Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed
Join Date: Dec 2015
Location: Cape Town, ZA
Age: 62
Posts: 424
Likes: 0
Received 0 Likes
on
0 Posts
Easier and more efficient to start with a clean-sheet design. See: https://en.wikipedia.org/wiki/Boeing...dsize_Airplane
Makes me wonder if either or both crews were thinking of this QRH stall recovery information in their attempts to find a stable attitude+power combination:
Initiate the recovery:
• Hold the control column firmly.
• Disengage autopilot and disconnect autothrottle.
• Smoothly apply nose down elevator to reduce the angle of attack until buffet or stick
shaker stops. Nose down stabilizer trim may be required
(My bold)
Then there is this warning which follows:
WARNING: *If the control column does not provide the needed
response, stabilizer trim may be necessary. Excessive
use of pitch trim may aggravate the condition, or may result in loss
of control or in high structural loads.
RegardingMr Elwell: In his testimony he refered to the aisle stand switches as trim actuation switches, which they are not, and additionally described the 737 incorrectly as FBW. He's a Trump appointee trotted out to mouth platitudes in order to keep actual experts as far from the committee as possible.
Initiate the recovery:
• Hold the control column firmly.
• Disengage autopilot and disconnect autothrottle.
• Smoothly apply nose down elevator to reduce the angle of attack until buffet or stick
shaker stops. Nose down stabilizer trim may be required
(My bold)
Then there is this warning which follows:
WARNING: *If the control column does not provide the needed
response, stabilizer trim may be necessary. Excessive
use of pitch trim may aggravate the condition, or may result in loss
of control or in high structural loads.
RegardingMr Elwell: In his testimony he refered to the aisle stand switches as trim actuation switches, which they are not, and additionally described the 737 incorrectly as FBW. He's a Trump appointee trotted out to mouth platitudes in order to keep actual experts as far from the committee as possible.
And for that very pertinent matter, why does the MCAS have the apparent ability to trim the stabiliser to the point stridently warned against in the QRH?
Join Date: Mar 2015
Location: North by Northwest
Posts: 476
Likes: 0
Received 0 Likes
on
0 Posts
And further, why did Boeing not adopt the same philosophy as used in its KC-46 version of MCAS - any pilot control column input shuts MCAS or its derivative down.
Join Date: Dec 2015
Location: Cape Town, ZA
Age: 62
Posts: 424
Likes: 0
Received 0 Likes
on
0 Posts
1. AFAIK the certification requirements and mission objectives for military and passenger aircraft are rather different.
2. Allowing pilot input to override MCAS would invalidate specific certification requirements.
3. Several recent crashes (both Airbus and Boeing) indicate that pilots can do unexpected things in a loss-of-control situation (night/IMC), and assuming that pilot control inputs are always correct is definitely not a good idea.
4. Military pilots have been trained to deal with AOA, and to interpret AOA disagree. It is clear than many civilian pilots do not use AOA, and have not been trained to deal with AOA disagree.
I already answered that question somewhere yesterday (can't find the link).
1. AFAIK the certification requirements and mission objectives for military and passenger aircraft are rather different.
2. Allowing pilot input to override MCAS would invalidate specific certification requirements.
3. Several recent crashes (both Airbus and Boeing) indicate that pilots can do unexpected things in a loss-of-control situation (night/IMC), and assuming that pilot control inputs are always correct is definitely not a good idea.
4. Military pilots have been trained to deal with AOA, and to interpret AOA disagree. It is clear than many civilian pilots do not use AOA, and have not been trained to deal with AOA disagree.
1. AFAIK the certification requirements and mission objectives for military and passenger aircraft are rather different.
2. Allowing pilot input to override MCAS would invalidate specific certification requirements.
3. Several recent crashes (both Airbus and Boeing) indicate that pilots can do unexpected things in a loss-of-control situation (night/IMC), and assuming that pilot control inputs are always correct is definitely not a good idea.
4. Military pilots have been trained to deal with AOA, and to interpret AOA disagree. It is clear than many civilian pilots do not use AOA, and have not been trained to deal with AOA disagree.
Join Date: Mar 2015
Location: North by Northwest
Posts: 476
Likes: 0
Received 0 Likes
on
0 Posts
I already answered that question somewhere yesterday (can't find the link).
