Hacker News new | past | comments | ask | show | jobs | submit login
Some airlines and regulators ground 737 Max in wake of Ethiopian Airlines crash (flightradar24.com)
165 points by mimixco 43 days ago | hide | past | web | favorite | 143 comments

This entire industry is (was?) based on "safety-first" principle. After two very similar incidents, I find it incomprehensible that airlines are still flying with this aircraft. Two catastrophic incidents within a few months for a new aircraft is simply unprecedented.

At the very least, MAX8 fleet should be grounded for a few days, just until the FDR/CVR of ET302 are analyzed. They've already found the boxes, so it should be only a few days before we have a preliminary report.

All indications are they already know what happened. This is entirely a result of Boeing trying to get this plane pushed through without requiring additional training. Problem being... they changed the behavior so that pilots flying it like a regular old 737 don't know what's happening.

I hope there is a lawsuit of some sort so that boeing doesn't pull this ever again.

The fact that a critical software (MCAS) is installed and not disclosed to the pilots is significant blow to their reputation.

Thats because its an USA company. You don't see it coming up in news, you don't see any lawsuits from other countries, and they will keep covering the real issue as long as they like. There have been incidents in past when corporations have leveraged USA influence to punish countries that have tried bringing airlines companies to justice(like when Indonesian airlines were barred from entering USA airspace because of them blacklisting a American airline). Had it been another company whole Airline would have been grounded and news channels would have been all over it.

The comet's first paying flight was May 2nd 1952, there were hull losses in Oct 1952 (no fatalities), March 1953 and May 2nd 1953. There were then 2 more in 1954.

Yes but that was 65 years ago and the context is completely different. Planes crashed all the time back then and our safety culture and technology has changed massively. These steam locomotives[0], that look like they were built by a farmer, were ~10 years old at the time. Comet was incredibly futuristic space age technology. But with no 3D CAD or FEA simulations. No X-ray or ultrasound metallurgy. Crack propagation wasn't understood. Also, there was no CRM, no safety gadgets like stick pushers/shakers. Most pilots and airline management were WW2 ex military and a couple of planes a year is nothing compared to the 4-5 they would lose in a typical bombing sortie. I think there was an attitude of it being regrettable, but just part of life. [0] http://www.railgiants.org/union-pacific-big-boy-back-head.ht...

> These steam locomotives[0], that look like they were built by a farmer

This is a little derogatory, considering the mechanical wonder a steam locomotive was back then and still is today.

What are you talking about?

1) is "built by farmers" supposed to be derogatory, because farmers are often very mechanically inclined and make the best of what they have.

2) Steam engines are very capable, complex beasts. The big boy that you linked to is one of the largest and more complex one's ever built. Diesel engines wouldn't pack this much power in a single unit for multiple decades to come.

2a) you do realize that basically every electrical power plant sans hydro and photovoltaic are basically steam (turbine) engines and these work horses of old sharer large amounts of experience to the power plants of today?

3) The safety culture of the railways has always been important, almost as much as it is for air travel. (Yes, there have been some high profile accidents recently, but comparing fatalities to total trips is still favourable.)

It appears to me you saw a picture of something that didn't look "modern" and thought that it was primitive. It also appears that you thought primitive means simple. Those are never good assumptions.

>Crack propagation wasn't understood

It was well enough understood. Square openings leading to stress risers and cracks has been known in ship building since at leas the 1940s.

Yet it was put into planes. So either it wasn't really understood in the context, or no one that knew about it was advising on the design of aircrafts.

The corners on the windows did have a fairly large radius. Just not large enough (hindsight being 20-20). I think they knew about it and thought they had more than enough margin for safety and then never thought twice about it until aircraft started falling out of the sky.

I oversimplified. It was understood in specific academic circles and to an extent by leading designers, but not widely by others. The cracks actually started at a hatch on the bottom of the plane which was added to the design without going through the full engineering design QA process.

Then it wasn't well enough understood...

Until it was cheap enough to manufacture with, aluminum hadn't been used in large structural components and the crack formation in aluminum is very different from steel.

With steel, if you add a large enough safety margin it will essentially never fail due to repeat stress cycles. With aluminum it doesn't matter how strong you design it, eventually cracks will form and it will fail.

ship don't go trough a thermal and pressurization cycle at every trip however.

it wasn't square window per se as much as metal fatigue

I honestly don't understand why Boeing themselves don't ground the airplane. Having individual countries and airlines slowly doing it for them, just generates a ton of negative news stories. And the longer they wait, the more it will seem like they only did it because of pressure.

And God forbid there was another crash, Boeing would be history.

If Boeing were to ground the aircraft, wouldn't that be seen as admitting there is a fault/safety issue with the design, and put Boeing on the hook for compensation payments to airlines?

A number of Boeing 787s were grounded last year due to faulty Rolls-Royce engines, and it has cost RR hundreds of millions in compensation - to cover the airlines costs of leasing replacement aircraft, for example.

However, you're quite right that if Boeing knows about an issue and aren't taking the boldest possible steps to ensure the safety of passengers, then the potential reputational risk is even greater.

