Go Back  PPRuNe Forums > Flight Deck Forums > Rumours & News
Reload this Page >

Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed

Rumours & News Reporting Points that may affect our jobs or lives as professional pilots. Also, items that may be of interest to professional pilots.

Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed

Old 29th Apr 2019, 21:15
  #821 (permalink)  
 
Join Date: Jan 2008
Location: Reading, UK
Posts: 10,642
Originally Posted by andycba View Post
Are you sure? Is this not only for the MAX10 at this point? However, if the geometry is the same it could be certified for use on the rest of the MAX range...
Correct, it's only for the Max 10, as I acknowledged when my error was pointed out at the time, a couple of months ago.

Originally Posted by DaveReidUK View Post
Thanks, you're right of course.
DaveReidUK is offline  
Old 29th Apr 2019, 21:18
  #822 (permalink)  
 
Join Date: Dec 2002
Location: UK
Posts: 1,844
Mr O,
why not just disable MCAS?’
Which is part of Boeing’s proposed modification. https://www.boeing.com/commercial/73...e-updates.page

If this is so, then why is there need for training above knowledge of the system and aircraft limitations without MCAS.
safetypee is offline  
Old 29th Apr 2019, 22:22
  #823 (permalink)  
 
Join Date: Dec 2015
Location: Cape Town, ZA
Age: 57
Posts: 378
Originally Posted by safetypee View Post
Mr O,
why not just disable MCAS?’
Which is part of Boeing’s proposed modification. https://www.boeing.com/commercial/73...e-updates.page

If this is so, then why is there need for training above knowledge of the system and aircraft limitations without MCAS.
IMO the story is something like Catch 22:
- MCAS is needed to meet certification requirements, but it will rarely be activated, and if there is AOA disagree then MCAS will be inhibited, but the conditions under which AOA disagree occurs are only rarely encountered in the normal flight envelope.
- Boeing must test all of this, and the FAA must verify all of this, and the airlines should understand all of this, and pilots should have some knowledge and awareness of this.
- It is not necessary for each pilot to train for this on a simulator, since it is extremely unlikely to activate, and the average pilot would not actually notice the difference when MCAS activated, and would not have to take any action other than the normal control inputs.
Unless it fails in some way, which is still the elephant in the room...
GordonR_Cape is offline  
Old 29th Apr 2019, 22:29
  #824 (permalink)  
 
Join Date: Mar 2015
Location: Washington state
Posts: 149
Originally Posted by safetypee View Post
Mr O,
why not just disable MCAS?’
Which is part of Boeing’s proposed modification. https://www.boeing.com/commercial/73...e-updates.page

If this is so, then why is there need for training above knowledge of the system and aircraft limitations without MCAS.


Because although the failure is less likely (perhaps far less likely) it is still possible. An MCAS failure once every five years is still an unacceptable risk given how many people can be killed.

There is also the question of how well we really understand the cause of the failure; many times in my experience there another factor beyond the obvious ones. Given that there have been two additional programming (?) errors disclosed (the AOA disagree warning did not work, and some other "minor" control surface issue surfaced) it really feels like the MAX is still in beta and pilots had better be trained in all the worst case scenarios.

Boeing wants to have their cake and eat it too -- the crashes were caused by improperly trained pilots, but no more pilot training is needed! That does not make me want to fly "B" again.
Water pilot is offline  
Old 30th Apr 2019, 12:57
  #825 (permalink)  
 
Join Date: Dec 2002
Location: UK
Posts: 1,844
Gordon,

Water pilot, life, aviation, are probabilities.
MCAS failures must not occur in future operations - where ‘must not’ is the level of probability required for certification. This level is the internationally accepted value for equivalent safety - as low as reasonably achievable, but like all risk some small probability remains.

There is greater safety benefit in considering the wider system; thus tail trim can move to unacceptably high values - trim runaway, structural failure, … Then the important question is if pilot intervention will be able to reduce the risk; can the situation be recognised (any alerting), can the procedure be followed, is action physically possible, time available, level of knowledge / training required, … all balanced against risk - cost effectiveness.

A point can be reached where the situation is unacceptable, then the design must be changed; thence consideration of a ‘fully’ protected system, e.g. triplex FBW, but which also has a demonstrated manual backup.

It is this argument which rejects the need for specific MCAS training; although the trim runaway case probably still does. However, because the latter safety case depends pilot intervention, and with evidence from these accidents, there is the suggestion that pilot intervention is ineffective - it cannot be guaranteed.

