https://www.avweb.com/avwebflash/news/Pilots-Not-Told-About-737-MAX-Auto-Trim-System-231846-1.html

Boeing kept airlines and pilots in the dark about an automated background trim system on the 737 MAX that may be implicated in the first crash of the new model in Indonesia last month. The trim system, which is meant to improve pitch characteristics and stall protection, wasn t even described in any of the documentation provided to pilots on the new aircraft.

Hardware, Pilots training and manuals
not aligned. It seem unbeliveable.

I say the flight crews must always be able to hand fly the airplane.. turn off automation and fly the plane.. and if Boeing failed to disclose, train about a new AOA sys.. whew... look out..

I am guessing there are more things aircrews do not know with these new automated crafts, it seems like the designers are hiding unfavorable stalling characteristics of the craft due to the larger engines, from my studies in aerodynamics possibly due to a sharper drop off in lift due to the higher wetted area of the engines or rapid separation of the airflow at higher AOAs, just speculating but explained in detail by the Wiz engineer at Boeing.

Based on the AA pilots description, it appears that more description of the airplanes systems and handling should have been specified somewhere. In my opinion it falls on Boeing for not documenting this and their protection system did a disservice, looks like pilotless planes are not coming anytime soon.

What were Boeing designers thinking? Use STABILISER to prevent stall? Are they aware that stabilisers are extremely powerful compared to elevators? So does the system automatically stop stabiliser movement if pilot pulls control column back? I think we need more input from actual B737 Max pilots to know what the heck is going on.

Boeing said. “We are confident in the safety of the 737 MAX. Safety remains our top priority.”
That's comforting!

To those whom are pointing the finger at automation and the pilots don’t know what happened here. As Jeff Lawson stated ,it was in the new background trim system. It had nothing to do with indications or pushover. Once this system rolled forward (at very fast speed) the stabilator lost authority and could not overcome the pitch down force and setting. Ten men pulling would not recover it. The descent rate in this case was in excess of 30k FPM. Also, the Max does not have a trim brake like other Guppy’s.

Something seems to have been lost amongst all of the paranoid anti corporate fear mongering conspiracy theorists. Lion Air is a horrible airline with poor maintenance, poor pilots and a horrible safety record. They failed to repair a malfunctioning AOA system and released an unairworthy airplane piloted by poorly trained pilots. Just like Air France 447, this started with a faulty probe and was mishandled by pilots who proceeded to fly a perfectly controllable aircraft into the water.

A function of the flight control computer, the MCAS activates when an aircraft’s angle of attack (AOA) exceeds a certain threshold based on airspeed and altitude readings, pushing the nose down to reduce the risk of a stall. The system operates only when the autopilot is off, flaps are up and during steep turns. It resets when the AOA falls below the threshold or pilots provide manual horizontal stabilizer trim commands.



Not part of previous 737 designs, the system is a feature of new MAX series airliners, Boeing has acknowledged. But the MCAS is not covered in the MAX flight crew operations manual (FCOM) or in difference training instructions for pilots of earlier 737NGs, operators have noted.



Boeing has issued an FCOM bulletin to 737 MAX operators warning that erroneous AOA data trigger automatic nose-down inputs and emphasizing that pilots follow specific procedures to keep the aircraft from descending uncommanded. The FAA mandated the action in a Nov. 7 emergency airworthiness directive.

This is a well-researched and interesting article. Could those who are knowledgable about transport category airplanes (and specifically 737s) please comment on the following: It is my understanding that many airplanes have a "stick pusher" function to prevent a stall; is the MAX different in that it uses nose down trim achieve this? Also, am I wrong in assuming that getting close to the point where any stall prevention mode would activate is the result of an egregious failure by a flight crew?

I have been flying (pilot) for 44 years. My frequent flyer number with Southwest Airlines is 25 years old. I will not fly on a 737 MAX, Southwest knows this. It is difficult to get model of aircraft from Southwest until you board. They change my flights. Boeing has not fixed anything, just changed procedures.

The other week a national late night radio host accused the mechanics at the airline of being responsible for the crash. It's too bad that big mouths with a large audience can spread so much misinformation.

