737 MAX 8 Ethiopian si schianta subito dopo il decollo da Addis Abeba

ILM4rcio

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Qui un articolo del Seattle Times, pensavo fosse stato già postato.
Si fa riferimento ad una procedura per poter riprendere i comandi quando le forze attive sullo stabilizzatore sono eccessive, sarebbe stata eliminata dal manuale dal 737-200 in poi perchè ritenuta ormai inutile ed obsoleta.
The pilots of the Ethiopian Airlines 737 MAX that crashed last month appear to have followed the emergency procedure laid out by both Boeing and the Federal Aviation Administration — cutting off the suspect flight-control system — but could not regain control and avert the plunge that killed all 157 on board.
Press reports citing people briefed on the crash investigation’s preliminary findings said the pilots hit the system-cutoff switches as Boeing had instructed after October’s Lion Air MAX crash, but couldn’t get the plane’s nose back up. They then turned the system back on before the plane nose-dived into the ground.
While the new software fix Boeing has proposed will likely prevent this situation recurring, if the preliminary investigation confirms that the Ethiopian pilots did cut off the automatic flight-control system, this is still a nightmarish outcome for Boeing and the FAA.
It would suggest the emergency procedure laid out by Boeing and passed along by the FAA after the Lion Air crash is wholly inadequate and failed the Ethiopian flight crew.

