Boeing 737 800 MAX

[Busher]

Economy and issues like that cannot be considered in such cases. Agencies like FAA and EASA should take these decisions solely based on safety.

I'm sorry Sir but safety is not an absolute.
We takeoff now in freeing precipitation because modern de-ice and anti-ice sprays make it safer.
We fly in the vicinity of thunderstorms because both airborne and ground based radars make it safer.
I could go on and on with examples but you noticed I used the word "safer" not "safe".
Limiting the discussion to aviation, you cannot fly nor can you decide not to fly without considering all the repercussions.

[DmonSlyr]

Ive missed you and your theories.

Even Einstein was a theorist!

It's the "we don't want you to dig too deep into our corruption so we will name call and write off your understanding with a simple term, and laugh at how the masses agrees with us who didn't even have to prove the "theorist" wrong with actual facts.".

Theories can be facts, but facts cannot be theories. 

[Toad]

Sheesh.

[Oldman731]

When your jet starts doing funky stuff you press the quick disconnect button and hold it, pitch/power/performance to a safe condition, and call for the appropriate abnormal checklist, a concept these Children of the Magenta don't seem to grasp.

To a humble GA pilot, the procedure seems more involved than that:

This bulletin directs flight crews to existing procedures to address this condition. In the event of erroneous AOA data, the pitch trim system can trim the stabilizer nose down in increments lasting up to 10 seconds. The nose down stabilizer trim movement can be stopped and reversed with the use of the electric stabilizer trim switches but may restart 5 seconds after the electric stabilizer trim switches are released. Repetitive cycles of uncommanded nose down stabilizer continue to occur unless the stabilizer trim system is deactivated through use of both STAB TRIM CUTOUT switches in accordance with the existing procedures in the Runaway Stabilizer NNC. It is possible for the stabilizer to reach the nose down limit unless the system inputs are counteracted completely by pilot trim inputs and both STAB TRIM CUTOUT switches are moved to CUTOUT.

Additionally, pilots are reminded that an erroneous AOA can cause some or all of the following indications and effects:

- Continuous or intermittent stick shaker on the affected side only.
- Minimum speed bar (red and black) on the affected side only.
- Increasing nose down control forces.
- Inability to engage autopilot.
- Automatic disengagement of autopilot.
- IAS DISAGREE alert.
- ALT DISAGREE alert.
- AOA DISAGREE alert (if the AOA indicator option is installed)
- FEEL DIFF PRESS light.

In the event an uncommanded nose down stabilizer trim is experienced on the 737 - 8 / - 9, in conjunction with one or more of the above indications or effects, do the Runaway Stabilizer NNC ensuring that the STAB TRIM CUTOUT switches are set to CUTOUT and stay in the CUTOUT position for the remainder of the flight.

https://arstechnica.com/information-technology/2018/11/indonesia-737-crash-caused-by-safety-feature-change-pilots-werent-told-of/

I'm willing to concede that this would not seem unusual to a veteran 737 pilot.  But I did notice that Boeing has rushed to make a software change:

Boeing Co. BA -6.15% is making an extensive change to the flight-control system in the 737 MAX aircraft involved in October’s Lion Air crash in Indonesia, going beyond what many industry officials familiar with the discussions had anticipated.

The change was in the works before a second plane of the same model crashed in Africa last weekend—and comes as world-wide unease about the 737 MAX’s safety grows."

https://www.wsj.com/articles/boeing-to-make-key-change-in-max-cockpit-software-11552413489

If there were no concern about the software, this might seem to be a waste of time and money.  But hey, maybe it's a publicity stunt!

- oldman

[saggs]

This 100%. It baffles me you guys in here just want a potentially dangerous aircraft flying around. I don’t care about anything but the lives of people. Ground the jet. Fix it move on no more lives lost.

I'm not gonna get involved in the ground or not-ground argument. (But I know the FAA will not hesitate to do so if/when it finds a valid reason.)

