
Similarities Between the Lion Air and Ethiopian 737 Max Crashes - jaredwiener
https://thepointsguy.com/news/similarities-lion-air-ethiopian-737-max-crashes
======
tuna-piano
Sympathies for all the victims and their families, incredibly sad.

Many of us have heard the phrase "If it ain't Boeing, I ain't going." In
reference to Boeing's perceived safe planes. This phrase has lost any meaning
to me, and in fact, I'm feeling the opposite way right now.

Boeing's response to the first 737-Max Lion Air crash was abhorrent, in my
opinion. While they were taking the time to blame the Lion Air pilots reaction
to the plane's issue, and stating how safe the 737-max was, they were also
working on urgent patches to their software. The patch is still not yet
deployed, but the planes continue to fly.

If initial info of this crash points to a related cause to the Lion Air crash,
anything less than a full grounding of all 737-Max aircraft seems incredibly
dangerous. I get the feeling that Boeing executives have checked their better
moral judgement at the door and are thinking solely in terms of dollars.

I can't help but feel that Boeing and US regulators would have taken the issue
identified after Lion Air much more seriously and been much more likely to
take action and responsibility if it was a US flight. That thought leaves me
with incredibly sour taste in my stomach.

For those who may come to Boeing's defense, take a look at how pilots of the
737 Max responded to the Lion air crash - often with anger.

[1] [https://www.nytimes.com/2019/02/03/world/asia/lion-air-
plane...](https://www.nytimes.com/2019/02/03/world/asia/lion-air-plane-crash-
pilots.html)

[2] [https://www.washingtonpost.com/business/2018/11/13/pilots-
un...](https://www.washingtonpost.com/business/2018/11/13/pilots-unions-
criticize-boeing-withholding-safety-information/?utm_term=.6da8413fb849)

[3] [https://www.fullwsj.com/articles/regulators-push-for-
clarity...](https://www.fullwsj.com/articles/regulators-push-for-clarity-on-
boeing-737-safety-systems-after-lion-air-crash-1542854965)

[4] [https://www.fullwsj.com/articles/boeing-and-regulators-
delay...](https://www.fullwsj.com/articles/boeing-and-regulators-delay-
jetliner-fixes-prompted-by-lion-air-crash-11549821489)

~~~
panarky
We can't afford to wait for evidence proving beyond a reasonable doubt that
this aircraft is dangerous.

Probable cause should be a sufficient standard.

Two crashes in similar circumstances is probable cause to take them all out of
service until they figure out what the hell is going on.

For myself and my family, we won't wait for regulators and airlines to act. We
will not fly the 737 Max.

~~~
twtw
It's interesting that you reach that conclusion.

I'll fly 737 max.

I won't fly Lion Air or Ethiopian Airlines.

Southwest: fleet size 754, founded 1967, total of seven accidents with 3
deaths.

Ethiopian Airlines: fleet size 107, 64 accidents with 459 deaths since 1965.

~~~
panarky
I don't have data on flight miles or flight segments by type of aircraft, so
let's do a quick and dirty estimate.

Let's say there are 40,000 commercial aircraft worldwide and 350 of these are
the Boeing 737 Max [0].

If all aircraft are equally likely to crash, then the probability of a given
crash being a 737 Max is 350/40000 = 0.00875.

The probability that two crashes are both 737 Max is 0.00875 * 0.00875 =
0.0000766

It's extremely unlikely that an aircraft representing less than 1% of the
global fleet would crash twice in a short period of time unless there is a
serious defect with that aircraft.

That's well past probable cause at this point. This aircraft should be
grounded until they figure this out.

[0]
[https://en.wikipedia.org/wiki/List_of_Boeing_737_MAX_orders_...](https://en.wikipedia.org/wiki/List_of_Boeing_737_MAX_orders_and_deliveries)

~~~
Steko
> The probability that two crashes are both 737 Max is 0.00875 * 0.00875 =
> 0.0000766

You need to multiply this by every combination of two crashes in the observed
time period with starting and endpoints not cherry picked to include 737 max
crashes though.

~~~
panarky
Be my guest. You'll find that the probability of a rare aircraft crashing
twice in a short period of time is infinitesimal, unless that aircraft
contributed to the catastrophe.

