Ethiopian Airlines Crash/ B737MAX grounding

billy few mates

coastwatch wrote: »

Another novice here. Would this crash have happened if the flight was on Autopilot? Does the Autopilot system use the same sensors (faulty) as the MCAS?
From what I have read, the MCAS only activates when autopilot is off.

MCAS is only active in manual flight so it wouldn't have happened if the autopilot was engaged. There are three ways to trim the aircraft, manually by rotating the trim wheel, electrically by operating the pickle switches on either control column and the third way is via the autopilot where the FCCs automatically trim the aircraft through a separate trim servo mounted on the screwjack beside the normal electric trim servo.
With the autopilot engaged it's normal to see the trim wheels rotate as the autopilot trims the aircraft. In manual flight the only time they would see the trim wheels turning is if they're trimming the aircraft themselves via the trim switches or by manually winding the trim wheel.
If the crew knew nothing about MCAS and they saw the trim wheels turning in manual flight they'd naturally assume it was stabiliser runaway.
This is almost exactly the same as what happened in the early days of the 737 classic when crews transitioning from the -200s saw speed trim operating for the first time when they took off and the ST system briefly applied a 'burst' of stab trim to trim the aircraft which they weren't expecting and incorrectly reported as stabiliser runaway.
But as we now know MCAS has a lot more authority over the aircraft than ST...

coastwatch

Thanks for the very informative reply

gctest50

OSI wrote: »

There are, but Boeing specifically stated that pilots don't need training on it if they've already flown other 737s and supposedly the simulator can't even simulate the MCAS issues.

And that was the problem, they weren't really pilots, more like three quarter programmed androids

how could they miss this kinda thing ?

the spinning wheel of death must be the most obvious thing surely ?

how could they miss these ?

right beside the spinning wheels of death :

cnocbui

Everyone using hindsight is an expert.

odyssey06

gctest50 wrote: »

And that was the problem, they weren't really pilots, more like three quarter programmed androids ... how could they miss this kinda thing ?

Right. How could Boeing miss all the things they missed???
Sure maybe more experienced better trained pilots would have saved the day, but why the **** should they be having to save the day from a dangerously designed aircraft? This isn't wartime and they are rushing out a new plane with improved capabilities to keep up with an arms race.

If only Boeing hadn't used a single sensor, instead of a dual sensor, calibrated on the deck.
If only Boeing had stuck to the original capabilities of the MCAS they submitted to the FAA.
If only there was some pilot certification for variants of an aircraft, without having to go through full recertification, then maybe Boeing would have done the obvious things like putting how to disable MCAS into simulators and the flight manual; instead of engaging into a gigantic scam.
If only the LION air crew who had to rely on a passenger pilot to disable MCAS had mentioned something to the next crew.
If only LION air had grounded the plane after the first incident and demanded answers from Boeing.
If only Boeing hadn't waited for a second one of their planes to crash and kill everyone on board before issuing a software update for MCAS.

If only the authorities had grounded the 737 NG after the first crash when it was obvious it was an accident waiting to happen and needlessly kill hundreds of people.

If only Boeing could still design a safe plane and be honest about what they have done.

Inquitus

gctest50 wrote: »

And that was the problem, they weren't really pilots, more like three quarter programmed androids

how could they miss this kinda thing ?

the spinning wheel of death must be the most obvious thing surely ?

how could they miss these ?

right beside the spinning wheels of death :

Stick shaker, warnings, 1000ft of altitude and a checklist you are supposed to refer to in the case of issue. It's easy now we all know what they should have done, but its quite another thing executing this in the most dangerous phase of flight with no altitude to play with. The blame here lies solely with Boeing, The FAA and the self certification of a dangerous system, without input redundancy, that can aggressively trim the aircraft nose down over and over again unless disabled.

gctest50

Inquitus wrote: »

Stick shaker, warnings, 1000ft of altitude and a checklist you are supposed to refer to in the case of issue. It's easy now we all know what they should have done, but its quite another thing executing this in the most dangerous phase of flight with no altitude to play with. The blame here lies solely with Boeing, The FAA and the self certification of a dangerous system, without input redundancy, that can aggressively trim the aircraft nose down over and over again unless disabled.

