737 problem explained

On Dec 20, 2019, snipped-for-privacy@highlandsniptechnology.com wrote (in article):

Paywall; article not read.

Nah. I follow the story in Aviation Week. The problem is not bad coding

were insufficient to the problem, and the people in Boeing that pointed that out were ignored.

The most striking example of this is the decision to bet the airplane on the correct operation of a single attitude sensor -- attitude sensors are famously trouble-plagued.

Joe Gwinn

That's a coding problem. The programmers did what they were told, when it should have been obvious to them that it was dangerous.

--
John Larkin         Highland Technology, Inc 

lunatic fringe electronics

There is zero chance that the same set of people will be expert coders, pilots, expert sensor engineers, expert system and safety engineers.

Hence it is unrealistic to expect the coders to have realised the dangers.

It is unrealistic to expect the coders to have been able to override the specifications they were given, doubly so when experienced staff tried and failed to rectify the issues.

I wouldn't code a system that I don't understand, and I wouldn't write code that endangers people.

--
John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

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MCAS was not supposed to be that critical to flight safety. It only becomes a problem with poorly trained foreign pilots with insufficient aptitude fo r flying complex systems. Boeing is at fault for their defective training, and then only partly. The American pilots who experienced this same phenome non stated all they had to do was shut the friggin MCAS off and fly manuall y. The real problem is low aptitude pilots, mostly foreign, who rely 100% on e very auxiliary flight control possible, and can barely fly the aircraft man ually, kind of like a blind person driving a self-driving car.

em#AoA_Disagree_alert If you want to stay pinned to your seat watching some really excellently an imated flight disasters and near flight disasters, check out the X Pilot ch annel on youtube, all short and sweet 10-15 minute duration stuff.

Right. But also, you wouldn't work as a donkey, writing reams of inscrutable aircraft systems code.

--
 Thanks, 
    - Win

It is not a coding problem - it is a system design problem.

What puzzles me as a pilot is the fact thet the attitude indicator (artificial horizon) information was not used as augmenting data. In both accidents, MCAS put the aircraft to an unhealthy nose-down attitude.

The poor pilots had only seconds to detect and muscle the runaway elevator trim.

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-TV

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The angle-of-attack sensor and the artificial horizon measure two different things. It is entirely possible for them to differ by large amounts. Lik ewise the air speed sensor and ground speed are very different things.

--
  Rick C. 

  - Get 1,000 miles of free Supercharging 

That is right - but it is always unsafe to turn an airliner into an impossibly steep attitude.

If pitch attitude and airspeed are correct, it is pretty difficult to have an incorrect angle of attack, if the aircraft is loaded correctly.

--

-TV

They can't even build planes anymore, so that's no surprise. And it was essentially a design spec that was put into code that allowed a single sensor failure to put the 737MAX into an impossible, or near impossible, to recover from situation.

I think this all went wrong circa 2000 when they moved their headquarters from WA state to Chicago, away from any engineering, design, or production. They also bought Lockheed and somehow the Lockheed management and corp culture replaced that of Boeing.

One big question is how that Mullenberg CEO is still there? He must have dirt on the board or something.

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What story are you following? He;s posting about the just failed launch of the Boeing Starliner. You seem to be talking about the 737MAX.

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rent things. It is entirely possible for them to differ by large amounts. Likewise the air speed sensor and ground speed are very different things.

Too many IFs for me to read. Can you show the ELSE, END and indentation fo r each condition?

--
  Rick C. 

  + Get 1,000 miles of free Supercharging 

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es a problem with poorly trained foreign pilots with insufficient aptitude for flying complex systems.

That's BS. American pilots are outraged at what Boeing did and have spoken out, saying it's unsafe. That includes Capt Sullenberger. There was no check that there was a sensor indicating an abnormal angle when the plane was on the ground. It could be stuck at 35 deg, instead of zero, no indication. Plane takes off and at a few thousand feet, they retract the flaps. That enables MCAS and it immediately puts the plane into an extreme nose down and keeps doing it. Yes, pilots are trained for runaway trim and should be able to deal with it. But being trained and correctly identifying the problem, taking the right steps, when you only have a couple minutes, is another story.

Additionally, the second crash, in Ethiopia, the pilots did correctly identify it and they did take the steps. It was the young co-pilot who identified it, he hit the trim cut off switches, then tried to trim manually. He said he couldn't. Which is consistent with what we now know. If the plane is going fast enough, MCAS pushes trim down hard, it may be impossible for the pilots to put enough force on the trim wheels to move them. In fact, Boeing decades ago pointed that out for all 737s. They advised pushing the controls forward, temporarily putting the plane in a steeper dive, to relieve the pressure enough so the wheels could be turned. It was removed from later training manuals.

Also, so far no NTSB reports have been issues, so IDK on what basis you are concluding that the foreign pilots were inadequately trained. Simple fact is this problem never happened with a US carrier period.

Boeing is at fault for their defective training, and then only partly. The American pilots who experienced this same phenomenon stated all they had t o do was shut the friggin MCAS off and fly manually.

The problem never happened with a US carrier. It only happened three times and two of three were fatal. If you have a cite that shows otherwise, I'd be happy to see it.

every auxiliary flight control possible, and can barely fly the aircraft m anually, kind of like a blind person driving a self-driving car.

BS. NTSB has issued no report. We don't know how much foreign pilots were trained on runaway trim recovery vs US pilots. But it is an important part of basic flight training.

On Dec 20, 2019, Whoey Louie wrote (in article):

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Ahh. I am. The actual article was behind a paywall, and so not read, as mentioned above.. But the excerpt was talking about the 737 Max 8, which did have the problem with the attitude measurement units. I gather then that people were wondering if Boeing had lost it.

Joe

On Dec 20, 2019, snipped-for-privacy@highlandsniptechnology.com wrote (in article):

requirements

notice and complain, but to no avail -- they are required to follow the requirements as written, enforced by an immense cross-checking process.

This software must have been done to DO-178c, a process easily ten times as heavy as standard-issue development of military mission software, which process is a large factor heavier than that for ordinary commercial software

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The 1999 Gripen crash is an example of what can go wrong:

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Control laws are written by aerodynamics engineers, not programmers.

Joe Gwinn

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Lockheed-Martin will be surprised to learn this.

There are not that many people competent to run such a large company, so it will take more than this.

Joe Gwinn

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he American pilots who experienced this same phenomenon stated all they had to do was shut the friggin MCAS off and fly manually.

on every auxiliary flight control possible, and can barely fly the aircraft manually, kind of like a blind person driving a self-driving car.

Here ya' go, simple minded MOH-WAHN, who thinks he knows everything, but is actually wrong about everything:

Read the results of ASRS search, which is the real truth versus the total b s corrupted by FAA and NTSB bureaucracy.

"...these U.S.-carrier pilots disabled or overrode automated systems and to ok control of the plane themselves. Obviously none of these flights crashed ."

Foreign pilots from radically different cultures are not the same as Americ an pilots, not even close. And failure to recognize this fact....never mind ... backwater mindless people like you aren't worth the time it takes to fi nish a sentence.

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If you believe that, you must still be wearing diapers. The entire software process as it related to MCAS was quite informal to put it mildly. The joke programmers just winged it, and no one really gave a damn. That's how they ended up with 2.5o trim capabiity.

There are very very /very/ few people that understand /all/ aspects of specifying aircraft and flying aircraft. They are very complex systems with a lot of emergent behaviour.

There certainly aren't enough such people, and I'll bet none of them are coders.

If everybody took your line, there would be no modern aircraft.