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View Full Version : Lion Air 737 Max Accident


ShyGuy
10-28-2018, 06:47 PM
Still a developing story, Lion Air Boeing 737 MAX took off Jakarta and went missing shortly after. Presumed to have gone down. :(


Gammon89
10-28-2018, 06:52 PM
Can see flight track on flight radar24, took off climbed to 5000ft, ten minutes later last return showed3650 and speed increasing......

ShyGuy
10-28-2018, 06:54 PM
Looks like took off and accelerated right to 300 knots, I guess normal for that part of the world?

737 MAX 8 with CFM LEAP1 engines. PK-LQP


UALfoLIFE
10-28-2018, 07:02 PM
https://www.thesun.co.uk/news/worldnews/7605999/indonesian-plane-crash-lion-air-aircraft-crashed-take-off-jakarta/

Rip to those on board.

Wow brand new Max 8.

Sliceback
10-28-2018, 07:04 PM
‘Free speed’ or ‘no speed restriction’ is typically outside of the U.S.

deadstick35
10-28-2018, 07:14 PM
Nothing on the alt/gs plot looks stable.

ShyGuy
10-28-2018, 07:24 PM
Now reporting the pilot had asked for a return due to a problem. No other details. It does look like they were flying between 4700-5300 ft fluctuating dealing with whatever problem they faced.

UAL T38 Phlyer
10-28-2018, 07:55 PM
Does not sound good...crashed 13 minutes after takeoff. :(

https://www.bbc.com/news/world-asia-46014463

Baradium
10-28-2018, 08:40 PM
Now reporting the pilot had asked for a return due to a problem. No other details. It does look like they were flying between 4700-5300 ft fluctuating dealing with whatever problem they faced.

https://www.msn.com/en-us/news/world/indonesia-says-plane-crashes-in-java-sea-with-188-aboard-wreckage-found/ar-BBP2nb8?ocid=spartandhp&pfr=1


JAKARTA, Oct 29 (Reuters) - A Lion Air flight with at least 188 people on board is believed to have sunk after crashing into the sea off Indonesia's island of Java on Monday, shortly after take off from the capital on its way to the country's tin-mining hub, officials said.

A spokesman for Indonesia's search and rescue agency said the Lion Air flight, JT610, lost contact 13 minutes after takeoff, adding that a tug boat leaving the capital's port had seen the craft falling.
"It has been confirmed that it has crashed," the spokesman, Yusuf Latif, said by text message, when asked about the fate of the Lion Air plane, which air tracking service Flightradar 24 identified as a Boeing 737 MAX 8.
Debris thought to be from the plane, including aircraft seats, was found near an offshore refining facility, an official of state energy firm Pertamina said.Wreckage had been found near where the Lion Air plane lost contact with air traffic officials on the ground, said Muhmmad Syaugi, the head of the search and rescue agency.
"We don't know yet whether there are any survivors," Syaugi told a news conference. "We hope, we pray, but we cannot confirm."
Flight JT610 took off around 6.20 a.m. and was due to have landed in the capital of the Bangka-Belitung tin mining region at 7.20 a.m., the Flightradar 24 website showed.
"We cannot give any comment at this moment," Edward Sirait, chief executive of Lion Air Group, told Reuters, adding that a news conference was planned for later on Monday. "We are trying to collect all the information and data."
Preliminary flight tracking data from Flightradar24 shows the aircraft climbed to around 5,000 feet (1,524 m) before losing, and then regaining, height, before finally falling towards the sea.
It was last recorded at 3,650 feet (1,113 m) and its speed had risen to 345 knots, according to raw data captured by the respected tracking website, which could not immediately be confirmed.
Its last recorded position was about 15 km (9 miles) north of the Indonesian coastline, according to a Google Maps reference of the last coordinates reported by Flightradar24.
The accident is the first to be reported that involves the widely-sold Boeing 737 MAX, an updated, more fuel-efficient version of the manufacturer's workhorse single-aisle jet. The first Boeing 737 MAX jets were introduced into service in 2017.
Lion Air's Malaysian subsidiary, Malindo Air, received the very first global delivery.
Boeing is aware of the airplane accident reports and is "closely monitoring" the situation, it said on social network Twitter.
(Reporting by Augustinus Beo Da Costa and Ciny Silviana; Additional reporting by Jamie Freed in SINGAPORE and Tim Hepher in HONG KONG; Writing by Ed Davies; Editing by Clarence Fernandez)

Mesabah
10-28-2018, 10:47 PM
New aircraft delivered a few months ago, tracking data shows aircraft was climbing and descending through ~5000ft several times.

teamflyer
10-29-2018, 03:25 AM
RIP to all on board. Also curisous to what happened, a brand new 737 MAX built in 2018. Flt crew had more than 11k hours combined....

dera
10-29-2018, 03:32 AM
IAS and Alt disagree shown on previous flight.

dera
10-29-2018, 03:32 AM
RIP to all on board. Also curisous to what happened, a brand new 737 MAX built in 2018. Flt crew had more than 11k hours combined....

Previous flight had IAS and Alt disagree shown on takeoff. Not sure if related or not.

bright yellow
10-29-2018, 05:12 AM
*Ada info flight record* *penerbagan sebelumnya:*

A: PK LQP, B737 Max 8

D: 28.10.2018

O: Airspeed unreliable and alt disagree shown after take off. STS was also running to the wrong direction, suspected because of speed difference. Identified that CAPT instrument was unreliable and handover control to FO. Continue NNC of Airspeed Unreliable and ALT disagree. Decide to continue flying to CGK at FL280, landed safely rwy 25L

R: DPS CGK LNI 043

E: AFML

R: Capt William Martinus/133031, FO M Fulki Naufan/ 144291

BMEP100
10-29-2018, 05:38 AM
Wouldn't be the first time a plane departed with tape over the static ports, from the wash rack.

at6d
10-29-2018, 06:55 AM
An article I read this morning stated maintenance was performed twice just prior to this flight.

flensr
10-29-2018, 07:35 AM
Known pitch and power, very useful to know cold. At the very least if you're initially completely out of ideas, park the throttles 2/3 up, get the slats out for a little extra AOA margin, and put the waterline about 5 deg nose high to give you some time to sort out what's good and what's lying to you.

trip
10-29-2018, 08:10 AM
Previous flight had IAS and Alt disagree shown on takeoff. Not sure if related or not.

Daytime VMC apparently so hard to say yet.

Aero1900
10-29-2018, 08:27 AM
Known pitch and power, very useful to know cold. At the very least if you're initially completely out of ideas, park the throttles 2/3 up, get the slats out for a little extra AOA margin, and put the waterline about 5 deg nose high to give you some time to sort out what's good and what's lying to you.

Absolutely.
Obviously we don't know what happened yet, but it does seem that a lot of pilots from these parts of the world have so little background in flying, the fundamentals escape them. .... like the relief pilot of Air France. He had virtually zero experience flying anything other than a big, automated jet.

Know your rough pitch and power settings.

galaxy flyer
10-29-2018, 01:44 PM
Here’s Lion Air’s accident history since their founding in 2000:

Lion Air began flying in 2000. As of yesterday before the crash, they had 115 aircraft in their fleet.

Here is a list of their notable incidents. If we look through them, we can see that they have destroyed 8 aircraft in less than 20 years! The majority of their accidents are due to pilot error.

