Ethiopian Airlines plane crashes on way to Nairobi

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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by MadMacs » Tue May 07, 2019 3:21 pm

Deanw wrote:
Tue May 07, 2019 7:10 am
MadMacs wrote:
Mon May 06, 2019 11:24 pm
The 737 was developed from the 707 sharing common cockpit and fuselage components.
40/50 years ago maybe, but I very much doubt the NG and Max versions share any cockpit or instrument sensors with those early aircraft.
Not sure how grandfathering the newer models works but other than the glass cockpit as opposed to the old analogue gauges, they have to be the same as the original. I also think we're getting sidetracked with this probe issue, since the one in the video might not even be the same as the 737 ones. :)
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by rainier » Tue May 07, 2019 4:39 pm

I think we can take it that the 737 has reached end of line. Boeing HAS to replace it with a new airframe now. It should be seen as opportunity to make something really good.
Who said the sky is the limit ? I think not.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Ugly Duckling » Tue May 07, 2019 5:25 pm

rainier wrote:
Tue May 07, 2019 4:39 pm
I think we can take it that the 737 has reached end of line. Boeing HAS to replace it with a new airframe now. It should be seen as opportunity to make something really good.
viewtopic.php?f=9&t=216704&p=2028612#p2028612
Boeing were leveraging the supply chain for the 737 to the Max :lol: with this product rather than go clean sheet like the Europeans have done.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by RiNCEw1ND » Tue May 07, 2019 7:24 pm

MadMacs wrote:
Tue May 07, 2019 3:21 pm
Deanw wrote:
Tue May 07, 2019 7:10 am
MadMacs wrote:
Mon May 06, 2019 11:24 pm
The 737 was developed from the 707 sharing common cockpit and fuselage components.
40/50 years ago maybe, but I very much doubt the NG and Max versions share any cockpit or instrument sensors with those early aircraft.

Not sure how grandfathering the newer models works but other than the glass cockpit as opposed to the old analogue gauges, they have to be the same as the original. I also think we're getting sidetracked with this probe issue, since the one in the video might not even be the same as the 737 ones. :)
Pitot probes and AOA vanes are totally different from classic to NG. Not sure about the -100/200 737 however.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Vlerkies » Tue May 07, 2019 10:23 pm

Would be great when someone stands up and says the plane is safe (other than the manufacturer with 2 down and hundreds of deceased on
their hands)

Passenger: till you figure it out, I do not want to be seated on that particular aircraft

BA had one local, is it still grounded?
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Stephan van Tonder » Thu May 09, 2019 10:57 am

Vlerkies wrote:
Tue May 07, 2019 10:23 pm
Would be great when someone stands up and says the plane is safe (other than the manufacturer with 2 down and hundreds of deceased on
their hands)

Passenger: till you figure it out, I do not want to be seated on that particular aircraft

BA had one local, is it still grounded?
they are all grounded world wide until the certifying agencies says they are not. At this point it was guessed at somewhere in august. It will not be boeing only that says they are safe to fly. You can bet your bottom dollar that this time they are being looked at in a lot more detail than before.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Ned Yakman » Sun May 12, 2019 12:04 am

This article by Sean Broderick of the authoratative Aviation Week & Space Technology magazine and also published on ATW Online:

US pilots stunned by Ethiopian MAX crash simulator scenario
ATW Plus
Sean Broderick
Fri, 2019-05-10 12:13
A simulator session flown by a US-based Boeing 737 MAX crew that mimicked a key portion of the Ethiopian Airlines ET302 crash sequence suggests the Ethiopian crew faced a near-impossible task of getting the aircraft back under control, and underscores the importance of pilots understanding severe runaway trim recovery procedures.

Details of the session, shared with ATW, were flown voluntarily as part of routine, recurrent training. Its purpose: practice recovering from a scenario in which the aircraft was out of trim and wanting to descend while flying at a high rate of speed. This is what the ET302 crew faced when it toggled cutout switches to de-power the MAX’s automatic stabilizer trim motor, disabling the maneuvering characteristics augmentation system (MCAS) that was erroneously trimming the horizontal stabilizer nose-down.

In such a scenario, once the trim motor is de-powered, pilots must use the hand-operated manual trim wheels to adjust the stabilizers. But they also must keep the aircraft from descending by pulling back on the control columns to deflect the elevator portions of the stabilizer upward. Aerodynamic forces from the nose-up elevator deflection make the entire stabilizer more difficult to move, and higher airspeed exacerbates the issue.

