Hacker News new | comments | show | ask | jobs | submitlogin
737 MAX crashes “linked” by satellite track data, FAA says (arstechnica.com)
228 points by close04 2 months ago | hide | past | web | 150 comments | favorite

Many aviation enthusiasts / pilots first go to is to have a look at the flight data - usually available on FlightAware / FlightRadar24 and a few other websites, plus LiveATC usually can provide recordings of the flights communications to towers as well.

Most immediately saw parallels with the Lion Air crash - but as always, we as laymen should refrain from coming to conclusions until after a thorough investigation has been completed.

The fleet has been grounded, and reports / data will slowly trickle out as more conclusions are made.

It is/was a real stretch to draw any parallels based on the amount of ADS-B data we got out of FR24. The plane went out of range of the nearest FR24 ADS-B receiver just a few minutes after taking off. People see what they want to see.

It sure is an impatient world we live in. Probably attributable to the Internet, our insatiable need for more information NOW. Everyone ripping on the FAA for not making a grounding decision until yesterday, even though the crash itself happened just four days ago.

I think the Internet gives us the tools to discuss and learn and collaborate, rather than read the newspaper, watch the news, and think, "okay I'll just with until tomorrow's paper arrives to learn more."

Who are pre-Internet people going to discuss it with? A handful of people at the dinner table or at work?

It's not about impatience, it's about opportunity.

I guess we're lucky that Aireon's ADS-B satellite constellation was completed in February and captured this data [1]


There was quite a good analysis of that data in the NYT. Not sure it's that much of a stretch https://www.nytimes.com/interactive/2019/03/13/world/boeing-...



"Why Investigators Fear the Two Boeing 737s Crashed for Similar Reasons (nytimes.com)" (18 hours ago)

The data already available is quite precise. The Ars article is showing less precise data than the NY Times.

I rip the FAA for that. The level of air safety we have is because we have traditionally protected it fiercely. Within minutes of the second plane going down, the type should have been grounded until the FAA could figure out whether they were related. If not, they can unground them later.

There is a good reason we teach kids the allegory about the boy who cried wolf. If the FAA panics that easily they will destroy their creditability just as quickly as if they take too long. If they really did get new evidence yesterday and it prompted their decision, then I think they deserve more credit than the other world agencies that freaked out in a matter of hours. I want our regulators to be cold and analytical.

It is not panicking or freaking out to err on the side of caution and ground flights.

In fact it seems quite prudent for a regulator to do this.

> It is not panicking or freaking out to err on the side of caution and ground flights.

It can be, though.

There is a risk inherent to air travel. The safest thing to do would be to ground all flights of all aircraft permanently.

That wouldn't be prudent, though, because we can mitigate the risk until the benefit of air travel outweighs the risk of dying during air travel.

The prudent thing to do is to carefully evaluate the risks, and make a determination when the risks become too great.

“Panics that easily”? With two aircraft going down? If this was the criterion, how many such false panics would have happened in the last 30 years?

Look up any given commercial airframe and you will see multiple crashes.

Literally every one would have been grounded had the FAA grounded the type after 2 accidents.

I agree. I have qualms about the process, but I'm always nitpicky about various things. Boeing was far too involved in this decision matter IMO for example, but that's mostly an issue of optics.

Overall, I'm pretty happy with what I saw out of the FAA. It just seems like the FAA may have gotten the data last. Canada got it before we did. The EU got the blackbox first, so once they looked at the data, they banned the plane. China's response may have been preemptive, since there's no way they could have looked through the data at that speed.

Perhaps we should be pissed off at getting the data-last. But that's hardly the FAA's fault (maybe a State-department thing). In the future, Boeing needs to at least appear more neutral and less like a lobbyist when these events occur. There's significant distrust in our system these days, our regulators need to understand what it looks like when they're talking with the companies who make the plane before getting the black box...

It just seems like the FAA may have gotten the data last. Canada got it before we did.

Nope, the FAA had the data before the Canadians.

To be clear, Flightradar24 and other ADS-B-based online services do not provide enough data to come to a meaningful conclusion about these kinds of accident. The resolution is often too coarse to even see how quickly a plane would've pitched down, assuming it did so quickly.

Well, the FAA here just drew this conclusion based on ADS-B data picked up from a satellite, so I'm not sure how you're getting that idea.

At least, in areas where such sites have good coverage they may actually get closer to the ground data than the satellites are capable of picking up.

I don't mean to dump on doing a quality analysis, just that the quality of data is not as drastically different as you're suggesting.

Not just the ADS-B data, but also from physical evidence collected from the wreckage.

Online services actually do have the data available, just their online graphing is a smoothed out version of the data.

