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Another 737 max has crashed during departure in Ethiopia
14

Another 737 max has crashed during departure in Ethiopia

Another 737 max has crashed during departure in Ethiopia

(OP)
Another 737 max has crashed during departure in Ethiopia.

To note the data in the picture is intally ground 0 then when airborne is GPS altitude above MSL. The airport is extremely high.

The debris is extremely compact and the fuel burned, they reckon it was 400knts plus when it hit the ground.

Here is the radar24 data pulled from there local site.

It's already being discussed if was another AoA issue with the MCAS system for stall protection.

I will let you make your own conclusions.




RE: Another 737 max has crashed during departure in Ethiopia

Surely after tge Lion Air crash, 737 max pilots must be aware of the issue and how to solve it?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Another 737 max has crashed during departure in Ethiopia

That altitude variation at the end looks awfully suspicious. It's hard to believe the pilots wouldn't know what to do, though.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Well they put through a software "fix" to the system I believe.... but not sure if it was mandatory or not.

There is still only 1 simulator in the world that actually simulates this MCAS system.

The official Boeing differences training is a 3 hour CBT between the NG and MAX no simulator time is mandated. Just do the CBT and go and fly.


This phase of flight is statistically one of the safer phases and two aircraft of a new type in the space of 6 months crashing in that phase is highly unusual and to be honest extremely worrying.

RE: Another 737 max has crashed during departure in Ethiopia

I thought the pilots could easily disengage the new attitude system and surely after the 1st crash they would have been thinking about it all the time, no? Maybe the AoA sensor failed and they couldn't fly the plane without it. How hard is it to maintain the proper AoA on that kind of plane without functioning instruments? I don't usually worry at all about flying, but right now I would have to think hard about flying on the Max.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Its pretty easy on any plane you just set an attitude either by looking out the window, looking at the artificial horizon or maintaining the book airspeeds.

This MCAS system takes the AoA reading and then applies forward trim if it thinks the plane is going to stall while manual flying with the flaps up. Full forward trim is 45kg stick force for level flight.

There is an easy trained way of getting rid of the trim system.


But its spotting there is a problem and then realising what the problem is. They were in the air 180 seconds before they crashed.

Memory items for our quickest procedure which is the fire evacuation on the ground take 50 seconds which is quick, the 737 has to put flaps down first so takes 2 mins.



An aircraft type should not be in the air if the pilots have to presume there is going to be a trim runaway as soon as the flaps come up.

RE: Another 737 max has crashed during departure in Ethiopia

Wonder if there is going to be a recall? Or will there have to be a crash on a western carrier before Boeing takes action?

RE: Another 737 max has crashed during departure in Ethiopia

Give it about a week. If Boeing does't escalate its response to this flaw by then, I believe it will require condition "b" to provoke it.

I would like more insight into how the Southwest Airlines' pilots union is reacting to this. They have the most at stake, having the biggest order of these aircraft so far. What can be read of the SWAPA union press releases contains normal griping concern about not being consulted on issues related to the evolution of the 737 to the new Max variant, but little about the MCAS system. I have found nothing written by persons who display an adept understanding of aircraft control systems in the press releases (why should I expect it?).

So if the pilots are not concerned should we be not concerned?

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
the first section the flap will have been down for takeoff so the MCAS system won't be turned on yet.

1000ft agl is acceleration when the flap would come up.

As the AoA also controls the stick shaker then I would expect one side to be running in phase 2 climb. You can see the level off phase 3. Then decent in phase 4 when the MCAS kicked in when flaps retracted.

4000ft per min is nothing special to be honest at 9000ft MSL clean and 350+ knots. Which is way over the Vmo of the aircraft.

RE: Another 737 max has crashed during departure in Ethiopia

You mean altitude not acceleration?

Does the MCAS shut off with any flaps or only with full flaps?

Keith Cress
kcress - http://www.flaminsystems.com

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
We call it acceleration altitude which is when we come out of takeoff configuration and speeds which is normally V2 +10 and 1 or 2 stages of flap and into climb mode.

You level accerate to V climb retract the flaps and climb away at that.

With any stage of flap the MCAS system is not required to ensure stability. Flaps move the center of pressure inboard and to rear increasing stability in pitch and decreasing it in roll.

It's required because the center of thrust is lower with leap engines giving an increased nose pitch up with power. So the MCAS is meant to automatically pitch the nose down.

RE: Another 737 max has crashed during departure in Ethiopia

I think this is the best place to get news for all things aviation, and their thread for this accident;

https://www.airliners.net/forum/viewtopic.php?f=3&...

It's all just rumor and speculation at this point.

Brad Waybright

It's all okay as long as it's okay.

RE: Another 737 max has crashed during departure in Ethiopia

I enjoy that site but it is not very well moderated. That thread is mostly quarreling to this point.

RE: Another 737 max has crashed during departure in Ethiopia

There have been what, 350 of them delivered, and two have crashed in relatively similar ways?

That's a pretty high percentage.

RE: Another 737 max has crashed during departure in Ethiopia

Quote (TenPenny)

There have been what, 350 of them delivered, and two have crashed in relatively similar ways?

That's a pretty high percentage.
...and I wonder how many white knuckle moments that didn't make the news? ponder

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Another 737 max has crashed during departure in Ethiopia

The missing three minutes are shown on this map. Look like the pilot had made a right turn to try to get back to the airport but from the crater seems to have gone in near vertical at high speed. Hope the FDR and CVR give us some data about what was going on.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
It's uk airspace so it's basically blocked them being used transatlantic.

RE: Another 737 max has crashed during departure in Ethiopia

News: "Germany, Ireland and France ban Boeing 737 Max 8 planes from airspace"

RE: Another 737 max has crashed during departure in Ethiopia

Over 4 months without a fix.
They could have at least pulled a fuse or disconnected a wire.
A simple alarm rather than computer directed flight into terrain.
Instead they delayed until another 157 people died.
Are there any calls yet for criminal charges against Boeing executives.
Unbelievable and shameful.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

Well, I see now that 'Einstein' shouldn't be flying the planes, so let's all go back to wooden biplanes and sticks!

RE: Another 737 max has crashed during departure in Ethiopia

Such an embarrassment...

RE: Another 737 max has crashed during departure in Ethiopia

That map from the guardian is inaccurate, below is the co-ordinates for the crash site.

https://earth.google.com/web/@8.87673473,39.250979...

lots of speculation on this accident on the airliners forum. 35 pages of mostly speculation and rehashing mis-information on the MCAS system and it's operation, and a lot of back and fourth about if the Type should be grounded. There is a couple of nuggets of info but sorting through it all is a mess.

RE: Another 737 max has crashed during departure in Ethiopia

There are so few facts to choose from. I can't tell if the European no-fly orders are politically motivated or have technical merit.
I'm still trying to learn the function and purpose of the MCAS system.
This helps:
http://www.b737.org.uk/mcas.htm

It repeats the conditions when MCAS is active (autopilot off, flaps up). The description on that site makes it seem more like a thrust compensation device. Engines are mounted down low, so when the throttles are pushed forward, Boeing chose to "tweak" the elevator trim to compensate for the nose-up pitch. It just doesn't seem like this system can back off, or reverse the compensation when the throttles are eased back. In fact, if you consider that the pilots have manual control over the pitch anyway, giving them full authority over the airspeed, too, this system should be backing off the compensation almost immediately after it activates. If I understand its function right, it works in chunks of 2.5 degrees at a time - pretty big chunks of elevator pitch change to give out all at once.

In 100 years, there have been many aircraft with thrust-lines far off-center from the center of drag. In fact, it's common. It doesn't take much to be noticeable. I was exposed to it in basic training on a Cessna 172 doing go-arounds. When aborting a landing you have to get the flaps up and slam on the throttle, so you have to be ready for both the torque and wicked nose-up motion by doing both of those things at the same time. Pilots who can't deal with pitch changes associated with thrust changes get weeded out of the talent pool long before they are charged with passengers.

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Another 737 max has crashed during departure in Ethiopia

Quote (SparWeb)

There are so few facts to choose from. I can't tell if the European no-fly orders are politically motivated or have technical merit.
I heard this morning that the Ethiopian authorities are holding the black boxes and can't access the data. I don't know if that's true but if so this seems totally irresponsible and negligent. Otherwise, from what I have been able to find out, anything related to the cause of this crash is simply speculation. The Lion Air crash was apparently caused by a faulty AoA sensor and the MCAS incorrectly trying to compensate for the bad data from it. A contributing primary factor was the pilots inability or lack of knowledge about how to respond to that situation. Also, this condition had existed for several previous flights for this airplane and it should not have been left to fly until the problem was corrected. To attribute the latest crash to airplane design without some empirical evidence to support the claim is just irresponsible. That's the world we live in today, though.

Brad Waybright

It's all okay as long as it's okay.

RE: Another 737 max has crashed during departure in Ethiopia

It changes at 0.27 degrees per second. The limit is 2.5 degrees of change which would occur over 9.26 seconds.

RE: Another 737 max has crashed during departure in Ethiopia

Quote (thebard3)

I heard this morning that the Ethiopian authorities are holding the black boxes and can't access the data. I don't know if that's true but if so this seems totally irresponsible and negligent. Otherwise, from what I have been able to find out, anything related to the cause of this crash is simply speculation. The Lion Air crash was apparently caused by a faulty AoA sensor and the MCAS incorrectly trying to compensate for the bad data from it. A contributing primary factor was the pilots inability or lack of knowledge about how to respond to that situation. Also, this condition had existed for several previous flights for this airplane and it should not have been left to fly until the problem was corrected. To attribute the latest crash to airplane design without some empirical evidence to support the claim is just irresponsible. That's the world we live in today, though.

https://www.washingtonpost.com/world/africa/ethiop...

Ethio­pian Airlines announced Wednesday that it would send the voice and data recorders from its ill-fated Flight 302 to be analyzed abroad, as more countries said they were banning planes of the same type from operating in their airspace.
...
Ethio­pian Airlines Chief Executive Tewolde Gebremariam told CNN on Tuesday that the pilot reported “flight control problems” and asked to return to the airport.
...
Tewolde told CNN that the boxes would be sent abroad “because we don’t have the equipment here” to analyze their data. He said the boxes could possibly go to the United States or to a European country closer to Ethi­o­pia “in the interest of proximity and speed.” The decision will be made by the team investigating the crash.
...
In both the Lion Air and Ethio­pian Airlines crashes, the airplane immediately showed signs of trouble, with an erratic flight path that ascended and then descended before the airliner crashed minutes later.

RE: Another 737 max has crashed during departure in Ethiopia

Quote (thebard3)

I heard this morning that the Ethiopian authorities are holding the black boxes and can't access the data. I don't know if that's true but if so this seems totally irresponsible and negligent.

Perhaps you're misinterpreting.

"Ethiopian authorities are holding the black boxes..." ...perhaps while they're making arrangements to have them sent to a suitable facility for reading out the data. They'd be holding them in a secure location, as evidence. It's the sort of secure transportation arrangements that could quite reasonably require a couple of days.

"...and can't access the data." There are probably a hand-full of suitable facilities in the world that can read the data from the boxes (which may be heavily damaged). So it's perfectly reasonable that the Ethiopian authorities can't access the data themselves. Even if they could try, it would be safer to let the experts (such as the OEM) do it.

So I don't see anything that's remotely irresponsible and negligent.

Hopefully I'm not misinterpreting what you've posted.

Did you want to clarify?

RE: Another 737 max has crashed during departure in Ethiopia

Quote (VE1BLL)

Perhaps you're misinterpreting.

I sometimes exhibit poor choice of words. This crashed happened Sunday and the data recorders were found quickly. It just seems to me an unreasonable delay to have not made a decision on where to have them analyzed still on Wednesday.

BTW- A pilot reporting 'flight control problems' means just about anything could be wrong. Immediately assuming this has any similarities to the Lion Air crash is just pure speculation, IMHO. The recorder data will quickly clear things up and identify a need (or unnecessary step) to ground the fleet.

Brad Waybright

It's all okay as long as it's okay.

RE: Another 737 max has crashed during departure in Ethiopia

Canada has now grounded the 737 Max 8 and 9.

CBC: "This safety notice restricts commercial passenger flights from any air operator, both domestic and foreign, of the Boeing 737 MAX 8 and 9 aircraft from arriving, departing, or overflying Canadian airspace," Transport Minister Marc Garneau said Wednesday. Garneau said the decision was made after his department received new information.

RE: Another 737 max has crashed during departure in Ethiopia

Quote (VE1BLL)

Garneau said the decision was made after his department received new information.
Can't wait until someone shares that with us.

Brad Waybright

It's all okay as long as it's okay.

RE: Another 737 max has crashed during departure in Ethiopia

"...happened Sunday and the data recorders were found quickly."

Reportedly, the data recorders were found on Monday.

RE: Another 737 max has crashed during departure in Ethiopia

And now the USA...

CBC News: "U.S. President Donald Trump issued an 'emergency order' grounding all Boeing 737 Max 8 and Max 9 a few hours after Canada's decision."

