overly optimistic):

350 aircraft
In service for 2 years, each aircraft available 340 days/yr, 5 sectors/day.
Total number of departures: approx 1.2m giving a fatal accident rate of 1.67 per million flights.

In comparison using figures up to 2017:

Banderantie - 3.07. (Ouch!)
Concorde - 11.36 (indicative of very low numbers in service and utilisation)
F28 - 1.65
A310 - 1.34
B747 (early models) 1.02
B747 (-400 onwards) - 0.06
B737 (all models) - 0.28
A320 series - 0.11
First 737 max was delivered in May 2017 so none have been in operation for 2 years. Most have been in operation for less than 1 year. 5 sectors per day is also a very high estimate.

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Old 12th Mar 2019, 06:06
  #590 (permalink)  
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Originally Posted by MD80767 Driver View Post
Captain was Pilot Flying. Addis is a "Capt only" Airport
Not necessarily. In FlyDubai I seem to recall that it was, but in other airlines that I've been in it was not. It depends upon the airline and how they choose to categorise it.
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Old 12th Mar 2019, 06:09
  #591 (permalink)  
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Originally Posted by PlatinumFlyer View Post
I profoundly hope and pray this doesn't come back to bite them
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Old 12th Mar 2019, 06:16
  #592 (permalink)  
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Originally Posted by Dee Vee View Post


Just wow... Begs the question, how long have they known about the issues???
Was the aircraft pushed out too early to "meet schedule" and increase profit?
Sick of hearing the “safety come first” quote. How many accidents have been caused by trying to save money? Do they think people are stupid?
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Old 12th Mar 2019, 06:17
  #593 (permalink)  
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Originally Posted by PJ2 View Post
Is this correct? Can someone cite the source?
This is correct. MCAS is implemented within the two Flight Control Computers (FCCs). The Left FCC uses the Left AOA sensor for MCAS and the Right FCC uses the Right AOA sensor for MCAS. Only one FCC operates at a time to provide MCAS commands. With electrical power to the FCCs maintained, the unit that provides MCAS changes between flights. In this manner, the AOA sensor that is used for MCAS changes with each flight.
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Old 12th Mar 2019, 06:25
  #594 (permalink)  
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Thanks very kindly, FCeng84.

The switching from left to right to left etc., would likely be handled by the air-ground condition, I suspect?
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Old 12th Mar 2019, 06:28
  #595 (permalink)  
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This still will not prevent an urgent or quick movement of the switches to the OFF position if necessary.
From B707's, B727 & B747 all the same where in the event of a runaway stabilizer (or serious Nose Up\Down Stab trimming) the procedure was/is to switch the Stab Trim off and revert to Manual trim.
Instilled into me when flying these types and exercises practiced in simulator form time to time.

Would have thought this would have summed all up and provided operations Departments and Pilots with fairly clear instructions?

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Old 12th Mar 2019, 06:43
  #596 (permalink)  
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Originally Posted by c53204 View Post

Sick of hearing the “safety come first” quote. How many accidents have been caused by trying to save money? Do they think people are stupid?

Well aren't they? They'll go with the dodgiest of airlines to save $50! So the answer is, yes, people are stupid so maybe they are thinking exactly that.

Originally Posted by RatherBeFlying View Post
We are all keenly interested in what the FDR and CVR will show from this second accident.

Either they will show:
  1. a similar scenario as Lion or
  2. something different.
Barring something out of control by the crew and manufacturer, neither outcome will reflect well on the MAX.
Really? Do we not understand that had the crew in the Lionair accident performed the Runaway Stabiliser NNC then the jet will have in all likelihood have landed safely, as it did when the previous crew followed procedure? The Boeing bulletin is emphasising a procedure that already exists and all 737 crew should be aware of.

IF it has occurred again, AND the crew haven't done the checklist, then we really should be looking at pilot training. However, despite conclusions that many are jumping to here, we should be awaiting the CVR and FDR outcome because this has the potential to be one of many scenarios.

Last edited by greenfields; 12th Mar 2019 at 07:02.
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Old 12th Mar 2019, 06:45
  #597 (permalink)  
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(Top right above) Quote: "Pilots are reminded that an erroneous AOA can cause some or all of the following indications and effects."

How calm would you need to be, and long would you need to sort out all of those?

So, not only erroneous AOA sensors can set off MCAS.
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Old 12th Mar 2019, 07:28
  #598 (permalink)  
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Originally Posted by Vessbot View Post
Really? I'll admit to being wrong, but can you give some examples? I've done a small bit of traveling around Western and Eastern Europe (France, England, Bulgaria), and I don't remember anything about the light switches, and I feel like it would stick out in my memory as a shocking adjustment had they been down=on.
FIL's house in Australia, where down = on. Light switches baffling, because house first built for Finnish sea-captain: Finland, up=on. But not ALWAYS baffling. Anyway, as already pointed out, this is an arbitrary convention: the point is to implement a convention consistently.
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Old 12th Mar 2019, 07:30
  #599 (permalink)  
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737 pilot here.

What concerns me, is that many people are saying “I’d just set Power and Pitch, I’d notice if the aircraft was trimming against me, and move the STAB TRIM CUTOUT switches” Which, following the Lion Air accident, was exactly what I was thinking.

However, if this accident also turns out to be MCAS related, do we need to explore the possibility that the MCAS operation in flight, combined with the possibility of Airspeed Unreliable, Stall Warning, Possible Windshear alerts, is much more violent and hard to control than we initially thought?

Two sets of pilots can’t deal with it- is my aircraft actually flyable under these conditions 1000ft above the ground?
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Old 12th Mar 2019, 07:33
  #600 (permalink)  
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Put another way, if you’ve got a problem why would you choose to stay so low? As someone else said, set power, pick an attitude, get away from the ground and take things from there.

The first question must be - why didn’t/couldn’t the crew do that? Sort of sums-up 600+ Forum posts.
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