It has been done. It can be done.

“We’re asking our customers to ground the airplane as a precautionary measure. We have the utmost confidence in our engineers, processes, blah blah blah, and are confident that the 787 Max will be flying again as soon as the investigation is completed.”

Advil did this, and their brand was just fine, possibly better because they were aggressive about putting lives ahead of this quarter’s cash flow.

Advil pulling medicine is different than Boeing grounding planes. What if grounding planes cancels flights forcing passengers into cars? Should that factor into the decision to ground the plane?

That's a valid consideration, though I don't see how it's less applicable to medicine. What if someone who takes aspirin instead gets Reye's syndrome?

Investors say... SELL, SELL, SELL.

Investors also say, "Charge $900 for insulin," and, "All I want are dividends, I don't care if you're dumping pollution into the Love Canal.

Management's difficult job is to know when to say to investors, "Sorry."

I believe that the commercial jet industry works a bit differently. It seems that they just rely on the carriers to make that call, though I could be completely mistaken.

Having said that, this is a snippet from AVHerald's post on the crash (https://avherald.com/h?article=4c534c4a&opt=0) pointing to an AD that indicates an enhancement ("fix") and here's a link to an interpretation of that (https://forums.jetphotos.com/showthread.php?62381-Breaking-n...):

On Mar 12th 2019 Boeing issued following release with respect to MCAS, Lion Air Flight 610 and Ethiopian flight 302:

For the past several months and in the aftermath of Lion Air Flight 610, Boeing has been developing a flight control software enhancement for the 737 MAX, designed to make an already safe aircraft even safer. This includes updates to the Maneuvering Characteristics Augmentation System (MCAS) flight control law, pilot displays, operation manuals and crew training. The enhanced flight control law incorporates angle of attack (AOA) inputs, limits stabilizer trim commands in response to an erroneous angle of attack reading, and provides a limit to the stabilizer command in order to retain elevator authority.


The FAA says it anticipates mandating this software enhancement with an Airworthiness Directive (AD) no later than April. We have worked with the FAA in development of this software enhancement.

It is important to note that the FAA is not mandating any further action at this time, and the required actions in AD2018-23.5 continue to be appropriate.

A pitch augmentation control law (MCAS) was implemented on the 737 MAX to improve aircraft handling characteristics and decrease pitch-up tendency at elevated angles of attack. It was put through flight testing as part of the certification process prior to the airplane entering service. 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.

Boeing’s 737 MAX Flight Crew Operations Manual (FCOM) 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. In addition, it can be controlled through the use of the existing runaway stabilizer procedure as reinforced in the Operations Manual Bulletin (OMB) issued on Nov. 6, 2018.


This is an important point.

Boeing is being reckless with their whole business and showing bad leadership. Regardless if they are sure that there is no real risk with their planes; their reputation surely is at risk.

Well, they were rattled enough to postpone the global launch of their new 777X which was slated for this week.

That is even worse; they are sorta implying whatever is wrong with the max is also wrong with the 777x.

They need to ground the max so they control for how long for and what is needed to clear them.

I disagree. They’re simply showing enough compassion to know that it’s not appropriate to throw a part while 150 families are mourning.

believe he'd like a s/part/party/ in there.

That said, it's more realistic they're delaying it because they don't want the bad press of the 737MAX to bring down the announcement of the new plane.

I hope they are putting the safety of their passengers ahead of their reputation. Maybe grounding the plane is the right PR decision but the wrong safety-first decision.

Considering we don't yet have much information on the cause of the most recent crash this is a hell of an assertion to make. If they ground things at the drop of a hat that is also reckless.

They'll know in a couple of days what happened since they already have the recorders. With one crash every ~6mo (someone can crunch the numbers and get the naive probability of a crash per flight) and every pilot of a MAX8 now on the lookout for possible problems the public is not seriously put in danger by another week or so of these aircraft flying. Imagine if Boeing grounded these and it turned out the second crash was pilot error. That would be a footnote that would get 10sec in the news months from now. Do you want to be forever known as the guy who tanked Boeing's reputation over a false positive? That has costs to society too. And before you say yes remember that it's much easier to say you'll give your lottery winnings to charity before winning the jackpot.

The drop of a hat?? 2 plane crashes killing 346 people under eerily similar circumstances within 5 months is the drop of a hat?


I disagree that it's a knee-jerk reaction, drop of the hat, or whatever you want to name it. We are talking about hundreds of human lives. We are talking about an industry that consistently chooses safety above all else, regardless of profits and minor inconveniences. And for some reason that just doesn't seem to be the case here.

> Unfortunately it's impossible to have an adult discussion about that kind of thing on the internet.

So unless everyone agrees with you it isn't an adult conversation? Entire countries are grounding these planes. The evidence is pretty clear that folks are worried and aren't interesting in risking the loss of a few hundred more lives because a bit of money may be on the line, or there may be a minor travel disruption.

Edit: I see the original poster has since removed the bit about not being able to have an adult conversation on the internet. I quoted and responded to that before it was removed.

> We are talking about an industry that consistently chooses safety above all else, regardless of profits and minor inconveniences. And for some reason that just doesn't seem to be the case here.