RE: Another 737 max has crashed during departure in Ethiopia

Because tRump is such a recognized aviation safety authority ...

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Another 737 max has crashed during departure in Ethiopia

4

Quote (thebard3)

the Ethiopian authorities are holding the black boxes and can't access the data. I don't know if that's true but if so this seems totally irresponsible and negligent. Otherwise, from what I have been able to find out, anything related to the cause of this crash is simply speculation. The Lion Air crash was apparently caused by a faulty AoA sensor and the MCAS incorrectly trying to compensate for the bad data from it. A contributing primary factor was the pilots inability or lack of knowledge about how to respond to that situation. Also, this condition had existed for several previous flights for this airplane and it should not have been left to fly until the problem was corrected. To attribute the latest crash to airplane design without some empirical evidence to support the claim is just irresponsible.

Just a friendly comment. They've been spatting about just these questions for 30+ pages on airliners.net and I hope to be civil here with you guys as always.

Anyway, doesn't this kind of beg the question to say it is irresponsible on both fronts? I can see how urgency on both would be warranted. Some of the groundings may be motivated by political or corporate interests, and these are not necessarily irresponsible, they are just different than technical grounds. It forces Boeing to resolve this with more urgency than they seem to have shown. It looks bad for them to be talking about a software patch the day after these two incidents.

At any rate, I think a simple risk matrix can be used to support a grounding, even with as little as we know. Two brand new Max 8 apparently fly themselves into the terrain on a clear day with experienced pilots reporting control issues, killing all souls on board. That weighs heavy on the consequence side of the equation even if the probability is low or non-existent for most of the 300+ planes in the fleet.





RE: Another 737 max has crashed during departure in Ethiopia

Agreed, commercial aviation should be one of the most risk-adverse fields out there. There have been two crashes, of the same make/model, relatively soon after the model was released. I would think that's enough justification to put them on the ground and see what's going on and determine what (if anything) needs to be addressed.

RE: Another 737 max has crashed during departure in Ethiopia

...and that Boeing is now putting a worldwide grounding in place (though with an FAA ban in place and no access to any of the major worldwide hubs, this could be a case of bowing to the inevitable).

A.

RE: Another 737 max has crashed during departure in Ethiopia

Quote (charliealphabravo)

At any rate, I think a simple risk matrix can be used to support a grounding, even with as little as we know. Two brand new Max 8 apparently fly themselves into the terrain on a clear day with experienced pilots reporting control issues, killing all souls on board. That weighs heavy on the consequence side of the equation even if the probability is low or non-existent for most of the 300+ planes in the fleet.
I sort of agree, but regarding the previous crash, I have a hard time blaming the aircraft design although it seems the MCAS was perhaps a contributor. It flew several previous flights with a known hardware issue that was never properly repaired. Also, there is an assumption that this crash is somehow related to the first, although as far as we know here there is no evidence yet to support that. Assuming they are related to the MCAS, new aircraft always require some type of in service modification/improvement just like anything else. I guess you just hope that an issue like this would be identified and corrected without people losing their lives.

Brad Waybright

It's all okay as long as it's okay.

RE: Another 737 max has crashed during departure in Ethiopia

Quote (RVAmeche)

Agreed, commercial aviation should be one of the most risk-adverse fields out there. There have been two crashes, of the same make/model, relatively soon after the model was released. I would think that's enough justification to put them on the ground and see what's going on and determine what (if anything) needs to be addressed.
I wish I had just said that instead.

Brad Waybright

It's all okay as long as it's okay.

RE: Another 737 max has crashed during departure in Ethiopia

Caught a glimpse of the Ethiopian crash site on the local news... it showed a bulldozer pushing large masses of scrap metal into even larger masses. Someone please tell me they're not making the site more "tidy" by using a bulldozer. I thought immediate course of action was to collect all pieces of the aircraft and reconstruct in a local hangar, making careful note of where each piece was found.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Another 737 max has crashed during departure in Ethiopia

I agree it doesn't look like a very "secure" site, but the level of destruction is unreal, it all basically buried itself several metres down in what is apparently quite soft ground out there having gone in near vertical by the look of things.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Another 737 max has crashed during departure in Ethiopia

Apparently there is a way to turn off the MCAS with a switch in the console between the pilots. Can anybody verify this with a picture? I'd like to update our article (below) with that information.

From my research for the article, I found that not all pilots were informed of the MCAS or the cut off switch. The head of one pilots union said words to the effect of "Why should they know? I don't know how my TV works."

https://www.engineering.com/ElectronicsDesign/Elec...

Roopinder Tara
Director of Content
ENGINEERING.com

RE: Another 737 max has crashed during departure in Ethiopia

From the discussion of the Lion Air crash it appears that every time the pilots turned the system off, it turned itself back on.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

Roopinder,

See this which is the best diagram and photo I've ever seen on the lion Air crash. https://www.nytimes.com/interactive/2018/11/16/wor...

I still think they are talking about the STAB TRIM CUTOUT switches in the centre console below the throttle levers.

The manual trim switches on the yoke can override the trim position but only for a few seconds.

Now how you manage to flick the safety covers out the way and flick those switches down while the plane is going haywire and bouncing around is another thing. Also you need to do both at the same time by the look of it (can a pilot confirm this?)

If you only manage one and then the system kicks in I can only imagine one trim going one way while the other stays put won't be good.





Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Another 737 max has crashed during departure in Ethiopia

Quote (RoopinderTara)

Apparently there is a way to turn off the MCAS with a switch in the console between the pilots. Can anybody verify this with a picture? I'd like to update our article (below) with that information.

It was already posted by SparWeb. This link has a picture. http://www.b737.org.uk/mcas.htm

However, the switches don't disable the MCAS, they disable the motor operating the stabilizer. Then, the pilots have to manually control it.

RE: Another 737 max has crashed during departure in Ethiopia

Quote (MacGyverS2000)

Caught a glimpse of the Ethiopian crash site on the local news... it showed a bulldozer pushing large masses of scrap metal into even larger masses. Someone please tell me they're not making the site more "tidy" by using a bulldozer. I thought immediate course of action was to collect all pieces of the aircraft and reconstruct in a local hangar, making careful note of where each piece was found.

As he spoke, a bulldozer dumped more debris from the plane into a huge pile in front of the assembled mourners, while men wearing white masks and carrying plastic bags picked through the dirt.

The plane plowed nose down into the earth, and much of the wreckage was buried at least 60 feet deep, said Zhang Jun, a construction engineer working at the site.

He brought his back hoe and bulldozer from Addis Ababa, where he was working on an airport construction project.

“It is in the soil very deep,” he said of the aircraft debris. “The pieces are very small, no more than two meters [about 6 ½ feet] long, he said. The human remains he found, he added, “were even smaller.”


https://www.washingtonpost.com/world/africa/at-eth...

RE: Another 737 max has crashed during departure in Ethiopia

This 'buried in the dirt' has me wondering how they found the Boxes so quickly.. Oh wait, they're now in the tail aren't they?

Keith Cress
kcress - http://www.flaminsystems.com

RE: Another 737 max has crashed during departure in Ethiopia

The Stab trim cutout switches are inline one is a backup in case the first one fails closed. flipping one should still cut power to the motor but for safety sake it's a redundant pair that gets flipped at the same time. In the closed position it has protection from being moved to cutout accidentally. Once moved to Cutout all electric trim is lost, pilots can only manually trim the plane. The pilots electric trim on the stick stops MCAS for 5 seconds after release before it re-initiates trimming (runaway trim is apparently different in that the pilots electric trim switch does nothing to stop it and can be up or down). MCAS can not turn itself back on after stab trim cutout switches are moved to cutout, only after being stopped momentarily by the pilots trim switch(5s before reactivation).

I think from pictures of the crash site it is clear it was a high speed nose down crash, and that rules out any mid air explosion or engine failure. There is a very concentrated debris field around the crater, not a large extended debris field cover kilometers before the crash. Any sort of mid air explosion the was significant enough to cause a high speed nose down crash would have left a secondary debris field.

The FDR and CVR data can not come out soon enough but I will wait patiently.

RE: Another 737 max has crashed during departure in Ethiopia

I am still struggling with the purpose of the MCAS.

Quote (As stated on the b737.org.uk page)

This new location and size of the nacelle causes it to produce lift at high AoA; as the nacelle is ahead of the CofG this causes a pitch-up effect which could in turn further increase the AoA and send the aircraft closer towards the stall. MCAS was therefore introduced to give an automatic nose down stabilizer input during steep turns with elevated load factors (high AoA) and during flaps up flight at airspeeds approaching stall.

What I get from that is the MCAS is most active during take-off and climb-out (the times of both crashes). It should be inert and/or remove all compensation during cruise and descent for landing. Right so far?

Also, there seems to be a variable lift-curve on the nacelle body, possibly energized by the intake's airflow. What doesn't pass into the nacelle is accelerated before passing over the nacelle body, generating lift on that surface. Takeoff and climb are the high-power phases of flight, too, so the acceleration would be greatest.
One more thing: none of the descriptions of the MCAS system refer to an engine power as an input value, just AoA airspeed and altitude.

Quote (b737.org.uk)

The MCAS function becomes active when the airplane Angle of Attack exceeds a threshold based on airspeed and altitude.

Lion Air crashed into the ocean (alitude=0) and Addis Ababa is at 7,700 feet so we have a wide spread of altitude inputs with the same result.
What is common in both crash events is that the airspeed and angle of attack were all over the place.

Would it help if we thought in terms of a PID controller that is not properly tuned, leading to an overshoot? The literature (in the media; I haven't been able to read Boeing's data) says that the rate is 2.7 (correction: 0.27) degrees per second. So there's no way to tune the rate to keep up with more rapid pilot inputs or gusts? Making it not even a "P" controller (Proportional)?
Or is this a wrong-headed way of thinking about this system's function?

<edited to fix an incorrect number, thank you LH>
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Another 737 max has crashed during departure in Ethiopia

LittleInch and MDEAus; Thanks for the clarification.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Rumours are going around that they found the elevator screw Jack and it was in the fully nose pitch down position.

RE: Another 737 max has crashed during departure in Ethiopia

Oh,

The thing I haven't figured out is what happened apparently at the end of the Lion air flight, i.e. it bounces around seemingly between the application of the MCAS and recovery in a cycle of several seconds and then after some time it just dives near vertical.

Does the MCAS gradually increase the max trim angle?
Does it allow a certain number of cycles and then go beserk and just goes max nose down?
If you don't pull the elevator trim back to level does it go a second time after a few seconds for another attempt at nose down until it runs out of elevator trim?

Sparweb, from what I've heard the trim control goes at a certain increase angle per second to a max of 2.7 degrees after I think 9 seconds.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
There really isn't much official out there about the system or how it works. There is absolutely zero about it in the pilots training for it.

Apparently the difference training is 2 hours of CBT then go fly the plane according to Boeing.

RE: Another 737 max has crashed during departure in Ethiopia

I'm just wondering if they ever really software tested it for multiple operations of operating followed by reset followed by... Strange things happen sometimes if the program decides enough is enough and just goes full pitch down.

Rereading the info in the posts above, it looks like the system continues to go nose down if it thinks the previous adjustment hasn't worked and one issue which is impacting the roll out of the mods is whether and how much to limit the max elevator trim.

for Boeing to not release the software update for months after it has become clear it had a large part in the Lion air crash tells you that there is something not right in how this MCAS works under real life situations and bad data.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Apparently the government shutdown screwed the FAA up somewhat.

RE: Another 737 max has crashed during departure in Ethiopia

Quote (IRstuff)

And, they ['Black Boxes'] beep.

Traditionally, the smaller (~ 4-inch) Underwater Acoustic Beacons (UABs) attached to the Black Boxes beeped at ultrasonic frequencies. E.g. The very common now-obsolete DK100, or its newer replacement DK120/90, both ping at 37.5 kHz. One may still hear a faint click, if it's still working.

There are now also 8.8 kHz LF UABs, but they're longer (~ 6-inch) and are generally designed to be attached to the fuselage itself. They're more recent, perhaps starting circa 2012 as far as I can tell.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Those black boxes are going to be mangled and burnt to a crisp that's why they have to be sent to France.

All the outside of it will be junk and the connectors unusable.

They have to take the solid state memory out of it and remount it to a reading board then download.

RE: Another 737 max has crashed during departure in Ethiopia

Sparweb - I already posted it, but I'll do it again for everyone's benefit since what seems to be the wrong info keeps being repeated. It changes at 0.27 degrees per second. The limit is 2.5 degrees of change which would occur over 9.26 seconds.

From the descriptions, the MCAS will apply a trim correction up to 2.5 degrees. It then does it again 5 seconds later if it still believes the plane is close to a stall condition.

The electric trim switch on the stick will control the trim, which means it can over-rides MCAS if the pilot uses it to command trim up. However, the pilot can't hold it or else the plane will stall. So, they have to release it and then the MCAS will start to command trim down again.