January 14, 2002
737-200 - 0 Fatalities - Aircraft Written Off
Takeoff accident due to incorrect flap configuration

November 30, 2004
MD82 - 25 Fatalities - Aircraft Destroyed
Landing runway excursion. Aircraft hydroplaned.

March 4, 2006
MD-82 - 0 Fatalities - Aircraft Written Off
Landing runway excursion. Left reverser was listed as INOP. Reverse thrust used on landing causing the aircraft to veer.

December 24, 2006
737-400 - 0 Fatalities - Aircraft Written Off
Landing accident. Incorrect flap setting and the aircraft was not aligned with the runway.

March 9, 2009
MD90 - 0 Fatalities - Aircraft Written Off
Landing runway excursion. The pilots continued with a non-stabilized approach. Only one reverser opened, causing the aircraft to pivot around the nose off of the runway.

November 2, 2010
737-400 - 0 Fatalities - Aircraft Written Off
Landing runway excursion. Non-stable approach, speed brakes not used until 42 seconds after touchdown.

April 13, 2013
737-800 - 0 Fatalities - Aircraft Destroyed
Landed short due to unstable approach.

August 6, 2013
737-800 - 0 Fatalities - Aircraft Damaged and Repaired
Landing excursion. Aircraft hit cows on the runway and veered off as a result of trying to avoid them.

February 1, 2014
737-900 - 0 Fatalities - Aircraft Damaged and Repaired
Hard landing resulting in tire damage and a tail strike. Four bounces before the impact.

February 20, 2016
737-900 - 0 Fatalities - Aircraft Not Damaged
Runway excursion. Late touchdown, delayed spoiler deployment, thrust levers not at idle position, and late of brake application. Aircraft came to a stop with the nose gear 1 metre past the end of the threshold.

April 29, 2018
737-800 - 0 Fatalities - Aircraft Damaged and Repaired
Runway excursion. Heavy rain was reported as they touched down and veered off to the left of the runway.

October 29, 2018
737-MAX8 - 189 Fatalities (Not confirmed) - Aircraft Destroyed
Aircraft crashed into water shortly after takeoff.

Make of that what you’ll will.

GF

sflpilot
10-29-2018, 05:11 PM
That’s not a good record. Although I don’t want to judge too much. I still remember seeing the fresh tire marks on the taxiway in ATL after DAL put a widebody down on it around 6:00 AM.

NaKaTaTuNa
10-30-2018, 04:14 AM
Known pitch and power, very useful to know cold. At the very least if you're initially completely out of ideas, park the throttles 2/3 up, get the slats out for a little extra AOA margin, and put the waterline about 5 deg nose high to give you some time to sort out what's good and what's lying to you.

I know the older 737s QRH has procedures for airspeed unreliable as a set of thrust settings in combination with a specific pitch attitude, as memory items.

Config flaps up: 4 degrees pitch up, and 75% N1
Config flaps extended: 10 degrees pitch up and 80% N1

Merely speculating but if airspeed unreliable came up again soon after take-off with flaps extended and memory item was selected, which would explain the sudden climb.

Fact that a Mayday wasn't immediately declared suggests that it was a known problem that they were trying to resolve - but what happened afterwards is anyone's guess?

RI830
10-30-2018, 09:02 AM
To support the pitch and power idea. I currently instruct on a corporate a/c at a local DFW facility.

On the cold and cruddy sim day.....I let the crew begin the climb to 10,000 at around 230-240 kts. Give the PF a blocked pitot probe and watch the reaction. I would say 80+ percent of the crews initial reaction is idle thrust and increase vertical rate. From there, about 20% get a shaker or get extremely close to it. The loss of airspeed averages 80 kts through this event. Very few people’s initial reaction is to seek a pitch and power setting till you can get things figured out.
Many cross compare air speeds and still allow the plane to fly them while the airspeed plummets.
It’s eye opening to see the thought process, reactions and ideas to different crews.

UAL T38 Phlyer
10-30-2018, 09:16 AM
Config flaps up: 4 degrees pitch up, and 75% N1
Config flaps extended: 10 degrees pitch up and 80%



This (similar numbers) became a memory item and a focus on CQ training at UA about 9 months ago...good stuff. Still ongoing.

But I was under the impression it was an FAA mandate, industry-wide. Obviously wouldn’t affect Lion Air....but I thought it might migrate from 121 to 135, or even Part 91 jet Ops.

Stimpy the Kat
10-30-2018, 09:38 AM
This just boggles my Mind: " I would say 80+ percent of the crews initial reaction is idle thrust and increase vertical rate. "

This is what a 727 crew did about 30+ years ago and was a much discussed item in many a recurrent class.

The mind boggling part is this...In what alternate universe does an aircraft ( ANY aircraft ) climb with thrust at Idle AND continue to accelerate no less ???

Hard to fathom the total lack of airmanship, situational awareness, and common sense.

Now...Put me in a Sim and watch me do the exact same thing as the 80% mentioned above.

DOH!

:)

aviatorhi
10-30-2018, 11:32 AM
Also had a FEEL DISAGREE message written up on the previous leg... those in combination would make for a very bad day (if the 737 is like the other Boeings I've flown more recently, it's been close to a decade since I've even sat in one).

e6bpilot
10-30-2018, 02:00 PM
Also had a FEEL DISAGREE message written up on the previous leg... those in combination would make for a very bad day (if the 737 is like the other Boeings I've flown more recently, it's been close to a decade since I've even sat in one).



The feel disagree is just a message telling you the pilot static systems are out of whack. It monitors the rudder feel system which in the grand scheme of things isn’t a huge deal at all.

Losing one or both pitot static systems in night or IMC, however, can be momentarily very disorienting. Depending on the level of automation and how dependent the pilots are on that automation, it can easily be deadly even in day VMC.

rickair7777
10-30-2018, 04:00 PM
This just boggles my Mind: " I would say 80+ percent of the crews initial reaction is idle thrust and increase vertical rate. "

This is what a 727 crew did about 30+ years ago and was a much discussed item in many a recurrent class.

The mind boggling part is this...In what alternate universe does an aircraft ( ANY aircraft ) climb with thrust at Idle AND continue to accelerate no less ???

Hard to fathom the total lack of airmanship, situational awareness, and common sense.

Now...Put me in a Sim and watch me do the exact same thing as the 80% mentioned above.

DOH!

:)

People are afraid to deviate from how they normally fly the plane, which is follow the FD and magenta line and stay out of the barber-pole.

My memory item #1 for unreliable AS or attitude is to fear for my life.

Once that's accomplished it then becomes easy to not worry about what ATC, FOQA, company or anybody else is going to think about what I'm doing. You need to fear death more than the barber-pole.

Also the attitude system on a modern jet generally KNOWS if it's jacked up and will give all kinds of warnings and flags. Absent that, start by trusting the AHRS. Pitot/Static might not even know that it's messed up.

FlyJSH
10-30-2018, 04:31 PM
August 6, 2013
737-800 - 0 Fatalities - Aircraft Damaged and Repaired
Landing excursion. Aircraft hit cows on the runway and veered off as a result of trying to avoid them.


GF

Cows on the runway? Maybe cut them a little slack on that one; kinda hard to drag the field in a 737.

ShyGuy
10-31-2018, 10:48 AM
I may be over generalizing here, but I think the average flight crew globally would fare poorly if they find themselves rolled beyond 90 degrees bank and beyond 40 degrees in the vertical. Eg, Adam Air, Air Asia, Colgan, etc.