You and others cite training - low professional standards. Alternatively, consider that the circumstances of the situation could be beyond pilot comprehension, an ambiguous emergency procedure, physically impossible to execute, … all beyond reasonable human ability. Also, if ‘reasonable’ is viewed as a probability, then this too cannot be established due ‘being human’, which even with training, cannot be sufficiently guaranteed to use in a system safety case.
safetypee is offline  
Old 30th Apr 2019, 14:44
  #826 (permalink)  
 
Join Date: Dec 2001
Location: Brisvegas
Posts: 2,721
MCAS failures must not occur in future operations
The MCAS did not fail. It did exactly what it was expected to do. The issue was that it was sent erroneous data from the AoA vane. There is where the weak link lies. A single failed vane was able to trigger a "correct" response from MCAS.
MCAS does not need fixing, the data supplied to it needs to be robustly cross checked or discarded.
Icarus2001 is offline  
Old 30th Apr 2019, 15:49
  #827 (permalink)  
 
Join Date: Jan 2011
Location: Seattle
Posts: 632
Originally Posted by Icarus2001 View Post
The MCAS did not fail.
Technically, the MCAS software did not fail. But from an overall systems standpoint, it did. The software people may get off the hook for writing code that ran per the specification. But the spec missed an important failure mode. And was written for the wrong level of system criticality.

When I worked at Boeing, we had a number of instances where the hardware people finished their design (or were saddled with older systems for which a derivative needed to be produced given a limited budget and schedule). And once finished it got "thrown over the wall" to the software group. in part because hardware and software were (and still may be) viewed as two completely different kinds of design domains. It was up to the coders to develop something that 'worked', given the hardware peoples' attitude that remaining shortcomings could always be fixed in software.

It's a cultural problem (and not just at Boeing) that has always been way above my pay grade to fix. Even if I could see it.
EEngr is offline  
Old 30th Apr 2019, 16:04
  #828 (permalink)  
 
Join Date: Mar 2018
Location: Central UK
Posts: 283
Originally Posted by Water pilot View Post

Boeing wants to have their cake and eat it too -- the crashes were caused by improperly trained pilots, but no more pilot training is needed! That does not make me want to fly "B" again.
WP, that argument is completely irrational.

If pilots were improperly trained its absolutely nothing to do with Boeing. How can it be? They merely make aeroplanes and specify the training required to operate them safely. If a customer fails to train their pilots properly you can't blame Boeing, they had nothing to do with it.
Unless they were trained at Renton of course...
"No more training is needed for pilots who were properly trained in the first place" - does that satisfy you?

Otherwise you'd be blaming Ford for training failures in a crash when someone on the other side of the world with a photoshopped licence has gone joyriding- which is equivalent to your original statement.

meleagertoo is offline  
Old 30th Apr 2019, 16:10
  #829 (permalink)  
 
Join Date: Nov 2000
Location: Canada
Posts: 335
If the MAX is not flying soon

Another possible impact of the MAX grounding.GE Aviation maintains output amid Max crisis and warns of Q2 hit

  • 30 April, 2019
  • SOURCE: Flight Dashboard
  • BY: Jon Hemmerdinger
  • Boston
The grounding of the Boeing 737 Max has not yet significantly impacted the profits of engine maker GE Aviation, though General Electric’s chief executive warns of a potential financial impact in the second quarter.

Meanwhile, GE Aviation’s CFM International joint venture has continued to produce 737 Max Leap-1B engines at previous rates despite Boeing slowing its own production.

Speaking during the company’s first quarter earnings call on 30 April, GE chief executive Lawrence Culp says the grounding could affect GE Aviation equally to its CFM partner Safran Aircraft Engines.

Just days ago, Safran’s top brass warned the grounding could cost it €200 million ($224 million) in the second quarter.

“We probably have something in that same range as a headwind with respect… to our own side of the [CFM joint venture] in the second quarter,” GE’s Culp says.

The grounding “presents a new risk” he adds. “We have strong partnership with Boeing. We are confident in the 737 Max aircraft [and] we are working closely with Boeing.”

So far, GE Aviation’s production has hummed along unaffected even though in April Boeing cut 737 output by 19% to 42 aircraft monthly.

“We have not changed our engine production plan at this time, but the timing of cash flows may be impacted by collection of receivables from Boeing, depending on when aircraft deliveries resume,” says GE chief financial officer Jamie Miller.

Evendale, Ohio-based GE Aviation shipped 424 Leap engines in the first quarter, more than twice as many as in the same period of 2018. It shipped 751 commercial aviation engines of all models in the first quarter, up 15% from 651 shipments in the same period one year earlier, GE reports.

GE Aviation’s first quarter profit inched up 4% year-over-year to $1.7 billion, while revenue jumped 13% to $8.0 billion. Revenue from sales of equipment such as engines increased 24% in the quarter to $3.1 billion, while aircraft services revenue increased 4% to $4.8 billion.

The aviation unit’s first quarter profit margin slipped 1.6 percentage points year-over-year to 20.9%, GE reports. The decline primarily reflects fewer deliveries of higher-profit CFM56 engines and more deliveries of new-generation Leap engines, says Miller.

