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Another 737 MAX down.

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On a modern swept wing commercial airliner, the AOA indication is also a good reference for efficiency. A higher than normal AOA in cruise flight (which would be caused by a higher than optimal pitch attitude in cruise flight) would provide reference to the crew that they are not at the optimal cruise altitude (likely confirmed by the FMS CRZ page information).

There are many compelling reasons for AOA indicators to be installed and understood by flight crews.

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15 minutes ago, rudder said:

On a modern swept wing commercial airliner, the AOA indication is also a good reference for efficiency. A higher than normal AOA in cruise flight (which would be caused by a higher than optimal pitch attitude in cruise flight) would provide reference to the crew that they are not at the optimal cruise altitude (likely confirmed by the FMS CRZ page information).

There are many compelling reasons for AOA indicators to be installed and understood by flight crews.

That can be accomplished without actually seeing the actual angle of the vane.  The computers will work it all out in the background.  Remember if you need the indication, you are far from looking for efficient cruise because you are in the $h!t and trying to get out.  Remember all of the MCAS functions are disabled with AP engaged.

 

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Bottom line - if the crew(s) had AOA indicators and miscompare notification (unfortunately Boeing still refuses to install EICAS on any version of the 737) they may have more effectively diagnosed and responded to the system malfunction as the stick shaker activated and the MCAS system was responding to a single erroneous AOA indication.

In hindsight seems surprising in the age of computer generated EFIS PFD displays that this is not a default configuration.

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The 737 despite being an "all New" 737-MAX is still the same old aircraft designed decades ago.  All they have done is mix and match equipment on top of the old.  Its just makeup on a pig.  The aircraft systems of the 737 need a complete clean slate redesign to become an actual Modern airframe.  It is still decades behind but hey...It's cheap.

I am still a believer in the seat of the pants.  There are only a couple of things that cause an aircraft to pitch like that.  Stabilizer and Elevator (to a extent, especially on the max, the Engine thrust setting).  does is not make sense that if the aircraft is misbehaving in pitch that maybe something in those systems is incorrect.  Nose is pitching down and pulling up does nothing.  Stab Trim.  Hit the switches and start pulling on the wheel.  To me as both a pilot on AME this only makes sense.eliminate the possible cause and reintroduce one at a time to identify the problem.  Turn something on and things go south, turn that back off.

I have a hard time grasping that experienced pilots would fight an aircraft all the way down like this whether they could see the AOA values or not.  A miscompare light would tell you One AOA is bad but what if both are bad?  No miscompare but bad AOA values.  This happened on an A320 a few years ago and they nose dived into the water (XL888).

In that case the aircraft thought everything was normal until every other systems told the computer something was wrong but it didnt know what.  The machine told the pilots and they did nothing to correct the issue by MANUALLY TRIMMING the plane nose up.  Sound familiar?

IMHO pilots are forgetting how to fly and are just automation managers most of the time.  Time and time again we see that plots are forgetting to AVIATE, NAVIGATE, COMMUNICATE.

 

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When pilots used the thumb trim switches I understand it stopped the MCAS trim output,  but did it reverse the MCAS trim output?

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March 21, 2019 / 7:36 PM / Updated 16 minutes ago

American Airlines pilots will test 737 MAX software fix in Boeing simulator

 

3 Min Read

 

CHICAGO (Reuters) - American Airlines pilots will test Boeing Co’s 737 MAX software fix on simulators this weekend, the pilots’ union told Reuters on Thursday, a key step in restoring confidence in the jet after two fatal crashes.

Boeing has been working on a software upgrade for an anti-stall system and pilot displays on its fastest-selling jetliner in the wake of the deadly Lion Air crash in Indonesia in October.

Similarities between the flight path in the Lion Air incident and a fatal Ethiopian Airlines crash on March 10 have raised fresh questions about the system. The two crashes killed a total of 346 people.

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 https://www.aopa.org/news-and-media/all-news/2019/march/20/congressman-concerned-about-foreign-pilot-training?utm_source=epilot&utm_medium=email&utm_content=tts&utm_campaign=190321epilot 'Why didn’t they … fly the airplane?'

'Why didn’t they … fly the airplane?''Why didn’t they … fly the airplane?'

