[bodas]

They say that most accidents are a sequence of several failures, but from what's in this article it sure seems to me like 100% Boeing's fault.

If the only maintainence problem with this aircraft was a broken sensor, then that is almost irrelevant because sensors can break during flight too.

If it's really true that a mere broken sensor can cause the computer to ram the aircraft into the sea, then someone at Boeing really fucked up. Where are the redundancies and sanity checks?

[bsaul]

From the article :

Pilots and former safety regulators said that Lion Air flight and maintenance crews regularly filled out two log books, one real and one fake, to hide malfeasance.

If that’s true, i wouldn’t quite call it 100% boeing.

[bodas]

Here we have an Indonesian company with a terrible safety record and an aircraft that hasn't been maintained properly.

However, if the computer is found to have initiated the pitch downwards, then the same failure could happen to any aircraft of this type, even if well maintained, if the sensors or computer simply begin to malfunction while the plane is in the air. Absent pilot error, the worst that should happen is a reversion to manual control.

What concerns me is that any software flaws with the aircraft will not be addressed until the problem reoccurs with another more reputable airline in the future, because Lion Air appear so guilty in this case.

[raverbashing]

I'm not sure how it works on that specific model, but it's usual that a disagreement between sensors doesn't trigger a direct action like pitch down.

It will more likely trigger a 'fallback' action like turning autopilot off (or changing flight mode which is what happened on AF447)

[VBprogrammer]

It sounds like a trim runaway incident. This has been a known issue since the earliest days of electronic trim controls.

For those who don't know, trim is the system by which the neutral position of an aircraft's controls is set. In this case in pitch. An aircraft will fly at more or less a fixed speed for a given trim setting, slowing down will cause it to pitch down unless a correcting force is applied to the controls, and speeding up will cause it to pitch up. The problem is that in a severe out of trim condition it can take tens of kilograms of force to maintain the desired pitch.

Trim runaway is when the trim motor for whatever reason doesn't stop moving, in the simplest systems this is sometimes caused by faulty switches. Most aircraft actually have a switch which is split down the middle but is naturally pressed as if it were one. This requires two of the switches to fail to get this situation. There are usually trim in motion indicators and alarms if it's in motion for too long which are intended to help pilots avoid this situation.

I suspect the computer drove the trim heavily nose down, as a result of the envelop protection trying to avoid a stall. The pilots probably tried to intervene or the autopilot handed them the aircraft back knowing something wasn't right. At that point the trim was mis-set enough that they failed to recover correctly.

Mostly conjecture but it fits what I've read.

[sokoloff]

It’s also possible for the flight crew to have been fighting the AP (often inadvertently), resulting in auto-trim continuing to trim against them.

If the crew applies sustained pitch up inputs, above what the flight director is commanding, the auto-trim will apply trim down to compensate. This can result in pilot applying even more pitch up input, resulting in more trim down. Solution of course is to kill the AP and trim motors, the multiple means of how to do so is a memory item in every aircraft.

Trim runaway has caused accidents to be sure, but is still a flight crew error IMO, unless every means to kill the trim was tried and failed.

[Brockenstein]

I'm quite sure Boeing is not going to ignore this because Lion Air is a crummy airline...

[xfitm3]

Indonesian airlines have a terrible reputation for safety.

https://en.wikipedia.org/wiki/List_of_aviation_accidents_and...

[danso]

From my complete layperson perspective, this flawed-sensor/autopilot failure feels even more inexplicable than Tesla's Autopilot failing to stop for stationary objects. In the latter case, I can grasp how it's difficult -- or at least an open-ended problem to train a system to distinguish such objects in real time. But the heuristics for stable flight seem much more bound to hard-coded heuristics and physical facts -- isn't there a calculable, mostly-predictable limit -- for any given altitude -- to how much a plane can correct for a stall by nosediving. And when this limit is approached, shouldn't the plane's autopilot cede more control to the human pilot, if there's no indication that the pilot is otherwise incapacitated?

But it sounds like there's still a lot of unknowns about sensor readings and chain of events -- for all we know, it's possible the plane made a reasonable auto-correction, but the pilots misinterpreted the sensor readings and inadvertently caused the plane to go into an uncontrollable dive. Given that this is the Boeing 737 Max 8's first major crash, and it happens to be with one of the most unsafe budget airlines, it seems premature to say Boeing is at 100% fault. OTOH, 1 crash/189 deaths of a new plane, of a model that has had just 2 years of service so far, is not a statistic that justifies giving Boeing the automatic benefit of the doubt.

edit: Also, the Lion Air plane was said to have had the same major glitch with its airspeed indicator in all of its 4 final flights [0]. Even if Boeing's design is found to have shortcomings, Lion Air choosing to not ground the plane despite 4 consecutive flights of buggy behavior is a huge indictment of its safety culture.

[0] https://www.popularmechanics.com/flight/airlines/a24568956/l...