Just wanted to pop in and say as someone who makes a living maintaining and fixing aircraft, that ALL aircraft are "potentially dangerous" from the biggest airliner to the tiniest utlra-light.  Every one of them goes high enough and/or fast enough to kill you.

The good news is the the commercial air travel/cargo industry has done such a great job at mitigating that potential danger, that flying halfway around the world is statistically orders of magnitude safer then driving to the local supermarket.

[Busher]

To a humble GA pilot, the procedure seems more involved than that:

This bulletin directs flight crews to existing procedures to address this condition. In the event of erroneous AOA data, the pitch trim system can trim the stabilizer nose down in increments lasting up to 10 seconds. The nose down stabilizer trim movement can be stopped and reversed with the use of the electric stabilizer trim switches but may restart 5 seconds after the electric stabilizer trim switches are released. Repetitive cycles of uncommanded nose down stabilizer continue to occur unless the stabilizer trim system is deactivated through use of both STAB TRIM CUTOUT switches in accordance with the existing procedures in the Runaway Stabilizer NNC. It is possible for the stabilizer to reach the nose down limit unless the system inputs are counteracted completely by pilot trim inputs and both STAB TRIM CUTOUT switches are moved to CUTOUT.

Additionally, pilots are reminded that an erroneous AOA can cause some or all of the following indications and effects:

- Continuous or intermittent stick shaker on the affected side only.
- Minimum speed bar (red and black) on the affected side only.
- Increasing nose down control forces.
- Inability to engage autopilot.
- Automatic disengagement of autopilot.
- IAS DISAGREE alert.
- ALT DISAGREE alert.
- AOA DISAGREE alert (if the AOA indicator option is installed)
- FEEL DIFF PRESS light.

In the event an uncommanded nose down stabilizer trim is experienced on the 737 - 8 / - 9, in conjunction with one or more of the above indications or effects, do the Runaway Stabilizer NNC ensuring that the STAB TRIM CUTOUT switches are set to CUTOUT and stay in the CUTOUT position for the remainder of the flight.

https://arstechnica.com/information-technology/2018/11/indonesia-737-crash-caused-by-safety-feature-change-pilots-werent-told-of/

I'm willing to concede that this would not seem unusual to a veteran 737 pilot.  But I did notice that Boeing has rushed to make a software change:

Boeing Co. BA -6.15% is making an extensive change to the flight-control system in the 737 MAX aircraft involved in October’s Lion Air crash in Indonesia, going beyond what many industry officials familiar with the discussions had anticipated.

The change was in the works before a second plane of the same model crashed in Africa last weekend—and comes as world-wide unease about the 737 MAX’s safety grows."

https://www.wsj.com/articles/boeing-to-make-key-change-in-max-cockpit-software-11552413489

If there were no concern about the software, this might seem to be a waste of time and money.  But hey, maybe it's a publicity stunt!

- oldman

Actually its not that complicated. Powered Stabs for manual and mach trim have been around for many years. Automatic stab operation for stall protection is fairly new.
BUT, I was trained along with every pilot I flew with that any abnormal behaviour of the pitch trim system was an immediate autopilot disengagement, stab trim switch(es) to CUTOUT, and hand-fly the airplane to the nearest suitable airport.
The NTSB investigation will determine from both the CVR and FDR if the issue was abnormal behaviour in the pitch control systems and if so, it will also determine if proper remedial actions were taken.

[Vraciu]

To a humble GA pilot, the procedure seems more involved than that:

This bulletin directs flight crews to existing procedures to address this condition. In the event of erroneous AOA data, the pitch trim system can trim the stabilizer nose down in increments lasting up to 10 seconds. The nose down stabilizer trim movement can be stopped and reversed with the use of the electric stabilizer trim switches but may restart 5 seconds after the electric stabilizer trim switches are released. Repetitive cycles of uncommanded nose down stabilizer continue to occur unless the stabilizer trim system is deactivated through use of both STAB TRIM CUTOUT switches in accordance with the existing procedures in the Runaway Stabilizer NNC. It is possible for the stabilizer to reach the nose down limit unless the system inputs are counteracted completely by pilot trim inputs and both STAB TRIM CUTOUT switches are moved to CUTOUT.