Or maybe it is the case here. We all seem to think it's obvious Boeing should ground this plane and yet they aren't. I hope Boeing aren't idiots and are making their decisions based on engineering factors we don't have.

But if they have information that leads them to a completely different conclusion, why aren't they sharing it? I'm having a hard time coming up with a scenario where they have more confident data, but can't share it (or if not what, at least share that they have it).

The idea that at some point the additional cost of trying to save lives is more than the value of the life being saved is incompatible with the beliefs of many people. Yet that reality and trade-offs like that are all around us. For example, OSHA could decide that overhead lifting now requires a safety factor of 15 on everything (IIRC it's 5 but it's been awhile). That would probably save a couple lives because by starting off at 15 you could still have a safety factor >1 with totally clapped out equipment. Would that be worth it? This is the kind of dilemma that gets discussed in the "engineering ethics" course that most of the college graduates here had to take and I'm not going to expand on it because there's plenty of other people who have but the takeaway should be that there exists a point where the return on investment of trying to prevent life lost is negative depending on which externalities you count and how you count them.

Personally I agree with the airlines grounding the aircraft because the air-frame failure rate is too high IMO so clearly something is up with them. I fully disagree with the "every life is precious" + "OMG we have no idea what's going on" sentiment being used to justify that. That's now how you're supposed to make these kind of decisions, especially when the recorders from the second crash are in hand and we will soon have a good idea of the cause.

Based on what we know at present, the first crash would likely have been prevented had the pilots been made aware of the new possible failure mode of MCAS, recognized it and disabled the system, the steps for which are the same they've always been. Any 737 pilot not living under a rock is very aware of that new possible failure mode now. While crashing aircraft and publicity like this might not be as good as retraining it has likely accomplished a similar end so if the cause of these accidents is what we currently think it is then the press it's receiving will go a long way toward solving that albeit at unfortunately high cost.

FWIW I removed that sentence from my comment because I didn't want a self fulfilling prophesy but I've added it back to my comment because it mostly came true. No "I disagree because X" (where X is not an appeal to emotion). Just people mashing the "bury this" button and appeals to emotion. Basically Reddit sans the sarcasm.

You know as well as I that any discussion about trade-offs involving human life (or any other emotional topic) eventually just get drowned out by name calling and general bullshit and an adult discussion isn't really possible.

Your comments imply that the aircraft industry functions in a manner that allows for human life to be calculated as a tradeoff. This shows an ignorance on how aircraft is expected to function and the industry standards for aircraft development and engineering. Given that loss of life of paying clients is the worst-case-scenario of an aircraft it makes total sense for it to be treated with severity, entirely without bringing virtue into the discussion.

> Your comments imply that the aircraft industry functions in a manner that allows for human life to be calculated as a tradeoff.

It's true though, just like in any engineering discipline. If loss of life was 100% unacceptable then the only resolution would be to not fly any aircrafts. The fact that we still use flight technology is a tradeoff in itself.

Unpreventable loss of life may not be 100% unacceptable. But ignoring signs and allowing preventable loss of life is. Not taking action after having reasonable reason to do so is actually criminal negligence [0] in some cases.

> failure to foresee and so allow otherwise avoidable dangers to manifest. In some cases this failure can rise to the level of willful blindness, where the individual intentionally avoids adverting to the reality of a situation.

[0] https://en.wikipedia.org/wiki/Criminal_negligence

What's reasonable? Some people refuse to fly altogether due to the risks. Are they reasonable? I don't think so, personally, but it's not a black and white issue like you're implying. Every accident is preventable if you just demand less from the underlying technology.

Your comparison is exaggerated. Two crashes of the same model and similar circumstances in less than 5 months, for a model that's under 2 years old and only 350 built in total raises suspicions. It's not a good record. The very fact that the suspicion exists is enough to back up the reasonable claim. Whatever the problem is (design, pilot training, etc.) it's hurting this model and its passengers so it should be investigated without risking more lives. Precautions are always based on suspicions. Otherwise they're no longer a precaution.

With aviation experts, governments, and even airlines (bearing the costs) agreeing with the grounding measure I think I'm not too far off. The list in the article above just gets bigger. The current situation lends a lot of credibility to the idea that the plane might be to blame. Grounding them could be expensive. Not grounding them could be criminal. Which one would you choose if you had to?

Also this: https://news.ycombinator.com/item?id=19369485

I agree with you in this particular case. What I was arguing against is the grandparent's claim that the aviation industry doesn't make any tradeoffs involving human life. It is absolutely necessary for them to make such tradeoffs as I was trying to show with my hyperbole.

You're making discussion about 350 lives lost potentially due to design failures into discussion about statistics. Such a cold-hearted approach won't find you much support anywhere.

Clearly most people react very differently to this topic compared to you, even purely for-profit companies start to do so.

There are 350 737-MAXs in service

There's about 6500 737s, and a similar number of A320s.

Grounding 2.5% of the world's fleet of mid-size planes isn't really a medium sized wrench.

