Ethiopian Airlines 737 Max crashes killing 157

[Dbeasy 14961]

Not disagreeing with what the pilots have to say, however I didn’t fully explain. When in a typical flight angle, the difference is minimal and not that big of a deal. The problem is when the angle of attack changes significantly due to the software pitching the nose far down. At that point the responsiveness could be very different (angle and thrust vector math). That’s where the Ethiopian pilots ran into issues. Of course these pilots made the error of turning the system back on as well. Would be interesting to hear whether pilots who fly it and trained for it saw much difference in the simulators or in the air when the angle of attack was shoved downward quickly.

[Bobby_Batronic 1994]

5 hours ago, JimmyJames said:

Exactly. What I’m having a problem with is multiple posters in this thread blaming the pilots, then when someone points to something that blames Boeing, the retort becomes “we need to wait until the investigation is completed.” It’s hypocritical as shit and annoying. 

I personally am neither a pilot or an airplane engineer, but I have a brain, common sense, and an opinion. And that opinion is that Boeing majorly fucked up this design. And my evidence?

Hundreds of people dead in a six month period and an entire fleet of very expensive airplanes grounded costing companies billions of dollars. 

Hell that might be worth an internet post here or there. 

 

 

You need to work on your reading comp, because that’s not remotely what was said. CNN ran with a half true headline. Why?  Probably because they wanted a splash headline, don’t understand the subject matter and know their audience doesn’t either. 

If you’ve read this thread then you’d see that the pilots in this thread have posted that the whole thing was borked from inception, but also that the crews screwed up. I’ve read the preliminary report from the Ethiopian crash. Both pilots initially correctly reacted to the situation, and both called out the correct AOA vane failure. They also managed to manually trim the wrong way at one point, turned the system back on, and were flying so far past the aircrafts maximum speed after never retarding the thrust levers until the last 15 seconds of the flight that the Hulk would have struggled to move the trim wheel under that airload. 

Which is why I say we’re gonna have to wait at this point, because the press isn’t overly interested in accurately representing the story, and they’re making conflicting statements every day. And not a small part of that is they don’t know what they’re talking about.

 

[JimmyJames 12271]

1 minute ago, Bobby_Batronic said:

You need to work on your reading comp, because that’s not remotely what was said. CNN ran with a half true headline. Why?  Probably because they wanted a splash headline, don’t understand the subject matter and know their audience doesn’t either. 

If you’ve read this thread then you’d see that the pilots in this thread have posted that the whole thing was borked from inception, but also that the crews screwed up. I’ve read the preliminary report from the Ethiopian crash. Both pilots initially correctly reacted to the situation, and both called out the correct AOA vane failure. They also managed to manually trim the wrong way at one point, turned the system back on, and were flying so far past the aircrafts maximum speed after never retarding the thrust levers until the last 15 seconds of the flight that the Hulk would have struggled to move the trim wheel under that airload. 

Which is why I say we’re gonna have to wait at this point, because the press isn’t overly interested in accurately representing the story, and they’re making conflicting statements every day. And not a small part of that is they don’t know what they’re talking about.

 

How on earth are you able to conclude at this point so definitively that the pilots screwed up. You weren’t there. You dont know exactly what happened or what they were reacting to. And whether anything they did would have fixed anything.

The plane isn’t supposed to nose dive down for no good reason shortly after take off. Correct? Are you willing to at least admit that? Because right now that appears to be all we know for sure.

[JimmyJames 12271]

Why don’t you just go ahead and tell us how you would have saved the plane.

[Bobby_Batronic 1994]

Because I read the preliminary report which had them go outside of their procedures, trim incorrectly and exceed VMO by a comfortable margin. 

Youre having trouble separating pilot error from there also being other links in the accident chain. Both can be true. 

[JimmyJames 12271]

2 minutes ago, Bobby_Batronic said:

Because I read the preliminary report which had them go outside of their procedures, trim incorrectly and exceed VMO by a comfortable margin. 

Youre having trouble separating pilot error from there also being other links in the accident chain. Both can be true. 

So tell us what you would have done that would’ve saved the aircraft from going down.

You can’t and won’t. Because you don’t know.

[Anastasis 23390]

This thread is flying along smoothly. 

Edited April 5, 2019 by Anastasis

[Bobby_Batronic 1994]

5 minutes ago, JimmyJames said:

So tell us what you would have done that would’ve saved the aircraft from going down.

You can’t and won’t. Because you don’t know.

Slowed down to reduce the airload while using manual trim would be my initial guess. 

 

 

[Gil Bang 25894]

10 hours ago, Pasken said:

If this turns out to be the case then it should be a vindication for Boeing and really illustrates the fact on why there is so much automation in planes.  We can't even trust ourselves to turn a knob in the right direction. 

 

Is anyone watching the current season of Air Disasters? One of the most recent episodes had the first officer try to abort a landing because he sensed something was wrong and the pilot physically stopped him and then they crashed in a mountain about 10 seconds later. 

