June 4, 2025 • 50 mins
On May 25, 1979, American Airlines Flight 191 lifted off from Chicago's O'Hare Airport only to have its left engine tear completely free from the wing seconds later. In just 31 terrifying seconds, the crippled McDonnell Douglas DC-10 rolled onto its side and plunged to earth, killing all 271 people onboard and 2 more on the ground. Discover how an airline's time-saving maintenance shortcut led to a catastrophic structural failure that changed aviation maintenance practices forever. This harrowing examination of America's deadliest air disaster reveals how a complex chain of design vulnerabilities, maintenance errors, and regulatory oversights culminated in tragedy and permanently altered the public's perception of what was once considered one of the most advanced passenger jets in the world.
Sources:
- "What Caused The Crash Of American Airlines Flight 191?" - Simple Flying, by Jake Hardiman & Luke Bodell, updated February 8, 2024
- "Aircraft Accident Report: American Airlines, Inc., DC-10-10, N110AA, Chicago-O'Hare International Airport, Chicago, Illinois, May 25, 1979" - National Transportation Safety Board, Report Number AAR-79-17
- "American Airlines Flight 191" - Wikipedia article documenting the accident, investigation findings, and aftermath
- "Seconds From Disaster: Chicago Plane Crash" - National Geographic documentary, Season 1, Episode 5
- "Air Disaster: Catastrophe at O'Hare" - Smithsonian Channel documentary examining the crash and investigation
- "Breaking Point" - MSNBC Why Planes Crash series, Season 1, Episode 2
- "Fatal Force: The Crash of American Airlines Flight 191" - FAA Lessons Learned document analyzing maintenance failures
Find FINAL BOARDING CALL online:
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Credits:
Final Boarding Call is hosted by Alice Stern and Zach Stemas, researched and written by Alice Stern, produced and edited by Alice Stern and Zach Stemas.
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
(00:00):
Picture this.
A beautiful spring afternoonat Chicago's O'Hare Airport.
A fully loaded American Airlines DC 10thunders down the runway beginning what
should be a routine flight to Los Angeles.
As the massive jet liner liftsoff, something unthinkable happens.
(00:20):
The left engine rips away fromthe wing flipping up and over.
Before crashing back down onto the runway.
The stricken aircraft continuesto climb, trailing a mist
of leaking hydraulic fluid.
And fuel.
We're about to experience whathappens when a mechanical failure
(00:41):
caused by a maintenance shortagetriggers the deadliest air
disaster in American history.
So stow your tray tables, fastenyour seat belts, and prepare for
some extreme turbulence becausethis is final boarding call.
(01:03):
Hello and welcome to Final Boarding Call.
I am your disaster obsessed host Alice.
And I am Zach, who's not near as reluctantthese days, but today a little tired.
Zach, a reminder for thepeople before we dive in.
Please like, rate, review andsubscribe wherever you get your
(01:24):
podcasts, you're getting reallygood at your one queued line.
That's like the rest of the showfor Zach is completely unscripted.
But that's like, you know, you gottathrow the dog a bone every once in
a while except I don't get a script.
It'd be easier if I did.
You have an insane memory.
You absolutely do not need one period.
(01:44):
Maybe I won't.
One.
And that's a fact . let's talksources before we dive in.
A so the sources for thisepisode there are a handful.
So there is a,
I don't know what you're doing withyour hand, but you're making me nervous.
I'm waiting to count.
You said a handful.
Oh my God.
Oh my God.
(02:05):
Zach just literally put a fistin the air and I was like,
is this the, is this the day?
Is it going down for realright now on the podcast?
While recording was the first timeI struck someone that's struck
my wife, I was to struck a woman.
Definitely struck peoplefor, okay um, sources.
(02:25):
What caused the crash of AmericanAirlines Flight 1 91 by simple flying.
and the article was written byJake Hardiman and Luke Bode.
Obviously Wikipedia has aton of information on this.
There is a Nat Geo documentary actuallyon this as well, called Seconds
From Disaster Chicago Plane Crash.
(02:48):
There is a Smithsonian Channeldocumentary on this crash as well.
M-S-N-B-C-Y planes Crash.
Season one, episode two.
I know I've got a lot for this one,but it's because it is the deadliest
aviation disaster in the United States.
So that's big.
Here we go.
To understand the disaster ofAmerican Airlines Flight 1 91.
(03:11):
We first need to understand theaircraft, the McDonald Douglas, DC 10.
So Zach, we are in the 1970s.
We're back.
It seemed to be a decade of alot of plane shit going down.
The DC 10 represented the cuttingedge of aviation technology.
(03:37):
This bad girl was a wide body, three jet,three engine jet liner that was designed
to compete with the Boeing 7 47, whichwe are extremely familiar with, right?
The Boeing 7 47, an economyclass is a 10 seater aircraft.
It has the little upper deck thing thatwe've talked about where like there
can be cool stuff up there or nothing.
(04:00):
I've never been up there so.
We're gonna pretend it's nothing'cause we don't get to go there.
I know in my head it's like an aquarium.
It's definitely not that Iknow, but in my head it's, so
the DC 10 might sound familiar to ourlisteners because we did talk about a
DC 10 in our Japan Airlines Flight 9 07 and 9 5 8 episode, which involved a
(04:24):
Boeing 7 47 and a McDonald Douglas, DC 10.
And interestingly enough, thatincident specifically takes
place in January of 2001.
So how crazy is it that the episodewe're covering today is in the seventies?
And we covered another DC 10episode that took place in 2001.
(04:48):
Okay.
Anyway, so with its distinctive threeengine configuration, one under each
wing, and one mounted in the tail, theDC 10 could carry up to 380 passengers
and fly intercontinental routes.
So very similar to the 7 47.
(05:10):
The specific DC 10assigned to flight 1 91.
That day was registrationnumber N 11 zero aa.
It had been delivered to AmericanAirlines in February of 1972,
and it had logged just under20,000 hours of flying time over.
(05:30):
Its seven year service life.
So it's not old.
It's not new, but it isn't likearchaic, you know, I don't think
seven years for and for a plane.
Is that crazy?
20,000 miles.
(05:50):
I mean, I don't know.
20,000 hours or, yeah, sorry.
20,000 hours.
Pilots let us know it was poweredby three General Electric CF six
engines, so that's actually interesting.
I didn't know that General Electric made.
Plane engines.
Did you know that when I thinkof ge I think of a washing
(06:11):
machine or a refrigerator.
My mind does not go to plane engine.
Well, you have to picture once upona time, anybody that was making all
of these I guess technology basedinstruments of sorts, Yamaha made
motorcycles and musical instrumentsand engines and all kinds of stuff.
(06:32):
That's fair.
That's fair.
So each of these engines was capable ofproducing over 40,000 pounds of thrust.
So that's like having the powerof around 800 family cars in
each engine, and it had three.
What kind of family carare we talking about?
Don?
(06:52):
Are we talking about don't theseventies where they had a small
block Chevy, small block Chevy
but the DC 10 had alreadyexperienced some troubling incidents.
In 1972, a cargo door blew outon American Airlines flight 96.
And we are going to cover thatstory, so I'm not going to dive
into it too much, but know thatthat happened and it was bad.
(07:15):
Then in 1974, a nearly identicalproblem caused Turkish Airlines flight
9 8 1 to have an incident as well.
These incidents had raised questionsabout the DC TENS design, particularly
its cargo door system, because therewere two incidents involving the
cargo door, however, modificationswere made, and by 1979, the aircraft
(07:39):
was considered safe and reliable.
So, hey, there you go.
American Airlines Flight 1 91 wasscheduled to depart O'Hare International
Airport in Chicago at 3:00 PM localtime on Friday, May 25th, 1979.
The start of Memorial Day weekend,its destination was Los Angeles
(08:03):
International Airport going to LApretty lax on that name if you ask me.
Oh boy.
And the X name cardigan.
You like that?
Only because there's never a timewhere you're not wearing a cardigan.
I actually love a good cardigan.
You're kind of wearing one right now.
I am.
(08:23):
Zach, have you ever flownin or out of O'Hare?
No.
Okay.
This is exciting because today, folksthat we are recording this episode, I
booked Zach and I a flight to ChicagoO'Hare, and I didn't know that I
was gonna do this episode tonight.
I was stuck between a coupleand then I was like, oh.
I should do an O'Hare episode becauseZach and I are going to O'Hare.
(08:47):
It'll be my like fifth timeat O'Hare in eight weeks.
But that's, that's my life.
Also it's the start ofMemorial Day weekend and we are
what the, is the house collapsing?
That's the sound when our air kicks on.
(09:07):
That's fucking insane.
That's gonna be crazy.
Listen back to these mics.
Wow.
Okay.
So this is happening onFriday, May 25th, 1979.
And we are recording literallythat same week, but it is
2005, so that's pretty fun.
(09:28):
It's 2025.
Yes.
What did I say?
It was, it's 2005.
It's not, it's 2025.
It's definitely not.
It's definitely not.
You were 12, The flightwas completely full.