1. AFAIK the certification requirements and mission objectives for military and passenger aircraft are rather different.
2. Allowing pilot input to override MCAS would invalidate specific certification requirements.
3. Several recent crashes (both Airbus and Boeing) indicate that pilots can do unexpected things in a loss-of-control situation (night/IMC), and assuming that pilot control inputs are always correct is definitely not a good idea.
4. Military pilots have been trained to deal with AOA, and to interpret AOA disagree. It is clear than many civilian pilots do not use AOA, and have not been trained to deal with AOA disagree.
1. AFAIK the certification requirements and mission objectives for military and passenger aircraft are rather different.
2. Allowing pilot input to override MCAS would invalidate specific certification requirements.
3. Several recent crashes (both Airbus and Boeing) indicate that pilots can do unexpected things in a loss-of-control situation (night/IMC), and assuming that pilot control inputs are always correct is definitely not a good idea.
4. Military pilots have been trained to deal with AOA, and to interpret AOA disagree. It is clear than many civilian pilots do not use AOA, and have not been trained to deal with AOA disagree.
- Flight control system will now compare inputs from both AOA sensors. If the sensors disagree by 5.5 degrees or more with the flaps retracted, MCAS will not activate. An indicator on the flight deck display will alert the pilots.
- If MCAS is activated in non-normal conditions, it will only provide one input for each elevated AOA event. There are no known or envisioned failure conditions where MCAS will provide multiple inputs.
- MCAS can never command more stabilizer input than can be counteracted by the flight crew pulling back on the column. The pilots will continue to always have the ability to override MCAS and manually control the airplane.
WRT 4, How many gauges will be added to provide data to pilots that automation currently takes care of behind the scene before civilian pilot overload? How many automation override capabilities will be provided? As you point out, ex-military are trained but has the workload for the civilian corps just been increased where another mistake might occur?
The below also taken from Boeing's site:
"There are no pilot actions or procedures during flight which require knowledge of angle of attack"
To be clear, the KC-46, basic aircraft, control system, A/P, etc were certified to Part 25, not military specs. Only the military pieces were certified by the military. But the basic design architecture of the 767 and 737 are decades apart and the amendment level of Part 25 which applied (certification basis) are quite different from the 737. I don't know for sure how the architectures of the flight control system, sensor data flows, trim system of the two models are alike, but expect significant differences with respect to how the MCAS operates. We'll see.
I'm staying pretty much out of this now - I've had some 'off the record' discussions with people 'in the know' - so I now know more than I can publicly discuss. However I can say most of posts related to certification are seriously lacking in accuracy.
The second half of that is not correct. Per the Changed Product Rule, any new or changed system on the MAX (or the commercial cert of the 767-2C/KC-46) must step up to the latest revision levels of the regulations (there are exceptions, but they are rare and not applicable to MCAS). So you'll find the cert basis for MCAS is pretty much the same between the MAX and the KC-46. That doesn't mean they work the same way or are intended to do the same thing.
I'm staying pretty much out of this now - I've had some 'off the record' discussions with people 'in the know' - so I now know more than I can publicly discuss. However I can say most of posts related to certification are seriously lacking in accuracy.
I'm staying pretty much out of this now - I've had some 'off the record' discussions with people 'in the know' - so I now know more than I can publicly discuss. However I can say most of posts related to certification are seriously lacking in accuracy.
Join Date: Apr 2008
Location: Paris
Age: 74
Posts: 275
Likes: 0
Received 0 Likes
on
0 Posts
The second half of that is not correct. Per the Changed Product Rule, any new or changed system on the MAX (or the commercial cert of the 767-2C/KC-46) must step up to the latest revision levels of the regulations (there are exceptions, but they are rare and not applicable to MCAS). So you'll find the cert basis for MCAS is pretty much the same between the MAX and the KC-46. That doesn't mean they work the same way or are intended to do the same thing.
I'm staying pretty much out of this now - I've had some 'off the record' discussions with people 'in the know' - so I now know more than I can publicly discuss. However I can say most of posts related to certification are seriously lacking in accuracy.
I'm staying pretty much out of this now - I've had some 'off the record' discussions with people 'in the know' - so I now know more than I can publicly discuss. However I can say most of posts related to certification are seriously lacking in accuracy.
I think this shows a difficulty - certification procedures are supposed to be public.
