Another Southwest close call

[BugBear]

Originally Posted by EXDAC

I have not checked that it was exactly reproduced but the quoted text comes from the leaked report that was linked in post 9 of this thread.

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Apologies, should have researched myself. Keeping information like this secret is a crime, imo. Airframers and airlines have a ''Duty 0f Care"...

For all the public knows this could be MCAS.
MAX has a record of unresponsive controls in a seemingly spontaneous descent... It could be MCAS for all anyone knows. If it is, next charge against Boeing could be manslaughter...If PE, so be it, the public should know either way. Next time I fly, I'll take the "BUS"

"Company Memo..." Right

[FullWings]

I think the report on this one is going to be interesting reading, although from the account above it seems the PF lost control as soon as they initiated the GA, for reasons yet to be properly established, then the PM took a long time and a GPWS caution followed by a warning to work out that not all was well and intervene.

All of us have been in high workload situations but as a crew they do appear to have been a long way behind the aeroplane for quite a while. You had one job...

[Vessbot]

Originally Posted by BugBear

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It could be MCAS for all anyone knows.

That's only active with flaps up

[BugBear]

Originally Posted by Vessbot

That's only active with flaps up

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Fair Cop... However, we have an accident under investigation involving major spontaneous a/c commands based on "sensors"...also, wiring faults killing several hundred folks. Equipment occasionally fails. If failure is sourced back at the factory...well.

[EXDAC]

Originally Posted by Vessbot

Starting from AP/AT on, the AT advancing with TOGA is what normally happens. So I'd take it as the default assumption regardless of story trustworthiness.

Do we know that this was a coupled approach? If that was included in the leaked report I must have missed it.

[Vessbot]

Originally Posted by EXDAC

Do we know that this was a coupled approach? If that was included in the leaked report I must have missed it.

Being that the overwhelming majority of them are, when in IMC, yes probably it was.

[EXDAC]

Originally Posted by Vessbot

Being that the overwhelming majority of them are, when in IMC, yes probably it was.

Ok, lets assume AP was engaged in approach mode. Does this imply AT was also engaged? I don't know 737 modes but I keep going back to this quote -

Originally Posted by olster

PM should monitor thrust application which is also dependent on auto throttle engagement or not. First push should be enough for a reduced and sensible climb rate or approx 80 / 85 pc N1 dependent on variant.

Isn't it possible that AT was not engaged, PF pushed up the throttles and intended to activate TOGA but did not. PF then fixates on the PFD FD or HUD guidance cue and fails to maintain a scan of the FMA and raw data.

Is there anything in the available data that precludes that scenario?

[Nose Rider]

Originally Posted by Vessbot

Being that the overwhelming majority of them are, when in IMC, yes probably it was.

So many possible scenarios without knowing the facts. It's possible it was a coupled approach and prior to initiating the missed the FO clicked off the autopilot while leaving the autothrottle on.

[Vessbot]

Originally Posted by EXDAC

Ok, lets assume AP was engaged in approach mode. Does this imply AT was also engaged? I don't know 737 modes but I keep going back to this quote -
---begin---
PM should monitor thrust application which is also dependent on auto throttle engagement or not. First push should be enough for a reduced and sensible climb rate or approx 80 / 85 pc N1 dependent on variant.
---end---

It is physically possible for AP to be on without AT; but other than a deferred AT, or being in the middle (not beginning) of some mode confusion cluster**** episode, I would estimate this to be done approximately zero times in the history of 737's.

Practically speaking, the "or not" in the quote refers to the AP+AT both off state.

Isn't it possible that AT was not engaged, PF pushed up the throttles and intended to activate TOGA but did not. PF then fixates on the PFD FD or HUD guidance cue and fails to maintain a scan of the FMA and raw data.

Is there anything in the available data that precludes that scenario?

This seems very possible. If we're speculating, a similar one in my head is that they could have had the MCP set to the missed approach altitude, so the altitude immediately captured (or was already captured) so the FD quickly gave them a big fly-down.

[Vessbot]

Originally Posted by Nose Rider

So many possible scenarios without knowing the facts. It's possible it was a coupled approach and prior to initiating the missed the FO clicked off the autopilot while leaving the autothrottle on.

Yes. But even if the AP was not disconnected and simply TOGA was pressed at minimums, the same thing would have happened: AP turns off, AT stays on and advances to TOGA

(Earlier people mentioned dual channel approaches, in which the AP also stays on and flies the goaround, but this is only possible on an ILS where this approach is an RNAV).

[EXDAC]

Originally Posted by Vessbot

Yes, this would have come with an airspeed loss.

The aircraft levelled off and had a thrust setting that maintained speed. Why would manually advancing the throttles come with an airpeed loss? There was no climb.

Do we expect that there will ever be a public report? All I have heard is that FAA is investigating. I have not heard of any reason for NTSB to become involved.