The US crew tested this by setting up a 737 Next Generationsimulator at 10,000 ft., 250 kt. and 2 deg. nose up stabilizer trim. This is slightly higher altitude, but otherwise similar to what the ET302 crew faced as it de-powered the trim motors 3 min. into the 6 min. flight, and about 1 min. after the first uncommanded MCAS input.Leading up to the scenario, the Ethiopian crew used column-mounted manual electric trim to counter some of the MCAS inputs, but did not get the aircraft back to level trim, as the 737 manual instructs before de-powering the stabilizer trim motor. The crew also did not reduce their unusually high speed.

What the US crew found was eye-opening: keeping the aircraft level required significant aft-column pressure by the captain, and aerodynamic forces prevented the first officer from moving the trim wheel a full turn. They resorted to a little-known procedure to regain control.

The crew repeatedly executed a three-step process known as the roller coaster: First, let the aircraft’s nose drop, removing elevator nose-down force.Second, crank the trim wheel, inputting nose-up stabilizer, as the aircraft descends. Third, pull back on the yokes to raise the nose and slow the descent.

The excessive descent rates during the first two steps meant the crew got as low as 2,000 ft. during the recovery.

The Ethiopian Ministry of Transport preliminary report on the March 10 ET302 accident suggests the crew attempted to use manual trim after de-powering the stabilizer motors, but determined it “was not working,” the report said. A constant trust setting at 94% N1 meant ET302’s airspeed increased to the 737 MAX’s maximum (Vmo), 340 kt., soon after the stabilizer trim motors were cut off, and did not drop below that level for the remainder of the flight. The pilots, struggling to keep the aircraft from descending, also maintained steady to strong aft control-column inputs from the time MCAS first fired through the end of the flight.

The US crew’s session and a video posted recently by YouTube’s Mentour Pilot that shows a similar scenario inside a simulator suggest the resulting forces on ET302’s stabilizer would have made it nearly impossible to move by hand.

Neither the current 737 flight manual nor any MCAS-related guidance issued by Boeing in the wake of October’s crash of Lion Air JT610, when MCAS first came to light for most pilots, discuss the roller-coaster procedure for recovering from severe out-of-trim conditions. The 737 manual explains that “effort required to manually rotate the stabilizer trim wheels may be higher under certain flight conditions,” but does not provide details.

The pilot who shared the scenario said he learned the roller coaster procedure from excerpts of a 737-200 manual posted in an online pilot forum in the wake of the MAX accidents. It is not taught at his airline.

Boeing’s assumption was that erroneous stabilizer nose-down inputs by MCAS, such as those experienced by both the JT610 and ET302 crews, would be diagnosed as runaway stabilizer. The checklist to counter runaway stabilizer includes using the cutout switches to de-power the stabilizer trim motor. The ET302 crew followed this, but not until the aircraft was severely out of trim following the MCAS inputs triggered by faulty angle-of-attack (AOA) data that told the system the aircraft’s nose was too high.

Unable to move the stabilizer manually, the ET302 crew moved the cutout switches to power the stabilizer trim motors—something the runaway stabilizer checklist states should not be done. While this enabled their column-mounted electric trim input switches, italso re-activated MCAS, which again received the faulty AOA data and trimmed the stabilizer nose down, leading to a fatal dive.

The simulator session underscored the importance of reacting quickly to uncommanded stabilizer movements and avoiding a severe out-of-trim condition, one of the pilots involved said. “I don’t think the situation would be survivable at 350 kt. and below 5,000 ft.,” this pilot noted.

The ET302 crew climbed through 5,000 ft. shortly after de-powering the trim motors, and got to about 8,000 ft.—the same amount of altitude the US crew used up during the roller-coaster maneuvers—before the final dive.

A second pilot not involved in the session but who reviewed the scenario’s details said it highlighted several training opportunities.

“This is the sort of simulator experience airline crews need to gain an understanding of how runaway trim can make the aircraft very difficult to control, and how important it is to rehearse use of manual trim inputs,” this pilot said.

While Boeing’s runaway stabilizer checklist does not specify it, the second pilot recommended a maximum thrust of 75% N1 and a 4 deg. nose-up pitch to keep airspeed under control.

Boeing is developing modifications to MCAS as well as additional training. Simulator sessions are expected to be integrated into recurrent training, and may be required by some regulators, and opted for by some airlines, before pilots are cleared to fly MAXs again. The MAX fleet has been grounded since mid-March, a direct result of the two accidents.

