Boeing 737 MAX

[LN-RTP]

I was just answering your question on whether I think the airplane should be grounded.

I know, my above response was to another gentleman. This is getting too convoluted, my bad.

 

[Baker]

I know, my above response was to another gentleman. This is getting too convoluted, my bad.

I figured as much and no worries. And I agree with your thoughts on a new type versus stretching the 737. We all know the reason why that is....SWA!!! And to a lesser degree the other Carriers. UAL with almost 350 is no small customer either.

 

[LN-RTP]

I figured as much and no worries. And I agree with your thoughts on a new type versus stretching the 737. We all know the reason why that is....SWA!!! And to a lesser degree the other Carriers. UAL with almost 350 is no small customer either.

Yeah, SWA Rules the development (or lack of ) of the B-737. Ridiculous overhead Jurassic panel on the NG...?
I flew the -200 back in the day, actually rented one @ $39 a minute to do an FAA type ride at night, the sim was only 2-axis, had to fly the real jet for the Ride. Figured I get a job on the 737 with a fresh rating, instead I was hired on the 747..

 

[RT Firefly]

Greetings,
MAY be of some interest. I did not watch...

 

[twistedtree]

Greetings,
MAY be of some interest. I did not watch...

Wow, that's really good for an earth-bound knucklehead like me.


As a quick summary of his interpretation of events:


- Flight takes off and immediately gets whacko AOA from left sensor.


- They engage AP, but it kicks off a few seconds later. presumably because the AOA input is out of bounds.


- They retract flaps per normal takeoff, but as soon as the flaps a retracted, and with the AP off, MCAS kicks in because of the faulty AOA input.


- The crew counter acts MCAS, but after it's delay it kicks in again.


- They correctly disable the trim control.


- But because of the trimming up and down, the plane isn't climbing as normal, yet engines are still at 90%, so air speed is building up rapidly.


- Because of high air speed, they can't manually trim. The normal way to relieve tension on the trim mechanism is to let the plane nose down while you operate the trim wheels, but they don't have enough altitude to do that.


- But at this point they have control of the plan, but air speed is running out of control.


- It would appear they re-enable the electric trim, because there is an electric trim up, followed by an MCAS trim down. But by now they are going so fast that controls are exaggerated, and it's curtains.


With the benefit of hind sight.....


- Had they engaged the right side AP, all probably would have been fine running off the right AOA sensor, and with MCAS disabled.


- Had they just continued to counteract MCAS with the thumb switches, they probably would have been fine.


- Had they backed off on throttles to maintain acceptable air speed, they probably would have been OK.

 

[LN-RTP]

No doubt the MCAS system is a dud, but don’t let a dud kill you and your pax, fight back with all your might..Jeez.

Being an airline Captain is just not walking down the airport terminal with a fancy uniform, 4 gold stripes and trailing behind you F/Os, F/Es and a dozen Flight Attendants while looking like God.
You also have to perform if something goes wrong in the jet after take-off, or any time.
Like the Army slogan said: Be all you can be.

 

[LN-RTP]

. Because of high air speed, they can't manually trim.

Because the Captain and the Co-Pilot let the speed build up. Speed is dead or life in airplanes. If you don’t know how to control speed, you failed.

 

[Boat]

- Had they backed off on throttles to maintain acceptable air speed, they probably would have been OK.

They were way out of control. Normally they would be over three miles up at that speed. No way, never near that fast at low altitude.

 

[BruceK]

No doubt the MCAS system is a dud, but don’t let a dud kill you and your pax, fight back with all your might..Jeez.

Being an airline Captain is just not walking down the airport terminal with a fancy uniform, 4 gold stripes and trailing behind you F/Os, F/Es and a dozen Flight Attendants while looking like God.
You also have to perform if something goes wrong in the jet after take-off, or any time.
Like the Army slogan said: Be all you can be.

It`s clear enough, based on this and similar posts, the Max 787 is eminently safe and always was. The crashes are down to pilot incompetence and stupidity.
By now, every Max pilot, however stupid or illiterate,notwithstanding wearing gold braid a South American dictator would envy, must know of the easily avoided pilot errors which caused the crashes. Boeing, FAA, Air Safety Authorities around the world,even pesky French supporting Foreign Governments, should cease pussy footing and soft cocking around, needlessly inconveniencing an eager travelling public dying to get back on board a Max737.

Planes back in the air. Today. Job done. Peace and tranquility.

 

[LN-RTP]

It`s clear enough, based on this and similar posts, the Max 787 is eminently safe and always was. The crashes are down to pilot incompetence and stupidity.
By now, every Max pilot, however stupid or illiterate,notwithstanding wearing gold braid a South American dictator would envy, must know of the pilot errors which caused the crashes to avoid. Boeing, FAA, Air Safety Authorities around the world,even pesky French supporting Foreign Governments, should cease pussy footing and soft cocking around, needlessly inconveniencing an eager travelling public dying to get back on board a Max737.