Generally data is received every 5 seconds. In cases such as Lion Air, they downloaded all the granular data from nearby receivers and provided some analysis in their blog.

They also made available the raw data for the public to download:


So they not provide? Not collected? Or is this kind of data not even broadcast in the first place?

This data is actually gathered by hobbyist and you can be a part of their network all it costs is about $25 for an ADS-B USB adapter. https://www.flightradar24.com/build-your-own They also offer free membership (499/yr) if you share data.

Every flight broadcasts this data kinda like GPS and all you need is an antenna to receive it. In fact the tracking is basically done via ground-based GPS(ADS-B) by measuring the time delays between different receivers in the vicinity. The problem is that there aren't many hobbyists in those parts of Africa so coverage is sparse. In America, its pretty spot on in most locations. A USB adapter can surprisingly pick up planes as far away as 400 miles.

If someone wants to do this, for the more technical audience there is a selection of better (but still pretty cheap) hardware available e.g. from


E.g. you can get an SDR with built-in ADS-B specific low-noise amplifier and SAW filter also for $25. (This can't do general purpose stuff though, unlike the one linked by parent.) Or you can get their general-purpose SDR and their broadband LNA for $40 total.

>by measuring the time delays between different receivers in the vicinity

No, position (likely received from plane GPS) is just openly transmitted in ADS-B frame.

So I guess the newly released satellite data was because nobody was running (enough of) these dongles where these incidents occurred?

> "we as laymen should refrain from coming to conclusions until after a thorough investigation has been completed"

People say this, but why? It seems to go against human nature. People love to speculate based on limited information and/or understanding.

Here's one example: https://en.wikipedia.org/wiki/Sunil_Tripathi

Being skeptical and keeping onself safe is fine, but things can go wrong if people are trying to falsely act like experts.

Sometimes even experts have a hard time distinguishing between relevant and irrelevant facts. Let alone normal people with no formal training in the field, no practice, and no evidence.

I blame reddit for this one.

Many reasons - the main one being drawing improper conclusions from the minimal data set available and passing them around as factually correct.

Speculation is fine, it's when someone is on Fox News as an Aviation "Expert" claiming that the plane was struck by an angry Zeus's lightning bolt, which many segments of the population will believe, that's when we have problems.

> People say this, but why? It seems to go against human nature. People love to speculate based on limited information and/or understanding.

We should resist that part of our nature. It is not rational.

Not saying I disagree (I tend to favor rational behavior myself), but this sounds like a dogma.

What evidence is there that only acting rationally is "better"?

Speculation is fine.

Concluding things off it is not.

That is true. I didn't read carefully enough.

This data's been available for several days at the least, right? Are they just trying to come up with an explanation for why they now support a grounding that they opposed yesterday that isn't "the President told us to"?

I'd argue yes.

It is identical data from ADS-B that we've had for days. People keep reiterating their "verified" line, but that had no basis when they said it, repeating it doesn't add to its legitimacy. The data today is the same data we had then.

It is essentially a way to ignore the data until it is politically expedient.

I was unaware that the president was involved in the decision making process, do you have any more details on that?

There's zero evidence so far that Trump had anything to do with that. Certainly he shouldn't.

But of course, we should have a fully-functioning and fully-staffed FAA, too. But we don't, because of Trump intentionally hamstringing it, and because of antics like trying to get his personal pilot named head of FAA when he came into office.

> Certainly he shouldn't.

Don't think I agree with this. The president shouldn't have to be involved. But if the FAA is acting in a bone headed manner, the president, as the head of the executive, is the check & balance that can get involved and fix the problem. Likewise the president is the one ultimately responsible to the people for the FAA's actions.

We don't know what extent Trump influenced the decision, but he was certainly involved, he made the announcement after all [0].

[0] Announcement https://www.youtube.com/watch?v=fs3NlxY5-iU

You've misused "checks and balances" a bit there, which generally refers to the rock-paper-scissors way in which the three branches of government (executive, legislative, judicial) are prevented from amassing too much power. As the FAA is in the executive branch and the president is directly in charge, it's not really a "check and balance" in that sense.

Checks and balances is a more general term than something describing the 3 branch system. A classic example within one branch is requiring both the senate and house to pass a bill.

To the extent that you think the FAA is actually serving as an extension of the will of the president you're right that I misused it, but I don't think that describes reality.

John Dunkin is the pilot you refer to. Do you think that he should be excluded from the job based on his Trump affiliation - or are there specific things he lacks that would mean he would be unsuitable for the job?

It appears that Mr. Dunkin has decades of experience as a pilot and has no previous affiliation with the FAA.

Decades of non-management experience in the same field qualifies you to run a 30,000 employee agency?

I've got decades of non-management software dev experience, perhaps I should be in charge of Microsoft?