[XYZ 2154]

I saw today that another pilot error was that they kept the thrust at 100% throughout the whole thing. So two errors from what I understand, 1) re-connect the electric trim (which is not part of the prescribed procedure to deal with that situation), and 2) not reduce thrust to make it easier to control the plane

[retread 2951]

siap. Preliminary report for Ethiopian flight.

http://www.ecaa.gov.et/documents/20435/0/Preliminary+Report+B737-800MAX+,(ET-AVJ).pdf

Prelim FDR image (big, so I'll link)

https://i.ibb.co/6RVKTrB/image.png

General overview (link)

https://i.ibb.co/xhBZ7bS/image.png

Edited April 5, 2019 by retread

[Dahobbs 17420]

1 hour ago, XYZ said:

I saw today that another pilot error was that they kept the thrust at 100% throughout the whole thing. So two errors from what I understand, 1) re-connect the electric trim (which is not part of the prescribed procedure to deal with that situation), and 2) not reduce thrust to make it easier to control the plane

Error 1 and 2 seem connected. They noted manual control wasn't possible (I would assume the slight downward change in stabilizer during that time was either from the forces on the stabilizer or from an effort to get the manual wheel "unstuck") and went back to try electric trim again (which may not have worked very well for the same reason based on those other reports). I get that re-connecting electric trim isn't part of procedure, but the procedure wasn't working for them. Now, the reason the procedure wasn't working was probably because of their thrust, but I think that just shows how Boeing's initial guidance was oversimplified. So, maybe some pilot error. But again, the media narrative focused on Boeing's poor decisions seems entirely proper to me. Boeing majorly fucked up. And you know what really emphasized that point for me? After the pilots followed Boeing's guidance and used electric trim to adjust the stabilizer and announced" stab trim cutout", the stupid system Boeing designed sent the command to kill everyone aboard. And we know they followed Boeing's guidance because, at least for the moment, the aircraft didn't follow the suicidal instructions. 

[Fozzz 152]

22 hours ago, Huckleberry said:

22 hours ago, Bobby_Batronic said:

Yes, because reporters always post the unbiased truth, never rush to press with a sensationalist headline and always understand the subject matter they are covering. 
Don’t be a rube. 
Saying “they followed the procedure” when they clearly didn’t follow the procedure is a half truth as Your Mom detailed. It’s like saying you don’t understand why a car went into a ditch after changing a flat tire. I mean you changed the tire. You put the flat back on, but initially you did the right thing by taking it off. 

Eh, no. It would be like if steering assist erroneously detected a non- existent obstacle, started yanking your car hard right toward the edge of a cliff, you turned it off but weren't strong enough to turn the steering wheel back because the steering assist and power steering were linked and either both on or both off, so then you turned it back on hoping you could then overpower the steering assist and force the wheel back. Then you died because an engineering feature that was not strictly necessary in the first place activated when it shouldn't have and created a deadly situation.

Is the driver in this hypothetical American or from some shithole country?

[jkates 313]

12 hours ago, Bobby_Batronic said:

Slowed down to reduce the airload while using manual trim would be my initial guess. 

 

 

What do you mean by "reduce the airload?" 

[bschoolprof 6232]

16 minutes ago, jkates said:

What do you mean by "reduce the airload?" 

Via context clues, I'm guessing slowing the plane down so the forces on the control surfaces (e.g., stabalizer, elevator) are lower and easier to deal with.  

[DaysOff 7843]

Slow down and relax a little back pressure (hard to do close to earth).

[GringoSalado 1651]

^ 

from the Seattle Times article upthread

https://www.seattletimes.com/business/boeing-aerospace/boeings-emergency-procedure-for-737-max-may-have-failed-on-ethiopian-flight/

 

Quote

“The forces on the tail could have been too great,” Lemme said. “They couldn’t turn the manual trim wheel.”

The stabilizer in the Ethiopian jet could have been in an extreme position with two separate forces acting on it:

• MCAS had swiveled the stabilizer upward by turning a large mechanical screw inside the tail called the jackscrew. This is pushing the jet’s nose down.
• But the pilot had pulled his control column far back in an attempt to counter, which would flip up a separate movable surface called the elevator on the trailing edge of the tail.

The elevator and stabilizer normally work together to minimize the loads on the jackscrew. But in certain conditions, the elevator and stabilizer loads combine to present high forces on the jackscrew and make it very difficult to turn manually.

 

[Anastasis 23390]

2 hours ago, retread said:

siap. Preliminary report for Ethiopian flight.

http://www.ecaa.gov.et/documents/20435/0/Preliminary+Report+B737-800MAX+,(ET-AVJ).pdf

Prelim FDR image (big, so I'll link)

https://i.ibb.co/6RVKTrB/image.png

General overview (link)

https://i.ibb.co/xhBZ7bS/image.png

2G into the dirt?  Sound like a hell of a ride. 

Edited April 5, 2019 by Anastasis

[GringoSalado 1651]

The vid of the 737 simulator replicating the "extreme mis-trim" scenario described in the Seattle Times article above has been taken down apparently, in googling around for it I found this:

 

https://leehamnews.com/2019/04/03/et302-used-the-cut-out-switches-to-stop-mcas/

ET302 used the Cut-Out switches to stop MCAS

 

By Bjorn Fehrm

Note: The article offered a Video as an example of the effects of not trimming to neutral before hitting Cut-Off. After reviewing the effects of the video in the context of the article, MentourPilot decided we should leave the text but not include the video any longer. MentourPilot’s YouTube channel is an independent initiative to offer the public correct and positive information of all the work which is behind their safe travel in the skies. In the sensitive situation of an ongoing investigation of the crash of ET302, where not all facts are on the table, he concluded after discussing the impression the video left with a colleague, it was not in line with his intent of setting up the channel. In the haste of the change we took this as his company not wanting the video aired, it was not.  As facts in the ET302 case comes forward we will discuss with MentourPilot if this situation changes. 