~~~
Steko
It's hardly infinitesmal, that's my point.

With an average of 175 737's operating since launch, 4K total widebody
commercial aircraft and over a dozen widebody crashes in that period, you get
over 10%. Some estimates there but you still have the endpoint issue as well.

~~~
panarky
There have been a total of 5 commercial air disasters in 2018 and 2019 with
fatalities that didn't involve hijacking, landing short of the runway or
overshooting the runway [0].

And that includes the crash of a cargo flight with no passengers where the
crew was killed.

The 737 Max 8 was involved in 2 of those 5 disasters.

There are between 25,000 and 39,000 commercial aircraft in service depending
on who you ask [1].

With 350 737 Maxes delivered so far, that's at most 1.4% of the total today,
probably less than half that this time last year. Let's call it 1% on average
for 2018 and 2019 combined.

There are 10 ways you can have 2 Max crashes out of 5 total crashes. So the
probability is 10 * 0.01^2 * 0.99^2 = 0.00098

Even accounting for n choose k and longer endpoints, it's still an
infinitesimal probability that we'd see two catastrophes with the same rare
aircraft -- unless that aircraft contributed to the catastrophe.

It should be grounded.

[0]
[https://en.wikipedia.org/wiki/List_of_accidents_and_incident...](https://en.wikipedia.org/wiki/List_of_accidents_and_incidents_involving_commercial_aircraft#2018)

[1] [https://www.telegraph.co.uk/travel/travel-truths/how-many-
pl...](https://www.telegraph.co.uk/travel/travel-truths/how-many-planes-are-
there-in-the-world/)

------
Reason077
AFP is reporting that an eyewitness saw the aircraft on fire before the crash.
If confirmed, that makes this quite difference circumstances to the Lion Air
crash.

> _An eyewitness told AFP the plane came down in flames. “The plane was
> already on fire when it crashed to the ground. The crash caused a big
> explosion,” Tegegn Dechasa recounted at the site. “I was near the river near
> the crash site. Shortly after the crash police and a fire crew from a nearby
> air force camp came and extinguished the plane’s flames on the ground.”

> He added: “The plane was in flames in its rear side shortly before the
> crash. The plane was swerving erratically before the crash.”_

Source: [https://www.theguardian.com/world/2019/mar/10/ethiopian-
airl...](https://www.theguardian.com/world/2019/mar/10/ethiopian-airlines-
says-kenya-flight-with-157-onboard-has-crashed)

~~~
in_cahoots
With all respect to the witnesses, early eyewitness reports are notoriously
unreliable. I remember reading the exact same thing about the plane that
crashed in NYC shortly after 9/11\. There were also many ‘eyewitnesses’
claiming to see the crash of the Malaysian airliner. This report may wind up
to be substantiated, but I wouldn’t put any weight on it until then.

~~~
cm2187
Also TWA 800, where many eyewitnesses saw a missile that was never there.

~~~
ru999gol
not sure if citing that as an example is such a good idea, considering
everything surrounding it. You do have to reject an awful lot of evidence to
claim with certainty there was never a missile.

~~~
ourmandave
They spent 4 years and $40M on the investigation which including recovering
most of the fuselage from the Atlantic and reassembling it in a warehouse.

------
rpmcmurphy
Pilot here. I predict that airlines are going to soft ground the Max while
this gets sorted out. They might not take them out of service completely, but
would not surprise me a bit if they rely on other equipment where possible
until this gets sorted out. Better to take a hit on increased fuel costs that
risk the loss of an aircraft and all on board.

