Originally Posted by Lonestarcaptain

Not the full transcript but where was it that (ET302) they differed from the EMERGENCY AD?

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 lA 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.

(First sentence of AD: Disengage autopilot and control airplane pitch attitude with control column and main electric trim as required.)

At 05:40:35, the First-Officer called out "stab trim cut-out" two times. Captain agreed and First* Officer 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

(Second sentence of AD: If relaxing the column causes the trim to move, set stabilizer trim switches to CUTOUT.)

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.

(Last sentence of AD: If runaway continues, hold the stabilizer trim wheel against rotation and trim the airplane manually.)

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


There’s is more to the transcript and it’s available with a simple Google search.

As for the rest of your points:

1. We all fly airplanes that were not airworthy “yesterday” Mx fixes them and signs them off. Same thing happened here. IF the maintenance manual included MCAS we might be having a different discussion. They followed the manual and returned the aircraft to service. AoA and pitot tubes go bad all the time who would guess that this 737 would be diffrent that the others that that technician had worked on for 25,000 hrs. (Yeah see what i did there) the amount of time isn’t experience it’s the knowledge you gain.

2. No idea what you’re talking about. Maybe stick shaker, AoA disagree, IAS Disagree Alt Disagree? They would have gotten a diff feel light and Speed trim but not until the flaps were retract so not sure what AIRCRAFT CONTROL warnings you’re talking about.

3. See above

4. Can you tell me what kind of training ET has? From what I understand it’s a lot more robust that a lot of US airlines do. (And rightfully so given where they are starting from) Lion Air - I’ll give you that they definitely have some things to improve there, and I was with everyone else the days after the crash thinking oh just another Lion air crash, until Boeing started dancing around MCAS.

5. Lion air pushed hard for Max simulator training along with the Malaysian regulators and others. In MFs words “there is no way Boeing will allow that to happen. They’ll go face to face with any regulators asking for simulator training.” Ethiopian CA (PF) had lots of 737 PIC time. Yes the FO was low time but I refer to the transcript. Does time matter if you did it right? How about the 18 landings at BUR in the last third of the runway? If the crew had lots of 737 time does that make it OK to violate FARs, policy and procedures?


A side note if you look at the flight data from ET302 you’ll notice the AP is engaged the flaps are then retracted at clean up. Before the AP disengage there is a right bank that the AP fights against. It’s only after the pilot disengage the AP to correct the course that MCAS activate. So what was the bank all about? The YD is part of the SMYS system the YD and turn coordinator work with variable rudder deflection based on airspeed. Slower more rudder faster less ruder. On ET302 the AoA heat light illuminated just prior to rotation (possible bird strik). The AoA values swing wildly as the aircraft accelerates and climbs. When you shear off a vain there is a counterweight inside that will act like a pendulum with no vain in the free airstream that counterweight will swing with acceleration or pitch change. This feeds big swings in AoA to the ADIRU and SMYD system. Most likely the YD just didn’t know what to do with these values and was issuing erroneous rudder deflection. (This is one of the main reasons every other regulating body got it right by requiring flight crews to put the CB and will require a stick shaker cutout before the Max10 is certified). These Rudder imputes overloaded the AP and the ET 302 crew was startled with Erroneous airspeed, a stick shaker, an Overspeed clacker and an AP disengagement with a roll to the right. All of that was quickly followed by MCAS activating. As shown above they did exactly what Boeing recommended at the time, just not fast enough.

Originally Posted by RJSAviator76

Lonestar, this report omitted the Ethiopian FO turning the Stab Trim Cutout switches back on.

Here’s an interesting case study of that flight:

https://www.linkedin.com/pulse/boein...hn-cordle-cfa/

Originally Posted by JohnnyBekkestad

No, that was brought up as well. They were unable to get control of the airplane due to the aerodynamics forces that they were about to crash anyway. So they re-engaged them.

Originally Posted by Lonestarcaptain

You’re understanding of MCAS as it functioned at the time is incorrect. MCAS would activate at a high AoA an run until AoA was decreased below a preset value (low Alt roughly 5.0). Use of the Main Elec trim stops MCAS then once Main Elec Trim is no longer commanded 5 sec later MCAS is allowed to run again. If he had not engaged the MAIN Elect trim the Stabilizer would have run the the nose down limit for that phase of flight uninterrupted.

