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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 13th Mar 2019, 07:32
  #941 (permalink)  
 
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Originally Posted by hans brinker View Post
..... If you have stretched your plane so far you need an extra telescoping landing gear and higher speeds to prevent a tailstrike, and software trimming because of inherent instability you are doing something wrong.

Well, while not exactly the same, I guess you think they better dump the 777-300ER as well due to the design features needed on that jet??
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Old 13th Mar 2019, 07:35
  #942 (permalink)  
 
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Originally Posted by RatherBeFlying View Post
By the time a MAX 8 or 9 has made it to cruise, the phase of flight that claimed Lion and ET is long past. And the pax have to land somewhere, preferably within reasonable reach of destination.
MCAS event could happen at any phase of flight. You just need: a failed AoA sensor, AP disengaged (would failed AoA disengage AP?) and flaps up.
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Old 13th Mar 2019, 07:37
  #943 (permalink)  
 
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Tacoma Sailor....How does the data above fit with the theory of MCAS forcing a rapid descent?
ADSB data is not always accurate.
This data may not fit any theory yet, but there is fairly solid evidence of a rapid descent.
There is a large crater with small bits of 737Max in it.
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Old 13th Mar 2019, 07:39
  #944 (permalink)  
 
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Originally Posted by 12A View Post
Tell that to Porsche with their 911
And that, ladies and gentlemen, is complete bullshit. Porsche only built the 911 from 1963 until 1989. The model that is sold today under the marketing designation 911 has zero commonality (other than styling and marketing) with the actual model 911, very much unlike the 737 MAX.
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Old 13th Mar 2019, 07:40
  #945 (permalink)  
 
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Originally Posted by fox niner View Post
With all these airlines and governments around the globe grounding their MAX fleets,,,,,,,,......And can they be read out with some priority? The world demands some reassurance.
You think ....?
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Old 13th Mar 2019, 07:43
  #946 (permalink)  
 
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Time frame for CVR and data recorder analysis

I am a non professional, so grateful for any insight regarding recorder analysis. If the recorders are in a reasonable condition, I presume down loading data is like down loading from a massive USB stick. This surely must have already be done by now? As it seems that the cockpit crew were able to communicate with the tower, so there must have also been some crucial conversation between captain and first officer as well. That voice recording could quite quickly tell us what they thought was going on. What I am really asking i suppose, is how quickly, are we likely to hear a preliminary report of what happened to aircraft. For an example, if there was a terrorist saying, " i will blow up this plane", surely Boeing would release this information ASAP. However, if the voice clearly points to a stall system fault, would they be as quick to release their preliminary findings ?
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Old 13th Mar 2019, 07:56
  #947 (permalink)  
 
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Originally Posted by greenfields View Post
Well, while not exactly the same, I guess you think they better dump the 777-300ER as well due to the design features needed on that jet??
I don't know, what are those features?
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Old 13th Mar 2019, 08:14
  #948 (permalink)  
 
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AoA Sensor

So the AoA Sensor is usually a pretty rugged piece of kit.
What could cause it to fail?
Either the output has an anomaly (electrical/electronic side) or there is a mechanical problem (vane stuck).
What could cause a vane to stick?
Fine sand? Volcanic ash?
Where did this happen?
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Old 13th Mar 2019, 08:23
  #949 (permalink)  
 
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Originally Posted by Realbabilu View Post


at least those pilots who saved the previous pk-lqp Dps-cgk lion air won against Mcas accident, without knowing Mcas even existed and stick shaker blaring all along flight.
as a pax, are these pilots that could handle this situation are rare or not ?
if not then Boeing should really re examined their mcas, and aoa parts should be on MEL.
But could whole AOA system tested on ground ?
No not rare. Probably just every day bloke/ttes.
The cheese happened to line up for the crash crew; bad day, sub standard, no sleep, ex wife giving grief, fo thinking about his upcoming tinder date...
sometimes it just all comes together, sadly.
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Old 13th Mar 2019, 08:27
  #950 (permalink)  
 
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Originally Posted by KRUSTY 34 View Post


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?
I agree, but from the comments on this forum, the aircraft is not capable of flying to normal parameters without MCAS. I.e. the trim adjustment required as AOA increases due to the engine cowling lift. Does that mean it should never have been certified in the first place? Itís not exactly inherently unstable like a fighter, but Boeing have used automation to counteract problems with the design.
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Old 13th Mar 2019, 08:31
  #951 (permalink)  
 
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Originally Posted by TacomaSailor View Post
59-seconds after beginning the takeoff roll - the plane was at 200-knots and had gained NO altitude above the runway (based on elevation at 105-knots). Is that possible?
The aircraft was approximately 125' AAL (7750' AMSL) at the 59 second point (05:38:59Z). See the profile I posted a couple of days ago, where the altitudes are drawn to scale.
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Old 13th Mar 2019, 08:33
  #952 (permalink)  
 
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FCeng84, thanks for the very useful aerodynamics lessons. Joining others, we may be jumping ahead somewhat in our assumptions about the Ethiopian and indeed Lion crash but I personally believe that having now turned-over the MCAS stone the issue must be addressed, regardless of it's (non) role in recent accidents. Some (random) questions/observations:

Before the pilot world knew about MCAS, how would an MCAS failure have been manifested? Should it have been an 'MEL' Item? In other words, if it was not visible/known to pilots, how would anyone have known the system was working? Consequently, was it just looked upon as a sticking plaster necessary to get over a certification requirement and something that didn't need to be monitored or even in place for real world operations? I'm reminded of VW diesel engines and emission tests.