Of course it was.
Of course it was.
It's Memorial Day weekend, oneof the highest traveling weekends
in the country, and I guess italso was back in 1979 as well.
(09:53):
With 258 passengers and 13 crew members.
Many were heading to California forvacation, others for business meetings.
Family visits or connecting flights todestinations across the Pacific in command
of the flight was kept in Walter Lux 53,an experienced pilot with right around
(10:18):
22,000 flying hours and he had 3000.
Specifically in the DC 10, he was joinedby first officer James Dillard, who
was 49, and flight engineer Alfred Vic.
56.
Between them, they had over 46,000hours of flying experience equivalent
(10:40):
to more than five years in the air.
I always love doing that math.
That's why I include it inevery episode 'cause it's like
really crazy to think about.
first officer James Dillard, Wouldbe the pilot flying for this leg.
He is going to handle the physicalcontrols during takeoff and landing,
while Captain Walter would serveas pilot monitoring, handling
(11:05):
communications and system management.
The weather that Friday afternoonwas nearly perfect for flying
clear skies, good visibility,and only very light winds.
Flight 1 91 pushed back from thegate at 2:45 PM and taxi to runway
32 R which actually is 32, right?
(11:27):
Guys, I'm gonna let youin on a little secret.
I am very fascinated by the signsthat are, when you're taxiing and
you look out the window and you justsee like numbers and letters, and
to somebody like me, it's gibberish.
It makes absolutely no sense,but I am going to figure it out.
(11:47):
Would you like to know what C is?
I'm gonna, I'm gonnathrow a curve ball at you.
Are you gonna tell me what L is by chance?
I'm not gonna tell you.
I'm gonna make you guess.
Oh.
Hmm hmm.
I don't know.
Is it Larry?
It's Lima.
Okay.
After a brief wait in the departure queue,it was cleared for takeoff at 3:02 PM As
(12:10):
the DC 10 accelerated down the runway,everything seemed completely normal.
The three engines roared at fullpower pushing the massive aircraft
forward as it gathered speed.
James guided the controls whileWalter monitored the instruments and
called out the airspeed checkpoints.
V one Walter would've called asthey reached the decision speed
(12:34):
of approximately 145 knots,which is 167 miles per hour.
This is a critical point in any takeoff.
It's the speed at which the pilotsmust commit to becoming airborne
as there is literally not enoughrunway to slow down at that point.
So once you hit that, it's likeyou're in it, you're committed.
(12:58):
Next came the rotation.
Call VR James Polt, back on thecontrol column, he raises the nose
of the DC 10 to get it to take off.
As the aircraft reached V two,which is the safe climbing speed.
It lifted off the runwayand began its initial climb.
So anybody that has been in anairplane has experienced all of that.
(13:23):
When the plane sort of feelslike it naturally is, is
lifting off of the runway.
However, this moment, which in typicalflying is exciting, uneventful,
it would go catastrophically.
Wrong justice flight 1 91 was liftingoff the runway, the number one engine,
(13:45):
which is the one on the left wing.
And its entire mounting pylonsuddenly separated from the aircraft.
That's not what you want from what I hear.
No.
This was not just a component failure.
The entire engine assembly weighingseveral tons tore away from the wing.
(14:08):
This is actually like a hugefear that I have anytime that
I'm sitting in the windows.
It's one of the reasons why I try notto sit in the window seat because I,
I look out and I obsess over everymovement of every component on the
airplane, and I'm constantly like,is it supposed to bend like that?
Is it supposed to wiggle like that?
Does it move like that?
That's my brain.
(14:29):
Well, in this case, the answer is no.
The site was actually capturedby witnesses on the ground.
Robert Graham, a maintenancesupervisor for American Airlines who
happened to be watching the takeofflater described what he saw, quote.
I noticed that the number one enginewas bouncing up and down quite a bit,
(14:49):
and just about the time the aircraftgot opposite my position and started
rotation, the engine came off, wentup over the top of the wing, and
rolled back down onto the runway.
That must have been so insane to see.
At least it landed in the runway though.
I mean, that is a heavy chunk of metal.
(15:10):
That is, yeah.
That would've fucked some shit up.
Mm-hmm.
As Robert observed, the enginedidn't simply fall downward.
The aerodynamic forces actuallycaused it to move upward and back
following the aircraft over thewing before crashing onto the runway
behind the still climbing aircraft.
(15:30):
Now, it is important to understandthat modern aircraft are designed to
fly safely, even if an engine fails.
Mm-hmm.
Pilots regularly train for enginefailures, and the DC 10 with its three
engines should have been able to climb,circle back, and land safely, even
(15:50):
with the loss of one of the engines.
But this was not an engine failure.
Yeah.
The, the weight by itself would haveto throw everything all outta whack.
You are absolutely correct the fact thatsomething that weighed 14,000 pounds.
Mm-hmm.
Yeah.
When the engine tore away, ittook with it a three foot section
(16:13):
of the wing's leading edge.
As well.
It also severed hydraulic lines thatcontrolled essential flight systems,
including the leading edge slats.
So these slats are panels onthe front edge of the wing that
extend during takeoff, right?
We've that's sat near the wingsof an airplane has probably seen,
(16:37):
they literally look like slats.
They're like, and I know every time Imake those sound effects, but I don't
really know how else to like explain it.
She does real good sounds, everybody,you know, it's like a little transformer.
It just like pops out and then itcan retract back into the wing.
(16:58):
Well these are ripped off.
Um, Less than ideal.
Yes.
So think of them like the flapsthat you might see extending from
the rear wings during landing.
Except these ones are at the front of thewing, not the rear, not on this plane.
They're not, they, when the hydrauliclines were severed, the slats on the
(17:21):
left wing's, outer section retracteddue to the force of the airflow.
While the slats on the right wing remainedextended, it created extreme asymmetry.
Let's talk about the deadly asymmetry.
Super asymmetry.
It is.
The left wing now required a higherspeed to generate the same lift as the
(17:46):
right wing, and that's not possible on anaircraft where it doesn't have an engine.
And yeah, Specifically with theslots retracted, the left wings stall
speed, the minimum speed needed togenerate sufficient lift increased.
From about 124 knots to 159 knots.
(18:09):
But the aircraft was only at 153.
The standard takeoff safety speed.
So let me break this down 'causeI know this is a lot of like
industry jargon and blah blah blue.
The airplane was now flying tooslowly for its left wing to generate
enough lift while the right wingwas still producing plenty of lift.
(18:34):
This imbalance caused theaircraft to roll to the left.
But the problems did not end there.
The engine separation also damagedthe aircraft's electrical system.
So when the number one engine toreaway, it took with it the generator
that powered several critical systems,including the captain's instrument panel.
(19:00):
That's right.
Zach, would you say that that'simportant in flying an aircraft?
No, probably not.
I also don't watch my Speedo as I'mdriving down the road, but whatever.
I can imagine though that the captainis watching this thing like a hawk,
and then all of a sudden it's black.
I'm like, whoa, bad, bad.
It also took out the stallwarning system and the slat
(19:21):
disagreement sensors as well.
This meant that the pilots had nowarning that the slats on the left
wing had retracted, and they alsodid not receive a stall warning as
the left wing began to lose its lift.
So this all happened very quickly.
And then the plane is just rolling.
(19:42):
That's, that's wild.
Had they known about the slatretraction, they may have been able to
increase their air speed to compensate,which would have avoided the stall.
Not sure if that's possible, but acouple places said though, like, well,
maybe we don't, we don't know, but.
I just don't think that there would'vebeen enough reaction time because they
(20:04):
don't even know what the problem is.
That's so true.
That's so true.
But guess what we have that we canuse to help put together this puzzle.
Zach?
An orange box.
We do Maybe even a green box.
No, it's orange, purple box.
What the cockpit voice recorder capturedin these moments is really haunting.
(20:28):
Unlike modern aircraft, which record hoursof cockpit audio, the CVR on this DC 10
operated on a continuous 30 minute loop.
When the engine separated, itdamaged the electrical system
that powered the recorder.
So only the sound of the engineseparating And James Exclaiming Dam.
(20:51):
We're captured before the recording ended.
That's what he had to say.
This whole thing's feelingquite funky in the air.
He's like, damn, stop.
Guess it's time to go down.
Stop suck.
Maybe he's not a swearer.
We don't know.
That could be like areally big deal for him.
That would've immediately justgone for like shit or fuck.
(21:13):
Okay, but not damn.
Okay, this loss of the CVR recordingmight seem unfortunate for investigators,
but it actually provided very valuableinformation about exactly which
electrical circuits had failed asa result of the engine separation.
As the aircraft continued to climb,reaching around 325 feet above the ground.
(21:40):
Witnesses reported seeing a white misttrailing from the left wing, a combination
of leaking fuel and hydraulic fluid.
The crew was likely followingstandard engine failure procedures,
maintaining the takeoff speed of 153knots as specified in their training.
(22:00):
But with the left wing stallspeed now at 159 knots.
This was six knots.
Too slow.
