Air Crash Thread: Boeing MAX and Other Problems

TenEightyOne

TenEightyOne

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TenEightyOne
TenEightyOne
On the 29th October 2018 an Indonesian flight, Lion Air 610, crashed shortly after takeoff from Jakarta. You can read more about the crash here.

The aircraft type involved was the new Boeing 737 MAX 8, a "fourth generation" of the venerable, and statistically safe, 737 design. A particular feature of the new design is the uprated engines - they're heavier and they sit further forward than on previous generations. This causes them to push the aircraft's nose upwards when high power is used. The updated flight software counters this by measuring the AoA (angle of attack) and pushing the nose back to where it should be. Investigators have found that the aircraft had suffered problems with its AoA sensors and it's likely that the final report will show that the pilots were fighting an aircraft that wanted to push its nose down for falsely-sensed reasons. Boeing made changes to their instructions for type conversion and are issuing a software update in April 2019.

Two days ago Ethiopian Air flight 302 crashed in very similar circumstances. The plane climbed out of the airport, showed wildly varying vertical speed indications on the radar, requested a return to the airport but sadly impacted terrain. It's far too early to say that these incidents are definitively related but it's clear that the similarities should be a cause for concern.

The FAA (Federal Aviation Authority) have issued a Continued Airworthiness notice for the type and have stated that they don't believe there's a reason to ground 737 MAX 8s just yet... but now various aviation authorities around the world are taking matters into their own hands. Singapore and Australia have banned the type from travelling in their airspace until investigations are complete. More countries are expected to follow suit quite quickly. Clearly this is a problem for Boeing with orders of MAX-8, and the -7 and -9 types ready to be built and delivered.

I'd be interested in the thoughts of the other aviation fanatics on GTP, should MAX-8 be grounded, is it too soon to say, is the new "unbalanced-by-design" engine configuration a step too far?

EDIT: An interesting article on the flight "augmentation" system (MCAS) that's at the centre of current scrutiny.

EDIT2: An infographic showing that the MAX 8 is the second least safe passenger jet of all time if fatalities are used as an indicator. It should be remembered that at present this is due to the low number of flights of the 300-ish(?) completed aircraft. Concorde crashed once but is at the top due to the far fewer number of passengers carried across its lifetime. Still, the graphic demonstrates the reason for concern with two similar crashes on type in 5 months.

9dwlyeiypml21.png
 
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It's not too long since Boeing had problems with another of its new planes, the 787 Dreamliner.

I am sorry for those who died in the crashes; I read yesterday that a Slovak MP lost his wife and children in the Ethiopian crash.
 
TenEightyOne
is it too soon to say, is the new "unbalanced-by-design" engine configuration a step too far?

EDIT: An interesting article on the flight "augmentation" system (MCAS) that's at the centre of current scrutiny.
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You are probably asking the good questions here and hitting on the right points, IMHO.

When I first worked on the 737 line back in '68, it was a different airplane, particularly in the flight control systems, being all mechanical, with "fly-by-wire & computer" being far in the future. Pilots loved the 737 for its intuitive and honest flying characteristics. Economics and technology have made those old-timey qualities rather obsolete, if occasionally with tragic consequences. God rest the souls who sacrificed their lives on the altar on economics and technology.
 
TenEightyOne
View attachment 806089
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Those statistics are ridiculous. Plane crashes are mostly chance events, and you can’t say anything about chance unless you have a big sample of events. One or two events is not a big sample.

It’s like rolling a die a handful of times and then making conclusions about the chance to roll a specific result.

It could be something about the design that makes it less safe, but it could also be complete chance.
 
Dotini
God rest the souls who sacrificed their lives on the altar on economics and technology.
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Augmented flight controls aren't exactly new. While there may be a problem with MCAS (and there was absolutely a problem with Boeing keeping it secret), the existence of such a system doesn't imply to me any kind of carelessness or a sacrifice of lives.

I'm not sure if the 737 needs to be grounded but it would seem like a good precaution to take. The other thing that bothers me about this though is how many airliners don't actually have an AoA indicator. It seems absurd to me to fly without one, yet so many planes have no such thing in the cockpit. They're optional on the 737, I don't know if the flight in question had one.
 
It's just been announced that the UK civil aviation authority has just banned all 737 MAX aircraft from UK airspace. This is pretty big news, obviously they don't deem the aircraft safe until they know whats going on, like the other countries that have already grounded them (so far Australia, China, Singapore & Indonesia).

 
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CAA
The UK Civil Aviation Authority has issued instructions to stop any commercial passenger flights from any operator arriving, departing or overflying UK airspace.
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Oh I bet Flightradar is fun to watch right now.