The human instinct to pull back is just far too strong and shown repeatedly in all these accidents. In the case of Adam Air, once the dive established and they broke out of the clouds and saw the ground, they just yanked it back while still in a bank. Ripped the elevators/horizontal stabilizer right off the plane. Had the training and mindset been there to first level the wings and then slowly pull back, maybe they would have lived.

Hopefully the FAA mandated Upset Recover course in all 121 airlines for 2019 will help flight crews.

PNWFlyer
10-31-2018, 12:14 PM
Surprised not one person has mentioned the possibility that there could have been a bomb on board.

A passenger disturbance in the back could have been the reason they leveled off and requested a turn back to the airport. Then sets off a bomb.

kaputt
10-31-2018, 12:25 PM
Surprised not one person has mentioned the possibility that there could have been a bomb on board.

A passenger disturbance in the back could have been the reason they leveled off and requested a turn back to the airport. Then sets off a bomb.
Definitely not out of the realm of possibility. However a lot of times terror incidents like that end up being claimed by whatever group or individuals were responsible.

aviatorhi
10-31-2018, 01:14 PM
The feel disagree is just a message telling you the pilot static systems are out of whack. It monitors the rudder feel system which in the grand scheme of things isn’t a huge deal at all.

Losing one or both pitot static systems in night or IMC, however, can be momentarily very disorienting. Depending on the level of automation and how dependent the pilots are on that automation, it can easily be deadly even in day VMC.

Wait... what? Isn't the feel is run off the hydraulic system as part of the flight controls? I know it would take input from the pitot static as part of its operation, but in general the DISAGREE is referring to hydraulic pressure, is it not?

On some of the older jets you could make a very subtle input in the cockpit and have it translated into a significantly larger movement of the elevator.

dera
10-31-2018, 03:08 PM
Surprised not one person has mentioned the possibility that there could have been a bomb on board.

A passenger disturbance in the back could have been the reason they leveled off and requested a turn back to the airport. Then sets off a bomb.

Applying Occam's Razor, that's not very likely though.

Photoflier
11-02-2018, 04:37 PM
Reading now about the violent deviations on the previous flight due to what the crew described as a “flight control malfunction”. The crew elected to continue to destination after it rectified itself.

You’ve GOT to be kidding me....

rickair7777
11-05-2018, 12:40 PM
FDR shows airspeed indication problem.

https://www.npr.org/2018/11/05/664311109/indicator-malfunctioned-on-lion-air-jets-final-4-flights-black-box-data-show

UAL T38 Phlyer
11-05-2018, 01:55 PM
I would not be surprised if it is water in the lines (from tropical squalls while parked), a kink, a bad drain, or manufacturing debris in the lines (previously undiscovered because it was new), or a bad Air Data sensor.

Sadly, there are several examples in accident history of differing indications between Capt and FO...and the crew usually made the wrong determination.

FollowMe
11-05-2018, 02:00 PM
I would not be surprised if it is water in the lines (from tropical squalls while parked), a kink, a bad drain, or manufacturing debris in the lines (previously undiscovered because it was new), or a bad Air Data sensor.

Sadly, there are several examples in accident history of differing indications between Capt and FO...and the crew usually made the wrong determination.

Indeed, Birgenair 301 comes to mind. All he FO had to do was trust his cluster and push the nose down. Unfortunately CRM was not at an acceptable level and 189 people are no longer with us as a result.

Nutz
11-06-2018, 03:39 PM
I would not be surprised if it is water in the lines (from tropical squalls while parked), a kink, a bad drain, or manufacturing debris in the lines (previously undiscovered because it was new), or a bad Air Data sensor.

Sadly, there are several examples in accident history of differing indications between Capt and FO...and the crew usually made the wrong determination.


Except for all the times when it happened and they made the right decision that we never heard about.

FollowMe
11-06-2018, 04:11 PM
Except for all the times when it happened and they made the right decision that we never heard about.

It should NEVER happen. Period. If you haven’t looked at Berginair 301 you should, the CA had a bad airspeed that disagreed on t/o roll and elected to continue. At altitude they got slow but the CA airspeed said they were fast, he continued to pull back based on a bad airspeed even through the shaker and the FO saying I think we’re too slow. All that FO needed to do was push the nose down and 189 people would still be here. It is beyond unacceptable for a person to die because of poor CRM.

Accidents will happen, despite our amazing safety record recently aviation will always involve risk. But there is no excuse for CRM causing injury or death, it is entirely within our control.

Nutz
11-07-2018, 08:55 AM
It should NEVER happen. Period. If you haven’t looked at Berginair 301 you should, the CA had a bad airspeed that disagreed on t/o roll and elected to continue. At altitude they got slow but the CA airspeed said they were fast, he continued to pull back based on a bad airspeed even through the shaker and the FO saying I think we’re too slow. All that FO needed to do was push the nose down and 189 people would still be here. It is beyond unacceptable for a person to die because of poor CRM.

Accidents will happen, despite our amazing safety record recently aviation will always involve risk. But there is no excuse for CRM causing injury or death, it is entirely within our control.


Funny that you didn’t follow what I was saying despite your screen name.

FollowMe
11-07-2018, 03:26 PM
Funny that you didn’t follow what I was saying despite your screen name.

I followed just fine, thank you. Every day countless flights encounter nonstandard situations and great crews use CRM to mitigate, thus there is nothing for us to hear about.

My point is, it is a huge deal when an incident that could have been avoided with CRM costs lives. There is simply no excuse for it and every one of these instances should be broadcast as far and wide as possible until we eliminate them completely.

patplan
11-09-2018, 04:19 PM
Lion Air: Sensor replaced day before crash, problems persisted
Problems were reported on a Lion Air jet that crashed into the sea off Jakarta even after technicians replaced a sensor on board the aircraft, investigators said.

Indonesian authorities confirmed Wednesday that the angle of attack (AOA) sensor was replaced after a flight from Manado, in North Sulawesi to Denpasar, Bali on October 28. The Boeing 737 MAX 8 then made another flight to Jakarta that same day, and the pilots reported further problems....

...Investigators said the jet experienced problems on its last four flights -- including, crucially, the flight that crashed, according to Soerjanto Tjahjono, the head of the National Transportation Safety Committee (KNKT).

Boeing released an operational bulletin on Wednesday, warning all airlines about how to address any erroneous readings related to the AOA sensor. The Federal Aviation Administration (FAA) later issued its own directive that advised pilots about how to respond to similar problems....

In its statement on Wednesday, Boeing said that the Indonesian transport committee had indicated that Flight 610 had "experienced erroneous input from one of its AOA sensors." [source (https://www.seattletimes.com/business/boeing-aerospace/faa-follows-boeings-737-safety-alert-with-an-emergency-directive/)]
=======

My question is how long it takes normally to replace the said AOA sensor and to properly recalibrate it ?

It appears that PK-LQP had about 11-12 hours in DPS to have AOA sensor replaced before its next flight to CGK.

Thx.

rickair7777
11-10-2018, 07:24 AM
My question is how long it takes normally to replace the said AOA sensor and to properly recalibrate it ?

It appears that PK-LQP had about 11-12 hours in DPS to have AOA sensor replaced before its next flight to CGK.

Thx.

From my observations on other jets...

I would guess an hour tops (assuming the part and technician are both present). That's not pitot-static, so probably no involved calibration required (a pitot probe can take hours to test/calibrate after installation).

