Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by BTD » Fri Apr 05, 2019 8:50 pm

We have all read and seen the accident reports of a competent crew flying a perfectly good airplane into the ground. It has happened so many times in the last 50 years. Human factor considerations are usually involved in some form or another. Things we are all susceptible to.

Now we have an aircraft that develops a fault that takes you 90% of the way to the crash then demands that you do a procedure perfectly in a very short period of time all while throwing as many distractions at you that the airplane can think of. And even then you may have to do a little fancy foot work to get out of it by reading between the lines of the provided QRH procedure. Good luck. And it does this almost by design.

Remember a few min before, these guys were probably thinking of where they were going to eat dinner that night. Not planning for the fight of their life.

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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by TailwheelPilot » Fri Apr 05, 2019 10:04 pm

MCAS is obviously a problem with the MAX, but every accident has a sequence and typically numerous holes leading to a crash.

The manual trim wheel may not work at extreme stabilizer positions, but as has been mentioned the manual electric trim worked fine and overrode MCAS commands. Cutout in normal position, trim the plane with manual electric trim for current conditions, then cutout within five seconds of the end of manual electric trimming (ie before MCAS reactivates). After that the manual trim wheel should work fine to turn around and land since the stabilizer is starting in a trimmed position, not an extreme position, there are no high air loads fighting you.

To me it looks like in the heat of the moment the cutoffs were flipped while trimming ANU but before the aircraft was trimmed for a climb (or cruise). If they had realized they were bringing the stabilizer back to a more typical position and waited another 5-10 seconds to flip the cutout switches it may have made all the difference.

It also appears that the cutoffs were switched back to normal position at some point (given an AND command had no effect ~05:40:42) but two quick (possibly not intentional) blips on the manual electric trim towards the end of the flight did trim slightly ANU. Sadly those blips also reactivated (I think I read that somewhere) the MCAS that pushed them over the top.

A few other things intrigue me.

Flaps go up, shit hits the fan.

Why would one not immediately return to the last stable configuration? Is this something I think of because of tailplane icing training? After the Lion Air accident highlighted MCAS and that it was only active with flaps up (among other conditions), I would have thought control issues when flaps came up would be a good excuse to put flaps back down one notch, just in case it was MCAS. Arguably a simpler procedure on departure than flipping the cutout switches and losing manual electric trim.

Finally, if the PF stick shaker activates when obviously not correct (ie high power, just airborne normally, day VMC) is there a good reason not to transfer control to the PM? Curious since the one Lion Air flight did so and continued to Jakarta (although I have heard they have/had a policy of low-time co-pilots not touching the controls below 10,000').
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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by '97 Tercel » Fri Apr 05, 2019 10:47 pm

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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by J31 » Fri Apr 05, 2019 11:02 pm

Last week Boeing was very bullish on having a fix in short order. Now this week they seem to be eating humble pie.

Why the change in attitude?

Generally the B737 initial climb procedure is to fly V2 +15-25kts to 1000 agl. Then you start accelerating, retract the flaps, and continue climb at minimum clean speed to 3000 AGL. During manual flight there can be a lot of Speed Trim System (STS) action going on.

Speed Trim System is a speed augmentation system introduced on the B737 Classics starting with the B737-300. The purpose STS is to return the airplane to a trimmed speed. It can be overridden by the control yoke electric trim switches.

There is also substantial reduction in pitch as you accelerate to min clean speed. Once the flaps are up MCAS operation could be initially be mistaken as STS operation.

As we see from the preliminary report, MCAS sensed an erroneous left hand AOA and over about 30 seconds trimmed nose down to 0.4 units. That is almost full nose down trim! At this point I would think that the pilots would have had almost full up elevator to maintain level flight.

Many of us are wondering why the captain did not appear to run the nose up trim longer. Maybe there was more going on that Boeing/FAA/NTSB/Ethiopia has discovered?

There is lots of talk about how the air loads can make moving the trim manually difficult to impossible.

At one point the Captain asked the f/o to trim up with him. It makes my wonder if the air loads rapidly overcame the electric trim motor causing it to stall when the Captain trimmed nose up?
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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by Eric Janson » Sat Apr 06, 2019 2:27 am

One thing that I don't understand - is why the configuration was changed.

Why clean up if the intention is to return to the departure airport?

I thought the Boeing procedure was to maintain configuration - can any 737 Pilots confirm?

If the aircraft is flying fine in its current configuration then I'd just leave well enough alone. I'm a firm believer in keeping things simple.