Good point. And I think that is an important consideration.

However, to be clear, he does have smaller scale management experience - most likely consistently, but at the very least during the Trump campaign.

Perhaps he would be wrong for the job, but certainly there are examples of both experienced and less experienced/inexperienced persons doing awful jobs at the helm of agencies, companies, and even countries.

I would also add that being in charge of such a massive organization often means you do not get to make off the cuff or unilateral decisions so easily as you would, say, at a 50 person organization. You do certainly get to steer, but there are many other hands on the wheel.

As for you being CEO of MS, Satya is doing a decent enough job + I know nothing of your background and you come off as under confident in your ability to do the job. So I'll go with no :p

He lacks any kind of management experience.

Claiming an airline pilot lacks "any kind of management experience" displays a significant lack of understanding of the job of an airline pilot.

My understanding is, the president can’t order the FAA head to do anything. But he can issue an executive order for something to be done (ground a certain plane). That’s what I read what he did. BUT I tried looking up the executive order; couldn’t find one on federalregister.gov.


I doubt you actually read that. There was no reporting in the mainstream press of any executive order.

> I doubt you actually read that. There was no reporting in the mainstream press of any executive order.

This is incorrect. Simply Googling '737 max executive order' turns up multiple hits. This doesn't mean there was an actual order, however.

[1] https://www.google.com/search?q=+executive+order+737+max

Maybe he thinks if the executive issues an order, that is an executive order? There’s a chance I believe that with this administration.

There definitely wasn't an executive order, as is made crystal clear if you actually click through on a few of those hits.

It's political telephone. There was a widely-circulated story yesterday that Trump grounded the plane. Verifying before sharing is not as common as it should be.

It's interesting to note that, as emotionally salient this is for HN, in terms of significance compared to other problems out there it might be lower.

It's a bit of a flaw in human nature that easily-pictured problems scare us much more than abstract/distant problems.

Is it silly to press for a moral value of striving to make our morality align with numeric measure of significance rather than sensational emotions?

I think this 737 MAX issue resonates with the HN crowd because, along with the emotional factors, it’s a high-stakes technical problem.

The two fatal crashes were caused by an interplay of hardware, software design, and human factors, and studying things like this is fascinating to those of us who are interested in building systems so that catastrophes don’t happen.

It's a high stakes technical problem that is caused by not addressing technical debt - something that the many of the HN readership sees on a daily basis in other domains.

MCAS was created as a way to compensate for instability caused by strapping large engines onto an aircraft not originally designed for it, as opposed to doing a redesign.

Also there's the "sales/business people made the problem worse" angle as well that developers just love.

But there's also risk in designing a whole new plane, which had been Boeing's original plan. I'm not convinced MCAS is the wrong engineering decision. And who's to say a new plane wouldn't have a similar type of pilot assist system... the trend is in that direction.

Ok but the implicit assumption here is that a new design would not itself include all sorts of engineering trade offs between systems, maintenance, and pilot training, when in fact it would. The 787 was a ground-up new design and yet holds the distinction of the most recent previous instance of a full model grounding, over battery issues.

Iterating on a proven airframe has a lot of advantages for aircraft design and it is common in the industry.

I think it resonates with the HN crowd because many of us are on the 737-800 when we are on the nerd bird and many other Southwest flights.

> along with the emotional factors,

It's also entertainment in the same sense as catastrophe movies.

People love catastrophe and ignore larger problems all the time. During the 2017-2018 flu season, almost a million people were hospitalized and ~80,000 people died from the disease (1), a record high and a huge burdon on healthcare for everyone sick or not, yet we aren't getting 2-3 threads a day on influenza popping up on HN like we are with these 150 or so tragic deaths. Maybe part of it is who died. In the case of this flight, it was people affluent enough to afford jet travel. The news is filled with stories of their lives cut short and the tragedy of it all. In the case of deaths from the flu, it is often the old and those in poor health like the homeless who die from the disease, an invisible population for most people. We wont be seeing any articles in national news documenting the lives of those 80,000.

1. https://www.cdc.gov/flu/about/burden/2017-2018.htm

> "~80,000 people died from the disease"

This number sounds highly questionable to say the least: https://www.cdc.gov/flu/about/burden/how-cdc-estimates.htm

With no way to compare it to a gold standard how could anyone know how accurate it is?

The point is that it's a lot more people than a couple of plane crashes.

Not sure if I know which thing you mean. You mean plane crashes themselves (which kill far fewer people than the cars people drive every day), or this new "link" between the two crashes (which I agree seems spurious at first glance but they may yet confirm it)?

If you do that last thing, you may be a psychopath.