Personally I'll fly on the 98% of mid-sized planes that haven't had 2% of them crash in the last 6 months.

It’s a solvable problem in the medium term, but a real mess short-term if your fleet has a high proportion of 737 MAXs.

True, but that’s part of the risk equation of deciding to go for a monoculture in the first place (as with most business choices). There are benefits (ease of maintenance and training highest) that need to be judged against potential problems (like in this case where a model is grounded).

Even in my airline’s case, they’re not monoculture, but I’m booked on one of their longest routes. They can only sub another plane if they make a refuel stop (or so it seems by my estimation).

We’ll see what happens.

Which fleets do? Southwest and American don't, 5% and 2% respectively.

Norwegian is 11% and have grounded their planes. Air Canada 10%. China Southern 3%, Air China 3%.

FlyDubai seems the largest, with 14/62 planes (23%).

> haven't had 2% of them crash in the last 6 months

Wait, 7 (= 2% of 350) planes crashed in the past 6 months?!?

The sample size isn't actually 2... It's 2 crashes in tens of thousands of flights of the 737 across the multiple airlines that use the model.

However, that having been said, the crash rate is now very poor (by modern standards) for this plane model, and 2 is enough to raise some serious questions about mere coincidence.

Boeing's taking a real risk because a third crash of a 737 regardless of cause will be a long-remembered black eye.

The existence of a design flaw does not need any crash data to prove that it exists. It like saying that a software vulnerability needs to be proven by successful hack attempts. The issue exists regardless.

What we don't have data on is the effectiveness of recommendations designed to mitigate the risk. A repeated crash is evidence that the mitigation is not sufficient.

You have a poor understanding of stats if you think 2 is always a small sample size. In the case of theoretically rare events 1 event can be exceedingly significant.

The fact that airlines and governments are doing it anyway kind of says this is the right reaction. It's a precaution and you take it even if you don't have the full picture yet.

> People's lives are disrupted, sometimes catastrophically

Not unlike a what happens in a plane crash. As a passenger I'd rather pay more for a ticket or have a delayed/missed flight than accept the current risk of flying with this plane.

> The lives lost already are a sunk cost.

This isn't just cynicism or pragmatism, it's plain wrong. Another crash could happen at any time if the issue is indeed with the plane and your argument is "we can't bring the dead back so we might as well pile some more"?

>The lives lost already are a sunk cost.

You are either Autistic or you work for Boeing.

Personal attacks will get you banned here, regardless of how bad another comment is. Please review the site guidelines: https://news.ycombinator.com/newsguidelines.html.

If they ground the plane, maybe this allow the airline to cancel orders and get deposits back?

TFW when Indonesia grounds a US made aircraft type based on safety concerns! It wasn't so long ago that USA banned Indonesian carriers from flying into their airspace.

As a former commercial pilot, I applaud the individual countries and airlines that are enforcing a grounding pending the investigation. The two accidents just bear too many similarities to assuage all fears that there could be a specific problem with the aircraft.

Would you say that at this point it's starting to be a peer pressure issue? Once several national regulators ground the aircraft, if any regulator chooses not to and there's an incident then they'll be raked over the coals. Legally and career-wise, it's far safer for anyone in the hot seat to follow suit.

I daresay the pressure within the industry (plus fear of PR and legal repercussions down the track) may be playing a big part in some airlines and governments calling for the grounding. No one wants to be the guy to say "Oops" if the investigation shows up a critical issue with the plane (or worse, if another 737 MAX goes down the same way soon). As much as it will be a hit in profits to call a grounding, the alternative would be way worse.

(I am thinking too that if the investigators DID find a flaw in the aircraft type, the operators may have an avenue to claim compensation from Boeing for lost revenue and profits).

Personally, if I had to get on a flight tomorrow, and I saw it was a 737 MAX, I would be asking for my baggage to be unloaded and I would wait for another flight on a 737 classic, Airbus etc. And this is not just brand snootiness either - If new Airbus models had 2 crashes in a short space of time under similar circumstances, then I would boycott those until the officials have eliminated a flaw in the system as the root cause.

UPDATE: Just heard that our local aviation authority (Australia) has banned the MAX from entering or leaving the country. There are a few stuck in Sydney (Fiji Air and Silk Air I believe) that will have to stay on the ground until further notice.

Some background: 3 months ago, also discussed on HN, in the wake of the previous 737 Max crash:


"Boeing Withheld Information on 737 Model, According to Safety Experts and Others (wsj.com)"

And user Neracked remembered there Feynman's ending of his text in the Rogers Commission Report, 1986:

"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled."


(https://en.wikipedia.org/wiki/Rogers_Commission_Report investigating 1986 Space Shuttle Challenger disaster, related to how the managers then were responsible)

This is really troubling.

I have a flight in a month from NY to Cali on Southwest and they use that same plane (according to a quick Googling at least).

Am I crazy to think about cancelling the flight or trying to use a different airline with a different plane?

I'm going to wait to see what the FAA has to say before making a final decision. I don't keep up with the airline industry, but hopefully they aren't too corrupt (aka. profit driven).