April 03, 2019, © Leeham News

Spoiler

The crew of Ethiopian Airlines ET302, which crashed with 157 people on board, used the prescribed Stabilator Trim Cut-Out switches to stop MCAS, according to an article by Wall Street Journaltoday. Yet still, they crashed. We’ve had the information this could indeed be the case for several days, but we didn’t want to speculate in such a sensitive matter.

The Wall Street article cites information coming from the investigation. By it, we can now reveal how it’s possible the aircraft can crash despite using the Cut-Out switches. To verify, we ran it all in a simulator together with MentourPilot Youtube channel over the last days.

Figure 1. ET302 ground speed as long as FlightRadar24 could follow the flight. Source: FR24.

 

Following procedures can create dangerous situations with original MCAS

The aeronautical world was stunned when ET302 went down in what seemed a case similar to Lion Air JT610. “Why didn’t they use the trim Cut-Out switches?” was the reaction from longtime pilots. “Every pilot in the world knew what to do, weren’t they briefed?”

The information around the ET302 crash, which comes forward piece by piece, points to an almost identical chain of events to JT610. It also points to the pilots being briefed and, to the knowledge we have available, following procedures including the procedures for a wild running MCAS.

How could ET302 then crash? The FAA and Boeing issued an Airworthiness Directive 2018-23-51 on 8th of November 2018 on what Emergency checklist to use to avoid another MCAS caused crash? The crew should execute the “Trim runaway” emergency checklist.

So why didn’t it work, if the crew indeed followed this AD? Here’s why:

Two weeks ago I wrote: the flying with a full nose down Horizontal Stabilator trim was possible on a 737. The pilot could control the aircraft with his elevator control via the Yoke, even against a full nose down MCAS trim. This was verified in a 737 simulator by a US airline. At the time, I asked what the flown speed was? The answer I got was; the typical speeds after Taking Off.

In subsequent discussions with MentourPilot, a YouTube channel with millions of viewers, I was informed this would probably not be true for higher speeds. MentourPilot’s experience when examining hundreds of pilots as Type Rating Examiner for the 737 was the elevator got exceedingly heavy at higher speeds and manual trimming at the slightest miss-trim of the Stabilator from neutral Yoke forces was very difficult.

He also pointed out the high speeds observed in ET302’s FlightRadar24 trace (Figure 1) were logical. It’s a consequence of following the Emergency checklist for “IAS disagree” (IAS is Indicated Airspeed, i.e. the dynamic air pressure experienced by the aircraft) after takeoff.

The combination of the preceding checklist followed by an MCAS Trim Runaway checklist could create a situation where manual trimming after a Trim Cut-Out would be difficult to impossible and would require non-checklist actions.

Combined with the speed which follows from an “IAS disagree” Emergency checklist procedure the Pilot Monitoring (PM) could have problems to move the trim while Pilot Flying (PF) would fight to hold the Yoke against the elevator forces. At a larger miss-trim, the situation is unattainable.

The excessive manual trim forces have been confirmed by an airline pilot which has done 737 test flights after elevator maintenance, where manual trimming needs to be checked. At a miss-trimmed Stabilator, you either have to re-engage Electric trim or off-load the Stabilator jackscrew by stick forward, creating a nose-down bunt maneuver, followed by trim.

Stick forward to trim was not an option for ET302, they were at 1,000ft above ground. According to The Wall Street Journal, the ET302 crew re-engaged electrical trim to save the situation, to get the nose up. It was their only chance. But too late. The aggressive MCAS kicked in and worsened the situation before they could counter it.

Conclusions

We refrain from speculating more on the limited information we have available. What exactly happened in ET302 will be revealed by the preliminary report, which should be issued within days.

We now know that if the Wall Street article and the rumors are correct, the Trim Cut-Out switches were used by the ET302 crew.

We also know the execution of the Trim Runaway checklist as described in the Emergency Airworthiness Directive (AD) did not describe all the consequences of a trim Cut-Out after an MCAS cycle. Here the text from the AD:

In the event an uncommanded nose down stabilizer trim is experienced on the 737-8/-9, in conjunction with one or more of the indications or effects listed below, do the existing AFM Runaway Stabilizer procedure above ensure that the STAB TRIM CUTOUT switches are set to CUTOUT and stay in the CUTOUT position for the remainder of the flight?

An erroneous AOA input can cause some or all of the following indications and effects:

• Continuous or intermittent stick shaker on the affected side only.
• Minimum speed bar (red and black) on the affected side only.
• Increasing nose down control forces.
• IAS DISAGREE alert.
• ALT DISAGREE alert.
• AOA DISAGREE alert (if the option is installed).
• FEEL DIFF PRESS light.
• Autopilot may disengage.
• Inability to engage autopilot.

 Initially, higher control forces may be needed to overcome any stabilizer nose down trim already applied. Electric stabilizer trim can be used to neutralize control column pitch forces before moving the STAB TRIM CUTOUT switches to CUTOUT. Manual stabilizer trim can be used before and after the STAB TRIM CUTOUT switches are moved to CUTOUT.

Nowhere is it described the trim could be impossible to move if the Cut-Out switches were cut at the slightest miss-trim at the speeds flown. And there is no warning on when to move the Cut-Out switches, the checklist says “Cut, then trim manually.” This is not the whole truth.

What exactly happened will be known once the preliminary report is there. Today we know the crowing from Western pilots, “Typical third world crews,” was not called for. Anyone who has tried a correctly set up MCAS situation in a simulator is more muted.