The basis for the “trolley problem” is precisely how you handle accounting for the numeracy of death versus the emotional involvement and personal culpability.

People who rationally perform cost benefit analysis about lives and well-being seem to have more psychopaths: see CEOs and other leaders. This isn’t necessarily bad, but it’s worth noting.

How is it we have such precise satellite location data on these crashes - but MH370 can just disappear.

The Iridium Next satellite constellation is new. SpaceX just launched the final 10 satellites in January 2019. Even if MH370 had their transponders turned on, it wouldn't have helped.


It was my understanding that all/most/all-controllable radios were shutoff at some point. There was some maintenance data from the engines that factored into the search location, but otherwise it wasn't transmitting anything.

I havn't followed very closely, so take that with salt, but it's a starting place if anything.

A flight data recorder provides a lot of information. https://en.m.wikipedia.org/wiki/Flight_recorder

We could stream this information via satellite uplink. Instead Radar and transponders is used to keep a close enough location to make recovery generally strait forward.

It’s really turning off the transponder while over the middle of the ocean that’s the issue for MH370.

It's my understanding from various reporting I've heard on this subject that the location data that is the subject of the OP is in fact data that is reported live via satellite comms, not data that has been retrieved from the FDR.

I am talking about a difference in resolution.

Locating a crash within 5 miles makes recovery of the FDR strait forward. A location update every 30 seconds easily provides that and looks like a lot of data. But, to really reconstruct a crash you need a lot more data including control surfaces etc, which is where the FDR comes in.

Didn't you read the part about the transponder being switched off?

Please see the "In Comments" section of https://news.ycombinator.com/newsguidelines.html. Writing "The transponder was switched off" would contribute the same substance to the conversation but without the insinuation.

My understanding is this was more precise data than ADS-B. Perhaps I’m wrong - I’m legitimately asking.

It says the damaged flight recorder was sent to France. Do they have a better recovery/repair team than, say, the US’ FAA and NTSB, or is it more likely just because France is much closer to the crash site?

I've read that they don't want to send it to the USA because of the possibility of Boeing to unduly influence the investigation.

http://fortune.com/2019/03/13/ethiopian-air-crash-black-boxe... > but Ethiopian authorities would prefer to work with the U.K.’s Air Accidents Investigation Branch to ensure that U.S. experts won’t have undue influence in the probe of the American-made plane.

https://www.bloomberg.com/news/articles/2019-03-13/ethiopia-... > The choice of Europe over the U.S. National Transportation Safety Board for the analysis of the black boxes is a strategic decision for Ethiopian Airlines and the nation’s government, said Asrat Begashaw, the carrier’s public relations director.

The airline CEO also cited physical distance (and perhaps time zone distance) as a benefit of Europe vs US.

The last loss of aircraft ETA was involved with, 737-800 ET409 in Lebanon, was also sent to BEA.


Given Boeing's behaviour thus far (and the other HN thread about the jackscrew issue they covered up some years back), I can't say I blame them.

With that said, AIAB has just as formidable a reputation as the FAA. If the truth is there, they'll find it.

I would never have held up Ethiopia as the model of incorruptibility. And the NTSB is generally thought to be above reproach. But I guess it's hard to argue that given two competent agencies, the one with the least perceived conflict of interest should do the work.

Ethiopia insisted it go to a third party. They tried Germany first but they didn't have the equipment so they then went to France's BEA[1].

[1] https://gulfnews.com/world/ethiopian-airlines-crash-germany-...

I absolutely agree with not giving the blackbox to the U.S. There is definitely a possibility of a conflict of interest with the F.A.A. not being fully forthcoming. U.S. politicians have a strong interest to keep the U.S. aviation industry strong and Id be surprised if there was absolutely zero interference between politicians and the F.A.A. conducting a fair investigation.

Also, the F.A.A. has already been aware that there were issues with this plane (software fixes were being worked on), but the planes continued to fly. If it turns out that the information already known to them BEFORE the latest crash should have been sufficient to call for a grounding, I could see them attempting to cover their ass.

Can't they just upload all the data somewhere and then any air authority can do as they wish with it?

Who? I want the first person to open the box to get the data be fully trustworthy. That person can upload the data. If the first person to open the box is evil they can substitute whatever data they want.

We are talking about governments here so the conspiracy theory that the person who opened the box substituted a different set of data is actually possible. Conspiracy theory territory for sure, so you really want to make sure that a fully trusted third party is involved. France seems as good as anyone to fit that bill.

Yes, I was thinking the trusted party with authority to open the box could dd whatever storage is in there and share the image(s) publicly.

If you were worried about conspiracies then multiple aviation authorities, or government departments, could send observers to watch the opening and imaging.