I normally write the pitch/power combination for level flight in the take-off configuration on the flightplan as a quick reference. Also write down the pitch/power combination for level flight in the clean configuration.
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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by BTD » Sat Apr 06, 2019 6:02 am

Eric Janson wrote:
Sat Apr 06, 2019 2:27 am
One thing that I don't understand - is why the configuration was changed.

Why clean up if the intention is to return to the departure airport?

I thought the Boeing procedure was to maintain configuration - can any 737 Pilots confirm?

If the aircraft is flying fine in its current configuration then I'd just leave well enough alone. I'm a firm believer in keeping things simple.

I normally write the pitch/power combination for level flight in the take-off configuration on the flightplan as a quick reference. Also write down the pitch/power combination for level flight in the clean configuration.
We don’t know yet if there was unreliable airspeed or an IAS disagree from the prelim In the Ethiopian case. If there was no indication to the crew that there was unreliable airspeed I don’t see why you wouldn’t clean up. Knowing what we know now about MCAS of course we wouldn’t.

But there is no QRH procedure or memory item for a false stick shaker. Once determined it is false then I can follow the logic of ignore it, as best you can, clean up, climb to a safe altitude and deal with it then. If they had an IAS disagree then that would change things.

Edit to add. I believe this crew was dealing with a nightmare scenario, however, there are some convenient holes left in the preliminary data that was released. I don’t know why that is, but it makes drawing any concrete conclusions impossible.
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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by Gino Under » Sat Apr 06, 2019 6:06 am

We all know stall recovery is achieved by simply reducing the angle of attack. As I understand it, in both of these losses, the stab was at the fully nose down position. I don’t believe the crew in either case placed the stab in that position. It is curious to me how Boeing, as a software solution, would allow the stab to run to such an extreme when they clearly understood it could end up in that position.
The NG and MAX both have AoA available for display on the PFD if the customer chooses to pin it there. Most don’t. Maybe it’s time pilots started using it. If the AoA signal is determined to have failed or is invalid when ground speed is greater than 80 knots, the AoA indicator will be blanked and replaced with a fail flag.

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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by BTD » Sat Apr 06, 2019 8:35 am

Gino Under wrote:
Sat Apr 06, 2019 6:06 am
I don’t believe the crew in either case placed the stab in that position. It is curious to me how Boeing, as a software solution, would allow the stab to run to such an extreme when they clearly understood it could end up in that position.

Gino
There isn’t much to believe. The FDR makes it clear the stab nose down trim was an automatic input and not initiated by the crew. When the stick shaker went there was a nose down column input and a slight decrease in the vertical g loading, but not much. They seemed to realize it was false very quickly. The QRH for stall recoverery does mention to use nose down trim if required, but it wasn’t done here according to the fdr.
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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by pelmet » Tue Apr 09, 2019 12:35 am

I haven't commented yet because I have nothing to add and haven't flown any newer 737's. Pretty much been only reading what is in Fight International and Aviation Week mags to avoid the huge threads. But I think that this information link may be interesting for some.....

https://www.satcom.guru/2019/04/stabili ... range.html
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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by SheriffPatGarrett » Tue Apr 09, 2019 9:40 pm

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Boeing, as much today as it was when I flew it in the seventies in gravel pits...IT WAS GARBAGE!

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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by valleyboy » Wed Apr 10, 2019 6:02 am

I came across this and it seems to be the be pretty authentic. It is getting "thumbs up" from 73 max pilots. I'm not sure how he got his information but it sure disputes the announcement that the crew reacted and followed the proper procedures. Seems to me there is some spin doctoring going on from the authorities.

[youtube][youtube]https://youtu.be/HBqDcUqJ5_Q[/youtube][/youtube]
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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by valleyboy » Wed Apr 10, 2019 6:02 am

I came across this and it seems to be the be pretty authentic and good delivery. It is getting "thumbs up" from 73 max pilots. I'm not sure how he got his information but it sure disputes the announcement that the crew reacted and followed the proper procedures. Seems to me there is some spin doctoring going on from the authorities. Seems manual trim does not function well at 500 kts plus. I my opinion they forgot the first rule - "fly the f'ing aeroplane".

https://youtu.be/HBqDcUqJ5_Q
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Last edited by valleyboy on Wed Apr 10, 2019 6:08 am, edited 6 times in total.