Unscrew some screws, disconnect cannon plug, installation is the reverse of that. Probably have to seal the plate, might take some time for the sealant to dry, possibly some number of hours.

Typhoonpilot
11-12-2018, 02:56 PM
The APA has put out a letter to all pilots to describe a system new to the Max that is not described in the Flight Crew Operating Manual. It is called Maneuvering Characteristics Augmentation System (MCAS) and will drive nose down stabilizer trim when the AoA exceeds a threshold based on airspeed and altitude. It only works in manual flight with flaps up.

1wife2airlines
11-12-2018, 04:56 PM
The APA has put out a letter to all pilots to describe a system new to the Max that is not described in the Flight Crew Operating Manual. It is called Maneuvering Characteristics Augmentation System (MCAS) and will drive nose down stabilizer trim when the AoA exceeds a threshold based on airspeed and altitude. It only works in manual flight with flaps up.

So, level flight autopilot on, but speed decays because of whatever, auto pilot trims stab up while pilots don't notice? When approaching stall, because of stab trim position, pilots don't have enough down elevator control to offset current stabilizer trim so Boeing trims down for them? Is this one of the things that Boeing added the MCAS for?
I also heard some reference to steep turns. If you trim during steep turns (my mantra learned during pilot training was "trim, trim, trim", but who knows now with the current aircraft) but let airspeed decay would the elevator not be able to unload the aircraft and Boeing wanted to help again.
Or is there some other reason for adding the MCAS other than the unlikely situation of the pilots trimming while slowing to that angle of attack that would trigger the MCAS. I could see something like that happening at altitude though but it could happen on earlier models also. Did the stretch change things where the stab might not allow elevator control? Of course, the older 737s ( I think) and the 727 could be put in a rare situation where you couldn't even trim electrically if you had opposite elevator input until you relaxed the elevator input and air load.

gipple
11-13-2018, 03:38 AM
Got to love how the FAA looks the other way and claims ignorance by allowing operators to put new aircraft into service with multiple changes and system enhancements. A 3 hour differences course (no mention of this system or even a paragraph in the AOM). No simulators produced prior to service introduction.
The bribery tentacles run deep into the polyester brigade.
Boeing and the airlines have the feds on their knees like a $10 hooker.

GuardPolice
11-13-2018, 04:08 AM
This is rapidly becoming a major scandal for Boeing.

https://www.wsj.com/articles/boeing-withheld-information-on-737-model-according-to-safety-experts-and-others-1542082575?mod=hp_lead_pos2

trip
11-13-2018, 07:40 AM
This is rapidly becoming a major scandal for Boeing.

https://www.wsj.com/articles/boeing-withheld-information-on-737-model-according-to-safety-experts-and-others-1542082575?mod=hp_lead_pos2

As it should be, I'm shocked that MAX pilots don't even know if they have a stick pusher or not? and if it can be overridden or not?

JetEagle
11-13-2018, 12:20 PM
Am I the only one who finds it odd that the 737 control yolk is missing a pitch trim disconnect button. Can someone who flies Boeing enlighten me as to the human factors philosophy in excluding a button that nearly every other airplane has on their controls.

Adlerdriver
11-13-2018, 12:45 PM
Am I the only one who finds it odd that the 737 control yolk is missing a pitch trim disconnect button. Can someone who flies Boeing enlighten me as to the human factors philosophy in excluding a button that nearly every other airplane has on their controls.
Hmmm :confused::confused: "Every other airplane"?

Don't remember such a control on the Airbus stick and you're correct, they're not on the Boeing yoke, nor are they called "trim disconnect". I think you might be referring to the stabilizer disconnect controls. They're not on the yoke....because they're not. I guess Boeing decided they had a better place to put them. Usually on the aft part of the throttle quadrant somewhere.

TiredSoul
11-13-2018, 01:09 PM
Am I the only one who finds it odd that the 737 control yolk is missing a pitch trim disconnect button. Can someone who flies Boeing enlighten me as to the human factors philosophy in excluding a button that nearly every other airplane has on their controls.

http://www.b737.org.uk/images/stabtrim_200.jpg

It’s a 200 but the 300/400 have it in the same place.

1wife2airlines
11-13-2018, 01:14 PM
http://www.b737.org.uk/images/stabtrim_200.jpg

It’s a 200 but the 300/400 have it in the same place.

When did Boeing decide not to put a mechanical stab trim brake in their 737 series.

Singlecoil
11-13-2018, 02:53 PM
So after doing some more reading on this, it appears this new system is a variation of the existing elevator feel system and the speed trim system. Essentially, it moves the stabilizer via the trim system and the trim wheels will rotate when this is occurring. The pilot should be able to stop the automatic movement of the stabilizer by using the thumb switches, and if that doesn't work, the cutout switches.
The system is slightly different, but the procedure for shutting it off is the same as it was on the NG.
It can drive the stabilizer in 10 second increments, which would be a decent amount of trim and stick force to overcome.
The pilots on the previous flight used the cutout switches to regain control and were successful.
Then you would have to pop out the handle and manually trim the airplane.

F4E Mx
11-13-2018, 04:15 PM
From the Emergency AD note (2018-23-51, Nov 7, 2018):

"This emergency AD was prompted by analysis performed by the manufacturer showing that if an erroneously high single angle of attack (AOA) sensor input is received by the flight control system, there is a potential for repeated nose-down trim commands of the horizontal stabilizer."

But the AOA sensor was changed prior to the accident flight. (?)

Adlerdriver
11-13-2018, 04:18 PM
When did Boeing decide not to put a mechanical stab trim brake in their 737 series.
So, you're saying at one time, 737 aircraft had a mechanical stab trim brake?

1wife2airlines
11-13-2018, 04:27 PM
So, you're saying at one time, 737 aircraft had a mechanical stab trim brake?

I was under that assumption, not having flown it, that the ability to stop the stabilizer from trimming by moving the elevator opposite it was the same mechanical system as is on the B727. Is it? If not was it an electrical system that Boeing then removed.

Adlerdriver
11-13-2018, 04:54 PM
I was under that assumption, not having flown it, that the ability to stop the stabilizer from trimming by moving the elevator opposite it was the same mechanical system as is on the B727. Is it? If not was it an electrical system that Boeing then removed.

I’m pretty sure that’s how I remember it working. Moving the control column in the opposite direction of undesired trim motion, automatically cuts out those trim inputs. Does that constitute a “mechanical brake” in your view?

757/767, 777 all have the same STAB cutout switches that remove hydraulic power from the stabilizer (never flown 747 or 787 but they look to be the same as well). Those are memory items switches if we receive warning of uncommanded/unscheduled stab movement. Once they're off, hydraulic power is removed from the stabilizer trim control module. I don't believe it's possible for the stab to move due to air loads (because of the actuator design).

jtriple7
11-13-2018, 08:45 PM
How much liability insurance do you think Boeing has?

What do think this crash will cost total? 300 mil, 1/2 Bil

cougar
11-13-2018, 09:09 PM
Does the 737 Max also have Elevator Feel Shift which increases aft stick force up to 4 times when a stall condition is sensed?

Typhoonpilot
11-14-2018, 03:47 AM
Airline industry rushes to understand nuances in 737 Max systems

13 November, 2018 SOURCE: Flight Dashboard BY: Jon Hemmerdinger Boston

Airlines, unions and regulators are working to understand the 737 Max's flight systems while unions uncover seeming errors in emergency "runaway stabiliser" checklists.