Planes back in the air. Today. Job done. Peace and tranquility.

Wow, try not to post after drinking, or smoking crack.

 

[BruceK]

Wow, try not to post after drinking, or smoking crack.

There`s a wild assertion you are yet to level against the pilots.
You guys need to come to your senses. If my post, powered by neither drink nor drug but by a sense of injustice at your sarcastic blaming the pilots, brings some reality to your biased approach, it will achieve something.

 

[twistedtree]

It`s clear enough, based on this and similar posts, the Max 787 is eminently safe and always was. The crashes are down to pilot incompetence and stupidity.
By now, every Max pilot, however stupid or illiterate,notwithstanding wearing gold braid a South American dictator would envy, must know of the easily avoided pilot errors which caused the crashes. Boeing, FAA, Air Safety Authorities around the world,even pesky French supporting Foreign Governments, should cease pussy footing and soft cocking around, needlessly inconveniencing an eager travelling public dying to get back on board a Max737.

Planes back in the air. Today. Job done. Peace and tranquility.

I'm not sure if my hindsight reflections prompted this. Here's what I said:


- Had they engaged the right side AP, all probably would have been fine running off the right AOA sensor, and with MCAS disabled.

- Had they just continued to counteract MCAS with the thumb switches, they probably would have been fine.

- Had they backed off on throttles to maintain acceptable air speed, they probably would have been OK.



That all seems to be true, and is reflective of what the pilots could have done differently. I don't mean to blame them, just learn from the situation.


I also think there is plenty that could have been done better with the plane itself, and the process that brought the plane into service. In no particular order...



- It seem clear that pilots should have been trained on MCAS, when it is enabled, what it does, and why. Also how to identify errant operation, and what corrective action to take



- It seems that a system like MCAS that can provide autonomous flight control inputs, should always be redundant, not just as an option.


- MCAS should probably have it's own disable switch, or there should be a very clear procedure on how to disable and/or work around it. For example, provide thumb counter trim when flaps are up and AP is disengaged, i.e. when MCAS is enabled. Then get the AP engaged as quickly as you can.



- Why was the MCAS trim increment changed from .6 to 2.5? There must have been a reason.


- The trim increment change in MCAS probably should have been more deeply scrutinized by the FAA. In fact, the full behavior of MCAS should have been more carefully scrutinized.


My point is that it seems there are lots of contributing causes. Just because eliminating one of them would have prevented the crash, doesn't make that cause any more significant that the dozen or so other causes that would similarly saved the flight if eliminated.


For whatever reason, people seem to want a single cause, or single person to blame. "It was the pilots and their crappy third world airlines". "It was the Boeing-FAA regulatory revolving door". "It was corporate greed to avoid re-classing a new design". "It's planes flown by computers and sissies instead of real men who can Chuck Yaeger their way out of any situation". But these are really just reflections of our own belief systems, and our need to see everything in a way that supports it.

 

[Baker]

- MCAS should probably have it's own disable switch, or there should be a very clear procedure on how to disable and/or work around it. For example, provide thumb counter trim when flaps are up and AP is disengaged, i.e. when MCAS is enabled. Then get the AP engaged as quickly as you can.



-

It does and there is. The trim cutout switches kill MCAS. They are very easy to get to and very easy to activate.

Scrambling to get the autopilot on as an "emergency procedure"(that is the way I read it) is not a good one. One should be flying the plane and not trying to delegate control to the machinery. As we have discussed at length but I will put it another way, we are trained to shed automation as control of the aircraft comes into question. And also, in Boeing aircraft, the autopilot is very picky about trim when it is engaged. IOW, if the airplane is out of trim when you attempt to engage the AP, it will not engaged. If you have pressure on the controls, it will not engage. So you learn real quickly that when you go for that button, you trim the pressure off of the controls...you let go of the controls, and then hit the button. All a very subconscious act but it is not at all natural for a newbie. I always see them wondering why the AP won't engage while they are hanging onto the yoke.

 

[Ski in NC]

If you put stab trim switches in "cutout", does that also kill the yoke trim buttons? So the only way to adjust stab trim is now the wheels?

 

[Baker]

If you put stab trim switches in "cutout", does that also kill the yoke trim buttons? So the only way to adjust stab trim is now the wheels?

100% correct

 

[Ski in NC]

And I guess that is where the aerodynamic loads on the stabilizer (with elevator held for nose up and at very high speed) might make it hard to use the trim wheel?

 

[Baker]

And I guess that is where the aerodynamic loads on the stabilizer (with elevator held for nose up and at very high speed) might make it hard to use the trim wheel?

Yep...it is a mechanical linkage.

 

[twistedtree]

It does and there is. The trim cutout switches kill MCAS. They are very easy to get to and very easy to activate.