~~~
51Cards
Would you mind detailing the term "soft ground" for my own knowledge? Thanks

~~~
AnimalMuppet
I think rpmcmurphy's middle sentence explained it: If you can, fly something
else. If you're out of all flavors of "something else", then fly the 737 Max.

------
pmm
There were 41k flights until May 2018 [1]. I was not able to find the current
number but with 350 models delivered so far and 4 average flights per day that
would sum up to ~500k flights in total at most (but more probably half of that
due to ramping up the deliveries).

With 2 accidents the rate is now 4/million. That's at least an order of
magnitude difference more than the average of the modern jetliners [2]

Of course, with two events it might be just bad luck but the similarities are
concerning, as pretty much everyone observes here

[1] [https://randy.newairplane.com/2018/05/22/737-max-a-year-
of-s...](https://randy.newairplane.com/2018/05/22/737-max-a-year-of-serving-
the-globe/) [2]
[http://www.airsafe.com/events/models/rate_mod.htm](http://www.airsafe.com/events/models/rate_mod.htm)

------
whoisjuan
I'm not paranoid, but if I can avoid flights operated with the 737 MAX, I
will. Two accidents in 5 months is a dangerously high fatality rate for a new
jet.

~~~
MuffinFlavored
I'd be curious to hear how many successful flights have happened since the 737
Max has launched, for comparison.

~~~
rootusrootus
IIRC someone on airliners.net (not an authoritative source, but enthusiasts)
said it was something like 150K. That sounds plausible, given they have
produced about 350 of them and the first one flew (commercially) in 2017.

------
cedivad
This guy on reddit claims to be a software engineer at Boeing and talks about
how the system was mostly worked on by people that didn't understood how it
worked, as the core was fortan and they were writing their patches on top of
it in other languages.

[https://www.reddit.com/r/aviation/comments/azds6k/ethiopian_...](https://www.reddit.com/r/aviation/comments/azds6k/ethiopian_airlines_737_plane_crashes_en_route_to/ei7k7m0)

------
acqq
Relevant (about the first crash):

[https://www.21stcentech.com/bad-software-boeing-737-max-
comm...](https://www.21stcentech.com/bad-software-boeing-737-max-commercial-
jet/)

"Those 189 who died were victims of Boeing’s redesign of its successful 737
aircraft, all about _putting a bigger engine on it and trying to come up with
a solution to correct the airplane’s changed aerodynamics_. Boeing realized
the redesign could lead to potential stalls. MCAS was the answer"

" _Software combined with sensors would ensure the airplane would not tilt
upward at an unsafe rate_. The combination of the two would keep the nose at
the precise right angle during all aspects of flight to prevent a potential
stall.

Was this, in the end, a good design decision? No based on what occurred to
this nearly brand new aircraft"

"Pilots can manually override the MCAS but cannot switch it off without
switching off the flight computer. This fact in and of itself proved fatal to
Flight 610, its crew, and passengers."

"Since the crash Boeing has sent out _a safety warning with a procedure for
cutting off MCAS in the event of an AOA sensor malfunction_. A description of
what a pilot would experience should the MCAS receive false data has been
included so that he or she would know when to disengage the flight computer
and manually take over flying the plane."

Moreover, bad software effectively working against the pilots, again connected
to the stalls, was also the cause of this famous accident some 10 years ago:

[https://en.wikipedia.org/wiki/Air_France_Flight_447](https://en.wikipedia.org/wiki/Air_France_Flight_447)

"In an article in Vanity Fair, William Langewiesche noted that once the angle
of attack was so extreme, the system rejected the data as invalid and
temporarily stopped the stall warnings. However, "this led to a perverse
reversal that lasted nearly to the impact: each time Bonin happened to lower
the nose, rendering the angle of attack marginally less severe, the stall
warning sounded again—a negative reinforcement that may have locked him into
his pattern of pitching up", which increased the angle of attack and thus
prevented the aircraft from getting out of its stall.[25]"

~~~
youngtaff
This is so important… most airlines are inherently stable by design but the
737 Max requires software to be stable

~~~
twtw
No, it doesn't. The 737 max has software to prevent stalls in situations
outside of the profile of normal flight. As does e.g. the A320.

