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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 12th Mar 2019, 20:40
  #801 (permalink)  
 
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Just the one UK TUI MAX that didnt make it home , G-TUMF on extended leave down in Tenerife.
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Old 12th Mar 2019, 20:41
  #802 (permalink)  
 
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Originally Posted by MPN11 View Post
That post suggests that using the electric trim button (presumably the most convenient practice) generates issues. Whereas, after toggling the stab off, the geriatric trim wheel solves all problems?

Oh, and using primary flying controls instead of autopilot settings, I assume?
Using the electric trim buttons but not fully trimming the airplane to offload column force can lead to progressive net stabilizer motion in the airplane nose down direction as appears to be the case with the last 30 seconds of the Lion Air event. Using the electric trim buttons to fully retrim to zero column force (Lion Air event prior to last minute) supports continued controlled flight. Given the choice between the former and the latter, I choose the latter. Given the choice between the latter and shutting down all electric stabilizer control I would choose to manage the stabilizer via the manual trim wheel for the rest of this flight.

You are correct about not having autopilot once the stabilizer is cutout. Without electric stabilizer control from the autopilot stabilizer offload logic, autopilot functionality cannot be provided.
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Old 12th Mar 2019, 20:45
  #803 (permalink)  
 
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Originally Posted by FCeng84 View Post
1. First thing is pull the column to put in the between 5 to 8 degrees of airplane nose up elevator needed to offset the MCAS stabilizer increment.
2. Use manual pitch trim to re-establish trim to the point of not needing to hold column.
3. If stabilizer runs airplane nose down again, recognize it as inappropriate and arrest by using manual pitch trim to stop MCAS stabilizer motion and move stabilizer back to trimmed position. (No need to sit idly by and watch 10 seconds of stabilizer motion taking you away from trim go in when you have determined that is not appropriate.)
4. Call for PNF to toggle stabilizer cutout switches and discuss managing pitch trim via manual trim wheel for the balance of this flight.
5. Make sure that this event is squawked in a manner that assures:
- The source of the errant stabilizer motion is identified and corrected prior to the next flight
- The next crew to fly this bird knows full well what was encountered on this flight and what was done to work around it.
To play devil's advocate.

So on any occasion on climb after TO and this was to occur, this would be your modus operandi? Stick shaker or not? Low or erroneous ASI reading or not? Just pull against MCAS and tell PNF to start flicking switches? I know where you're coming from, but, unfortunately it's just not always as simple as the way you're portraying. At 1000ft you dont have much room to play with in the first place, which in itself adds pressure. Again, confirmation bias, people had commented earlier that "look out the window, you'll know if you're close to stall". Say for example this captain who had 8,000 hours of instruments reading correctly, the one time he gets put in a scary position he's meant to look out the window and say to his 200 hour FO "plane is wrong, at 1,000ft I can tell our speed is good". No, his confirmation bias will be, "we're about to stall, the readings must be right, what the f***??".
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Old 12th Mar 2019, 20:51
  #804 (permalink)  
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Originally Posted by LiamNCL View Post
Just the one UK TUI MAX that didnt make it home , G-TUMF on extended leave down in Tenerife.
And another TUI MAX was wildly circling Bologna just before the EASA cut off time at 1900z - seems to have difficulty finding someone to make a decision where to park the upcoming static display whilst en route from Egypt to Brussels

189 pax now have an Italian holiday extension FOC
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Old 12th Mar 2019, 20:53
  #805 (permalink)  
 
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Originally Posted by FCeng84 View Post
For large exceedence of the MCAS activation AOA threshold, MCAS will command 2.5 degrees of stabilizer at low Mach number but less than 1/3rd of that at cruise Mach number (gradual Mach number based schedule between).
So you are saying that if you AoA sensor goes bananas right after takeoff (and you have not bought the “option” to see AoA vane displayed), then as mcas activates, you start fighting it - and as you have no time to reduce thrust you develop speed of 380kts while 2000f AGL, mcas will happily apply 2.5 degrees, because you are, after all, at low mach speed?