Congressman and pilot questions foreign pilot training, standardsCongressman and pilot questions foreign pilot training, standards

March 20, 2019 By Jim Moore

Two fatal Boeing 737 MAX crashes prompted international grounding, but Rep. Sam Graves, a longtime pilot and Missouri congressman, said foreign pilot training and standards should be scrutinized as much as the aircraft.

Graves, a warbird aficionado who holds an airline transport pilot certificate and is the ranking member of the House Transportation and Infrastructure Committee, said in a March 19 telephone interview that he is concerned about the slow pace of facts coming to light since Ethiopian Airlines Flight 302 crashed shortly after takeoff on March 10, killing all 157 people aboard. The FAA, which initially defended the aircraft’s airworthiness, grounded all 380 of the 737 MAX-8 and MAX-9 aircraft delivered to date on March 13, citing similarities that had come to light between the Ethiopian crash and the loss of another Boeing 737 MAX flown by Indonesia’s Lion Air in October 2018.

The NTSB has participated in the investigations, though an agency spokesman told The New York Times March 17 that any information gleaned by investigators could be made public only by Ethiopian officials. Boeing took the same position, citing longstanding protocol. Physical evidence and data made public to date strongly suggest a problem with the Maneuvering Characteristics Augmentation System, which was designed to activate the stabilizer trim if the aircraft exceeded a safe angle of attack with the autopilot disengaged.

 

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In both crashes, flight telemetry data suggest the pilots fought a losing battle with runaway trim.

 

“We’re concentrating completely on the wrong thing, here,” Graves said. “We’re looking at equipment and equipment failures. You can have that in any aircraft. What I want to concentrate on are the pilots. Why didn’t they just disengage the system and fly the plane?”

Graves said he has talked to FAA and Department of Transportation officials daily since the Ethiopian Airlines crash and has yet to hear any indication of concern that a deadly mechanical defect lurks inside the newest iterations of the bestselling passenger jet that first flew in 1967. He said pilots should be expected to cope with the kind of malfunction that appears to have been involved by simply disabling the system.

“I don’t care if you have a (Piper) Seneca or a 737 MAX, the first thing (you do) is you disengage the system and you fly the plane,” Graves said.

Pilots with 737 experience and other aviation experts told AOPA that the stabilizer trim system can be shut off with switches mounted between the pilots that either can easily reach. It appears U.S. flight crews have done exactly that when responding to similar system problems on the same jets. Pilot and journalist James Fallows, on the same day the FAA grounded the 737 MAX-8 and MAX-9 aircraft, wrote about and republished publicly available Aviation Safety Reporting System submissions from flight crews who had encountered similar situations with very different outcomes—a safe continuation and completion of the flight.

The stabilizer trim switches of a Boeing 737 Max 8 aircraft are located on the center pedestal and can be defeated by either the pilot or the first officer, according to a career pilot familiar with the aircraft. Courtesy photo.
The stabilizer trim switches of a Boeing 737 Max 8 aircraft are located on the center pedestal and can be defeated by either the pilot or the first officer, according to a career pilot familiar with the aircraft. Courtesy photo.

Graves said acting FAA Administrator Dan Elwell and his staff were aware of these reports, and the FAA assured him that none of the incidents represented a threat to flight safety. Bloomberg reported March 19 that a Lion Air 737 MAX encountered an identical problem the day before the fatal October crash, and a third pilot riding in the jump seat advised the crew to cut power to the malfunctioning system. That flight landed safely.

Another longtime pilot and aviation journalist, J. Mac McClellan, wrote in a March 11 article in Air Facts that Boeing engineers must have counted on pilots to quickly disengage any malfunctioning automation feature:

“Though the pitch system in the MAX is somewhat new, the pilot actions after a failure are exactly the same as would be for a runaway trim in any 737 built since the 1960s. As pilots we really don’t need to know why the trim is running away, but we must know, and practice, how to disable it.”

Graves said the Ethiopian government has an incentive to protect the reputation of its government-owned airline, and that worries him when it comes to fact-finding.

“It’s their crown jewel,” Graves said. “They are being very, very careful on who gets to see the data.”

As for the NTSB staff dispatched to participate in the probe, “I’m still waiting to hear just how well they’re working with them, how much they’re allowing them to be part of the process. To be quite honest with you, it does worry me. It’s in the best interest of the world flying public to get this information.”

Graves said that while Congress may ultimately probe the certification process and the FAA’s decision making, as some have suggested, he is more concerned about the training and competence of foreign pilots.