Yep.
Right on edge.
Yeah.
What is it?
A something and a dollar short.
A day late and a dollar short.
A daily and a dollar short.
And six knots too slow.
The result was inevitable.
(22:21):
The left wing stalled and stoppedproducing lift while the right
wing continued to lift normally.
And this imbalance is whatcaused the aircraft to roll
rapidly to the left flight.
1 91 banked more and moresteeply, eventually rolling
to an angle of 112 degrees.
(22:43):
Which is nearly upside down.
I mean, that's past.
90 degrees math, geometry.
I, I got that.
Thank you.
Thank you.
No, I just wanted to makesure that you were following.
Okay.
With the right wing pointed,almost straight up into the sky,
as the roll continued, the nosedropped and the aircraft began
(23:04):
its final unrecoverable dive.
Did I say that?
As the role continued, the nosedropped in the aircraft began
its final unrecoverable dive.
Do you feel like you said it already?
I do.
You did.
Just 31 seconds after lifting off abouthalf a minute of what must have been
(23:24):
absolute terror in both the cockpitand the cabin American Airlines Flight
1 91 slammed into an open field only4,600 feet from the end of the runway.
The impact point was in thecommunity of de Plaines de plane
(23:47):
de planes fell down.
It did indeed.
De plane go, boom.
It was near a trailerpark and an old, damn.
Get this an old aircraft hanger.
The aircraft was destroyed by theimpact and the subsequent fire fueled
by nearly 21,000 gallons of jet fuel.
(24:08):
Large sections of debris were hurled intothe adjacent trailer park, destroying
five trailers and several cars.
The crash site was just northwestof the intersection of toy
Avenue and Mount Prospect Road.
I have been on Toy Road.
Yes, you have.
. All 271 people aboard died instantly.
(24:32):
Two people on the ground were alsokilled, and several others were injured.
This disaster remains the deadliestaviation accident in US history.
Let's talk about the investigation, Zach.
What the actual hellhappened on this plane?
Damn, damn, damn is right.
What the damn happened?
(24:52):
What the damn happened?
The National Transportation Safety Boardimmediately launched what would become one
of the most extensive investigations ever.
With 273 lives lost, they neededto determine exactly what had gone
wrong and how to prevent similartragedies from happening in the future.
(25:13):
One of the first questions thatinvestigators faced was whether
the aircraft had struck a foreignobject on the runway that may have
caused the engine to come loose andultimately detach from the aircraft.
I could see the logic.
Yeah.
But also now, yeah, we know that thatdidn't happen, but also because nothing
(25:36):
like this had ever happened before.
I think they're literallyjust grasping at straws.
They're like, what the fuck happened?
Yeah, but it also doesn't make sense.
You and the witnesses are in agreement.
Nothing had struck the aircraftduring its takeoff role.
Additionally, when they examinedthe separated engine on the runway.
(25:56):
Investigators found no signs ofimpact, damage, or bird strikes.
This left structural failureas the most likely cause.
But why would a relatively youngaircraft just seven years old and
well-maintained experience such acatastrophic structural failure?
(26:18):
The answer began to emerge wheninvestigators examined the pylon
attachment points on the wingand the corresponding fittings
on the separated engine pylon.
So when we were using the termpylon, think about this like you're
assembling IKEA furniture, you know,and there is a spot where the bookshelf
(26:44):
goes and you screw the bookshelfin from, you know, the outside.
Of the walls of the bookshelf.
It's a riff nut.
It's, yes.
So this is basically saying thatthere are, there is a base to this
engine and that gets attached tothe wing and they are designed to
(27:06):
fit together and stay attached.
Like a glove.
Like a glove.
And the pylons on both the wing andthe engine are being examined to
figure out how they got separated.
Gotta keep 'em separated.
Well, no, this, no, actuallythese need to be together.
(27:31):
So they found that damage tothe wings pylon mounting bracket
matched the bent shape of thepylons rear attachment fitting.
I know that's like a lot to take in, butwhat this means is that the pylon fitting.
Had struck the mounting bracketat some point, so stick with
(27:53):
me because this is important.
The only way the pylon fittingcould strike the wings mounting
bracket in the observed manner wasif the bolts that held the pylon to
the wing had already been removed
and the engine pylon assemblywas being supported by something
(28:16):
other than the aircraft itself.
Y'all, this is insane.
This pointed to a maintenanceissue and a big one.
Rather than an in-flight failure, theNTSB determined that the damage to the
left wing engine pylon had occurred duringan engine change at American Airlines
(28:36):
Maintenance Facility in Tulsa, Oklahoma.
Between March 29th and 30th,1979, only eight weeks before the
crash, it held on for eight weeks.
Yes.
When things were put together correctly.
Yes.
Planes are so safe, y'all.
Let me explain, Zach and listeners, whatshould have happened versus what actually
(29:01):
did happen during this maintenance.
The DC tens engines are attached tothe wings by structures called pylons.
And if you're playing a drinking gameand you are drinking pylon, every time
I say pylon, you're gonna be sheistyby the end of this here episode.
The manufacturer, McDonald Douglashad a specific procedure for
(29:25):
removing engines during maintenance.
First, detach the engine from its pylonand then remove the pylon from the wing.
I'm trying to think if there's like acar analogy that we could make for this.
Yeah, you have to remove the motormount from the engine, and then
you remove the motor mount from thesub frame to get the motor mat out.
(29:46):
That's perfect, Zach.
It's just like that, people.
I'm perfect.
Oh my God.
Okay.
this method required disconnecting79 different connections.
Things like hydraulic lines, fuellines, electrical cables, and wiring.
(30:08):
So all that shit's in the way,and you gotta disconnect all
of it in order to do this job.
That's a big job.
I wonder what the hourscall for on, on that one.
I can see you doing math in your head.
I have 22 connectors on my engine.
Mm-hmm.
And that includes thealternator and the starter.
(30:28):
Okay.
So, I mean, honestly, are weshocked that there's so few?
If, if a car has that many, well,that's my very simplified car.
Yeah, I, that's fair.
Because mine also has one plugfor all four coils per side.
Oh boy.
People are gonna be like,what the fuck is going on?
(30:50):
This is a very technical episode.
Okay.
We're gonna keep chugging along though.
American Airlines.
Along with Continental Airlinesand United Airlines had developed
a different procedure that savedalmost 200 work hours per aircraft.
So what is this magical method you mightbe asking that's going to save 200 hours?
(31:12):
Just disconnect the pylon.
Instead of removing the engine andpylon separately, they would remove
them together as a single unit.
This reduced the number of disconnectionsfrom 79 to only 27, which not only
saved time, but theoretically shouldhave reduced the risk of errors in
(31:34):
reconnecting all of those systems.
The method that United Airlinesused involved an overhead crane to
support the engine or pylon assemblyduring removal and reinstallation,
literally an engine crane.
Yeah.
Like what we have, buton absolute steroids.
A bolt's, a bolt.
A bolt's, a bolt, baby.
However American and Continental used alarge forklift to support the assembly,
(32:01):
and this is where the problem begins.
A, when using a forklift to supportthe engine and pylon assembly
positioning had to be extremely precise.
Forklift operators were guidedonly by hand and voice signals as
they couldn't even see the junctionbetween the pylon and the wing.
(32:21):
So they are working blind, right?
I mean, you gotta think they'relike way down on the ground, right?
Operating this huge forklift.
There's a mechanic working on the assemblylet's go back to the IKEA analogy.
Even that basic, you know, you have toline up the hole to get the bolt in.
(32:44):
That's a pretty key part of this,except this is an airplane engine
in a forklift being involved.
If the forklift was not positionedcorrectly, the engine pylon
assembly could rock and jam againstthe wing's attachment points.
And unfortunately that isexactly what happened during the
(33:04):
maintenance on this airplane.
The mechanics started disconnectingthe engine and pylon as a
single unit, but a shift changeoccurred halfway through the job.
Mm.
During this interval, even thoughthe forklift remained stationary, its
forks supporting the engine weight ofthe engine and pylon moved downward
(33:26):
very slightly due to a normal loss ofhydraulic pressure associated with the
forklift's engine being turned off.
Well, I tell a lot of people,not so many hands in the cookie
jar means less lost bolts.
That's so true.
It's so true.
Oh boy.
Well, Zach, this slight movement causeda misalignment between the engine
(33:50):
pylon and the wing when work resumed.
The pylon was jammed against the wingand the forklift had to be repositioned.
The resulting stress caused damage to thepylon attachment structure, damage that
was not immediately apparent and didn'tcause an immediate failure, but eventually
(34:10):
developed into fatigue, cracking this,cracking worsened with every takeoff
and landing cycle during the eightweeks that followed The aircraft flew
approximately 200 flights after this,before the attachment finally failed.
Yeah, so this is already pretty nuts,but there is actually more to this story.
(34:33):
The investigation revealed that AmericanAirlines was not alone in these practices.
Inspections of the DC 10 fleets atmultiple airlines revealed that several
aircraft also had fatigue, cracking,and damage to their pylon mounts.