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A local expert, former Boeing flight-control engineer Peter Lemme, recently explained how the emergency procedure could fail disastrously. His scenario is backed up by extracts from a 1982 Boeing 737-200 Pilot Training Manual posted to an online pilot forum a month ago by an Australian pilot.
That old 737 pilot manual lays out a scenario where a much more elaborate pilot response is required than the one that Boeing outlined in November and has reiterated ever since. The explanation in that manual from nearly 40 years ago is no longer detailed in the current flight manual.
Just a week after the Oct. 29 Lion Air crash, Boeing sent out an urgent bulletin to all 737 MAX operators across the world, cautioning them that a sensor failure could cause a new MAX flight-control system to automatically swivel upward the horizontal tail — also called the stabilizer — and push the jet’s nose down.
Boeing’s bulletin laid out a seemingly simple response: Hit a pair of cutoff switches to turn off the electrical motor that moves the stabilizer, disabling the automatic system — known as the Maneuvering Characteristics Augmentation System, or MCAS. Then swivel the tail down manually by turning a large stabilizer trim wheel, next to the pilot’s seat, that connects mechanically to the tail via cables.
Boeing has publicly contended for five months that this simple procedure was all that was needed to save the airplane if MCAS was inadvertently activated.
In a November television interview on the Fox Business Network, Boeing Chief Executive Dennis Muilenburg, when asked if information had been withheld from pilots, cited this procedure as “part of the training manual” and said Boeing’s bulletin to airlines “pointed to that existing flight procedure.”
Vice president Mike Sinnett repeatedly described the procedure as a “memory item,” meaning a routine that pilots may need to do quickly without consulting a manual and so must commit to memory.
But Lemme said the Ethiopian pilots most likely were unable to carry out that last instruction in the Boeing emergency procedure — because they simply couldn’t physically move that wheel against the heavy forces acting on the tail.
“The forces on the tail could have been too great,” Lemme said. “They couldn’t turn the manual trim wheel.”
The stabilizer in the Ethiopian jet could have been in an extreme position with two separate forces acting on it:
MCAS had swiveled the stabilizer upward by turning a large mechanical screw inside the tail called the jackscrew. This is pushing the jet’s nose down.
But the pilot had pulled his control column far back in an attempt to counter, which would flip up a separate movable surface called the elevator on the trailing edge of the tail.
The elevator and stabilizer normally work together to minimize the loads on the jackscrew. But in certain conditions, the elevator and stabilizer loads combine to present high forces on the jackscrew and make it very difficult to turn manually.
As the jet’s airspeed increases — and with nose down it will accelerte — these forces grow even stronger.
In this scenario, the air flow pushing downward against the elevator would have created an equal and opposite load on the jackscrew, a force tending to hold the stabilizer in its upward displacement. This heavy force would resist the pilot’s manual effort to swivel the stabilizer back down.
This analysis suggests the stabilizer trim wheel at the Ethiopian captain’s right hand could have been difficult to budge. As a result, the pilots would have struggled to get the nose up and the plane to climb.
If after much physical exertion failed, the pilots gave up their manual strategy and switched the electric trim system back on — as indicated in the preliminary reports on the Ethiopian flight — MCAS would have begun pushing the nose down again.
Boeing on Wednesday issued a statement following the first account, published Tuesday night by The Wall Street Journal, that the Ethiopian pilots had followed the recommended procedures.
“We urge caution against speculating and drawing conclusions on the findings prior to the release of the flight data and the preliminary report,” Boeing said.
However, a separate analysis done by Bjorn Fehrm, a former jet-fighter pilot and an aeronautical engineer who is now an analyst with Leeham.net, replicates Lemme’s conclusion that excessive forces on the stabilizer trim wheel led the pilots to lose control.
Fehrm collaborated with a Swedish pilot for a major European airline to do a simulator test that recreated the possible conditions in the Ethiopian cockpit.
A chilling video of how that simulator test played out was posted to YouTube and showed exactly the scenario envisaged in the analysis, elevating it from plausible theory to demonstrated possibility.
The Swedish pilot is a 737 flight instructor and training captain who hosts a popular YouTube channel called Mentour Pilot, where he communicates the intricate details of flying an airliner. To protect his employment, his name and the name of his airline are not revealed, but he is very clearly an expert 737 pilot.
In the test, the two European pilots in the 737 simulator set up a situation reflecting what happens when the pre-software fix MCAS is activated: They moved the stabilizer to push the nose down. They set the indicators to show disagreement over the air speed and followed normal procedures to address that, which increases airspeed.
They then followed the instructions Boeing recommended and, as airspeed increases, the forces on the control column and on the stabilizer wheel become increasingly strong.
After just a few minutes, with the plane still nose down, the Swedish 737 training pilot is exerting all his might to hold the control column, locking his upper arms around it. Meanwhile, on his right, the first officer tries vainly to turn the stabilizer wheel, barely able to budge it by the end.
If this had been a real flight, these two very competent 737 pilots would have been all but lost.
The Swedish pilot says at the start of the video that he’s posting it both as a cautionary safety alert but also to undercut the narrative among some pilots, especially Americans, that the Indonesian and Ethiopian flight crews must have been incompetent and couldn’t “just fly the airplane.”
Early Wednesday, the Swedish pilot removed the video at the insistence of his airline.
More detailed instructions that conceivably could have saved the Ethiopian plane are provided in the 1982 pilot manual for the old 737. As described in the extract posted by the Australian pilot, they require the pilot to do something counterintuitive: to let go of the control column for a brief moment.
As Lemme explains, this “will make the nose drop a bit,” but it will relax the force on the elevator and on the jackscrew, allowing the pilot to crank the stabilizer trim wheel. The instructions in the old manual say that the pilot should repeatedly do this: Release the control column and crank the stabilizer wheel, release and crank, release and crank, until the stabilizer is swiveled back to where it should be.
The 1982 manual refers to this as “the ‘roller coaster’ technique” to trim the airplane, which means to get it back on the required flight path with no force pushing it away from that path.
“If nose-up trim is required, raise the nose well above the horizon with elevator control. Then slowly relax the control column pressure and manually trim nose-up. Allow the nose to drop below the horizon while trimming (manually). Repeat this sequence until the airplane is trim,” the manual states.
The Australian pilot also posted an extract from Boeing’s “Airliner” magazine published in May 1961, describing a similar technique as applied to Boeing’s first jet, the 707.
Clearly this unusual circumstance of having to move the stabilizer manually while maintaining a high stick force on the control column demands significant piloting skill.
“We learned all about these maneuvers in the 1950-60s,” the pilot wrote on the online forum. “Yet, for some inexplicable reason, Boeing manuals have since deleted what was then — and still is — vital handling information for flight crews.”
Aviation safety consultant John Cox, chief executive of Safety Operating Systems and formerly the top safety official for the Air Line Pilots Association, said that’s because in the later 737 models that followed the -200, what was called a “runaway stabilizer” ceased to be a problem.
Cox said he was trained on the “roller coaster’ technique” back in the 1980s to deal with that possibility, but that “since the 737-300, the product got so reliable you didn’t have that failure,” said Cox.
However, he added, the introduction of MCAS in the 737 MAX creates a condition similar to a runaway stabilizer, so the potential for the manual stabilizer wheel to seize up at high airspeed has returned.
Cox said the failure of both Boeing and the FAA to warn pilots of this possibility will be “a big issue” as the Ethiopian crash is evaluated.
“I don’t think Boeing realized the complexity of the failure,” he said.
The procedure Boeing recommended to airlines after the Lion Air crash, which was repeated in an airworthiness directive issued by the FAA, includes a line near the bottom that “higher control forces may be needed to overcome any stabilizer nose-down” position. The instructions add that the pilots can use the electric system to neutralize the forces on the control column before hitting the cut-out switches.
But there’s no indication whatever in the wording that this is essential, and that heavy forces could render the manual stabilizer wheel almost immovable if the control column is not relaxed.
It’s possible the Ethiopian pilots, hyper alert after the Lion Air accident to the possibility that MCAS had activated, jumped straight to the end of the procedure checklist and hit the cut-off switches before attempting even to counter the nose-down movement with the thumb switches on the control column.
That would have subjected them almost immediately to the high tail forces that could have made recovery impossible.
The good news for Boeing is that the proposed software fix announced for MCAS should prevent the failure that led to this scenario in the cockpit.
I think the MAX will be safe with the improved MCAS,” said Fehrm of Leeham.net.
On Wednesday, CEO Muilenburg joined Boeing test pilots aboard a 737 MAX 7 flight out of Boeing Field for a demonstration of the MCAS software fix and a test of various failure conditions. “The software update worked as designed,” Boeing said.
The bad news for Boeing is twofold, according to Fehrm. First, the original MCAS design was badly flawed and appears to be the principal cause of the Lion Air crash. Second, the procedure Boeing offered after that accident to keep planes safe now appears to have been woefully inadequate and may have doomed the Ethiopian Airlines jet.
On Wednesday the FAA , facing worldwide skepticism of its oversight, announced that it is establishing a team including foreign regulators to conduct a “comprehensive review of the certification of the automated flight control system on the Boeing 737 MAX aircraft.”
The Joint Authorities Technical Review, chaired by former NTSB Chairman Chris Hart and including experts from the FAA, NASA, and international aviation authorities, will evaluate all aspects of MCAS, including its design and pilots’ interaction with the system.
The preliminary investigation report into the Ethiopian crash is expected early Thursday and should offer definitive detail on what happened in the cockpit.
https://www.seattletimes.com/busine...-737-max-may-have-failed-on-ethiopian-flight/
 

