737 Max

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Fly Tupulew and You survive ... :)

Reply to
Leo Baumann
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"Without regard to airspeed".

I never had any difficulty with it.

Sylvia.

Reply to
Sylvia Else

About pilot training, in this case the co-pilot only had 200 flight hours. There are co-pilots with lesser flight hours. Hopefully they are paired with an experienced captain with a few thousand hours (not just 500-1000 hours).

The co-pilot is expected to safely land LONE the airliner if e.g. if the experienced captain gets a heart attack. With 100 hours ...

Reply to
upsidedown

The problem with e.g. AF447, Lion Air and possibly this case the faulty sensors feed faulty information into any automatic control system, that then act erratically, which the pilot doesn't understand.

For mission critical automation system, there should be at least three independent sensors, so that the automation system can vote between these sensors, i.e. get at least two matching results, before using the inputs for control. Preferably the sensors should use different working principles and preferably made by different companies.

Before large scale automation, typically only two (identical) sensors were used, In the best case the system could warn the pilots that the sensors disagree and it was up to the pilot to guess which sensor to believe and feeding it e.g. to the autopilot. Unfortunately in many crashes, the wrong (faulty) sensor was selected. Compare this to shutting down the only working engine, when one engine has problems.

With at least tree sensors, the automation has at least some means to know which signal to believe.

Reply to
upsidedown

That was the Comet 1.

Variants of the Comet 4 were flying until 2011, for bizarre reasons.

Reply to
Tom Gardner

That happens to me every week, or more - and the frequency is rising.

The last time was last night at ~6:30pm, as I was turning into a side road. I jammed on my breaks, of course, which caused the perp to look startled then sheepish as she realised what she had done.

Frequently mobile phones and headphones are in evidence, but not last night.

Autonomous cars that can't behave appropriately are not fit for purpose.

Reply to
Tom Gardner

Given the poster, is that a surprise?

Reply to
Tom Gardner

The problem was the square windows, in which the breakup started from the window edges due to metal fatigue.

That must be the Nimrod variant.

The Comet had to be removed from passenger service before the end of century due the tightening noise rules.

I hated the red winged BEA Comets departing. The noise was so intense that it was impossible to talk to an other person, when the Comet was in sight at 1000 m altitude. No such problems with current low noise planes like B787 or A350.

Reply to
upsidedown

Why not?

Anyway, I was in my backyard when I heard a "whoosh"ing gyrating sound above, and looked up to see a large bird wadded up and spiraling down toward me like a maple leaf. A spin! It landed about 15 feet away, behind a dirt mound, so I couldn't see the touchdown. I walked over and peeked over the mound, expecting a dead bird, and saw the hawk just standing there looking back at me. After a moment, it flew off.

I've twice seen ravens roll then glide inverted for several seconds, then roll back upright and continue on.

Reply to
Bonk

Yup.

I remember watching one take off underneath me.

One also took off while an acquaintance was on finals, and the wing vortex inverted his plane. No injuries, but 5 aircraft were written off :)

Reply to
Tom Gardner

The interesting thing with the Lion Air was that it flew the previous leg with the same sensor fault but a different pilot who did know how to disable MCAS and turn the faulty AOA sensor off. They took about a dozen goes before they twigged that there was a system fault though. It is described in the precis of the accident report here:

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The crashing flight crew tried 21 times by which time it hit the deck. So in a sense you could call it a human error in not disabling an automatic "safety" system that had gone rogue quickly enough.

Interesting that the problem only arose when the flaps were retracted so extending flaps again and more power might have also saved the plane.

It took about a month before they issued the initial report on the flight recorders last time. Lets hope that if it is the *same* fault that they can do it a bit quicker this time (and if it is another independent critical fault then that is probably worse).

BBC interviewed a pilot for American Airlines today who are still flying

737 Max. They have a custom software modification that allows the pilot to actually see what the AOA sensors are reading.

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2h 40m in - you may have to spoof/VPN from a UK IP address to listen.

Viewed from the outside it looks like Boeing has the FAA in its pocket.

Sometimes design simplicity is appealing when it is being made down to a price. The problem here was that the pilots were unaware of quite how capricious the aircraft MCAS flight control system could be and not all the pilots knew how to disable it.

I suspect some bad HCI issue here (which is unusual in aircraft design). Distracted by the shaking control stick they failed to notice the other indicators showing flight control surfaces doing crazy things.

That is how it is done in truly mission critical control systems.

Arguably this one wasn't so critical because the pilots *could* disable the bad behaviour if only they knew how. The problem stems from Boeing pretending that a radically new aircraft is a 737 to avoid higher training costs. 90 minute iPad course for conversion.