Contrary to you assertion if either crew member had held down the trim switch continually until they were able to get the Stab Trim Cutout selected that would have stopped the movement of the stab. (Unless the were against the column cutout then they would have gotten stab movement in the direction commanded by the Main Elect trim until column force was reduce and they came off the column cutout)

I believe the KC-46 has synthetic airdata used as a tie breaker. Engineers at Boeing are on the record asking for that to have been added to the 737 Max after the MCAS activation window was changed to include low altitude / low airspeed. (I believe at least one engineer quit after a safety meeting over this and another fire warning issue on a different aircraft). Either way including a comparator between the 2 AoA might have required time and money but an updated Safety Risk Assessment should have mandated it. Boeing intentionally did not provide the change in the safety assessment to the FAA. They did explain MCAS to the AEG (aircraft evaluation group) but did not update them with a new Assesment as required or inform them that the MCAS activation parameters had been changed to include low speed stalls. The fix that took them 2 years could have been incorporated in the original plane with minor delays. BOEING chose to cut corners and risk lives. Then they doubled down on it after Lion Aio when they looked at the new data that showed 15 more crashes would be likely in the life of the aircraft. Boeing figured that with a crash every 2 years they could get a fix out before the next one…. They were wrong and it was other peoples lives they were staking their bet on.

Originally Posted by Skeet20

LoneStar,

Thats all interesting, however this very airplane had the exact same thing one day earlier. The only difference was there was a jump seat pilot from a another carrier who obviously recognized what was happening and instructed the crew to cut out the trim switches. The crew then flew the airplane on to its destination. Wrote the same problem up again. So now this problem has been written up 3 different times. A flight control problem, runaway trim. But they just kept flying it. That is not a Boeing problem, that is a Lion Air problem, and the men who kept flying this airplane in a continued un airworthy condition. This is well documented. Interesting you don’t hear anything about it.

Originally Posted by Smooth at FL450

aerodynamic forces because the thrust levers were never reduced from takeoff thrust setting of 94%…no wonder they were going too fast to manually trim

Originally Posted by Lonestarcaptain

They were already in a decent with limited elevator authority. Thrust is secondary for speed that case. Pitch is primary. What that mean is if you can’t fix the speed with pitch the power isn’t going to do much. (That’s why power is the last item on stall recovery, got to fix the pitch first). However going from takeoff thrust to idle would have greatly changed the thrust vector possibly causing a further nose down moment. The opportunity to manage speed with thrust went out the window when the nose dropped more than a few degrees below the horizon.

Originally Posted by Lonestarcaptain

So Ethiopian and Lion Air were very different events. Lion Air NOBODY knew MCAS even existed. Ethiopian there was an Emergency AD, which the crew complied with. Only AFTER they had done everything the AD and checklist provided them did they turn the Cutout switches back on. I wasn’t in the seat and don’t know what their thought process was that led to that but I do know and what the CVR and flight data show is by that point they were out of guidance and the aircraft was still not responding to full nose up elevator due to the extreme mistrim. Maybe pulling power earlier would have helped but buy this point with it aircraft in an accelerated dive thrust is just wishful thinking, gravity is in control. So faced with trying something or hitting the ground, I’m not going to criticize them from doing whatever they throught was needed after the Checklist failed them.

The Lion Air crash, yes they encountered a runaway trim caused by a faulty AoA sensor. Of note they were at cruise power, cruise altitude and cruise trim setting. The time available to the crew to assess, balance, and do was much longer (as demonstrated by the fact that it took long enough for the jumpseater to intervene). I believe the exact write up was Trim malfunction at cruise and IAS disagree. The Maintenance logbook is available to the public through the Lion Air Crash report. Maintenance action was followed per the Boeing Maintenance manual, which made no mention of MCAS or the possibility of an AoA fault. The speed trim system would have been ground checked and the aircraft signed off. I doubt any other maintenance department would do anything different given the information available to them at the time.

No one knowingly flew an aircraft that was un airworthy. It was written up and fixed according to procedures. Would you decline an aircraft that had Mx items cleared?

A runaway stab in a 737 goes from a complete non event to “holly **** what is happening” real quick. If you stop the runaway while you still have positive elevator authority it seems like no big deal. A few seconds later or if you allow the pitch to go below the horizon it’s a completely different animal.

NASA, Boeing, EASA and every major airline that operated the MAX sent pilots to Miami after ET302. Very few could handle MCAS as it was designed. These were NTPS grads, senior test pilots, evaluators etc. If you think it was just a pilot skills issue or political I suggest you search out one of the pilots your airline sent maybe they can explain the felling of helplessness. At cleanup altitude they had about 5 second to asses the runway oversets stick shaker and master caution. If they didn’t get the cutout switch’s in the first 5 seconds they were pitch limited on the elevator authority.

It truly scares me that there are people flying this machine that don’t understand what was wrong with it and what was done to fix it.

Originally Posted by Lonestarcaptain

They were already in a decent with limited elevator authority. Thrust is secondary for speed that case. Pitch is primary. What that mean is if you can’t fix the speed with pitch the power isn’t going to do much. (That’s why power is the last item on stall recovery, got to fix the pitch first). However going from takeoff thrust to idle would have greatly changed the thrust vector possibly causing a further nose down moment. The opportunity to manage speed with thrust went out the window when the nose dropped more than a few degrees below the horizon.