[simias]

I'm not saying that you're wrong or that one couldn't come up with a better algorithm but at the same time I wonder if it's a good idea to have ultra-complicated heuristics in something like an airplane. For one thing a complicated heuristic with many inputs and weights is a lot harder to validate and can lead to strange and unexpected failure modes.

Besides that the problem of having a very clever autopilot is that it makes it a lot harder for humans to react appropriately when it messes up, because they both don't expect it and are more likely to panic. The Tesla autopilot accidents are good examples of that, those have seen would've been easily avoided by a human but because the autopilot was usually fine on its own the driver didn't react quickly enough.

An other much more tragic example is the Air France Flight 447 crash in the Atlantic where the autopilot detected a faulty sensor and disengaged and the two pilots managed to get the otherwise perfectly functioning plane to crash into the ocean because they basically freaked out and failed to understand what was going on.

That's a strange paradox in a way, as we move from fully manual to fully automated we have a strange "uncanny valley" for safety where the computer is clever enough to handle most situations which lulls the human operator into a false sense of safety. The operator pays less attention, eventually starts losing their skills and reflexes and then at some point, maybe years later, the computer messes up and you have a handful of seconds (if even that) to remember what you're supposed to do.

On the other hand a simple but predictable autopilot might not be quite as autonomous but at least it's easy to understand and anticipate, and it forces humans to remain attentive.

[rjvs]

If the sensors are giving the software false altitude readings, how would your heuristics help?

[village-idiot]

There’s more than one sensor, expecting one to give bad readings is something that should be handled.

[asdfasgasdgasdg]

This is my question: why just one AoA sensor? It seems like there is plenty of space on the nose to put two or even four. Their results could be averaged. Presumably the MTBF for any individual AoA sensor is quite low (if we're happy to fly planes with just one right now), so this shouldn't cause too much of an increase in maintenance burden.

I don't actually know how many AoA sensors there are, but the NYTimes article seems to refer to refer to them in the singular when talking about this plane.

[village-idiot]

Every article I’m reading says “AoA sensors”, which implies more than one. I think the flight computers did not correctly handle one of several sensors providing bad data.

[skgoa]

> isn't there a calculable, mostly-predictable limit -- for any given altitude -- to how much a plane can correct for a stall by nosediving. And when this limit is approached, shouldn't the plane's autopilot cede more control to the human pilot, if there's no indication that the pilot is otherwise incapacitated?

There is, but there will always be a dependency on sensors to feed the input values into these funcitons. Modern flight computers are far better at pretty much any flying task than humans. Other than communicating wiht traffic control and raising/lowering the flaps and gear (none of which are absolutely necessary), a modern airliner can take off, cruise and land entirely on its own, with no human intervention.

I agree that it's probably a combination of bad maintenance, a not quite perfectly fault-tolerant system design and human error of the pilots. One factor that hasn't been mentioned is that even the newest versions of the 737 contain ancient, obsolete technology. A newer airliner will probably have more redundant and more fault-tolerant systems.

[Piskvorrr]

Nope. Nope nope nope. It can, very theoretically, do each of those things, but it can't switch those modes, must not take off automatically (there's no safe way to do this, and therefore would be very illegal), and requires vigilance that's above manual w/r/t landing. Please stop perpetuating urban legends.

http://www.askthepilot.com/questionanswers/automation-myths/

[userbinator]

One factor that hasn't been mentioned is that even the newest versions of the 737 contain ancient, obsolete technology

You mean technology like... wings? ;-)

More seriously, the "ancient" stuff is such because its reliability has been proven over decades of refinement. "Don't fix what ain't broke," as the saying goes. The aerospace industry moves slowly for a reason. I'd much rather fly on an old maintained plane than the very newest.

[CPLX]

> Other than communicating wiht traffic control and raising/lowering the flaps and gear (none of which are absolutely necessary), a modern airliner can take off, cruise and land entirely on its own, with no human intervention.

Yeah no. This is obvious patent nonsense.

Relevant: I am a licensed pilot

[Retric]

A single operator handles multiple military drones. A large part of this is they can takeoff and fly to a specific location, and or land from a specific location on their own.

Their are many reasons a 747 is not setup to do this is, but it’s not technology that difficult. Ex: https://en.m.wikipedia.org/wiki/Autoland

[danielvf]

Just because other aircraft can to this today does not mean "a modern airliner can". No modern airliner currently has the capability to make remote controlled flights.

[JoeAltmaier]

Hm. Autopilots have been able to fly the whole plane for decades, from runway to runway. They're not permitted for whatever reason; there has to be a pilot in the seat. But honestly for most flights of airliners (not even just modern ones) the autopilot is in control almost all of the time.

Can they be remotely operated? I'm thinking putting a plane into autopilot has to be a remote operation by now. Its so trivial, how can they have left that out?

[snowwrestler]

Military drones sometimes fail to do these things correctly, but it doesn't really matter because they are drones.