PS. Regarding blowback of the Elevator, can this come into play as I wrote about here? With the information added by MentourPilot the situation seems to get unattainable before a blowback comes into play. We will know more once the ET302 preliminary report is here. DS

 

Edited April 5, 2019 by GringoSalado

[Pasken 1309]

 

1 hour ago, Dahobbs said:

Error 1 and 2 seem connected. They noted manual control wasn't possible (I would assume the slight downward change in stabilizer during that time was either from the forces on the stabilizer or from an effort to get the manual wheel "unstuck") and went back to try electric trim again (which may not have worked very well for the same reason based on those other reports). I get that re-connecting electric trim isn't part of procedure, but the procedure wasn't working for them. Now, the reason the procedure wasn't working was probably because of their thrust, but I think that just shows how Boeing's initial guidance was oversimplified. So, maybe some pilot error. But again, the media narrative focused on Boeing's poor decisions seems entirely proper to me. Boeing majorly fucked up. And you know what really emphasized that point for me? After the pilots followed Boeing's guidance and used electric trim to adjust the stabilizer and announced" stab trim cutout", the stupid system Boeing designed sent the command to kill everyone aboard. And we know they followed Boeing's guidance because, at least for the moment, the aircraft didn't follow the suicidal instructions. 

 

They spent 4 minutes above the listed max velocity for the plane. There was plenty of time to slow the fuck down.  They didn't even start losing altitude until after they turned the automatic system back on in the last 30 seconds of the flight. They were in danger but they were not flying toward the earth until they broke procedure and turned the system back on.

Edited April 5, 2019 by Pasken

[Dahobbs 17420]

42 minutes ago, Pasken said:

 

 

They spent 4 minutes above the listed max velocity for the plane. There was plenty of time to slow the fuck down.  They didn't even start losing altitude until after they turned the automatic system back on in the last 30 seconds of the flight. They were in danger but they were not flying toward the earth until they broke procedure and turned the system back on.

I agree it appears they should have slowed down. I don't see how that invalidates my broader point: the focus on Boeing is appropriate as Boeing's fuck up is magnitudes worse than the pilots.   

[Bobby_Batronic 1994]

2 hours ago, Dahobbs said:

Error 1 and 2 seem connected. They noted manual control wasn't possible (I would assume the slight downward change in stabilizer during that time was either from the forces on the stabilizer or from an effort to get the manual wheel "unstuck") and went back to try electric trim again (which may not have worked very well for the same reason based on those other reports). I get that re-connecting electric trim isn't part of procedure, but the procedure wasn't working for them. Now, the reason the procedure wasn't working was probably because of their thrust, but I think that just shows how Boeing's initial guidance was oversimplified. So, maybe some pilot error. But again, the media narrative focused on Boeing's poor decisions seems entirely proper to me. Boeing majorly fucked up. And you know what really emphasized that point for me? After the pilots followed Boeing's guidance and used electric trim to adjust the stabilizer and announced" stab trim cutout", the stupid system Boeing designed sent the command to kill everyone aboard. And we know they followed Boeing's guidance because, at least for the moment, the aircraft didn't follow the suicidal instructions. 

Of course it sent the message to pitch down. That’s it’s whole purpose. Again, the Airbus will do the same damn thing. It has more redundancy because there’s a computer between the pilot and flight controls until you get to the fourth level of backup, but it too will tell the plane to pitch down in such a situation until you turn some features off. Even then, it will still tell the plane to pitch over, but in Alternate Law that pitch command is overridable with stick input. 

I'm not arguing that Boeing didn’t make huge mistakes aided by our friends in the FAA. I didn’t know single source data was an option when this all went down. 

[retread 2951]

Narrative from Republic of Ethiopia's Prelim Report

http://www.ecaa.gov.et/documents/20435/0/Preliminary+Report+B737-800MAX+,(ET-AVJ).pdf

Quote

1 FACTUAL INFORMATION

1.1 HISTORY OF FLIGHT

On March 10, 2019, at about 05:44 UTC1, Ethiopian Airlines flight 302, a Boeing 737-8 (MAX), Ethiopian registration ET-AVJ, crashed near Ejere, Ethiopia, shortly after takeoff from Addis Ababa Bole International Airport (HAAB), Ethiopia. The flight was a regularly scheduled international passenger flight from Addis Ababa to Jomo Kenyatta International Airport (HKJK), Nairobi, Kenya. There were 157 passengers and crew on board. All were fatally injured, and the Aircraft was destroyed.

The following is based on the preliminary analysis of the DFDR, CVR and ATC communications. As the investigation continues, revisions and changes may occur before the final report is published.

At 05:37:34, ATC issued take off clearance to ET-302 and to contact radar on 119.7 MHz.

Takeoff roll began from runway 07R at a field elevation of 2333.5 m at approximately 05:38, with a flap setting of 5 degrees and a stabilizer setting of 5.6 units. The takeoff roll appeared normal, including normal values of left and right angle-of-attack (AOA). During takeoff roll, the engines stabilized at about 94% N1, which matched the N1 Reference recorded on the DFDR. From this point for most of the flight, the N1 Reference remained about 94% and the throttles did not move.

The N1 target indicated non data pattern 220 seconds before the end of recording. According to the CVR data and the control column forces recorded in DFDR, captain was the pilot flying.