Sean Broderick, sean.broderick@aviationweek.com
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Antman » Sun May 12, 2019 10:12 am

Ned Yakman wrote:
Sun May 12, 2019 12:04 am

The excessive descent rates during the first two steps meant the crew got as low as 2,000 ft. during the recovery.

The ET302 crew climbed through 5,000 ft. shortly after de-powering the trim motors, and got to about 8,000 ft.—the same amount of altitude the US crew used up during the roller-coaster maneuvers—before the final dive.
People seem too forget that Bole Intl Airport and surrounding terrain elevation is 7600 ft which means the Ethiopian Pilots only had about 2000 ft to play with that US crew only recovered at 2000 ft after starting at 10 000 ft for a height loss of 8000 ft, so even with the roller coaster maneuver they would have crashed.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by heisan » Sun May 12, 2019 3:13 pm

Antman wrote:
Sun May 12, 2019 10:12 am
Ned Yakman wrote:
Sun May 12, 2019 12:04 am

The excessive descent rates during the first two steps meant the crew got as low as 2,000 ft. during the recovery.

The ET302 crew climbed through 5,000 ft. shortly after de-powering the trim motors, and got to about 8,000 ft.—the same amount of altitude the US crew used up during the roller-coaster maneuvers—before the final dive.
People seem too forget that Bole Intl Airport and surrounding terrain elevation is 7600 ft which means the Ethiopian Pilots only had about 2000 ft to play with that US crew only recovered at 2000 ft after starting at 10 000 ft for a height loss of 8000 ft, so even with the roller coaster maneuver they would have crashed.
The altitudes given were AGL - so while tight, they did have some room for this manoeuvre.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by heisan » Sun May 12, 2019 3:16 pm

Some interesting comments from someone who got to test MCAS:

https://www.quora.com/Why-can-t-a-well- ... ch-upwards
Why can’t a well-trained pilot flying the 737-Max compensate for the tendency of the aircraft to stall due to engine placement which may cause the plane to naturally pitch upwards?

Hachi Ko, Pilot (ATP) & Air Traffic Controller (FAA Terminal ATC-12)

I’ve flown the MAX (as part of a test program) with the MCAS both enabled and disabled (disabling only the MCAS can’t normally be done).

With the MCAS functioning, the MAX feels like flying the older NG models, such as the 737–800.

When the MCAS is disabled, the MAX is not any more difficult to handle than the NG… the problem is that it handles differently from the NG. There’s no issue with the airplane suddenly wanting to pitch up and stall or anything like that — it’s more subtle than that. If the pilot is expecting the airplane to handle like an NG, he might be surprised by the way the airplane behaves, particularly if he’s not paying attention, and could get into trouble (too close to stalling). It would be the same as telling a pilot that he doesn’t need any training to fly the 757… it just flies like the 737. Well… that’s not true, and the pilot could get into trouble flying the 757 if he’s expecting it to feel exactly like the 737.

That’s where the issue is. Boeing promised all of its customers (the airlines) that the MAX wouldn’t require any additional training for their 737NG pilots. When Boeing’s test pilots discovered that the MAX handling was too different for this, the engineers used the control feel and augmentation systems (which are already in place on the NG for things like Mach Trim, Speed Trim, and Elevator Feel) to implement another software routine, which they called MCAS.

This would have been all fine and dandy, except that we have every indication now that MCAS was poorly implemented (lack of redundancy, etc.). MCAS itself is fine, but there weren’t enough safeguards built in to prevent it from misbehaving and being overly-aggressive when it received erroneous data from faulty sensors.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Ned Yakman » Mon May 13, 2019 11:38 am

https://www.bloomberg.com/news/articles ... -documents

Southwest, Pilot Unions Get Subpoenas for 737 Max Documents
Labor groups required to produce information on new jetliner
Plane has been grounded almost two months after deadly crashes


Southwest Airlines Co. joined the list of organizations -- currently including pilot unions from Southwest, United Continental Holdings Inc. and American Airlines Group Inc. -- receiving federal grand jury subpoenas for documents relating to Boeing Co.'s grounded 737 Max.

Southwest is cooperating fully with the request, company spokeswoman Brandy King said in a statement Saturday. The airline has the largest Max fleet, with 34 planes and additional orders for more than 200.

The Southwest Airlines Pilots Association was given until May 24 to comply with the demand from the U.S. Justice Department's criminal division, union President Jon Weaks said Friday. The Air Line Pilots Association, which represents aviators at United and other carriers, said it also received a subpoena. The Allied Pilots Association, whose members work for American, got one as well, said a person familiar with the matter.