Edit: Oh, unlucky.
 
TenEightyOne
On the 29th October 2018 an Indonesian flight, Lion Air 610, crashed shortly after takeoff from Jakarta. You can read more about the crash here.

The aircraft type involved was the new Boeing 737 MAX 8, a "fourth generation" of the venerable, and statistically safe, 737 design. A particular feature of the new design is the uprated engines - they're heavier and they sit further forward than on previous generations. This causes them to push the aircraft's nose upwards when high power is used. The updated flight software counters this by measuring the AoA (angle of attack) and pushing the nose back to where it should be. Investigators have found that the aircraft had suffered problems with its AoA sensors and it's likely that the final report will show that the pilots were fighting an aircraft that wanted to push its nose down for falsely-sensed reasons. Boeing made changes to their instructions for type conversion and are issuing a software update in April 2019.

Two days ago Ethiopian Air flight 302 crashed in very similar circumstances. The plane climbed out of the airport, showed wildly varying vertical speed indications on the radar, requested a return to the airport but sadly impacted terrain. It's far too early to say that these incidents are definitively related but it's clear that the similarities should be a cause for concern.

The FAA (Federal Aviation Authority) have issued a Continued Airworthiness notice for the type and have stated that they don't believe there's a reason to ground 737 MAX 8s just yet... but now various aviation authorities around the world are taking matters into their own hands. Singapore and Australia have banned the type from travelling in their airspace until investigations are complete. More countries are expected to follow suit quite quickly. Clearly this is a problem for Boeing with orders of MAX-8, and the -7 and -9 types ready to be built and delivered.

I'd be interested in the thoughts of the other aviation fanatics on GTP, should MAX-8 be grounded, is it too soon to say, is the new "unbalanced-by-design" engine configuration a step too far?

EDIT: An interesting article on the flight "augmentation" system (MCAS) that's at the centre of current scrutiny.

EDIT2: An infographic showing that the MAX 8 is the second least safe passenger jet of all time if fatalities are used as an indicator. It should be remembered that at present this is due to the low number of flights of the 300-ish(?) completed aircraft. Concorde crashed once but is at the top due to the far fewer number of passengers carried across its lifetime. Still, the graphic demonstrates the reason for concern with two similar crashes on type in 5 months.

View attachment 806089
Click to expand...

It sounded like Boeing released training to pilots for how to handle the scenario where the nose is being dropped inappropriately. My guess (and this is total speculation) is that the Ethiopian Air pilots had not received the training. That would be (and this is total speculation) probably why the plane is still rated as airworthy in the US. There is a known procedure for dealing with the issue.
 
Danoff
It sounded like Boeing released training to pilots for how to handle the scenario where the nose is being dropped inappropriately.
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They have now, but information was only added to the manual (and therefore training) in response to an FAA Emergency Airworthiness Directive after the Lion Air crash. Airlines are now adding it to their training. We have to await the final report on that crash but it seems likely that this omission could be material to that incident. It's too early to say how that information release was handled by Ethiopian Air, of course, but in all they're a very safe airline and it's hard to imagine that as a flagship operator they weren't aware of these developments.

Robin
It's just been announced that the UK civil aviation authority has just banned all 737 MAX aircraft from UK airspace.
Click to expand...

France, Norway and Ireland have now done the same. European operators are also electing to ground their own MAX 8s.
 
FoRiZon
And now people compares this Boeing incidents to McDonnell Douglas (specifically the DC-10) on 1979.
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Ahem, the Boeing Company was taken over by the management team of McDonnell during the 90's.

Boeing, the venerable aviation company established by and for engineers was taken over by businessmen, accountants and lawyers. It has not been the same since. Sic transit gloria mundi.
 
In a worst case scenario where there's another MAX 8 crash, this time inside the US, I wonder how the liability would look given that the type has effectively been grounded in the majority of its other operating territories?
 
TenEightyOne
In a worst case scenario where there's another MAX 8 crash, this time inside the US, I wonder how the liability would look given that the type has effectively been grounded in the majority of its other operating territories?
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That would fall on the FAA, and it's very hard to sue the government for this sort of thing. Airlines would pass the buck to the FAA. I was going to say that someone has to be wrong, either the decision to ground is wrong, or the decision to fly is wrong. But that may not be true. It's possible that training within the US is such that continuing to fly is safe, while training in other territories is such that it is not safe to continue to fly.