freez267

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Questi aspetti economici, mi sembrano un po, la punta dell' iceberg. C' è da capire il futuro dell' aereo, ordinato in 5000 esemplari. Solo l' annullamento dell' ordine di Garuda ( 50 aerei ) se confermato, vale da solo 2 volte e mezza i costi segnalati dall' articolo del Corriere.

Se veramente il taglio fosse del 20% sul lungo periodo la perdita sarebbe 100 miliardi, riva da mettere in seria difficoltà la bilancia commerciale degli USA. Ovviamente è presto per dirlo ma Boeing adesso deve trovare soluzioni davvero convincenti.
Prevedo ulteriori annullamenti e subito dopo la soluzione del problema un bell'aumento di ordini da Ryanair o altre low cost a seguito di cospiqui sconti di Boeing.
Ricordo ancora il maxi ordine di Ryanair dopo 11 Settembre....
 

OneShot

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Bellissima cronistoria, condita con fatti e dichiarazioni, apparsa sul NYT.
Assolutamente da leggere.

. .Boeing’s 737 Max: 1960s Design, 1990s Computing Power and Paper Manuals

Pilots start some new Boeing planes by turning a knob and flipping two switches.

The Boeing 737 Max, the newest passenger jet on the market, works differently. Pilots follow roughly the same seven steps used on the first 737 nearly 52 years ago: Shut off the cabin’s air-conditioning, redirect the air flow, switch on the engine, start the flow of fuel, revert the air flow, turn back on the air conditioning, and turn on a generator.

The 737 Max is a legacy of its past, built on decades-old systems, many that date back to the original version. The strategy, to keep updating the plane rather than starting from scratch, offered competitive advantages. Pilots were comfortable flying it, while airlines didn’t have to invest in costly new training for their pilots and mechanics. For Boeing, it was also faster and cheaper to redesign and recertify than starting anew.

But the strategy has now left the company in crisis, following two deadly crashes in less than five months. The Max stretched the 737 design, creating a patchwork plane that left pilots without some safety features that could be important in a crisis — ones that have been offered for years on other planes. It is the only modern Boeing jet without an electronic alert system that explains what is malfunctioning and how to resolve it. Instead pilots have to check a manual.

The Max also required makeshift solutions to keep the plane flying like its ancestors, workarounds that may have compromised safety. While the findings aren’t final, investigators suspect that one workaround, an anti-stall system designed to compensate for the larger engines, was central to the crash last month in Ethiopia and an earlier one in Indonesia.
The Max “ain’t your father’s Buick,” said Dennis Tajer, a spokesman for the American Airlines pilots’ union who has flown the 737 for a decade. He added that “it’s not lost on us that the foundation of this aircraft is from the ’60s.”
The Max, Boeing’s best-selling model, with more than 5,000 orders, is suddenly a reputational hazard. It could be weeks or months before regulators around the world lift their ban on the plane, after Boeing’s expected software fix was delayed. Southwest Airlines and American Airlines have canceled some flights through May because of the Max grounding.

The company has slowed production of the plane, putting pressure on its profits, and some buyers are reconsidering their orders. Shares of the company fell over 4 percent on Monday, and are down 11 percent since the Ethiopia crash.
“It was state of the art at the time, but that was 50 years ago,” said Rick Ludtke, a former Boeing engineer who helped design the Max’s cockpit. “It’s not a good airplane for the current environment.”

The 737 has long been a reliable aircraft, flying for decades with relatively few issues. Gordon Johndroe, a Boeing spokesman, defended the development of the Max, saying that airlines wanted an updated 737 over a new single-aisle plane and that pilots were involved in its design.

“Listening to pilots is an important aspect of our work. Their experienced input is front-and-center in our mind when we develop airplanes,” he said in a statement. “We share a common priority — safety — and we listen carefully to their feedback.” He added that American regulators approved the plane under the same standards they used with previous aircraft.
Boeing’s chief executive, Dennis Muilenburg, said in a statement on Friday that the crashes in Indonesia and Ethiopia appeared to have been caused by the Max’s new anti-stall system. “We have the responsibility to eliminate this risk, and we know how to do it,” he said.
At a factory near Seattle on Jan. 17, 1967, flight attendants christened the first Boeing 737, smashing champagne bottles over its wing. Boeing pitched the plane as a smaller alternative to its larger jets, earning it the nickname the “Baby Boeing.”