Investigators are probing Boeing's development of the Max, a popular single-aisle model that's been grounded since mid-March after crashing twice in five months. In both disasters, a new software system known as MCAS repeatedly shoved the nose of the doomed jets down, eventually overwhelming pilots. Congress and the Transportation Department also are examining the Federal Aviation Administration's approval of the aircraft.

"I don't know what aspect they are investigating," Weaks said in an interview. "They just want to know what we have on the Max. We knew it would come eventually."

Max Operators
The Southwest pilots' union will probably seek an extension of the deadline because of the time needed to search through documents, emails and other papers for Max-related items, he said.

At least one former Boeing engineer has also been subpoenaed in connection with the Max, the best-selling plane in the company's history.

U.S. investigators began a probe weeks after a Lion Air Max 8 plunged into the Java Sea off the coast of Indonesia on Oct. 29. An Ethiopian Airlines jet crashed minutes after takeoff from Addis Ababa on March 10, bringing the death toll from the two accidents to 346. The Max, the newest version of the 737, began flying commercially in May 2017.

A law enforcement agent with the Transportation Department Inspector General's office has contacted at least one FAA official to ask how the MCAS system was certified, Bloomberg reported in March. Another facet of the inquiry has focused on why Boeing didn't flag the feature in pilot manuals.

A Congressional hearing is set for May 15.
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Ned Yakman » Wed May 15, 2019 2:27 pm

From today's New York Times: https://www.nytimes.com/2019/05/14/busi ... crash.html

Before Ethiopian Crash, Boeing Resisted Pilots' Calls for Aggressive Steps on 737 Max


Weeks after the first fatal crash of the 737 Max, pilots from American Airlines pressed Boeing executives to work urgently on a fix. In a closed-door meeting, they even argued that Boeing should push authorities to take an emergency measure that would likely result in the grounding of the Max.

The Boeing executives resisted. They didn't want to rush out a fix, and said they expected pilots to be able to handle problems.

Mike Sinnett, a vice president at Boeing, acknowledged that the manufacturer was assessing potential design flaws with the plane, including new anti-stall software. But he balked at taking a more aggressive approach, saying it was not yet clear that the new system was to blame for the Lion Air crash, which killed 189 people.

"No one has yet to conclude that the sole cause of this was this function on the airplane," Mr. Sinnett said, according to a recording of the Nov. 27 meeting reviewed by The New York Times.

Less than four months later, an Ethiopian Airlines flight crashed, killing all 157 people on board. The flawed anti-stall system played a role in both disasters.

Boeing is facing intense scrutiny for the design and certification of the Max, as well as for its response to the two crashes. There are multiple investigations into the development of the Max. And in recent days, unions representing pilots from American Airlines and Southwest Airlines have received federal grand jury subpoenas for any documents related to Boeing's communications about the jet, according to three people with knowledge of the matter.

The Federal Aviation Administration is also under fire for its role in approving the Max, and its decision to wait for days after the second crash to ground the plane. At a Wednesday congressional hearing, lawmakers will grill federal regulators about how the Max was certified.

Boeing declined to comment on the November meeting. "We are focused on working with pilots, airlines and global regulators to certify the updates on the Max and provide additional training and education to safely return the planes to flight," the company said in a statement.

American Airlines said in a statement that it was "confident that the impending software updates, along with the new training elements Boeing is developing for the Max, will lead to recertification of the aircraft soon."

Mike Sinnett, a Boeing vice president, balked at taking a more aggressive approach to issues with the 737 Max during a meeting with American Airlines pilots in November.

The hourlong November meeting, inside a windowless conference room at the Fort Worth headquarters of the American Airlines pilots' union, was confrontational at times. At the table was Mr. Sinnett, along with Craig Bomben, a top Boeing test pilot, and one of the company's senior lobbyists, John Moloney. They faced several union leaders, many of them angry at the company.

Michael Michaelis, an American pilot, argued that Boeing should push the F.A.A. to issue what is known as an emergency airworthiness directive.

The F.A.A. had already issued one directive after the Lion Air crash, instructing airlines to revise their flight manuals to include information on how to respond to a malfunction of the anti-stall system known as MCAS. But Mr. Michaelis pushed Boeing to consider calling for an additional one to update the software.

Such a procedure would have required Boeing and airlines in the United States to take immediate action to ensure the safety of the Max, and would have likely taken the jet out of service temporarily.

"My question to you, as Boeing, is why wouldn't you say this is the smartest thing to do?" Mr. Michaelis said. "Say we're going to do everything we can to protect that traveling public in accordance with what our pilots unions are telling us."