Of course it's still possible that they're unsafe and that they shouldn't be flown in the US regardless of updated training, but I'd expect the FAA to jump on that (and airlines tbh). It's also possible that it's safe to continue to fly outside the US based on updated training, and I'm not sure I trust governments to stand behind that determination, opting instead to ground the planes at great cost in order to preclude a potentially embarrassing political scenario. It's harder to get kicked out of office for unnecessarily wasting money and time than it is to get kicked out of office for properly declaring the planes safe only to see a screw-up result in another crash.

Lots of possibilities still it seems. I continue to expect the latest crash to be blamed on not following the updated procedures. It will be interesting to hear the results of that investigation.
 
If there was a correlation between the accidents and the nose-up problem, it wouldn't be the first time that the 737 family had had a fatal operating flaw.

Unfortunately, sometimes the only way we can whittle out our flaws and improve our technology is through unforeseen deaths.
 
Dotini
You are probably asking the good questions here and hitting on the right points, IMHO.

When I first worked on the 737 line back in '68, it was a different airplane, particularly in the flight control systems, being all mechanical, with "fly-by-wire & computer" being far in the future. Pilots loved the 737 for its intuitive and honest flying characteristics. Economics and technology have made those old-timey qualities rather obsolete, if occasionally with tragic consequences. God rest the souls who sacrificed their lives on the altar on economics and technology.
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To a certain extent I agree. However there is no doubting that technology used in modern aircraft has ushered in an era of incredibly safe air travel.

The problem with this technology is that it has eroded airmanship - some would argue that pilots these days manage the aircraft as opposed to flying it, which is all well and good until something goes wrong and the flight management computers (there are a few) decide they can no longer fly the aircraft, degrade the flight controls into mechanical law (this would be Airbus' terminology for direct pilot control meaning inputs go directly to the control surfaces), and say "Hey meatsacks, it's up to you now", and the problem with this is that the majority of airline pilots will likely never encounter this scenario in their entire career, at least outside of the simulator, so when it does happen they are ill prepared for it.

I'm not saying that's the case here with 737 MAX models. For 2 to go down in such a short period of time would seem indicate a systemic problem somewhere, either with the flight management system, or inadequate pilot training on the new aircraft, but failure on the part of the pilots to recognise when the flight management system given up has been cited as a cause for some relatively recent high profile fatal crashes - specifically Air France flight 447 in 2009 springs to mind.
 
I've spent some time discussing this on Reddit and a lot of people aren't making sense of the published flight data.

This plane never made it above about 1400 agl. It merely porpoised at low altitude, with climb power, which means it accelerated all the way to 380 knots before it crashed. The impact itself wasn't what people think, that of a plane falling out of the sky like a missile at a million miles per hour. And frankly, I'm not even sure the plane stalled at all because it continued to accelerate at a fairly steady pace while bucking up and down. We know the airport is surrounded by higher terrain that requires immediate climbs so it seems to me like the plane just never climbed and ran straight into it. The pilots must have been fighting the MCAS which was acting on false data again, causing the plane to nose down to eliminate the "stall", then the pilots to pull up as normal, then the plane to eliminate the "stall" again, then the pilots to pull up etc. It was a helluva ride for sure.

Boeing's computer is acting on bad data, possibly from bad AOA sensors. Odd that it would only be one sensor though, as the plane has multiple sensors of everything and the computer has to cross-reference them all to eliminate possibly faulty inputs.
 
Reading Boeing's statements a little more carefully, I think I see their point of view here. They issued a response to a known issue with the MAX, they believe it corrected the problem. A new crash aboard a MAX has occurred, and until they analyze what happened, they're not willing to speculate. So for example, they're not willing to say that it was the same thing that happened on other flights, that the pilots responded according to their procedures, etc. etc. They're reserving judgment until they know what took the plane down. They're not willing to issue a declaration until they have some new information to base it on, and a crash (which can be caused by many things) by itself is not sufficient for them to act on.

I think I get it, it's very engineering (despite what @Dotini says). It's very by the numbers.
 
Keef
This plane never made it above about 1400 agl. It merely porpoised at low altitude, with climb power, which means it accelerated all the way to 380 knots before it crashed. The impact itself wasn't what people think, that of a plane falling out of the sky like a missile at a million miles per hour. And frankly, I'm not even sure the plane stalled at all because it continued to accelerate at a fairly steady pace while bucking up and down. We know the airport is surrounded by higher terrain that requires immediate climbs so it seems to me like the plane just never climbed and ran straight into it. The pilots must have been fighting the MCAS which was acting on false data again, causing the plane to nose down to eliminate the "stall", then the pilots to pull up as normal, then the plane to eliminate the "stall" again, then the pilots to pull up etc. It was a helluva ride for sure.
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Earlier profiles for the same flight (route) show it making a turn after it leaves the airport. In this case it climbs straight out (over rising terrain) as the pilots, presumably, start pan-pan and request a return. The vertical speed data is horrible, the plane wanted to fight its way downwards. I'm not sure I'm entirely comfortable with "alternate law" stick pushers as an idea, it seems that in certain freak circumstances it's able to overcome the pilot's own flying instincts.
 