Early on, sales lagged Boeing’s biggest competitor, McDonnell Douglas. In 1972, Boeing had delivered just 14 of the jets, and it considered selling the program to a Japanese manufacturer, said Peter Morton, the 737 marketing manager in the early 1970s. “We had to decide if we were going to end it, or invest in it,” Mr. Morton said.

Ultimately, Boeing invested. The 737 eventually began to sell, bolstered by airline deregulation in 1978. Six years later, Boeing updated the 737 with its “classic” series, followed by the “next generation” in 1997, and the Max in 2017. Now nearly one in every three domestic flights in the United States is on a 737, more than any other line of aircraft.
Each of the three redesigns came with a new engine, updates to the cabin and other changes. But Boeing avoided overhauling the jet in order to appease airlines, according to current and former Boeing executives, pilots and engineers, some of whom spoke on the condition of anonymity because of the open investigations. Airlines wanted new 737s to match their predecessors so pilots could skip expensive training in flight simulators and easily transition to new jets.
Boeing’s strategy worked. The Federal Aviation Administration never required simulator training for pilots switching from one 737 to the next.

“Airlines don’t want Boeing to give them a fancy new product if it requires them to retrain their pilots,” said Matthew Menza, a former 737 Max test pilot for Boeing. “So you iterate off a design that’s 50 years old. The old adage is: If it’s not broke, don’t fix it.”
It did require engineering ingenuity, to ensure a decades-old jet handled mostly the same. In doing so, some of the jet’s one-time selling points became challenges.

For instance, in the early years of the 737, jet travel was rapidly expanding across the world. The plane’s low-slung frame was a benefit for airlines and airports in developing countries. Workers there could load bags by hand without a conveyor belt and maintain the engines without a lift, Mr. Morton said. In the decades that followed, the low frame repeatedly complicated efforts to fit bigger engines under the wing.

By 2011, Boeing executives were starting to question whether the 737 design had run its course. The company wanted to create an entirely new single-aisle jet. Then Boeing’s rival Airbus added a new fuel-efficient engine to its line of single-aisle planes, the A320, and Boeing quickly decided to update the jet again.
“We all rolled our eyes. The idea that, ‘Here we go. The 737 again,’” said Mr. Ludtke, the former 737 Max cockpit designer who spent 19 years at Boeing.

“Nobody was quite perhaps willing to say it was unsafe, but we really felt like the limits were being bumped up against,” he added.

Some engineers were frustrated they would have to again spend years updating the same jet, taking care to limit any changes, instead of starting fresh and incorporating significant technological advances, the current and former engineers and pilots said. The Max still has roughly the original layout of the cockpit and the hydraulic system of cables and pulleys to control the plane, which aren’t used in modern designs. The flight-control computers have roughly the processing power of 1990s home computers. A Boeing spokesman said the aircraft was designed with an appropriate level of technology to ensure safety.

When engineers did make changes, it sometimes created knock-on effects for how the plane handled, forcing Boeing to get creative. The company added a new system that moves plates on the wing in part to reduce stress on the plane from its added weight. Boeing recreated the decades-old physical gauges on digital screens.

As Boeing pushed its engineers to figure out how to accommodate bigger, more fuel-efficient engines, height was again an issue. Simply lengthening the landing gear to make the plane taller could have violated rules for exiting the plane in an emergency.
Instead, engineers were able to add just a few inches to the front landing gear and shift the engines farther forward on the wing. The engines fit, but the Max sat at a slightly uneven angle when parked.

While that design solved one problem, it created another. The larger size and new location of the engines gave the Max the tendency to tilt up during certain flight maneuvers, potentially to a dangerous angle.

To compensate, Boeing engineers created the automated anti-stall system, called MCAS, that pushed the jet’s nose down if it was lifting too high. The software was intended to operate in the background so that the Max flew just like its predecessor. Boeing didn’t mention the system in its training materials for the Max.

Boeing also designed the system to rely on a single sensor — a rarity in aviation, where redundancy is common. Several former Boeing engineers who were not directly involved in the system’s design said their colleagues most likely opted for such an approach since relying on two sensors could still create issues. If one of two sensors malfunctioned, the system could struggle to know which was right.

Airbus addressed this potential problem on some of its planes by installing three or more such sensors. Former Max engineers, including one who worked on the sensors, said adding a third sensor to the Max was a nonstarter. Previous 737s, they said, had used two and managers wanted to limit changes.
“They wanted to A, save money and B, to minimize the certification and flight-test costs,” said Mike Renzelmann, an engineer who worked on the Max’s flight controls. “Any changes are going to require recertification.” Mr. Renzelmann was not involved in discussions about the sensors.

The Max also lacked more modern safety features.