“I’ve got real heartburn when I’m flying on a foreign airline,” Graves said. “If they’re training to U.S. standards, they’re certainly not adhering to U.S. standards.”

Graves worries that foreign carriers are under pressure to fill cockpit seats and may not be taking enough time to teach fundamentals.

“That’s what I’m concerned about … some of these countries are trying to get pilots in the pipeline so fast that they’re teaching them to fly computers” and not providing adequate real-world aviation training, Graves said. “There’s no doubt that technology has made aviation safer, but you’ve got to wonder … technology … does it correct pilot deficiencies, or is it creating pilot deficiencies?”

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41 minutes ago, ckl said:

When pilots used the thumb trim switches I understand it stopped the MCAS trim output,  but did it reverse the MCAS trim output?

ckl, no, the MCAS continued ND trim inputs in 5-second bursts after being "corrected" by using the pickle-switches, (thumb-trim switches on the control wheel). The AoA data on JT610, (not convinced it was the sensor) was 20deg and so the MCAS kept responding with ND trim at 5-second intervals.

I'm not convinced that ET302 is the same accident as JT610. AoA sensors are notoriously problem-free. I think the problem is downstream of the AoA data. Certainly just a SCWAG - there's nothing to go on except the full-ND screwjack.

boestar, good comments on the AoA system. Complexity comes from cost-savings, the challenge being to bring flight crews into the mix. I don't believe AoA data is helpful or would have prevented AF447 or JT610 for example.

"Why didn't they fly the airplane?!", is a logical, apparently-reasonable question to ask and demand the answer to but what we think should have been done does not explain people's behaviour. So expecting that a satisfactory answer to the question would solve the problem is magical thinking and so needs to be reconsidered more broadly and patiently. No one begins ones' day expecting or envisioning the outcomes that these two crews experienced.

Edited by Don Hudson

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Ethiopian ET302 similarities to Lion Air JT610

 
Reports from Ethiopian investigators have implicated the same Angle of Attack (AoA) sensor malfunction that was observed on Lion Air. Lion Air captain AoA sensor read about 22 degrees higher than the First Officer AoA sensor (a large bias error). Initial assessment of Lion Air AoA failure modes did not reveal any obvious electrical malfunction that could create the bias. The simplest explanation was that the AoA vane had been bent, causing a gross aerodynamic offset in the readings. If ET302 encountered the exact same offset, with the likelihood of it being bent exactly the same way not being conceivable, some other factor must be in play. For example, the ARINC 429 representation of AoA uses two's complement fraction binary notation (BNR). It is interesting to note that bit 26 represents 22.5 degrees which would be the bit "flipping" between the Captain and F/O AoA values (all other bits would match).  Is it possible that the ARINC 429 word is getting corrupted (software defect)?  If the ET302 offset was something like 20 or 24, this theory falls apart.
The document is quite lengthy and contains charts etc. so here is the link:

https://www.satcom.guru/2019/03/ethiopian-et302-similarities-to-lion.html#more

 

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March 22, 2019 10:51 am

Updated: March 22, 2019 11:04 am

WestJet will stick with Boeing 737 MAX 8 as first airline looks to cancel order

By Ross Marowits The Canadian Press

WestJet Airlines plans to stick with deliveries of Boeing 737 MAX aircraft once regulators approve the plane for re-entry into service.ory continues below

The Calgary-based airline says it won’t follow the lead of Indonesia’s flag carrier, which cancelled its multibillion-dollar order for 49 MAX 8 jets, citing a loss of confidence after two deadly crashes in the past six months.

READ MORE: Boeing 737 MAX fallout continues as airline seeks to cancel $5B aircraft order

WestJet had expected to add two more of the planes this year to increase its fleet to 13, but Boeing has suspended all future deliveries.

Spokeswoman Lauren Stewart says the 37 remaining deliveries in its order won’t take place until the grounding is lifted and it thoroughly evaluates any upgrades.

WATCH: Some safety features sold as options on Boeing’s 737 MAX jets

2019-03-21T21-35-24.533Z--640x360.jpg?w=670&quality=70&strip=all

“If the grounding has been lifted and the aircraft is approved for re-entry into service by all relevant regulatory bodies, we will take all deliveries as intended,” she wrote in an email.

Stewart said the narrow-body planes remain “a vital part of the fleet,” having performed “safely, reliably and efficiently” since 2017.