From the manual page at the previously linked site, it says for trim, flaps up the stabilizer can change at 0.2 units per second and with flaps not up the stabilizer can change at 0.4 units per second. MCAS is only active with the flaps up. So, what is a unit? Is it possible the MCAS can move the trim faster than the pilots can via the trim switch?

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
The round bit is where the solid state memory lives. The mangled bit is the connectors, pinger, transmitter.

RE: Another 737 max has crashed during departure in Ethiopia

Quote (thebard3)

I have a hard time blaming the aircraft design although it seems the MCAS was perhaps a contributor.

I agree. It may well turn out that manufacturing or maintenance problems contributed. And it will be a chilling find if it is determined that there was something simple the pilots could have done.

I wonder what is the maximum speed that you can deploy flaps. Maybe someone knows if this would disabled the automatic trim system.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
It would disable it.

Flap speeds is 230 knts I think for the 737 for the first stage.


The MCAS system is to add stability to the control pressure. I belive that the control responce is not linear ie we usually have increasing control forces as you get nearer the stall to pitch the nose higher.

Due to the nacelles on the leap engines thay start developing liftat high angles of attack and that means the control forces to increase pitch become less the closer you get to the critical angle of attack which is against crtification rules. So they added in theis automatic trim nose down fuction to increase the stabity in pitch while manual flying. I think its only really meant for the go around situation.


The action of it isn;t just one cycle and then stop at 2.5 degrees it pauses and the system rests then does it again and repeats until the AoA reduces or the autopilot gets engaged.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)


Here is the mechanical side of the system for those interested

RE: Another 737 max has crashed during departure in Ethiopia

The 737 was designed in the 1960's. What have you still got running that was designed in the 60s? My toothbrush? Not even. The 757 and 767 were developed decades later than the 737 and both of them have been retired. 737 Max? More like a 737MF (MaxFrankenstein). I suspect that design modifications to the 50+ year old airframe have finally caused inherently unstable flight within certain areas of the performance envelope required to conduct normal operational manuevers. Now some obviously low IQ, AI software was patched in as a vain attempt to keep the aircraft from entering attitudes that have been found to provoke the resultant situational aerodynamic instabilities and it may think it is smarter than the PIC. And that may be right, given the lack of speed and clarity of the "work arounds" issued to pilots by Boeing itself, which may or may not work. Whao! When Boeing (or anybody) starts thinking that hastily written AI software (did it even make ver 1 yet?) is the best possible method to correct bad aerodynamics, I'm bailing out literally! What the heck are they thinking... all this is some FlightSim game? Take your eyes off the turn and bank indicator and look out the window once in awhile.

My humble advice is don't fly a Max until the airframe is substantially corrected. I doubt that will ever happen, given the certification costs and time schedules involved in that. Leave unstable flight envelopes to bees and helicopters.

BTW, waiting for more data before grounding the MaxF was not my idea of a risk adverse industry and ... who trusts any branch of USA.gov to make a responsible decision these days? 50 other countries being first shows how much evidence there is for that.

RE: Another 737 max has crashed during departure in Ethiopia

The Seattle Times report posted by BrianPetersen is chilling.

Am I the only one to interpret

(1) The certification authority FAA has partially or substantially delegated the safety assessment authority to the manufacturer Boeing.
(2) A design change of 400% on the limit of the tail rotation angle, from 0.25 to 2.5 degree, was implemented "after" the 737 Max8 was certified its airworthiness.
(3) The design of the MCAS can allows unlimited self-activation, possibly at the maximum permitted tail rotation, over the pilot's intervention.
(4) Both FAA and Boeing were aware of the first three issues and did nothing even before the second plane crash occurred in Ethiopia.

I can understand in (1) this is possibly a common practice in view of Boeing's expertise and FAA's lack of resources and (2) The subsequent flight tests could demand a large increase of the tail rotation to make the 737 Max8 work. However if the rumour that the recovered jackscrew, which pushes the horizontal stabilizer up and down to rotate the tail in Alistait_Heaton's supplied diagram, were true in the Ethiopian plane then the MCAS could have played a major role in bringing down both planes?

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Yes both screw jacks have been found and both were at maximum travel to pitch the nose down.

RE: Another 737 max has crashed during departure in Ethiopia

A few years ago, I was working at a large heavy oil plant. This was a rebuild following a fire and the plant was down to 50% production.
Gross revenue was down over $10,000,000 a day.
In the wake of several serious safety violations by one contractor, the contractor was removed from site and another contractor brought in.
Note that there were no deaths, injuries or equipment damage. It was a case of workers being directed to do unsafe work.
The crew was allowed to remain and was directed by the incoming contractor.
Basically, all management personal were removed.
Crew foremen, who relay instructions but do not effectively have decision making authority were allowed to stay.
All management with decision making authority were removed from site.
I wonder if there will be a similar top down purge at the FAA.
That would send a strong message for a generation or so.
Does my post sound a little harsh?
187 deaths due to pressure to meet deadlines.
That's harsh.
Four months later another 157 deaths.
That's a little more than harsh.
Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

I saw an air crash investigation of the TAM Fokker 100 that crashed in Brasil in 1996, something struck me as similar. A safety system that pilots were not trained on functioning in an unexpected way during take off. On the Fokker 100 it was a safety to reduce power to an engine if the thrust reversers deployed during flight, pilots at TAM weren't aware of that function so they fought the reduction in power as there was no warning of thrust reversers being deployed. On the 737max the MCAS system is meant to keep the aircraft in the flight envelop yet the pilots were not aware of a system and the way it functioned (granted every max pilot should have after the lion air accident).

Is there a readout somewhere of what angle trim settings are at during flight available to the pilot and FO? The manual trim would be spinning which should be a key to the pilots decision but if they think they've countered it with the electric trim switch but haven't fully countered it (1.5 degrees up every time MCAS commands degrees nose down), what in the cabin (apart from looking out the window) would shout that the trim has reached maximum nose down trim (even before the aircraft is pointing nose down)?

Would an augmentation system meant to make it feel like flying the NG really need to access the full stroke of trim? Is there even position monitoring of the trim ram that is fed into the FCCs?

RE: Another 737 max has crashed during departure in Ethiopia

Saikee,

I tend to agree with you.

The key issues coming out seem to be the significant change in max angle from 0.6 to 2.5 degrees and the clear lack of understanding that this system refuses to die after effectively being cancelled and also keeps increasing the trim until it can't increase it anymore. For it to work "in the background" and not advertise itself in any form as a light, warning buzzer or similar is clearly key also in terms of pilots not understanding what is going on with probably a host of other alarms and errors popping up all over the panel.

The desire to both get a certification and also make the system appear identical to earlier versions is the thought process which goes wrong as well as only using a single sensor and not recycling the decision when the parameters change implies a lack of frozen design or poor Management of change procedures.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
There is usually a trim indicator which needs set for a CoG position prior to departure. If it s not set within a certain range a config warning sounds when the aircraft thinks your about to go flying. If you get it wrong it may mean that you can't lift the nose off the deck if its trimmed to far forward or if its to far rearward the plane will start to pitch nose up before you get to rotation speed which may cause a tail scrape.

If the aircraft thinks its stalling there are multiple alarms both tactile,visual and audio, The stick has a vibrator on it which shakes it which creates quite a loud noise, there will be main caution light flashing and also a indicator which side of the aircraft is about to stall. There are three modes normal flight with nothing going. incipient stall with caution lights and stick shaker. Then full stall which is the master caution and a stick push which shoves the nose down in types which can develop into deep stall. There are links to the rad alt with cut offs of the stick push to prevent the nose getting shoved down in the last x amount of feet before landing which varies with type.

The stall system going off is extremely attention getting. The flight deck will be extremely alive with multiple warnings going off, it would be pretty easy in my opinion to miss the trim wheel moving un-commanded.

RE: Another 737 max has crashed during departure in Ethiopia

Alistair_Heaton is on target, from my perspective. On the ground with the pilot reading a manual or using CBT for familiarization, it is easy to understand, "If the trim appears to be arguing with the intent of the pilot, use the STAB TRIM CUTOUT switches." But takeoff is already well known among pilots as a high workload phase of flight with plenty of factors capable of killing you. As such, taking the wrong action during takeoff can be as bad or worse than doing nothing. So as Alistair indicated, recognition is vital, and recognition during a very busy flight phase is difficult. Also as Alistair noted, the trim wheel and indicators are well down out of the line of sight unless the pilot takes their eyes off of the outside horizon or the control instruments, whichever is being used to establish their situational awareness.

Using the Lion Air preliminary report from the authorities, the Lion Air accident aircraft had the same activation of the MCAS during the flight just the day before. While maintenance cleared the issue by following the manual, apparently the true fault was not corrected. The accident flight crew would have had the aircraft log available for review, but there is no way to tell if the wording of the log communicated to the accident crew the true circumstances, and most importantly, the actions taken by the previous crew which resolved the trim runaway and allowed for continued safe flight. It is unlikely that the two flight crews had the opportunity to speak directly to each other.

So for a recap (admittedly abridged) and an application to the Ethiopian accident:

1. STAB TRIM CUTOUT switches to stop any type of runaway trim have been available on the flight deck of commercial aircraft for decades. Trim runaway would be defined approximately as, "The trim is moving when it should not be moving, or is moving in a direction it should not be moving." It does not matter if the MCAS is moving it, or some other system failure is the root cause. At that point a typical pilot would not care about the root cause, they just want to stop the runaway. Thus, STAB TRIM CUTOUT switches exist. Pilots likely have an "official" definition that is better than mine of trim runaway - but I think I am reasonably close.

2. IF (and this is the big IF) the Lion Air accident crew and the Ethiopian accident aircrew recognized trim runaway then they should have already been trained, as aircrews have for decades, to use the STAB TRIM CUTOUT switches.

With all of the above being said, unless they were unaware of the Lion Air crash with trim runaway as the preliminary target of the investigation, it is difficult to understand why the Ethiopian flight crew did not actuate the STAB TRIM CUTOUT switches.

RE: Another 737 max has crashed during departure in Ethiopia

The airframe problems with newer aircraft or should I say the flight controls, were essentially a non issue in the older days of aircraft. The main problem is electronics and computers, the lack of manual systems like the days of control cables, and using a motorized or servoized jack screw to pitch the tail plane or horizontal stabilizer. DC-3's and DC-7's and other such aircraft used a controllable trim tab, not the whole tail plane, just like a small aircraft and if for some reason it got stuck the pilot could still over ride the effect. I am thinking even if with this max 8 situation, if the pilot knew what to do to prevent the dive into the ground the flight control system would very likely not allow him to do the required maneuver.
The fix for the dive would have been to invert the plane, scary yes, but still better than diving into the ground.

The main question is: How come even with full nose down tail plane the controls ie the elevator could not over come and counter that effect?
My guess is, the flight control system won't allow it. There is always a simple solution to problems like this. Back to the good old system, control cables and fixed tail planes.

RE: Another 737 max has crashed during departure in Ethiopia

If that's the case, its a crappy control scheme in a life or death application. To me that's not a good instance of "back in the good ole days things were simpler", it's just an overall poor design.

RE: Another 737 max has crashed during departure in Ethiopia

I may be inaccurate in detail, but qualitatively speaking, the last two large aircraft, (AFAIK, maybe there were other contemporaries, e.g. from Tupolev), that had unpowered main controls or full manual reversion in the event of power assist failure, were the Bristol Britannia and the original Boeing 707. These concepts did not persist into succeeding generations of large aircraft, as they had their own drawbacks, I suppose, high control effort possibly being one, and lack of direct linkage (i.e. servo controls) being another. Hence the introduction and eventual ubiquity of fully powered main controls on large aircraft.
In general, the large aircraft manufacturers seem to have gotten it right from the late fifties until recently.
I remember the 737 (or was it DC-9?) had some kind of mechanical issue with the elevator jack, several decades ago, but that was a design or material issue, not a conceptual issue, IIRC.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Another 737 max has crashed during departure in Ethiopia

Not sure this adds a ton to the discussion. But, for the folks who don't know much about jet planes and such, Juan Brown's channel on YouTube (blancolirio) has some good discussion about these 737 crashes. Juan is a commercial airline pilot (777) here in the US and came to my attention with some good reporting on the Oroville Dam spillway issue and construction.

https://www.youtube.com/user/blancolirio/videos

RE: Another 737 max has crashed during departure in Ethiopia

I am wondering how those AoA sensors ever got approved.
Not a very good MTBF (Mean Time Before Failure)
And not a very good MTBF (Mean Time Between Fatalities).
The first delivery was a MAX 8 on May 6, 2017,
Second crash was on Mar 10, 2019
That's 344 fatalities in 673 days.
Even factoring in the 350 Max 8s flying it is not good numbers.
Then add in the several failures of the AoA sensor that did not result in a crash.
Are these sensors new to this aircraft? If they are used without problems on other planes, why are they failing on the Max *.