The work comes amid reports that the US industry was unaware Boeing had equipped the 737 Max with a new system that has been linked to the 29 October crash of a Lion Air 737 Max 8.

"We are working at an extraordinarily positive pace to share information," says a spokesperson for the Allied Pilots Association (APA), which represents pilots at American Airlines, a 737 Max operator.

"We are looking at differences between the Max and the non-Max aircraft" in an effort to understand nuances in stall prevention and notification systems, the union adds.

The issue apparently rests with the 737 Max's Manoeuvring Characteristics Augmentation System (MCAS), which is not on earlier-generation 737s. The technology automatically trims the aircraft's stabiliser, dropping the nose, to avoid stalls, according to American Airlines memo to pilots.

However, the system can also cause aircraft to dive if computers receive incorrect angle-of-attack data – a scenario called a "runaway stabiliser". Investigators have suggested faulty angle-of-attack information played a role in the Lion Air crash.

The APA says inclusion of the MCAS systems seems to have been accompanied by slight changes in how pilots should respond to runaway stabilisers.

Pilots have long been taught that pulling back on a 737's control column can arrest that condition – a fix pilots call a "breakaway", says the APA.

Indeed, American's runaway stabiliser checklist, dated 10 July, says, "stabiliser trim commands are interrupted when the control column is displaced in the opposite direction".

But the APA has now learned that the 737 Max is apparently different.

The APA cites a 7 November memo from American to pilots, in which the airline says that pulling the control column on a 737 Max will not arrest stabiliser movement if the dive was caused by faulty angle-of-attack data. "Control column force will not stop electric trimming", the memo says.

"On the 737NG, they had this breakaway system," says the APA. "On the Max, the company note says [that] pulling up on the stick doesn't work."

The union stresses that American's checklists also tell pilots to switch off the stabiliser system, which should fix the problem.

It adds that differences between 737 Max and 737NGs are not a problem – so long as pilots know about the changes.

The APA was not the only organisation caught unaware.

Also in the dark were American, Southwest Airlines, and, reportedly, Southwest's pilot association.

"We value our partnership with Boeing, but were unaware of some of the functionality of the Manoeuvring Characteristics Augmentation System (MCAS) installed on the Max 8," American tells FlightGlobal. "The work with the FAA and Boeing is ongoing, and we will continue to keep pilots informed of any updates."

"The MCAS was not mentioned in the manuals that Boeing provided to Southwest," Southwest says in a statement. "Therefore, MCAS is not mentioned in the Southwest Max 8 manuals."

The Dallas-based carrier's pilot union did not respond to requests for comment.

Boeing declines to comment about the MCAS, saying it is working to understand circumstances related to the Lion Air crash, which killed 189 people.

"We are taking every measure to fully understand all aspects of this incident, working closely with the investigating team and all regulatory authorities involved," it says. "We are confident in the safety of the 737 Max."

Following the crash, Boeing issued a service alert and the Federal Aviation Administration issued an emergency airworthiness directive requiring airlines to revise flight manuals to specify how pilots should response to runaway stabilisers.

American and Southwest have complied with the order, they say.

gipple
11-14-2018, 04:32 AM
So, you're saying at one time, 737 aircraft had a mechanical stab trim brake?

The -200 did. The knob was to hold the trash bag.

1wife2airlines
11-14-2018, 05:47 AM
The -200 did. The knob was to hold the trash bag.

That's what the 727 had. But it appears at some point Boeing replaced the mechanical trim brake with an electric system that also let opposite pitch input stop stab trimming, as in the Allied Pilots post above. So maybe Boeing took out that system in the Max. That would be a significant change. I remember the preflite first check of the day in the 727, trim one way and push the control column the other and see if the brake engaged. I guess that check is not done on current 737s.

1wife2airlines
11-15-2018, 08:26 AM
Gleaned off Pprune:

https://leehamnews.com/2018/11/14/boeings-automatic-trim-for-the-737-max-was-not-disclosed-to-the-pilots/

Adlerdriver
11-15-2018, 10:05 AM
Gleaned off Pprune:

https://leehamnews.com/2018/11/14/boeings-automatic-trim-for-the-737-max-was-not-disclosed-to-the-pilots/ Interesting. I wonder if they received any kind of EICAS (or whatever is in that a/c) caution/warning about anything flight control related during the event.

pickleford
11-16-2018, 07:30 PM
“In an interview Thursday, Capt. Todd Insler, chairman of the United branch of ALPA, the Air Line Pilots Association union, broke ranks with his counterparts at American Airlines and Southwest Airlines who earlier this week publicly complained that this wasn't disclosed to pilots during training or included in the 737 MAX pilot manuals.

Insler said many systems on an airplane work in the background without the pilot's knowledge. He compared it to watching television: "I don't need to know how it works."

“The story here is not why we didn't know about (the new system), it's why the pilots didn't fly the plane," said Insler.

That view drew a sharp rejoinder Friday from Capt. Dennis Tajer, chairman of the communications committee of the Allied Pilots Association (APA), representing American Airlines pilots.

Insler said one of his pilots flew test flights on the MAX and that all of United's pilots are very capable of hand flying the plane if automated systems fail.

"If the plane doesn't do what I want it to do, I make it do so. If it's not responding, I make it respond," Insler said vehemently. "There is plenty of feedback as to how this airplane flies, more than enough inputs and opportunity to recover."

He dismissed as "speculation" the heavy discussion in the media -- largely based on a safety-warning bulletin sent out to all airlines by Boeing and a follow-on airworthiness directive by the FAA -- as to whether the MCAS system is implicated in the Lion Air accident. He said people should wait for the investigation to come up with a definitive account of what caused the crash.
Insler's suggestion that Boeing didn't necessarily have to provide pilots information specifically about MCAS supports the manufacturer's stated argument, as cited to Southwest pilots last weekend.”

rickair7777
11-16-2018, 07:56 PM
I beg to differ... I need to know about any potential control surface actuation, when hand-flying or not.

F4E Mx
11-17-2018, 04:08 AM
The good captain above seems to forget the accident aircraft on previous flights had a split between the pilot and copilot sides on indicated air speed and the altimeter readings. I guess he could overcome those discrepancies also on a tight approach to minimums on a short runway?

It may be that perfectly good AOA, IAS, and ALT readings are going into the Central Air Data Computer (or whatever Boeing calls it) and corrupted data are coming out.

rideforever
11-19-2018, 05:09 AM
If the plane doesn't do what I want it to do, I make it do so. If it's not responding, I make it respond," Insler said vehemently. "There is plenty of feedback as to how this airplane flies, more than enough inputs and opportunity to recover.

I would be very happy if Insler was flying my plane, he has taken responsibility in his life. But how many pilots today are just xbox players ? Isn't that the goal of the manufacturers to cheaper pilot costs and training and so on. They are not really encouraged to know what is going on, it's all a game. In this case a pilot might have said : "well if I wish to completely disable computation then I must also disabled STS". Which would have also disabled the new undocumented system .... working on first principles. But pilots just follow the training with no independent thoughts. Independent thought is expensive to train.

