Moderators: richierich, ua900, PanAm_DC10, hOMSaR
By Bjorn Fehrm
November 14, 2018, © Leeham News.: The automatic trim Boeing introduced on the 737 MAX, called MCAS, was news to us last week. Graver, it was news to the Pilots flying the MAX since 18 months as well.
Boeing and its oversight, the FAA, decided the Airlines and their Pilots had no need to know. The Lion Air accident can prove otherwise.
Sooner787 wrote:I know there are some MAX customers that have yet to take delivery of their new jets ,
Alaska for instance..... Might AS decide to cancel their MAX orders , especially since they
now have A321NEOS on property. I would also guess Lion Air might be reconsidering
their Max order book as well.
Sooner787 wrote:I know there are some MAX customers that have yet to take delivery of their new jets ,
Alaska for instance..... Might AS decide to cancel their MAX orders , especially since they
now have A321NEOS on property. I would also guess Lion Air might be reconsidering
their Max order book as well.
Finn350 wrote:Sooner787 wrote:I know there are some MAX customers that have yet to take delivery of their new jets ,
Alaska for instance..... Might AS decide to cancel their MAX orders , especially since they
now have A321NEOS on property. I would also guess Lion Air might be reconsidering
their Max order book as well.
Not likely that there are any contractual clauses to justify deferrals or cancellations on 737 MAX orders based on thuis defect.
Finn350 wrote:Sooner787 wrote:I know there are some MAX customers that have yet to take delivery of their new jets ,
Alaska for instance..... Might AS decide to cancel their MAX orders , especially since they
now have A321NEOS on property. I would also guess Lion Air might be reconsidering
their Max order book as well.
Not likely that there are any contractual clauses to justify deferrals or cancellations on 737 MAX orders based on this defect.
BoeingGuy wrote:Finn350 wrote:Sooner787 wrote:I know there are some MAX customers that have yet to take delivery of their new jets ,
Alaska for instance..... Might AS decide to cancel their MAX orders , especially since they
now have A321NEOS on property. I would also guess Lion Air might be reconsidering
their Max order book as well.
Not likely that there are any contractual clauses to justify deferrals or cancellations on 737 MAX orders based on thuis defect.
Let’s be very clear. The defect was the AOA probe, not the airplane design.
LDRA wrote:Can be indirect. For example, one of the cert bodies does something to 737Max type certificate
ScottB wrote:LDRA wrote:Can be indirect. For example, one of the cert bodies does something to 737Max type certificate
Drama much? IMO, worst case is that Boeing is forced to issue a software update which disables the new safety feature completely or when there's a malfunction of one of the AOA sensors (or a disagreement is detected). Or the resolution may be what the emergency AD was intended to accomplish -- informing all pilots of how to respond to a potentially unsafe condition caused by an AOA sensor malfunction.
Otherwise we would have seen the A330 TC suspended as a result of AF 447 given that the BEA pointed to the Human Computer Interface of the A330 being a potential contributing factor to the loss of that aircraft.
ScottB wrote:LDRA wrote:Can be indirect. For example, one of the cert bodies does something to 737Max type certificate
Drama much? IMO, worst case is that Boeing is forced to issue a software update which disables the new safety feature completely or when there's a malfunction of one of the AOA sensors (or a disagreement is detected). Or the resolution may be what the emergency AD was intended to accomplish -- informing all pilots of how to respond to a potentially unsafe condition caused by an AOA sensor malfunction.
Otherwise we would have seen the A330 TC suspended as a result of AF 447 given that the BEA pointed to the Human Computer Interface of the A330 being a potential contributing factor to the loss of that aircraft.
Dantepel wrote:Sometimes posters on the site remind me of my kids. They post what they hope will happen as what the think will happen.
BoeingGuy wrote:Finn350 wrote:Sooner787 wrote:I know there are some MAX customers that have yet to take delivery of their new jets ,
Alaska for instance..... Might AS decide to cancel their MAX orders , especially since they
now have A321NEOS on property. I would also guess Lion Air might be reconsidering
their Max order book as well.
Not likely that there are any contractual clauses to justify deferrals or cancellations on 737 MAX orders based on thuis defect.
Let’s be very clear. The defect was the AOA probe, not the airplane design.
BoeingGuy wrote:Finn350 wrote:Sooner787 wrote:I know there are some MAX customers that have yet to take delivery of their new jets ,
Alaska for instance..... Might AS decide to cancel their MAX orders , especially since they
now have A321NEOS on property. I would also guess Lion Air might be reconsidering
their Max order book as well.
Not likely that there are any contractual clauses to justify deferrals or cancellations on 737 MAX orders based on thuis defect.