<MUNCH>


If there were no concern about the software, this might seem to be a waste of time and money.  But hey, maybe it's a publicity stunt!

- oldman

What Busher said. 

You stop the trim system and then DEACTIVATE it. 

In the Embraer we have a nice red Quick Disconnect button by our thumb that stops ALL TRIM, YAW DAMPER, STALL PROTECTION, AND AUTOPILOT FUNCTIONS.    You then disable the affected system through the cutout buttons for Primary & Backup Trim (Elevator), cutout buttons for Stall Protection (Stick Shaker and Stick Pusher), or System 1 & 2 Shutoff buttons (Aileron or Rudder) before releasing the QD.   

It’s a no-brainer.

https://www.bangaloreaviation.com/wp-content/uploads/2014/04/VT-AOK_Embraer_Legacy_600_DSC_8376_WM.jpg - Captain’s Quick Disconnect

http://farm3.static.flickr.com/2476/3936171704_e97eb29932.jpg - Aileron/Rudder

http://farm3.static.flickr.com/2451/3935388923_f4687cf7d4.jpg - Elevator/Stall Protection


On the Boeing it’s not much different frankly. 


That said, everything after the Embraer 145 (and possibly the Embraer 170) has been designed to be too cute by half. 

[Puma44]

Actually its not that complicated. Powered Stabs for manual and mach trim have been around for many years. Automatic stab operation for stall protection is fairly new.
BUT, I was trained along with every pilot I flew with that any abnormal behaviour of the pitch trim system was an immediate autopilot disengagement, stab trim switch(es) to CUTOUT, and hand-fly the airplane to the nearest suitable airport.
The NTSB investigation will determine from both the CVR and FDR if the issue was abnormal behaviour in the pitch control systems and if so, it will also determine if proper remedial actions were taken.

Exactly this vs hysteric knee jerk reactions by the inexperienced and uninformed.

[Shuffler]

This 100%. It baffles me you guys in here just want a potentially dangerous aircraft flying around. I don’t care about anything but the lives of people. Ground the jet. Fix it move on no more lives lost.

By the same token the pilots of that airline may be undertrained. Ground them out of over precaution, fix it, then continue on.

Problem still is that we do not know.

[Puma44]

I get it now. It all makes sense. puma and Vraciu have stock in Boeing. Sorry for messing up your guys dividends!!

Actually, I don’t.  Another WAG (Wild A_ _ Guess).

[Shuffler]

Actually, I don’t.  Another WAG (Wild A_ _ Guess).

Looked more like a KJR (Knee Jerk Reaction) but WAG works too.   

[Puma44]

 

[zack1234]

I remember when the Yanks were all over the Rolls Royce engines when they turned into fireworks and when BP polluted the entire American coastline (New Jersey never noticed)

If we were meant to fly planes would still be made in Britain

[Oldman731]

Actually its not that complicated. Powered Stabs for manual and mach trim have been around for many years. Automatic stab operation for stall protection is fairly new.
BUT, I was trained along with every pilot I flew with that any abnormal behaviour of the pitch trim system was an immediate autopilot disengagement, stab trim switch(es) to CUTOUT, and hand-fly the airplane to the nearest suitable airport.

Good to know, and glad to hear it!

...but...so why the sudden "extensive change to the flight control system"?

- oldman

[Vraciu]

Good to know, and glad to hear it!

...but...so why the sudden "extensive change to the flight control system"?

- oldman

Because non-US operators are incapable of pushing the correct buttons.   Hey, it's no more ridiculous than the other silly assertions by some in here.