Most new Boeing jets have electronic systems that take pilots through their preflight checklists, ensuring they don’t skip a step and potentially miss a malfunctioning part. On the Max, pilots still complete those checklists manually in a book.

A second electronic system found on other Boeing jets also alerts pilots to unusual or hazardous situations during flight and lays out recommended steps to resolve them.

On 737s, a light typically indicates the problem and pilots have to flip through their paper manuals to find next steps. In the doomed Indonesia flight, as the Lion Air pilots struggled with MCAS for control, the pilots consulted the manual moments before the jet plummeted into the Java Sea, killing all 189 people aboard.

“Meanwhile, I’m flying the jet,” said Mr. Tajer, the American Airlines 737 captain. “Versus, pop, it’s on your screen. It tells you, This is the problem and here’s the checklist that’s recommended.”

Boeing decided against adding it to the Max because it could have prompted regulators to require new pilot training, according to two former Boeing employees involved in the decision.

The Max also runs on a complex web of cables and pulleys that, when pilots pull back on the controls, transfer that movement to the tail. By comparison, Airbus jets and Boeing’s more modern aircraft, such as the 777 and 787, are “fly-by-wire,” meaning pilots’ movement of the flight controls is fed to a computer that directs the plane. The design allows for far more automation, including systems that prevent the jet from entering dangerous situations, such as flying too fast or too low. Some 737 pilots said they preferred the cable-and-pulley system to fly-by-wire because they believed it gave them more control.

In the recent crashes, investigators believe the MCAS malfunctioned and moved a tail flap called the stabilizer, tilting the plane toward the ground. On the doomed Ethiopian Airlines flight, the pilots tried to combat the system by cutting power to the stabilizer’s motor, according to the preliminary crash report.

Once the power was cut, the pilots tried to regain control manually by turning a wheel next to their seat. The 737 is the last modern Boeing jet that uses a manual wheel as its backup system. But Boeing has long known that turning the wheel is difficult at high speeds, and may have required two pilots to work together.

In the final moments of the Ethiopian Airlines flight, the first officer said the method wasn’t working, according to the preliminary crash report. About 1 minute and 49 seconds later, the plane crashed, killing 157 people.
https://www.nytimes.com/2019/04/08/business/boeing-737-max-.html
 

Volvic

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Bellissima cronistoria, condita con fatti e dichiarazioni, apparsa sul NYT.
Assolutamente da leggere.

https://www.nytimes.com/2019/04/08/business/boeing-737-max-.html
He added that American regulators approved the plane under the same standards they used with previous aircraft.
Grazie per il post.
La frase, penso e spero di circostanza, potrebbe leggersi in due modi ben distinti, molto ben distinti.

Da quanto emerge, anche in caso di assoluto non coinvolgimento del MCAS, Boeing ha esagerato a rilavorare così tanto lo stesso aereomobile. Produci un game changer come il 787, dimostri che quando VUOI puoi fare cose incredibile, e poi allunghi qui, sposti lì, lasci cavi e carrucole e volantini sperando nei muscoli), eviti di implementare nuove interfaccie per poter allettare con costi minori di transizione.

Ritengo che debbano ricevere l'unico messaggio nell'unico posto che sembrano comprendere e di cui sembrano preoccuparti al momento. Pecuniario. Dovevano ricertificare se mettevano tre sonde ?
E quindi ? Ricertificavano.
Ho una sonda ? forse funziona, forse
Ho due sonde ? sono certo che funzionano ma se una si guasta lo capisco ma sò solo che non posso essere certo del valore (lancio della monetina)
Ho tre sonde ? sono certo che funzionano e se una si guasta ne vengo informato e posso decidere su quale dei dati fare più affidamento
 

Nickee

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Dal report si evince che tutte le azioni che hanno portato alla morte di più di 300 persone sono in gran parte attribuibili al desiderio di Boeing di rinnovare il proprio 737 spendendo il meno possibile e facendo spendere il meno possibile alle compagnie aeree.

Come scritto sopra, probabilmente sarebbe bastato che il sistema anti stallo leggesse i dati di volo da 3 sonde piuttosto che da una, per evitare le due tragedie. Peccato che ciò avrebbe comportato un aumento dei costi di sviluppo e dei tempi di commercializzazione.

Se tale atteggiamento ha permesso a Boeing di raccogliere ben 5000 ordini probabilmente hanno fatto bene, peccato sarebbe stata solo questione di tempo per far sì che le magagne venissero fuori.

Terribile.

Inviato dal mio CLT-L09 utilizzando Tapatalk
 

Volvic

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Dal report si evince che tutte le azioni che hanno portato alla morte di più di 300 persone sono in gran parte attribuibili al desiderio di Boeing di rinnovare il proprio 737 spendendo il meno possibile e facendo spendere il meno possibile alle compagnie aeree.
Chi compra spendendo 120 non ha poi tutto questo interesse a sapere che 100 vanno al produttore e 20 in spese collaterali oppure tutti e 120 al produttore
Chi produce ha invece MOLTO interesse a che gli arrivino tutti i 120 spesi (o la maggior parte).


