Posted on 10/25/2019 5:58:49 AM PDT by Yo-Yo
Investigators said faults by Boeing, Lion Air and pilots caused the crash.
Five months after the disaster in October last year, an Ethiopian Airlines plane crashed, killing all 157 people on board, which led to the grounding of the entire 737 Max fleet.
Faults with the plane's design have been linked to both crashes.
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What does the report say?
The 353-page report found the jet should have been grounded before departing on the fatal flight because of an earlier cockpit issue.
However, because the issue was not recorded properly the plane was allowed to take off without the fault being fixed, it said.
Further, a crucial sensor - which had been bought from a repair shop in Florida - had not been properly tested, the report found.
That sensor fed information to the plane's Manoeuvring Characteristics Augmentation System - or MCAS. That software, which is designed to help prevent the 737 Max from stalling, has been a focus for investigators trying to find the cause of both the Lion Air and Ethiopian Airlines crashes.
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Further, the report found that the first officer, who had performed poorly in training, struggled to run through a list of procedures that he should have had memorised.
He was flying the plane just before it entered into the fatal dive, but the report said the captain had not briefed him properly when he handed over the controls as they struggled to keep the plane in the air.
The report also found that 31 pages were missing from the plane's maintenance log.
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(Excerpt) Read more at bbc.com ...
"If one of the nine hadn't occurred, maybe the accident wouldn't have occurred."
Also known as the accident chain. Break any one link in the chain, and the accident probably would not have occurred.
Eight of the nine factors were outside of Boeing's control.
Questionable parts sourcing, poor or incomplete maintenance, poor maintenance records, poor First Officer performance (noted in past evaluations), etc.
However, Boeing's poor execution of MCAS by not cross referencing both AOA sensors is a major contributor that had it been executed properly, would have broken the accident chain.
If Top-Gun level pilots were needed to fly the Max (whereas crappy pilots could fly all of the other 737s that were built), then that should have been made that clear to the airlines...rather than making them and their customers find out the hard way.
I think these types of articles completely miss the more important facts and concentrate on the “me too” bandwagon type of reporting, going to the single sensor as a root cause. It wasn’t the root cause.
Dual sensors were a part the final design, but the primary problem was that the MCAS system was never certified to allow moving the elevators as far and as fast as they did. Even with a single sensor, if MCAS was held to the 1.6 degree of movement as it was certified, instead of the 10.6 degrees of movement as it was produced, there would have been no problem.
For the impulsive and feeble minded jumping to a wrong conclusion, the difference may be 10x but that wasn’t a reading of the specifications improperly, it was intentional.
This kind of stuff always reminds me of Miss Brown mu grade school teacher. You NEVER got a pass on ANYTHING! That’s unheard of in today’s schools…by now, accountability and honesty are things of the past!!
For kids now days, mediocre is ‘good enough’. That means we end up with a society of so-called ‘professionals’ running things who just slid through their education. Facts are not hard and fast … ‘truth’ is totally relative. We’re so screwed!
Eight of the nine factors were outside of Boeing’s control.
Also known as the accident chain. Break any one link in the chain, and the accident probably would not have occurred.
Same thing with the Shuttle Challenger explosion.
The same aircraft experienced the same runaway stabilizer trim event due the faulty AOA sensor and landed safely. The only difference was the knowledge, training, and experience of the check pilot who shut down the system that was pushing the nose over and reduced power to regain control. If this had been properly reported and the aircraft grounded until a repair was made the crash on the next day could have been avoided. Even with redundant sensors there would still be a finite probability that both would fail or something else would trigger the runaway stabilizer trim event. Even when both engines failed over the Manhattan Bay Sully Sullenberg fell back on his skills and instincts to pilot the plane and beat the odds.
Please provide a link.
Also, the MCAS does not move the elevators...it moves the horizontal stabilizer.
The motor that runs the horizontal stabilizer had 2 speeds. When the flaps are down, the motor runs at high speed. When the flaps are up, the motor normally runs at low speed. MCAS is designed to command the motor to run at high speed when the flaps are up.
“repair shop in Florida”
Florida-man again. If
He was flying the plane just before it entered into the fatal dive, but the report said the captain had not briefed him properly when he handed over the controls as they struggled to keep the plane in the air.