Not just that but the Secretary of Transportation is ex Boeing I believe

Acting Secretary of Defense Patrick Shanahan is ex-Boeing and yesterday a government watch dog has asked for an investigation that he violated ethics rules by promoting Boeing weapons systems while serving as a government official.

Secretary of Transportation Elaine Chao was Secretary of Labor under George W. Bush, Distinguished Fellow at The Heritage Foundation, and the wife of Senate majority leader Mitch McConnell.

Can't blame them. US institutions have been slowly poisoned by the cancer call lobbying. You have regulators with interest ties to the industry they have to supposedly regulate all across most agencies.

It isn't just the US, it is everyone in some form. The only people who understand an topic well enough to regulate it are insiders to the industry. The rest of us have opinions that are often misinformed.

Many things might look like smoke to a layperson, but aren't, like contrails or [wingtip vortices](https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hire...).

I don't recall why but I think MH370 recorder was also sent to France. Probably to avoid conflict of interests ?

The MH17 investigation was done by the Dutch mostly- the plane had departed from there.

I think the black box was handled by British investigators:


The debris found in Reunion island was likely handled by France as it is a French overseas department. Debris photos here: https://www.independent.co.uk/travel/news-and-advice/mh370-l...

You mean MH17?? MH370 was never found.

maybe it was the potential piece of fuselage found later then ?

They never found MH370.

They found some purported (maybe confirmed?) wreckage did they not? Seat cushions and other lightweight parts washed up on a beach somewhere? But never the flight recorders.

It's early. The graphs show a dive after takeoff while speed is increasing. That's a loss of control; nobody does that on purpose. More info is needed to know why. Uncommanded nosedown? Actual stall? Something else?

How does the theory of a faulty AoA sensor align with eye witness accounts of smoke coming from the plane?

Also, the altitude data seems to cut out at it's peak. Was the decent so rapid it couldn't be tracked?

> How does the theory of a faulty AoA sensor align with eye witness accounts of smoke coming from the plane?

They don't need to align. Eyewitness accounts are so bad, it's surprising they're allowed in court.

"Why Science Tells Us Not to Rely on Eyewitness Accounts - Eyewitness testimony is fickle and, all too often, shockingly inaccurate"

> Many researchers have created false memories in normal individuals; what is more, many of these subjects are certain that the memories are real.

> In one well-known study, Loftus and her colleague Jacqueline Pickrell gave subjects written accounts of four events, three of which they had actually experienced. The fourth story was fiction; it centered on the subject being lost in a mall or another public place when he or she was between four and six years old. A relative provided realistic details for the false story, such as a description of the mall at which the subject’s parents shopped.

> After reading each story, subjects were asked to write down what else they remembered about the incident or to indicate that they did not remember it at all. Remarkably about one third of the subjects reported partially or fully remembering the false event. In two follow-up interviews, 25 percent still claimed that they remembered the untrue story, a figure consistent with the findings of similar studies.


You example is subjects believing a false story given to them. That's different than someone reporting something that they believed they saw with no prompting from anyone else.

We don't know whether that happened in this case. Maybe journalist (who was there hours later) asked the eye witnesses "did you see smoke or hear strange sounds?" - if so, all bets are off.

Just because the specific story highlights one failing of eyewitness accounts doesn't mean there aren't many, many other ways they are spectacularly inaccurate.

I'm curious what your personal thoughts on TWA 800 are.

''Eyewitness memory is reconstructive,'' said Dr. Honts, who is not associated with the safety board. ''The biggest mistake you can make is to think about a memory like it's a videotape; there's not a permanent record there.''

The problem, he said, is that witnesses instinctively try to match events with their past experiences: ''How many plane crashes have you witnessed in real life? Probably none. But in the movies? A lot. In the movies, there's always smoke and there's always fire.''


See also “Reliability of Eyewitness Reports to a Major Aviation Accident”:


Witness accounts are famously unreliable [1] [2]. They are saying that the flight profile so far matches what they saw with Lion Air 610. Until the FDR and CVR are analyzed the only reliable data is what they have from ADSB and whatever Satcom they have.

[1] https://www.bostonglobe.com/metro/2015/05/23/eyewitness-acco...

[2] https://www.scientificamerican.com/article/do-the-eyes-have-...

Eyewitness accounts are _notoriously_ unreliable. Multiple witnesses saw something approaching TWA-800:

> Although there were considerable discrepancies between different accounts, most witnesses to the accident had seen a "streak of light" that was unanimously described as ascending, moving to a point where a large fireball appeared, with several witnesses reporting that the fireball split in two as it descended toward the water.