[Vessbot]

Originally Posted by EXDAC

The aircraft levelled off and had a thrust setting that maintained speed. Why would manually advancing the throttles come with an airpeed loss? There was no climb.

Do we expect that there will ever be a public report? All I have heard is that FAA is investigating. I have not heard of any reason for NTSB to become involved.

I misread your post (as saying they forgot to push the throttles up at all.... just like flying, "slow is smooth, smooth is fast" goes for reading!), and have edited mine already.

[Sailvi767]

Originally Posted by BugBear

You have not used quotation marks, and the text is written in third person, A cite would be delightful

Its a direct quote from the memo released to SWA pilots.

[Nose Rider]

Originally Posted by EXDAC

The aircraft levelled off and had a thrust setting that maintained speed. Why would manually advancing the throttles come with an airpeed loss? There was no climb.

Do we expect that there will ever be a public report? All I have heard is that FAA is investigating. I have not heard of any reason for NTSB to become involved.

I would not expect any additional info to be made public from the FAA or SWA.

[Rozy1]

Originally Posted by Vessbot

It is physically possible for AP to be on without AT; but other than a deferred AT, or being in the middle (not beginning) of some mode confusion cluster**** episode, I would estimate this to be done approximately zero times in the history of 737's.

Actually, for most of Southwest’s 53 year history, autopilot usage without auto throttles was the norm. A/T use is relatively new.

[BugBear]

Sailv

Originally Posted by Sailvi767

Its a direct quote from the memo released to SWA pilots.

With respect, you are quoting from a memo filtered ("interpreted") through FlightOps, the Union, legal, and engineering. Include Boeing, and is "quoting" the flight crew.
All solids removed via filtration...with Boeing's record of intimidation, there were implied threats.

No pilot would use "inadvertent", which implies he was not in control of his actions...the reported flight profile is not possible in a large commercial jet airliner. It describes JetLOC

CapnBloggs int the only one having nightmares

[Vessbot]

Originally Posted by Rozy1

Actually, for most of Southwest’s 53 year history, autopilot usage without auto throttles was the norm. A/T use is relatively new.

I should have qualified with "NG and later." Is this true, even then? If so, I stand corrected. Maybe it's too much other-operator-perspective warping my view, but it's hard to imagine.

[Lookleft]

Given that neither pilot seems to have any idea what was happening why would you trust a statement that the autothrottle advanced the throttles? Isn't it normal practice to manually advance the throttles while activating TOGA?

I don't know what the 787 has for TOGA activation but on the 737,767,747 to engage the A/T in TOGA mode there are two buttons just forward of the thrust lever hand holds (or whatever the top of the thrust levers are called) that must be pressed to advance the thrust levers to TOGA and the G/A mode on the FMA. On the 737 the first push gives 2000'/min the second gives full thrust. If the F/O had pressed TOGA at the start then the FD would have given him guidance to keep climbing. I can't recall what the A/T does if the TOGA buttons are not pressed but I am assuming it will be trying to maintain the selected speed. If the F/O started to climb at the minima without advancing the T/L then the A/T would have advanced enough to maintain the selected speed. The F/O probably perceived this as an excessive pitch up and pushed forward on the control column leading to the descent to the water. If the TOGA buttons had been pressed at the minima there is very little likelihood of the F/O having the physical strength to push the nose below the horizon unless he used the trim buttons and held them in the forward position. If you assume that TOGA was engaged at the start, and he ignored the FD, and he was strong enough to get the nose below the horizon then the RoD would have been a lot higher than 4000'/min, I doubt there would have been a recovery from the dive. The 8500'/min RoC at the end of the G/A oscillations suggests thats when the TOGA buttons were pressed.

[BugBear]

Vessbot

Vessbot. So what happens when go around is selected and the Flaps have been left out 15 degrees. With power coming up, and the FO feels the Nose get light, could he have pushed too hard?
Thinking over rotation, could MCAS deploy? His saturation level as high as it was, could he have Retracted Flaps then gotten as alarmed with Pitch Rate down and then pulled back? With unexpected MCAS deployment, well, talk about saturation. Seeing the FO's mess, was Captain as unsure of the flight path as PF?

The "leaked report" gains credibility for having been "leaked". ... Coming upon a leaked report should raise doubts as to its credibility for those used to technical explanations...

It reads like a seventh grade book report....
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[MechEngr]

It's not a "report." It's an internal memo "To: All Pilots." from the Southwest Director Flight Safety Programs & Assurance.

Perhaps 7th grade is ... is the ice thin over here? I think it says what it needs to say in a way that avoids differential equations and Navier–Stokes equations.

Presuming MCAS is given the correct AoA it will add the correct amount of trim to provide the correct control column feel. AFAIK it will be a smooth, continuous adaptation to pitch and speed.