Or... your flaps got stuck so you are landing with flaps 0, you are on short final, hit a bird directly into AoA, mcas repeatedly applies 2.5 degrees trim while you are a few hundred feet AGL, because clearly that is safe at low mach numbers?

What could possibly go wrong?
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Old 12th Mar 2019, 20:54
  #806 (permalink)  
 
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Originally Posted by FCeng84 View Post
While there is not yet sufficient information to draw a clear link between the ET accident that is the subject of this thread and MCAS I am deeply troubled by the amount of misinformation regarding MCAS that is being spread here. Reluctantly I offer the explanation below without any suggestion that this system contributed to the tragedy in Ethiopia this last weekend. The truth will be revealed by the recorder data and the full investigation. I strongly implore those who do not know MCAS details to stop providing incorrect information here or anywhere else. Posing questions is fine, but please do not state as fact that about which you are not sufficiently knowledgeable.

MCAS Operation Clarification

MCAS is triggered when all of the following are true:
A. Sensed AOA exceeds a flight condition based activation threshold
B. Flaps are fully retracted (i.e., up)
C. Autopilot is not engaged

When triggered, MCAS commands nose down stabilizer as a function of how much AOA has exceeded the activation threshold and the current Mach number. For large exceedence of the MCAS activation AOA threshold, MCAS will command 2.5 degrees of stabilizer at low Mach number but less than 1/3rd of that at cruise Mach number (gradual Mach number based schedule between). For a lesser exceedence of the MCAS activation AOA threshold the size of the stabilizer increment will be proportionally less. MCAS stabilizer command will be stopped immediately upon pilot activation of pitch trim. (Pilot trim input also serves as MCAS reset - see next paragraph.)

Once MCAS has commanded one increment of stabilizer motion, it will not command more until it has been reset. MCAS is reset if any of the following occur:
1. Pilot makes a manual trim command. (MCAS will not re-activate until there have been 5 continuous seconds without pilot trim command.)
2. AOA drops below MCAS activation threshold and MCAS has run stabilizer in the airplane nose up direction taking out the increment of airplane nose down command it inserted earlier.
3. Autopilot is engaged and then disengaged.

Without pilot trim input, MCAS will not run the stab more than one increment (up to 2.5 degrees) unless MCAS is reset via either 2 or 3 above.

Talk of MCAS running the stabilizer for 10 seconds, pausing for 5 seconds, and then running it again repeatedly without pilot trim input are patently incorrect.
Am in total agreement with above. However that which concerns me is " activation threshold ". How are these values set and what protections have been programmed into the software for errors and other failures, such as AoA malfunction and failure, A/P disengagement and flap/ slat retraction. What systems, oral and visual, are installed to alert crew of auto MCAS engagement. Perhaps those familiar with the system may enlighten us on this subject.
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Old 12th Mar 2019, 20:55
  #807 (permalink)  
 
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Originally Posted by LiamNCL View Post
Just the one UK TUI MAX that didnt make it home , G-TUMF on extended leave down in Tenerife.
It will likely position back to Luton shortly.
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Old 12th Mar 2019, 20:58
  #808 (permalink)  
 
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Originally Posted by silverstrata View Post
Actually, this 'talk' is perfectly correct. When the MCAS system is activated erroneously, the pilot will inevitably make a trim input. And if your trim input is insufficient to counter the MCAS input, as was the case on the Indonesian, you rapidly end up with full nose down trim.

And I have to ask again, because nobody has answered - why would anyone invent a system that gives full nose-down trim? It goes against all aviation history and procedures. Remember the old adage - NEVER FLY WITH THE TRIMMER. And yet here is Boeing effectively using the trimmer as a primary flight control - deliberately placing the aircraft out of trim, instead of keeping it in trim.

That is why all other aircraft have stick-pushers, so you fly the stall with the primary flight controls, not the trimmer. The difference? Assisting the stall with the trimmer leaves you out of trim for the subsequent dive - with 60 kg of pressure on the stick, and 60 turns of the trim before you get back to something that is flyable. Conversely, when a stick pusher relents, you are still in trim, and can recover and fly away with ease. So why did Boeing chose such an absurd system for the 737-Max? Are Boeing really penny-pinching to such a degree? They should have taken a leaf out of the British Midland book - quote: "if you think safety is expensive, try having an accident..."

