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Third Pilots' Union Raises Concern About Boeing 737 Max Jet

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Re: Third Pilots' Union Raises Concern About Boeing 737 Max Jet

#11

Post by WalterBright »

VBprogrammer wrote: post #10
WalterBright wrote: post #9

Earlier quoted context omitted.

> Why hasn't the 737Max been grounded pending investigation? Because jumping to conclusions is not helpful. Let the NTSB do their job and find out what went wrong.

I'm almost certain that the solution in this case will be training. Almost exactly as you've said in another comment. The correct response to an commanded stabiliser movement is to set the stab trim switch to cutoff. Pilots will probably experience this failure mode in their next recurrent training. The accident is more than likely to be attributed to a system being added without sufficient guidance being added to th…

That does seem likely, but very often the eventual cause discovered by the NTSB was not what people initially thought it was.

It's still worthwhile to warn the pilots about uncommanded movement and reiterate what to do about it. At this point I doubt any 737 pilot doesn't know about this.

To add to your summation, I'd expect the mechanism's inability to detect a faulty angle-of-attack sensor needs addressing.

Re: Third Pilots' Union Raises Concern About Boeing 737 Max Jet

#12

Post by simion314 »

WalterBright wrote: post #9
dingaling wrote: post #4

Earlier quoted context omitted.

I have less ire for Boeing than I do the FAA. There was an interesting comment on airliners.net that the USSR operated new airliners on freight services for several years before putting them on passenger services. So far I've confirmed that for the Tu-154 trijet, for example, which flew freight for two years before taking a revenue passenger. But in the West there has always been a tension between certificating for s…

> Why hasn't the 737Max been grounded pending investigation? Because jumping to conclusions is not helpful. Let the NTSB do their job and find out what went wrong.

>Because jumping to conclusions is not helpful. Let the NTSB do their job and find out what went wrong

We are used from previous cases that aircrafts will get grounded until we are sure the airplane is not at fault. So why in the past this happened before the investigation was complete but in this case the risk is considered t be minimal? I am not saying that it is right or wrong but I want to understand the algorithm that is used to decide what to do in this cases.

Re: Third Pilots' Union Raises Concern About Boeing 737 Max Jet

#13

Post by sokoloff »

WalterBright wrote: post #7

The pilots would have seen the nose down action as an uncommanded stabilizer trim movement. The solution is to shut off the power to the stab trim. This would work and would require no knowledge of the stall avoidance mechanism.

Exactly this. Following the existing memory items and QRH checklist items taught to every 737 pilot is (very, very likely) enough to overcome this contemplated scenario of a runaway trim from a flaw in the stability system. (It's remotely possible that the crew holds no blame in that they followed the checklist properly and the cutout switches were defective or the checklist response was otherwise insufficient.)

Re: Third Pilots' Union Raises Concern About Boeing 737 Max Jet

#14

Post by userbinator »

cyberferret wrote: post #6
A2017U1 wrote: post #3

The preliminary investigation report is due out 29th Nov. Boeing is already being sued. A bit OT but how hasn't the cockpit voice recorder been found yet? It's been weeks while giving off a detectable ping and is in 30m of water, that's recreational level diving. You simply follow signal strength. Given the big economic hit that occurred last time when Indonesian carriers were banned from Europe you have to wonder wh…

I think I read somewhere that they are not getting the 'pings' from the Cockpit Voice Recorder like they did the Flight Data Recorder, which was recovered. I believe the force of impact, which was almost vertically nose down at high speed just caused such a shattering of the airplane that it might have fatally destroyed the CVR, or else driven it under many feet of mud and silt. Re: Your last point - I think this tim…

The CVR is mounted next to the FDR so they should search in approximately the same place, and it probably won't be damaged if the FDR wasn't. It's more likely to be buried, as you note.

Re: Third Pilots' Union Raises Concern About Boeing 737 Max Jet

#15

Post by sokoloff »

matt4077 wrote: post #8
dingaling wrote: post #4

Earlier quoted context omitted.