> 258 were characterized as "streak of light" witnesses ("an object moving in the sky... variously described [as] a point of light, fireworks, a flare, a shooting star, or something similar.") The NTSB Witness Group concluded that the streak of light reported by witnesses might have been the actual airplane during some stage of its flight before the fireball developed

> In addition, 18 witnesses reported seeing a streak of light that originated at the surface, or the horizon, which did not "appear to be consistent with the airplane's calculated flightpath and other known aspects of the accident sequence."

> [T]he NTSB noted that based on their experience in previous investigations "witness reports are often inconsistent with the known facts or with other witnesses' reports of the same events."


People said they saw a missile hit TWA-800 too. Eyewitness accounts are super unreliable.

A Pilot who hitched a ride in cockpit saved doomed Lion Air Boeing 737 Max day before it crashed. As the Lion Air crew fought to control their diving Boeing 737 Max 8, they got help from an unexpected source: an off-duty pilot who happened to be riding in the cockpit.

That extra pilot, who was seated in the cockpit jumpseat, correctly diagnosed the problem and told the crew how to disable a malfunctioning flight-control system and save the plane, two people familiar with Indonesia’s investigation told Bloomberg.

Why wasn't this information passed on to all Lion Air pilots?

Sound like Air Bus A330 nose dive problem, they had with the software 3 years back, sounds a lot like the Boeing 737 MAX 8 problem that is burning up the news channels. Did AIR BUS ground their A330 world wide fleet when this happened? How did Air Bus handle this?

I've seen many discussions about whether the groundings of the MAX (especially the earliest ones) are hysterical/political or is it based on any facts. The facts is two of these BRAND NEW planes crashed within 5 months under very similar circumstances. Doesn't that alone seems statistically justified to ground the MAX? The chances of human error and/or environmental factor striking twice within such short period seems infinitesimally low, no? Just curious how that math works out.

I don't see anything in this article that wasn't already in the FAA's Emergency Order of Prohibition[1]:

On March 13, 2019, the investigation of the ET302 crash developed new information from the wreckage concerning the aircraft's configuration just after takeoff that, taken together with newly refined data from satellite-based tracking of the aircraft's flight path, indicates some similarities between the ET302 and JT610 accidents that warrant further investigation of the possibility of a shared cause for the two incidents that needs to be better understood and addressed. Accordingly, the Acting Administrator is ordering all Boeing 737 MAX airplanes to be grounded pending further investigation.

This article is further missing the "new information from the wreckage concerning the aircraft's configuration" piece, which is in the NPR interview[2]: And that, coupled with some physical evidence we found at the crash site led us to believe that the similarities were too great not to consider that there was a common thread.

So it wasn't just the flight path, which indeed was sufficient for other countries, but the addition of physical evidence as well:

And when you have a common thread between two accidents, then the argument for grounding becomes necessary. Grounding becomes necessary, and so that's what we did. We didn't have that link until yesterday morning, yesterday afternoon about midday.

GREENE: But isn't this something that analysts and experts have been saying for days now, that these two crashes appeared similar?

ELWELL: Yeah. Many were saying it, but nobody had data to act on it. It was all conjecture. And in aviation, the FAA in the U.S. has always acted on data. We're a data-driven organization. We have the safety record we have today based on science, risk analysis and data.

1. https://www.faa.gov/news/updates/media/Emergency_Order.pdf

2. https://www.npr.org/2019/03/14/703298739/faa-acting-head-dan...

If these two crash had happened in USA or Western Europe . Would the FAA have grounded the 737 right away . Or would they have waited before taking that decision

Turning that around a bit...

If it was a pair of Airbus aircraft (A320, A330, pick any you like) which suffered these two crashes, would the FAA have demanded the whole fleet grounded?

Interesting question as this particular case is suspected to be political/economical involved already.

How strange that they both had issues at around 6000-8500 feet, briefly recovering, then nose diving.

Even more interesting is the recent 767 Amazon cargo flight crash in Texas also did a node dive at around 8000 feet which somehow has escaped the news with this new crash [1]. The pilots decided on a path around weather, were at 11-12000 feet, descended 3000+ feet and then the plane essentially did a similar nose dive. Is this a data problem?

> As the plane passed through 12,000 feet at a ground speed of 290 knots (340 mph), the pilots indicated they preferred the westerly route option ATC had given them around the rain; air traffic control told them they would need to descend quickly to 3,000 feet to do so, and radar data reveals the Boeing turned to a heading of 270º as requested and descended through 8,500 feet. One minute later, the controller told the crew they would be past the bad weather in about 18 miles, and to expect a turn to the north. The crew responded "Sounds good" and "Okay," according to the NTSB, and the plane leveled out at 6,200 feet before rising 100 feet more.