How can the public trust a certification process if it is "confidential" between an aircraft manufacturer and a certification authority which is delegating authority to the manufacturer?
Edmund
Edmund
I think this shows a difficulty - certification procedures are supposed to be public.
How can the public trust a certification process if it is "confidential" between an aircraft manufacturer and a certification authority which is delegating authority to the manufacturer?
Edmund
Edmund
How can the public trust a certification process if it is "confidential" between an aircraft manufacturer and a certification authority which is delegating authority to the manufacturer?
Edmund
Edmund
I'm made several posts on the cert process on the half dozen threads related to the 737 MAX - it's like talking to a wall and had no noticeable effect on the number of farcically ill-informed cert related posts. So I decided to stop wasting my time...
Last edited by tdracer; 1st Apr 2019 at 04:10.
Join Date: Apr 2008
Location: Paris
Age: 74
Posts: 275
Likes: 0
Received 0 Likes
on
0 Posts
When I mentioned I know more than I can publicly discuss, I was referring to the accident investigation, not cert. As I've posted many, many times, information regarding an accident investigation is only to be made public by the lead investigators.
I'm made several posts on the cert process on the half dozen threads related to the 737 MAX - it's like talking to a wall and had no noticeable effect on the number of farcically ill-informed cert related posts. So I decided to stop wasting my time...
I'm made several posts on the cert process on the half dozen threads related to the 737 MAX - it's like talking to a wall and had no noticeable effect on the number of farcically ill-informed cert related posts. So I decided to stop wasting my time...
I am afraid that at this point in the negotiations between various countries, airlines and Boeing and the US agencies, the general public has about as much faith in the "investigation reports" for the Max as in the "certification paperwork". Sorry about that, public confidence is the first casualty once people start explaining how bad it would be if *facts* were published. That is why Airbus and AirFrance had to go to extreme lengths to recover the AF447 orange boxes, and why in the end blame got apportioned to everybody and no one protested from Airbus - for bad pitots specced and airspeed disagree badly managed in software, the management for not replacing pitots, and pilots for not handflying the plane - any amount of blame was preferable to a suspicion that something was left unsaid.
There is an old joke - sunlight is the best disinfectant. Rather than rant about how dumb and badly informed the public and media are, why not just make all the certification documentation and recovered data from the accidents public, including the flight recorders and the documentation supplied by Boeing to the airlines ?
When it takes the President himself to issue a grounding order, as the last country to do so, the last thing anyone will now expect from the FAA is impartiality or honesty.
Edmund
Edmund
There are very defined and strict rules regarding accident investigations. ALL public information releases MUST come the investigating authorities (in this case the Indonesian and Ethiopian agencies). This is nothing new, those rules have been in place for decades. I was involved in some investigations before I retired (the major one being the Lauda 767 T/R deployment in-flight) - and I was directed not to talk to anyone who didn't have a need to know. Violating that could result in serious disciplinary action - up to and including getting fired. I'm not about to the endanger the career of a friend by posting information that was discussed with me in confidence. The Lauda investigation was hard on me - it was obvious early on Boeing had messed up - and not being able to talk to people about it just made it worse. Rumor is there has been at least one suicide attempt among the MAX engineering ranks. This stuff isn't easy, those aren't mindless robots who designed and certified it. We're talking about real people, and they are taking it very, very seriously.
Ask yourself, how long did it take after the AF447 boxes were recovered before the results were publicly released? It took months. The job of the investigators is to determine what what wrong and how to keep it from happening again - not to feed public curiosity or to try the case in the the court of public opinion.
The results of these accident investigations will be published - along with such things as the voice recorder transcripts and FDR data. I'm sure the story of how the cert went wrong and why will be front and center. The process takes time - it's easy to sit behind your keyboard and criticize but you're not the one tasked with getting it right.
If you want to know how the cert process works, start by reading this thread:
Of modern airliner certification
I worked with the FAA for nearly 30 years before I retired - they aren't perfect (nor is EASA) - they are made up of humans and humans are not perfect. I've certainly seen flaws with the way the FAA and EASA do things - one of the biggest is that they have a tendency to miss the forest because they are too busy examining the trees - they often miss the big picture.