I just discovered https://www.seatguru.com/. It's a site where you can pop in your airline, flight date and flight number (no sign up required) and it reports back which plane is being used in the flight.

In my case it is the 737-700 and 737-800 (I have 1 connection) which I think are different planes than the MAX?

In any case, if you're flying in the near future I recommend checking that site out. I just wonder how accurate that site is (it seems legit from an outsider's POV).

I don't think you are crazy.

At the end of the day, you only have one life, it's not like you get to hit reset while the airlines say "my bad".

TBH, it's a really bad look when US carriers are insisting that "it's fine, it's all fine" while other carriers are grounding out of an abundance of caution.

If you know you are flying on an 737 NG (700 and 800 are both NG) and not a MAX model, then I think you may be overreacting. The 737 NG has just about the best safety record of any plane ever.

If I were flying on a MAX soon, I'd think about it, for sure, that's human nature. But try to remember that it has had a couple hundred thousand uneventful flights in addition to the two crashes.

Yeah after finding out the exact model number I'm not going to cancel or switch airlines.

I didn't know about the seatguru site when I first replied.

Well I don’t care to speculate but the first officer had only 200 hours of flight logged and the captain had over 8000. A lot of captains will let the less experienced first officer fly take off and landing if it’s favorable conditions and easy terrain to give them more experience. I don’t know who was flying the plane but it certainly could have been the fo because it was vfr conditions and seemingly favorable terrain. As to your flight you should probably be fine as there is a us rule that the fo needs to have 1500 hours to be qualified. That coupled with the fact that the pilots are now keenly aware of the failure mode of the 37 max means you are probably fine.

> A lot of captains will let the less experienced first officer fly take off and landing if it’s favorable conditions and easy terrain to give them more experience.

For US carriers, alternating legs between PF (pilot flying) and PM (pilot monitoring) is standard practice as dictated by the carrier's own Flight Operations division (aka, "The Flying Department").

In the event of an emergency it'd be expected (if not mandatory) that the PIC (pilot in charge, e.g. captain) to immediately become the PF. The standard call-out for the role swap is "MY CONTROLS" or "MY AIRCRAFT"

Case in point: US1549, the Hudson ditching, was being flown by the F/O. After the bird strike and loss of engines, Capt Sully called "My aircraft"; the F/O replied "Your aircraft", effecting the swap of roles.

(me: US aircraft dispatcher in a previous life xD )

I would certainly cancel. Boeing still has not applied a software update, and pilots were already aware of the 737's failure mode, the 2018 crash! The FAA is being protective of US industry.

Not all 737 models are affected. the -700 and -800 have excellent safety records; among the best of any airframe. These issues both happened with MAX (MAX 8 iirc) airframes.

SouthWest does fly 35 MAX8 airframes it appears. [0]

[0] https://en.wikipedia.org/wiki/Southwest_Airlines_fleet#Curre...

I wouldn't be too worried. Keep in mind that the pilots have much more risk exposure than you do and as such aren't going to sit back and watch. The US licenced pilots are very aware of the issue and know what to do in the event of a trim runaway. Even the solution itself is very simple. Yes, it's a risk but statistically it's very low and at this point, well mitigated.

Your carrier tells you which type of plane you're on. As you've noticed, there are also other sources for this information.

Most of Southwest's fleet are standard 737s. If you're not that familiar with the various models, it's probably not worth making a rash decision over.

Regardless, this will be sorted out, one way or another, in a month.

I did care enough to ensure my Southwest flight 2 days ago was not on a Max, though.

TBH at this point everyone should do it, since it will be a nightmare flying on these, until the investigation is over. I can’t imagine how the crew feels when assigned to such a fight in these circumstances.

The current theory of "why" is that the new system should work automatically so there's no need for retraining, but if it goes wrong the pilot can disable it; but since there's no retraining, the doomed pilots didn't know why the planes were doing what they did and how to disable it.

If I were a pilot and got assigned the same model, I would make sure to learn the procedure to disable it. And make sure the procedure really works, although how would I do that, can I ask Boeing? Since it's software, what other variables did they forget to include in their testing?

The pilots are required to, by memory, know when this particular situation is happening and how to disable the system. The checklist is the runaway trim checklist, to turn the system off the pilot flips switches next to the trim-wheel, which moves with the automatic trim to visually indicate trim adjustments. This is not new to the MAX, only MCAS adjusting the trim is new to MAX.

It's already been established however that if the pilots follow the original checklist then they would be disabling it as part of those steps. With the first crash it was decided that they quit following the steps and kept fighting the stick until it was too late.

When customers start complaining they'll ground them I think

Customers are already demanding information about the plane assigned on their flight.

If you look at Southwest's Twitter feed, it's in full spin mode.

Oops. Germany, too, follows suit and closes their airspace for the MAX.


Lots of comments asking why not ground these planes, so let's just for a moment imagine some reasons why that may not be the best decision if your goal is safety first. First, we know that any decision that forces passengers from flying to driving will likely lose more lives, just due to the inherit risk in flying vs driving. So it's possible that grounding the plane will cause cancellations and force some passengers into driving, especially in the US. Second, perhaps Boeing already has some advance information pointing to a different culprit than MCAS. Third, an MCAS failure need not doom the flight if the pilot responds correctly. Perhaps US carriers feel that their more experienced pilots can deal with an MCAS fault. Fourth, maybe US planes are better maintained and Boeing hasn't seen any MCAS/AoA faults on US planes.