> That, apparently, is when things went haywire. The aircraft began what the NTSB report described as "small vertical accelerations consistent with the airplane entering turbulence," according to the flight data recorders recovered from the accident scene. Seconds later, with the plane holding steading at 230 knots (265 mph), the engines went to full power, and the nose of the plane rose four degrees...then the aircraft pitched nose-down for the next 18 seconds, reaching a maximum pitch of –49º in response to the plane's elevator inputs.

The Ethiopia 737 Max has almost the same issue [2]

> ADS-B data recorded for ET302 by FlightRadar24 shows that the aircraft, after reaching an altitude of 8,025 feet above sea level, suddenly dipped, plunging 400 feet before recovering briefly. But the aircraft's vertical speed remained unstable, and a few minutes later it dove into the ground. For reference, the airport the flight took off from is at 7,631 feet above sea level—so the aircraft never reached more than 500 feet above the ground, not leaving much room for correction.

All of these planes had issues in the 6000-8500 feet range and then both suffered the same plunging fate after briefly recovering from a dip / nose stabilization issue.

Hopefully the ADS system is secure and not susceptible to infiltration/hacks causing the plane to react to incorrect data at a range that is not recoverable.

[1] http://www.thedrive.com/news/26933/amazon-boeing-767-cargo-p...

[2] https://arstechnica.com/information-technology/2019/03/faa-a...

I guess the correlation here is the stalling problem often happens during this height range. Both 737 were in the ascending process, while the 767 is during normal flying.

For me, the 767 hit with some kind of strange turbulence then the engines went to max and caused a typical stall crash. You could google about the stall crash, such as : https://www.dw.com/en/why-do-airplanes-stall-and-why-is-it-s...

For both 737 max, their MCAS system thought they had a stall potential and triggered on nose dive while the airplanes were actually in the perfectly normal situation.

For 767, they do not have this autonomous system and the stall warning was not even triggered. So it was a purely manual operation. If they have a perfectly functioned MCAS like the 737 max has, they may have survived.

So a working MCAS could save plane from crash like 767 had. Just the MCAS on 737 max was not working correctly and MAY potentially have caused the tragedy.

> Both 737 were in the ascending process, while the 767 is during normal flying.

It might not have anything to do with ascent/descent but the range / altitude and how systems react at that altitude. Maybe the systems are designed to be more reactive at this height because there is less chance to recover than if you are cruising at 30k feet.

What is most interesting to me is how the Amazon cargo plane 767 crash made almost zero news and has quickly been replaced in the news with the 737 Max 8/9 issues. Though all situations are very similar, straight nose dives that were sudden at the 6000-8500 feet range. There has to be something to that.

767 crashes and emergencies are EXTREMELY rare [1].

Most are related to human intervention such as terrorism, pilot error, fuel error and only a very small amount are mechanical errors. Of the 12 problems, only 5 were mechanical error.

[1] https://en.wikipedia.org/wiki/Category:Accidents_and_inciden...

That is probably because 767 is a plane with quite a long history without any major upgrade. And it is cargo, so no passengers.

The first 737 Max crashed in Indonesia, it did not have quite media coverage as well. The second one got much more attention because that is quite rare that two brand new flights crashed in such a short period. Everyone suspected it is caused by design or system flaws.

> That is probably because 767 is a plane with quite a long history without any major upgrade. And it is cargo, so no passengers.

767 is a passenger and cargo plane.

I assume you mean the Amazon 767 was a cargo plane [1], in which case yes it got less attention as only the pilots/cargo crew were on board. However, a 767 crashing in the US seems like it would have gotten more focus.

Other 767s are passenger planes including two infamous ones American Airlines Flight 11 (Boeing 767-223ER) and United Airlines Flight 175 (Boeing 767-200) that were the two planes that crashed into the World Trade Center tower 1 & 2 on 9/11 [2][3].

For the most part these planes don't crash and a straight nose dive is a freak occurrence. Most of the other issues that weren't crashes with 767 were landing gear, short fuel related and terrorism.

It is very strange and eerie that this 767 from Amazon crashed almost similarly to the 737 Max 8/9 in Indonesia and Ethiopia recently, with such a long history of nothing like this.

[1] https://en.wikipedia.org/wiki/Atlas_Air_Flight_3591

[2] https://en.wikipedia.org/wiki/American_Airlines_Flight_11

[3] https://en.wikipedia.org/wiki/United_Airlines_Flight_175

> There has to be something to that.

Well, no, there doesn't have to be something to that. Random data often exhibits clusters.

However, it is unwise to assume that there isn't something to that. It just also is unwise to assume that there is. Keep an open mind and investigate.

The only way a plane would need to pitch down -49 degrees is if the plane thinks it is, or is, 40-50 degrees or more pitched up.