Oh, this was about to happenagain and again and again.
(34:54):
Mm-hmm.
Mm-hmm.
Caused by similar maintenance procedures.
When confronted with evidence of thesemaintenance shortcuts, McDonald Douglas
stated they quote, would not encouragethis procedure due to the element of
risk end quote, and had so advisedAmerican Airlines, so they basically were
(35:15):
like, we told them they did it anyway.
Nah.
However, pass the buck.
I mean, they did.
They admitted that they, quote, didnot have the authority to either
approve or disapprove the maintenanceprocedures of their customers, end quote.
And that really is the true case.
Like once Boeing, once you know McDonald,once these guys sell the airplanes,
(35:38):
it's up to the airlines todo the maintenance on them.
I mean, I'm not gonna stop doingsomething because Toyota tells me not to.
Oh, folks, that's a true statementgosh, not OSHA approved, or
Toyota or anyone approved.
This statement highlights a fundamentalissue in aviation system safety oversight.
(36:02):
The division of responsibility betweenmanufacturers, airlines, and regulatory
agencies like the FAA, speaking of theFAA, the investigation found that they
had failed to detect and prevent the useof these improper maintenance procedures.
There were deficiencies in theirsurveillance and reporting systems
(36:25):
that should have caught theseissues before they led to disaster.
Mm-hmm.
Mm-hmm.
Beyond the maintenance issues,the NTSB also investigated why the
loss of one engine and a sectionof the leading edge had led to such
a catastrophic loss of control.
After all, the DC 10 was designed tofly safely with one engine in operative.
(36:50):
Now, you know, obviously having anentire engine removed is pretty extreme
in comparison to just one of themstopping, you know, thrust not working.
The key factor was the slatretraction on the left wing.
So unlike some other aircraft designs,the DC 10 did not have a separate
(37:13):
mechanism that would lock the extendedleading edge slats into place.
So it relied on hydraulic pressure tokeep them extended when those hydraulic
lines were severed airflow over thewing, forced the left wing slats to
retract, sucked that thing right back in.
(37:35):
Straight up Turtled.
And airflow over the wing, forced leftwing slots to retract, causing the
aerodynamic asymmetry that ultimatelyled to the stall and the roll.
I am like, I'm sofascinated by all of this,
I have so much to learn.
I feel like I need to go tolike flight school or something,
but instead I'm just going to.
(37:58):
Ignorantly tell people about things thatI am not qualified to tell them, which
is really the name of this podcast.
We're Americans.
That's what we do.
I mean, we're just ignored Americans.
It's thin.
The NTSB conducted wind tunnel andflight simulator test to understand the
aircraft's behavior over the engine.
(38:18):
Oh, after the engine detached and theleft wing slots retracted, those tests
confirmed that the damage to the wings,leading edge and retraction of the
slots had increased the stall speedof the left wing from 124 knots to 159
knots making a stall inevitable at thespeed that the aircraft was flying.
(38:41):
So nothing they could havedone, like that's, that's
what that all boils down to.
Mm-hmm.
Final critical finding here,Zach, the warning systems.
That should have alerted thepilots to the impending stall.
The DC 10 had two systems, the slotdisagreement, warning light, which
(39:06):
should have illuminated after theun uncom commanded retraction of
the S slaps and the stick shaker onthe captain's control column, which
activates close to the stall speed.
So that should have given a littleshake, the the control column.
And then obviously this lightshould have illuminated.
However, these were both poweredby the electric generator, which,
(39:29):
Separated was not generatingSo after months of meticulous
investigation, the NTSB released itsfinal report on December 21st, 1979.
The verdict was clear.
The crash had been caused bychain of events stemming from
improper maintenance procedures.
The immediate cause was the in-flightseparation of the engine and the
(39:52):
pilon assembly, but the root causeextended to design vulnerabilities,
maintenance shortcuts, andregulatory oversight failures.
Okay, let's talk about what,what they did about this.
I mean, this is the biggestcrash in US history.
So something better happened, right?
(40:15):
You think?
Yeah.
On June 6th, 1979, this isonly two weeks after the crash.
The FAA took the unprecedentedstep of grounding the entire DC
10 fleet in the United States.
It also banned foreignDC tens from US airspace.
(40:36):
So DC 10 is not in theair in the United States.
This was a dramatic move that strandedthousands of passengers worldwide and
cost airlines millions of dollars.
That is 1979 millions of dollars.
(40:56):
The grounding order was a severe blow,obviously, to McDonald Douglas, which
had marketed the DC 10 as one of the mostadvanced and safest aircraft in the sky.
But the dramatic photos of Flight 1 91with its engine missing captured moments
before the crash were published innewspapers worldwide and really became
(41:20):
an iconic image of aviation disaster.
The DC ten's reputation alreadydamaged by the earlier cargo door
incidents took a massive hit.
The aircraft wasnicknamed Death Cruiser 10
and clever.
(41:41):
It's so bad.
So bad.
Oh, man.
Yeah.
So instead of DC Death Cruiser, mm-hmm.
Wild.
And passenger confidence plummeted.
Several airlines reported the passengerswere specifically requesting to not fly
on DC tens when they were booking flights.
(42:05):
Y So they were groundeduntil July 13th, 1979.
So that's five weeks.
In which case, they also found12 others that were damaged.
No.
The FAA ultimately was satisfied that theissue was primarily related to maintenance
procedures rather than an inherentdesign flaw with the airplane itself.
(42:29):
However, the Yeah.
But you said they found others with the
stress fractures, yes.
So they, they looked at the DCtens, but they had to make sure
that it wasn't like an all DC tens.
Mm-hmm.
You know, this is a problem with theaircraft itself, and it wasn't the DC 10.
In theory was very safe.
It was the way that they were beingmaintained that was problematic.
(42:51):
However, the aircraft's type certificatewas amended to state explicitly removal
of the engine and pylon as a unitwill immediately render the aircraft.
OnAir unairworthy.
Wow.
Boom, boom.
That's like when you buy a mattressand it says, don't rip off the tag.
Do not rip off this attack,except this is an airplane.
(43:14):
I rip off that tag every time.
Subject to prosecution.
Subject to prosecution.
Okay, let's talk about whathappened to American Airlines.
Pit Bull.
He loves being a part of this podcast.
He's really a, a key figure.
The people love him.
P Bull problems.
Okay.
American Airlines was fined a measly$500,000 by the US government for
(43:39):
improper maintenance procedures, whichin my opinion is just like, what?
What on Earth?
It's literally a little slap on the hand.
I'll slap you down to thisslap that was naughty.
So $500,000.
I'm not gonna make you play this game,Zach, in 1979, money is equivalent to
(44:00):
around $2 million in today's money, whichstill in my opinion, is just like you
picture the money that they're making.
Fucking kidding me, kidding me.
These companies make $2 million a day.
They make much dollars.
So for me, that just isnot significant at all.
The human toll within the maintenanceorganization was also very severe.
(44:22):
Earl Russell Marshall, a crew chiefat Americans Tulsa Maintenance
facility who had been involved inthe maintenance procedure on that
particular plane, died by suicide thenight before he was scheduled to be
deposed by McDonald Douglas attorneys.
So that is, I mean,that's really horrible.
(44:44):
And you know, whatever his, hisinvolvement with this was obviously
you know, it's, it's another lifethat was taken by this crash.
The crash led to significantdesign and procedural changes
in the aviation industry.
In response to the accident, slat reliefvalves were mandated to prevent retraction
(45:06):
in case of hydraulic line damage.
Sounds logical.
You don't want things retracting whenthey shouldn't be retracting true.
That.
I mean, it's as simple as that.
You don't need to be a, you know,airline mechanic to figure that one out.
The FAA also required that stickshakers be in installed for both
pilots, not just the captain.
Mm-hmm.
(45:26):
The stick shaker.
I shake my stick with you.
I stick my stick shake.
Shake my stick.
All righty.
Airlines worldwide revised theirmaintenance procedures, abandoning
the practice of removing theengines and pylons as a single unit.
McDonald Douglas issued servicebulletins to improve the pylon
(45:47):
attachment design and provided detailedguidelines for proper maintenance
procedures for the victim's families.
The path to closure was long andpainful for 32 years, the victims had
no permanent memorial at the crash site.
But finally, in 2011, a memorialwas dedicated through the
(46:11):
efforts of a sixth grade class.
From a school in Chicago, the memorial,a two foot high concave wall with
interlocking bricks, displaying thenames of the crash victims is located
on the south shore of Lake O Peka,about two miles east of the crash site.
(46:34):
And Zach and I obviously will go andvisit this memorial and, and pay homage
to the victims of this terrible incident.
You didn't even know that was onthe itinerary, but it's happening.
I just hate that there's somuch of an itinerary already.
I agreed to this trip today.
I had the itinerary written months ago.
Despite the immediate impact on itsreputation, the DC 10 eventually recovered
(46:59):
and continued to serve passenger airlinesfor over three decades after the crash.
Production ended in 1988, but many DCtens were later converted to cargo use.
