Ethiopian airliner down in Africa
I understand what you are saying GG and I agree that engaging A/P is not the way to go about solving problems like this, I also agree that an attitude and thrust setting is where you want to end up in this situation, however, between sensing the stick shaker, recognising it’s meaning, reassessing the airspeed, maybe glancing at the flap indicator, sensing that there are other warnings occurring and deciding not to lower the nose as per the memory items because it may be a false stick shaker, time will pass, how much time? As I said, I think some posters are underestimating how much time would pass before they reduced thrust that close to the ground.
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https://ecfr.io/Title-14/se14.3.121_1344
"§121.344 Digital flight data recorders for transport category airplanes.
(a) . . . The operational parameters required to be recorded by digital flight data recorders required by this section are as follows: . . .
. . . (19) Pitch trim surface position or parameters of paragraph (a)(82) of this section if currently recorded;
. . . (82) Cockpit trim control input position—pitch . . . "
So toss a coin. With help from Boeing and the carrier(s), the investigators should be able to determine the signal source.
"§121.344 Digital flight data recorders for transport category airplanes.
(a) . . . The operational parameters required to be recorded by digital flight data recorders required by this section are as follows: . . .
. . . (19) Pitch trim surface position or parameters of paragraph (a)(82) of this section if currently recorded;
. . . (82) Cockpit trim control input position—pitch . . . "
So toss a coin. With help from Boeing and the carrier(s), the investigators should be able to determine the signal source.
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73,
I’ll predict that one of major findings in both of these accidents is that everybody forgot just to fly the aircraft.
The B737 is a very simple aircraft with lots of bells and whistles, most of which are nice to have, not must have.
An enthusiastic Boeing instructor once took me to 35,000 ft in the simulator at the end of a training session then reached up to the overhead panel and turned everything off.
The aircraft still flew.
Dont think they do much of that stuff anymore.
I’ll predict that one of major findings in both of these accidents is that everybody forgot just to fly the aircraft.
The B737 is a very simple aircraft with lots of bells and whistles, most of which are nice to have, not must have.
An enthusiastic Boeing instructor once took me to 35,000 ft in the simulator at the end of a training session then reached up to the overhead panel and turned everything off.
The aircraft still flew.
Dont think they do much of that stuff anymore.
Originally Posted by Albino
It's an interesting point whether the stab readout is taken from what is commanded or the position of the jack. Considering the AND command is registered without stab movement I suspect it is demand, it's how the narrative reads as well.
Originally Posted by Geroge Glass
I’ll predict that one of major findings in both of these accidents is that everybody forgot just to fly the aircraft.
73,
I’ll predict that one of major findings in both of these accidents is that everybody forgot just to fly the aircraft.
The B737 is a very simple aircraft with lots of bells and whistles, most of which are nice to have, not must have.
An enthusiastic Boeing instructor once took me to 35,000 ft in the simulator at the end of a training session then reached up to the overhead panel and turned everything off.
The aircraft still flew.
Dont think they do much of that stuff anymore.
I’ll predict that one of major findings in both of these accidents is that everybody forgot just to fly the aircraft.
The B737 is a very simple aircraft with lots of bells and whistles, most of which are nice to have, not must have.
An enthusiastic Boeing instructor once took me to 35,000 ft in the simulator at the end of a training session then reached up to the overhead panel and turned everything off.
The aircraft still flew.
Dont think they do much of that stuff anymore.
MCAS!
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MCAS is not needed or wanted
This constant assumption by aircraft manufacturers that the pilots don't know f*** all about flying and insist on installing complicated systems to act as a safety pilot is crazy, how often do pilots stall airliners?? very very rarely is the answer, and if they were stupid enough to stall the aircraft, recovery is relatively simple, assuming some altitude is available. A message to Boeing and Airbus, please let the pilots fly the aicraft you build and stop confusing them with unnecessary and untimately dangerous technology.
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so will the software fix, and slightly updated training, be enough to get the MAX back into revenue service?
I predict after ET not. It's apparent even with MCAS turned off, the cockpit does not return to peace and tranquility where average ability pilots can regain control and land. It's apparent from the ET interim report that a lot more was going on in the cockpit, and that was it was beyond the two pilots to get it back together, mainly due to excess speed and aerodynamic forces making proper trim next to impossible without some, as yet, untrained yoyo, manoeuvre.
I would suggest no regulator would be willing to pass the MAX back into service based on a patch and minor training update.
G
I predict after ET not. It's apparent even with MCAS turned off, the cockpit does not return to peace and tranquility where average ability pilots can regain control and land. It's apparent from the ET interim report that a lot more was going on in the cockpit, and that was it was beyond the two pilots to get it back together, mainly due to excess speed and aerodynamic forces making proper trim next to impossible without some, as yet, untrained yoyo, manoeuvre.