The only thing I can think of why that would happen is a software error. Possibly the common occurrence of these planes where the nose is pitching up 4 degrees repeatedly to an almost turbulent state, then possibly the software on the plane thinks it is additively pitched up if there were 10-15 incorrect nose adjustments up of 4 degrees.

Could be a race condition, lock or some other issue where it only happens at that altitude because it has to adjust faster to prevent crashes and the lower you are the harder it is to recover.

My guess is the software acts more decisively at lower altitudes under 9-10k because that is closer to the ground and where some areas of the US have peaks in elevation to, so the aircraft must act quicker because it is less recoverable at that stage.

Another possibility is since it was a cargo plane there was shifting during the turbulent state but the plane was stabilized and moved up 100 feet before the -49 degree nose down state so that seems unlikely.

Pilot error seems unlikely as well as the pilots were skilled.

Mechanical failure seems rare as 767s just do not have nose down errors like this and almost no mechanical causes of emergencies or crashes.

There is always the possibility of sabotage as well, there are reasons groups might want to take down an Amazon owned plane.

Though most likely this is a software error or something exploited.

I'm not certain that particular 767 has a stick shaker but I'd be surprised if it didn't. My concern with any cargo airplane crash is weight and balance, was center of gravity in the normal envelope, and did anything shift during turbulence? That shouldn't happen, but if it does, it can really adversely affect stall avoidance and recovery. From the look of the grainy surveillance video of that crash, it could be stall crash, it does vaguely look like they might have been recovering but flat out had insufficient altitude.

Also with respect to MCAS, it's not a factor when the autopilot is enabled, as the autopilot shouldn't permit approaching the edges of the normal envelope with such a high angle of attack that the MCAS routine would apply. I haven't read any report about whether the autopilot was enabled or not; let alone the exact sequence of modes enabled and disabled. So the autopilot itself can't be excluded as a suspect until there's evidence it was a non-factor.

The Amazon leased 767 that crashed was a full on cargo version. Cargo is stored in large containers. And the aircraft filled with them. Things shifting in those tend to only shift inside the container. Unless Amazon was shipping lead bricks I don't think any cargo escaped the containers.

But the 767 was descending. It was SUPPOSED to be going down.

What I recall reading is that the nose was already down somewhat before changing pitch 4 degrees THEN pitching sharply down in direct response to pilot input.

ADS-B data is being TRANSMITTED. The plane is not responding to ADS.

Whatever the case the planes all had similar issues with momentary nose elevating issues, then a direct nose dive. The 767 was just taking an alternate course around weather. I find it hard to believe the 767 pilot who was very skilled decided to nose dive on their own at -49 degrees pitch. Something with the system was off for it to do that.

The feet measurement was above sea-level not ground-level. The airport there is around 7600 feet. So in actual fact this plane was only sitting 500-1000 feet above ground.

There was no confusion on that. The elevation/altitude the planes were at was near the same ranges 6000-8500 feet above sea level, flight level varied, flight level is to the ground, elevation/altitude is to sea level.

Possibly the software is more reactive when it is in ranges where it may be close to the ground or the highest elevation. Highest elevations in the US are around that range and a range where it is harder to recover so it may be more reactive. At 30k feet elevation/altitude (from sea level) or flight level (from ground) the software might not have to take as evasive moves.

I don't know what you mean by flight level. Flight level is a standard term in aviation and is based on pressure altitude. Strictly speaking pressure altitude is the height above the standard datum plane at standard temperature and pressure, but for practical purposes it's above mean sea level.



Pilot vernacular often uses just `altitude` but which kind of altitude depends on context, but if there's ambiguity I say MSL (mean sea level) or AGL (above ground).

By flight level I meant from above ground level (AGL).

The previous commenter was thinking we were talking about height relative to ground level.

Altitude/elevation is height from sea level as specified.

I used flight level more as above ground level (AGL) but it also means not all the way to sea level and takes into account ground terrain.

The point being that all these planes (both 737s and the 767 Amazon cargo plane) all had similar issues between 6000-8500 feet in altitude (from seal level) but the ones that crashed on ascent took off from higher ground.

Moot point as it was sea level/altitude where all these plans had the same repeating/turbulent nose up 4 degree turbulence, then a direct 49 degree nose down state that led to the crashes, regardless of AGL.

Whether related or not the planes all experienced a nose dive in that range that was catastrophic.

It makes more sense with the 737 Max planes as they have center of gravity further back and software has to keep the nose down/straight, it makes zero sense for the 767 do similar movements unless it is common across software in that altitude range for some reason, possibly being more reactive at that range because of common elevations and it is harder to recover at that point.

I was going to suggest this is likely a common cruizing height, but no, it doesn't seem to be. That's an interesting correlation.

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