The last passenger DC 10 flight wasoperated by Biman Bangladesh Airlines,
in February 2nd, 2014, marking the end ofan era that spanned more than 40 years.
(47:25):
The crash of Flight 1 91 changed how theaviation industry approaches maintenance
procedures and regulatory oversight.
It highlighted the need for bettercommunication between the manufacturers,
the airlines, and the regulatory agencies.
That is so important and so critical.
If there is something that theairlines should not be doing to
(47:47):
maintain an airplane, they haveto know what they shouldn't do.
They have to know.
They have to know.
Yeah, it's just wild.
It led to improved warning systems andredundancies in critical flight control
systems as well, and it underscored theimportance of considering the potential
consequences of maintenance shortcuts.
(48:08):
No matter how time or cost effectiveit might seem for the airline,
you cannot be cut in them corners.
This disaster also changed howwe think about aircraft design.
Modern airliners now incorporate waymore fail safe systems and redundancies
to prevent a single failure fromleading to catastrophic consequences.
(48:30):
This was obviously the worstairline disaster as far as
fatalities go in the United States.
And it changed a lot of stuff.
It had some pretty importantrippling lessons learned.
Okay, Zach, that is our story for today.
Any thoughts?
Well,
(48:53):
damn.
I know Sounds fucking heavy, huh?
And very technical.
I like the technical side of things,but that's probably just 'cause
I am mechan or whatever you are.
But I'm glad that you could geekout on this one and hopefully some
of our listeners also geeked out.
Hopefully I did an okay job ofexplaining the, the do hinges that
(49:15):
connect to the other do hinges.
Well people, if you enjoyed thisepisode, please rate, review, subscribe
wherever you get your podcasts.
We are on Instagram, we are on Facebook.
We have a discussion group and wewould love to hear your thoughts.
So comments, message us,email us, do your thing.
Someone talk to us, somebody.
(49:38):
Is anybody out there?
And please join us next timewhen we will be exploring another
transportation disaster story.
Until then, remember to stow your traytables, fasten your seat belts, and
prepare for the unexpected, because notevery trip reaches its final destination.
(50:02):
Good.
Uh,
Good one, Zach.
Picture this.
A beautiful spring afternoonat Chicago's O'Hare Airport.
A fully loaded American Airlines DC 10thunders down the runway beginning what
should be a routine flight to Los Angeles.
As the massive jet liner liftsoff, something unthinkable happens.
(00:20):
The left engine rips away fromthe wing flipping up and over.
Before crashing back down onto the runway.
The stricken aircraft continuesto climb, trailing a mist
of leaking hydraulic fluid.
And fuel.
We're about to experience whathappens when a mechanical failure
(00:41):
caused by a maintenance shortagetriggers the deadliest air
disaster in American history.
So stow your tray tables, fastenyour seat belts, and prepare for
some extreme turbulence becausethis is final boarding call.
(01:03):
Hello and welcome to Final Boarding Call.
I am your disaster obsessed host Alice.
And I am Zach, who's not near as reluctantthese days, but today a little tired.
Zach, a reminder for thepeople before we dive in.
Please like, rate, review andsubscribe wherever you get your
(01:24):
podcasts, you're getting reallygood at your one queued line.
That's like the rest of the showfor Zach is completely unscripted.
But that's like, you know, you gottathrow the dog a bone every once in
a while except I don't get a script.
It'd be easier if I did.
You have an insane memory.
You absolutely do not need one period.
(01:44):
Maybe I won't.
One.
And that's a fact . let's talksources before we dive in.
A so the sources for thisepisode there are a handful.
So there is a,
I don't know what you're doing withyour hand, but you're making me nervous.
I'm waiting to count.
You said a handful.
Oh my God.
Oh my God.
(02:05):
Zach just literally put a fistin the air and I was like,
is this the, is this the day?
Is it going down for realright now on the podcast?
While recording was the first timeI struck someone that's struck
my wife, I was to struck a woman.
Definitely struck peoplefor, okay um, sources.
(02:25):
What caused the crash of AmericanAirlines Flight 1 91 by simple flying.
and the article was written byJake Hardiman and Luke Bode.
Obviously Wikipedia has aton of information on this.
There is a Nat Geo documentary actuallyon this as well, called Seconds
From Disaster Chicago Plane Crash.
(02:48):
There is a Smithsonian Channeldocumentary on this crash as well.
M-S-N-B-C-Y planes Crash.
Season one, episode two.
I know I've got a lot for this one,but it's because it is the deadliest
aviation disaster in the United States.
So that's big.
Here we go.
To understand the disaster ofAmerican Airlines Flight 1 91.
(03:11):
We first need to understand theaircraft, the McDonald Douglas, DC 10.
So Zach, we are in the 1970s.
We're back.
It seemed to be a decade of alot of plane shit going down.
The DC 10 represented the cuttingedge of aviation technology.
(03:37):
This bad girl was a wide body, three jet,three engine jet liner that was designed
to compete with the Boeing 7 47, whichwe are extremely familiar with, right?
The Boeing 7 47, an economyclass is a 10 seater aircraft.
It has the little upper deck thing thatwe've talked about where like there
can be cool stuff up there or nothing.
(04:00):
I've never been up there so.
We're gonna pretend it's nothing'cause we don't get to go there.
I know in my head it's like an aquarium.
It's definitely not that Iknow, but in my head it's, so
the DC 10 might sound familiar to ourlisteners because we did talk about a
DC 10 in our Japan Airlines Flight 9 07 and 9 5 8 episode, which involved a
(04:24):
Boeing 7 47 and a McDonald Douglas, DC 10.
And interestingly enough, thatincident specifically takes
place in January of 2001.
So how crazy is it that the episodewe're covering today is in the seventies?
And we covered another DC 10episode that took place in 2001.
(04:48):
Okay.
Anyway, so with its distinctive threeengine configuration, one under each
wing, and one mounted in the tail, theDC 10 could carry up to 380 passengers
and fly intercontinental routes.
So very similar to the 7 47.
(05:10):
The specific DC 10assigned to flight 1 91.
That day was registrationnumber N 11 zero aa.
It had been delivered to AmericanAirlines in February of 1972,
and it had logged just under20,000 hours of flying time over.
(05:30):
Its seven year service life.
So it's not old.
It's not new, but it isn't likearchaic, you know, I don't think
seven years for and for a plane.
Is that crazy?
20,000 miles.
(05:50):
I mean, I don't know.
20,000 hours or, yeah, sorry.
20,000 hours.
Pilots let us know it was poweredby three General Electric CF six
engines, so that's actually interesting.
I didn't know that General Electric made.
Plane engines.
Did you know that when I thinkof ge I think of a washing
(06:11):
machine or a refrigerator.
My mind does not go to plane engine.
Well, you have to picture once upona time, anybody that was making all
of these I guess technology basedinstruments of sorts, Yamaha made
motorcycles and musical instrumentsand engines and all kinds of stuff.
(06:32):
That's fair.
That's fair.
So each of these engines was capable ofproducing over 40,000 pounds of thrust.
So that's like having the powerof around 800 family cars in
each engine, and it had three.
What kind of family carare we talking about?
Don?
(06:52):
Are we talking about don't theseventies where they had a small
block Chevy, small block Chevy
but the DC 10 had alreadyexperienced some troubling incidents.
In 1972, a cargo door blew outon American Airlines flight 96.
And we are going to cover thatstory, so I'm not going to dive
into it too much, but know thatthat happened and it was bad.
(07:15):
Then in 1974, a nearly identicalproblem caused Turkish Airlines flight
9 8 1 to have an incident as well.
These incidents had raised questionsabout the DC TENS design, particularly
its cargo door system, because therewere two incidents involving the
cargo door, however, modificationswere made, and by 1979, the aircraft
(07:39):
was considered safe and reliable.
So, hey, there you go.
American Airlines Flight 1 91 wasscheduled to depart O'Hare International
Airport in Chicago at 3:00 PM localtime on Friday, May 25th, 1979.
The start of Memorial Day weekend,its destination was Los Angeles
(08:03):
International Airport going to LApretty lax on that name if you ask me.
Oh boy.
And the X name cardigan.
You like that?
Only because there's never a timewhere you're not wearing a cardigan.
I actually love a good cardigan.
You're kind of wearing one right now.
I am.
(08:23):
Zach, have you ever flownin or out of O'Hare?
No.
Okay.
This is exciting because today, folksthat we are recording this episode, I
booked Zach and I a flight to ChicagoO'Hare, and I didn't know that I
was gonna do this episode tonight.
I was stuck between a coupleand then I was like, oh.
I should do an O'Hare episode becauseZach and I are going to O'Hare.
(08:47):
It'll be my like fifth timeat O'Hare in eight weeks.
But that's, that's my life.
Also it's the start ofMemorial Day weekend and we are
what the, is the house collapsing?
That's the sound when our air kicks on.
(09:07):
That's fucking insane.
That's gonna be crazy.
Listen back to these mics.
Wow.
Okay.