These are all guesses on my part. I don't know. What I do know is that the FAA and Boeing have way more information than any of us, that this situation is complex, that there are factors likely none of us have considered, and that we're all pretty terrible at assessing risk.

Another 737 Max crash is a nightmare scenario for Boeing. If they aren't grounding this plane, it has to be based on something we don't know. Consider that grounding the plane might be the right PR decision but the wrong safety-first decision.

>First, we know that any decision that forces passengers from flying to driving will likely lose more lives, just due to the inherit risk in flying vs driving. So it's possible that grounding the plane will cause cancellations and force some passengers into driving, especially in the US.

Well air travel is safer than driving in aggregate, over decades, across hundreds of models of cars and dozens of models of planes.

Even though Ford cars on the whole are quite safe, the Pinto was a death trap. Likewise although Boeing planes are safe on the whole (the regular 737 is very safe) this model could be a death trap. I disagree with your claim here. Two crashes in under 6 months is an abysmal safety record.

Right, that's an example of Simpson's paradox (I think).

I agree two crashes in six months seems abysmal, but it could also be an awful coincidence with different factors at play. If it's so obvious that Boeing should ground this plane and they aren't, might it be due to something we don't know?

Yes, this could be another Challenger-type situation of executives overriding engineers, but the incentives don't make sense to me for that to be the case.

Anyway, I've played devil's advocate enough here. I'm just trying to understand the situation too.

Another possibility is that the 737 MAX 8 is, just like the rest of the 737 fleet, an outstanding performer with one flawed subsystem, the AoA sensor. The FAA and the aviation industry in general has been very excited to deploy these AoA sensors; they've reduced regulatory hurdles across the board to get AoA sensors of all different types installed and retrofitted into airplanes of all sizes and shapes. The reworked part 23 rules were first put to work on AoA sensors, and the expansion of AoA deployment was part of the drive to do the part 23 rework (which has ripple effects across the entire industry, for the better.)

But when you push new technology, inevitably there will be unexpected failure scenarios. This may be one of those, with a particularly catastrophic series of events.

It is a simple fix, and Boeing is already rolling out software updates to manage this failure scenario. If it does turn out to be the MCAS/AoA fault, it would in fact be the best scenario, because it's already fixed.

Thanks for the info. I guess the question for me is: even with a bad AoA sensor and the current MCAS behavior, can it be safer flying a 737 Max than whatever equipment I'd end up on if the 737 Max were grounded until the s/w update is deployed.

I seem to recall after the MCAS came to light as being involved in the Lion crash, some folks here were arguing that there was no way that exact crash would happen again because all pilots would now be aware of that failure scenario. And yet here we are. Unless the Ethiopian plane crashed for another reason entirely.

Well yes, although it's possible the Ethiopian Air pilots haven't seen that memo. If I recall correctly, a fast remediation suggestion was to switch off all avionics power. As a pilot myself, I would be deeply reluctant to do such a drastic move, especially in an emergency. With the airplane in an overpowering dive, removing all instrumentation in one kill switch move just doesn't seem like the right thing to do. While I don't know the 737 MAX 8 electrical layout, in small planes that would also kill the radios, transponder, and navigation systems, possibly also flap controls, lighting, and some direct instrumentation. Such direction would have to be very strongly communicated if it were a viable escape from the MCAS/AoA failure.

The first good points I heard in favor of not grounding the plane. Thank you for the insight!

Several more airlines grounded their 737 Max fleets today, but none of the US carriers did.

Nor any European carriers, nor EASA. I also notice that Canada is not interested in grounding them at this junction. I'd imagine that US pressure is preventing the Europeans and Canadians from grounding them. At least so far anyway.

CASA (the Australian regulator) just did it https://mobile.abc.net.au/news/2019-03-12/boeing-737-max-8-s...

UK CAA just grounded 737 Max, and not permitting overflight either.


"The UK Civil Aviation Authority has been closely monitoring the situation, however, as we do not currently have sufficient information from the flight data recorder we have, as a precautionary measure, issued instructions to stop any commercial passenger flights from any operator arriving, departing or overflying UK airspace"

Banning overflight seems like a politically-motivated overreaction. Both incidents took place shortly after takeoff, and there's no current reason to believe the planes aren't safe at cruising altitude.

Dublin airport in Ireland is about as far from UK territory as both of the 737 MAX's were from their respective airports when they crashed into the ground.

It would be an unfortunate complication for the current discussion on a hard Brexit potentially happening within 3 weeks if the UK needed to work out what to do with an airplane strewn across that border on top of everything else.

Norwegian Airlines / DY just grounded their 737MAX, too.

Presumably as UK airspace was just closed to them.

Anyway - the ball is rolling; it is much easier being the [n]th airline/regulator to ground it than it is to jump first.