There are very defined and strict rules regarding accident investigations. ALL public information releases MUST come the investigating authorities (in this case the Indonesian and Ethiopian agencies). This is nothing new, those rules have been in place for decades. I was involved in some investigations before I retired (the major one being the Lauda 767 T/R deployment in-flight) - and I was directed not to talk to anyone who didn't have a need to know. Violating that could result in serious disciplinary action - up to and including getting fired. I'm not about to the endanger the career of a friend by posting information that was discussed with me in confidence. The Lauda investigation was hard on me - it was obvious early on Boeing had messed up - and not being able to talk to people about it just made it worse. Rumor is there has been at least one suicide attempt among the MAX engineering ranks. This stuff isn't easy, those aren't mindless robots who designed and certified it. We're talking about real people, and they are taking it very, very seriously.
Ask yourself, how long did it take after the AF447 boxes were recovered before the results were publicly released? It took months. The job of the investigators is to determine what what wrong and how to keep it from happening again - not to feed public curiosity or to try the case in the the court of public opinion.
The results of these accident investigations will be published - along with such things as the voice recorder transcripts and FDR data. I'm sure the story of how the cert went wrong and why will be front and center. The process takes time - it's easy to sit behind your keyboard and criticize but you're not the one tasked with getting it right.
If you want to know how the cert process works, start by reading this thread:
Of modern airliner certification
I worked with the FAA for nearly 30 years before I retired - they aren't perfect (nor is EASA) - they are made up of humans and humans are not perfect. I've certainly seen flaws with the way the FAA and EASA do things - one of the biggest is that they have a tendency to miss the forest because they are too busy examining the trees - they often miss the big picture.
Join Date: Dec 2015
Location: Cape Town, ZA
Age: 62
Posts: 424
Likes: 0
Received 0 Likes
on
0 Posts
1. Suggestions such as installing a 3rd AOA vane so that the flight control computers can vote on the output?
2. My response that certification requirements to such changes will be costly and time consuming?
Do you mean you have stopped responding to #1 or #2, or both? Or do you mean stability requirements certification, such as elevator feel? Or all of them?
Pegase Driver
Join Date: May 1997
Location: Europe
Age: 74
Posts: 3,684
Likes: 0
Received 0 Likes
on
0 Posts
tdracer, very well put .
on this :
this is unfortunately valid for many organisations as we have decided to slice the forest into bits and each tree has now his own experts and specialists, which often do not communicate much with one another. And the person in charge of the forest is in fact just listening to experts of individual trees .
I have also seen this reverse thinking , we have a goal or a paragdim , so give me the scientific facts to prove it is feasible and that I am right. And among the trees you always will find an expert with the solution you like ..
on this :
one of the biggest is that they have a tendency to miss the forest because they are too busy examining the trees - they often miss the big picture.
I have also seen this reverse thinking , we have a goal or a paragdim , so give me the scientific facts to prove it is feasible and that I am right. And among the trees you always will find an expert with the solution you like ..
Join Date: Aug 2017
Location: UK
Posts: 206
Likes: 0
Received 0 Likes
on
0 Posts
Apart from the two aircraft involved in the tragic loss of life are there other known instances of MCAS misbehaving?
I ask because with the best part of 400 aircraft in service one would have thought there would have been more events?
I ask because with the best part of 400 aircraft in service one would have thought there would have been more events?
Not to step on anyone's toes and waste your time. Can you clarify a point for me, following my recent response to some some farcical posts, where my response included interpretation of certification requirements. Do you mean:
1. Suggestions such as installing a 3rd AOA vane so that the flight control computers can vote on the output?
2. My response that certification requirements to such changes will be costly and time consuming?
Do you mean you have stopped responding to #1 or #2, or both? Or do you mean stability requirements certification, such as elevator feel? Or all of them?
1. Suggestions such as installing a 3rd AOA vane so that the flight control computers can vote on the output?
2. My response that certification requirements to such changes will be costly and time consuming?
Do you mean you have stopped responding to #1 or #2, or both? Or do you mean stability requirements certification, such as elevator feel? Or all of them?
My comments regarding farcical posts have to do with statements such as 'Boeing is self certified' and 'everyone else just rubber stamps the FAA approval', or 'the cert requirements for the MAX are from 1967' - all of which are demonstrably false (read the thread I linked in the previous post for some detail). People who have not been involved in aircraft certification simply have no idea of what's involved and how it works (or, occasionally, doesn't work).
I've made several posts where I explained this, but apparently no one reads them...