So this is happening onFriday, May 25th, 1979.
And we are recording literallythat same week, but it is
2005, so that's pretty fun.
(09:28):
It's 2025.
Yes.
What did I say?
It was, it's 2005.
It's not, it's 2025.
It's definitely not.
It's definitely not.
You were 12, The flightwas completely full.
Of course it was.
Of course it was.
It's Memorial Day weekend, oneof the highest traveling weekends
in the country, and I guess italso was back in 1979 as well.
(09:53):
With 258 passengers and 13 crew members.
Many were heading to California forvacation, others for business meetings.
Family visits or connecting flights todestinations across the Pacific in command
of the flight was kept in Walter Lux 53,an experienced pilot with right around
(10:18):
22,000 flying hours and he had 3000.
Specifically in the DC 10, he was joinedby first officer James Dillard, who
was 49, and flight engineer Alfred Vic.
56.
Between them, they had over 46,000hours of flying experience equivalent
(10:40):
to more than five years in the air.
I always love doing that math.
That's why I include it inevery episode 'cause it's like
really crazy to think about.
first officer James Dillard, Wouldbe the pilot flying for this leg.
He is going to handle the physicalcontrols during takeoff and landing,
while Captain Walter would serveas pilot monitoring, handling
(11:05):
communications and system management.
The weather that Friday afternoonwas nearly perfect for flying
clear skies, good visibility,and only very light winds.
Flight 1 91 pushed back from thegate at 2:45 PM and taxi to runway
32 R which actually is 32, right?
(11:27):
Guys, I'm gonna let youin on a little secret.
I am very fascinated by the signsthat are, when you're taxiing and
you look out the window and you justsee like numbers and letters, and
to somebody like me, it's gibberish.
It makes absolutely no sense,but I am going to figure it out.
(11:47):
Would you like to know what C is?
I'm gonna, I'm gonnathrow a curve ball at you.
Are you gonna tell me what L is by chance?
I'm not gonna tell you.
I'm gonna make you guess.
Oh.
Hmm hmm.
I don't know.
Is it Larry?
It's Lima.
Okay.
After a brief wait in the departure queue,it was cleared for takeoff at 3:02 PM As
(12:10):
the DC 10 accelerated down the runway,everything seemed completely normal.
The three engines roared at fullpower pushing the massive aircraft
forward as it gathered speed.
James guided the controls whileWalter monitored the instruments and
called out the airspeed checkpoints.
V one Walter would've called asthey reached the decision speed
(12:34):
of approximately 145 knots,which is 167 miles per hour.
This is a critical point in any takeoff.
It's the speed at which the pilotsmust commit to becoming airborne
as there is literally not enoughrunway to slow down at that point.
So once you hit that, it's likeyou're in it, you're committed.
(12:58):
Next came the rotation.
Call VR James Polt, back on thecontrol column, he raises the nose
of the DC 10 to get it to take off.
As the aircraft reached V two,which is the safe climbing speed.
It lifted off the runwayand began its initial climb.
So anybody that has been in anairplane has experienced all of that.
(13:23):
When the plane sort of feelslike it naturally is, is
lifting off of the runway.
However, this moment, which in typicalflying is exciting, uneventful,
it would go catastrophically.
Wrong justice flight 1 91 was liftingoff the runway, the number one engine,
(13:45):
which is the one on the left wing.
And its entire mounting pylonsuddenly separated from the aircraft.
That's not what you want from what I hear.
No.
This was not just a component failure.
The entire engine assembly weighingseveral tons tore away from the wing.
(14:08):
This is actually like a hugefear that I have anytime that
I'm sitting in the windows.
It's one of the reasons why I try notto sit in the window seat because I,
I look out and I obsess over everymovement of every component on the
airplane, and I'm constantly like,is it supposed to bend like that?
Is it supposed to wiggle like that?
Does it move like that?
That's my brain.
(14:29):
Well, in this case, the answer is no.
The site was actually capturedby witnesses on the ground.
Robert Graham, a maintenancesupervisor for American Airlines who
happened to be watching the takeofflater described what he saw, quote.
I noticed that the number one enginewas bouncing up and down quite a bit,
(14:49):
and just about the time the aircraftgot opposite my position and started
rotation, the engine came off, wentup over the top of the wing, and
rolled back down onto the runway.
That must have been so insane to see.
At least it landed in the runway though.
I mean, that is a heavy chunk of metal.
(15:10):
That is, yeah.
That would've fucked some shit up.
Mm-hmm.
As Robert observed, the enginedidn't simply fall downward.
The aerodynamic forces actuallycaused it to move upward and back
following the aircraft over thewing before crashing onto the runway
behind the still climbing aircraft.
(15:30):
Now, it is important to understandthat modern aircraft are designed to
fly safely, even if an engine fails.
Mm-hmm.
Pilots regularly train for enginefailures, and the DC 10 with its three
engines should have been able to climb,circle back, and land safely, even
(15:50):
with the loss of one of the engines.
But this was not an engine failure.
Yeah.
The, the weight by itself would haveto throw everything all outta whack.
You are absolutely correct the fact thatsomething that weighed 14,000 pounds.
Mm-hmm.
Yeah.
When the engine tore away, ittook with it a three foot section
(16:13):
of the wing's leading edge.
As well.
It also severed hydraulic lines thatcontrolled essential flight systems,
including the leading edge slats.
So these slats are panels onthe front edge of the wing that
extend during takeoff, right?
We've that's sat near the wingsof an airplane has probably seen,
(16:37):
they literally look like slats.
They're like, and I know every time Imake those sound effects, but I don't
really know how else to like explain it.
She does real good sounds, everybody,you know, it's like a little transformer.
It just like pops out and then itcan retract back into the wing.
(16:58):
Well these are ripped off.
Um, Less than ideal.
Yes.
So think of them like the flapsthat you might see extending from
the rear wings during landing.
Except these ones are at the front of thewing, not the rear, not on this plane.
They're not, they, when the hydrauliclines were severed, the slats on the
(17:21):
left wing's, outer section retracteddue to the force of the airflow.
While the slats on the right wing remainedextended, it created extreme asymmetry.
Let's talk about the deadly asymmetry.
Super asymmetry.
It is.
The left wing now required a higherspeed to generate the same lift as the
(17:46):
right wing, and that's not possible on anaircraft where it doesn't have an engine.
And yeah, Specifically with theslots retracted, the left wings stall
speed, the minimum speed needed togenerate sufficient lift increased.
From about 124 knots to 159 knots.
(18:09):
But the aircraft was only at 153.
The standard takeoff safety speed.
So let me break this down 'causeI know this is a lot of like
industry jargon and blah blah blue.
The airplane was now flying tooslowly for its left wing to generate
enough lift while the right wingwas still producing plenty of lift.
(18:34):
This imbalance caused theaircraft to roll to the left.
But the problems did not end there.
The engine separation also damagedthe aircraft's electrical system.
So when the number one engine toreaway, it took with it the generator
that powered several critical systems,including the captain's instrument panel.
(19:00):
That's right.
Zach, would you say that that'simportant in flying an aircraft?
No, probably not.
I also don't watch my Speedo as I'mdriving down the road, but whatever.
I can imagine though that the captainis watching this thing like a hawk,
and then all of a sudden it's black.
I'm like, whoa, bad, bad.
It also took out the stallwarning system and the slat
(19:21):
disagreement sensors as well.
This meant that the pilots had nowarning that the slats on the left
wing had retracted, and they alsodid not receive a stall warning as
the left wing began to lose its lift.
So this all happened very quickly.
And then the plane is just rolling.
(19:42):
That's, that's wild.
Had they known about the slatretraction, they may have been able to
increase their air speed to compensate,which would have avoided the stall.
Not sure if that's possible, but acouple places said though, like, well,
maybe we don't, we don't know, but.
I just don't think that there would'vebeen enough reaction time because they
(20:04):
don't even know what the problem is.
That's so true.
That's so true.
But guess what we have that we canuse to help put together this puzzle.
Zach?
An orange box.
We do Maybe even a green box.
No, it's orange, purple box.
What the cockpit voice recorder capturedin these moments is really haunting.
(20:28):
Unlike modern aircraft, which record hoursof cockpit audio, the CVR on this DC 10
operated on a continuous 30 minute loop.
When the engine separated, itdamaged the electrical system
that powered the recorder.
So only the sound of the engineseparating And James Exclaiming Dam.
(20:51):
We're captured before the recording ended.
That's what he had to say.
This whole thing's feelingquite funky in the air.
He's like, damn, stop.
Guess it's time to go down.
Stop suck.
Maybe he's not a swearer.
We don't know.
That could be like areally big deal for him.
That would've immediately justgone for like shit or fuck.
(21:13):
Okay, but not damn.
Okay, this loss of the CVR recordingmight seem unfortunate for investigators,
but it actually provided very valuableinformation about exactly which
electrical circuits had failed asa result of the engine separation.
As the aircraft continued to climb,reaching around 325 feet above the ground.