There is a wire rope all the way from those spinning wheels all the way to the tail same as before


This whole thing is not a new thing -eg if the brakes fail on the setup, the force on it from the air flowing over it may cause it to move

or the computer/relay/wiring goes daft, it will run away by itself and you might end up stuck in the ground like a dart

turn off the electrics to it, if it stops, it was electrical

if it doesn't stop, it airflow/somethings failed

start winding the spinning wheel fairly lively so and put it back to where it should be before you crash hopefully

gctest50

If this creation fails badly, everyone dies :

gctest50

Drum with cables underneath that thing in the post above :

Phil.x

I think they will "quickly" come out with a new variety of the 737 and banish the max to the history books.

L1011

Phil.x wrote: »

I think they will "quickly" come out with a new variety of the 737 and banish the max to the history books.

Cost of that would be tens of billions between cancelled orders, compensation and development costs.

The cheap option is to get a software fix out there, make the "options" standard and retrofit them to the existing fleet; maybe look at an STC for a third AoA sensor and voting. And hope there isn't another horror waiting to appear.

Jeff2

cnocbui wrote: »

Everyone using hindsight is an expert.

In hindsight.
Corners were cut to get a product to market at all cost.

Safety was compromised to get a plane out with no new training even though it had new bigger engines moved forward and had a electronic system that could bypass the pilot.

No, if I knew all this I'd not fly on one.

murphaph

gctest50 wrote: »

There is a wire rope all the way from those spinning wheels all the way to the tail same as before


This whole thing is not a new thing -eg if the brakes fail on the setup, the force on it from the air flowing over it may cause it to move

or the computer/relay/wiring goes daft, it will run away by itself and you might end up stuck in the ground like a dart

turn off the electrics to it, if it stops, it was electrical

if it doesn't stop, it airflow/somethings failed

start winding the spinning wheel fairly lively so and put it back to where it should be before you crash hopefully

How much do the wheels spin when deflecting the stab by 2.5°? Would you see this if your head was buried in a checklist 1000ft off the ground? Boeing gave these guys no chance. It's not remotely fair to blame it on either flight crew.

cnocbui

Jeff2 wrote: »

In hindsight.
Corners were cut to get a product to market at all cost.

Safety was compromised to get a plane out with no new training even though it had new bigger engines moved forward and had a electronic system that could bypass the pilot.

No, if I knew all this I'd not fly on one.

I was referring to the post directly above mine.

mickdw

Does the autopilot take similar sensor info to mcas and if so does it take it from a different sensor or multiple sensors or what.
I understand that this particular fault will only occur with autopilot off but is there a similar fault possible while on autopilot if a different sensor was to malfunction for example.

jimmycrackcorm

cnocbui wrote:

I wouldn't be surprised if an MCAS simulation update for the 737 Max in X-Plane 11 didn't come out before Boeing has one.

And every max pilot rushes out to get it.

Cloudio9

murphaph wrote: »

How much do the wheels spin when deflecting the stab by 2.5°? Would you see this if your head was buried in a checklist 1000ft off the ground? Boeing gave these guys no chance. It's not remotely fair to blame it on either flight crew.

Plus apparently something like 40kg of pullling force needs to be applied to the control column to keep the nose up. That must get exhausting pretty quick.

Anyone know if there are cases of this issue which have been recovered ( apart from the earlier lion one with the third pilot)?

billy few mates

murphaph wrote: »

How much do the wheels spin when deflecting the stab by 2.5°? Would you see this if your head was buried in a checklist 1000ft off the ground? Boeing gave these guys no chance. It's not remotely fair to blame it on either flight crew.

I can't say exactly how many full cycles of the trim wheels are required for 2.5° stab trim but on the 737 you would definitely notice them turning. There's quite a loud mechanical clattering when it's moving, the black wheels have white stripes painted on them for visual cue and if the fold out handle is extended when the trim wheels rotate you'll soon know about it as it will whack you right in the shin.

billy few mates

mickdw wrote: »

Does the autopilot take similar sensor info to mcas and if so does it take it from a different sensor or multiple sensors or what.
I understand that this particular fault will only occur with autopilot off but is there a similar fault possible while on autopilot if a different sensor was to malfunction for example.

The alpha vanes fitted to 737s fail passively when they fail, ie they don't really cause any adverse problems because (apart from MCAS) they don't really have any direct authority on any system. They're quite a simple device, it's basically a torque synchro which gives an electrical signal to the stall management computer(s) but they're quite sensitive so have to be handled with extreme care. The most common failures are the heater element (they're heated to prevent freezing up) or mechanical wear or striction. Normally you only know they've failed when you can't test the stall warning system using the test switches on the P5 panel. Even then you'd have to do do a bite check on the computer to know it was the faulty component.

Tenger

cnocbui wrote: »

Everyone using hindsight is an expert.

