Lion Air

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Anaxagoras
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Re: Lion Air

Post by Anaxagoras » Mon Apr 08, 2019 1:02 pm

ed wrote:
Mon Apr 08, 2019 10:50 am
3- What makes the problem occur? Why does it on happen every time the plane flys?
See my post above with the graphic. Read the article. The caveat is that these are still preliminary findings. But it seems that the way the plane was designed is faulty. There's a kind of automatic system that was supposed to prevent the plane from stalling but has resulted in the plane crashing twice now because they didn't fully recognize how it could malfunction.
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ed
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Re: Lion Air

Post by ed » Mon Apr 08, 2019 1:04 pm

Anaxagoras wrote:
Mon Apr 08, 2019 1:02 pm
ed wrote:
Mon Apr 08, 2019 10:50 am
3- What makes the problem occur? Why does it on happen every time the plane flys?
See my post above with the graphic. Read the article. The caveat is that these are still preliminary findings. But it seems that the way the plane was designed is faulty. There's a kind of automatic system that was supposed to prevent the plane from stalling but has resulted in the plane crashing twice now because they didn't fully recognize how it could malfunction.
I get all that but why not every time?
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Anaxagoras
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Re: Lion Air

Post by Anaxagoras » Mon Apr 08, 2019 1:08 pm

Because I think it only happens when the angle of attack sensor is faulty. Maybe a bird hit it.
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ed
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Re: Lion Air

Post by ed » Mon Apr 08, 2019 1:14 pm

How much information does a commercial jet generate potentially per second.

Like the sensor. the outpout + an indication that it is working, what is that, two bytes and a bit?
So what is everything? a gig? no, too much.

Why dont they just transmit the whole fucking mess continuously? I have suggested this before and I was ignored.

ETA: And people have DIED as a result :x :x :x
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sparks
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Re: Lion Air

Post by sparks » Mon Apr 08, 2019 2:23 pm

Some airlines to upload in real time IIRC.

Not ours. Because they don't care about The Childrenz(tm).
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ed
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Re: Lion Air

Post by ed » Mon Apr 08, 2019 2:25 pm

Knew it. Probably a Trump mandate.

It should be required. Probably pretty easy. I bet Rob could impliment it in a few minutes.
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Anaxagoras
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Re: Lion Air

Post by Anaxagoras » Mon Apr 08, 2019 2:53 pm

I think it is just a little doohickey like this:

Image

A little blade on a spindle. Rotates according to the airflow. I don't think they have said why it wasn't working properly, but the consensus seems to be that it wasn't. So it was telling the flight control computer that the angle of attack was higher than it actually was in reality, causing the MCAS to automatically trim the rear stabs down, causing the nose of the aircraft to point down.

https://nationalpost.com/news/heres-the ... s-grounded
The 737 MAX 8 has heavier and more fuel-efficient engines than prior editions of the 737, a change which causes the aircraft to pitch upwards ever-so-slightly after takeoff.

Rather than instructing airlines to warn their pilots of this quirk, Boeing simply equipped the MAX 8 with MCAS, a program that would automatically tilt the nose downwards to compensate.

In normal circumstances, the system is not a problem, but it only takes a minor maintenance error to turn MCAS into a deadly liability.

In the case of Lion Air Flight 610, the 737 MAX 8 had a faulty “angle of attack sensor”; a small blade sticking out of the cockpit that records the angle of the aircraft in flight.

The sensor was wrongly telling the MAX 8’s flight computers that the aircraft was climbing much more sharply than it was. As a result, pilots were left wrestling with an aircraft that was repeatedly plunging itself towards the ground for no reason. A pilot can counteract the dive by pulling up on the control column, but MCAS will kick in again after only 10 seconds and once again tilt the plane downwards.

“If this is left unchecked (it) can lead to a potential nose heavy situation where it becomes almost impossible to manually raise the nose,” reads a November assessment of the Lion Air crash by Akan Bassey, a commercial pilot and blogger.

Indeed, the final minutes of Lion Air Flight 610 show the plane veering crazily up and down as the pilot fought with MCAS for control of the aircraft.

“The airplane tends to oscillate in this conflict between the software and the pilot,” Garneau, himself an experienced airman, said Wednesday.

Ultimately, the Lion Air 737 pitched itself forward 26 times before pilots ultimately lost control.

Adding to the confusion were stall warnings, in-cockpit alerts and faulty instrument readings, making it likely that the Lion Air pilots didn’t even know what was happening.

There is a series of complex steps that the pilots could have taken to override the MCAS system, but as the New York Times wrote in an analysis “these steps were not in the manual, and the pilots had not been trained in them.”

A Boeing official quoted by the Wall Street Journal said this was done due to fears of “inundating average pilots with too much information.”

However, while the manual may not contain MCAS-specific directions, a recent Boeing statement wrote that their manual “already outlines an existing procedure to safely handle the unlikely event of erroneous data coming from an angle of attack (AOA) sensor.”

“The pilot will always be able to override the flight control law using electric trim or manual trim,” it read.

Part of the relative mystery on MCAS is because it isn’t even supposed to be noticed by pilots, as it’s designed only to kick in during a potential emergency.

The program is a fail-safe designed to save the aircraft if it’s pitching too sharply, potentially putting it into a “stall”; a situation in which there is no longer enough air flowing over the wings to generate lift. As Boeing wrote in a recent statement, “MCAS does not control the airplane in normal flight; it improves the behavior of the airplane in a non-normal part of the operating envelope.”

Preliminary data from the crash of Ethiopian Airlines Flight 302 shows the same doomed trajectory. “It became clear — to all parties, actually — that the track of the Ethiopian Airlines flight was very close and behaved very similarly to the Lion Air flight,” Daniel Elwell, acting administrator of the Federal Aviation Administration, said in a briefing this week.
But see my previous post about how it may become impossible to manually fix the trim under certain conditions. This has recently been shown in a flight simulator.
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Rob Lister
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Re: Lion Air

Post by Rob Lister » Mon Apr 08, 2019 3:28 pm

Anaxagoras wrote:
Mon Apr 08, 2019 8:01 am
Here's that youtube channel. It's not clear exactly which video he's talking about:


thank you. you're welcome.