(21:40):
Witnesses reported seeing a white misttrailing from the left wing, a combination
of leaking fuel and hydraulic fluid.
The crew was likely followingstandard engine failure procedures,
maintaining the takeoff speed of 153knots as specified in their training.
(22:00):
But with the left wing stallspeed now at 159 knots.
This was six knots.
Too slow.
Yep.
Right on edge.
Yeah.
What is it?
A something and a dollar short.
A day late and a dollar short.
A daily and a dollar short.
And six knots too slow.
The result was inevitable.
(22:21):
The left wing stalled and stoppedproducing lift while the right
wing continued to lift normally.
And this imbalance is whatcaused the aircraft to roll
rapidly to the left flight.
1 91 banked more and moresteeply, eventually rolling
to an angle of 112 degrees.
(22:43):
Which is nearly upside down.
I mean, that's past.
90 degrees math, geometry.
I, I got that.
Thank you.
Thank you.
No, I just wanted to makesure that you were following.
Okay.
With the right wing pointed,almost straight up into the sky,
as the roll continued, the nosedropped and the aircraft began
(23:04):
its final unrecoverable dive.
Did I say that?
As the role continued, the nosedropped in the aircraft began
its final unrecoverable dive.
Do you feel like you said it already?
I do.
You did.
Just 31 seconds after lifting off abouthalf a minute of what must have been
(23:24):
absolute terror in both the cockpitand the cabin American Airlines Flight
1 91 slammed into an open field only4,600 feet from the end of the runway.
The impact point was in thecommunity of de Plaines de plane
(23:47):
de planes fell down.
It did indeed.
De plane go, boom.
It was near a trailerpark and an old, damn.
Get this an old aircraft hanger.
The aircraft was destroyed by theimpact and the subsequent fire fueled
by nearly 21,000 gallons of jet fuel.
(24:08):
Large sections of debris were hurled intothe adjacent trailer park, destroying
five trailers and several cars.
The crash site was just northwestof the intersection of toy
Avenue and Mount Prospect Road.
I have been on Toy Road.
Yes, you have.
. All 271 people aboard died instantly.
(24:32):
Two people on the ground were alsokilled, and several others were injured.
This disaster remains the deadliestaviation accident in US history.
Let's talk about the investigation, Zach.
What the actual hellhappened on this plane?
Damn, damn, damn is right.
What the damn happened?
(24:52):
What the damn happened?
The National Transportation Safety Boardimmediately launched what would become one
of the most extensive investigations ever.
With 273 lives lost, they neededto determine exactly what had gone
wrong and how to prevent similartragedies from happening in the future.
(25:13):
One of the first questions thatinvestigators faced was whether
the aircraft had struck a foreignobject on the runway that may have
caused the engine to come loose andultimately detach from the aircraft.
I could see the logic.
Yeah.
But also now, yeah, we know that thatdidn't happen, but also because nothing
(25:36):
like this had ever happened before.
I think they're literallyjust grasping at straws.
They're like, what the fuck happened?
Yeah, but it also doesn't make sense.
You and the witnesses are in agreement.
Nothing had struck the aircraftduring its takeoff role.
Additionally, when they examinedthe separated engine on the runway.
(25:56):
Investigators found no signs ofimpact, damage, or bird strikes.
This left structural failureas the most likely cause.
But why would a relatively youngaircraft just seven years old and
well-maintained experience such acatastrophic structural failure?
(26:18):
The answer began to emerge wheninvestigators examined the pylon
attachment points on the wingand the corresponding fittings
on the separated engine pylon.
So when we were using the termpylon, think about this like you're
assembling IKEA furniture, you know,and there is a spot where the bookshelf
(26:44):
goes and you screw the bookshelfin from, you know, the outside.
Of the walls of the bookshelf.
It's a riff nut.
It's, yes.
So this is basically saying thatthere are, there is a base to this
engine and that gets attached tothe wing and they are designed to
(27:06):
fit together and stay attached.
Like a glove.
Like a glove.
And the pylons on both the wing andthe engine are being examined to
figure out how they got separated.
Gotta keep 'em separated.
Well, no, this, no, actuallythese need to be together.
(27:31):
So they found that damage tothe wings pylon mounting bracket
matched the bent shape of thepylons rear attachment fitting.
I know that's like a lot to take in, butwhat this means is that the pylon fitting.
Had struck the mounting bracketat some point, so stick with
(27:53):
me because this is important.
The only way the pylon fittingcould strike the wings mounting
bracket in the observed manner wasif the bolts that held the pylon to
the wing had already been removed
and the engine pylon assemblywas being supported by something
(28:16):
other than the aircraft itself.
Y'all, this is insane.
This pointed to a maintenanceissue and a big one.
Rather than an in-flight failure, theNTSB determined that the damage to the
left wing engine pylon had occurred duringan engine change at American Airlines
(28:36):
Maintenance Facility in Tulsa, Oklahoma.
Between March 29th and 30th,1979, only eight weeks before the
crash, it held on for eight weeks.
Yes.
When things were put together correctly.
Yes.
Planes are so safe, y'all.
Let me explain, Zach and listeners, whatshould have happened versus what actually
(29:01):
did happen during this maintenance.
The DC tens engines are attached tothe wings by structures called pylons.
And if you're playing a drinking gameand you are drinking pylon, every time
I say pylon, you're gonna be sheistyby the end of this here episode.
The manufacturer, McDonald Douglashad a specific procedure for
(29:25):
removing engines during maintenance.
First, detach the engine from its pylonand then remove the pylon from the wing.
I'm trying to think if there's like acar analogy that we could make for this.
Yeah, you have to remove the motormount from the engine, and then
you remove the motor mount from thesub frame to get the motor mat out.
(29:46):
That's perfect, Zach.
It's just like that, people.
I'm perfect.
Oh my God.
Okay.
this method required disconnecting79 different connections.
Things like hydraulic lines, fuellines, electrical cables, and wiring.
(30:08):
So all that shit's in the way,and you gotta disconnect all
of it in order to do this job.
That's a big job.
I wonder what the hourscall for on, on that one.
I can see you doing math in your head.
I have 22 connectors on my engine.
Mm-hmm.
And that includes thealternator and the starter.
(30:28):
Okay.
So, I mean, honestly, are weshocked that there's so few?
If, if a car has that many, well,that's my very simplified car.
Yeah, I, that's fair.
Because mine also has one plugfor all four coils per side.
Oh boy.
People are gonna be like,what the fuck is going on?
(30:50):
This is a very technical episode.
Okay.
We're gonna keep chugging along though.
American Airlines.
Along with Continental Airlinesand United Airlines had developed
a different procedure that savedalmost 200 work hours per aircraft.
So what is this magical method you mightbe asking that's going to save 200 hours?
(31:12):
Just disconnect the pylon.
Instead of removing the engine andpylon separately, they would remove
them together as a single unit.
This reduced the number of disconnectionsfrom 79 to only 27, which not only
saved time, but theoretically shouldhave reduced the risk of errors in
(31:34):
reconnecting all of those systems.
The method that United Airlinesused involved an overhead crane to
support the engine or pylon assemblyduring removal and reinstallation,
literally an engine crane.
Yeah.
Like what we have, buton absolute steroids.
A bolt's, a bolt.
A bolt's, a bolt, baby.
However American and Continental used alarge forklift to support the assembly,
(32:01):
and this is where the problem begins.
A, when using a forklift to supportthe engine and pylon assembly
positioning had to be extremely precise.
Forklift operators were guidedonly by hand and voice signals as
they couldn't even see the junctionbetween the pylon and the wing.
(32:21):
So they are working blind, right?
I mean, you gotta think they'relike way down on the ground, right?
Operating this huge forklift.
There's a mechanic working on the assemblylet's go back to the IKEA analogy.
Even that basic, you know, you have toline up the hole to get the bolt in.
(32:44):
That's a pretty key part of this,except this is an airplane engine
in a forklift being involved.
If the forklift was not positionedcorrectly, the engine pylon
assembly could rock and jam againstthe wing's attachment points.
And unfortunately that isexactly what happened during the
(33:04):
maintenance on this airplane.
The mechanics started disconnectingthe engine and pylon as a
single unit, but a shift changeoccurred halfway through the job.
Mm.
During this interval, even thoughthe forklift remained stationary, its
forks supporting the engine weight ofthe engine and pylon moved downward
(33:26):
very slightly due to a normal loss ofhydraulic pressure associated with the
forklift's engine being turned off.
Well, I tell a lot of people,not so many hands in the cookie
jar means less lost bolts.
That's so true.
It's so true.
Oh boy.
Well, Zach, this slight movement causeda misalignment between the engine
(33:50):
pylon and the wing when work resumed.
The pylon was jammed against the wingand the forklift had to be repositioned.
The resulting stress caused damage to thepylon attachment structure, damage that
was not immediately apparent and didn'tcause an immediate failure, but eventually
(34:10):
developed into fatigue, cracking this,cracking worsened with every takeoff
and landing cycle during the eightweeks that followed The aircraft flew
approximately 200 flights after this,before the attachment finally failed.