Maybe it's a confidence thing. Maybe small operators from these regions feel less supported/confident than their European or American counterparts. This might be a very pessimistic approach but I suppose a lot more phones go ringing when someone from Southwest or RyanAir calls and asks:"Yo, what's up with my planes?".

That just makes it sound worse. Why should Norwegian get better support from Boeing than Comair? While I have no doubt that FAA or EASA would have reacted with more expediency had the crash occurred in their jurisdictions, it scares me to think that Boeing treats its customers differently, depending on whether they are Western or not.

the treatment is probably proportional to how many planes they order. Im sure if ANA or Singapore Airlines have some issue with their 787s, Boeing would respond immediately. Has nothing to do with western but everything to do with money.

See Lauda 004 for how Boeing treats a small Austrian airline. They only responded once the CEO (Niki Lauda) forced their hand by saying he would do a public stunt if they didn't respond.

Exactly. I didn't mean to imply that Boeing is discriminating based on the locality of an airline, but there is no denying that there is more money to be earned in places other than Indonesia or Ethiopia. That probably does reflect Boeing sells and airlines buy aircraft. This is just a strong hunch, I have no empirical evidence.

Don't get me wrong, I don't believe Airbus is a charity in any way and their sales are different.

> Im sure if ANA or Singapore Airlines have some issue with their 787s, Boeing would respond immediately.

SilkAir, Singapore Airlines's regional subsidiary, is flying the 737 MAX 8 too.

I think the idea is that Borwegian buys a lot more planes from Boeing.

But it isn't just operators. Singapore has banned all flights coming in and out. This is a busy, world-class airport (at least for passengers, but it's hard for me to imagine something that's run so smoothly at that scale for passengers would be a shit show for operators).

I do not think that RyanAir has many 737 Max jets. Ryan Air mostly flies with 737-800, but they want to migrate to 737 Max over the years:


They try to only fly with a single jet or a maximum of two, to keep the costs down.

As per your link and also Wikipedia, Ryanair doesn’t operate any 737 MAX yet, but have placed orders for them.

There are very few of these in Europe currently. The UK has just grounded them, though.

I don’t think that is true. Even if there is a pressure, most probably it is only about not going public about it.

This accidents won’t harm Boeing reputation. The only thing that might hurt it is more accidents or even worse, putting pressure on Airlines to use it during investigation. So even if there is a pressure, it will be only about not going public with anything related to grounding 737Max.

Anything else would be stupid.

How do you not go public about grounding it? Due to regulations you can't operate a scheduled flight without disclosing the aircraft type, so the moment you start operating with a different aircraft, everyone knows, even if the airline did not release an official statement.

You'd also have to cancel a lot of flights. Airlines don't tend to have a huge reserve of airworthy planes sitting idle as substitutes in case their regular fleet gets grounded.

Airlines can still do it without making a public announcement about it. For new schedules itbis easy, and for existing ones just an update on bookings or reschedule. It would take sometime for the news to go out and yet many wouldn’t consider it a grounding.

That’s way better than public announcements that gets picked up by media.

How would it take some time for news to notice? In the wake of this latest crash, news media and amatuers alike are constantly paying attention to what airlines with the 737 MAX-8 are doing. If they notice that airlines are starting to reschedule their flight plan to use other aircraft than the 737 MAX-8, the news will be out instantaneously.

Indeed, if they do it in secret (attempt to anyway), it will probably be a lot worse than a public statement. I just don't see how you can hide that major a change (I think flight plans are public anyway) without someone noticing immediately in this day and age.

How can grounding not be made public?

>This accidents won’t harm Boeing reputation

It's already harmed and they longer they wait to take action the worse it will get. Their stock price is plummeting as we speak.

If you guys are interested in some close-to-the-details reporting on individual crashes, http://avherald.com/ is an excellent resource. For some reason I couldn't find the specific crashes related to the 737 Max in their logs though, I didn't search very very thoroughly though. It may only show certain carriers.

You can search for "B38M". The top two are the Lion Air and Ethiopian Airlines crashes.

UK grounded all Boeing 737 Max


What would be the quickest way for me to check which aircraft a flight I want book is being carried out with?

Go to any flight radar (online, google etc) and look up the previous flights with the same flight number (letter/number combo) as they usually mention the type. 99.9% of the time the plane is the same.


Doesn’t this just damage the brand of the other 737 Boeing has, that from what I understand has a terrific record? I’m guessing most consumers are going to be apprehensive if they’re flying on any kind of 737. Whereas, they pull the Max and passengers would know that they're not on the troubled plane.

No, for the very reason you state.

Not sure I follow. What I’m saying is most people won’t make the distinction between the different 737s.

I thought it was well-known that 737s have been flying for decades, and an issue with a 737-Max would, necessarily, be about that specific plane.

I certainly don't expect people to grasp the nuance between the 737-max800/max900, if there is one in this regard.

I see. I mean, I actually enjoy flying despite the hastles of getting to and from the plane. But, I’d rather not take my family on a Max. However, when I hear 738 8 Max and I see 737-800 on my ticket, I immediately wonder if they’re the same thing. The presence of articles like this make me think this is a pretty common concern:


And this is despite the fact that I’ve always felt safe on Boeing planes because they’ve historically had such a great safety record.