--
Regards, 
Martin Brown
Reply to
Martin Brown

As for the US Donald Trump has tweeted his official findings on the

It seems that marketing thought it was a good idea not to tell pilots

Arguably the crashes of these 737 Max flights may well be down to pilot error in the sense that they didn't know how to resolve the problems that a bad AOA sensor can cause to MCAS (or didn't think to do it).

However, that doesn't alter the fact that having a "safety" system that can go rogue to an extent that it makes a plane unflyable is not good.

They do have to be demonstrably better than humans though.

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Regards, 
Martin Brown
Reply to
Martin Brown

Yes. Although having said that it might only apply to those particular pilots since the previous flight leg was completed successfully with the same sensor fault - the difference was that they did the right thing after 12 failed attempts with the stick. The pilot that crashed tried 21 times with the same result every time. See the Seattle Times article.

Lion Air fault reporting and maintenance procedures are allegedly not very good.

Boeing pretended it was just a 737 - 90 minutes on an iPad conversion.

Although it is too early to be absolutely certain the pattern of climb and power dive looks suspiciously similar. The big difference being that starting out at high altitude and in mountainous terrain these pilots had less lift and less height to play with when things went wrong.

Once the flight data recorders have been analysed then we will know for certain until then it is all speculation. TBH I would prefer it to be the same known fault rather than another entirely independent one.

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Regards, 
Martin Brown
Reply to
Martin Brown

That is always going to be a problem on large scale projects.

737 Max having MCAS was not declared to pilots by Boeing if the guy from American Airlines the BBC interviewed this morning is to be believed. He also said that American has a custom software mod that lets them see the AOA sensor readings in the cockpit.

One serious snag with fly by wire is that garbage in garbage out.

Mention has been made in the UK press that because of the weight and position of the new physically bigger engines on the 737 Max it relies on computer control for flight stability and that MCAS is a hasty software bodge to sort out a thrust vs centre of gravity issue taking it nose up. This article puts a somewhat less judgemental slant on it:

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Pilots certainly were not happy when they found out:

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An automatic stall prevention system that avoids stalls by flying a working plane into the ground is clearly not fit for purpose.

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Regards, 
Martin Brown
Reply to
Martin Brown

Here is the report of the investigation:

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It is striking that by the time a crack was 1/4" long (and still very hard to detect) it had already used up 90% of the fatigue life of the structure. Once a crack was a few inches long catastrophic failure was imminent.

John

Reply to
jrwalliker

My instructor said "power controls height, pitch controls speed." For a light aircraft, it quickly becomes second nature.

Though this isn't really true to the physics of the situation, in which both pitch and power affect both speed and height. Indeed, in a typical single engined light aircraft, when you apply power, you'd better be ready to push the stick forward, or the aircraft will pitch up, and lose speed, because the increased airflow over the tail (from the propellor) pushes it down.

Airliners tend to be flown using the opposite paradigm - thrust controls speed, stick controls height. Perhaps the pilot in question took that too literally, having never acquired a deeper understanding of the physics involved.

Sylvia.

Reply to
Sylvia Else

Sylvia Else wrote in news: snipped-for-privacy@mid.individual.net:

That understanding/'rule' applies to those passenger jets which ARE already moving at well over stall speeds.

During the ascent phase of a flight, the plane ascends at the fastest rate possible while still maintaining a better than stall speed.

This ascent phase and standard operating behavior needs to be looked at. It is easier to hike up a long hill slope than to climb the steep climbing face. Easier on the body too.

OK... hiking metaphor. But it is true.

Need more stringent acceptance criteria for pilots as well.

Limousine drivers too. Anywhere the ferrying of passengers is involved.

Reply to
DecadentLinuxUserNumeroUno

I thought Juan didn't believe that was *all* his flying hours, but must have been all the hours in a 737 Max8.

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 Thanks, 
    - Win
Reply to
Winfield Hill

On Mar 13, 2019, Winfield Hill wrote (in article ):

Yeah.

politicians claiming otherwise.

But to keep things in perspective, the risk of dying in a civil aviation accident is less than one in a million takeoffs.

The fact that we had two accidents in less than a year involving the same make and model of airplane (which was new) owned by different airlines certainly tells one to study this make and model quite closely, but does not tell us what is actually the root cause. And, while unlikely, it still could be coincidence.

Joe Gwinn

Reply to
Joseph Gwinn

I remember flying straight up in a Cessna Aerobat until it stalled and fell down backwards. The pilot was really good, and the Aerobat naturally wanted to snap out of stalls; a 737 doesn't. Of course, you need some altitude.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics
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Reply to
John Larkin

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