GE Aviation has been behind on Leap deliveries for months amid supply chain pressures. Earlier this year, executives said deliveries were four weeks behind schedule.

But GE Aviation has made up lost ground. It is now on schedule with Airbus and two weeks behind with Boeing, says Culp.

“We expect to be back on schedule in the second quarter,” he adds.
Longtimer is offline  
Old 30th Apr 2019, 23:34
  #830 (permalink)  
 
Join Date: Mar 2005
Location: N/A
Posts: 2,802
Quote from Boeing site.
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
Am I just a worry wart? Boeing put in a system (MCAS) to ensure certifiable handling characteristics approaching the stall, yet crews will not receive sim training on approaches to the stall with MCAS disabled. Gotta be a gotcha there?
megan is offline  
Old 1st May 2019, 00:01
  #831 (permalink)  
568
 
Join Date: Aug 2002
Location: Castletown
Posts: 67
Originally Posted by meleagertoo View Post
WP, that argument is completely irrational.

If pilots were improperly trained its absolutely nothing to do with Boeing. How can it be? They merely make aeroplanes and specify the training required to operate them safely. If a customer fails to train their pilots properly you can't blame Boeing, they had nothing to do with it.
Unless they were trained at Renton of course...
"No more training is needed for pilots who were properly trained in the first place" - does that satisfy you?

Otherwise you'd be blaming Ford for training failures in a crash when someone on the other side of the world with a photoshopped licence has gone joyriding- which is equivalent to your original statement.
Renton no longer have the simulators to train customer airline pilots, Miami does the training, albeit with contract instructors.

Last edited by 568; 1st May 2019 at 00:18. Reason: text
568 is offline  
Old 1st May 2019, 00:23
  #832 (permalink)  
 
Join Date: Feb 2018
Location: Canberra
Posts: 0
Originally Posted by meleagertoo View Post
Otherwise you'd be blaming Ford for training failures in a crash when someone on the other side of the world with a photoshopped licence has gone joyriding- which is equivalent to your original statement.
If Ford designed a hidden system that would randomly and aggressively steer your car into the oncoming traffic, it would certainly be a problem with Ford, not the driver.
Dee Vee is offline  
Old 1st May 2019, 01:31
  #833 (permalink)  
 
Join Date: Jul 2013
Location: Australia
Posts: 151
Originally Posted by Thrust Augmentation View Post
$$$$$$$!

Heck' it seems that sims are now too $$$$$$$$.
A large part of the cost will be that Boeing is the only source of the mechanics and physics of how the sim is to work. They turn $$$$ to $$$$$$$$. If they wanted to reduce the price of a sim significantly they could.
RickNRoll is offline  
Old 1st May 2019, 01:56
  #834 (permalink)  
 
Join Date: Mar 2002
Location: Florida
Posts: 5,114
Originally Posted by Dee Vee View Post
If Ford designed a hidden system that would randomly and aggressively steer your car into the oncoming traffic, it would certainly be a problem with Ford, not the driver.
That's why the driver has a steering wheel and brakes, just in case the front end loses a single bolt
lomapaseo is offline  
Old 1st May 2019, 05:51
  #835 (permalink)  
 
Join Date: Dec 2015
Location: Cape Town, ZA
Age: 57
Posts: 378
Originally Posted by megan View Post
Quote from Boeing site.Am I just a worry wart? Boeing put in a system (MCAS) to ensure certifiable handling characteristics approaching the stall, yet crews will not receive sim training on approaches to the stall with MCAS disabled. Gotta be a gotcha there?
The assumption must be that Boeing have done extensive flight tests (preliminary and more recently), to measure under maximum yaw (single engine operation, cross-winds, etc), that AOA disagree is within certain limits. IMO the 5.5 degrees threshold is not an arbitrary number, nor an FAA mandate, but based on actual aerodynamics.

If they have not done this work, the FAA could never certify the revised MCAS. Presumably the test details will emerge sometime soon. If not, doubt would remain about the validity of the flight envelope.
GordonR_Cape is offline  
Old 1st May 2019, 06:14
  #836 (permalink)  
 
Join Date: Dec 2002
Location: UK
Posts: 1,844
Originally Posted by lomapaseo View Post
That's why the driver has a steering wheel and brakes, just in case the front end loses a single bolt
But the bolt fell out of the steering
Whereas steering systems should have greater redundancy, reliability, and enable some control, even after a minor, sub system, single failure.
As should aircraft enable pitch control, and not require two people and three hands to follow a procedure.


