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-   -   Ethiopian airliner down in Africa (https://www.pprune.org/rumours-news/619272-ethiopian-airliner-down-africa.html)

TowerDog 21st Mar 2019 03:11


​​ it all boils down to the basic fact that the system is there to “fix” poor aerodynamics. ​​​​​
No..The MCAS System was there to meet certification requirements.

Pilot DAR 21st Mar 2019 03:16


That doesn't suit pedantic test pilots, they want a smoothly increasing pull force all the way to the break.
It's not suiting pedantic test pilots, they're just doing their job, it's a regulatory requirement, which you may read here:

FAR Part 25 Sec. 25.173 effective as of 02/01/1965


so why aren't we back in the air?
Because the test pilots will require a demonstration of compliance with the above, and robustness of any systems which supplement that. I think they're going to be thorough!

I'm also imagining a review of (my bold):


Sec. 25.1309

[Equipment, systems, and installations.]

(a) The equipment, systems, and installations whose functioning is required by this subchapter, must be designed to ensure that they perform their intended functions under any foreseeable operating condition.
(b) The airplane systems and associated components, considered separately and in relation to other systems, must be designed so that--
(1) The occurrence of any failure condition which would prevent the continued safe flight and landing of the airplane is extremely improbable, and
[(2) The occurrence of any other failure condition which would reduce the capability of the airplane or the ability of the crew to cope with adverse operating conditions is improbable.
(c) Warning information must be provided to alert the crew to unsafe system operating conditions, and to enable them to take appropriate corrective action. Systems, controls, and associated monitoring and warning means must be designed to minimize crew errors which could create additional hazards.
..............

runner1021 21st Mar 2019 03:36

Ralph Nader, (who lost his grandniece on ET302), said MCAS "reflected a misguided view driven by engineering overconfidence" and referred to it as “the arrogance of the algorithms.” Seems a fitting description of the computer driven world we are now dealing with. (Or should that read the computer driven world that deals with us).....

patplan 21st Mar 2019 03:48

It's no longer anonymous. Parts of the Lion Air's PK-LQP CVR conversation leaks which propagated through many news sites have been confirmed by Nurcahyo Utomo, the head of the air accident subcommittee of the Indonesian National Transportation Safety Committee, who listened to and described the contents of the cockpit voice recorder that was retrieved from the ocean floor in January.

Some excerpts:
===============

Confusion, Then Prayer, in Cockpit of Doomed Lion Air Jet

...Indonesian aviation regulations bar the public release of a transcript of the audio in a cockpit voice recorder. But investigators from the National Transportation Safety Committee who listened to the recording described the sounds emanating from the cockpit as the flight crew fought to take control of a plane that seemed almost magnetically propelled toward earth.

Throughout the brief flight, an ominous rattle could be heard on the voice recorder, evidence that a device called a stick shaker was clattering to alert the pilots of a potential stall that could lead to a crash, said Ony Soerjo Wibowo, an air safety investigator. A stall can occur when a plane ascends too sharply...

...In the cockpit voice recording, the pilots discussed unreliable airspeed and altitude readings they were getting, national transportation safety officials said.

They consulted the manual to deal with these anomalies. But they did not seem to know about the MCAS system, nor did they speak about what was causing the plane to repeatedly push downward...

==============



- https://www.nytimes.com/2019/03/20/w...sh-boeing.html

ironbutt57 21st Mar 2019 04:00


Originally Posted by TowerDog (Post 10425332)


No..The MCAS System was there to meet certification requirements.

yup, poor or non standard handling characteristics in certain flight regimes, because of poor aerodynamics, the handling did not fall in line with certification requirements, thus this half assed system