Anecdote. A friend of my wife's was visiting today.
I overheard her mention to my wife that she had phoned WestJet concerning her upcoming Mexican holiday.
She wanted to be reassured that she would not be flying on a Boeing plane.
In the end the market place may deliver the harshest punishment to Boeing.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

Thank you Alistar,

Is it possible that MCAS is triggering before any stall warnings are active? I know we are limited on the knowledge of MCAS system but if it is activating only from AoA input (lion air had faulty input for some reason), What does the FCC use to determine stall? Lion air had the stick shaker active the whole flight from memory so they must have been dealing with false stall warnings.

The MCAS system could have been employed effectively to simulate the handling of the NG aircraft. From my perspective MCAS should have greatly limited authority, and a limited range (50% of nose down trim or whatever is counter-able with stick pressure to keep the aircraft level).

This whole situation to me boils down to
  • An underestimation of the risk associated with the MCAS system (which may have been fine if it was limited to 0.6 degrees per activation or been prevented from driving the stabilizer to full nose down)
  • Uninhibited authority off the MCAS system leading it to command trim inputs (requiring pilots to counter it and ensure they've arrived back at the correct trim setting)
  • Reliance on a procedure for runaway stabilizer (can present much different symptoms?)
  • Reliance on only (one) AoA input for MCAS activation
  • Pilot confusion over strange symptoms (poor documentation and training)
There may have been things that the pilots could have done to save the flights (see previous flight of lion air) but a system like this should never have been approved. Another thing that annoys me with the MCAS is that it's to simulate the NG 'feel' during high AoA maneuvers yet it's supposed to only trim nose down, so after any high AoA maneuver ( yeah take off is probably it in a normal flight) Trim needs to be reset by the pilot to what they would consider normal. I'm guessing this is something that MAX pilots must have experienced and noted that it is different to the NG? If not is it safe to say that MCAS isn't actually required or could be significantly limited to low levels of trim adjustment? As normal operations wouldn't normally see it activate and higher AoA conditions should still be within the flight envelop otherwise this would instead be a stall protection system which I'd assume would have a greater risk profile.

RE: Another 737 max has crashed during departure in Ethiopia

debodine - You bring up a point that has made me wonder if there is a bigger issue that has remained hidden. I would have expected the pilots to know to throw the trim cutout switches when experiencing runaway trim. So, I'm finding it difficult to explain why they struggled for minutes counteracting runaway trim without throwing the switches.

enginesrus - In this case, Turning the trim cutout switches to the off position and then using the manual trim wheel instead solves the problem. So, the solution is to revert to manual controls, just like you want.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
I only have access to the same info as you how the MCAS system works... Which is the same as the pilots who were flying them.

Just some points through about flight controls.

I have flown unpowered controlled aircraft the Jetstream 31/32 and 41 the 41 is a 10 ton aircraft. They are firm and relatively slow response and you get a good work out on a high wind approach. When you move to bigger aircraft the control response is approximately the same weight but the forces involved normally are the same. this is done via what's called a feel unit which applies a force to the controls which varies with the airspeed. If you say have a hydraulic failure its a whole different ball game your talking two feet braced against the panel and pulling with both hands to move the elevator backwards to flare to land.

FBW is a different ball game which i have zero experence with outside flying a Airbus sim a couple of times. I don't want to comment about it. Mates that have flown them say the first 3-4 sessions in the sim are a bit wierd but you get used to it and after that it no problme but its a different way of thinking.

Now the reason why they had to have the MCAS system. The leap engines are extremely effecient. We had 737 classics fleet and also CS300 fleet the CS fleet uses 1600kg of fuel an hour the 737's its 2400 kg an hour. The fuel savings are collosal. The leap engines are a geared fan and the fans are huge. This means the engine pod is huge. So when they fitted them to the NG wing they didn;t have enough ground clearance. SO they raised the gear height and to get more room the moved them forward and up.

737 800



737 max 8






RE: Another 737 max has crashed during departure in Ethiopia

4
(OP)
now if you look at the shots above its pretty obvious the geometry changes that have needed to be done.

The leading lip of the nacelles if significantly forward of the leading edge of the wing on the max.

Now what's apparently happening is when the aircraft gets into high angles of attack the huge pods which have a flat base are generating lift and because they are so far forward of the centre of lift of the main wing they are forming a moment couple in addition to the elevator. This has the effect that as the angle of attack increases the control force decreases as does the stability. This is completely against certification rules. As you get closer to the stall the control forces should increase and the stability increase with the aircraft having a natural inclination to lower the nose to decrease the angle of attack. In all cases in the event of a stall in straight and level flight if the pilot lets go of the controls the planes stability should mean that it self recovers ie the nose drops and the angle of attack is reduced.


This wasn't the case with the max with those engines. So they stuck a computer fix in that altered the trimming of the aircraft to produce forward trim as the angle of attack increased. That in itself I don't have a problem with really. What they didn't do is then complete the risk matrix to look at how the Angle of Attack is measured and the failure modes. We tend to have three of everything for critical systems.


Take Hydraulics for example: we have a separate system powered by each engine with either a backup electrical pump or a PTU from the other system or both they are powered from the main electrical buses with pumps fitted to the ancillary gear box . We also have an emergency system which is completely separate which is powered by a DC pump off the emergency battery bus and on these big jets that will be linked to the ram air turbine which is a little windmill that pops out the side of the plane in the event of power failure of both engines electrical supplies (again 3 systems) it has an accumulator and the pump charges it so you have enough pitch authority to flare to land.

The MCAS took its input from 1 AoA sensor of which there are only two fitted so no way of determining the odd one out in the event of a failure. No comparison indicator warning on the flight deck as standard between the two sensors. All other critical flight instruments again follow the rule of three. And all the rest will trigger comparator warnings if there is conflict in the readings, then the pilots can look at the separate system and two out of three win and the faulty reading can be deselected.

Realistically I can't see a fix for the engine lift issue without a complete redesign of the wing and aircraft geometry.

The instrumentation the minimum I can see is them having to fit a third AoA vane. With that it requires a huge rethink of the avionics software. The retrofitting a 3rd vane will not be easy either.

After that pilot training needs to be revisited and there needs to be more than just a 2 hour CBT. And simulators need to programmed for the MAX currently there is only one in Seattle everyone else does their 6 monthly training on NG 737-800 sims which I believe have MAX performance programmed into them getting rolled out but don't have the MCAS system simulated.


Realistically the safest option is to kill the grandfather approvals based on old type approvals. But that would significantly increase the costs of new types in the same product lines.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
To note flying an transport cat of aircraft inverted is an extreme solution. As pilots we are not trained to do it. The systems are not designed to operate under prolonged negative G. They are not tested to do it.


For them to be able to do it then the complete interior of the aircraft would need to be redesigned for negative loads the additional metal required for the seats alone would put so much mass onto the airframe it would be uneconomical.


The aircrat should not be designed in such a way that its required.



RE: Another 737 max has crashed during departure in Ethiopia

Why can the trim greatly exceed the elevator control on a computer controlled flight system?

Answer: So the government can take over the plane and plant-it from the ground if needed. [/conspiracy theory]

Keith Cress
kcress - http://www.flaminsystems.com

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Oh lord is that the nonsense that they are coming out with now?

Its bad enough when you get a flat earth or chemtrail nutter on board.

The flat earth sit with a spirt level in flight filming it with their cameras.

And the chemtrail lot try and take samples of everything including the crap that comes out the drain valves at the bottom of the fuselage onto the ground. which is the accumulation of sweat and breath moisture which condenses on the inside of the hull in cruise and then melts and runs down to the bottom and drains out the spring valves when the plane is not pressurised.

I was flying an aircraft with a water meth boost kit for hot high operations. The tank was visible in the rear hold when pax were boarding. I thought one guy was having a sexual experience in his pants walking up the steps trying to get pictures of it.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)


This apparently what it does to the stability

RE: Another 737 max has crashed during departure in Ethiopia

Yeah, that was insisted at me by an engineer.

BTW: Juan Brown put up a pretty informative vid on the trim equipment showing it running.
YouTube 737 MCAS

Keith Cress
kcress - http://www.flaminsystems.com

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
first words that entered my head when I read your post was "software...applemac"

RE: Another 737 max has crashed during departure in Ethiopia

Alistair,

A great explanation as usual.

It seems to me that Boeing are not in a good place with this design and explains why there was no quick fix following the lion air crash.

In order to follow the certification rules and prevent a runaway stall they need to modify the flight controls and their only means seemingly is to actually alter the flight control surfaces and not the flight controls.

To do this though using only one of two AoA sensors and then having to increase the action from 0.6 degrees to 2.5 degrees has been disastrous. Sure - there are ways to prevent this leading to destruction but it is clear that with all hell breaking loose in the cockpit, stick shaking, alarms, the plane seemingly having a mind of its own and one or two quite hard to get to switches a procedure built approach to a sensor or computer fault isn't working. This (the MCAS system kicking in) was not the only thing going on and both planes apparently had to deal with faulty or discrepancy in sensors which could easily lead to confusion as to what was happening.

I don't see any easy way out which will allow a quick return to operation and keep within the rules of certification. Fix one problem and create two more.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Also I am being told that this idea you can use the trim cut offs is a bit simplistic.

Yes you can shut them off.... but and its a big one.

The manual trim unpowered requires a handle to be folded out from the trim wheel. Then the thing wound for minutes to get it back from the full pitch forward position to something nearing what you actually need and its relatively easy to still control the aircraft.


I am reliably told by the classic pilots at work even if pre prepared for it, the FO built like a grinder on a volvo ocean race crew your going to loose an min of 6000ft until its sorted. Normal people who aren't pissing about in the sim its more likely 10 000ft.

RE: Another 737 max has crashed during departure in Ethiopia

Man itsmoked, I was really hoping you were just kidding. That's depressing.

RE: Another 737 max has crashed during departure in Ethiopia

Alistair - Man that is not good.

I thought it might take longer clearly if there is no electric power, but 6, to 10,000 ft....
So unless you manage to hit the off switch just after you've manually thumbed the trim switch back to near level then you're done for at low altitude??

I saw somewhere that the final nose down on Lion air was because the FO only flicked the trim switch up instead of holding it up to regain trim back to near level and then the MCAS kicked in again.

It seems as though the manual trim up switch on the yoke doesn't work while the MCAS is busy winding it down. Can anyone confirm this?

Maybe the same happened on ET with a low hours FO taking over while the captain tried to work out what was going on.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Your pretty much done with most control issues at low altitude.

Which is why we tend to head upwards like a fart in the bath to give us room and potential energy to deal with things.

The electric trim switch should kill the MCAS system for a period of time. Then it resets and does its thing again. Sorting out what's actually going on with all the bells and whistles going off is shall we say intense.


Another thing is that if the stick shaker is triggered that usually kicks the auto pilot out. And as soon as the auto pilot is out the MCAS system kicks in if the flaps are up.

RE: Another 737 max has crashed during departure in Ethiopia

A friend clued me into reporting by Dominic Gates, long-time-all-things-Boeing reporter for the Seattle Times...

Flawed analysis, failed oversight: How Boeing, FAA certified the suspect 737 MAX flight control system
https://www.seattletimes.com/business/boeing-aeros...

Reporter told Boeing, FAA of possible safety issues with 737 Max four days before fatal plane crash
https://www.philly.com/news/nation-world/boeing-ma...

Also, 'Sully' Sullenberger had s some words of concern regarding Boeing and the flight crew... specifically the 200-Hr total time copilot...
Captain Sully Weighs In On Boeing 737 MAX Crash
https://liveandletsfly.boardingarea.com/2019/03/16...

There have been several incidents of runaway/uncontrolled stabilizer-trim systems causing mishaps... some caused by jack-screw-stripping failures due to maintenance... some due to inadvertent trim actuation by non-pilots in the pilot's seat [yes-gag-for-real] and these... 737-Max that [at time] appear related to flight control software 'bugs'. Hmmmm... maybe this is why Southwest Airlines maintenance was being fined by FAA for poor practices regarding weight and balance calculations?!

The term 'sneak circuit' applies whenever circuit-designs create unintended electrical/electronic pathways. There appears to be an equivalent concept for computer code... 'sneak-computer-code' or 'sneak-software-code' is very real... leading to unintended consequences if not fully/completely vetted by simulations and flight testing. This 'sneak-software-code' is relevant to aviation as it has been to space exploration.

NOTE. At-least-two-possibly-three Mars orbiters/landers have encountered catastrophic software bugs... and of course there was [quietly covered-over] software bug for the Huygens-probe that landed on Saturn's moon Titan.

NOTE. RE the Huygens probe... the highly calibrated/sensitive transmitter [for precision Doppler tracking on atmospheric entry and parachute descent]... and which was connected to certain sensors and a second landing camera system... was turned-on in 'stand-by mode' to warm-up... but the computer code sequence failed to include a 'turn-on the transmitter and send-data' command-line... so all of that channel-data was 'lost'. Good-thing that the non-precision transmitter worked 'well-enough' to send good quality images/sensor-data and good-enough signal data for Doppler tracking/images.