At 05:38:44, shortly after liftoff, the left and right recorded AOA values deviated. Left AOA decreased to 11.1° then increased to 35.7° while value of right AOA indicated 14.94°. Then after, the left AOA value reached 74.5° in ¾ seconds while the right AOA reached a maximum value of 15.3°.

At this time, the left stick shaker activated and remained active until near the end of the recording.

Also, the airspeed, altitude and flight director pitch bar values from the left side noted deviating from the corresponding right side values. The left side values were lower than the right side values until near the end of the recording.

At 05:38:43 and about 50 ft radio altitude, the flight director roll mode changed to LNAV.

At 05:38:46 and about 200 ft radio altitude, the Master Caution parameter changed state. The First Officer called out Master Caution Anti-Ice on CVR. Four seconds later, the recorded Left AOA Heat parameter changed state.

At 05:38:58 and about 400 ft radio altitude, the flight director pitch mode changed to VNAV SPEED and Captain called out “Command” (standard call out for autopilot engagement) and an autopilot warning is recorded.

At 05:39:00, Captain called out “Command”.

At 05:39:01 and about 630 ft radio altitude, a second autopilot warning is recorded.

1

All times listed is Universal Coordinated Time (UTC), as recorded on the FDR. Aircraft Accident Investigation Bureau Preliminary Report March, 2019 10 of 33

At 05:39:06, the Captain advised the First-Officer to contact radar and First Officer reported SHALA 2A departure crossing 8400 ft and climbing FL 320.

Between liftoff and 1000 ft above ground level (AGL), the pitch trim position moved between 4.9 and 5.9 units in response to manual electric trim inputs. At 1000 ft AGL, the pitch trim position was at 5.6 units.

At 05:39:22 and about 1,000 feet the left autopilot (AP) was engaged (it disengaged about 33 seconds later), the flaps were retracted and the pitch trim position decreased to 4.6 units.

Six seconds after the autopilot engagement, there were small amplitude roll oscillations accompanied by lateral acceleration, rudder oscillations and slight heading changes. These oscillations continued also after the autopilot was disengaged.

At 05:39:29, radar controller identified ET-302 and instructed to climb FL 340 and when able right turns direct to RUDOL and the First-Officer acknowledged.

At 05:39:42, Level Change mode was engaged. The selected altitude was 32000 ft. Shortly after the mode change, the selected airspeed was set to 238 kt.

At 05:39:45, Captain requested flaps up and First-Officer acknowledged. One second later, flap handle moved from 5 to 0 degrees and flaps retraction began.

At 05:39:50, the selected heading started to change from 072 to 197 degrees and at the same time  the Captain asked the First-Officer to request to maintain runway heading.

At 05:39:55, Autopilot disengaged,

At 05:39:57, the Captain advised again the First-Officer to request to maintain runway heading and that they are having flight control problems.

At 05:40:00 shortly after the autopilot disengaged, the FDR recorded an automatic aircraft nose

down (AND) activated for 9.0 seconds and pitch trim moved from 4.60 to 2.1 units. The climb was

arrested and the aircraft descended slightly.

At 05:40:03 Ground Proximity Warning System (GPWS) “DON’T SINK” alerts occurred.

At 05:40:05, the First-Officer reported to ATC that they were unable to maintain SHALA 1A and requested runway heading which was approved by ATC.

At 05:40:06, left and right flap position reached a recorded value of 0.019 degrees which remained until the end of the recording. The column moved aft and a positive climb was re-established during the automatic AND motion.

At 05:40:12, approximately three seconds after AND stabilizer motion ends, electric trim (from pilot activated switches on the yoke) in the Aircraft nose up (ANU) direction is recorded on the DFDR and the stabilizer moved in the ANU direction to 2.4 units. The Aircraft pitch attitude remained about the same as the back pressure on the column increased.

At 05:40:20, approximately five seconds after the end of the ANU stabilizer motion, a second instance of automatic AND stabilizer trim occurred and the stabilizer moved down and reached 0.4 units. From 05:40:23 to 05:40:31, three Ground Proximity Warning System (GPWS) “DON’T SINK” alerts occurred.

At 05:40:27, the Captain advised the First-Officer to trim up with him.

At 05:40:28 Manual electric trim in the ANU direction was recorded and the stabilizer reversed moving in the ANU direction and then the trim reached 2.3 units.

At 05:40:35, the First-Officer called out “stab trim cut-out” two times. Captain agreed and FirstOfficer confirmed stab trim cut-out.

At 05:40:41, approximately five seconds after the end of the ANU stabilizer motion, a third instance of AND automatic trim command occurred without any corresponding motion of the stabilizer, which is consistent with the stabilizer trim cutout switches were in the ‘’cutout’’ position

At 05:40:44, the Captain called out three times “Pull-up” and the First-Officer acknowledged.

At 05:40:50, the Captain instructed the First Officer to advise ATC that they would like to maintain 14,000 ft and they have flight control problem.

At 05:40:56, the First-Officer requested ATC to maintain 14,000 ft and reported that they are having flight control problem. ATC approved.

From 05:40:42 to 05:43:11 (about two and a half minutes), the stabilizer position gradually moved in the AND direction from 2.3 units to 2.1 units. During this time, aft force was applied to the control columns which remained aft of neutral position. The left indicated airspeed increased from approximately 305 kt to approximately 340 kt (VMO). The right indicated airspeed was approximately 20-25 kt higher than the left.

The data indicates that aft force was applied to both columns simultaneously several times throughout the remainder of the recording.