I'll apologize in advance for my novice understanding of all this... and really appreciate getting it corrected here...


But do I understand correctly that the trim cutout switches also turn off electric trim as controlled by the thumb switches? So trim cutout leaves you only with manually turning the trim wheel, which I gather from the video is hard to impossible to do when there is a lot of pressure on their control surfaces?


I was thinking that an MCAS cutout would be a way to shed automation, but not also give up power-assisted control of the trim.

 

[LN-RTP]

I was thinking that an MCAS cutout would be a way to shed automation, but not also give up power-assisted control of the trim.

To deactivate MCAS and keep electric trim, lower the flaps.

 

[twistedtree]

To deactivate MCAS and keep electric trim, lower the flaps.

Are there air speed restrictions on doing that?

And of course it presumes the pilots understand the operation of MCAS and know that will disable it.

 

[LN-RTP]

Are there air speed restrictions on doing that?

And of course it presumes the pilots understand the operation of MCAS and know that will disable it.

Yes, speed restrictions on the flaps.

This bulletin was issued in November 2018 to all MAX Operators, including Ethiopian Airlines and was incorporated in their FCOM:

“In the event of erroneous AOA data, the pitch trim system can trim the stabiliser nose down in increments lasting up to 10 seconds. The nose down stabiliser trim movement can be stopped and reversed with the use of the electric stabiliser trim switches but may restart 5 seconds after the electric stabiliser trim switches are released. Repetitive cycles of uncommanded nose down stabiliser continue to occur unless the stabiliser trim system is deactivated through use of both STAB TRIM CUTOUT switches in accordance with the existing procedures in the Runaway Stabiliser NNC. It is possible for the stabiliser to reach the nose down limit unless the system inputs are counteracted completely by pilot trim inputs and both STAB TRIM CUTOUT switches are moved to CUTOUT.”

Source:

https://www.skybrary.aero/index.php...il&utm_term=0_e405169b04-b612ce0882-276530305

 

[Genecop]

https://youtu.be/HBqDcUqJ5_Q

 

[Ski in NC]

So if MCAS commands nose down, you counteract it by using the yoke trim switch and get stab back to a good position. THEN hit the cutout switch. Sounds like the trim switch will over ride the MCAS trim signal.

Is it that simple?

I watched the vid posted in #292, very informative.

 

[LN-RTP]

. Is it that simple?

Should be, unless there was something wrong with the Captain’s trim switch as he told the F/O to “help me trim” or “trim with me”.

 

[Moonstruck]

Don't know if this could be of some help. It is purported to be from the preliminary report.


From: xxx
Subject: FW: Pre-lim Ethiopian Airlines Boeing 737 MAX 8 accident report
Date: April 8, 2019 at 8:15:38 AM EDT
To: xxx

Status:
Preliminary - official
Date:
Sunday 10 March 2019
Time:
08:44
Type:
Silhouette image of generic B38M model; specific model in this crash may look slightly different
Boeing 737 MAX 8
Operator:
Ethiopian Airlines
Registration:
ET-AVJ
C/n / msn:
62450/7243
First flight:
2018-10-30 (4 months)
Total airframe hrs:
1330
Cycles:
382
Engines:
2 CFMI LEAP-1B
Crew:
Fatalities: 8 / Occupants: 8
Passengers:
Fatalities: 149 / Occupants: 149
Total:
Fatalities: 157 / Occupants: 157
Aircraft damage:
Destroyed
Aircraft fate:
Written off (damaged beyond repair)
Location:
50 km (31.3 mls) ESE of Addis Ababa-Bole Airport (ADD) ( Ethiopia)
Phase:
En route (ENR)
Nature:
International Scheduled Passenger
Departure airport:
Addis Ababa-Bole Airport (ADD/HAAB), Ethiopia
Destination airport:
Nairobi-Jomo Kenyatta International Airport (NBO/HKJK), Kenya
Flightnumber:
ET302
Narrative:
Ethiopian Airlines flight ET302, a Boeing 737 MAX 8, crashed shortly after takeoff from Addis Ababa-Bole Airport, Ethiopia. There were no survivors among the 157 occupants.
Takeoff roll began from runway 07R at a field elevation of 2333 m at 08:38 hours local time, 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.

At 08:38:44, 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 the left AOA value reached 74.5° in less than a second while the right AOA reached a maximum value of 15.3°. At this time, the left stick shaker activated and remained activeuntil near the end of the flight. 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 flight.
The captain attempted to engage the autopilot twice, but this resulted in two autopilot warnings.
At 08:39:06, the Captain advised the First-Officer to contact the radar controller and First Officer reported a 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 08:39:22 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 08:39:29, the radar controller identified ET302 and instructed them to climb FL340 and when able a right turn direct to RUDOL. The First-Officer acknowledged this.

