MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures
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Agreed. "appropriate responses to contradictory indications" 
The appropriate response is to design your systems so they don't give contradictory indications.
Given that there will be problems with sensors from time to time, the systems should hand over control to the pilot with "I don't know sir, what do you think?" (or "Alors, je ne sais pas. Merde!" depending on manufacturer). Not hysterical "WE'RE STALLING, WE'RE GOING TOO SLOW" warnings when the nose is pointing at the ground and airspeed increasing. Not warnings that are directly contrary to what is actually happening.
The appropriate response is to design your systems so they don't give contradictory indications.
Given that there will be problems with sensors from time to time, the systems should hand over control to the pilot with "I don't know sir, what do you think?" (or "Alors, je ne sais pas. Merde!" depending on manufacturer). Not hysterical "WE'RE STALLING, WE'RE GOING TOO SLOW" warnings when the nose is pointing at the ground and airspeed increasing. Not warnings that are directly contrary to what is actually happening.
When the automation looses situational awareness it MUST silence all alarms. except the one that says "You now have manual control envelope protections are disabled"
This matter is common from AF447 to these two MAX accidents
If the problem was 'just' MCAS the solution would be in place by now and the Max flying. If you take the view that MCAS was a Bandaid (sticking plaster) on an open wound then the issue is not how to get a bigger or better plaster, but what is neccessary to close the wound. To humble SLF, it seems the fundamental issue is not MCAS but the undesirable aerodynamic characteristics that required MCAS to meet the certification performance standard in the first place. However good the redesigned MCAS is, even with a third AOA probe and associated logic, those characteristics are still there. And if dealing with the failure case requires a procedure that a pilot (however well trained) cannot physically deliver (manual trim), then Boeing either have to play the 'it can't happen' card or make fundamental changes to the mechanical design of the aircraft.
My suspicion is Boeing are trying (and failing) to convince regulators that 'it can't happen' to avoid the massive delay and cost impact of mechanical design changes. And the FAA are more willing to be convinced than EASA, even though the latter (who cannot relish the prospect of a tit for tat certification war with the US) would like to be convinced. Unfortunately, there is no end to this yet in sight.
And once it is sorted, there is still the issue of the relationship between the FAA and Boeing and public confidence: what else did they miss, and have 'they' really fixed it? It will be an interesting test of the Xenophobia of Americans if (as Boeing and the FAA seem to accept) the Max is reintroduced to service in North America but not elsewhere.
By the way, regulatory capture is not just an issue for Americans, Boeing and the FAA: Grenfell Tower proved that beyond all reasonable doubt.
My suspicion is Boeing are trying (and failing) to convince regulators that 'it can't happen' to avoid the massive delay and cost impact of mechanical design changes. And the FAA are more willing to be convinced than EASA, even though the latter (who cannot relish the prospect of a tit for tat certification war with the US) would like to be convinced. Unfortunately, there is no end to this yet in sight.
And once it is sorted, there is still the issue of the relationship between the FAA and Boeing and public confidence: what else did they miss, and have 'they' really fixed it? It will be an interesting test of the Xenophobia of Americans if (as Boeing and the FAA seem to accept) the Max is reintroduced to service in North America but not elsewhere.
By the way, regulatory capture is not just an issue for Americans, Boeing and the FAA: Grenfell Tower proved that beyond all reasonable doubt.
Last edited by SLF3; 23rd Sep 2019 at 12:12. Reason: Spelling
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Originally Posted by PerPurumTonantes 
Agreed. "appropriate responses to contradictory indications"
The appropriate response is to design your systems so they don't give contradictory indications.
Agreed. "appropriate responses to contradictory indications" The appropriate response is to design your systems so they don't give contradictory indications.
Excellent conceptualization, phylosocopter: "When the automation loses situational awareness . . ."
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IIRC, it was bundled with the "AOA DISAGREE" annunciation option.
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A limited range of electromechanical instruments are normally provided as back-up; alternatively, electronic standby flight instrument displays may be provided. Standby systems are fed from independent power supplies and sensors to ensure continuity of operation in the event of main system failure.
Edit: AOA disagree was a tiny part of the primary flight display, not a big red screen that says ignore all spurious warnings...
The AOA indicator (dial) is practically worthless. For the genuine value that awareness of AOA might have, there are no procedures for its use, no requirement for its use, and with some exceptions of individual preference, out of a pilot’s instrument scan. Consider the accidents where truly essential elements of the basic T (e.g. airspeed) were apparently out of the flight crew’s scan.
The presence of an indicator or display does not necessarily equate to crew awareness, let alone reliance on it, no matter how valuable some think the parameter is.
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Yes, i think that's correct.
Just observing that he kept it above 5000 thorough all the antics.
Mentour's video was about the wheel, not the electric trim that was being used to counter MCAS.
And yes, I think he likely could have continued use of the electric trim switches for another 10 minutes.
No way to prove it, or disprove it. Simulators won't really tell especially now with so much known.
Just the feeling I get from the data available.
Agree hewas slowly loosing pitch, but can we extrapolate that forward?
He was maintaining altitude. I think he would have given a really long trim command at some point and got back to better pitch if he had stayed on the controls. He'd already worked out that he could stop MCAS (not knowing what it was). I think the increasing forces would have connected and he'd have made a bigger stab correction. I think he soon would have (or had the F/O) checked the actual stab position and put it back in the 6.5-7 region.