At 05:41:20, the right overspeed clacker was recorded on CVR. It remained active until the end of the recording.

At 05:41:21, the selected altitude was changed from 32000 ft to 14000 ft.

At 05:41:30, the Captain requested the First-Officer to pitch up with him and the First-Officer acknowledged.

At 05:41:32, the left overspeed warning activated and was active intermittently until the end of the recording.

At 05:41:46, the Captain asked the First-Officer if the trim is functional. The First-Officer has replied that the trim was not working and asked if he could try it manually. The Captain told him to try. At

05:41:54, the First-Officer replied that it is not working.

At 05:42:10, the Captain asked and the First-Officer requested radar control a vector to return and ATC approved.

At 05:42:30, ATC instructed ET-302 to turn right heading 260 degrees and the First-Officer acknowledged.

At 05:42:43, the selected heading was changed to 262 degrees.

At 05:42:51, the First-Officer mentioned Master Caution Anti-Ice. The Master Caution is recorded on DFDR.

At 05:42:54, both pilots called out “left alpha vane”.

At 05:43:04, the Captain asked the First Officer to pitch up together and said that pitch is not enough.

At 05:43:11, about 32 seconds before the end of the recording, at approximately 13,4002 ft, two momentary manual electric trim inputs are recorded in the ANU direction. The stabilizer moved in the ANU direction from 2.1 units to 2.3 units.

At 05:43:20, approximately five seconds after the last manual electric trim input, an AND automatic trim command occurred and the stabilizer moved in the AND direction from 2.3 to 1.0 unit in approximately 5 seconds. The aircraft began pitching nose down. Additional simultaneous aft column force was applied, but the nose down pitch continues, eventually reaching 40° nose down.

The stabilizer position varied between 1.1 and 0.8 units for the remainder of the recording.

The left Indicated Airspeed increased, eventually reaching approximately 458 kts and the right

Indicated Airspeed reached 500 kts at the end of the recording. The last recorded pressure altitude was 5,419 ft on the left and 8,399 ft on the right.

 

Edited April 5, 2019 by retread

[Bobby_Batronic 1994]

2 hours ago, DaysOff said:

Slow down and relax a little back pressure (hard to do close to earth).

It is. I think they were at roughly 1000 agl as the departure airport is high. Or maybe they made it to 5000ish. The trend line just says pressure altitude which makes me think 1000. Still, they were there for several minutes. (Edit: saw 5000 Rad Alt on the right side of the column)  

I had a total electrical failure once just after we cleaned up on takeoff at 400 agl.  Something about the way the batteries were grounded to the oil pan via the flagillator or something. Regardless, total failure and there were memory items. Engines, backup gauges and over head light were working. The trim was completely electric and frozen. It wasn’t hard to figure out what had happened, but the control forces were tremendous as we accelerated. Strong enough that I couldn’t fly and do the memory items. So I told my partner to,  he was a little taken aback and kinda had to be prodded in the right direction. It finally dawned on me to slow down and we went from massive WTF to a nice arm workout while we reestablished power via the procedure. 

Again, that’s not Superman pilot stuff. But it probably was more likely to occur to us than a 200 hour guy. That may not have saved the day here. Monday morning QBing is easy. But as a pilot it’s easier to see and wonder about the link in the accident that we know best. 

Edited April 5, 2019 by Bobby_Batronic

[Bobby_Batronic 1994]

19 minutes ago, Dahobbs said:

I agree it appears they should have slowed down. I don't see how that invalidates my broader point: the focus on Boeing is appropriate as Boeing's fuck up is magnitudes worse than the pilots.   

Pilot error will be a part of both reports even though Boeing will take it with NLAA over this mistake. The Lion Air crash was under control as the CA re-trimmed 21 times with the electric trim and the plane only crashed when they exchanged controls and the FO failed to. 

[Dahobbs 17420]

21 minutes ago, Bobby_Batronic said:

Of course it sent the message to pitch down. That’s it’s whole purpose. Again, the Airbus will do the same damn thing. It has more redundancy because there’s a computer between the pilot and flight controls until you get to the fourth level of backup, but it too will tell the plane to pitch down in such a situation until you turn some features off. Even then, it will still tell the plane to pitch over, but in Alternate Law that pitch command is overridable with stick input. 

I'm not arguing that Boeing didn’t make huge mistakes aided by our friends in the FAA. I didn’t know single source data was an option when this all went down. 

I'm not sure why my comment appears to be generating hostility. I'm not intending to argue with anyone about this, I'm just trying to discus the issue. I agree, the pilots appear to have messed up. They tried following procedure, but because they kept the speed up, the procedure didn't work. That's partly on them and partly on Boeing for largely dismissing the first incident as complete pilot error and issuing incomplete guidance.

My point about the computer telling the plane to kill everyone aboard was just for dramatic emphasis; it was not supposed to be a surprising fact.  Ultimately, both these incidents occurred because Boeing had a stupid design with a single point of failure that could completely overpower a pilot's control. And the procedures Boeing recommended to correct its error made the plane more difficult to fly and were more difficult to implement than Boeing suggested to the public. Focusing on Boeing in this set of circumstances isn't unreasonable.

I'm all for acknowledging some fault on the pilots. But I don't see any point in villainizing the dead who are unable to defend themselves. Let's learn from their mistakes. But, let's also focus the majority of the blame where it belongs: on the company that tried to cut corners and mislead everyone on the safety of their aircraft. 