“WestJet remains unrelenting in putting safety at the forefront and will thoroughly evaluate processes, procedures and any further required training before these aircraft once again take to the skies.”

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31 minutes ago, Don Hudson said:

ckl, no, the MCAS continued ND trim inputs in 5-second bursts after being "corrected" by using the pickle-switches, (thumb-trim switches on the control wheel). The AoA data on JT610, (not convinced it was the sensor) was 20deg and so the MCAS kept responding with ND trim at 5-second intervals.

I'm not convinced that ET302 is the same accident as JT610. AoA sensors are notoriously problem-free. I think the problem is downstream of the AoA data. Certainly just a SCWAG - there's nothing to go on except the full-ND screwjack.

boestar, good comments on the AoA system. Complexity comes from cost-savings, the challenge being to bring flight crews into the mix. I don't believe AoA data is helpful or would have prevented AF447 or JT610 for example.

"Why didn't they fly the airplane?!", is a logical, apparently-reasonable question to ask and demand the answer to but what we think should have been done does not explain people's behaviour. So expecting that a satisfactory answer to the question would solve the problem is magical thinking and so needs to be reconsidered more broadly and patiently. No one begins ones' day expecting or envisioning the outcomes that these two crews experienced.

I understand that the MCAS stopped trimming until the pickle switches were released and then the MCAS resumed trimming nose down again, but if the pilots leaned on the pickle switches for a period of time, would the aircraft return to a trimmed state, at least temporarily? In other words did the pickle switches only stop the MCAS but did not trim the aircraft in this situation?

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1 hour ago, ckl said:

I understand that the MCAS stopped trimming until the pickle switches were released and then the MCAS resumed trimming nose down again, but if the pilots leaned on the pickle switches for a period of time, would the aircraft return to a trimmed state, at least temporarily? In other words did the pickle switches only stop the MCAS but did not trim the aircraft in this situation?

The MCAS trim inputs can be stopped and reversed with the pickle switches but may restart 5 seconds after the switches are released.

Edited by Arctic Ace

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Using the pickle switches should stop the movement, override and allow the trim to move in the pilot selected direction. When released I presume that the MCAS would then drive it in the direction it was attempting previously. Pilot selection of the pickle switches again would then stop that movement. [gripping the main trim wheel is also an option to stop movement] At some point the pilot should use the stab trim cutout with the result that all trim would be be manual.

On the NG control column movement in the opposite direction of the main electric or autopilot trim should cause a trim cutout. Not sure if that exists on the Max.

So it seems to me that the current (and very old) system of of using the CUTOUT when there is a trim runaway should work. As a guess - either the pilots did not use the CUTOUT or they did and the MCAS system was not shutdown via that action.

Or, the possibility that the different systems 'fought' each other?

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All STS & MCAS trim activity stops when the stab cutoff switches are placed in the OFF position; so does grasping/holding the trim wheel. The action would have prevented the JT610 accident but since the trim wheel is quite busy after takeoff it would have been very difficult to assess its motion as a runaway, especially with a constantly-on stick shaker and other warnings going on.

Engaging the autopilot or selecting flap stops the MCAS. In JT610's case, the crew extended then retracted the flaps. MCAS activity stopped and with the 20deg data, started again when the flaps were up.

ckl, Arctic Ace said it more clearly than I did...the pickle switches override the MCAS and do what the switches were ordering, but the MCAS would continue to operate once the switches were released because of the incorrect AoA data.

Edited by Don Hudson

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6 hours ago, boestar said:

That can be accomplished without actually seeing the actual angle of the vane.  The computers will work it all out in the background.  Remember if you need the indication, you are far from looking for efficient cruise because you are in the $h!t and trying to get out.  Remember all of the MCAS functions are disabled with AP engaged.

 

No.  The computers will only work out what fits their model.  If a condition is outside the range of assumptions of the programmer, as the MCAS failure demonstrates, the computers may generate inappropriate solutions or diagnose the situation as something else.

When the aircraft is approaching an upset, there is no substitute for raw data and direct control.

It may be comforting to suggest that this all goes away when the AP is engaged, but we have to remember that there are limitations on AP engagement.  If the aircraft is this far out of trim,  is it certain the AP would function?

All IMO.

Vs

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I do not believe engaging the autopilot would have been an option with an extreme out of trim condition. Stick shaker, airspeed warnings, all close to the ground, would be such a distraction it does not surprise me that they did not get to the stab trim cutout switches. 