Gordon

safetypee is offline  
Old 1st May 2019, 11:53
  #837 (permalink)  
 
Join Date: Dec 2014
Location: Schiphol
Posts: 331
During the discussions some posters mentioned LAM. One poster indicated it was present in his NG to MAX differences training. Does anyone have a short description of its design considerations, functionality, operational use, and training explanation ?
Note: This is for contextual understanding only, I am not suggesting this function had anything to do with these accidents in specific terms.
A0283 is offline  
Old 1st May 2019, 17:18
  #838 (permalink)  
 
Join Date: Dec 2015
Location: Cape Town, ZA
Age: 57
Posts: 378
In case anyone missed it, AvHerald posted a copy of a long list of 25 questions submitted to the FAA/FSB. Many of these touch on technical issues discussed in great detail in this thread: Crash: Ethiopian B38M near Bishoftu on Mar 10th 2019, impacted terrain after departure

For example, one of my pet issues:
10 - Did the certification consider a massive change in the function of the AoA when MCAS (as actor in the flight controls) was introduced in addition to stick shaker (monitoring only)?
GordonR_Cape is offline  
Old 1st May 2019, 18:13
  #839 (permalink)  
 
Join Date: Jan 2008
Location: Reading, UK
Posts: 10,642
Originally Posted by GordonR_Cape View Post
In case anyone missed it, AvHerald posted a copy of a long list of 25 questions submitted to the FAA/FSB. Many of these touch on technical issues discussed in great detail in this thread: Crash: Ethiopian B38M near Bishoftu on Mar 10th 2019, impacted terrain after departure

For example, one of my pet issues:
Presumably this latest list of questions will get the same WTF response from the FAA that a similar questionnaire from Avherald elicited after the Lion Air preliminary report - probably not helped by asking questions that 2 minutes with Google would have answered, like "when was the Max 8 certificated?" [March 8, 2017].
DaveReidUK is offline  
Old 1st May 2019, 19:54
  #840 (permalink)  
 
Join Date: Mar 2015
Location: Washington state
Posts: 149
Originally Posted by meleagertoo View Post
WP, that argument is completely irrational.

If pilots were improperly trained its absolutely nothing to do with Boeing. How can it be? They merely make aeroplanes and specify the training required to operate them safely. If a customer fails to train their pilots properly you can't blame Boeing, they had nothing to do with it.
Unless they were trained at Renton of course...
"No more training is needed for pilots who were properly trained in the first place" - does that satisfy you?

Otherwise you'd be blaming Ford for training failures in a crash when someone on the other side of the world with a photoshopped licence has gone joyriding- which is equivalent to your original statement.
No, as somebody who wants to reach my destination alive that does not satisfy me at all. There is no evidence presented that these pilots were not trained to industry standards. If you say that we need to ground all aircraft until we can test that pilots are trained to new standards, have at it -- I'm sure the FAA would be open to your suggestion. If you want to say "put all MAX pilots in the sim and ensure that they are trained to handle trim runaway properly" then that would be a good step forward, but Boeing (and presumably Southwest) does not want to do that.

So you are left, as a passenger, with a rather difficult safety determination to make. I have no way of determining the skill of the pilot (if you think that ethnicity or "culture" matters, may I remind you of Colgan Air flight 3407).

Sorry if I have touched a nerve here, I am not trying to troll you. But when I board an aircraft my goal is to make it to my destination alive, and the system that I am using consists of both the plane and the pilot.

There has been no evidence presented that the pilots were in any way more deficient in training or skills than any other pilot. There has been no evidence that the seven different pilots who were fooled by this system were flying with counterfeit licenses, or that they paid off somebody to get their license, or that they were not trained. (Seven pilots because even the jump seat pilot who averted the first crash apparently had no idea why they had just saved the plane, given that they turned the power trim back on briefly after disabling it.)

On the other hand, there is evidence that the plane can sneakily point its nose towards the ground in certain very predictable failure modes (flappy things hanging on the outside of an aircraft in -40c weather do go wrong sometimes) and that the pilots are expected to notice this behavior quickly and channel their inner Wilbur Wright by turning off the newfangled electric motors and hand pulling wheels that pull cables, all the while pointing the nose of the plane at the ground and reducing airspeed. Given a choice, I would rather fly on a plane that doesn't put its pilots in that situation, or if it is proven to have done so is one where the company steps up, admits the problem, and fixes it.

Boeing's reluctance to admit that there even was a problem is a big problem in itself -- having worked for organizations that have from time to time made major boo-boos (without killing anybody that I know of) I can tell you that when the internal environment is "there really was no problem, it was all customer error and we are just going through the motions for the public's sake" then the problem will not get fixed. The guy who says "uh oh" is quickly squelched by exactly the same sort of arguments that I see here. Now I realize that a hell of a lot of money is relying on a fix, which is why I don't trust it. "Failure is not an option" never applies to engineering.
Water pilot is offline  

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.