I don't know the units on the column forces in the plots but it is in the plots I've seen. Just gives a range of -50 to 100.
https://leehamnews.com/wp-content/up...-annotated.png
Instead, it appears after the F/O couldn't find anything useful in the QRH if went to look himself and the F/O failed to maintain the corrections the captain had been doing (5 short blips instead of 5-10 second activations)
The captain didn't do it because of fatigue, it was to look for answers, thinking he's find something the F/O missed. But he wrongly assumed the F/O would continue to counter MCAS like he had been doing. 20-25 seconds later he's pulling harder than the F/O ever did.
(There are still some oddities in the last 40-50 seconds if the trace. Why the split when the F/O took over? Why did the F/O's force drop so much when the captain rejoined him?)
Then there's the issue of elevator blowdown at the speed and altitude of these crashes. The elevator should have been able to counter full AND trim. Except the speed at the lower altitude reduced the elevator authority. Is that something the regulators should look at along with the trim wheel?
FDR, concur with you in #2514. Hoping the CVR transcripts will shed more light on how much he did realize and what was said in the handoff.
I didn't call for such exceptionalism.
I was observing the apparent exceptionalism of the JT610 captain and even specifically said I didn't fault the F/O for not being exceptional.
Have you seen Mentour Pilot's video on trim forces ?
I'm surprised you are saying the Captain could have continued for hundreds of seconds.
I'm surprised you are saying the Captain could have continued for hundreds of seconds.
And yes, I think he likely could have continued use of the electric trim switches for another 10 minutes.
No way to prove it, or disprove it. Simulators won't really tell especially now with so much known.
Just the feeling I get from the data available.
Agree hewas slowly loosing pitch, but can we extrapolate that forward?
He was maintaining altitude. I think he would have given a really long trim command at some point and got back to better pitch if he had stayed on the controls. He'd already worked out that he could stop MCAS (not knowing what it was). I think the increasing forces would have connected and he'd have made a bigger stab correction. I think he soon would have (or had the F/O) checked the actual stab position and put it back in the 6.5-7 region.
I don't know the units on the column forces in the plots but it is in the plots I've seen. Just gives a range of -50 to 100.
https://leehamnews.com/wp-content/up...-annotated.png
Instead, it appears after the F/O couldn't find anything useful in the QRH if went to look himself and the F/O failed to maintain the corrections the captain had been doing (5 short blips instead of 5-10 second activations)
The captain didn't do it because of fatigue, it was to look for answers, thinking he's find something the F/O missed. But he wrongly assumed the F/O would continue to counter MCAS like he had been doing. 20-25 seconds later he's pulling harder than the F/O ever did.
(There are still some oddities in the last 40-50 seconds if the trace. Why the split when the F/O took over? Why did the F/O's force drop so much when the captain rejoined him?)
Then there's the issue of elevator blowdown at the speed and altitude of these crashes. The elevator should have been able to counter full AND trim. Except the speed at the lower altitude reduced the elevator authority. Is that something the regulators should look at along with the trim wheel?
FDR, concur with you in #2514. Hoping the CVR transcripts will shed more light on how much he did realize and what was said in the handoff.
I didn't call for such exceptionalism.
I was observing the apparent exceptionalism of the JT610 captain and even specifically said I didn't fault the F/O for not being exceptional.
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[snip]
He was maintaining altitude. I think he would have given a really long trim command at some point and got back to better pitch if he had stayed on the controls. He'd already worked out that he could stop MCAS (not knowing what it was). I think the increasing forces would have connected and he'd have made a bigger stab correction. I think he soon would have (or had the F/O) checked the actual stab position and put it back in the 6.5-7 region.
[snip]
He was maintaining altitude. I think he would have given a really long trim command at some point and got back to better pitch if he had stayed on the controls. He'd already worked out that he could stop MCAS (not knowing what it was). I think the increasing forces would have connected and he'd have made a bigger stab correction. I think he soon would have (or had the F/O) checked the actual stab position and put it back in the 6.5-7 region.
[snip]
- I have not seen official text of what happened on the previous Lion flight where many folks claim was saved by a third crewmember. My opinion is we are hearing some urban legend with a touch of reality, but not much considering the AC did not mention turning off the trim switches, not the constant stick shaker.
Also Figure 7 on page 16.
https://reports.aviation-safety.net/...RELIMINARY.pdf
Later news reports mention the 3rd person, but it's not in anything official that I know of.
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It's documented in the preliminary report for JT610, pages 19 and 20, though it states the PIC noticed it.
Also Figure 7 on page 16.
https://reports.aviation-safety.net/...RELIMINARY.pdf
Later news reports mention the 3rd person, but it's not in anything official that I know of.
Also Figure 7 on page 16.
https://reports.aviation-safety.net/...RELIMINARY.pdf
Later news reports mention the 3rd person, but it's not in anything official that I know of.
Edit : found this
https://www.airlineratings.com/news/...e-third-pilot/
Last edited by Fly Aiprt; 23rd Sep 2019 at 17:57. Reason: Added link
But, as discussed above, one could argue that rather than adding value it was simply a smoke-and-mirrors tactic on the part of Boeing.
A bit more digging reveals that it's a little more complicated than that. The AOA DISAGREE annunciation worked as intended on the aircraft of operators who had opted for the PFD AoA indicator (a notable example being American Airlines), but was non-functional on aircraft without that option (i.e. most other airlines' aircraft).