Se tale atteggiamento ha permesso a Boeing di raccogliere ben 5000 ordini probabilmente hanno fatto bene
No, ha fatto bene solo ai bilanci e causato oltre 300 morti (non intenzionalmente ma con il classico approccio rischi/benefici).
Installavano, cambiavano, ricertificavano ed evitavano almeno 300 morti; al posto dei 5000 ordini magari ne avrebbero avuti solo 4000, e quindi ?
Se domani l'impatto finanziario di questa faccenda alla fine sarà a loro vantaggio, che lezione avranno imparato ? Che la vendita di 1000 aerei in più vale un paio di incidenti catastrofici e la vita di oltre 300 persone ?

Ripeto, Being quando VUOLE si è dimostrata in grado di creare game changers, come il 787. Qui non ha semplicemente voluto.
 

Nickee

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Chi compra spendendo 120 non ha poi tutto questo interesse a sapere che 100 vanno al produttore e 20 in spese collaterali oppure tutti e 120 al produttore
Chi produce ha invece MOLTO interesse a che gli arrivino tutti i 120 spesi (o la maggior parte).



No, ha fatto bene solo ai bilanci e causato oltre 300 morti (non intenzionalmente ma con il classico approccio rischi/benefici).
Installavano, cambiavano, ricertificavano ed evitavano almeno 300 morti; al posto dei 5000 ordini magari ne avrebbero avuti solo 4000, e quindi ?
Se domani l'impatto finanziario di questa faccenda alla fine sarà a loro vantaggio, che lezione avranno imparato ? Che la vendita di 1000 aerei in più vale un paio di incidenti catastrofici e la vita di oltre 300 persone ?

Ripeto, Being quando VUOLE si è dimostrata in grado di creare game changers, come il 787. Qui non ha semplicemente voluto.
Ovviamente il messaggio non era un plauso a boeing ma piuttosto un ulteriore accusa (per quanto possa valere la mia opinione)

Inviato dal mio CLT-L09 utilizzando Tapatalk
 

Simme71

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magick

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Sembra sempre più assodato che il software abbia funzionato esattamente per il motivo per cui è stato creato. A questo punto mi chiedo se le modifiche che Boeing sta apportando siano necessarie e non sia più opportuno lavorare sulle sonde e la loro ridondanza.
 

Farfallina

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Sembra sempre più assodato che il software abbia funzionato esattamente per il motivo per cui è stato creato. A questo punto mi chiedo se le modifiche che Boeing sta apportando siano necessarie e non sia più opportuno lavorare sulle sonde e la loro ridondanza.
Immagino che valutino anche l'intervento sulle sonde e ridondanza, il punto è che se riescono a modificare il software è molto più semplice per loro.

Leggevo che Trump ha ventilato pesanti sanzioni per Airbus.
 

13900

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Leggevo che Trump ha ventilato pesanti sanzioni per Airbus.
Sono cose leggermente diverse. Gli USA stanno ventilando sanzioni ai danni dell'UE per via di una sentenza del WTO che ha deciso che, per 380 e 350, Airbus ha ricevuto sussidi da parte dei paesi UE. Mi piacerebbe però sapere cosa pensa lo stesso WTO degli aiuti governativi americani, nonché di quelli di Washington e South Carolina, a favore di Boeing. Inoltre le Japanese Heavies hanno anch'esse ricevuto sussidi per il loro "pezzo" del programma 787... #ilpiupulitochalarogna
 

OneShot

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Sembra sempre più assodato che il software abbia funzionato esattamente per il motivo per cui è stato creato. A questo punto mi chiedo se le modifiche che Boeing sta apportando siano necessarie e non sia più opportuno lavorare sulle sonde e la loro ridondanza.
Le modifiche proposte sono già un ottimo compromesso per riportare il MAX in volo il più in fretta possibile: doppia sonda come "source" per il mcas con indicazione al flight crew di discordanza, rendere i due optional su AOA e disagree alert di serie, quindi ne verrebbe fuori una giusta pezza.
Per le tre sonde, invece, servirebbero delle modifiche molto più laboriose, modificando più di un software, hardware e sistemi vari. Se viene reso chiaro ai piloti il problema legato a pitch, aoa e tutto quello che verrà fuori dai due incidenti, il 737 avrà lunga vita.
Ricordatevi che no è stato l'unico aeroplano con problemi di manovrabilità: l'MD11 soffriva molto il crosswind e richiedeva precisione chirurgica in determinati avvicinamenti. Eppure era (è) una macchina fantastica.
Il Trident della BEA che si schiantò dopo il decollo per un azionamento della leva della droop (così erano stati battezzati i leading edge slats) al posto dei flaps, ecc ecc...
 