~~~
dmix
Yep Apparently the main problem seems to be the fact there is a single point
of failure (a single AoA sensor) and it could be resolved by having multiple
sensors. Not that some sort of new automation is occurring than before.

~~~
ggreer
The 737 max has multiple AoA sensors.

Having multiple sensors doesn't always help, as failures are correlated. For
example, there was an Airbus A321 that had 2 of its 3 sensors get stuck in the
same position due to icing.[1] The computer thought that the one working
sensor was malfunctioning and disregarded it. It then engaged stall
protection, dipping the nose and causing the plane to dive at 4,000ft per
minute.

> The captain continued to hold “more than 50%” rearward stick in stable
> flight for a period, but with help from technicians on the ground, the crew
> was able to reconfigure the automation into the aircraft’s alternate control
> law, rather than its normal “direct” law. The action removed the alpha-
> protection checks and canceled the nose-down input. The aircraft then
> continued to its destination.

These failure modes tend to happen more with Airbus planes because their
flight control systems default to overriding human input if the computer deems
it unsafe. Boeing's flight computers will give more resistance in the
controls, but they mostly won't prevent the pilot from doing what they want to
do. The exceptions (such as auto-trim and stall prevention) can be disabled
with by flipping a couple of switches.

1\. [https://aviationweek.com/commercial-aviation/german-
investig...](https://aviationweek.com/commercial-aviation/german-
investigators-cast-wider-net-frozen-aoa-sensors-pamplona-dive-incident)

~~~
dmix
True but 2/3 failing instead of 1/1 is still the better option. I’ve read the
Max only used one sensor for the MCAS system.

But I’m not an expert on the subject so I’ll defer to the reports and more
knowedgable people.

------
DevX101
They should ground all 737 Max (350 have been built so far) until
investigators understand fully what caused these two crashes and a fix is
implemented (if it is proven that there was fault in the plane itself).

It's highly unusual for a plane that has been in operation for only 3 years to
have two crashes shortly after takeoff.

I certainly won't be taking any flights in them until a thorough explanation
emerges of what happened on these two flights.

And Boeing PR should stop saying that the planes are safe (they recently put
out a statement affirming it's safety). At best, they should say "we don't yet
know, and are investigating".

~~~
liability
I understand and agree with the suggestion that the whole fleet be grounded,
but isn't personally avoiding the planes an overreaction? While the chance of
another fatal crash in the imminent future may be high, surely the chance that
_you_ would be on it is still quite low.

~~~
MuffinFlavored
Going on a 737 MAX plane: X% chance of dying

Going on a non-737 MAX plane: Y% chance of dying

Given these two accidents, X > Y

Why sign up for a higher chance of dying?

~~~
liability
If both are very small, then why wouldn't some other factor like minor
convenience wash out the minor safety concern? I don't know about you, but I
pick my flights by airline, time, and price. I wouldn't degrade any of those
for a very small increase in safety.

~~~
pmm
Right now the MAX version is at least an order of magnitude less safe than the
previous generation (put some rough estimated in another comment)

~~~
liability
Airliners are exceptionally safe as a general rule. Small GA planes are _TWO_
orders of magnitude less safe. Would you avoid a flight in a single engine
prop plane? I wouldn't. While it's a _certainty_ that many people will die in
small plane crashes this year, it's still unlikely that the particular plane
I'm on will crash.

I think this is a classic case of people overreacting to dramatic but unlikely
risk. And to be clear, I support grounding the fleet.

------
everyone
Being aware of the general standard of software devs + teams, it is terrifying
to think that my life is in their hands.

Thats not the case with structural or civic engineering say. The more I know
about that the safer I feel.

