Back to Squawk list
  • 93

U.S. pilots flying 737 MAX weren’t told about new automatic systems change linked to Lion Air crash

Pilots for two U.S. airlines flying Boeing's 737 MAX weren't trained about a key change to an automatic system that's been linked to the fatal crash of a Lion Air jet last month, according to pilot representatives at both airlines. ( More...

Sort type: [Top] [Newest]

Jeff Lawson 8

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.
selenio 6
Hardware, Pilots training and manuals
not aligned. It seem unbeliveable.
ADXbear 14
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..
bartmiller 2
We live in an age of fly-by-wire. Control sticks and yokes are no more of a flight control than the mouse on your computer.

There is no such thing as "hand flying" any more. The question is where the software and hardware engineers separated out functionality cleanly enough that pieces (like the angle of attack sensing) can be separately and reliably disabled.

This is more expensive in design, coding and testing.
You said it brother. This one is going to be very interesting to follow I think.

[This comment has been downvoted. Show anyway.]

Dubslow 11
Chesley_Sullenberger, for example, specifically said that the Airbus computers prevented him from properly flaring the ditching of US1549. Surely, if it was possible to truly hand fly the aircraft, that would have been the time to do it.
back at it again....and to whom are you addressing as nonpilots! "it's part of learning about them" that is not aviation language! your statement adds o to this blog. Just for the record why don't you enlighten us to your vast experience in AVIATION....
joel wiley 2
Are you trying for the Wilbur Sanchez FA for Pilots only award?
wingbolt 1
Those were the good ole days!
wingbolt 2
Waiting for a post from Wilbur was like waiting for a Little Orphan Annie decoder ring to come in the mail. Then after you read it you sort of had the Ovaltine trick feeling.
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.
Correction (NOT explained in detail)
David Loh 6
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.
David Loh 3
Boeing said. “We are confident in the safety of the 737 MAX. Safety remains our top priority.”
That's comforting!
alex hidveghy 1
Isn’t that what all airlines say - including the Lion COO??
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.
David Beattie 3
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.
jthyland 3
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.
F.O. Krupke 5
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?
kyle estep 5
The stall protection system is designed to prevent a full stall. First you should get a shaking of the yoke and disconnecting of the autopilot, if you still don't do anything and continue further into a problematic angle of attack (stall) then there is a system on transport category aircraft that forces the yoke forward (I can't speak to what Airbus planes do with their sidestick). There is a way to deactivate this system if it malfunctions...… if you have time, awareness, and altitude to do it.
Cal Orr 2
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.
Jim DeTour 2
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.
Highflyer1950 2
I agree with btweston, aircraft was too low, too slow and the crew did not anticipate the long spool up time required for the engines from idle to Go Around thrust. Normal flight law allows for best lift over drag but with engines at idle, the aircraft just gently sinks!! Funny, that was one of the first things taught about hi by-pass turbo fans.
btweston 2
No, that plane simply fell behind the power curve. The thrust levers were not inhibited, they were just too low and too slow with too much drag to accelerate and climb before hitting the trees. And the AOA protection was working properly as well. Had the pilot been able to pull the nose up any more the plane would have stalled and killed more people.
The plane nose dived into the Java Sea (not the trees) and killed everyone on board.
I see a giant Lawsuit coming sell your Boeing stock now !
lecompte2 1
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.
David Beattie 1
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.
lecompte2 1
Boeing's has no excuse for this poor design that caused this crash or the fact they kept this secret apparently even in the certification process. This does not excuse the airline for not training their pilots for a situation they didn't know about.
lecompte2 1
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
Mike Williams 1
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.
Bryan Jensen 1
For a system change that critical not to be shared with the pilots is unacceptable to GROSSLY understate it.
C Anderson 1
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?
mikeap 1
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.
john kilcher 1
Oh, gawd!!
sharon bias 1
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.
linbb -4
In health care it usually CYA afterward and patient is dead and the doctor just pays the survivors.
joel wiley 3
In health care, it's the doc's insurer who pays, than raises his/her rates which in turn ...
The analogy between industries breaks down quickly. Doctors don't kill their clients in job lots, nor do they follow/lead their clients down under the daisies.
paul trubits 5
Healthcare has taken the spirit of aviation to reduce errors. Checklists are now routine and have prevented many errors. No one wants to make mistakes especially when the stakes are so high. It appears that Boeing set up these pilots to fail.
john kilcher 4
A bit of a harsh statement, but surely, Boeing are culpable. Also, I find suspect, is perhaps a pilot shortage and the newer pilots coming in, (even though the two here had hours in the MAX0, are too accustomed to automation with very little stick time on the a/c.
Clarke Ramsey 1
I Total tottaly agree
bartmiller 2
Yes, but it is the same computers controlling the same actuators. The computer is always a part of the flight control system. Turning off the autopilot is just really turning off some software features.
stratofan 0
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!
racerxx 6
If I am understanding this correctly, this safety feature engages during a manual, no flaps setting. If the reading being fed to the computer were off, they would have been fighting a losing battle as the aircraft thought it was stalling and would override the pilot's actions. I'm certain there is a way to disable this as well, but not knowing so would have been the problem.
hornet135 3
Sounds like you didn't read the article.
Bryan Morgan 0
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?
Highflyer1950 -9
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!
Dubslow 6
Did you not read the article? Actual line pilots specifically said this wasn't in the conversion training.
Highflyer1950 3
Yes Bill, I read the article. Instead of a pusher system the Max utilizes an auto down stab trim as an action to an impending stall. There is however, as far as I can detect, a memory item action for a runaway trim! If this is such a killer item then yes, it would have been covered but as true to form most foreign pilots (and some local) do not bother listen and learn let alone understand the system itself. The 737 is pretty much the easiest aircraft in the world to fly, it has to be so every country can fly them without peril! Lately , the engineers have been getting way too involved in making all the systems fully automatic until they fail! Bigger engines, well lets’ lengthen the nose strut 8” to give more ground clearance? Now at flap 30/40 the flight spoilers will raise slightly to reduce lift, which then adds power resulting in a higher angle of attack, higher nose attitude so you don’t land on the nose wheel!! However, I could be wrong.
David Beattie 2
Good info. Seems they are trying to Airbus-ize the 737 to make it pilot proof. What could go wrong!?
wingbolt 2
I have a feeling there is a Boeing version and these pilot’s version and most likely the truth is somewhere in the middle.
David Loh 1
If it is or is Not in the Manual it can be easily proven. No such crap as Boeing or pilot version. If it is in the manual and is not mentioned at all in conversion training I'm sure some pilot among all the hundreds alreadt converted would have spotted it.
wingbolt 0
The best way to find out if it’s in the Flight Manual would be to ask a MAX pilot, not Boeing or the pilot’s union. It already appears the union has been putting out jaded information.
(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.


Don't have an account? Register now (free) for customized features, flight alerts, and more!
This website uses cookies. By using and further navigating this website, you accept this.
Did you know that FlightAware flight tracking is supported by advertising?
You can help us keep FlightAware free by allowing ads from We work hard to keep our advertising relevant and unobtrusive to create a great experience. It's quick and easy to whitelist ads on FlightAware or please consider our premium accounts.