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
I will admit I fly with 200 hour fresh meat in the cockpit. And I also fly with 1500 hour fresh meat in the cockpit.... To be honest they are both clueless until they get a couple of 100 sectors under their belts sector length doesn't change things. This whole hours as a gauge is utter bollocks. I have 8.5k hours with an average sector length of 1 hour. A mate that went heavy early but qualified at the same time has 9000 hours with an average sector length of 5.5 hours. Giving him 950 landings when he has been at the controls. I have way over 4000 landings in commercial aircraft who is the most experienced? Mind you he is still a first officer and I have been a Captain for some 12 years now. I fly regional turbo prop short haul.

If you stick a pilot with 2000 hours single pilot single engine into a multi crew transport aircraft they are in the same state as a 200 hour out of school pilot. They both need 150-200 sectors before they know what they are doing. And there is only way they are going to get that experience.. Fly with bald grumpy moaning bastards like me. Don't worry I do try and fill there heads with the reason why we do things the way we do and it not because I said so.

Lets face it... its exactly the same with baby engineers...

RE: Another 737 max has crashed during departure in Ethiopia

Alistair_Heaton ... don't recall hearing Your name... but interesting/valuable comments...

"Lets face it... its exactly the same with baby engineers..." .... SOOOOOO TRUE!

My dad was a fighter pilot and long-time GA pilot... He always expressed doubt at how much time-experience a bomber or transport pilot and copilot should actually record... especially when they had the luxury to eat or drink and leave their seats to go to the head... etc.

A couple of favorite quotes comes to mind...

"Flying is long hours of boredom, punctuated by moments of stark terror." [paraphrased, W Churchill]

"Experience is a cruel teacher. First she gives you the test; then she teaches you the lesson.” [often cited version of Vern Law’s quote]

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Fast jet ex mil have other issues in commercial transport. Some of them get over them and are a pleasure to work with/for. And others are a danger to themselves and others.

But that's not really significant to this thread or the problems with the MAX.

But it does highlight the liveware aspect to most issues in aviation. Its how the operator interacts with the hardware especially when it goes wrong that is crucial.

RE: Another 737 max has crashed during departure in Ethiopia

Haven't seen any mention of this: https://abcnews.go.com/US/wireStory/pilots-reporte...

A couple of incidents where the 737 Max nosed down after engagement of autopilot.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
I wouldn't put to much into them because they didn't go through the full investigation process and were only pilot reports.

The problem with pilots reports is in the heat of the moment our memory's are not very good because our bodies are putting all the resources into reacting. We all experience this in sim debriefs the TRE starts going on about something that happened 4 hours ago and you really can't remember what you did after the session. Which is why the more progressive company's video them and we can watch them in the de brief and they are then deleted in front of us.


Here is a similar nose down incident on my type...... was it a problem with the aircraft... Was it hell.

https://assets.publishing.service.gov.uk/media/5bc...

Unless the FDR is pulled and they run it through the variable machine nobody has a clue what was going on. BTW in my area of the world all our flight data is pulled for every flight for set of variables. And it has to go through a quality process to ensure we are not flying like cowboys. But that data doesn't have the same number of variables as the FDR.

RE: Another 737 max has crashed during departure in Ethiopia

I am wondering about the initial trigger.
Why are those AoA sensors failing so frequently?
Are they a new type used only on the Max8?
Is it a problem with the mounting location?

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

Aside from the Lion Air flight which had documented maintenance issues, I don't think it's confirmed the sensors are failing (or is it?)

RE: Another 737 max has crashed during departure in Ethiopia

Don't forget it could be purely a SW problem too. With complex systems people often scream hardware when it's actually software.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Another 737 max has crashed during departure in Ethiopia

Quote (AH)

It's how the operator interacts with the hardware especially when it goes wrong that is crucial.

KC beat me to it.

I was going to mention that you spelled "software" incorrectly. winky smile

The design decisions made in this example will become 'poster children', or case studies. Both hardware and software. And certification.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Sorry the way I was using the term is in relation to the shell human factors model.

https://en.m.wikipedia.org/wiki/SHELL_model

When you live and breathe this stuff its easy to forget that people might not know.


RE: Another 737 max has crashed during departure in Ethiopia

In current developments, there seems to be some troubling logic.

First
The rudder increment of 2.5 deg shall be reduced back to something alike the original .6 deg, but: it has has been altered for a reason! As is it said that it became necessary during testing, for stall protection, this runs in a circle. Meaning: You'll not have the needed feature in that other flight situation, as .6 deg increment has been proven to be too low then.

Second
If MCAS is, say, mimicking a well known flight behavior of a previous model range, you can't just switch off auto during an emergency, because then you'll meet someone new: The airplane flying AS IT IS, with its flight characteristics of an elder airframe coupled with superfar forward big size modern powerplants.
Mr. Sullenberger is correct to require two qualified pilots in the cockpit, but these pilots should be able to fly two planes at the same time, them being just the flip of a switch away from each other. This seems to be high end professionalism i can't fathom to be standard all over the world.
Correct me if I'm wrong.

Third:
The second AoA sensor shall be wired in. But then: As it has not been done until now, again there might be a reason. Boeing will not have been building in two sensors and then leave one out off for decoration. If, for whatever reason, they could not make those AoA-sensors synchronize, or the coupled sensors output is so prone to failure or mismatch or whatever, the improvement might again lead to systemic failure.

This reminds the Space Shuttle story all over again. So they, they had to learn the hard way to ask: What, if there's still more to it?

The Max planes, if made airworthy again by FAA in April, shall be on a continuous trial run.
But who will trust FAA now? They don't have the know-how, they don't have the manpower, they are not independent, they don't know the plane and they don't speak up when it matters.

Finally, there's people on board. My daughter, your wife, a beloved one.. anyone!
Talk shareholder value now.
And that so many dead people do not make open any mouth with a face to it from within Boeing engineering, let alone the company as a whole, this troubles deeply.
Flying with a plane, that's about trust, in engineering, and certification.

Roland Heilmann

RE: Another 737 max has crashed during departure in Ethiopia

It's all about trust and the trust is gone;
I first posted this in the other 737 thread by mistake.
Boeing 737 MAX to face first congressional hearing Link
Europe and Canada Just Signaled They Don't Trust the FAA's Investigation of the Boeing 737 MAX Link

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

Quote (Alistair Heaton)

The poo is getting more intense for Boeing
From the article:
The FBI’s support role was described by people on condition of anonymity because of the confidential nature of the investigation.
The papers always have an anonymous source to quote.
Congress has to get involved, because well, that's what they do.
My money says no criminal charges will ever be filed. Boeing will pay some meager fine and one of the world's most popular and safest aircraft's reputation will be besmirched forever.

Brad Waybright

It's all okay as long as it's okay.

RE: Another 737 max has crashed during departure in Ethiopia

ROIMEC,

I think you've got it correct.

That's why Boeing didn't rush out a simple "software fix" because when they looked at it closely and, maybe, reran the safety review and analysis with the data they now have and are using, they realized that it didn't work.

To maintain the classification rating they need MCAS.
A faulty MCAS is now, most definitely in the catastrophic rating for safety
Therefore the input sensors now need to be at least one order if not two order of magnitude more "reliable" and able to self diagnose and take the correct reading before activating as it needs to and ONLY when it needs to, not spuriously.

How the pilot can override it to again not prevent it operating when it should becomes very tricky. Make it too easy and you could get planes stalling when they shouldn't - equally bad news.

I don't envy them.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Another 737 max has crashed during departure in Ethiopia

"My money says no criminal charges will ever be filed. Boeing will pay some meager fine and one of the world's most popular and safest aircraft's reputation will be besmirched forever."

Add that to the points RolMec made, and it adds up to another 737 Max 8 crashing.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Well safest apart from the hard over rudder issue. Which they only really sorted in 2005 world wide.

But your right it is a sad note to end an aircraft line. Can't see anyone touching them now. The punters just won't want to fly in them

RE: Another 737 max has crashed during departure in Ethiopia

This is growing beyond just Boeing.
With the FAA reportedly losing credibility worldwide, this issue now may have a devastating effect on the entire US aviation industry.
If the foreign regulators require the Max 8 to be certified as a new plane, it may be the end of the Max 8.
Even if foreign regulators accept the Max 8 as a modification, it still may not pass with those oversized engines and their negative effect on flight characteristics.
The reported lack of trust, worldwide for the FAA may double or more than double the approvals costs for all American aircraft manufactures for both new models and for modifications.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

Has the FAA been losing credibility for a long time? Or just in response to their delayed response to ground the Max 8?

RE: Another 737 max has crashed during departure in Ethiopia

The NY times is reporting sensors and warning lights that would detect faulty AoA vanes are sold as extras. Neither of the crashed airplanes had them installed:

Link

RE: Another 737 max has crashed during departure in Ethiopia

Quote (RVAmeche)

Has the FAA been losing credibility for a long time? Or just in response to their delayed response to ground the Max 8?
The whole approvals process and the delegation to Boeing of critical safety analysis.
The FAA apparently allowed Boeing to self approve an apparently flawed system.
I am wondering also if and when we will hear allegations of improper political influence on the FAA, and the FAA yielding to outside influence.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

I have a few dumb questions. With the plane in the air at 200+mph, is the angle of attack really that different from the angle of the airplane relative to a level line? Couldn't the AoA sensors be roughly checked against the direction of gravity? Or would it be too rough to be useful?

RE: Another 737 max has crashed during departure in Ethiopia

Quote (HotRod10)

I have a few dumb questions. With the plane in the air at 200+mph, is the angle of attack really that different from the angle of the airplane relative to a level line? Couldn't the AoA sensors be roughly checked against the direction of gravity? Or would it be too rough to be useful?

I was thinking along the same lines. There must be some other condition that could be used to check or limit the MCAS if the AoA don't agree. I know we had the discussion about the usefulness of GPS earlier but suppose you could check the vertical velocity component of the plane. I mean why should MCAS continue to push the nose down if the aircraft is already traveling downward at over 10,000 fpm (ie crashing).

RE: Another 737 max has crashed during departure in Ethiopia

Quote (waross)

The whole approvals process and the delegation to Boeing of critical safety analysis.
The FAA apparently allowed Boeing to self approve an apparently flawed system.
I am wondering also if and when we will hear allegations of improper political influence on the FAA, and the FAA yielding to outside influence.

For sure, I was just wondering if there were other recent instances/incidents that have been building up against them.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
For an extremely limited set of parameters you could construct a table of predicted AoA for airspeeds and weights. Basically a 2 D model.


As soon as you go 3d turning it falls over. As soon as you add in power changes it falls over.

And the biggest witch of all is.... Mother nature up drafts down drafts windshear.

Still air, flying straight and level you could do it.

You want to hit certain angles of attack for efficiency. The airspeeds these occur at vary with weight.

And when you get up high you start getting limited by transonic flow over bits of the airframe which is related to air temperature.
As you get higher the air density drops so for a given AoA the speed is higher.

Eventually you hit what's called coffin corner where if you go faster you get sonic shock waves forming taking out the rear control surfaces and if you go slower you go higher than the critical angle of attack.

And the pilots do check ruffly by setting an attitude. We teach it as pitch plus power equals performance. So for each phase of flight we know what the picture should be either looking out the window or looking at the attitude indicator. You don't actually need any instruments at all in a light single engine piston aircraft to fly it once you know what your doing. You set power by ear and you know what speed your doing by the picture.

Actually your structural..... its none linear geometry winky smile

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
The direction the aircraft is pointing bears no relationship at all to what angle of attack of the wings to the airflow.


IN aerobatics we are quiet often pointing 60 degs up but the aircraft is not stalled. During a spin we are pointing straight down to the ground and everything is stall apart from the rudder.

Just look at a video of a loop or a barrel roll. At no point in those exercises is the plane stalled.

This is the famous one.

https://youtu.be/Ra_khhzuFlE

RE: Another 737 max has crashed during departure in Ethiopia

A MAX8 costs $127M why wouldn't they have three AoA sensors voting? How is the price of an AoA sensor even relevant?

Keith Cress
kcress - http://www.flaminsystems.com

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Because if they added a 3rd sensor in it would come away from the 1960,s type approval. PLus it would have meant that the pilots would have had to do a bit more than a 2 hour CBT which was a huge selling point of the MAX for NG operators.

I don't know of any aircraft with 3 vanes to be honest. They are about 500$ each on my type. They will be cheaper on the max because they will be the same as on the NG so economies of scale.

RE: Another 737 max has crashed during departure in Ethiopia

I guess I don't really understand the "type ratings". I don't see how an additional sensor would alter a 'plane type' or 'controls system type'. I could see how a joy stick would change things from a yoke, but a redundant sensor?

Keith Cress
kcress - http://www.flaminsystems.com

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
The whole Avionics would have to get reworked and it would be a first. Normally they buy in the avionics system from somewhere else eg Honeywell. Which has its own approval they just need to get it approved for the type. With that the avionics would have to go through a full approval as well.