Capn Bloggs 21st Mar 2019 06:47


GPS is a groundspeed indicator not an Airspeed indicator.
Verry simple said.
You fly into a headwind of 100 kts. with an airspeed of 100 kts. You GPS will indicate 0 kts. And your Airspeed indicator 100 Kts.
You turn your aircraft around and fly in that same headwind but now it is a tailwind. Your GPS indicates 200 kts. but your airspeed indicator still shows 100 kts.
Get your facts straight please.
Obviously never done a Unreliable Airspeed for real/sim. Had these 737s not continued to accelerate to almost Vmo at low level, the crews may well have been able to have more time to nut out what was going wrong; certainly, a lower speed would have given the stab less authority. Below 5000ft, the IAS will equal the GS, for all intents and purposes. You will not be doing 100IAS in a 737 and the wind won't be 100kts just after takeoff.

And on approach the GS is invaluable.

rmac2 21st Mar 2019 07:11

Yes Boeing did screw up with their design concept...

BUT after reading a lot of the to and fro here I have only three words to offer for when it's all going south on the panel

PITCH
POWER
TRIM

If she won't trim to the attitude you need for the known power setting that's a pretty BIG clue which system is not playing ball, particularly in day VMC which was the conditions for both accidents

DaveReidUK 21st Mar 2019 07:28


Originally Posted by Loose rivets (Post 10425283)
Oh, and the skipper not writing much detail into his report. I rather think it was 'The less said, the better - if we want to fly the next sector'.

Cynicism based on years of ordinary operational company-biased decision-making..

Your cynicism is justified. Any airline maintenance engineer will be familiar with the phenomenon where snags all seem to appear on the last sector inbound to base, and not down the line where the aircraft would have to be grounded for rectification.

But the Lion Air flight prior to the accident was returning to CGK, so that doesn't explain the failure to write up the issues properly in the Tech Log.

yanrair 21st Mar 2019 08:18

Hi Capn Bloggs
quite right. GPS is of no assistance in these situations. When your plane has been allowed to reach a near vertical descent GPS Will only confirm that it’s time for some flying skills.

Rated De 21st Mar 2019 08:19


Originally Posted by DaveReidUK (Post 10425399)
Your cynicism is justified. Any airline maintenance engineer will be familiar with the phenomenon where snags all seem to appear on the last sector inbound to base, and not down the line where the aircraft would have to be grounded for rectification.

But the Lion Air flight prior to the accident was returning to CGK, so that doesn't explain the failure to write up the issues properly in the Tech Log.

Normailisation of deviance.

Culture likely punitive.

Cows getting bigger 21st Mar 2019 08:27


Originally Posted by rmac2 (Post 10425396)
Yes Boeing did screw up with their design concept...

BUT after reading a lot of the to and fro here I have only three words to offer for when it's all going south on the panel

PITCH
POWER
TRIM

If she won't trim to the attitude you need for the known power setting that's a pretty BIG clue which system is not playing ball, particularly in day VMC which was the conditions for both accidents

Since Pontius was a pilot we've had trim runaways. Smart people train for that. REALLY smart people engineer away the problem. This thread, and others, according to CGB:

1. Boeing think they're going to get the hinds whipped by 320NEO. They dust-off some old drawings and add a couple of efficient engines.
2. Pesky certification requirements identify a force feedback issue at high AOA.
3. Boeing introduce a mechanism to falsely provide that feedback (basically trimming away from the pilot's input). Let's just think about that - a (hidden) automated mechanism that intentionally takes an aircraft out of trim.
4. Boeing don't put anything in the 'book' as they don't want to confuse pilots.
5. Crash 1.0
6. Crash 0.1 crew had something similar the day before. Jump-seat Hero sorted it (Why couldn't two crew figure the problem? Overload?)
7. Crash 0.1 crew and engineers didn't fully articulate and/or understand the issue. Did an occurrence report end-up on a Boeing database somewhere?
8. Boeing "Oh we have something called MCAS. It looks as if the logic may need a bit of tweaking but in the interim shove this extra page in your AFM."
6. US Government shutdown for 5 weeks - MCAS 2.0 is delayed.
7. Crash 2. "Hmmm, is this related?"