Let’s be very clear. The defect was the AOA probe, not the airplane design.
seahawk wrote:It is all speculation until we have all facts. It would be strange if only the failure of MCAS caused the crash, as pilots should be able to handle it, but we must consider the possibility of multiple sensor or system failures and then things might get complicated.
PSAatSAN4Ever wrote:Once again, I will point out that we have been through this before: December 27, 1991, SK 751. Despite following all procedures correctly, the flight crew discovered that every time they reduced engine power, something was reversing their actions and turned the thrust up. Every time they reduced, the thrust returned higher, until it burned up the engines and left the plane a glider. Fortunately in that incident, everyone survived. The cause of the engine surges? A piece of software McDonnell Douglas installed to prevent stalling that they didn't tell SAS about. The pilot of that flight never flew again, not being able to trust an airplane ever again.
BoeingGuy wrote:Finn350 wrote:Sooner787 wrote:I know there are some MAX customers that have yet to take delivery of their new jets ,
Alaska for instance..... Might AS decide to cancel their MAX orders , especially since they
now have A321NEOS on property. I would also guess Lion Air might be reconsidering
their Max order book as well.
Not likely that there are any contractual clauses to justify deferrals or cancellations on 737 MAX orders based on thuis defect.
Let’s be very clear. The defect was the AOA probe, not the airplane design.
iahcsr wrote:Question; Was/is this software change listed in the Max maintenance manuals that techops use and simply not referenced in flightops manuals? This wasn’t a deliberate attempt to hide the information. Someone(s) at Boeing (And FAA?) just thought it wasn’t worth mentioning. The saying “Hindsight is 20/20” clearly applies here. This event is so eerily similar to the crash of a NZ A320 some years ago. In that case the AOA also failed and software did what it thought was the right thing.
ScottB wrote:Otherwise we would have seen the A330 TC suspended as a result of AF 447 given that the BEA pointed to the Human Computer Interface of the A330 being a potential contributing factor to the loss of that aircraft.
02:13:40 (Robert) Climb... climb... climb... climb...
02:13:40 (Bonin) But I've had the stick back the whole time!
[At last, Bonin tells the others the crucial fact whose import he has so grievously failed to understand himself.]
02:13:42 (Captain) No, no, no… Don’t climb… no, no.
02:13:43 (Robert) Descend, then… Give me the controls… Give me the controls!
[Bonin yields the controls, and Robert finally puts the nose down. The plane begins to regain speed. But it is still descending at a precipitous angle. As they near 2000 feet, the aircraft's sensors detect the fast-approaching surface and trigger a new alarm. There is no time left to build up speed by pushing the plane's nose forward into a dive.
boerje wrote:PSAatSAN4Ever wrote:Once again, I will point out that we have been through this before: December 27, 1991, SK 751. Despite following all procedures correctly, the flight crew discovered that every time they reduced engine power, something was reversing their actions and turned the thrust up. Every time they reduced, the thrust returned higher, until it burned up the engines and left the plane a glider. Fortunately in that incident, everyone survived. The cause of the engine surges? A piece of software McDonnell Douglas installed to prevent stalling that they didn't tell SAS about. The pilot of that flight never flew again, not being able to trust an airplane ever again.
SAS had been informed about Automatic Thrust Restoration (ATR).
"However, ATR was described in manuals by the aircraft manufacturer which every operator is obliged to know. Even though the system was developed for use in procedures not applied by SAS, a sufficiently careful study of the manuals should have led to SAS noting the system and training its pilots in its function."
https://en.wikipedia.org/wiki/Scandinavian_Airlines_Flight_751
https://www.havkom.se/assets/reports/English/C1993_57e_Gottrora.pdf
BoeingGuy wrote:...
Let’s be very clear. The defect was the AOA probe, not the airplane design.
iahcsr wrote:Question; Was/is this software change listed in the Max maintenance manuals that techops use and simply not referenced in flightops manuals? This wasn’t a deliberate attempt to hide the information. Someone(s) at Boeing (And FAA?) just thought it wasn’t worth mentioning. The saying “Hindsight is 20/20” clearly applies here. This event is so eerily similar to the crash of a NZ A320 some years ago. In that case the AOA also failed and software did what it thought was the right thing.
fadecfault wrote:I've reposted this a few times but here it is again
Here is the procedure for Runaway trim from my companies MAX QRH. The revision Date is July 2017.
1 Control column. . . . . . . . . . . . . . . . . Hold firmly
2 Autopilot (if engaged) . . . . . . . . . . . . .Disengage
Do not re-engage the autopilot.