Silver
Silver - Your comments above are all worthy of review and consideration. The 737 is not a fly-by-wire airplane and thus does not have an augmented elevator command when flying manually. Earlier models (pre-MAX) used electric stabilizer control to address speed stability (STS). This approach was expanded to address otherwise uncertifiable 737MAX Cm-alpha characteristics by driving the stabilizer through the MCAS function. MCAS underwent extensive analysis and testing prior to certification. An assumption that was made throughout was that if the crew did apply manual trim, they would not stop their manual trim inputs for 5 seconds or longer without having offloaded column forces to (or near) zero. As mentioned via earlier posts in this thread, modifications to MCAS have been developed and will be out to the fleet this spring to improve MCAS safety. One of the key factors is removing the assumption that the crew, having activated manual trim, will provide complete manual trim to zero column force.
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Old 12th Mar 2019, 20:59
  #809 (permalink)  
 
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Originally Posted by SLFinAZ View Post
The FO had an MPL not an ATPL, The program provides for 70 hours of actual flight time and 130 hours of simulator training. From an earlier post of a pilot who actually flew with ET he stated that most MPL holders had roughly 230 total hours before they were released to Line (vs. Training) captains.
Thank you.
Probably a discussion for "elsewhere", but MPL does seem to be a bit of a "short cut" affair.
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Old 12th Mar 2019, 21:03
  #810 (permalink)  
 
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Originally Posted by 22/04 View Post
The wide range of views on here is something I applaud - rather I am concerned by some people who do not live in the real world - this one here.

MPLs are a fact of life- I fly EasyJet and Ryanair and the FOs often look like they should still be at school. Same on SpiceJet and Go-Air in India. I don't see them going away. The US seems to be out of step if anything by still insisting on more experience- I am surprised commercial pressure hasn't led to the same there.

Aeroplanes must be built such that they can be flown by these crews - safely operated all over the world. As I said yesterday, I am not sure certification bodies are doing their duty here.
No.

It is time for the Regulators and Airlines to realise that flying a jet isn't the simple task that they keep trying to delude themselves into believing, in the name of cost cutting. Hopefully this is the accident that is the turning point in refocusing training and money spent on pilot training.

Last edited by greenfields; 12th Mar 2019 at 23:05.
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Old 12th Mar 2019, 21:03
  #811 (permalink)  
 
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Originally Posted by derjodel View Post


So you are saying that if you AoA sensor goes bananas right after takeoff (and you have not bought the “option” to see AoA vane displayed), then as mcas activates, you start fighting it - and as you have no time to reduce thrust you develop speed of 380kts while 2000f AGL, mcas will happily apply 2.5 degrees, because you are, after all, at low mach speed?


Or... your flaps got stuck so you are landing with flaps 0, you are on short final, hit a bird directly into AoA, mcas repeatedly applies 2.5 degrees trim while you are a few hundred feet AGL, because clearly that is safe at low mach numbers?

What could possibly go wrong?
Scary stuff. If this is the current state of affairs with Boeing's engineering department - as it apparently is - I will as a passenger avoid their recent creations as much as possible.
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Old 12th Mar 2019, 21:03
  #812 (permalink)  
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Originally Posted by DaveReidUK View Post
It will likely position back to Luton shortly.
Do you think so Dave?

EASA has stopped all MAX flying from 1900Z

One TUI MAX was circling Bologna at 1859z - ?? where to park the upcoming static display whilst en route with pax from Egypt to BRU ??
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Old 12th Mar 2019, 21:05
  #813 (permalink)  
 
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Political decission

It appears that air safety and airworthiness is a political decision in the end? When most of the western world has grounded the MAX, US is still arguing it's business as usual.
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Old 12th Mar 2019, 21:05
  #814 (permalink)  
 
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Originally Posted by rog747 View Post
Do you think so Dave?