TenEightyOne
Earlier profiles for the same flight (route) show it making a turn after it leaves the airport. In this case it climbs straight out (over rising terrain) as the pilots, presumably, start pan-pan and request a return. The vertical speed data is horrible, the plane wanted to fight its way downwards. I'm not sure I'm entirely comfortable with "alternate law" stick pushers as an idea, it seems that in certain freak circumstances it's able to overcome the pilot's own flying instincts.
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Stick pushers have been commonplace for a long time now but they're different than the MCAS that Boeing put on the MAX. No other airplane has it, and it's not a stick pusher. The MCAS changes the trim of the entire horizontal stabilizer rather than adjusting the elevator. You mention that the plane's thrust can cause the nose to rise but that's not the core of this problem - every plane with low-mounted engines experiences some nose rise when increasing thrust and nose drop when reducing it. The unique problem with the MAX is that the new engines are larger, meaning they're mounted higher and further forward than older 737s. From a center of gravity perspective, this should actually reduce nose rise and increase stall resistance, but because the cowling shape is more extreme than older 737s - virtually flat on the bottom and strongly curved on top for ground clearance - the cowling itself creates lift at high angles of attack, basically like a high-camber low-aspect ratio wing. The problem this causes is that the center of lift of these cowlings is very far forward of the plane's center of gravity, and because of their low aspect ratio their lift increases drastically as AOA rises, like the wing of a bush plane. Combined, this all results in relatively extreme nose rise under thrust, and at the worst time which is during high AOAs.

Boeing is already working on a replacement for the 737. When they designed it, they made it very low to the ground which is a severe limitation given that bigger turbofans are more efficient. The engines on the MAX are so big that they had to jury rig a system to combat instability caused by putting engines where they were never supposed to be. Hell, at this point they might as well mount them on top the wing like a Honda Jet.
 
Boeing has delivered nearly 400 of the MAX 737's, and has orders for ~5000 more. This is the cash cow. The financial future of The Company AND MY PENSION depends upon them being delivered and flown. Don't get chicken now. Technology will get us out of the hole that technology has put us into. It's that or death. No other choice.
 
"The Ethiopian Airlines plane that crashed killing 157 people was making a strange rattling noise and trailed smoke and debris as it swerved above a field of panicked cows before hitting earth, according to witnesses."

Investigators found two black box recorders on Monday, which will help piece together the plane’s final minutes.

“When it was hovering, fire was following its tail, then it tried to lift its nose,” said another witness, Gadisa Benti. “When it passed over our house, the nose pointed down and the tail raised up. It went straight to the ground with its nose, it then exploded.”
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https://www.reuters.com/article/us-...-shuddered-before-deadly-plunge-idUSKBN1QS1LJ
 
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Keef
Stick pushers have been commonplace for a long time now but they're different than the MCAS that Boeing put on the MAX.
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I realise it isn't a physical stick pusher, I meant it more generally and should have been clearer. As you say, MCAS affects the stabs.

Keef
Hell, at this point they might as well mount them on top the wing like a Honda Jet.
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It makes me wonder where unflyable (or deliberately unbalanced) design ameliorated by "control augmentation" systems ends up.

Dotini
"The Ethiopian Airlines plane that crashed killing 157 people was making a strange rattling noise and trailed smoke and debris as it swerved above a field of panicked cows before hitting earth, according to witnesses."

https://www.reuters.com/article/us-...-shuddered-before-deadly-plunge-idUSKBN1QS1LJ
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I'd seen some of those claims earlier but that's the first solid source I've seen. Interesting... ground collision that's been unreported? Explosion? Seconday collision with a ground object during a control failure?
 
TenEightyOne
I'd seen some of those claims earlier but that's the first solid source I've seen. Interesting... ground collision that's been unreported? Explosion? Seconday collision with a ground object during a control failure?
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If speculation is permitted, maybe he dragged his tail on takeoff? Too much ganja in the maintenance hanger?

At age 29, Yared Getachew was the youngest captain at Ethiopian Airlines, though he had accrued 8,000 flight hours.

The first officer, Ahmed Nur Mohammod Nur, had logged only 200 flight hours.
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