Control aircraft pitch attitude manually with
control column and main electric trim as
needed.
3 Autothrottle (if engaged). . . . . . . . . . .Disengage
Do not re-engage the autothrottle.
4 If the runaway stops after the autopilot is
disengaged.
■ ■ ■ ■
5 If the runaway continues after the autopilot is
disengaged:
STAB TRIM CUTOUT
switches (both) . . . . . . . . . . . . . . . . CUTOUT
If the runaway continues:
Stabilizer
trim wheel . . . . . . . . . . Grasp and hold
6 Stabilizer . . . . . . . . . . . . . . . . . . . Trim manually
7 Anticipate trim requirements.
- - - - - - - - - - - - - -
That procedure WILL stop MCAS or any trim from operating the trim motor. MCAS is also described in my MAX maintenance training manuals.
N14AZ wrote:ScottB wrote:Otherwise we would have seen the A330 TC suspended as a result of AF 447 given that the BEA pointed to the Human Computer Interface of the A330 being a potential contributing factor to the loss of that aircraft.
??? Where did you read this?
The final words of the AF447-crew pretty much summarize what went wrong:02:13:40 (Robert) Climb... climb... climb... climb...
02:13:40 (Bonin) But I've had the stick back the whole time!
[At last, Bonin tells the others the crucial fact whose import he has so grievously failed to understand himself.]
02:13:42 (Captain) No, no, no… Don’t climb… no, no.
02:13:43 (Robert) Descend, then… Give me the controls… Give me the controls!
[Bonin yields the controls, and Robert finally puts the nose down. The plane begins to regain speed. But it is still descending at a precipitous angle. As they near 2000 feet, the aircraft's sensors detect the fast-approaching surface and trigger a new alarm. There is no time left to build up speed by pushing the plane's nose forward into a dive.
PSAatSAN4Ever wrote:boerje wrote:PSAatSAN4Ever wrote:Once again, I will point out that we have been through this before: December 27, 1991, SK 751. Despite following all procedures correctly, the flight crew discovered that every time they reduced engine power, something was reversing their actions and turned the thrust up. Every time they reduced, the thrust returned higher, until it burned up the engines and left the plane a glider. Fortunately in that incident, everyone survived. The cause of the engine surges? A piece of software McDonnell Douglas installed to prevent stalling that they didn't tell SAS about. The pilot of that flight never flew again, not being able to trust an airplane ever again.
SAS had been informed about Automatic Thrust Restoration (ATR).
"However, ATR was described in manuals by the aircraft manufacturer which every operator is obliged to know. Even though the system was developed for use in procedures not applied by SAS, a sufficiently careful study of the manuals should have led to SAS noting the system and training its pilots in its function."
https://en.wikipedia.org/wiki/Scandinavian_Airlines_Flight_751
https://www.havkom.se/assets/reports/English/C1993_57e_Gottrora.pdf
Page 72 of the report, point 2.2.3: "At the time of the accident there was no knowledge of ATR (Automatic Thrust Recovery) within SAS. The pilots were therefore not trained on ATR and information was not included in their operational documentation". It further states that if they had been trained, they would have switched settings and recovered. In this case, SAS' training did not include this particular setting, leading to the accident. That to me seems to be what happened in the Lion Air accident, where a change by the manufacturer was not passed on sufficiently to the pilots.
seahawk wrote:True, and the "facts" we currently have don't make any sense. No matter what else was happening, any pilot would pull back on the yoke when the nose starts pointing down. This of course leaves a stall as the possible cause for the descent, but how can a 737 flying on a level altitude at over 300kts stall? Next we have to consider an overspeed stall, which seemingly could only have come about as a result of unchallenged nose down flight; so we are back to why wouldn't a pilot pull back on the stick.It is all speculation until we have all facts.
seahawk wrote:Yes, even panicked pilots don't usually fail to pull back on the stick.It would be strange if only the failure of MCAS caused the crash, as pilots should be able to handle it,
seahawk wrote:We already have multiple sensors failure: airspeed and AOA.but we must consider the possibility of multiple sensor or system failures and then things might get complicated.
boerje wrote:Scandinavian Airlines Flight 751
ATR was described in manuals by the aircraft manufacturer
Lion Air Flight 610
MCAS was not described in manuals by the aircraft manufacturer
salttee wrote:
How about if we make all future airline pilot candidates demonstrate the ability to make a half hour flight in a Cessna 140 without a functioning airspeed indicator or altimeter?
I do not know the reason why it may not have been in the flight crew training but MCAS is performing a similar function as speed trim. This is not a totally different system. I do not know what pilots were trained but both the NG and MAX QRH calls for stab cutout to be enabled. NOT to pull back the column like Mr.Bjorn Fehrm says.