I have less ire for Boeing than I do the FAA. There was an interesting comment on airliners.net that the USSR operated new airliners on freight services for several years before putting them on passenger services. So far I've confirmed that for the Tu-154 trijet, for example, which flew freight for two years before taking a revenue passenger. But in the West there has always been a tension between certificating for s…

They have grounded aircraft before, so we know they aren't inherently opposed to that. I would tend to trust the FAA, given the rather impressive track record of aviation. The difference from "Oh, the humanity!" to today, where North America and Europe have entire years without fatalities is astonishing. It's even more impressive considering passenger-miles/p.a. increased by something like 3 or 4 orders of magnitude.…

> If you want to consider safety only, you or I or the Russians could come up with the trivial (and only correct) solution, which is to ban air travel.

This would be a safety failure. Banning air travel is overwhelmingly likely to increase transport fatalities. It would decrease air travel fatalities, but would not represent an increase in safety.

"The National Highway Traffic Safety Administration (NHTSA) supported the FAA's decision [to not require tickets for pax under 2 years old] based on current FAA and NHTSA studies that show a mandate could result in another 13 to 42 added family member fatalities over 10 years in highway accidents." - [0]

[0] - https://www.faa.gov/news/press_releases/news_story.cfm?conte...

Re: Third Pilots' Union Raises Concern About Boeing 737 Max Jet

#16

Post by gargravarr »

Okay, I've never sat in the cockpit of an aircraft, but the one thing I don't understand - if the nose of a plane suddenly drops, isn't the pilot's first instinct to pull back on the controls to raise it? From what I've read, in Boeing aircraft at least, the pilot's controls can always override the automatic systems.

Re: Third Pilots' Union Raises Concern About Boeing 737 Max Jet

#17

Post by ubernostrum »

simion314 wrote: post #12
WalterBright wrote: post #9

Earlier quoted context omitted.

> Why hasn't the 737Max been grounded pending investigation? Because jumping to conclusions is not helpful. Let the NTSB do their job and find out what went wrong.

>Because jumping to conclusions is not helpful. Let the NTSB do their job and find out what went wrong We are used from previous cases that aircrafts will get grounded until we are sure the airplane is not at fault. So why in the past this happened before the investigation was complete but in this case the risk is considered t be minimal? I am not saying that it is right or wrong but I want to understand the algorith…

We are used from previous cases that aircrafts will get grounded until we are sure the airplane is not at fault.

To be clear: you're suggesting that grounding an entire type of aircraft, either worldwide or even just within US airspace, is a common response to accidents?

I ask because the last general grounding of a type was in 2013 to remedy the 787 battery issues. Prior to that, the last such grounding was the DC-10 in 1979.

Re: Third Pilots' Union Raises Concern About Boeing 737 Max Jet

#19

Post by JshWright »

gargravarr wrote: post #16

Okay, I've never sat in the cockpit of an aircraft, but the one thing I don't understand - if the nose of a plane suddenly drops, isn't the pilot's first instinct to pull back on the controls to raise it? From what I've read, in Boeing aircraft at least, the pilot's controls can always override the automatic systems.

Pulling back on the controls moves small control surfaces (elevators) on the horizontal stabilizer (the "tail wing"). The way the anti-stall measure works on the MAX (and many other planes, to be fair) is by adjusting the pitch trim. Adjusting the trim changes the angle of the entire horizontal stabilizer.

https://en.wikipedia.org/wiki/Stabilizer_(aeronautics)#/medi...

It's very possible for the effect of the extreme trim condition to be more than the elevators can overcome. The pilot can certainly override the trim setting, but the issue here is that they weren't expecting that to change, since they weren't trained on the fact that the plane might do it automatically (in those flight conditions).

Here's a good video explaining how trim works (in normal operation) on a (slightly older) 737:

https://www.youtube.com/watch?v=l62NvkRWa5E

Re: Third Pilots' Union Raises Concern About Boeing 737 Max Jet

#20

Post by jsjohnst »

isostatic wrote: post #5

If it's Boeing, I 'aint going

“I’d rather be hit by a bus than fly in an Airbus”

There’s versions of these type of statements for all aircraft manufacturers. Does it add anything to the conversation to state them? Not in my opinion.

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