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- I don't believe the auto pilot could have been engaged with a faulty stall warning

-the control column (not the pickle switches) activated stabilizer cutout switches are on the MAX (control column movement opposite of trim direction) and will stop operation of the main electric and autopilot trim but is inhibited during MCAS operation of the trim

- the Stab Trim override switch on the centre console when positioned to OVRD overrides the control column activated stabilizer cutout switches

- the pickle switches actuate the trim motor through the main elec stab trim circuit

- the auto pilot uses the auto pilot stab trim circuit

-  either of the STAB TRIM PRI and STAB TRIM B/U cutout switches will disconnect both the main and autopilot electric trim inputs to the stabilizer trim motor (different than the NG)

- extreme cases of mis-trim may require the efforts of both pilots on the trim wheel and/or aerodynamic unloading to trim manually

- last memory item on the Runaway Stabilizer QRC for pretty much all 737's is Grasp and Hold the trim wheel if the runaway continues after the Stab Trim Cutout switches have been positioned to cutout. All the switches just provide electrical commands to the trim motor. The cutout switches just cut these electrical connections off so I'm guessing the last memory item is in the event of the motor somehow being powered even though all switch connections have been terminated but that's just a WAG.

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If trimming with the pickle switches stops/helps/impedes the problem why all the focus on trying to find the appropriate checklist (Lionair) With proper training and experience I think most pilots would lean toward a stabilizer problem. No question that having multiple systems barking at you can muddy your focus, but you still have ground speed/power settings/artificial horizon, and in both of these incidents a visual horizon. 

There is a faulty system on the Boeing that needs a remedy, but the larger issue appears to be basic piloting ability. Systems do fail, we've all been grilled in the sim - fly the airplane first.

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“Though the pitch system in the MAX is somewhat new, the pilot actions after a failure are exactly the same as would be for a runaway trim in any 737 built since the 1960s. As pilots we really don’t need to know why the trim is running away, but we must know, and practice, how to disable it.”

 

This paragraph from Maclellan sums it up perfectly IMHO.

 

T9

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7 minutes ago, Tango Niner said:

“Though the pitch system in the MAX is somewhat new, the pilot actions after a failure are exactly the same as would be for a runaway trim in any 737 built since the 1960s. As pilots we really don’t need to know why the trim is running away, but we must know, and practice, how to disable it.”

 

This paragraph from Maclellan sums it up perfectly IMHO.

 

T9

From whom?🤔

Edited by blues deville

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On 3/22/2019 at 9:54 AM, Malcolm said:

Another longtime pilot and aviation journalist, J. Mac McClellan, wrote in a March 11 article in Air Facts that Boeing engineers must have counted on pilots to quickly disengage any malfunctioning automation feature:

“Though the pitch system in the MAX is somewhat new, the pilot actions after a failure are exactly the same as would be for a runaway trim in any 737 built since the 1960s. As pilots we really don’t need to know why the trim is running away, but we must know, and practice, how to disable it.”

From Malcolm’s post above.

1) Boeing needs to fix this, but ALSO:

2) Pilots need better training on the aircraft. The cutout switches have been present on every B737 since the -100.

IMHO

T9

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2 hours ago, Tango Niner said:

“Though the pitch system in the MAX is somewhat new, the pilot actions after a failure are exactly the same as would be for a runaway trim in any 737 built since the 1960s. As pilots we really don’t need to know why the trim is running away, but we must know, and practice, how to disable it.”

 

This paragraph from Maclellan sums it up perfectly IMHO.

 

T9

This is incorrect. 

On all previous B737s the first action in the event of a stab trim runaway is to move the control column in the opposite direction. Doing this engages the mechanical stab brake stopping any further stab movement. 

In an MCAS event the stab brake is bypassed and doesn’t engage as in all previous B737s. 

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1 minute ago, Ex 9A Guy said:

This is incorrect. 

On all previous B737s the first action in the event of a stab trim runaway is to move the control column in the opposite direction. Doing this engages the mechanical stab brake stopping any further stab movement. 

In an MCAS event the stab brake is bypassed and doesn’t engage as in all previous B737s. 

My point was the part about disabling it. As in, knowing, if needed, to hit the stab trim cutout switches- which have been present on the 737 since its mid-60’s inception.

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