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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by BTD » Wed Apr 10, 2019 7:42 am

valleyboy wrote:
Wed Apr 10, 2019 6:02 am
I came across this and it seems to be the be pretty authentic and good delivery. It is getting "thumbs up" from 73 max pilots. I'm not sure how he got his information but it sure disputes the announcement that the crew reacted and followed the proper procedures. Seems to me there is some spin doctoring going on from the authorities. Seems manual trim does not function well at 500 kts plus. I my opinion they forgot the first rule - "fly the f'ing aeroplane".

https://youtu.be/HBqDcUqJ5_Q
He got his information from the preliminary report. He didn’t mention that the stickshaker was going the entire time. I watched this the other day, and overall he does a good job. The report is missing some information, but it is enough to know that the crew did not do everything perfectly, but they did enough and then had to start thinking outside the box. I’ll quote my own post from above.
BTD wrote:
Fri Apr 05, 2019 8:50 pm
We have all read and seen the accident reports of a competent crew flying a perfectly good airplane into the ground. It has happened so many times in the last 50 years. Human factor considerations are usually involved in some form or another. Things we are all susceptible to.

Now we have an aircraft that develops a fault that takes you 90% of the way to the crash then demands that you do a procedure perfectly in a very short period of time all while throwing as many distractions at you that the airplane can think of. And even then you may have to do a little fancy foot work to get out of it by reading between the lines of the provided QRH procedure. Good luck. And it does this almost by design.

Remember a few min before, these guys were probably thinking of where they were going to eat dinner that night. Not planning for the fight of their life.

Btd
Have you ever been part of or watched an unanticipated go around either in the sim or in real life? It rarely goes smoothly. Now here is a scenario the crew had not been trained for aside from some documentation, and the only thing they missed was auto throttle Disengage. Uh oh, surprise the manual trim is jammed.

Based on the report so far it seems all the crew were trying to do was “fly the airplane” given all the other distractions.

However, our perspective on this could change with more data.

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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by Heliian » Wed Apr 10, 2019 7:46 am

valleyboy wrote:
Wed Apr 10, 2019 6:02 am
I came across this and it seems to be the be pretty authentic and good delivery. It is getting "thumbs up" from 73 max pilots. I'm not sure how he got his information but it sure disputes the announcement that the crew reacted and followed the proper procedures. Seems to me there is some spin doctoring going on from the authorities. Seems manual trim does not function well at 500 kts plus. I my opinion they forgot the first rule - "fly the f'ing aeroplane".

https://youtu.be/HBqDcUqJ5_Q
He got his "information" from the internet. It's in the video description. I didn't bother to watch the whole 25 minutes but the general consensus is that they were following procedures. If you believe his hordes of fake subscribers.
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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by valleyboy » Wed Apr 10, 2019 8:31 am

to watch the whole 25 minutes but the general consensus is that they were following procedures. If you believe his hordes of fake subscribers

He did say that they did get the cut out switches to "cut out" but it is obvious the crew was not paying attention to flying the aircraft since they never reduced the thrust. If they had only controlled their airspeed the results might have been different. If you exceed design limitations(over 500 kts) can you depend on set emergency procedures to work.

I'm not saying Boeing should be exonerated but I don't think they are a 100% to blame either. There has to be a certain expectation for a crew to be able to at least try and fly the aircraft with in design structural limitations if at all possible.

I was give an exercise in the sim once where an engine went to "radar" thrust on rotation. This was never a normal sim failure, it was always a loss of power. It was an eye opener. I was a 300 kts before I knew it, with good engines retarded. I know how just being distracted for an instant can put you in an excessive airspeed situation. In the Boeing world of the past targeted airspeeds were expected in every flight regime. I doubt that has changed.
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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by BTD » Wed Apr 10, 2019 9:26 am

valleyboy wrote:
Wed Apr 10, 2019 8:31 am
to watch the whole 25 minutes but the general consensus is that they were following procedures. If you believe his hordes of fake subscribers

He did say that they did get the cut out switches to "cut out" but it is obvious the crew was not paying attention to flying the aircraft since they never reduced the thrust. If they had only controlled their airspeed the results might have been different. If you exceed design limitations(over 500 kts) can you depend on set emergency procedures to work.

I'm not saying Boeing should be exonerated but I don't think they are a 100% to blame either. There has to be a certain expectation for a crew to be able to at least try and fly the aircraft with in design structural limitations if at all possible.