The whole type thing is a bit of mystery to me as well and what requires a new rating, what just requires differences training and what just needs a 2 hour CBT.

For my type the Q400 was meant to have hot wings and most of the engine control stuff done through buttons in the cockpit and it could have also had auto throttle.

But it was decided that if they changed that then it would be a new full type rating which is 3 weeks ground school and 10 4 hours sessions in the sim followed by 4 hours skills test and either another 4 hours in the sim or 4 circuits in the live aircraft.

So they ditched them and it was 2 sessions in the sim and a company differences exam for anyone with a DH8-100,200 or 300 rating. the 100 is nothing like the 400.

The whole point of this stretching and using old type approvals is to do as little additional approvals and certification as possible. So they try and use as much from the previous as possible and only then test and certify the changes. If a new requirement comes along as long as they don't change the system that had prior approval then they don't have to include it. eg control disconnects on the 737, for the last 30 odd years your meant to be able to split both roll and pitch in case of control jams and have duplicate control runs. No requirement in the 60's so the Max doesn't have them now some 57 years later from the first 737 approval. The 787 has them because its a fresh type approval. I don't think the 747-800 has them either.

RE: Another 737 max has crashed during departure in Ethiopia

Quote:

Because if they added a 3rd sensor in it would come away from the 1960's type approval. PLus it would have meant that the pilots would have had to do a bit more than a 2 hour CBT which was a huge selling point of the MAX for NG operators.
I don't know of any aircraft with 3 vanes to be honest. They are about 500$ each on my type. They will be cheaper on the max because they will be the same as on the NG so economies of scale.

By now, this kind of re-certification could be on the table. Boeing is contending with not NEVER delivering hundreds of aircraft. The stakes are high in this game, in the billions.

The cost of the sensor is hardly an issue. Any number of shops could do a hardware installation kit for one of those, for the cost of a few tanks of fuel. Feeding the data in a meaningful way into the MCAS system, then rewriting the software from SCRATCH because it needs a new criticality class would cost millions. That task is beyond the ability of many players in the aerospace industry except those that routinely develop software-driven hardware. I haven't heard yet exactly who developed the MCAS system (I would expect it to be a 3rd party, but it could be Boeing engineers, not making assumptions) then that team working flat out would need more than a year to finish unless they got a LOT of help and had the eye of Sauron on them.

What Alistair is talking about is commonly called "grandfathering" or the continuation of certification rules from a set date in the past. There are good reasons for this practice to continue because 99% of the time changes are minor or don't affect the level of safety in operations. It's that 1% of the time that the change tips over. When doing certification, we regularly do an evaluation of the scope of any change, to determine if it requires a re-evaluation of the certification basis (Transport Canada in my case, but FAA and EASA have equivalents). If the scope is big enough, we could end up using the latest rules, rather than the rules in place when the plane was certified in the past. Even modifiers of aircraft like me do this evaluation, not just the big OEM's. For example, a substantial change would be the adoption of "fly-by-wire" in a previously mechanically controlled aircraft. Other kinds of changes can skirt the edge (but don't usually cross it) like conversion of the interior from passengers to all-cargo, fuselage stretch, or changing from steam-gauges to an all-glass cockpit. If that cargo conversion includes extending the doors, it tips over. If the all-glass cockpit were to reduce the crew workload that you could eliminate one of the pilots, that would definitely tip over an old plane into a re-evaluation under the current rules. That's how the Q400 was grandfathered despite its stretched fuselage.

I've long been convinced that the 737 of today is drastically different from the 737 of 1970. There are some barriers that would be very difficult to cross if the FAA forced Boeing to apply for a new type certificate, using current certification rules to the 737 airframe. Most obvious to a structures guy like me is that after 1970 the required crash loads were changed, but the 737's are all designed to the original levels. In some conditions the floor structure would need to withstand 50% more load to meet today's requirements. There may be a margin of strength already built into the floor structure, so maybe it wouldn't need to be made 50% stronger, but still SHOWING it and fixing the shortcomings are not trivial jobs. This kind of check-and-fix procedure would be required for all points of the design. It would probably not be worth saving, and cheaper to just start with a clean sheet of paper.

For those still reading, here's a mind-bender: The current practice of evaluating the scope of a design change to see if it invalidates the principles in the original design is a rule that came in during the late 1990's. Since the 737 stretches were also done in the mid-1990's they were completed before this new rule came in. If Boeing had tried the NG's after the changed-product rule was introduced, I don't think they would have had such an easy time.

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Another 737 max has crashed during departure in Ethiopia

Follow up:
Has anyone read the Wikipedia page about the Boeing 737?
Has the marketing department of Boeing re-written it recently due to all the attention, or has it always been that way?

Some of the language:

Quote:


The 737 was originally envisioned in 1964...
The primary flight controls are intrinsically safe...
In the event of total hydraulic system failure or double engine failure, they will automatically and seamlessly revert to control via servo tab...

Only a MBA could write this drivel.

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Thanks SparWeb Would you by any chance have anything to do with the Q400? I am due to move to the CS300 some point this year.

RE: Another 737 max has crashed during departure in Ethiopia

For someone not involved in aircraft in any way except as an occasional passenger, and as someone who has always considered Boeing planes to be better than the others, I just wonder if there is an explanation as to why these two, or three, events occurred, while there were many uneventful flights. What was different? Are some airline pilots that much better trained so that they avoided or dealt with this issue? Or something else?

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Human factors is a huge part of most fatalities. It is extremely rare with hindsight that if a human involved had taken another course of action then it couldn't have been avoided. Be that human a loader, technician, ground handler or mostly pilot. Everyone concentrates on the stick monkey. But us stick monkeys know fine that its a huge team effort to get an aircraft from A to B safely. Every human is different and training does play a major role and culture of the nationality and company. Some of us can trouble shoot faster than others but there is a limit to what you can expect the human body and brain to process. We are not super human and not all pilots can have the talents of Neil Armstrong. The aircraft design has to be for the lowest acceptable level of operator.


Now we usually look at the fatalities per million flight hours for an aircraft type.


In its day Concorde was considered the safest aircraft type out there because it had zero fatalities. Then one day one crashed and killed everyone. Because it used to fly relatively few hours compared to other types it went from top of the list to technically the worst in the space of 8 mins.


The MAX has been flying less than 2 years and 376 have been delivered. lion air 189 SOB and Ethiopian 157 SOB. Being extremely generous calling it 18 hours per day for 2 years for each airframe gives 5 million flight hours (this is extremely high its more than likely barely half that).


But that gives fatality rate of 69 fatalities per million flight hours. That is ridiculously and unacceptably high even with my completely inaccurate but very forgiving estimated number of flight hours flown already.

Bombardiers CS300 have produced less aircraft in that period the type flys less hours and has a fatality rate of 0.

The average value for airline transport or part 121 as the FAA calls it is 4.03 fatalities per million flight hours 1998 to 2007.


http://www.planecrashinfo.com/cause.htm

As for if Boeing is better... its historical and company mergers and changes in managment mean that in some ways they are living off the reputation of a completely different company in history. These days there are no bad aircraft that are allowed to fly. They all have there plus points and thier bad. Economics is a major factor in the type a company wants to use. Its the same with the engines as well which are counted seperately to the Hull. In some ways Rolls Royce is living off historical reputation these days as well.

I have never flown an Airbus or a Boeing but wouldn't have a problem if i was told it would be my next type. If i was told it was going to be a MAX I think I would go and get another job thanks very much. 757 with RR engines I think I would have a little sex wee and be prancing around like a 5 year old for days. A380 i would be looking for another job as well but for other reasons.

RE: Another 737 max has crashed during departure in Ethiopia

Alastair and spar Web. Your contributions are what makes this site worth reading above many others and thankyou for your insights.

Hokie, It seems to be a result of faults in sensors. Their failure rate is known and the more hours that are flown the more likely one will fail. Apparently in the previous lion air flight it took a jump seat pilot who was able to detach probably a bit from the overload on the pilots to see what was going on and recommend a course of action that averted disaster. He wasn't there on the next flight.

Now why that sensor wasn't just replaced and not just "tested" is all down to time cost and possibly low amounts of data going from pilot to maintenence technician as to the fault.

I think the key issue here is that previously a faulty AoA sensor might have kicked off anti stall warnings but not taken control of the aircraft without warning or apparently knowledge of the pilots.

Why was that MCAS required? To keep the flying characteristics of the airplane close to its predecessors after doing some fairly major engine mods which have significantly impacted those characteristics.

It's getting pretty clear that there is no quick fix for this issue but I just can't see Boeing going back to the drawing board. It could break the company.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
In the old days they used to have flight engineers to sort things like this out. All the stick monkeys had to do was keep the thing flying.

The FE ran all the checklists and had a far great depth of knowledge about the systems than pilots do.


But as the designs got better, the quality of the parts got more predictable they got rid of the position. Some may say bring them back but before that we used to have navigators and radio operators. Do we really need them... No.

The accident stats have been decreasing since they have all been removed.

But now the focus is on the Design of the aircraft. If its not fit to be operated by two normal human beings it shouldn't be in the sky.

And I to like this site because it doesn't have the nationalistic willy waving that normally occurs in aviation. Plus although I am a stick monkey I still think like an engineer and its nice to talk about these things with people that think the same way.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
That's the cancellations for orders started.


I suspect they may end up scrapping the model.

RE: Another 737 max has crashed during departure in Ethiopia

From my rough understanding (Feel free to correct me, my exposure to FAA is from 10,000km) the rot at the FAA started in the 80's with giving increasing power to the manufactures, and accelerated over the last 10 or more years with chronic under-funding, unstable funding and regulation lag. There also appears to be issues with their ability to take action on unsafe aircraft, at least one AD's on Robinson helicopters blade delamination only came about after a pacific island nation spent a large amount of cash fishing all the blade bits out of a lagoon, the accident investigator was left with the impression that the FAA knew all about the critical issue but couldn't take action without evidence from an outside source, mention was also made about underfunding of NTSB resulting insufficient number of accident investigations being undertaken.

Quote (Alistair_Heaton)

Human factors is a huge part of most fatalities. It is extremely rare with hindsight that if a human involved had taken another course of action then it couldn't have been avoided. Be that human a loader, technician, ground handler or mostly pilot.
Depressingly much of what tends to be credited to pilot errors is actually bad design, the Airbus side sticks is a classic come to mind.

For those that actually would like to see the certification quagmire that the 737 max has become the applicable section starts at page 68, the certification table starts page 71, on other aircraft it can consist of little more that all regulations applicable at amendment XX.
https://rgl.faa.gov/Regulatory_and_Guidance_Librar...

The certification grandfathering drives some odd features, on a cargo converted 737 classic the cargo barrier is at a higher certification amendment than the aft side of the cockpit wall, so after a few attempts the conversion design orginisation put aft facing seats for the supernumerarys on the cockpit wall because ones forward facing ones on the cargo barrier would have been to a higher spec and hence more expense.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
"Depressingly much of what tends to be credited to pilot errors is actually bad design"

And a bad design in the first iteration is known about but progresses through 50 years with soft fixes through training instead of changing it through grandfather rights because it is cheaper than fixing it because the end user pays for training.

RE: Another 737 max has crashed during departure in Ethiopia

Quote (Alistair Heation)

That's the cancellations for orders started.
That's interesting. I work at a sub tier supplier and our parts end up at Boeing (among others) on the 737s. We happened to have our quarterly all hands meetings yesterday and there was a long discussion about the 737 Max issues. We were told that our customers have contacted us and assured that there would be no drop in purchasing and to continue manufacturing at full steam.

Could be because we're a long lead time product... or just because they want to make everything sound rainbows and sunshine. It's worrying to see cancellations for aircraft though.

RE: Another 737 max has crashed during departure in Ethiopia

I thank you too Alistair and Spar as you've provided me with a lot more understanding of "ratings".


Changing subject a bit. If the MAX has 2 AoA sensors why didn't the calm one win? Software should've detected one changing radically and flagged it while ignoring it. Or is there only one?

Keith Cress
kcress - http://www.flaminsystems.com

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Garuda is wanting to cancel 49 airframes.

5 Billion $ order.

Vietjet is also talking about it 25 billion 200 airframes

And Kenya Airways 30 aircraft at 3.56 billion.

If your parts are generic for NG and MAX product lines I can't see a drop in demand. People are not going to stop flying the NG's because of an issue with the MAX. If your product is only used in the MAX which i doubt because you state among others then things might change quiet quickly. I really can;t see it getting released for service any time soon.


"Changing subject a bit. If the MAX has 2 AoA sensors why didn't the calm one win? Software should've detected one changing radically and flagged it while ignoring it. Or is there only one? "

There is two but apparently the MCAS only uses the input for one of them per flight and flips between them.

Normally in my experience with avionics miss matches its left to the pilot to decide which one is given the correct reading. What the machine does is flag up that there is a comparison error between them. Problem with AoA is that is quiet common that they do disagree depending on the manoveur being under taken.