I would suggest no regulator would be willing to pass the MAX back into service based on a patch and minor training update.
G
Originally Posted by Albino
the aircraft was not controlled with pitch AND trim as per the Unscheduled Stab Trim memory items. Nobody has questioned the validity of this statement.
Then you pull out the two page AD memo from Boeing and recall what it said: at the bottom of page two "Electric stabiliser trim can be used to neutralise...".
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73,
I’ll predict that one of major findings in both of these accidents is that everybody forgot just to fly the aircraft.
The B737 is a very simple aircraft with lots of bells and whistles, most of which are nice to have, not must have.
An enthusiastic Boeing instructor once took me to 35,000 ft in the simulator at the end of a training session then reached up to the overhead panel and turned everything off.
The aircraft still flew.
Dont think they do much of that stuff anymore.
I’ll predict that one of major findings in both of these accidents is that everybody forgot just to fly the aircraft.
The B737 is a very simple aircraft with lots of bells and whistles, most of which are nice to have, not must have.
An enthusiastic Boeing instructor once took me to 35,000 ft in the simulator at the end of a training session then reached up to the overhead panel and turned everything off.
The aircraft still flew.
Dont think they do much of that stuff anymore.
73qanda, ATCWhatcher,
putting the event in context and human factors
also with, onsoutherntip re interpretation of FDR trim command and tail trim movement - they may differ; see post Ethiopian Prelim Report and the back links.
Adding to some of the ‘historic’ concerns, would the slightly smaller trim wheel in latter versions of the 737 reduce the effective torque which could be applied in grabbing the wheel as part of the runaway trim drill - and applying manual trim to recover ?
putting the event in context and human factors also with, onsoutherntip re interpretation of FDR trim command and tail trim movement - they may differ; see post Ethiopian Prelim Report and the back links.
Adding to some of the ‘historic’ concerns, would the slightly smaller trim wheel in latter versions of the 737 reduce the effective torque which could be applied in grabbing the wheel as part of the runaway trim drill - and applying manual trim to recover ?
For the benefit of the “MCAS is just there to satisfy a paper regulation” mob; the aircraft control characteristics regulations require that the stick force increase with increasing attitude. This is not a “paper regulation” but a real world need for the change in attitude to be proportional to force in other words the required control inputs as applied by the pilots don’t reduce or worse reverse with changes in attitude.
To put that in automotive terms some of you might understand; oversteer is not allowed.
To put that in automotive terms some of you might understand; oversteer is not allowed.
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I have grown slightly cross eyed following the huge volume of posts concerning the tragic events with the 737 MAX. One item that seems to have been mentioned just once (or thereabouts) is that things only started to go pear shaped immediately following flap retraction. Surely the clue should have been obvious to any adequate pilot and the previous configuration restored. As far as I understand things that would have saved the day. I have done a fair amount of 737 work but that was back in the day when they worked like normal aeroplanes (737 200& 400) so I may be wrong. This principle, however, has saved my life twice and I don't pretend to be anything other than an average operator. Am I wrong?
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Nothing in the Memory items like that (as per the report, page 30). If the runaway continues after AP is switched off, is says to switch off the trim. Nothing about "counter trim with control column switches, return aircraft to pitch neutral then switch off trim" as you are alluding to. And even if they had "disengaged the autothrottle", what would that have achieved? Nothing unless you then pull off a fistful of thrust...
Then you pull out the two page AD memo from Boeing and recall what it said: at the bottom of page two "Electric stabiliser trim can be used to neutralise...".
Then you pull out the two page AD memo from Boeing and recall what it said: at the bottom of page two "Electric stabiliser trim can be used to neutralise...".
What would disconnecting the autothrottle have achieved? Well you could set thrust to something more sensible and fly the aircraft.
You mean page 2 of the memo that gave specific operating instructions to crew? It even included a note (obvious to most with any common sense!) to put the aircraft in trim, then cut out the stabs.
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The Indonesian preliminary report, para. 1.18.1, starting on pg. 19 (pg. 28 of PDF), has a narrative of the flight prior to the Lion Air accident.
The FDR data for that flight is plotted as Fig. 7 on pg. 16 (pg. 25 of PDF). The time scale is a bit odd (about 11 minutes 10 seconds per major division), and there are no numbers on most of the vertical axes.
The plot is also for the whole flight, although dealing with MCAS occurs over about 10 minutes very early in the climb. Hence the scale makes it hard to see the details of that portion.
portion of FIg. 7 from Indonesian report
Here are vertical velocity and altitude plots of ADS-B data for that flight made using data posted on-line by FlightRadar24.