I don't see any point in specifically pointing fingers at a Seattle software engineer, a Government shutdown or under-trained, under-aroused crews - I see failures at numerous steps (Swiss cheese). There appears to be a lot of people/agencies who should be spending less time running around worrying about litigation and more time pulling-up their socks.

Nomad2 21st Mar 2019 08:27

Indeed Fizz.

And right there is the root of the problem.

And you know, if the nose keeps going down, and the only thing that's bringing it back up for you is the stab trim, there might be some reluctance to turn it off!

wbclay 21st Mar 2019 08:38

Which certification FAR?
 
Speaking of pedantic and in the old SAT tradition of "select the BEST answer among the choices given" ...

Is FAR Chapter 25, Sec. 25.203(a) more directly controlling, since it addresses "longitudinal control force" in approaching stall and does not combine the tactile feedback requirement with trim speed issues?

Surely not an important quibble. I'm just a non-pilot software engineer who's trying to follow the causal chain here and I may need to correct an assertion I have made elsewhere.

yanrair 21st Mar 2019 08:54


Originally Posted by Nomad2 (Post 10425439)
Indeed Fizz.

And right there is the root of the problem.

And you know, if the nose keeps going down, and the only thing that's bringing it back up for you is the stab trim, there might be some reluctance to turn it off!

Nomad
The thing that levels the plane is the yoke. You turn off the STAB. trim manually. Fly the plane. All before the STAB gets out of GREEN ZONE and into danger zone.

Nomad2 21st Mar 2019 09:02

yanrair.
Thanks for the reminder on how to fly. I remember exercise 1, "effects of controls" although it's some 13,000 hours ago for me.

Two crews were overwhelmed by these aircraft, so clearly it's not quite as simple as you suggest.

Shame you weren't in command I guess, it would all have been sorted out in a few seconds....,

fdr 21st Mar 2019 09:04


Originally Posted by Rated De (Post 10425430)
Normailisation of deviance.

Culture likely punitive.

Surely you jest sir! This is the best industry that money can buy. There is 40 years of rapacious investor appetite being counterbalanced by technical improvements in the operation and systems, and we hit a plateau some time back when it became noticeable to passers by that the pilots cannot fly planes any longer. The last 20 years we have poked smoking holes in the ground, punters have exclaimed in shock and indignation and then gone and paid the lowest amount that arbitrage of safety can buy.

Upshot is, the management system became reliant on unwavering compliance with procedures that sometimes help and sometimes hinder the task at hand. Consider the last time that you as an operating crew member had full compliance with all the rules that exist for your operation. Before anyone exclaims that we (you) are better than that, consider the last long haul flight you did out of say, JFK, where there were 165 pages of NOTAMS, and the crew had at least 10 minutes to plan for a 16 hour flight across the pole, in ETOPS or EDTO, in LVTO, with diversion fields in Siberia etc... The rules are meaningful when they can be applied readily, not requiring a QC to interpret the FDTL, FCL, and the rest of the BS that adds to the ZFW of the plane.

Considering how many operations out there are punitive, a long time back a disgruntled resident showed his/her displeasure with the local government by planting a rather large fireworks/ stick of gelignite outside of the govt chambers at night. The next morning, the doors were well askew. The local police were soon on the crime scene, and after a short while, the mayor asks the investigators if he has any suspects. The investigator leant over a counter and grabbed the local phonebook, handed to the mayor and said, "anyone between the covers".

Punitive culture is what the industry has developed. CRM, TEM, MEDA, and the rest of the acronyms are lipstick on the pig, there for show.