I'm not sure where you draw the line at "Top-Gun level pilot skills," but hopefully that doesn't include successfully learning what you are taught in pilot training.
I’m questioning your username at this point. The elevators are the moveable part of the horizontal stabilizer. The horizontal stabilizer is generally fixed. There are some aircraft where the entire horizontal stabilizer rotates to give elevator control, but that is rare.
I meant to cc: ping you to my #11.
Even the illustrations posted above shows the entire 737 horizontal stabilizer moves.
On the Boeing 737, as on most modern jets, pitch trim moves the entire horizontal stabilizer, not just a trim tab on the elevator.
Are you saying ALL the hundreds(thousands?) of successful flights of the Boeing 737 Max were because of “Top-Gun” level piloting?
The report seems to indicate the piloting was SUB-STANDARD at best.
I think the lesson is stay away from lousy airlines in 3rd world nations.
I stand corrected.
Please provide a link.
Here's an interesting read on the history of MCAS development on the 737MAX: https://www.seattletimes.com/seattle-news/times-watchdog/the-inside-story-of-mcas-how-boeings-737-max-system-gained-power-and-lost-safeguards/
A couple of snippets from the article:
When Boeing was ready to certify the 737 MAX, it laid out its plan for MCAS in documents for the FAA.
Under the proposal, MCAS would trigger in narrow circumstances. It was designed “to address potentially unacceptable nose-up pitching moment at high angles of attack at high airspeeds,” Boeing told the FAA in a proprietary System Safety Assessment reviewed by The Times.
In a separate presentation made for foreign safety regulators that was reviewed by The Times, Boeing described MCAS as providing “a nose down command to oppose the pitch up. Command is limited to 0.6 degrees from trimmed position.”Two people involved in the initial design plans for MCAS said the goal was to limit the system’s effect, giving it as little authority as possible. That 0.6-degree limit was embedded in the company’s system safety review for the FAA.
And later in the article:
About a third of the way through flight testing in 2016, as first reported by The Seattle Times in March, Boeing made substantial changes to MCAS.
The flight-test pilots had found another problem: The same lack of smooth stick forces was also occurring in certain low-speed flight conditions. To cover that issue too, engineers decided to expand the scope and power of MCAS.
Because at low speed a control surface must be deflected more to have the same effect, engineers increased the power of the system at low speed from 0.6 degrees of stabilizer nose-down deflection to 2.5 degrees each time it was activated.
On the stabilizer, maximum nose down is about 4.7 degrees away from level flight. So with the new increased authority to move the stabilizer, just a couple of iterations of the system could push it to that maximum.
Because there are no excessive G-forces at low speed, the engineers removed the G-force factor as a trigger. But that meant MCAS was now activated by a single angle-of-attack sensor.
One of the people familiar with MCAS’s evolution said the system designers didn’t see any need to add an additional sensor or redundancy because the hazard assessment had determined that an MCAS failure in normal flight would only qualify in the “major” category for which the single sensor is the norm.
“It wasn’t like it was there to cover some safety or certification requirement,” the person said. “The trigger isn’t a safeguard. It tells (the system) when to operate.”
While the changes were dramatic, Boeing did not submit documentation of the revised system safety assessment to the FAA.
So the numbers may be off a bit, but Boeing did expand the scope and authority of MCAS but did not update its certification documentation to the FAA, according to this Seattle Times article.
Actually, you were half correct. The 737 has a tailplane, which sometimes is incorrectly called a horizontal stabilizer. It also has an elevator. The tailplane provides pitch trim, but the elevator provides pitch control for maneuvering.
flr
“I think the lesson is stay away from lousy airlines in 3rd world nations.”
I think it’s unfortunate that all of the planes didn’t use dual redundant angle-of-attack sensor. That was originally an option when the planes were purchased.
I think there’s room for improvement to make the planes more idiot proof.
But Boeing is being crucified for what should be the normal process of identifying weaknesses and making improvements, something that’s done all the time.
I’ll bet every plane in the sky has had improvements made. Also there’s the matter of maintenance. Poor maintenance is not Boeing’s fault unless they’re doing the maintenance. Poor parts supplied by vendors other than Boeing are not Boeing’s fault.
The truth will slowly emerge.
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