~~~
sn41
There's also the misplaced emphasis on speed. Software safety and verification
courses are considered "advanced" level. CS undergraduates are now led to
believe that logic is a bore, and is old-fashioned computer science. Of
course, with the advent of machine learning, "It Works!" is now considered as
enough proof, so that's a whole new level of crazy.

~~~
AnimalMuppet
Permit me to point out that "It works!" is _not_ considered enough proof for
flight software.

------
sfilargi
There is am interesting discussion here:

[https://www.airlinepilotforums.com/safety/120514-ethiopian-7...](https://www.airlinepilotforums.com/safety/120514-ethiopian-737-crash-2.html)

------
breatheoften
How long does it take to ground an aircraft assuming the decision to ground is
made?

~~~
sokoloff
For an airliner, decision could be implemented in under 24 hours if a
country’s civil aviation authority (FAA for the US) decides it’s an emergency.
More likely, they’d permit ferrying to maintenance bases, and very unlikely to
emergency ground the aircraft absent a finding of same root cause, even if
preliminary. I’d be surprised if they took a fleet wide emergency grounding
action.

~~~
xucheng
Is there any recent history for FAA to issue an emergency grounding for one
type of aircraft?

The only example I know is DC-10.

~~~
cm2187
Perhaps Concorde, although I don't know if the emergency grounding was
mandated by the authority or voluntary.

~~~
CaptainZapp
As I recall one of the problems with the Concorde was that the existing fleet
was getting quite old and spare parts were hard, if not impossible to come by.

The incident in Paris may have sped up the process of decomissioning the
plane, but it would have happened anyway eventually.

All was not lost. A lot of the more visionary aspects of that plane, were
implented into later Airbus models (i.e. the glass cockpit derives directly
from the Concorde).

An outstanding (if slightly outdated) discussion about all things Concorde can
be found here: [https://www.pprune.org/tech-log/423988-concorde-
question.htm...](https://www.pprune.org/tech-log/423988-concorde-
question.html)

------
_cs2017_
IIUC, preliminary investigation said Lion Air plane wasn't airworthy before
its flight and basically blamed Lion Air for poor safety processes:
[https://wkow.com/news/top-stories/2018/11/28/lion-air-
crash-...](https://wkow.com/news/top-stories/2018/11/28/lion-air-crash-
officials-release-findings-of-preliminary-investigation/),
[https://www.indonesia-investments.com/news/todays-
headlines/...](https://www.indonesia-investments.com/news/todays-
headlines/preliminary-findings-fatal-lion-air-crash-reported-by-
investigators/item9042)

OTOH, I've also seen independent analysis that suggests Boeing was to blame
due to the poor disclosure of important changes in the system.

What can explain such a difference in the primary messages from investigators
and from analysts?

~~~
gamblor956
Boeing failed to disclose important changes in the system. _And_ Lion Air's
maintenance rendered the plane unsuitable for flight. They can both be
contributing factors to the earlier crash.

If the EA flight was caused by the same sensor problem as the LA flight, then
it would appear that Boeing's changes were the primary (and superseding) cause
of the earlier crash, rendering Lion Air's non-maintenance moot from a legal
point of view (in the US, for purposes of assigning damages).

~~~
_cs2017_
Oh so it could imply that Boeing is responsible for two independent
contributing factors: sensor malfunction and failure to disclose system
changes, correct?

Wouldn't Lion Air processes still remain relevant as a third contributing
factor, since fixing any of these factors could have reduced the probability
of the accident?

~~~
rootusrootus
Sensors fail, at some point that becomes the airline's responsibility to
maintain and not something which can be blamed on the manufacturer. Lion Air
had reason to believe the sensors were malfunctioning and they still flew the
plane unfixed.