Spot on.
I read an article about 4-5 years ago about the MAX program. It was making the point that the MAX was an act of desperation from Boeing. The A320 was doing so well and they had lost so much in the development of the B787 that they werent able to follow their plan for the 'B797' as a B737 replacement. Thus, to keep themselves competitive they had to stretch the B737 design even further. The A320, being a much newer design had 2 more upgrade cycles possible and Boeing knew they couldnt get the 'B797' in the air before the then proposed A320neo.
At the time I read it purely as an opinion on commercial priorities, and it did present itself as just that.
Hindsight gives insight that wasnt there at the time.

Personally the whole affair is saddening. 300 lives lost over a software issue put in place to save money.

Widdensushi

Tenger wrote: »

Spot on.
I read an article about 4-5 years ago about the MAX program. It was making the point that the MAX was an act of desperation from Boeing. The A320 was doing so well and they had lost so much in the development of the B787 that they werent able to follow their plan for the 'B797' as a B737 replacement. Thus, to keep themselves competitive they had to stretch the B737 design even further. The A320, being a much newer design had 2 more upgrade cycles possible and Boeing knew they couldnt get the 'B797' in the air before the then proposed A320neo.
At the time I read it purely as an opinion on commercial priorities, and it did present itself as just that.
Hindsight gives insight that wasnt there at the time.

Personally the whole affair is saddening. 300 lives lost over a software issue put in place to save money.

I can only relate 2 this on a marine level but it's similar when you are in a new or new to you a problem can be major but when a problem has occurred previously and you know how to remedy it it's minor.

Jeff2

Tenger wrote: »

Spot on.
I read an article about 4-5 years ago about the MAX program. It was making the point that the MAX was an act of desperation from Boeing. The A320 was doing so well and they had lost so much in the development of the B787 that they werent able to follow their plan for the 'B797' as a B737 replacement. Thus, to keep themselves competitive they had to stretch the B737 design even further. The A320, being a much newer design had 2 more upgrade cycles possible and Boeing knew they couldnt get the 'B797' in the air before the then proposed A320neo.
At the time I read it purely as an opinion on commercial priorities, and it did present itself as just that.
Hindsight gives insight that wasnt there at the time.

Personally the whole affair is saddening. 300 lives lost over a software issue put in place to save money.

Do you think if you take one plane and make it longer and change the engines and there position with a new MCAS system that the pilot should know

Jeff2

If I went out to ride my mates motorbike that is the same as mine and it was longer or higher or more powerful I'd like to know before going out.

Captain_Crash

Cloudio9 wrote: »

Anyone know if there are cases of this issue which have been recovered ( apart from the earlier lion one with the third pilot)?

I can’t find the link but I believe it was on CNN where they mentioned there had been 6 similar occurrences in the US that were reported! The article did state that they can’t say if they were the same MCAS issues or not, nor did it state how they were recovered so take it as you will.

Mebuntu

If you want to know where the grounded MAX's are located this may help:-


https://www.flightradar24.com/blog/where-the-grounded-737-max-are-stored/

Shn99

Software fix out
https://m.economictimes.com/news/international/world-news/fix-to-mcas-anti-stall-software-in-737-max-ready-to-go-boeing/articleshow/68541920.cms

basill

Not approved by FAA as yet.

cnocbui

Shn99 wrote: »

Software fix out
https://m.economictimes.com/news/international/world-news/fix-to-mcas-anti-stall-software-in-737-max-ready-to-go-boeing/articleshow/68541920.cms

A great epitaph for a headstone.

basill wrote: »

Not approved by FAA as yet.

Is FAA approval relevant any more?

Damien360

basill wrote: »

Not approved by FAA as yet.

Considering their previous involvement with regards to self certification by manufacturers and severe lack of oversight, I wouldn't hold much faith in what the FAA pronounced about that fix. A wholesale change of policy is required and they may need to use a large stick to Boeing to regain credibility.

basill

Remember EASA and various other overseas regulators have stated that they are undertaking a root and branch review. Rolling out a software fix and getting the FAA to sign it off doesn't necessarily mean it will be able to fly outside the US.

Is FAA approval relevant any more?

My understanding was that the FAA has always had to give approval and this never changed. The donkey work of the certification was contracted back to Boeing and the FAA signed off based on the former demonstrating that it had fulfilled its compliance requirements. The buck still stops with the FAA. In light of the crashes I would say getting an FAA sign off may well be just a little bit harder. There is also a US inquiry going on into the FAA oversight process.