At 08:39:42, 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 08:39:45, Captain requested flaps up and First-Officer acknowledged. One second later, the flap handle moved from 5 to 0 degrees and flaps retraction began.
At 08:39:50, 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.
The autopilot then disengaged and at 08:39:57, the Captain advised again the First-Officer to request to maintain runway heading and that they are having flight control problems.
At 08:40:00 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 08:40:05, the First-Officer reported to ATC that they were unable to maintain SHALA 1A and requested runway heading which was approved by ATC.

The column moved aft and a positive climb was re-established during the automatic AND motion.
At 08:40:12, 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 08:40:20, 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 08:40:27, the Captain advised the First-Officer to trim up with him.
At 08:40:28 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 08:40:35, the First-Officer called out "stab trim cut-out" two times. Captain agreed and First-Officer confirmed stab trim cut-out.
At 08:40:41, 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 08:40:44, the Captain called out three times "Pull-up" and the First-Officer acknowledged.
At 08:40:50, 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 08:40:56, the First-Officer requested ATC to maintain 14,000 ft and reported that they are having flight control problem. ATC approved.
From 08:40:42 to 08:43:11 (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 08:41:20, the right overspeed clacker was recorded on CVR. It remained active until the end of the recording.
At 08:41:21, the selected altitude was changed from 32000 ft to 14000 ft.
At 08:41:30, the Captain requested the First-Officer to pitch up with him and the First-Officer acknowledged.
At 08:41:32, the left overspeed warning activated and was active intermittently until the end of the recording.
At 08:41:46, 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 08:41:54, the First-Officer replied that it is not working.
At 08:42:10, the Captain asked and the First-Officer requested radar control a vector to return and ATC approved.
At 08:42:30, ATC instructed ET302 to turn right heading 260 degrees and the First-Officer acknowledged.
At 08:42:43, the selected heading was changed to 262 degrees.
At 08:42:51, the First-Officer mentioned Master Caution Anti-Ice. The Master Caution is recorded on DFDR.
At 08:42:54, both pilots called out "left alpha vane".
At 08:43:04, the Captain asked the First Officer to pitch up together and said that pitch is not enough.
At 08:43:11, about 32 seconds before the end of the recording, at approximately 13,400 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 08:43:20, 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.



Accident investigation:
cover
Investigating agency:
AAIB Ethiopia
Status:
Investigation ongoing
Duration:
25 days ()
Accident number:
AI-01/19
Download report:
Preliminary report


Classification:
Loss of control


Sources:
» Preliminary report




METAR Weather report:
05:00 UTC / 08:00 local time:
HAAB 100500Z 06008KT 9999 FEW025 16/10 Q1029

06:00 UTC / 09:00 local time:
HAAB 100600Z 07010KT 9999 FEW025 18/09 Q1029

 

[Baker]

To deactivate MCAS and keep electric trim, lower the flaps.

Why not turn on the autopilot?

That is a rhetirical question. Maybe my reading compreshension sucks but nowhere does it say to lower the flaps in that bulletin. And nowhere does it say to lower the flaps anywhere in our procedures. And nowhere did it say that flaps would disable MCAS before these accidents....so you are operating on hindsight once again.

 

[LN-RTP]

Why not turn on the autopilot?

Yeah, that would also do it, but these guys had an FCC going apes... because of bad input and the left autopilot clicked off, not sure they tried the right one.
The runaway stab checklist says to turn the autopilot off anyways?

 

[Baker]

Yeah, that would also do it, but these guys had an FCC going apes... because of bad input and the left autopilot clicked off, not sure they tried the right one.
The runaway stab checklist says to turn the autopilot off anyways?

My edit might have been after your reply....but lowering the flaps really is no better than turning on the AP...which was my point.

 

[LN-RTP]

Why not turn on the autopilot?

That is a rhetirical question. Maybe my reading compreshension sucks but nowhere does it say to lower the flaps in that bulletin. And nowhere does it say to lower the flaps anywhere in our procedures. And nowhere did it say that flaps would disable MCAS before these accidents....so you are operating on hindsight once again.

Here we go again: This whole thread is in hindsight.
Nowhere did I reference a procedure or bulletin advising to lower flaps, you are reading into stuff that is not there: Again: It is not procedure, nor did I say it was, jeez..

Somebody was asking how to deactivate or turn of the MCAS system:
The answer is flaps or autopilot. (It has already been mentioned before several times, but maybe some folks did not read the whole thread. Flaps or Autopilot, it is a fact, NOT a procedure, jeez again )

 

[Baker]

Somebody was asking how to deactivate or turn of the MCAS system:
The answer is flaps or autopilot.

NO...IT...IS...NOT!!!!!!

The answer is TRIM CUTOUT SWITCHES!!!!.

Hindsight does absolutely nothing for us. We learn nothing from it.