Anyway I think it is somewhat beyond this society to change course on its automation cheapening staff fanaticism, and so we need to be practical. Giving pilots access to all the AoA indicators onthe aircraft, their raw data (there are 4 I believe on the 737, 2 are on the wings) ... that would be good. And then having the concept of disabling all the computational inputs and knowing how to do that in 3 seconds flat ... which I am sure will arrive giving this accident. Also having a 3rd AoA tube outside would be good; if you have 2 and 1 fails ... that's not so much helpful when on instruments !
These 2 measures are cheap and idiot proof solutions.

btw are there any other control systems on 737 that need disabling ? Anything else ? Because pilots seem to only disabled the autopilot and navigation in the first instance.

rickair7777
11-19-2018, 06:22 AM
I would be very happy if Insler was flying my plane, he has taken responsibility in his life. But how many pilots today are just xbox players ? Isn't that the goal of the manufacturers to cheaper pilot costs and training and so on. They are not really encouraged to know what is going on, it's all a game. In this case a pilot might have said : "well if I wish to completely disable computation then I must also disabled STS". Which would have also disabled the new undocumented system .... working on first principles. But pilots just follow the training with no independent thoughts. Independent thought is expensive to train.

Anyway I think it is somewhat beyond this society to change course on its automation cheapening staff fanaticism, and so we need to be practical. Giving pilots access to all the AoA indicators onthe aircraft, their raw data (there are 4 I believe on the 737, 2 are on the wings) ... that would be good. And then having the concept of disabling all the computational inputs and knowing how to do that in 3 seconds flat ... which I am sure will arrive giving this accident. Also having a 3rd AoA tube outside would be good; if you have 2 and 1 fails ... that's not so much helpful when on instruments !
These 2 measures are cheap and idiot proof solutions.

btw are there any other control systems on 737 that need disabling ? Anything else ? Because pilots seem to only disabled the autopilot and navigation in the first instance.

Careful folks, possible lawyer on a fishing expedition.

Adlerdriver
11-19-2018, 06:50 AM
Careful folks, possible lawyer on a fishing expedition.Glad you got something out of that. It’s probably me, but I really had a hard time figuring what he’s trying to tell us.

FlyJSH
11-20-2018, 07:22 PM
Anyway I think it is somewhat beyond this society to change course on its automation cheapening staff fanaticism, and so we need to be practical. Giving pilots access to all the AoA indicators onthe aircraft, their raw data (there are 4 I believe on the 737, 2 are on the wings) ... that would be good. And then having the concept of disabling all the computational inputs and knowing how to do that in 3 seconds flat ... which I am sure will arrive giving this accident. Also having a 3rd AoA tube outside would be good; if you have 2 and 1 fails ... that's not so much helpful when on instruments !
These 2 measures are cheap and idiot proof solutions.

btw are there any other control systems on 737 that need disabling ? Anything else ? Because pilots seem to only disabled the autopilot and navigation in the first instance.

Yes, yes there are other systems that need disabling.

First is the retractable landing gear. Yes, it saves fuel, increases speed, and lowers ticket prices; but at what cost??? There is a one in a ga-zillion chance it could not extend, cause the plane to flip over, burst into flames, and make me lose my laptop during the emergency egress.

Next, I would eliminate all AOA detection and reporting devices; they can be WRONG! I don't want anything that could feed me bad information! For that matter, air speed indicators, altimeters, and VSIs can fail too! Let's get rid of them.

And as for engines.....don't even get me started! :):rolleyes:;)

rideforever
11-21-2018, 05:15 AM
What else needs disabling ... in an emergency when you need to isolate the computer ?

It seems that these pilots should have disabled the STS in any case if they had wished to isolate computer direction control surfaces ... but they didn't. Anything else ?

Probably the pilots were trying to make jokes as well : which is fine, as long as you know the answer when you need it.

tomgoodman
11-21-2018, 05:39 AM
Careful folks, possible lawyer on a fishing expedition.

Probably so. A trout fisherman would have written a better post. :p

UAL T38 Phlyer
11-21-2018, 07:15 AM
Probably so. A trout fisherman would have written a better post. :p
***********
:rolleyes:

Excargodog
11-21-2018, 08:36 AM
Got to love how the FAA looks the other way and claims ignorance by allowing operators to put new aircraft into service with multiple changes and system enhancements. A 3 hour differences course (no mention of this system or even a paragraph in the AOM). No simulators produced prior to service introduction.
The bribery tentacles run deep into the polyester brigade.
Boeing and the airlines have the feds on their knees like a $10 hooker.

I think it is deeper than this. For a LOT of federal agencies (FAA AND FDA come to mind), the technical skills of the agency personnel are markedly inferior to those producing the product and the agency DELEGATES a great deal of approval authority to employees of the organization much like they do with DPEs. And they do that despite the conflict of interest because the agency doesn't have, can't get, and could never hope to retain individuals with those skills. Not in the civil service system anyway.

ptarmigan
11-21-2018, 04:06 PM
Here are a couple of articles I have written on this, the second one in particular raises critical aspects:

https://airlinesafety.blog/2018/11/19/what-we-can-learn-from-lion-air-610-thoughts-on-lion-air-reprinted-from-curt-lewis-flight-safety-information-news/

https://airlinesafety.blog/2018/11/19/the-aoa-problem-what-we-can-do-about-it/

rickair7777
11-21-2018, 07:04 PM
I think it is deeper than this. For a LOT of federal agencies (FAA AND FDA come to mind), the technical skills of the agency personnel are markedly inferior to those producing the product and the agency DELEGATES a great deal of approval authority to employees of the organization much like they do with DPEs. And they do that despite the conflict of interest because the agency doesn't have, can't get, and could never hope to retain individuals with those skills. Not in the civil service system anyway.

All true.

Some government functions do require bleeding edge, and innovative work-arounds like DARPA can be devised (they developed both GPS and the internet). But in the case of FAA oversight the challenge for the government is to not to be the bleeding edge, but rather to simply not get snowed.

It can be done. Professional detectives are not typically mensa material, but experience and professionalism allow them to catch many criminals who may be quite intelligent and talented.

JamesNoBrakes
11-21-2018, 08:54 PM
I think it is deeper than this. For a LOT of federal agencies (FAA AND FDA come to mind), the technical skills of the agency personnel are markedly inferior to those producing the product and the agency DELEGATES a great deal of approval authority to employees of the organization much like they do with DPEs. And they do that despite the conflict of interest because the agency doesn't have, can't get, and could never hope to retain individuals with those skills. Not in the civil service system anyway.

Also, the big push from Congress these days is to "back away" from regulation and intensive oversight. Rely on "safety systems" that are less personnel and resource-intensive. Not just from a cost/personnel issue, but to "cut the red tape" for the manufacturers.

PlaneS
11-22-2018, 10:46 AM
Probably so. A trout fisherman would have written a better post. :p

As a non-binary gender fluid vegan trout fisherman I take serious offense to this post

patplan
11-23-2018, 02:02 PM
Some excerpts from Indonesian NTSC's exposition to the parliament...Here they presented some relevant data they'd extracted from the FDR on the plane's last flight and on its penultimate one.



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http://i.piccy.info/i9/f2d217f2acc4fd83123f933bec8f3634/1542986401/132644/1270057/lionair_b38m_pk_lqp_jakarta_181029_knkt_data_Page_ 07.jpg
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http://i.piccy.info/i9/a36f8e02e46b82a4ae8c440726e0473b/1542986436/173182/1270057/lionair_b38m_pk_lqp_jakarta_181029_knkt_data_Page_ 08.jpg
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http://i.piccy.info/i9/4f9940a8e5e27efb702e89908d201839/1542986462/133407/1270057/lionair_b38m_pk_lqp_jakarta_181029_knkt_data_Page_ 09.jpg
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source:
- http://avherald.com/files/lionair_b38m_pk-lqp_jakarta_181029_knkt_data.pdf

Adlerdriver
11-23-2018, 06:49 PM
If you can actually read those graphs on your screen and know what they’re telling us (plus define penultimate :rolleyes:)..... maybe you could just give us the readers digest version if there’s some kind of relevant info to help explain events leading to the crash.

patplan
11-23-2018, 08:34 PM
If you can actually read those graphs on your screen and know what they’re telling us (plus define penultimate :rolleyes:)..... maybe you could just give us the readers digest version if there’s some kind of relevant info to help explain events leading to the crash.