------
gok
Wonder if many airlines just made a habit of flying with broken AoA sensors,
which until the 737 MAX was easy to get away with.

~~~
781
That would still fall on Boeing, it would be their responsibility to make it
clear that what was acceptable in the past (broken AoA sensor) is not anymore.

~~~
mjevans
I doubt any company would have supported that configuration officially in the
past. That it happened to work is another matter entirely.

One of the engineering improvements that (as an armchair viewer) believe needs
to be made is better communication of auto-pilot state to the crew. ANY
deviation from designated human input needs to be clearly communicated to the
pilots so they know what the hell is doing it and if necessary which system(s)
to disable to regain full manual control.

------
woodandsteel
I have read that the reason pilots were not informed of the software and
procedure changes is that part of Boeings sales pitch for the 737 Max was that
it would require minimal re-training of pilots who had already been flying
earlier 737's.

~~~
dmix
Not quite. Boeing said they didn’t want to deluge pilots with information when
training them on the new plane and that existing manual procedures cover how
to deal with the problem by disabling a system. Aka they didn’t see changing
training or the manual as an immediate solution.

But the final report of the first crash isn’t even out yet. Which I find
interesting considering all the finger pointing going around (even by arm
chair “concerned citizens” in this thread).

Assuming we even know what happened I doubt the solution will end up being a
training thing and most likely updates to the software, UX, and/or the
addition of back up AoA sensors.

~~~
FartyMcFarter
> But the final report of the first crash isn’t even out yet. Which I find
> interesting considering all the finger pointing going around (even by arm
> chair “concerned citizens” in this thread).

If a supposedly-very-safe type of hardware kills a bunch of people _twice_ in
similar-looking incidents, that is very worrying.

It's a rational reaction to look at these incidents and go "yeaah, I'm going
to try and avoid those planes" regardless of whether official reports are out
or not.

------
aclissold
It’s interesting to observe that, _if_ this is indeed caused by a failure in
the stall prevention system (and I say “if” since it’s certainly too soon to
draw conclusions), the media and discussion around it seems to gravitate
towards disabling the system or avoiding the aircraft entirely.

But when we think forward to the inevitable autonomous vehicle accidents that
will occur, the conversation turns to how many lives they’ll have saved, and
how much safer they’ll be.

Is there a known psychological phenomenon for “negative hindsight, positive
foresight” that I can go learn more about?

~~~
jimktrains2
> But when we think forward to the inevitable autonomous vehicle accidents
> that will occur, the conversation turns to how many lives they’ll have
> saved, and how much safer they’ll be.

Driving to the airport is orders of magnitude less safe than flying. If a
malfunctioning automatic system is decreasing the reliability of flying,
that's a huge problem. However, I'd wager that even an autonomous car that's
only just able to pass a driver's exam would be significantly safer than a
human driver because it would _follow the rules_ and _not be distracted_. Even
if that system isn't perfect, it's probably still better than an experienced
driver.

~~~
dwighttk
Except we test humans with tests designed to show that a human who is capable
of generalizing knowledge can do a few things that prove they can do more
things than that. If the AI isn’t capable of that then just being able to pass
the drivers test might create a very incapable AI

------
narrator
In a way similar to how the third leading cause of death is medical errors, in
the future, one of the leading cause of death will be computer bugs.

------
breatheoften
How long does it take for the plane to crash plane after an over-thrust
induced stall condition? How long does it take to crash the plane after an
errant MCAS induced nose-down event (which might not be overridden by pilot
response)?

------
samfisher83
If it ends up being due to faulty sensors they need to add a big disable all
assistive software systems switch. It needs to be easy to access switch not
something you have to go through 5 menus.

~~~
twtw
There already is a switch to disable auto trim. The pilots on the flight prior
to 610 used it, as trained. The pilots on 610 did not.

------
jtms
Many comments are debating where blame for the incident lies - some suggesting
that Boeing is simply pushing blame onto the carrier and not admitting fault.
This very well could be the case, but I do wonder why the crashes of this
plane (to my knowledge) have all occurred with carriers that have less than
stellar safety records. If this crash had been a European, American, or other
airline with a top safety record I would have significantly greater suspicion
of the plane model and Boeing specific problem and not just poor safety
procedures and training with the airline.