There are quite a few cycles of MCAS activation before the pilot cut out the stab trim, with one really steep descent. The bottom of that descent is about where the FO made the first PAN PAN call, per the narrative.
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I have grown slightly cross eyed following the huge volume of posts concerning the tragic events with the 737 MAX. One item that seems to have been mentioned just once (or thereabouts) is that things only started to go pear shaped immediately following flap retraction. Surely the clue should have been obvious to any adequate pilot and the previous configuration restored. As far as I understand things that would have saved the day. I have done a fair amount of 737 work but that was back in the day when they worked like normal aeroplanes (737 200& 400) so I may be wrong. This principle, however, has saved my life twice and I don't pretend to be anything other than an average operator. Am I wrong?
From one of the media reports:
So, this MAX pilot’s first response to a stall warning (which could be genuine) is to deactivate the trim. This is a terrible indictment of the awful kludge which the airframe and control systems are on the MAX, that something like an incipient low-level stall comes second in priority to MCAS. The even sillier thing is that if it was a genuine stick shake, you’ve now disabled the system that was going to help you recover... 
...“If I had been flying a MAX with stickshaker activation at liftoff after the Lion Air accident, shutting off the trim would have been accomplished in a matter of seconds, not minutes,” says one U.S.-based MAX pilot. “I probably would have activated the stabilizer trim cutout switches before the gear was even up. Why that didn’t happen on the Ethiopian flight is a mystery to me.”
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I feel for the crew in these circumstances as they appear to have been overloaded to the extreme. Everyone is looking back with hindsight but a couple of things that I have seen in the Preliminary report:
1. It looks like a bird has hit and sheared off the AoA vane. It settles at 75 degrees Up and the aircraft is 15 nose up so the counterweight is holding it down. Then repeatedly trying to put in the Autopilot with Stick shaker going was only going to make a bad situation go even worse. Not a recommended procedure I have found anywhere in the Boeing Manuals for any aircraft. Very similar to a Ryanair event a few years ago in an 800. Crew manually flew it around and landed it.
2. I can't see where any complete checklists were done. None at all. Just the Stab Trim cut-outs thrown to cut-off by the FO when the Captain was trimming the aircraft back to neutral. If the FO had waited for the call for the checklist and actioned it with the Captain they may have been in a better position closer to neutral. Remember that MCAS in the old software form stops when you start to trim it back with the electric trim. When you stop you have 5 seconds so then is a good time to do the checklist and throw the switches. From what I can see there were two full applications of MCAS prior to them putting the Stab motors back on.
3. It appears that while in manual mode the Stab was trimmed even further nose down. I think this may have been inadvertent by the FO but made a bad situation even worse. It also made it more difficult to then manually trim back and they gave up. As someone has already mentioned you need to put a lot of force (around 50 lbs from memory) and have some coordination to wind it back at high speed. Or you pull the power back and slow down which brings us to
4. The Take off power was not at any stage pulled back and they went through VMO within about 2 minutes. From there they kept accelerating. All the way to 500 kts
5. Then to put the system back to normal then meant that MCAS was still inputting to the circuit. That was it. No chance of recovery
One of the things that Manufacturers need to realise is that a lot of their customers do not have English as their first language. (Frankly some of the Airbus manuals I have had to read with Franglish take this to another level as well). If the guys had read all the info on MCAS and understood it would things have been different? With stick shaker going on during departure in the Heavier machines you never select flaps up until you confirm what has happened and you are well clear of terrain. To take the Flaps up at 1000 ft in this situation knowing that the shaker was going was an interesting move most likely reflex to the quickly accelerating aircraft.
As someone else has said that is why Airline Crew get paid well and why training should be more about the things that will cause you large harm and how you react rather than some of the tick the box exercises.
Does the aircraft need to be redesigned. Nope. The software does need to be changed and Boeing need to be a lot more rigorous in how they approach these critical systems. I have flown the MAX and it is a nice aircraft to fly. Lets see where the media take the world with this one.
1. It looks like a bird has hit and sheared off the AoA vane. It settles at 75 degrees Up and the aircraft is 15 nose up so the counterweight is holding it down. Then repeatedly trying to put in the Autopilot with Stick shaker going was only going to make a bad situation go even worse. Not a recommended procedure I have found anywhere in the Boeing Manuals for any aircraft. Very similar to a Ryanair event a few years ago in an 800. Crew manually flew it around and landed it.