[Retric]

So do manned military aircraft. The military does a crazy amount of flying so you need relative rates for similarly refined systems* to really compare them.

* AKA older designs have better understood failure modes.

[JauntyHatAngle]

Too early to say that, and it's still conjecture from what I can tell.

Bad maintenance, and/or airline culture could still be a big part of the incident if it turns out there were warning signs ignored or bad repairs done.

So I would still disagree that anything is conclusive and certainly not 100% Boeing's fault yet.

[ken]

"Boeing" is 100,000+ people, and many times more in contractors and subcontractors. As you say, there's redundancy and sanity checks. No one person is solely responsible for any system on a BCA aircraft.

Blaming "Boeing" here is about like blaming "Microsoft" for a bug in a Microsoft product, or "NASA" for Apollo 13. All the problems may have taken place in a building with that name on the door, but it's still very far from a single point of failure.

[yummypaint]

The whole point of a corporation is to protect the liability of the individuals in the company. I would argue Boeing and Microsoft are the correct entities to blame. After all, if the people who actually fucked up aren't individually liable, and the organization as a whole isnt responsible, then who is?

[wsc981]

100% Boeing's fault? I would disagree with you after reading the article. That plane should have never been allowed to fly after having problems for many days and without figuring out proper fixes. Perhaps Lion Air should have flown in some Boeing engineers to look at the plane.

[marcosdumay]

From the article, the plane has had 2 reports of sensor malfunction by the time it took off. If it was as simple as "sensor is bad -> plane falls", it would had fallen much earlier.

[isoskeles]

Is it Boeing or “someone at” Boeing?

[bsder]

> If the only maintainence problem with this aircraft was a broken sensor, then that is almost irrelevant because sensors can break during flight too.

It seems like none of the airplane manufacturers test what happens when sensors go AWOL.

How many more crashes are we going to get because a stupid sensor malfunctioned before someone finally slaps some sense into Boeing and Airbus?

[Piskvorrr]

Quite the opposite: you don't read about most sensor failures except in tweets "grr flight delayed again". In other words, malfunctions happen and are dealt with, that's non-news by definition. Saying "there's this one case on the news, therefore it's the only one observed" misrepresents the data entirely.

[VBprogrammer]

Really? Aircraft crashes are staggeringly rare. For the most part they are caused by the pilots of those aircraft.

I haven't read too much into it but I suspect this system was part of an envelope protection system designed to stop the pilots from being able to fly outside of the aircraft's performance limits. Once a fix is applied I'm sure this system will save many more aircraft than it harms.

[tialaramex]

Nitpick: Aircraft crashes aren't actually that rare, but Commercial Scheduled aircraft crashes are very rare. If you buy plane tickets you're far more likely to die driving to the airport than in a plane crash. But if your friend takes you for a fun trip in their Cessna that's a different story.

General Aviation is dangerous the same way private automobiles are dangerous. The operators take silly risks, they lack advanced skills, corners are cut on maintenance, procedures are not followed correctly. They usually have just one engine (if it fails this may be survivable but it's not good) one pilot (who doesn't need to be as fit and healthy as a commercial pilot, nor as well trained) and they aren't required to file a flight plan, which means they may not really even have a plan A let alone plan B.

[VBprogrammer]

I think it was clear I was talking about commercial aviation but to lend some balance to your post let me address some of the points.

General aviation aircraft operate in completely different circumstances. Using shorter, sometime grass, runways without the benefits of instrument landing systems. Usually outside of the ATC system.

The general aviation fleet is generally ageing. 30+ year old aircraft are not at all uncommon.

They have one engine; however it is about 2 steps below a lawnmower in terms of mechanical complexity. So long as it receives a fair supply of fuel stoppages are very rare.

I don't think you can make any connection between a lack of flight plan and the safety of a flight, other than perhaps that the search and rescue team might have a better chance of finding you if the worst happens.

There are plenty of non-commercial pilots who aspire to a standard of piloting which are at or above the level of commercial pilots (consider display pilots).

All in all, the level of safety in general aviation is roughly similar to that of riding a motorcycle.

[mrguyorama]

>I don't think you can make any connection between a lack of flight plan and the safety of a flight

Part of proper flight plans are taking the steps to mark out your emergency procedures and landing places for failures in several portions of the trip, including a few different failures during takeoff. Sure, it might just be "Turn into that field there and cross your fingers", but you've at least thought about it and planned before hand

[marcosdumay]

Last time I run over Brazilian statistics, being a random person inside a plane was about as dangerous as being a random person inside a bus (what is safer than a car).

There are two large features of that data. First there is the fact that scheduled fights carry more people than the other kinds, pushing the overall average into the "safe" region. Second, there is very wide difference between kinds of flight, where agricultural aviation can be more dangerous than riding a motorcycle in heavy transit.

[na85]

Hi, I work in airworthiness. You should educate yourself on the facts because you are way out of your lane here.