~~~
shaki-dora
Going from “Ethiopia” in the airline’s name to an assumption (against factsv)
of a bad safety record is textbook racism.

~~~
jtms
I think going from an entire continent that has a seriously bad safety record
and would be EASY to assume (if you didn't know better, which I didn't) that a
member country of said continent probably also has safety and process issues
to "you're a racist" is a pretty big overreach. People are WAY too cavalier
with that branding of people's intentions. You in no way know me, where im
from, who I am... and yet you call me that? Tsk tsk... shame on you.

------
PaulHoule
It is a little off topic, but I hate flying the 737. The way it is shaped
makes it feel tiny on the inside even when compared to the much smaller
Embrarer E175. It seems to be the only large airliner you will find on
domestic flights in the U.S. and it makes me take the bus or drive if I had a
choice.

If Boeing were to give the 737 the 787 treatment the benefit to the flying
public, airlines, environment, etc. will be huge but as long as Boeing can
sell the 737 without a real upgrade it is a cash cow for them and they'll
never stop making it.

~~~
ryguytilidie
"If Boeing were to give the 737 the 787 treatment the benefit to the flying
public, airlines, environment, etc. will be huge but as long as Boeing can
sell the 737 without a real upgrade it is a cash cow for them and they'll
never stop making it.'

The MAX 8 is very literally the 737 being given the 787 treatment. What are
you asking for here? 10 abreast seating? Then it would just be a 787...

~~~
verelo
Yeah the 787 is a very different plane, and imo a lovely flying experience as
a passenger. Less noise, lower cabin altitude, spacious cabin, modern
passenger cabin tech...it's great! I hope it's safe, but frankly after whats
happened recently, I have my doubts.

~~~
dehrmann
There's a fear that a carbon fiber body won't perform as well in an Asiana
Airlines Flight 214-type crash because it's apt to shatter rather than just
deform like aluminum.

~~~
verelo
Yeah reasonable, but i wonder if it’s also less likely to have stress
fractures that could result in unpredictable failure?

[https://en.m.wikipedia.org/wiki/Aloha_Airlines_Flight_243](https://en.m.wikipedia.org/wiki/Aloha_Airlines_Flight_243)

~~~
dehrmann
In theory, but aircraft are rated for and maximum number of takeoff and
landing cycles so that stress fractures aren't a problem while they're in
service.

Carbon fiber could change some of the economics around that, but I'm not sure
if the airframes wear out from stress before or after efficiency gains make
new planes more desirable.

------
Someone
_”Both Aircraft Were Boeing 737 MAX 8 Aircraft”_

I don’t see why that warrants mentioning, in the context of the article, where
both planes are 737 MAX. Given that _”More than 320 of the 350 Boeing MAX
aircraft delivered through January 31, 2019, are of the MAX 8 variety”_ , it
would be more surprising if they weren’t both a MAX 8 (probability of the
latter is about 1:6, if we assume all variants are equally safe)

~~~
hereiskkb
Incident relationship. Two incidents for the same aircraft type in 5 months is
a unicorn in the wild situation for aviation. Except like an evil unicorn.
That's why it warrants mention.

~~~
Someone
But, having established that both were 737 MAX ( _”However, Sunday’s crash of
an Ethiopian Airlines 737 MAX is the second fatal incident involving the
aircraft type in just five months”_ ) the observation that both were 737 MAX 8
is not surprising at all, given that >90% of 737 MAX’s in service are of that
type.

~~~
peferron
They should also not have mentioned that both planes were Boeings, since 100%
of 737 MAX are Boeings.