What was the rationale behind only using a single data source to the MCAS?

I think it has already been addressed but, does the flight regime mean that MCAS will activate at/before/about the same time as the stick shaker?

How did Boeing come to the conclusion that a 5 second pause after pilot trim inputs was the MCAS reset period?

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Old 13th Mar 2019, 08:34
  #953 (permalink)  
 
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Sorry for the thread drift, but as it is mentioned very often in this thread for obvious reasons and I can't find the original thread, can I ask - was the cause of the Lion Air crash actually determined or are definitive answers still awaited? Apologies again.
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Old 13th Mar 2019, 08:34
  #954 (permalink)  
 
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Last night's Rachel Maddow show on MSNBC quoted reports on the Aviation Safety Reporting System, with US pilots reporting uncommanded nose-down problems with the MAX just after take-off, solved by switching off AP.

It's been happening in the US too.

Edited to add: she reports that there was a five-week delay in implementing the software fix...because of Trump's government shutdown. Also, there's still an 'acting' head of the FAA, because that's yet another role that Trump hasn't filled. He wanted his personal pilot to get the job, but didn't get his way. The FAA seems to have issues.

"NEW: https://twitter.com/Boeing CEO Dennis Muilenburg spoke by phone with TRUMP this a.m., urging him not to ground 737 Max 8s after Sunday’s crash. * Muilenburg has tried to cultivate Trump. He visited Mar-a-Lago after AF1 dust-up, & Boeing donated $1M to Trump inaugural.'

Last edited by PaxBritannica; 13th Mar 2019 at 09:08.
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Old 13th Mar 2019, 08:39
  #955 (permalink)  
 
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Once bitten, twice shy... or NOT?


We pointed earlier ( post no 899 ) that Amsterdam and Lion Air accidents were in part due to single channel/sensor.

In fact on 31 July 2009, Boeing informed airlines about a future Service Bulletin that they are going to rectify the situation in regard to Amsterdam rad alt problem by a comparator function between the measured heights of the left and right radio altimeter systems.

https://books.google.com.tr/books?id...terdam&f=false

P.S. related page 130 bottom part.

Last edited by wetbehindear; 14th Mar 2019 at 05:32. Reason: wrong page number
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Old 13th Mar 2019, 08:53
  #956 (permalink)  
 
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Originally Posted by TacomaSailor View Post
11 seconds with 00' elevation gain (to 7,225') and acceleration from 105 to 154 knots
11 seconds with 25' elevation LOSS (to 7,200') and acceleration from 154 to 183 knots (did ETH-402 try to lift off runway and then settle back on to it?)
Bear in mind that ADS-B altitude granularity is 25ft, you won't see smaller increments than that. So it may only have dropped by a few feet but that is rounded to -25ft.

Also the altitude reported in ADS-B depends on the message type being parsed; some use the barometric pressure from the Mode-C source to calculate altitude per 1013hPa*, whereas others use the GNSS height corrected to WGS84. There's no AMSL data from ADS-B.

* aircraft at my local airport regularly land at -200ft per message type 7

Last edited by El Bunto; 13th Mar 2019 at 09:11.
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Old 13th Mar 2019, 09:14
  #957 (permalink)  
 
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Originally Posted by yellowtriumph View Post
Sorry for the thread drift, but as it is mentioned very often in this thread for obvious reasons and I can't find the original thread, can I ask - was the cause of the Lion Air crash actually determined or are definitive answers still awaited? Apologies again.

From the preliminairy report can be found that one of the AOA sensors gave a wrong reading leading to the aircraft trimming nose down, as well as a stickshaker and a multiple of fail flags related to speed and altitude.

Boeing also issued a bulletin where MCAS is blamed.

So there is no final report yet, but MCAS almost certainly was the root cause for the Lion Air crash.
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Old 13th Mar 2019, 09:16
  #958 (permalink)  
 
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Now those with long memories may recall another overstretched aircraft, the MD-11. That, too, got a "clever" bit of software to overcome design aspects. LSAS. Longitudinal Stability Augmentation System. Even the name sounds similar to MCAS. Did one of the onetime McDD engineers who stayed on after the Boeing takeover have anything to do with the more recent concept.

And again, those with long memories will recall that the MD-11 had a hull loss rate substantially out of kilter with norms, and was well known for ending up on its back and burned out alongside the runway on landing, exactly at the point where LSAS had been designed to kick in.

There were even discussions about it on PPRuNe at the time. One who seemed to understand its technicalities wrote "I seriously wonder if the FAA would be as accommodating now". Hmmm ...

Md-11 Lsas
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Old 13th Mar 2019, 09:21
  #959 (permalink)  
 
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Originally Posted by El Bunto View Post
Also the altitude reported in ADS-B depends on the message type being parsed; some use the barometric pressure from the Mode-C source to calculate altitude per 1013hPa*, whereas others use the GNSS height corrected to WGS84. There's no AMSL data from ADS-B.
Yes, although AFAIK the altitudes on FR24 always come from Airborne Position messages, which in turn always contain baro alt.

And of course if you know the QNH and altitude, as we do in this case, it's straightforward to apply the appropriate pressure correction to work out AMSL.
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Old 13th Mar 2019, 09:22
  #960 (permalink)  
 
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I think I remember forgetting this before... but as it appears that some of the problems with the 737 Max 8 seem to stem from overextending/overevolving an old-ish plane with short legs, why didn't Boeing develop the 757 instead. More modern plane, longer legs (taller u/c) etc?
Genuine question.
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