I was give an exercise in the sim once where an engine went to "radar" thrust on rotation. This was never a normal sim failure, it was always a loss of power. It was an eye opener. I was a 300 kts before I knew it, with good engines retarded. I know how just being distracted for an instant can put you in an excessive airspeed situation. In the Boeing world of the past targeted airspeeds were expected in every flight regime. I doubt that has changed.
My interpretation is that they were so consumed with flight path control given the flight control malfunction they were task saturated and there was limited congnative resources left over. Now we can say with 5 and 1 months hindsight they should have done this, but in those 5 mins or so of flight the human factors side of this is huge. Attention is a limited resource and if most if it is take up by just keeping the blue side up it isn’t suprising they missed some things.

It is interesting to watch pick pocket videos on YouTube. Even on a stage show where the person has said they are going to do such and such, and we are watching on a screen from the comfort of our living room, we will often miss the move they do because they control your limited attention away from what they don’t want us to see
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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by RVR6000 » Wed Apr 10, 2019 5:43 pm

On a recurrent sim brief the crew on the usual RTO, v1 cut, engine fires and failures. Then give this etiopian scenario on the first go, it would be interesting to know the success rate.

Lion air guys didn’t even know MCAS existed, imagine being thrown into this without any knowledge of such a powerful system. Nothing short of negligence on part of Boeing, 346 lives lost to keep a common type rating and to beat the 320NEO to market.
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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by jakeandelwood » Wed Apr 10, 2019 8:49 pm

Of course if you give any 737 pilot this situation in the sim now they are going to be able to figure it out, they are all well aware of it. They may even be half expecting it from now on when they do sim training.
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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by complexintentions » Fri Apr 12, 2019 3:26 pm

RVR6000 wrote:
Wed Apr 10, 2019 5:43 pm
On a recurrent sim brief the crew on the usual RTO, v1 cut, engine fires and failures. Then give this etiopian scenario on the first go, it would be interesting to know the success rate.

Lion air guys didn’t even know MCAS existed, imagine being thrown into this without any knowledge of such a powerful system. Nothing short of negligence on part of Boeing, 346 lives lost to keep a common type rating and to beat the 320NEO to market.
I'd like to think that if they were given this bulletin that all Ethiopian crews were given, any regular crew would be able to survive the situation. The bulletin is very, very clear and explicit - if I got a stick-shaker right after takeoff when all else was normal, and I could look outside and see I was climbing and accelerating it would be the first thing I would suspect, after reading this and knowing of the Lion Air crash. The bulletin even states "This bulletin directs crews to EXISTING procedures to address this condition."

I don't think I'd be engaging - or attempting to engage - the autopilot, which was one of the first things the Ethiopian crew did at 400 ft. That isn't the correct procedure for either unreliable airspeed or a stall. The Runaway Stabilizer procedure also states in part "ensuring that the STAB TRIM CUTOUT switches are set to CUTOUT and stay in the CUTOUT position for the remainder of the flight". The FDR shows that the switches were cutout then reengaged later. Which is why the Ethiopian authorities stating that the crew "followed all procedures correctly" is suspect. According to their own report, they did not.

Yes, it's easy to be accused of armchair quarterbacking but at some point pilots need to Fly The Airplane.

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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by Rockie » Sun Apr 14, 2019 7:38 pm

You weren’t there Complex. Don’t destroy what respect I have for you by speculating what you would, or would not have done. I can’t, so you can’t. Exit this discussion.
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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by Eric Janson » Sun Apr 14, 2019 8:52 pm

A different perspective on the Boeing company...

https://www.youtube.com/watch?v=706KmH5Fg_Y
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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by geodoc » Mon Apr 15, 2019 11:11 am

Here's a grim litany of the government / industry / lobby shop nexus that was likely at the root of the problem:

https://www.seattletimes.com/business/b ... mpaign=ios


.
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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by av8ts » Mon Apr 15, 2019 12:04 pm

Rockie wrote:
Sun Apr 14, 2019 7:38 pm
You weren’t there Complex. Don’t destroy what respect I have for you by speculating what you would, or would not have done. I can’t, so you can’t. Exit this discussion.
Wait!! What!! You’ve decided that other people are not allowed to speculate on what they would or would not have done.
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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by Gino Under » Mon Apr 15, 2019 1:34 pm

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Re: Ethiopian Airlines: 'No survivors' on crashed Boeing 737 max

Post by Ki-ll » Tue Apr 16, 2019 4:19 am

geodoc wrote:
Mon Apr 15, 2019 11:11 am
Here's a grim litany of the government / industry / lobby shop nexus that was likely at the root of the problem:

https://www.seattletimes.com/business/b ... mpaign=ios


.
That’s a good article.
I like how they mentioned airline engineering departments at the end. Are there any true engineering departments left anywhere? Somehow I feel like they’d be one of the first victims of cost cutting.
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