Edited April 5, 2019 by Dahobbs

[Bobby_Batronic 1994]

It was hard to tell your point was only for dramatic effect. It appeared that you didn’t understand why the computer would continue to do its only function. 

[Dahobbs 17420]

3 minutes ago, Bobby_Batronic said:

It was hard to tell your point was only for dramatic effect. It appeared that you didn’t understand why the computer would continue to do its only function. 

Got ya. The chain of events just resonates with me emotionally and underscores why Boeing is, in my mind, the primary culprit here. That is all. I understand why the computer did what it did. 

[Pato del Muerto 52336]

Is it normal to have a plane at 100% thrust?   Even at takeoff?  Seems akin to flooring your car. Should be pretty rare under normal conditions, otherwise the thing is underpowered, and those nice new jet engines probably aren’t underpowered. 

[Pato del Muerto 52336]

And if we are talking about the AoA sensor as the single point of failure, the system wasn’t engineered that way. Someone at Boeing decided that the engineered redundancy for that system/sensor should be offered as an add on, either to make the “sales price” look better when they assumed all airlines would pay for the redundancy, or to get more sales from lower prices. 

Does this plane have a cargo variant, where they might only be risking 3 pilot lives who should be able to save the plane themselves, such that the risk is low enough to justify a single AoA sensor?  

And maybe that was the intention, but Boeing allowed passenger carrier orders as such?

[Bobby_Batronic 1994]

16 minutes ago, Pato del Muerto said:

Is it normal to have a plane at 100% thrust?   Even at takeoff?  Seems akin to flooring your car. Should be pretty rare under normal conditions, otherwise the thing is underpowered, and those nice new jet engines probably aren’t underpowered. 

Planes take off at less than full power all the time. This is known as a Flex takeoff. There’s still enough performance to meet regulatory requirements and it’s easy on the motors too.

TOGA (max power) takeoffs do happen. It really depends on the conditions. The departure airport had a high elevation so perhaps they were using a TOGA setting. 

Part of the crux of the problem is that Boeing offered dual sourcing as an option and the airlines purchased the plane this way. 

[TornACL 7674]

"Ohhh, you wanted the non-crashing model? Sorry that's a higher trim package, that's available as a standard feature in our PULL UP PULL UP model."

 

 

[Dahobbs 17420]

35 minutes ago, Pato del Muerto said:

And if we are talking about the AoA sensor as the single point of failure, the system wasn’t engineered that way. Someone at Boeing decided that the engineered redundancy for that system/sensor should be offered as an add on, either to make the “sales price” look better when they assumed all airlines would pay for the redundancy, or to get more sales from lower prices. 

Does this plane have a cargo variant, where they might only be risking 3 pilot lives who should be able to save the plane themselves, such that the risk is low enough to justify a single AoA sensor?  

And maybe that was the intention, but Boeing allowed passenger carrier orders as such?

It is still a single point of failure. The options just give you better notice that there is a discrepancy between the two AoA sensors. MCAS itself takes input only from one of those sensors in all builds of plane. I really am shocked that any engineer would have signed off on that sort of system. At minimum you'd expect MCAS to shutoff in the event of a substantial variance between the two sensors, especially given the amount of authority it has over the stabilizer. I also question why you'd make the primary method of disabling MCAS also disable the best controls for the stabilizer (manual electronic trim). Why not have a software only method as the primary with the secondary being physical cutoff? 

Edited April 5, 2019 by Dahobbs

[Anastasis 23390]

BA cutting 737 max production. 

[RPM 26208]

1 hour ago, Bobby_Batronic said:

Part of the crux of the problem is that Boeing offered dual sourcing as an option and the airlines purchased the plane this way. 

And this one point why I keep crying bean counters. Critical safety features shouldn't be optional. You know it could be a problem, you have a solution, put it on every plane and roll in the cost. It's not like an upgrade for rich Corinthian leather seats.

[Bobby_Batronic 1994]

3 minutes ago, RPM said:

And this one point why I keep crying bean counters. Critical safety features shouldn't be optional. You know it could be a problem, you have a solution, put it on every plane and roll in the cost. It's not like an upgrade for rich Corinthian leather seats.

As an aside you’ll  be happy to know that these events are driving healthy discussions in flying communities about how a given plane would respond in a similar situation, and furthering the understanding of the automation. 

[retread 2951]

And this one point why I keep crying bean counters. Critical safety features shouldn't be optional. You know it could be a problem, you have a solution, put it on every plane and roll in the cost. It's not like an upgrade for rich Corinthian leather seats.

You just have to hope your airline got the Eddie Bauer edition

[C-Man 27029]

Any theories on why the AOA sensor malfunctioned in the first place? Does that happen more often than I really want to know?

[bschoolprof 6232]

3 minutes ago, C-Man said:

Any theories on why the AOA sensor malfunctioned in the first place? Does that happen more often than I really want to know?

I read somewhere they think it happened on takeoff - bird or debris strike.  

[ztejas 43262]

31 minutes ago, retread said:

45 minutes ago, RPM said:

And this one point why I keep crying bean counters. Critical safety features shouldn't be optional. You know it could be a problem, you have a solution, put it on every plane and roll in the cost. It's not like an upgrade for rich Corinthian leather seats.

You just have to hope your airline got the Eddie Bauer edition

I only fly Batchelor edition with twinkies and a bitching sound system

[tucker 238]

4 hours ago, C-Man said:

Any theories on why the AOA sensor malfunctioned in the first place? Does that happen more often than I really want to know?

