Ethiopian 737 Max 8 crash and Fallout

[Quickstatus]

Boeing is still making the NG (-700, -800, -900)

Unsure if the production is taking new orders.

 

[jb747]

Are they still making NG’s and can operators convert orders across?

Why would you want to?

The MAX was a somewhat desperate response to the A320 NEO. The entire point of it is the reduced fuel burn of the new engines. If an airline wants that efficiency, then the choice is MAX or NEO. NG doesn't come into it.

 

[Saab34]

Probably more for those that are heavy Boeing reliant with a heavy fleet of NG’s that essentially don’t want the MAX anymore. Still more cost efficient for say Virgin to pick up some more NG’s than convert its entire operation to Airbus. MAX does come with a larger price tag also. Lucky for Virgin they are not essentially critical for business expansion or anything, the first dozen were just Tiger fleet swap outs.

Then there is the problem of financial strains from delayed MAX deliveries compared to taking NG’s today. Any MAX efficiency is lost via these frames sitting idle.

Unless Boeing is compensating which is going to start to become a problem as they are about to start producing 57 of these aircraft a month.

Why would you want to?

The MAX was a somewhat desperate response to the A320 NEO. The entire point of it is the reduced fuel burn of the new engines. If an airline wants that efficiency, then the choice is MAX or NEO. NG doesn't come into it.

 

[JB expat]

Do you think it is possible that the Max 8 will be sent to the grave yard as a permanently flawed design?

 

[Berlin]

Do you think it is possible that the Max 8 will be sent to the grave yard as a permanently flawed design?

Well, some of the US ones are already conveniently parked in the desert “graveyard”

 

[Berlin]

Lots more details on what was going on in the coughpit now @cnn. Pretty damning report for Boeing. Each to their own but a “software fix” will not be sufficient for me personally to confidently set foot on one of these planes.

https://edition-m.cnn.com/2019/04/0...rt-intl/index.html?r=https://edition.cnn.com/

 

[travelislife]

So what I don’t get is, a lot of the commentary here and elsewhere is that MCAS shouldn’t have even been in the picture at this altitude?

Just the whole philosophy of having a motorized system that can force the plane down against the pilots will is pretty unnerving.

 

[travelislife]

40 degrees nose down pitch seems insane!? Is that kind of pitch needed to even pull out of a stall?

 

[AviatorInsight]

Full preliminary report can be found here: http://www.ecaa.gov.et/documents/20...AVJ).pdf/4c65422d-5e4f-4689-9c58-d7af1ee17f3e

My bold...

• At 05:38:00 Take off roll commenced
• 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 05:38:46 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 05:39:22 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.
• 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 05:39:55, 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 05:40:12, 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.
• 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.
• 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 05:41:30, 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 05:42:54, 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

 

[Berlin]

Just the whole philosophy of having a motorized system that can force the plane down against the pilots will is pretty unnerving.

I find the whole philosophy of creating an airplane that needs a software fix to make it airworthy because someone wanted to make a quick buck by attaching engines that are too big to an old airframe HIGHLY unnerving to begin with!

 

[travelislife]

Full preliminary report can be found here: http://www.ecaa.gov.et/documents/20...AVJ).pdf/4c65422d-5e4f-4689-9c58-d7af1ee17f3e

My bold...

• At 05:38:00 Take off roll commenced
• 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 05:38:46 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 05:39:22 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.
• 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 05:39:55, 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 05:40:12, 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.
• 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.
• 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 05:41:30, 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 05:42:54, 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

Question for the pilots...is that as scary reading for you guys as it is for me as a layman?

 

[jb747]

Assuming MCAS had actually worked as Boeing had hoped (not designed, it’s not that good), in the entire history of the aircraft it might have saved a couple of aircraft from stalling....but just as likely not. Not necessarily crashing, just stalling. Now, this system has killed more people than it might have potentially saved.

Whilst I knew that the 737 still had the trim wheel, my understanding of it is that it is extremely slow. When Lion Air happened, I wondered if they’d gotten into the very nasty situation of having cut off the stab power, with the stab in such a nose down position that the control column could not bring the nose back up, and the trim wheel was too slow to remove the unwanted input. Looking at this rather horrifying transcript, it would seem that that was what this crew ended up with.

 

[AviatorInsight]

Question for the pilots...is that as scary reading for you guys as it is for me as a layman?

It certainly sends chills down my spine. 40° nose down and 500kts...

As a side note, if it’s any consolation to the general public, there’s a lot of noise being created by the pilot group within VA about this. We definitely want training in the simulator whether the software is fixed or not. The outcome is obviously going to take a little while...

 

[travelislife]

It's one thing designing and installing the system in the first place, and some errors in that have obviously been made. But the real negligence that I still can't believe is that Boeing put in this system and didn't tell the people in control of the machine that it even existed! That should be criminal charges.

 

[jb747]

40 degrees nose down pitch seems insane!? Is that kind of pitch needed to even pull out of a stall?

It is a totally insane attitude. It’s an attitude that has little use outside of high angle dive bombing. Airbus has an ‘unusual attitude law’, which kicks in if it sees silly attitudes in any axis. Basically it gives up, and stops all automated control, and gives the aircraft back to the pilots in direct law (i.e. the law with zero computer interpretation).

The amount of attitude change needed to recover from a stall varies, but it’s generally quite small, in the order of 5-10º. A very deep stall, like AF447, is something that most pilots stalling aircraft would not get anywhere near, and that would require a pretty extreme attitude. Most stalls, unless taken that step further into a spin, still have the aircraft within a small angle from the unstalled case. As soon as the attitude is changed enough to get the AoA below the stall, it immediately stops. But, you still need to recover from whatever attitude you’ve ended up in, and that can take substantial time and height.

 

[Quickstatus]

Pulling the yoke aft tilts the rear of the elevator up. As it is connected to the Stabiliser in front of it, there would be a moment tilting the Stabiliser up from the airflow forces on the elevator.

The pilots would have been trying to rotate the trim wheel which tilts the Stabiliser down. How much mechanical advantage is in the trim wheel?

So the trim wheel is slow, takes a lot of rotations to significantly change aircraft attitude, and when yoke is maximally pulled aft , and at high speed, there is likely not enough mechanical advantage to move the Stabiliser rapidly enough in an emergency - likely slower than usual.

 

[jb747]

It certainly sends chills down my spine. 40° nose down and 500kts...

I've seen similar, 45° and 6g took 2500' to recover.

 

[travelislife]

Okay, so next question...was this recoverable? What should have the pilots done (with the very limited time and altitude they had)? Or were they doomed as soon as the sensors started giving the wrong readings?

 

[AviatorInsight]

Whilst I knew that the 737 still had the trim wheel, my understanding of it is that it is extremely slow. When Lion Air happened, I wondered if they’d gotten into the very nasty situation of having cut off the stab power, with the stab in such a nose down position that the control column could not bring the nose back up, and the trim wheel was too slow to remove the unwanted input. Looking at this rather horrifying transcript, it would seem that that was what this crew ended up with.

This is the part I don’t like about the system. It moves differently to the current speed trim system in that when MCAS is activated it will trim a hell of a lot quicker than manual electric trim. The current speed trim system actually moves slower than the electric trim.

 

[oz_mark]

Okay, so next question...was this recoverable? What should have the pilots done (with the very limited time and altitude they had)? Or were they doomed as soon as the sensors started giving the wrong readings?

I'm sure Boeing have its test pilots in the simulators testing that question...