First impression was something commanded the planes aactions other than the pilots. Previously a model of aircraft was grounded due to runaway trim. It's just something you have to suspect. Sadly you can figure with enough altitude and time to ditch the distraction of fighting the controls someone would of figured negate any trim automation and manual control. The landing automation in the Airbus A320's maiden flight crash where the computer stuck with reduced throttle and pitch not allowing a go around was a good example. Don't let the airplane get ahead of you is hard when automation sets you up for that situation. https://www.youtube.com/watch?v=YAg-WauGrLU

I see a giant Lawsuit coming sell your Boeing stock now !

Most new aircraft now have computers between the pilot and the airplane controls. In most cases these computers will prevent the pilot or the auto pilot to go beyond certain parameters for the safety of the aircraft. However in this case, Boeing has gone one step further and has programmed the flight control computers to not only override the pilot input but actually move the controls in a way to fly the plane, in spite of the pilot. This can be dangerous as seen here. And worst of all Boeing did not advise anyone of what it had done.

There are two big whirring trim wheels in the 737 cockpit. They were spinning like mad in this situation, screaming “turn me off!”. This is called runaway trim. The Boeing Manual calls for the following:

1. Grip and hold controls firmly.
2. Turn off Autopilot
3. If runaway continues, Trim cutout switches BOTH OFF.
4. Trim aircraft manually

At my airline this is not a memorized checklist but easily remembered. This situation was not insurmountable. Turning off the trim switches would have resolved this problem immediately. There a dozens of airlines that fly the new 737s. Most had trained properly.

Just read an article that states the stabilizer size compared to the elevator gives so much authority that it cannot be overridden in certain conditions. For example, if the stab trim is allowed to go to full nose down and as a result the aircraft goes in a steep dive and at very high speed, the aerodynamic loads on the stab will be so strong that it will be impossible for the pilot or the electrical motor to bring the stabilizer out of full nose down. Would be interesting to try this in the simulator

I'm not any sort of a pilot - except those 4 wheeled killer machines. I have learned my piloting them in the Milky Way School of Hard Knocks. I've been lucky so far. I haven't been killed, anyone.
You air pilots sometimes get caught in the learning too late class.

For a system change that critical not to be shared with the pilots is unacceptable to GROSSLY understate it.

Omg

What a nasty surprise that would be! Did Boeing purposefully decide not to inform operators of the change or did they fail to flight-test failure modes on this vital bit of equipment?

If it aint Boeing I aint going. Ohh woops, not the right thread for this childish rhyme is it. Maybe we can talk about how Boeing lets real manly men fly the plane with a real stick and Airbus doesn't let you have control over the plane. Woops, also the wrong thread. Hmm, maybe this isn't your father's Boeing anymore.

Pilots have a check list to use if there is a problem. If the change isn't in the friggin manual, that's not helpful. At least in healthcare, if there is a change, the end users get updated pages for their manuals, and usually a cover letter giving a brief explanations of the changes.

FLY THE F-ING AIRCRAFT AND NOT THE AUTOPILOT!

As is usually the case, many want to blame the airplane or the builder. The ultimate responsibility rests with the pilot to fly the plane, and counter for situations when the "holes in the swiss cheese" line up. You cannot replace with automation, good old-fashioned knowledge in flying. Don't believe it? Just ask Capt. Sullenberger!

Having flown the737 for many hours safely, just one question. If On autopilot an the aircraft starts doing funny things, can’t youturn the a/p offf and become a pilot again?

I suspect all this was covered in the conversion training. However, in this day of automation most pilots become monitors and go along for the ride and when the automation screws up it become more difficult to get their head back in the game. Remembering to turn off the system that’s giving the false info takes a back seat to the more prevalent......what’s it doing now question? Whether it is a runaway trim, sudden pusher activtion or pilot error as the most recent autopilot engagement incident with the altitude selector to zero, instructors are going to have a more difficult time churning out good qualified pilots!

(Duplicate Squawk Submitted)

Boeing Withheld Information on 737 Model From Pilots: Report

Boeing held back information about possible malfunctions with the new flight-control feature that’s believed to have played a role in the Lion Air jet crash that killed 189 people in Indonesia last month, The Wall Street Journal reports. FAA officials and safety experts involved in the investigation told the Journal that the automated stall-prevention system on the Boeing 737 MAX 8 and MAX 9 models can kick in and send a plane into a steep dive even if pilots are manually flying the aircraft. Investigators are still working to determine if that is what caused the Lion Air flight out of Jakarta to plunge into the Java Sea on Oct. 29.

https://www.yahoo.com/news/m/0e774373-d79f-33cd-b493-1d9f4e49bb01/boeing-withheld-information.html