I would assume this is gonna have a negative impact on the 737 line as a whole, since people tend to read just the headline. Whereas, had they immediately grounded the Max, there’d be no question; as a passenger you’d know you weren’t on the troubled plane, because they grounded that one.

It’s like when Romaine lettuce gets recalled; a lot of people just stop buying lettuce because they’re just not sure which kind it was that got recalled.

While it could certainly be the same issue, I've seen enough airline crash stories to know that your first assumption can be wildly incorrect. Typically people who investigate these things try to have no pre-conceived notions of what it could be, not much different from debugging a software crash.

Boeing says they'll issue a software update in the coming weeks. Is that what the problem was? https://boeing.mediaroom.com/news-releases-statements?item=1...

InternetofShit is starting to kill people..

France too.

There are reports that this aircraft was trailing smoke and making unusual noises before it crashed.

From my understanding of the earlier crash it was a combination of the pilot fighting an auto-trimming system and I'm not aware that was smoking on its way down.

This would seem to be a different type of incident which just happens to be in the same model of plane.

There's also the fact that witnesses will tend to say all sorts of weird things that get proven false in video footage later on. So I personally would be cautious about believing the smoke and unusual noises.

stall could lead to backfire, maybe that is what seen

It sounds like no one system of keeping the plane level is fool & error proof.

OK, this might be a stupid idea, but what about a simple old spirit level, a fancy oil based one that will never freeze, mounted to the side of the cockpit to give the pilots a emergency true level backup when all else fails?

The instrument panels on old beater Cessnas, Pipers etc. have a 'slip ball' on the turn indicator which is basically a small ball in liquid. But that shows if the plane is laterally out of balance during a turn.

It is about the only gravity based instrument on the aircraft (because ideally, you would want to keep a steady 1G straight towards the floor of the plane during a turn for passenger comfort).

All other instruments that relate to orientation are gyroscope based, so they constantly reference a point in infinite space. When you are being thrown about in turbulence, or a tight turn, gravity based instrumentation will be all over the place and give false readings.

Pretty much exactly why IFR (instrument flying) rated pilots are trained NOT to rely on the inner ear balance systems to know if they are flying straight and level etc. because the inner ear fluids can be easily tricked by standard flying manoeuvres into thinking you are in a screaming right hand dive when you are in a gentle left hand turn (if you don't have a visual reference to corroborate).

It'd work fine if the plane was stationary but the moment you have any acceleration, you couldn't trust it.

During one train travel I've watched one window filled with a few inches of water between the two glass planes. If you'd trust that one alone, the train went more than 45 degrees up or down when it was actually traveling on the flat ground, but changing the speed.

Are you just copy/pasting this across different discussions on this topic? While I personally like the proposal (I am no pilot so it may be a dumb idea to a professional), c/p the same post is just noise.

Sorry, just trying to maximize the chance of getting an answer.

So, basically the same approach that spammers use - maximizing your gain while inconveniencing everyone else. I hope you're proud of yourself.

Well, what does he have to lose?


Look up the pilot running a few different level meters when debunking a flat earthers on YouTube. On mobile but will see if I can link later. Normal levels don't work well at all on planes.

I would rather expect the anti-stall system to be based on a speed indicator rather than a level indicator. Though not an aviation specialist.

Beyond the point, made by others, that a spirit level will not give you the airplane's attitude (on account of acceleration), it is also the case that the airplane's attitude does not tell you the angle of attack, which also depends on the airplane's vertical speed with respect to the airmass. Pilots-in-training are taught not to rely on the airplane's attitude (normally judged, in visual flight, by the position of the nose or top of the instrument panel relative to the horizon) as an indicator of whether a stall is imminent.

In a steady state, and for a given wing configuration (flaps/slats/spoiler positions), there's a causal relationship between angle of attack and speed (which also depends on air density, aircraft weight and load factor (how many gs you are pulling)), such that the indicated airspeed (which measures ram air pressure in a pitot tube, and fortuitously cancels out the density dependence) has historically been the proxy for angle of attack - and, at least in small airplanes, it still is.

Even small airplanes often have a separate stall warning device, which is triggered by the movement of the leading-edge stagnation point (where the flow divides between going above and below the wing) as the angle of attack changes. In its simplest form, it is operated by a small tab which is flipped up when the stagnation point moves below it.

I think it needs to be both - air speed and angle of attack.

Stalls can be induced both ways - angle of attack and/or speed. Usually a combination of both.

Firstly, let's note that the cause of the Ethiopian Airlines crash has not yet been determined.

In the case of the Lion Air crash, the problem was not that the crew were unaware of the airplane's attitude (it was daylight in good weather, and they also had functioning airspeed indicators), it was that the control system kept resetting the longitudinal trim incorrectly in response to a faulty angle-of-attack sensor, and the crew did not follow the procedure to disable it from doing so.

Guidelines | FAQ | Support | API | Security | Lists | Bookmarklet | Legal | Apply to YC | Contact