Comparatively speaking, the "penultimate" flight ;) had the MCAS [color: purple] being shut off. The left stick shaker was ON the whole time. The CAPT & FO AOA sensors disagreed by about 20 Deg. They managed to stay at around FL260-FL280 for the entire flight before landing safely at CGK.

For the "ultimate" flight ;) , the situation was almost similar. The CAPT & FO AOA also had the 20 Deg discrepancy. The stick shaker was on immediately after the take off. However, MCAS [color: purple] went into action immediately after FLAP 0, then it stopped when the plane had gone to FLAP 5 [??] , but MCAS went ballistic again when the plane was back at FLAP 0. PF countered MCAS by manual trim up throughout. The plane managed to stay at FL50 give and take but with the speed of 300+knts[??]. Stabilizer ran close to zero. The plane hit the speed in the excess of 400knts before it crashed to the sea.


For clearer pictures...
- http://i.piccy.info/i9/f2d217f2acc4fd83123f933bec8f3634/1542986401/132644/1270057/lionair_b38m_pk_lqp_jakarta_181029_knkt_data_Page_ 07.jpg

- http://i.piccy.info/i9/4f9940a8e5e27efb702e89908d201839/1542986462/133407/1270057/lionair_b38m_pk_lqp_jakarta_181029_knkt_data_Page_ 09.jpg

314159
11-24-2018, 08:44 PM
Here's what it looks like to me:

From takeoff, the Right AoA sensor consistently reported about 20 degrees higher than the Left AoA sensor. The stick shaker went off almost the entire flight, and the MCAS system was applying periodic nose down trim and the pilots were periodically reacting by applying nose up trim. They're able to maintain a fairly stable situation until what looks like the last little bit. For whatever reason, at the end, there are fewer manual nose up trim inputs, and more automated nose down trim inputs, and the stabilizer eventually reaches full nose-down trim. At the end, it appears that right side pilot is pulling back on the yoke hard and there are fewer trim inputs. The stab trim is going to win over the elevator, and at the end it does.

Total supposition: It's possible they switched flying pilots and the right seat pilot focused more on elevator pressure and didn't apply trim as much as the left seat pilot had, which means that the near-stable situation the left-seat pilot had maintained was lost.

FollowMe
11-25-2018, 05:37 AM
Here's what it looks like to me:

From takeoff, the Right AoA sensor consistently reported about 20 degrees higher than the Left AoA sensor. The stick shaker went off almost the entire flight, and the MCAS system was applying periodic nose down trim and the pilots were periodically reacting by applying nose up trim. They're able to maintain a fairly stable situation until what looks like the last little bit. For whatever reason, at the end, there are fewer manual nose up trim inputs, and more automated nose down trim inputs, and the stabilizer eventually reaches full nose-down trim. At the end, it appears that right side pilot is pulling back on the yoke hard and there are fewer trim inputs. The stab trim is going to win over the elevator, and at the end it does.

Total supposition: It's possible they switched flying pilots and the right seat pilot focused more on elevator pressure and didn't apply trim as much as the left seat pilot had, which means that the near-stable situation the left-seat pilot had maintained was lost.

Highlighting the drastic change by Boeing in that neither opposite trim nor yoke pressure will cease the flight computer trim input. That is a huge factor in this accident and one I’m sure Boeing is already formulating a plan to correct.

Adlerdriver
11-25-2018, 07:06 AM
Is the solution going to be turning off the stab cutout switches?
That's the burning question in my mind. Would that have solved this issue (switches off, don't exceed current airspeed), or is it a deeper problem?

dera
11-25-2018, 09:49 AM
The stab trim is going to win over the elevator, and at the end it does.



The other way round, elevator will always overpower the trim. That's a Part 25 requirement.

pangolin
11-25-2018, 11:46 AM
The other way round, elevator will always overpower the trim. That's a Part 25 requirement.

It’s a stab.

dera
11-25-2018, 01:22 PM
It’s a stab.

That doesn't matter. Moving stabilizers have the same requirements for control forces as trim surfaces.

25.255, 25.655 and I think 25.161, and AC25-7B (or whatever the current revision was today).

ShyGuy
11-25-2018, 04:10 PM
I still think they need to find the CVR to find out what really happened from a human perspective.

F4E Mx
11-25-2018, 04:18 PM
FAA part 25 is readily available in PDF format on the FAA.gov website as is the Advisor Circular AC25-7D (the current issue). I could not find anywhere where the pilots' elevator force is required to overcome full nose down or full nose up trimmable stabilizer force.

The Advisory Circulator did say that with the aircraft stabilizer set at the maximum nose down or nose up position that would not trigger a configuration warning the aircraft should be flyable at the forward and aft CG limits.

The question is then what is the difference between full stabilizer travel and travel required to illuminate the configuration light.

dera
11-25-2018, 05:07 PM
The Advisory Circulator did say that with the aircraft stabilizer set at the maximum nose down or nose up position that would not trigger a configuration warning the aircraft should be flyable at the forward and aft CG limits.

The question is then what is the difference between full stabilizer travel and travel required to illuminate the configuration light.

That's just for takeoff. I'm thinking 25.671(c)
.
"to be capable of continued safe flight and landing after any of the following failures or jamming in the flight control system and surfaces (including trim, lift, drag, and feel systems)"

(c)(1)

"(1) Any single failure, excluding jamming (for example, disconnection or failure of mechanical elements, or structural failure of hydraulic components, such as actuators, control spool housing, and valves)."

Also 25.671(c)(3)
"A runaway of a flight control to an adverse position and jam must be accounted for if such runaway and subsequent jamming is not extremely improbable."

Extremely improbable is defined in 25.1309. "they are not anticipated to occur during the entire operational life of all airplanes of one type".

So - airplane must be controllable if a control surface can runaway to a mechanical stop.

Boeing is in a world of hurt if the MCAS is shown to be Part 25 uncompliant.

symbian simian
11-25-2018, 05:15 PM
That's just for takeoff. I'm thinking 25.671(c)
.
"to be capable of continued safe flight and landing after any of the following failures or jamming in the flight control system and surfaces (including trim, lift, drag, and feel systems)"

(c)(1)

"(1) Any single failure, excluding jamming (for example, disconnection or failure of mechanical elements, or structural failure of hydraulic components, such as actuators, control spool housing, and valves)."

Also 25.671(c)(3)
"A runaway of a flight control to an adverse position and jam must be accounted for if such runaway and subsequent jamming is not extremely improbable."

Extremely improbable is defined in 25.1309. "they are not anticipated to occur during the entire operational life of all airplanes of one type".

So - airplane must be controllable if a control surface can runaway to a mechanical stop.

Boeing is in a world of hurt if the MCAS is shown to be Part 25 uncompliant.