Mr. Sinnett didn't budge, saying that it remained unclear that the new software, which automatically pushes the plane's nose down, was responsible for the Lion Air crash. He added that he felt confident that pilots had adequate training to deal with a problem, especially now that pilots - who were not initially informed about the new system - were aware of it.

"You've got to understand that our commitment to safety is as great as yours," Mr. Sinnett said in the meeting. "The worst thing that can ever happen is a tragedy like this, and the even worse thing would be another one."

The pilots expressed frustration that Boeing did not inform them about the new software on the plane until after the Lion Air crash.

"These guys didn't even know the damn system was on the airplane, nor did anybody else," said Mr. Michaelis, the union's head of safety.

Another American pilot, Todd Wissing, expressed frustration that no mention of the system had been included in the training manual for the 737 Max.

At the meeting, Boeing executives acknowledged they were looking into potential flaws in the design of the jet.

"I would think that there would be a priority of putting explanations of things that could kill you," Mr. Wissing said.

The Boeing executives, Mr. Sinnett and Mr. Bomben, explained that the company did not believe that pilots needed to know about the software, because they were already trained to deal with scenarios like the one on the doomed Lion Air flight. All pilots are expected to know how to take control of an aircraft when the plane's tail begins moving in an uncontrolled way because of a malfunction, nudging the aircraft toward the ground.

"The assumption is that the flight crews have been trained," Mr. Sinnett said in the meeting. He added later: "Rightly or wrongly, that was the design criteria and that's how the airplane was certified with the system and pilot working together."

When the pilots pressed Boeing to consider encouraging the F.A.A. to issue an emergency airworthiness directive, Mr. Sinnett made the case against moving too quickly.

"We don't want to rush and do a crappy job of fixing the right things and we also don't want to fix the wrong things," Mr. Sinnett said, later adding, "For flight-critical software, I don't think you want us to rush, rush it faster."

Mr. Sinnett acknowledged that the company was looking into potential mistakes in the design of the jet.

"One of the questions will be, is our design assumption wrong?" Mr. Sinnett said. "We're going through that whole thought process of, were our assumptions really even valid when we did this?"

But he remained steadfast that pilots should know how to handle a malfunction of the new software on the plane, given their existing training.

As the meeting was concluding, Dennis Tajer, spokesman for the union, asked the Boeing executives whether they were still confident in the Max.

"Do you feel comfortable that the situation is under control today, before any software fix is implemented?" he asked.

Mr. Sinnett replied immediately: "Absolutely."
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Jack Welles » Wed May 15, 2019 2:55 pm

The mind boggles to think of the money involved and how difficult it must be to make objective decisions when so much is riding on the outcomes.

As for the tech details that the pilots have to contend with - eish! - where's my Hughes 300?
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by love2fly » Thu May 16, 2019 10:37 am

Apologies if this suggestion has been raised as this thread gets bigger and bigger.
Also, I am not a pilot but an enthusiast of all things flying....

Would it not be a possible solution that the MCAS system be limited in how much input it can make, ie x no of degrees of stabilizer/trim, as it is my understanding that trim is there to fine tune and the pilot there to "fly"?
So the MCAS is given one attempt and thereafter it is up to pilot inputs and when happy they reset MCAS back to zero and continue?
In the same way that ABS/ESP etc can be full on, race or "off"?

Just a suggestion from a less informed individual.....
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Re: Ethiopian Airlines plane crashes on way to Nairobi

Unread post by Wlotzkas » Thu May 16, 2019 11:38 am

I have a few questions:
1: On the runaway stabilizer checklist in the flight crew operations manual, it clearly state disengage AP, then auto throttle, then trim cutout switches. But why is there another "if" after trim cutout switches (grab and hold the trim wheel) in case runaway continues? There is not another "if" in case the AP or auto throttle do not disengage. Is that event handled in another checklist? Or might there be another way (other than a wiring problem or cutout switches failing) that will result in continued trim after the switches are at cutout that must be solved by holding the trim wheel? It seems a cutout switch failure is handled in the checklist, but not a failure of AP or auto throttle disconnect.

2: What happens if the pilot commands trim up and the MCAS commands trim down simultaneously? Which one have preference, or will the trim motor stop in that event? (two commands cancelling each other out?)

3: How much momentum is there in the trim wheel? Is it physically possible to "Grasp and hold" it to stop rotation from a fast spinning state without losing a finger or other injury? How practical is this solution?
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