2. I can't see where any complete checklists were done. None at all. Just the Stab Trim cut-outs thrown to cut-off by the FO when the Captain was trimming the aircraft back to neutral. If the FO had waited for the call for the checklist and actioned it with the Captain they may have been in a better position closer to neutral. Remember that MCAS in the old software form stops when you start to trim it back with the electric trim. When you stop you have 5 seconds so then is a good time to do the checklist and throw the switches. From what I can see there were two full applications of MCAS prior to them putting the Stab motors back on.
3. It appears that while in manual mode the Stab was trimmed even further nose down. I think this may have been inadvertent by the FO but made a bad situation even worse. It also made it more difficult to then manually trim back and they gave up. As someone has already mentioned you need to put a lot of force (around 50 lbs from memory) and have some coordination to wind it back at high speed. Or you pull the power back and slow down which brings us to
4. The Take off power was not at any stage pulled back and they went through VMO within about 2 minutes. From there they kept accelerating. All the way to 500 kts
5. Then to put the system back to normal then meant that MCAS was still inputting to the circuit. That was it. No chance of recovery
One of the things that Manufacturers need to realise is that a lot of their customers do not have English as their first language. (Frankly some of the Airbus manuals I have had to read with Franglish take this to another level as well). If the guys had read all the info on MCAS and understood it would things have been different? With stick shaker going on during departure in the Heavier machines you never select flaps up until you confirm what has happened and you are well clear of terrain. To take the Flaps up at 1000 ft in this situation knowing that the shaker was going was an interesting move most likely reflex to the quickly accelerating aircraft.
As someone else has said that is why Airline Crew get paid well and why training should be more about the things that will cause you large harm and how you react rather than some of the tick the box exercises.
Does the aircraft need to be redesigned. Nope. The software does need to be changed and Boeing need to be a lot more rigorous in how they approach these critical systems. I have flown the MAX and it is a nice aircraft to fly. Lets see where the media take the world with this one.
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From one of the media reports:
So, this MAX pilot’s first response to a stall warning (which could be genuine) is to deactivate the trim. This is a terrible indictment of the awful kludge which the airframe and control systems are on the MAX, that something like an incipient low-level stall comes second in priority to MCAS. The even sillier thing is that if it was a genuine stick shake, you’ve now disabled the system that was going to help you recover...
So, this MAX pilot’s first response to a stall warning (which could be genuine) is to deactivate the trim. This is a terrible indictment of the awful kludge which the airframe and control systems are on the MAX, that something like an incipient low-level stall comes second in priority to MCAS. The even sillier thing is that if it was a genuine stick shake, you’ve now disabled the system that was going to help you recover...
But still the Most important question is:
Why did they not use electric Stab trim to get back into an in trim condition without any control column pitch forces and then Hit the cutout switches???
so will the software fix, and slightly updated training, be enough to get the MAX back into revenue service?
I predict after ET not. It's apparent even with MCAS turned off, the cockpit does not return to peace and tranquility where average ability pilots can regain control and land. It's apparent from the ET interim report that a lot more was going on in the cockpit, and that was it was beyond the two pilots to get it back together, mainly due to excess speed and aerodynamic forces making proper trim next to impossible without some, as yet, untrained yoyo, manoeuvre.
I would suggest no regulator would be willing to pass the MAX back into service based on a patch and minor training update.
G
I predict after ET not. It's apparent even with MCAS turned off, the cockpit does not return to peace and tranquility where average ability pilots can regain control and land. It's apparent from the ET interim report that a lot more was going on in the cockpit, and that was it was beyond the two pilots to get it back together, mainly due to excess speed and aerodynamic forces making proper trim next to impossible without some, as yet, untrained yoyo, manoeuvre.
I would suggest no regulator would be willing to pass the MAX back into service based on a patch and minor training update.
G
The 737 safety philosophy means that it turns into a conventional stick and rudder aircraft once you turn the AP off. And that with redundant left and right seat set of controls. The PF assumes in AP off mode that he has full authority on the flight controls and surfaces. There are automatic flap retract in over speed left but that does not reduce his controll over the aircraft.
If you brake that philosophy by introducing “features” overriding PF control inputs they need to be full FBW worth with all fail safe features needed for a FBW control.
I do not see how Boeing can implement that easily into the 737 MAX.
With the two accidents it came out, that the manual trim wheel can not be actuated manually in a high elevator deflection and high speed situation. That aerobatic manovering is the cure for that can unlikely be certified for a transport category aircraft.
With 50 years of 737 operation that was not a big problem because nobody was as stupid as the MCAS system and gave full 5 seconds of AND trim in an already peculiar nose down situation close to the ground.
In a fighter jet in such a case you might invert the aircraft and rollercoaster the stuck trim out. But that is not a solution for a transport category aircraft.