magick

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Le modifiche proposte sono già un ottimo compromesso per riportare il MAX in volo il più in fretta possibile: doppia sonda come "source" per il mcas con indicazione al flight crew di discordanza, rendere i due optional su AOA e disagree alert di serie, quindi ne verrebbe fuori una giusta pezza.
Per le tre sonde, invece, servirebbero delle modifiche molto più laboriose, modificando più di un software, hardware e sistemi vari. Se viene reso chiaro ai piloti il problema legato a pitch, aoa e tutto quello che verrà fuori dai due incidenti, il 737 avrà lunga vita.
Ricordatevi che no è stato l'unico aeroplano con problemi di manovrabilità: l'MD11 soffriva molto il crosswind e richiedeva precisione chirurgica in determinati avvicinamenti. Eppure era (è) una macchina fantastica.
Il Trident della BEA che si schiantò dopo il decollo per un azionamento della leva della droop (così erano stati battezzati i leading edge slats) al posto dei flaps, ecc ecc...
Grazie per la risposta esaustiva. In realtà avevo capito che uno degli optional riguardassero la possibilità di avere la terza sonda, da qui il mio commento.
 

East End Ave

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su e giu' sull'atlantico...
Le modifiche proposte sono già un ottimo compromesso per riportare il MAX in volo il più in fretta possibile: doppia sonda come "source" per il mcas con indicazione al flight crew di discordanza, rendere i due optional su AOA e disagree alert di serie, quindi ne verrebbe fuori una giusta pezza.
Per le tre sonde, invece, servirebbero delle modifiche molto più laboriose, modificando più di un software, hardware e sistemi vari. Se viene reso chiaro ai piloti il problema legato a pitch, aoa e tutto quello che verrà fuori dai due incidenti, il 737 avrà lunga vita.
Ricordatevi che no è stato l'unico aeroplano con problemi di manovrabilità: l'MD11 soffriva molto il crosswind e richiedeva precisione chirurgica in determinati avvicinamenti. Eppure era (è) una macchina fantastica.
Il Trident della BEA che si schiantò dopo il decollo per un azionamento della leva della droop (così erano stati battezzati i leading edge slats) al posto dei flaps, ecc ecc...
GRAZIE OneShot! La tua presenza sul forum, al pari di quella di altri professionisti di calibro, penso a MDSuper80-Tienneti-LICA...., permette il coinvolgimento di noi "umani" in tematiche altrimenti incomprensibili, permettendo comprensione e confronto; il pane di un forum di eccellenza.
 

Fewwy

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Changes to Flight Software on 737 Max Escaped F.A.A. Scrutiny
https://www.nytimes.com/2019/04/11/business/boeing-faa-mcas.html?fbclid=IwAR1mrdNhOUC8FyOANatBCUtvZ7uL36FzJjGUvMjzXVO9VvBg9mqJk1KHpKE
By Jack Nicas, David Gelles and James Glanz

While it was designing its newest jet, Boeing decided to quadruple the power of an automated system that could push down the plane’s nose — a movement that made it difficult for the pilots on two doomed flights to regain control.

The company also expanded the use of the software to activate in more situations, as it did erroneously in the two deadly crashes involving the plane, the 737 Max, in recent months.

None of those changes to the anti-stall system, known as MCAS, were fully examined by the Federal Aviation Administration.

Although officials were aware of the changes, the modifications didn’t require a new safety review, according to three people with knowledge of the process. It wasn’t necessary under F.A.A. rules since the changes didn’t affect what the agency considers an especially critical or risky phase of flight.

A new review would have required F.A.A. officials to take a closer look at the system’s effect on the overall safety of the plane, as well as to consider the potential consequences of a malfunction. Instead, the agency relied on an earlier assessment of the system, which was less powerful and activated in more limited circumstances.

Ever since the crashes — in Indonesia last October and Ethiopia last month — investigators, prosecutors and lawmakers have scrutinized what went wrong, from the design and certification to the training and response.

In both crashes, the authorities suspect that faulty sensor data triggered the anti-stall system, revealing a single point of failure on the plane. Pilots weren’t informed about the system until after the Lion Air crash in Indonesia, and even then, Boeing didn’t fully explain or understand the risks. The F.A.A. outsourced much of the certification to Boeing employees, creating a cozy relationship between the company and its regulator.

But the omission by the F.A.A. exposes an embedded weakness in the approval process, providing new information about the failings that most likely contributed to the crashes in Indonesia and Ethiopia.

The F.A.A. is supposed to be the gold standard in global aviation regulation, with the toughest and most stringent rules for certifying planes. But the miscalculation over MCAS undermines the government’s oversight, raising further concerns about its ability to push back against the industry or root out design flaws.

While it is unclear which officials were involved in the review of the anti-stall system, they followed a set of bureaucratic procedures, rather than taking a proactive approach. The result is that officials didn’t fully understand the risks of the more robust anti-stall system, which could cause a crash in less than a minute.

“The more we know, the more we realize what we don’t know,” said John Cox, an aviation safety consultant and former 737 pilot.

The F.A.A. defended its certification process, saying it has consistently produced safe aircraft. An F.A.A. spokesman said agency employees collectively spent more than 110,000 hours reviewing the Max, including 297 test flights.

The spokesman said F.A.A. employees were following agency rules when they didn’t review the change. “The change to MCAS didn’t trigger an additional safety assessment because it did not affect the most critical phase of flight, considered to be higher cruise speeds,” an agency spokesman said. “At lower speeds, greater control movements are often necessary.”