EASA has stopped all MAX flying from 1900Z
Neither the CAA nor the EASA restrictions preclude a ferry/positioning flight back to base.
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Old 12th Mar 2019, 21:07
  #815 (permalink)  
 
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Originally Posted by FCeng84 View Post
1. First thing is pull the column to put in the between 5 to 8 degrees of airplane nose up elevator needed to offset the MCAS stabilizer increment.
2. Use manual pitch trim to re-establish trim to the point of not needing to hold column.
3. If stabilizer runs airplane nose down again, recognize it as inappropriate and arrest by using manual pitch trim to stop MCAS stabilizer motion and move stabilizer back to trimmed position. (No need to sit idly by and watch 10 seconds of stabilizer motion taking you away from trim go in when you have determined that is not appropriate.)
4. Call for PNF to toggle stabilizer cutout switches and discuss managing pitch trim via manual trim wheel for the balance of this flight.
5. Make sure that this event is squawked in a manner that assures:
- The source of the errant stabilizer motion is identified and corrected prior to the next flight
- The next crew to fly this bird knows full well what was encountered on this flight and what was done to work around it.
You may well believe it's that simple. There are plenty of distractions in the real world from ATC, terrain, weather/turbulence etc. That's before the stick shaker activates and the autopilot disconnects. Whilst you are trying to work out why that has happened (because it could be a variety of reasons) and fly the aircraft (including trimming), the aircraft is working against you. And this aircraft trims automatically on every departure, often against you.

Sat typing at a keyboard it appears obvious. All pilots will be able to tell you the memory items.
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Old 12th Mar 2019, 21:18
  #816 (permalink)  
 
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Pilot error

"Pilot induced oscillation" and "some pilots are not as well trained as pilots in US": https://video.foxnews.com/v/60130558...#sp=show-clips
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Old 12th Mar 2019, 21:20
  #817 (permalink)  
 
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IF (of course it's still a big IF) a faulty AOA sensor input is at fault again here feeding MCAS invalid AOA position, a person might want to look into the recent Quality assurance and manufacturing of those AOA probes. I would assume the Lion Air and ET Max's are not too far off of each other, which may have a similar batch of AOA probes.

I agree that the simple and appropriate fix to the system would be to have to see 2 valid AOA inputs for a stall or near stall position. It's hard to believe they would engineer such a critical system with only one AOA input required.
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Old 12th Mar 2019, 21:21
  #818 (permalink)  
 
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Originally Posted by procede View Post
Another AoA / stall recovery / horizontal stabilizer autotrim problem?
I worked for a national carrier in Africa for the better part of a decade. We sent our cadets all over the world for initial pilot training, type ratings recurrence etc. our initial batch of pilots were Air Force officers. Said country didn’t have any aircraft in their inventory...out of 4 sent for type rating training, only 1 made it. This wasn’t really their fault. They needed some additional training to successfully complete advanced jet training. We sent 12 an initio pilots to the US to a well known 141 academy in Florida. 1 pilot came back with a commercial certificate out of 12. We then sent a batch to S Afrika. These were successful for the most part as they were sent based on aptitude and not political connections. The last batch, we sent to Ethiopia for an initio. They were gone for nearly 2 years. Their graduation involved much pomp and ceremony. Many photos and vip’s were present. Many delegates came and even ministers and ambassadors attended this major milestone. Eyes rolling. All of these freshly graduated cadets then did type rating training in Ethiopia. This took another 4-6 months. We now had freshly minted, expert super pilots. None of them could fly a 737 and required over 6 months of line training before they were released to fly the line. 2 failed recurrent at a different facility with non Ethiopian instructors. Others were sent to a non Ethiopian facility to redo their types.
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Old 12th Mar 2019, 21:27
  #819 (permalink)  
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Originally Posted by DaveReidUK View Post
Neither the CAA nor the EASA restrictions preclude a ferry/positioning flight back to base.
I've not seen the EASA notice, but can you help me to understand how the CAA one permits a positioning flight? Does "must not be flown" (2.1a, 2.1b) mean something different to the interpretation I'm giving it?
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Old 12th Mar 2019, 21:32
  #820 (permalink)  
 
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Remember , stick pushers will only work if the elevators are big enough. The whole issue is that they're not. Hence the MCAS inputs a change to the angle of the whole tailplane. The whole back end should have had a redesign years ago, and also any critical AoA detectors should be triplicated (not just two).
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