Airsped a difference of 5 knts, Altitude is 60 ft, heading is 6 degrees all trigger comparison errors. When it happens we look at the standby system and say that one is shite twiddle a knob and the display turns yellow to indicate we are in a reduced tolerance mode and manually have to check the standby system and we continue the flight. BUt again we are back to this 3 system redundancy. I can take one AoA vane out of the system but it requires a circuit break pull. We know its happened because we get a caution about icing gear and the low and high speed protection goes nuts. So we get a spurious stick shaker or over speed warning. After we pull it, it then takes the stall protection system out of action and I can't fly in icing conditions any more. And the plane is gorunded as soon as I land.

To note i don't know of any commercial aircraft being flown today apart from test bed aircraft and those ones that fly into hurrancanes that are fitted with more than 2 AoA sensors.

RE: Another 737 max has crashed during departure in Ethiopia

It smoked - It appears as if the MCAS only takes readings from one sensor (I think the one on the captains side). As I understand it the two halves of the cockpit - Captain and FO have a set of readings from units on their own side of the aircraft. with only two sensors, if there is a difference between them then there are alarms - the issue here is that the alarm for AoA disagree was an extra which the planes didn't have fitted (!!) Apparently these are now going to be part of the basic pack, but the actual AoA readings are still going to be an extra. Someone in Boeing is making a bad call there.

IIRC the Lion air crash reported that the captains unit was the one failing and he had the "stick shaker" active for most of the flight whereas the FO didn't.

The issue with one failing and one not is that the computer doesn't know which one to look at and hence you get all these disagree alarms going off. There is also some evidence that the airspeed signals may have been affected also from the reports from the pilot of Ethiopian airlines, but that isn't clear.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
It flips between which sensor apparently so the first flight of the day is the No 1 sensor which is the captains side then the next flight the Number 2 on the fo's side. Repeat until there is a full shut down power cycle. Which I suspect was half the problem trying to work out what was going on with the lion air aircraft. One sector the crew was saying everything was fine the next they were saying they were getting trim runaway. Get back to the ground turn the aircraft off, tech come to fix it and turn everything on to test it and everything works fine. Next flight departs and everything good pilots think great they have fixed it..... Second flight the shit hits the fan again because it was the other one that was faulty.

There needs to be a way of killing the MCAS without loosing the electrical trim system as well. That will take the Autopilot away as well.

RE: Another 737 max has crashed during departure in Ethiopia

Thanks - kind of makes sense that it would alternate inputs.

I thought that an MCAS disable button would be the way to go, but that clearly has issues in that it is a critical part of the flight control system and would disable what was designed as an important safety element in preventing an accidental stall condition. Hence solve one problem and potentially create another one.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
To be perfectly honest...

Overspeed is usually the problem with pilots.... not stalling....

I would have thought that a logic system turning it off for take off until 10 000 feet would be feasible.

RE: Another 737 max has crashed during departure in Ethiopia

With the AoA sensors being such a cheap but critical part of a system that has the potential to cause the plane to dive into the ground, I would think that mounting maybe 3 of them on each side would be a prudent move. That way, if one fails, there should still be 2 in agreement that it can use. It there aren't at least 2 matching, then the system warns the pilots and bypasses the stall avoidance subroutine.

RE: Another 737 max has crashed during departure in Ethiopia

It's not quite that simple.

The AOA sensor is an aerodynamic device. Similar to a pitot tube, It needs 'clean' air, to function; it also (unlike a pitot tube) needs to be positioned in a specific way relative to the aircraft pitch axis to function correctly.

In other words, you can't just add more next to the existing ones.

Even if you could, the software and processing hardware that interacts with these devices is, by definition, extremely complicated. The amount of traffic between systems and the level of internal code error checking is extreme. This is why third parties provide the systems- design is complicated and expensive.

Adding $2,000 of additional AoA sensors might mean literally tens of millions of dollars in additional engineering time to make them function safely. That's no comfort to the families of those lost on these flights, but it's an economic calculus that is being made either way.

RE: Another 737 max has crashed during departure in Ethiopia

Not that the AoA sensors are the only thing that could go wrong with the MCAS, but is there a way to manually switch the sensor that's being used or does it only switch automatically at each take-off?

RE: Another 737 max has crashed during departure in Ethiopia

A lot of people will not fly on a 737 Max8.
Additionally a lot of not sophisticated but worried people will not want to fly on any 737 or Boeing.
The reasoning being;
"I really don't know the difference so to be safe I won't fly on any Boeing."

Does anyone remember Konica? Not Konica Minolta.
Konica had a fully automatic, dependable and easy to use automatic exposure system in the 60s.
Konica's Hexanon lenses were among the finest lenses in the world. Hexanon lenses were selected by the Japanese government as the standard against which all other lenses were compared.
Then they released the TC-X 1985 – 1987
Built by Cosina for Konica, fully mechanical SLR
First SLR in the world with body and frame completely cast of plastic
First camera in the world that uses DX coding on film cartridge for film speed setting
It was reported that the plastic turned out to be not dimensionally stable.
This may have been public perception rather than the actual reality, but was told to me by a dealer when I questioned why Konica cameras and lenses were no longer stocked.
Konica lost the trust of their dealers and lost their dealer network.
While cameras were not Konica's only business, the model TC-X marked the end of their single lens reflex camera business.
20 years of fine cameras and one bad model ended their camera business.

If the Max8 leads to a re-evaluation of the FAA's grandfathering provisions this could mark the beginning of the end of the 737.


Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

Quote (waross (Electrical))

If the Max8 leads to a re-evaluation of the FAA's grandfathering provisions this could mark the beginning of the end of the 737.

Since FAA does not have the resources it can sublet the new evaluation back to Boeing. Have we not seen it before?

RE: Another 737 max has crashed during departure in Ethiopia

Alistair;
With respect. I am not challenging you. I am wondering whether my reasoning is valid.
I read with interest your link to planecrashinfo.
I note that mechanical failures account for only 17% of fatal aircraft accidents.
That would make the statistics on the MAX 8 about 6 times worse than your initial estimate.
But the general heading of Mechanical includes;
Engine failure,
Equipment failure,
Structural failure,
Design flaw,
and
Maintenance error.
So design flaw is only a part of the 17%.
In the table:
Notable Accident Causes by Category,
Design flaws account for only 17 out of 212 accidents.
That's down to 8% of total accidents.

Quote (Alistair)

The average value for airline transport or part 121 as the FAA calls it is 4.03 fatalities per million flight hours 1998 to 2007.
May we apply the 8% to this figure and call the average number of accidents due to design flaws 4.03 x 8% = 0.322 fatalities per million flight hours?
Now we are over 12 times worse than your initial estimate.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

waross, from a philosophical perspective, I would say design factors play a role in EVERY crash. Think of a simple hand launched balsawood toy glider, built with adequate structural safety margin, ample dihedral, positive longitudinal stability, and balanced aerodynamic surface areas. Almost nothing could make it crash. By contrast, the MCAS, for example, based on one faulty input, if left to its own devices is guaranteed to crash the aircraft, and appears to have done so on two occasions against determined human opposition.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
Crashes are very rarely down to one factor.

Usually it's something then the human gets involved and due to their actions it becomes worse than it needs to be.

In fact I just had the qrh out this evening with a problem in flight with pressurisation. We spotted it while climbing so leveled off at FL 100 and had enough fuel to get to destination so continued. Got a new fuel plan for going back at fl100 and the technicians replace the rear outflow valve when we got back. A complete none event. If we hadn't spotted it on the way up before the warnings went on then we would have had to descend quickly with the cabin crew doing service hot drinks going every where and trolley s rolling about with the nose pitched down by 20 Deg.

You can't fiddle with the fatalities per million flight hours. It's a straight number unrelated to the other accident figures. Most accidents these days are aircraft going off the runway and nobody killed.

RE: Another 737 max has crashed during departure in Ethiopia

Quote (Alistair_Heaton)

Crashes are very rarely down to one factor
From what I’ve read about air and rail crashes and what I’ve personally determined about electrical system events I’d change “very rarely” to “never”. Even two factors is astronomically improbable.

RE: Another 737 max has crashed during departure in Ethiopia

Thank you Alistair.

I agree David. Three contributing factors is more common.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

Hemi;
I was comparing numbers under headings in a table. All crashes versus crashes due to design flaws.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

Quote:

Thanks SparWeb Would you by any chance have anything to do with the Q400? I am due to move to the CS300 some point this year.

Not directly, but plenty of 100's to 300's cycling through the facility where I work. My resumé has a lot of spicy stuff on it.
Oh I envy you - I'm sure you're very eager to switch to the C-Series jets!
What about the other Bombardier stable-mates, like the RJ's and Globals?
Or are you having so much fun (not) doing emergency descents in the Q400 that you never get the chance? wink

A quick summary on my thoughts about a few of the recent comments:

I doubt that the grandfathering clauses would be changed by this accident. Restricting that would make many aircraft operations completely uneconomical. By an order of magnitude. Not exaggerating! It would prohibit any aircraft more than 10 years old from flying.

The causes of this accident appear (for now) to be from a bad system safety assessment, and that (for what it's worth) is a very modern process of analysis. It didn't exist in the 70's but definitely a hallmark of modern avionics design now. The failure, we believe, is in the assumptions and conditions used for the analysis. If the audience is willing, I can show you some of these assumptions and how they affect certification of equipment. Takes a bit of time to prepare that kind of stuff, but I'm game if you are.

I take the comments by Chesley Sullenberger seriously. If he's concerned about the FAA, then so am I. My work has some projects that have been stalled by the US government shut-down and a few still are delayed, and I'm not even working at a US company! It must be awful for the aviation companies that are in the USA.

Canada (and EASA) may be taking upon themselves a detailed review of the 737 certification. I hear rumours and rumblings from Transport Canada that a resources are being moved to respond to this need. Last fall I attended a seminar on system safety analysis (only 1 week after the Lion Air crash; how I regret not asking a question at the time). The expert at Transport Canada had a tremendous grasp on the issues and methods to assure reliability of modern aircraft systems. He was even reporting some cutting edge stuff like avionics faults that could be traced to cosmic radiation (facts to back it up!). I have a lot of faith that if people at TC, like this person, are evaluating the Boeing certification, independently of the FAA, that we WILL get to the bottom of these tragedies.

It just can't happen quickly enough.

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

RE: Another 737 max has crashed during departure in Ethiopia

Hi SparWeb. I didn't mean to imply that there would be no more grandfathering, just that it may become more restrictive.
If TC and EASA move towards more restrictive grandfathering there will be a lot of pressure on the US industry and the FAA to follow.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

Quote (waross)

20 years of fine cameras and one bad model ended their camera business.
Yet somehow, GM survive the Vega.

Brad Waybright

It's all okay as long as it's okay.

RE: Another 737 max has crashed during departure in Ethiopia

waross, I wasn't taking issue with your post. But I think you missed my point. Any aircraft design can be crashed. Some will do it on their own, while others put up more of a fight. Ergo, the design plays a role in all crashes. In other words, a really good design needs a lot of serious contributing factors before it will crash.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Another 737 max has crashed during departure in Ethiopia

One can foresee Boeing’s future could hinge on how the technical argument develops. After the two fatal incidents the MCAS system in the 737 Max8 is now implicated as it can “create” or “generate” an accident. MCAS can automatically initiate an Aircraft Nose Down (AND) after the flap has been retracted and the Angle of Attack (AoA) sensor gives out an erroneous reading. If the pilot counteracts the AND with an Aircraft Nose Up (ANU) by manually trimming the stability the aircraft’s tail the MCAS could repeat itself to fight the pilot’s intervention. This in-fighting between human and an automatic system was recorded in detail in the Indonesian plane's blackbox for over two dozen times. The end result was MCAS could in each automatic trim swivel the horizontally tail further to increase its aerodynamic resistance until it become too difficult for the pilot to trim it back. MCAS won in both occasions and downed the planes.

Boeing could be criticized for not coming clean with what the MCAS could do to the plane and only issued the relevant information after the first accident . The doomed Indonesian plane in the previous fight had a similar tug of war between the pilot and the MCAS system but was stopped by a jump-seat pilot’s advice to switch off the MCAS by the cut off switch of the Stability Trim. The maintenance competency and the safety culture of the Indonesian carrier were criticized but the downed 737 Max8 plane was only 2.5 months old and has not had its minor and major check maintenance yet.

Unless other shortcomings come to light Boeing can claim 737 Max8 is safe as long as the pilot flips the cut out switch terminating the unwanted intervention of MCAS triggered by a defective AoA sensor. This argument will probably difficult to rebuff if Boeing does not patch the MCAS system. If Boeing finds it necessary to change the MCAS materially then it would be an admission of gilt for a bad if not unsafe design, would it not?