Even pilots ignore the check engine light, because it is always some bs sensor! 

Edited April 6, 2019 by tucker

[Onboard 2.0 9083]

23 hours ago, Anastasis said:

This thread is flying along smoothly. 

coffee ??, tea ??, mace ??

[Onboard 2.0 9083]

5 hours ago, Bobby_Batronic said:

As an aside you’ll  be happy to know that these events are driving healthy discussions in flying communities about how a given plane would respond in a similar situation, and furthering the understanding of the automation. 

Illustrating the old axiom, beautifully... ya gotta break a few eggs too make an omelette.

[DaysOff 7843]

Any theories on why the AOA sensor malfunctioned in the first place? Does that happen more often than I really want to know?

This is the crux of the issue. MCAS responded as designed. I've been on the airplane 15 years and never heard of an AoA vane failing. Its simplicity makes it damn near fail safe outside of being hit by a Turkey vulture. Did a bad batch roll of ths assembly line one day?

[HoustonHorn 1059]

The point of engineering is that there aren't errors.

That doesn't remove the responsibility. Shifting responsibility to humans to make very quick life and death decisions because you're design is wrong is not engineering.

And I don't mean that as a fault to anyone here who are obviously well trained and fully able to make decisions as a pilot. I'm sure you have the requisite training and your insight as to what happened and why it's easily preventable is welcome.

Still shitty engineering. Now is that due to shitty engineers, shitty accountants or shitty management. Maybe we'll find out. Maybe we won't.

I don’t have time to get into it as I’m about to trust a bunch of flight computers, but I have said several times, in this thread, in reply to you in fact that there was a chain or errors and that engineering was certainly involved. 
Just as pilot error was involved. Have to go.  
 

[Bobby_Batronic 1994]

Yeah ok. I think you latched onto one word. The FAA f’d up by abdicating certification to Boeing. Boeing f’d up by allowing MCAS to be a single source option instead of dual sources with comparator. The airlines f’d up by buying single sourced safety features.  And it looks like the pilots f’d up a couple of ways too. That’s the point of an accident chain. Any broken link stops the accident, but failure happens at every link. 

[Dbeasy 14961]

Yeah ok. I think you latched onto one word. The FAA f’d up by abdicating certification to Boeing. Boeing f’d up by allowing MCAS to be a single source option instead of dual sources with comparator. The airlines f’d up by buying single sourced safety features.  And it looks like the pilots f’d up a couple of ways too. That’s the point of an accident chain. Any broken link stops the accident, but failure happens at every link. 

This. It required a combination of several bad decisions. Boeing should never have offered the single source. Airlines should never have bought it. Pilots should have trained better, etc

[Pasken 1309]

So there is no way to change the input of the MCAS to the copilot’s sensors? 

[Homercles 10205]

My understanding is that the pilots did NOT follow the procedure properly...they kept switching it on and off. The pilots on the prior flight (can’t remember Lion or Ethiopian) did follow the right procedure, killing the electron trim and completing the flight using the trim wheels, and had no issues.

Boeing will have plenty of liability here, but I’m with Bobby in that it’s a chain of failures...like pretty much every accident

[Brisketexan 104537]

Yeah ok. I think you latched onto one word. The FAA f’d up by abdicating certification to Boeing. Boeing f’d up by allowing MCAS to be a single source option instead of dual sources with comparator. The airlines f’d up by buying single sourced safety features.  And it looks like the pilots f’d up a couple of ways too. That’s the point of an accident chain. Any broken link stops the accident, but failure happens at every link. 

My understanding is that the pilots did NOT follow the procedure properly...they kept switching it on and off. The pilots on the prior flight (can’t remember Lion or Ethiopian) did follow the right procedure, killing the electron trim and completing the flight using the trim wheels, and had no issues.  

Boeing will have plenty of liability here, but I’m with Bobby in that it’s a chain of failures...like pretty much every accident

 

This.

 

And way back early in this thread, that’s what I was trying to communicate. I love failure analysis. It’s fascinating. In complex systems (as most modern aircraft are), it almost always is a chain of failures, and the removal of any link prevents the failure.

 

That means a couple of things. First, we are REGULARLY in a chain of failure that could result in catastrophe. But, the redundancies/safeties almost always work, and break the chain. You don’t know how many flights you’ve been on (as one example) that COULD have crashed, but didn’t, because the safeties/training/etc engaged and quickly broke the chain.

 

The other thing it means is that while every element is critical, the LAST element I want to count on is a human being under immense pressure in a timeframe limited to seconds/minutes. If we’re counting on a human being in a life or death situation to follow an even remotely complex process, that’s a bad plan. The EASIEST place to address the issue is on the ground, with proper engineering and maintenance procedures. Thus, it is there that failures are more inexcusable.

 

Designing an aircraft that will occasionally act in a way that it requires truly expert piloting to save - when a different engineering approach could address that flaw - is a bad design. Always. I’m not talking about how hard it is to fly a plane if something shears off the stabilizer - you really can’t design around a catastrophic physical failure. I’m talking about something that is part of the ordinary operation and avionics of the aircraft.

 

You shouldn’t design a car that may periodically lurch to the right at 70 mph. Ever. Sure, a good driver may be able to react and save the car. But my aunt Edna also drives, and she’s no Mario Andretti. The car needs to be safe for her, too.

 

There may be pilot error here. But it seems apparent that a design error set them up to fail, and that’s unforgivable.