Boeing has been in that world of hurt for a while. It is in the manual that to recover from a stall you need to apply AND trim and reduce power as the elevator doesn't have enough authority.

dera
11-25-2018, 05:22 PM
Boeing has been in that world of hurt for a while. It is in the manual that to recover from a stall you need to apply AND trim and reduce power as the elevator doesn't have enough authority.

That's a violation of pretty basic Part 25 stuff. The lawsuits will be interesting!

F4E Mx
11-25-2018, 05:39 PM
"A runaway of a flight control to an adverse position and jam must be accounted for if such runaway and subsequent jamming is not extremely improbable."

So basically we do not know if the 737 was designed to be controllable in the instance of full runaway stabilizer travel or not. The instance of the crash might suggest not.

dera
11-25-2018, 05:44 PM
"A runaway of a flight control to an adverse position and jam must be accounted for if such runaway and subsequent jamming is not extremely improbable."

So basically we do not know if the 737 was designed to be controllable in the instance of full runaway stabilizer travel or not. The instance of the crash might suggest not.

Extremely improbable means that it is never expected to happen to the whole fleet, ever.
If a simple AOA sensor failure makes it happen and there's no compensation method for it, this will be nasty, NASTY, for Boeing.
I would say this failure mechanism is "probable" according to the guidance in 25.1309.

314159
11-25-2018, 06:34 PM
That doesn't matter. Moving stabilizers have the same requirements for control forces as trim surfaces.

25.255, 25.655 and I think 25.161, and AC25-7B (or whatever the current revision was today).

I don't think you're reading that correctly. The maximum out-of-trim condition that must be correctable with the elevator is that resulting from 3 seconds of trim operation. This is *way* beyond 3 seconds.

The stab wins, it always does. I don't know of any modern jet where the elevator can overcome the stab in worst case scenarios. This should be pretty well covered in groundschool...

If the elevator always won, we wouldn't need the cutout switches.

dera
11-25-2018, 06:43 PM
I don't think you're reading that correctly. The maximum out-of-trim condition that must be correctable with the elevator is that resulting from 3 seconds of trim operation. This is *way* beyond 3 seconds.

The stab wins, it always does. I don't know of any modern jet where the elevator can overcome the stab in worst case scenarios. This should be pretty well covered in groundschool...

If the elevator always won, we wouldn't need the cutout switches.

25.671

""A runaway of a flight control to an adverse position and jam must be accounted for if such runaway and subsequent jamming is not extremely improbable"

TiredSoul
11-26-2018, 02:20 AM
I still think they need to find the CVR to find out what really happened from a human perspective.

I’m going to take a stab at it and say this crew didn’t fully understand what was going on systems wise.
Previous crews did...or got lucky.

rickair7777
11-26-2018, 06:39 AM
I’m going to take a stab at it and say this crew didn’t fully understand what was going on systems wise.
Previous crews did...or got lucky.

Either way, boeing should not have put them in that position.

ShyGuy
11-27-2018, 09:51 PM
Looks like a constant 11 minute struggle with control yoke only trying to fight the automated nose down input from MCAS.


https://www.nytimes.com/2018/11/27/world/asia/indonesia-lion-air-crash-.html


It would seem the previous crew used the switches on the center pedestal to remove electrical power to the stabilizer and regained control manually. Unfortunately it seems this crew did not do this. The entire time, that trim wheel would have been spinning and spinning. It's sad they weren't able to just remove power to it.

Still hope they recover the CVR. Only that will show the human interaction, what they said, potentially what they thought, etc.

F4E Mx
11-28-2018, 03:49 AM
It would seem there could be several reasons for a runaway stabilizer besides the failure of the AOA input. Isn't this covered in the simulator lessons? And what happens if the pedestal switch doesn't work? There is no clear evidence they DIDN'T try to actuate it. Is the circuit breaker marked to be able to positively disable the system?

WideRide
11-28-2018, 04:22 AM
I don't think you're reading that correctly. The maximum out-of-trim condition that must be correctable with the elevator is that resulting from 3 seconds of trim operation. This is *way* beyond 3 seconds.

The stab wins, it always does. I don't know of any modern jet where the elevator can overcome the stab in worst case scenarios. This should be pretty well covered in groundschool...

If the elevator always won, we wouldn't need the cutout switches.

Not true...the B757 and B767 has adequate control authority such that the plane can be flown with the elevator inputs regardless of stab trim setting...including full nose up or nose down. It's not pretty and it's no fun, and it can take two pilots on the yoke as your arms get tired, but it can be done. I've done it in the simulator multiple times.

I was trained in both jammed stab full nose up and nose down-trimmed landings as well at my carrier.

I haven't flown a 737 since the -200 so I don't know anything about the MAX and its MCAS system.

sgrd0q
11-29-2018, 04:59 AM
Boeing has a problem with the elevator. The elevator needs to be able to overpower the stab even if the stab is jammed full nose up or full nose down.

They need to redesign the elevator and the FAA needs to enforce their own rules and regulations.

The elevator not being able to overpower the stab is BS. Having to trim to recover from a stall as the elevator doesn't have enough authority is BS. Boeing knows it and tried to "fix" it by adding the MCAS to drive nose down stabilizer trim automatically based on the AOA. Oh, and to make sure it is effective they designed it so that the stabilizer trim commands are NOT interrupted even when the control column is displaced in the opposite direction. Oh, and they didn't bother to tell anyone. What can go wrong? This is total BS.

You can do more training to switch off electrical power to the stab, but that is not a complete solution. What happens if the stab jams fully deflected next time?

Interestingly, it looks like you can overwrite the automatic movement of the stabilizer by using the thumb switches (sadly no more by pulling up) so it looks like the MCAS trimmed the nose down, the pilot flying pulled up and trimmed up, effectively keeping the situation nearly stable. Looks like this repeated multiple times, but at the end they stopped trimming and ended up just pulling up which ultimately resulted in the loss of control.

F4E Mx
11-30-2018, 03:56 AM
"...but at the end they stopped trimming and ended up just pulling up which ultimately resulted in the loss of control."

They stopped trimming because they ran out of trim? Seriously apologize if this is a dumb question.

NaKaTaTuNa
11-30-2018, 11:17 AM
"...but at the end they stopped trimming and ended up just pulling up which ultimately resulted in the loss of control."

They stopped trimming because they ran out of trim? Seriously apologize if this is a dumb question.

Where is the discussion around flaps in all of this? The theory around MCAS and pilot not understanding it and trying to counter it to no avail through trim is well rehearsed. If you look at the data the pilots had issues from the start but appeared to have gained some momentary control and altitude. Goes back to my theory that pilots probably responded properly to the initial airspeed and altitude disagree and as per MI adjusted flaps but when this was then further compounded by more issues perhaps had neglected or forgot to retract flaps? Between flaps and trim which would win?

andreas500
01-13-2019, 07:16 PM
https://www.channelnewsasia.com/news/asia/lion-air-indonesia-finds-cockpit-voice-recorder-of-crashed-jet-11119706

JAKARTA: Indonesia has found the cockpit voice recorder from a Lion Air plane more than two months after the Boeing Co 737 MAX jet crashed into the sea near Jakarta, killing all 189 on board, an official said on Monday.

"It's been found, but we have not received information of the location yet," Haryo Satmiko, deputy chief of Indonesia's transport safety committee (KNKT), said by text message.

Read more at https://www.channelnewsasia.com/news/asia/lion-air-indonesia-finds-cockpit-voice-recorder-of-crashed-jet-11119706



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