Wish the world was different, but there it is. Aviation is big money flows, with low margins, and the culture is a consequence of the reality.

yanrair 21st Mar 2019 09:24

Dear Fizz57
But you're not left with a Cessna - the 737's (the later ones at least) do not meet certification requirements with the bells and whistles turned off. That's why they were put in in the first place.
I think I am one of the few on this forum who has flown the real 737, not a sim. - later variants up to the -800 still in production (pre MAX obviously ) with pretty much everything turned off except the battery.
No hydraulics. No AC power. No anything but me and some 12mm wire joining me to the controls. And yes, I still have the STAB because is is trimmed MANUALLY!
I don't get your comment "not certified". A 737 can fly with no computers or indeed no pretty much anything working, and this is demanded on the FAA test flights which I have conducted to make sure it works. If this has changed on the MAX then that is something to ponder most seriously. But I doubt it.
So as a previous thread says" PITCH& POWER" and that is the key. If you fly 6 nose up and 60% power you can fly all day and it will not crash. Well, until you run out of fuel. That gives you loads of time to sort out all the other stuff going on. If you suffer total loss of airspeeds, multiple stick shakers, one airspeed saying 500 and the other saying zero and lots of horrible noises and verbal alerts going on - how do you decide which is right and which is wrong?. [Not sure it was a anything like as bad as this on these two by the way, but that is the worst case]. You level the wings, 6 deg pitch and set the power midway. Calm is restored. Switch off the offending systems. Fly manually. Re-engage any working automatics.


Cheers and thanks for the chat folks
Yanrair


I have been finding it hard going, we all have, with the to and fro of highly complex technical jargon and solutions. The solution is to fly the plane. If AF 744 had done this, and many many others, we would have had far fewer accidents.
Are modern pilots good enough to do this? Well, I have a view on that.

By the way there is another theme here on this topic. That everything needs to be automated out. What about landing in 60 knots of wind with bad turbulence in 300 metres visibility and 200 foot cloud base in pouring rain? That is a challenge and is done manually every time, since no autopilot can get anywhere near dealing with the complexity of such conditions and the endless permutations required to achieve a safe touchdown. Windshear Go Arounds are manual. Get it wrong and we are in God's Parlour. GPWS terrain impact avoidance is flown manually using the stick shakers to fly right into the stall, but not beyond, to safety fly over the obstacle.
There are so many of these we can't deal with them now but one thing they are not is automated.
Yanrair



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yanrair 21st Mar 2019 09:30

yanrair.
Thanks for the reminder on how to fly. I remember exercise 1, "effects of controls" although it's some 13,000 hours ago for me.

Two crews were overwhelmed by these aircraft, so clearly it's not quite as simple as you suggest.

Shame you weren't in command I guess, it would all have been sorted out in a few seconds....,


That is a cheap shot. Sully and hundreds of pilots like him have achieved things I could maybe not have achieved, but I do know how to!! Al Haines, Sioux City - look at that one on tube. BA 747 over Jakarta All four engines flamed out. Safe landing. Not in the "book" that some of you guys are referring to. Lots of stuff in not in any book. These two were. STAB RUNAWAY.
BA 777 Heathrow couple of years ago. Saved 400 lives using pure flying skills. Double engine failure like Sully. I have been involved in training a major airline recently and all these skills are taught and practised including landing with no engines.
Cheers

ZAZ 21st Mar 2019 09:36

Speaking of the books
Cockpit voice recorder alleges capt and FO both flying plane for nine minutes each trying to look up stuff in the flight ops books.
Last heard saying goodbye.
not that it helped.

Cows getting bigger 21st Mar 2019 09:50

yanrair, for every Hero, there's a Zero - that's the law of averages. Pilots are no longer heroes, nor should they be. A safe system is one that reduces risk as low as reasonably practical and, whether we like it or not, a human being brings a huge pile of risk to any system. Pilots are not masters of the system, we are a part of it. For sure, these two crashes may have been avoided by the flick of two switches. But that wasn't the way it worked out and many of us think it rather disingenuous to pile the overwhelming burden of responsibility on the Zeros pilots.

"Just flick the switches and revert to manual" - that is confirmation bias at it's worst, being indicative of an industry that no long takes an active role in looking at itself.


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