In any case would it be fair to a pilot to be ready in full combat mode to fight the MCAS system a few minutes after the plane leaves the ground when the flap is retracting to its home position, say in six minutes like the Ethiopian accident? No doubt the two Ethiopian pilots would be criticize not remembering by heart to flip the cut off switch mentioned in the FAA directives released after the Indonesian accident but would the flight carriers still buy the 737 Max8 after knowing its nasty MCAS system that claims to be a safe feature but in fact dangerous if not switched off in an event of a frequently occurred sensor error. No doubt if the senor is defective it got nothing to do with Boeing’s design or installation and most probably just a supply chain issue.

RE: Another 737 max has crashed during departure in Ethiopia

Nicely summed up saikee.

Repetitively played tug-of-war between the pilots and the MCAS with the MCAS cheating by having more authority available than the pilots.

Like a game of Monopoly with the banker having sticky fingers.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
If the solution is do nothing to the MCAS....

I know what the pilots solution will be....

Turn the electrical trim off for takeoff. And only turn back on with 10k worth of fresh air under your arse.

RE: Another 737 max has crashed during departure in Ethiopia

Yeah.

Sadly, I suspect this MCAS issue would never ever take another plane down. The problem is essentially solved now. (Though sketchy AoA sensors need to be eliminated.)

I'm sure right now the thinking of every last MAX pilot - everyone of them - is 'any hint of vertical irregularities' TURN OFF MCAS.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Another 737 max has crashed during departure in Ethiopia

I recently came across the story of QF72 (2008).

"The....Australian Transport Safety Bureau....finds incorrect data on measures such as airspeed and angle of attack (a critical parameter used to control an aircraft's pitch) was sent by one of the A330's three air-data computers – each of which has its own sensors on the fuselage – to other systems on the plane. One of the three flight control primary computers then reacted to the angle-of-attack data by commanding the plane to nosedive."

It's curious that the lessons are just not being learned. Some subtly-flawed logic remains in place as accepted design dogma, leading to unnecessary incidents.

Note also that this mentions triple redundancy. So the ultimate solution isn't that.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
When I get home tonight I will find the accident report for that one. Then we can see what the engineering is and miss out the jorno crap.

Never done a type rating on a proper bus but I know they have 2-3 different flight laws. There are also a load of protection systems such as alpha floor.

The a330 does have 3 air data computers but only 2 AoA vanes according to my geeky plane spotting first officer.

RE: Another 737 max has crashed during departure in Ethiopia

I just perused the report (it's long and I didn't read the whole thing yet). Section 2.6.1 'Role of software in safety-critical systems' gives a good summary of the accident and the associated risks that maybe contributed to the 737 MAX crashes too.

Brad Waybright

It's all okay as long as it's okay.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
You got a link to so I don't have to go looking for it?

RE: Another 737 max has crashed during departure in Ethiopia

How about stepping back and looking at the overall picture.
I understand that the MCAS system was implemented to compensate for flight characteristics caused by the new engines.
Maybe the solution is to use higher landing gear and put the engines in a position that does not need MCAS.
MCAS may not be the only problem with the MAX8.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

Quote (AH)

The A330 does have 3 air data computers but only 2 AoA vanes according to my geeky plane spotting first officer.

QF72 report (footnote 28, page 15): "There were three AOA sensors, three pitot probes and six static ports on the aircraft. There were only two TAT probes; one provided data direct to ADIRUs 1 and 3, the other provided data direct to ADIRU 2."

Quote (AH)

...the jorno crap...

That's a bit harsh. smile The linked article appears to quite reasonable.

Keep in mind that even an official investigation can sometimes be short-sighted (at first), requiring an interested party to push - in this example combined with luck in actually finding further physical evidence. e.g. UA 811

RE: Another 737 max has crashed during departure in Ethiopia

Quote (waross)

MCAS may not be the only problem with the MAX8

May be but it is bad enough for some if

(1) The existence of MCAS was not communicated to the purchasers who bought the plane nor the pilots who flew the aircraft.
(2) MCAS was not part of the pilot’s operating manual for the plane.
(3) No MCAS training was ever planned for the pilots until the system started to kill everybody in the 737 Max plane.
(4) MCAS can take over the plane based on just one faulty senor’s erroneous signals to make the plane dose-dive. It can repeat itself if the pilot intervenes. It does not stop until the plane is destroyed. This is known to cause the first fatal accident. The second accident has remarkable similarities. The jackscrew found in the second crash site has been reported in the full nose-dive position. Ethiopian authority has indicated “to the best of their knowledge” the MCAS was in play for the brief duration of flight 302 from Addis Ababa
(5) The sudden take over by MCAS has been reported by American pilots too and aired in specially arranged channels.
(6) The logged/established MCAS malfunctions are (1) Indonesian plane flight immediately prior to the accident (stopped by a kill switch by a off duty pilot), (2) Indonesian doomed flight in Oct 2018 and (3) Ethiopian doomed flight in Mar 2019. Even the anonymous reports by the American pilots are totally ignored the fault frequency of MCAS is one should never be associated with commercial passenger flights.
(7) Unless the pilots remember and know how to activate the kill switch the MCAS system is so lethal that it could kick in so quickly during the take off to leave insufficient time for the pilot to return back to the airport. The first Indonesian and the second Ethiopian planes were crashed in 12 and 6 minutes respectively.

If the public were force the manufactuer's CEO to fly the 737 Max to show the safety of his plane I will bet my money that he would put his hand on the kill switch (Stab Trim cut off) before giving the pilot the green light to take off.

I am sure the intention of MCAS is good and the installation is essential to the operation of 737 Max but its implementation is now a laughing stock for the manufacturer. It would be revealing to see how much engineering has been compromised by the commercial interest in the coming investigations.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)

For all you prejudiced idiots who think 'simple' pilot incompetence killed 346 innocent people in the Lion Air and Ethiopian crashes, here is another captain who agrees with me:

Boeing (and many posters) say "Hey, it's just a trim runaway. Do the drill and all is good." But this is not the simple trim runaway that the QRH contemplates. It starts with a stall warning stick shaker shortly after lift off. Close to the ground this will, and should consume both pilots' undivided attention. After a number of seconds they realise that the airplane hasn't stalled and they start figuring out that they may have an airspeed and/or AOA problem.

This is a second problem to deal with on top of the first. And they can't shut the &%$#@ stick shaker off once they realise that it may be spurious. The PM will be frantically scanning the panel to try and find some clue what is going on. And this whole time, among the din of the stick shaker, the crew's concern for the airplane's flight path, and the confusing instrument indications, MCAS has been intermittently dialing in nose down trim. Not steadily, in a calm cockpit at altitude like the QRH contemplates.

But intermittently in the background of chaos, noise, and confusion. At some point, well past when it would have been timely, the task saturated PF realizes that the trim is working against him/her and the stab cutout switches get turned off. (hopefully). But the shitshow isn't over. Because of everything else going on, this took too long and the airplane is way out of trim. The Lion Air crew reportedly had 60 KG of back pressure on the yoke. Close to the ground, and relying on the lifting component of the underslung engines to help keep the nose up, the crew do not dare reduce power. Now the crew needs to manually trim the airplane, but the airplane is way, way off its trim speed. The B737 QRH makes reference to the large forces that may be required to break free a servo clutch:

"3 If needed: Use force to cause the disconnect clutch to disengage. Approximately 1/2 turn of the stabilizer trim wheel may be needed. Note: A maximum two-pilot effort on the trim wheels will not cause a cable or system failure."
Worse, the "Manual Stabilizer Trim" section of the Boeing FCTM talks about the air loads on a grossly out of trim stab requiring a speed change to reduce the force required to manually trim:
"Excessive air loads on the stabilizer may require effort by both pilots to correct mis-trim. In extreme cases it may be necessary to aerodynamically relieve the air loads to allow manual trimming. Accelerate or decelerate towards the in-trim speed while attempting to trim manually."
Sweet Jesus how did this thing get certified?

A guy (or petite gal) has a 60 KG+ force on the yoke trying to stop the airplane from impaling itself into the hard ground just a few thousand feet below, and now he/she has to brute force trim the airplane as well, requiring involved coordination with the PM. Still with all the stick shakers, aural warnings, goofy instrument readings, and whatever else is happening to distract the crew and making communication almost impossible. It is not hard to see how quickly it becomes overwhelming. In addition to a fix for the airplane, if they keep the MCAS system (instead of designing a whole new wing or tail for the airplane), they will have to train the pilots who fly it to deal with its failure.

Right now, there is not a single Max pilot in the world who has been trained for this failure because - there isn't a single simulator in the world that can replicate it. But when they do, all those pilots that claimed "it's just a trim runaway" are going to have a very eye opening simulator session."

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
the above is from a 10k hour skipper on NG 737 and he is a yank

RE: Another 737 max has crashed during departure in Ethiopia

Is there also a piece that says it's reasonable to anticipate a trim runaway if you've been fiddling with the trim, but otherwise, not? Or is that not true any more (or has it never really been true?)

A.

RE: Another 737 max has crashed during departure in Ethiopia

The more I read about 737 Max and MCAS the more I am convinced of FAA culpable of the two disasters.

Alistair Heaton's suggestion, of the manufacturer's training of the pilots should be directed to coping with the failure of the MCAS, sounds like hitting the nail on its head. Who give the rat ass about the MCAS. The public needs the pilots trained to survive the events when the damn thing fails to work.

RE: Another 737 max has crashed during departure in Ethiopia

Have I got this right?
The placement and the power of the new engines could cause unacceptable flight characteristics under some flight conditions.
It is during high power operation during climbs such as is common during take-offs that the unwanted flight characteristics are liable to occur.
MCAS was implemented to counteract this unwanted effect of the new engines.
Most pilots will be turning the MCAS system off during take-offs in the interests of safety and self preservation.
So, during the time when MCAS is most needed, it will in the future be turned off?
Maybe it's time to rethink the engine application.

We hear a lot about the expense of pilot retraining.
With a claimed 8% saving in fuel consumption, how many flights would it take to save the cost of retraining?

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

If the plane is acceptably flyable without MCAS then why does MCAS exist?
If the plane is not acceptably flyable without MCAS then what bad things will happen with it turned off?

RE: Another 737 max has crashed during departure in Ethiopia

A challenge to Boeing and the FAA:
When the first simulator is programed to simulate a failed MCAS on a 737 MAX8, send a few dozen pilots who have had the present MAX8 upgrade training and see how many of them can handle a failed MCAS during take-off.
I suggest that one failure is one too many.
I suspect that there will be more than one failure.
Then, Boeing and the FAA execs, do not pass Go......

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
you can't turn it off. the only way you can kill it is by turning off the electric trim system.

The aircraft would not pass certification without MCAS

And there is one sim in the world with MCAS simulated. that's Boeings one.

RE: Another 737 max has crashed during departure in Ethiopia

There are a few posts here that keep talking about turning the MCAS off.

You can't turn it off and don't even know whether it is the issue or not. There's no alarm or light or anything that I've heard to say MCAS active.

The only thing the poor pilot can do is turn off the electric power to the motor on the elevator trim. However if the system has already commanded a nose down and then you turn the power off you need to manually wind the trim back which could take several thousand feet of air you don't have.

Also MCAS is a required safety feature which is designed to stop a stall occurring dye to the lift being generated by these new engine nacalles. Turn off the elevator trim motors on take off and you can't trim the aircraft for climb and you risk a stall.

I don't know if the MCAS takes in other data like air speed or just the AoA sensor so even the (optional) AoA disagree light might not alert a pilot to the operation of this "hidden" piece of software if it uses other data. The ET pilot apparently reported air speed indicator issues but we will need to see the FDR info to be sure.

So basically Boeing are in a complete pickle on this. Their relative silence is deafening.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Another 737 max has crashed during departure in Ethiopia

(OP)
you can manually trim which is not that onerous because you set the trim before departure.

the recovering trim from full forward manually is the issue. Once its back to something sensible you can fly it no problems manually.

Nobody outside boeing seems to have a clue what data sources it uses.

RE: Another 737 max has crashed during departure in Ethiopia

Reported on AVweb;

'According to reports, Boeing is set to confirm changes previously reported as considered, which include: changing the MCAS configuration to accept data from both angle-of-attack sensors rather than just one; limit the number of times MCAS can drive the stabilizer to affect nose-down pitch; and limit the duration of the events to 10 seconds. Preliminary reports from both the Lion Air and Ethiopian Airlines accidents suggest that MCAS continually tried to offset the pilots’ efforts to level the aircraft. In addition, new coding will make MCAS disengage if it sees a differential in AOA sensor readings of more than 5 degrees.'

Brad Waybright

It's all okay as long as it's okay.

RE: Another 737 max has crashed during departure in Ethiopia

I read an interesting article today that the only place MCAS is mentioned by name in the 737MAX manuals is in the Glossary. Other than that, the system is not referred to at all.

Was it deliberately left out so that training could be simplified? That seems to be the implication.

RE: Another 737 max has crashed during departure in Ethiopia

Although turning off MCAS and manually trimming is obviously the best course in a malfunction, even if it's ideally trimmed it's going to leave the plane with the original tendency to stall at high AoA as depicted in the graph AH posted March 19. I wonder how easy it is to stall this plane without MCAS.

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