BoeingGuy wrote:Let’s be very clear. The defect was the AOA probe, not the airplane design.
kalvado wrote:Make sure you cut off 80% Cessna's stabilizer before that test flight - it would be a better approximation to the situation at hand. MCAS is there for reduced stability reasons.
djm18 wrote:I am guessing that with all that was going on in the cockpit in those short minutes the pilots never imagined that this was creeping up on them until it was too late. In other words, it would seem to me that they may have never considered (or had time) going through the runaway trim procedure which may have led them to a different outcome."
WIederling wrote:A defective AoA probe exposed the basic design error Boeing made. And apparently some rather grave omissions.
djm18 wrote:I do not know the reason why it may not have been in the flight crew training but MCAS is performing a similar function as speed trim. This is not a totally different system. I do not know what pilots were trained but both the NG and MAX QRH calls for stab cutout to be enabled. NOT to pull back the column like Mr.Bjorn Fehrm says.
I am guessing that with all that was going on in the cockpit in those short minutes the pilots never imagined that this was creeping up on them until it was too late. In other words, it would seem to me that they may have never considered (or had time) going through the runaway trim procedure which may have led them to a different outcome."
djm18 wrote:I do not know the reason why it may not have been in the flight crew training but MCAS is performing a similar function as speed trim. This is not a totally different system. I do not know what pilots were trained but both the NG and MAX QRH calls for stab cutout to be enabled. NOT to pull back the column like Mr.Bjorn Fehrm says.
I am guessing that with all that was going on in the cockpit in those short minutes the pilots never imagined that this was creeping up on them until it was too late. In other words, it would seem to me that they may have never considered (or had time) going through the runaway trim procedure which may have led them to a different outcome."
You don't need "procedures" to tell you to pull back on the yoke when the plane starts to nose down.
Sooner787 wrote:I know there are some MAX customers that have yet to take delivery of their new jets ,
Alaska for instance..... Might AS decide to cancel their MAX orders , especially since they
now have A321NEOS on property. I would also guess Lion Air might be reconsidering
their Max order book as well.
glideslope wrote:Desperately need to find and recover the CVR.
salttee wrote:In Lion 610 the airspeed was high and the attitude was level (at the start to the downward pitch). The rest of your post isn't worth responding to. It's as if you're a non-pilot who came over here from non-av just to argue.GalaxyFlyer wrote:You don't need "procedures" to tell you to pull back on the yoke when the plane starts to nose down.
Pulling back maybe the worst thing to do when the nose starts down! It depends on lots of other factors—speed, attitude being the primary ones. Pull a plane straight up, it will run out of airspeed, flop over nose down at a very similar attitude it had going up, now down with no airspeed. Pull and it will stall.
GF
boerje wrote:PSAatSAN4Ever wrote:boerje wrote:Lion Air Flight 610
MCAS was not described in manuals by the aircraft manufacturer
iahcsr wrote:Question; Was/is this software change listed in the Max maintenance manuals that techops use and simply not referenced in flightops manuals? This wasn’t a deliberate attempt to hide the information. Someone(s) at Boeing (And FAA?) just thought it wasn’t worth mentioning. The saying “Hindsight is 20/20” clearly applies here. This event is so eerily similar to the crash of a NZ A320 some years ago. In that case the AOA also failed and software did what it thought was the right thing.
WkndWanderer wrote:Where are you getting that MCAS wasn't described or that Boeing delivered a plane without giving the customer information on how it worked? As another poster described, the MCAS is described in MAX maintenance manuals and procedures that address it are in at least some airline's MAX QRH's, do you think they just guessed?
Jon Weaks, president of the Southwest Airlines Pilots Association, said Monday the airline and the pilots “were kept in the dark.”
“We do not like the fact that a new system was put on the aircraft and wasn’t disclosed to anyone or put in the manuals,” he said in an interview. What’s more, he noted, Boeing and the Federal Aviation Administration have now warned “that the system may not be performing as it should.”
Early Saturday morning, Capt. Mike Michaelis, chairman of the safety committee of the Allied Pilots Association (APA) at American Airlines, sent out a message to pilots informing them of details Boeing had shared with the airline about this new 737 MAX system — called MCAS (Maneuvering Characteristics Augmentation System).
“This is the first description you, as 737 pilots, have seen,” the message from the pilots association at American reads. “It is not in the American Airlines 737 Flight Manual … nor is there a description in the Boeing FCOM (Flight Crew Operations Manual). It will be soon.”