A spokesman for Boeing said, “The F.A.A. considered the final configuration and operating parameters of MCAS during Max certification, and concluded that it met all certification and regulatory requirements.”

Some of the details of the evolving design of MCAS were earlier reported by The Seattle Times.

MCAS was created to help make the 737 Max handle like its predecessors, part of Boeing’s strategy to get the plane done more quickly and cheaply.

The system was initially designed to engage only in rare circumstances, namely high-speed maneuvers, in order to make the plane handle more smoothly and predictably for pilots used to flying older 737s, according to two former Boeing employees who spoke on the condition of anonymity because of the open investigations.

For those situations, MCAS was limited to moving the stabilizer — the part of the plane that changes the vertical direction of the jet — about 0.6 degrees in about 10 seconds.

It was around that design stage that the F.A.A. reviewed the initial MCAS design. The planes hadn’t yet gone through their first test flights.

After the test flights began in early 2016, Boeing pilots found that just before a stall at various speeds, the Max handled less predictably than they wanted. So they suggested using MCAS for those scenarios, too, according to one former employee with direct knowledge of the conversations.

But the system needed more power to work in a broader range of situations.

At higher speeds, flight controls are more sensitive and less movement is needed to steer the plane. Consider the effect of turning a car’s steering wheel at 70 miles an hour versus 30 miles an hour.

To prevent stalls at lower speeds, Boeing engineers decided that MCAS needed to move the stabilizer faster and by a larger amount. So Boeing engineers quadrupled the amount it could move the stabilizer in one cycle, to 2.5 degrees in less than 10 seconds.

“That’s a huge difference,” said Dennis Tajer, a spokesman for the American Airlines pilots’ union who has flown 737s for a decade. “That’s the difference between controlled flight or not.”

Speed was a defining characteristic for the F.A.A. The agency’s rules require an additional review only if the changes affect how the plane operates in riskier phases of flight: at high speeds and altitudes. Because the changes to the anti-stall system affected how it operated at lower speeds and altitudes, F.A.A. employees didn’t need to take a closer look at them.

The overall system represented a major departure from Boeing’s design philosophy. Boeing has traditionally favored giving pilots control over their planes, rather than automated flight systems.

“In creating MCAS, they violated a longstanding principle at Boeing to always have pilots ultimately in control of the aircraft,” said Chesley B. Sullenberger III, the retired pilot who landed a jet in the Hudson River. “In mitigating one risk, they created another, greater risk.”

The missed risks, by the F.A.A. and Boeing, flowed to other decisions. A deep explanation of the system wasn’t included in the plane manual. The F.A.A. didn’t require training on it. Even Boeing test pilots weren’t fully briefed on MCAS.

“Therein lies the issue with the design change: Those pitch rates were never articulated to us,” said one test pilot, Matthew Menza.

Mr. Menza said he looked at documentation he still had and did not see mention of the rate of movement on MCAS. “So they certainly didn’t mention anything about pitch rates to us,” he said, “and I certainly would’ve loved to have known.”

The system’s increased power was also compounded by its design: The software engaged repeatedly if the sensor suggested it was necessary to avoid a stall. In the Lion Air crash, data showed that the pilots, who weren’t aware of MCAS, fought for control of the plane, as it pushed the nose back down each time they pulled it up.

Few truly understood just how powerful the system would prove. It wasn’t fully disclosed until after the Lion Air disaster, killing all 189 people on board. On the Ethiopian Airlines flight, the pilots struggled to regain control after MCAS engaged at least three times.

Last month, during flight simulations recreating the problems with the Lion Air flight, American pilots were surprised at how strong MCAS was. They essentially had less than 40 seconds to manually override a system malfunction before a crash.

Updates to the software by Boeing, which the F.A.A. will have to approve, will address some of the concerns with the anti-stall system. The changes will limit the system to engaging just once in most cases. And they will prevent MCAS from pushing the plane’s nose down more than a pilot could counteract by pulling up on the controls.

Boeing had hoped to deliver the software fix to the F.A.A. by now but it was delayed by several weeks. As a result, the grounding of the jet is expected to drag on. Southwest Airlines and American Airlines have already canceled some flights through May.
 

giova0

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Changes to Flight Software on 737 Max Escaped F.A.A. Scrutiny
[...] Although officials were aware of the changes, the modifications didn’t require a new safety review, according to three people with knowledge of the process. It wasn’t necessary under F.A.A. rules since the changes didn’t affect what the agency considers an especially critical or risky phase of flight.[...]
Mi sembra che siamo di fronte a regole chiare e di buon senso, ma che vengono aggirate . Se per degli ispettori terzi, l'introduzione di un sistema in grado di influire così pesantemente nella dinamica del volo non è una modifica critica, vien da chiedersi cosa lo sia. E soprattutto, viene da chiedersi chi siano questi tre personaggi "con conoscenza del processo" e quanto effettivamente siano terzi rispetto agli interessi di chi quell'aereo lo produce.