Yeah, so this is already pretty nuts,but there is actually more to this story.
(34:33):
The investigation revealed that AmericanAirlines was not alone in these practices.
Inspections of the DC 10 fleets atmultiple airlines revealed that several
aircraft also had fatigue, cracking,and damage to their pylon mounts.
Oh, this was about to happenagain and again and again.
(34:54):
Mm-hmm.
Mm-hmm.
Caused by similar maintenance procedures.
When confronted with evidence of thesemaintenance shortcuts, McDonald Douglas
stated they quote, would not encouragethis procedure due to the element of
risk end quote, and had so advisedAmerican Airlines, so they basically were
(35:15):
like, we told them they did it anyway.
Nah.
However, pass the buck.
I mean, they did.
They admitted that they, quote, didnot have the authority to either
approve or disapprove the maintenanceprocedures of their customers, end quote.
And that really is the true case.
Like once Boeing, once you know McDonald,once these guys sell the airplanes,
(35:38):
it's up to the airlines todo the maintenance on them.
I mean, I'm not gonna stop doingsomething because Toyota tells me not to.
Oh, folks, that's a true statementgosh, not OSHA approved, or
Toyota or anyone approved.
This statement highlights a fundamentalissue in aviation system safety oversight.
(36:02):
The division of responsibility betweenmanufacturers, airlines, and regulatory
agencies like the FAA, speaking of theFAA, the investigation found that they
had failed to detect and prevent the useof these improper maintenance procedures.
There were deficiencies in theirsurveillance and reporting systems
(36:25):
that should have caught theseissues before they led to disaster.
Mm-hmm.
Mm-hmm.
Beyond the maintenance issues,the NTSB also investigated why the
loss of one engine and a sectionof the leading edge had led to such
a catastrophic loss of control.
After all, the DC 10 was designed tofly safely with one engine in operative.
(36:50):
Now, you know, obviously having anentire engine removed is pretty extreme
in comparison to just one of themstopping, you know, thrust not working.
The key factor was the slatretraction on the left wing.
So unlike some other aircraft designs,the DC 10 did not have a separate
(37:13):
mechanism that would lock the extendedleading edge slats into place.
So it relied on hydraulic pressure tokeep them extended when those hydraulic
lines were severed airflow over thewing, forced the left wing slats to
retract, sucked that thing right back in.
(37:35):
Straight up Turtled.
And airflow over the wing, forced leftwing slots to retract, causing the
aerodynamic asymmetry that ultimatelyled to the stall and the roll.
I am like, I'm sofascinated by all of this,
I have so much to learn.
I feel like I need to go tolike flight school or something,
but instead I'm just going to.
(37:58):
Ignorantly tell people about things thatI am not qualified to tell them, which
is really the name of this podcast.
We're Americans.
That's what we do.
I mean, we're just ignored Americans.
It's thin.
The NTSB conducted wind tunnel andflight simulator test to understand the
aircraft's behavior over the engine.
(38:18):
Oh, after the engine detached and theleft wing slots retracted, those tests
confirmed that the damage to the wings,leading edge and retraction of the
slots had increased the stall speedof the left wing from 124 knots to 159
knots making a stall inevitable at thespeed that the aircraft was flying.
(38:41):
So nothing they could havedone, like that's, that's
what that all boils down to.
Mm-hmm.
Final critical finding here,Zach, the warning systems.
That should have alerted thepilots to the impending stall.
The DC 10 had two systems, the slotdisagreement, warning light, which
(39:06):
should have illuminated after theun uncom commanded retraction of
the S slaps and the stick shaker onthe captain's control column, which
activates close to the stall speed.
So that should have given a littleshake, the the control column.
And then obviously this lightshould have illuminated.
However, these were both poweredby the electric generator, which,
(39:29):
Separated was not generatingSo after months of meticulous
investigation, the NTSB released itsfinal report on December 21st, 1979.
The verdict was clear.
The crash had been caused bychain of events stemming from
improper maintenance procedures.
The immediate cause was the in-flightseparation of the engine and the
(39:52):
pilon assembly, but the root causeextended to design vulnerabilities,
maintenance shortcuts, andregulatory oversight failures.
Okay, let's talk about what,what they did about this.
I mean, this is the biggestcrash in US history.
So something better happened, right?
(40:15):
You think?
Yeah.
On June 6th, 1979, this isonly two weeks after the crash.
The FAA took the unprecedentedstep of grounding the entire DC
10 fleet in the United States.
It also banned foreignDC tens from US airspace.
(40:36):
So DC 10 is not in theair in the United States.
This was a dramatic move that strandedthousands of passengers worldwide and
cost airlines millions of dollars.
That is 1979 millions of dollars.
(40:56):
The grounding order was a severe blow,obviously, to McDonald Douglas, which
had marketed the DC 10 as one of the mostadvanced and safest aircraft in the sky.
But the dramatic photos of Flight 1 91with its engine missing captured moments
before the crash were published innewspapers worldwide and really became
(41:20):
an iconic image of aviation disaster.
The DC ten's reputation alreadydamaged by the earlier cargo door
incidents took a massive hit.
The aircraft wasnicknamed Death Cruiser 10
and clever.
(41:41):
It's so bad.
So bad.
Oh, man.
Yeah.
So instead of DC Death Cruiser, mm-hmm.
Wild.
And passenger confidence plummeted.
Several airlines reported the passengerswere specifically requesting to not fly
on DC tens when they were booking flights.
(42:05):
Y So they were groundeduntil July 13th, 1979.
So that's five weeks.
In which case, they also found12 others that were damaged.
No.
The FAA ultimately was satisfied that theissue was primarily related to maintenance
procedures rather than an inherentdesign flaw with the airplane itself.
(42:29):
However, the Yeah.
But you said they found others with the
stress fractures, yes.
So they, they looked at the DCtens, but they had to make sure
that it wasn't like an all DC tens.
Mm-hmm.
You know, this is a problem with theaircraft itself, and it wasn't the DC 10.
In theory was very safe.
It was the way that they were beingmaintained that was problematic.
(42:51):
However, the aircraft's type certificatewas amended to state explicitly removal
of the engine and pylon as a unitwill immediately render the aircraft.
OnAir unairworthy.
Wow.
Boom, boom.
That's like when you buy a mattressand it says, don't rip off the tag.
Do not rip off this attack,except this is an airplane.
(43:14):
I rip off that tag every time.
Subject to prosecution.
Subject to prosecution.
Okay, let's talk about whathappened to American Airlines.
Pit Bull.
He loves being a part of this podcast.
He's really a, a key figure.
The people love him.
P Bull problems.
Okay.
American Airlines was fined a measly$500,000 by the US government for
(43:39):
improper maintenance procedures, whichin my opinion is just like, what?
What on Earth?
It's literally a little slap on the hand.
I'll slap you down to thisslap that was naughty.
So $500,000.
I'm not gonna make you play this game,Zach, in 1979, money is equivalent to
(44:00):
around $2 million in today's money, whichstill in my opinion, is just like you
picture the money that they're making.
Fucking kidding me, kidding me.
These companies make $2 million a day.
They make much dollars.
So for me, that just isnot significant at all.
The human toll within the maintenanceorganization was also very severe.
(44:22):
Earl Russell Marshall, a crew chiefat Americans Tulsa Maintenance
facility who had been involved inthe maintenance procedure on that
particular plane, died by suicide thenight before he was scheduled to be
deposed by McDonald Douglas attorneys.
So that is, I mean,that's really horrible.
(44:44):
And you know, whatever his, hisinvolvement with this was obviously
you know, it's, it's another lifethat was taken by this crash.
The crash led to significantdesign and procedural changes
in the aviation industry.
In response to the accident, slat reliefvalves were mandated to prevent retraction
(45:06):
in case of hydraulic line damage.
Sounds logical.
You don't want things retracting whenthey shouldn't be retracting true.
That.
I mean, it's as simple as that.
You don't need to be a, you know,airline mechanic to figure that one out.
The FAA also required that stickshakers be in installed for both
pilots, not just the captain.
Mm-hmm.
(45:26):
The stick shaker.
I shake my stick with you.
I stick my stick shake.
Shake my stick.
All righty.
Airlines worldwide revised theirmaintenance procedures, abandoning
the practice of removing theengines and pylons as a single unit.
McDonald Douglas issued servicebulletins to improve the pylon
(45:47):
attachment design and provided detailedguidelines for proper maintenance
procedures for the victim's families.
The path to closure was long andpainful for 32 years, the victims had
no permanent memorial at the crash site.
But finally, in 2011, a memorialwas dedicated through the
(46:11):
efforts of a sixth grade class.
From a school in Chicago, the memorial,a two foot high concave wall with
interlocking bricks, displaying thenames of the crash victims is located
on the south shore of Lake O Peka,about two miles east of the crash site.
(46:34):
And Zach and I obviously will go andvisit this memorial and, and pay homage
to the victims of this terrible incident.
You didn't even know that was onthe itinerary, but it's happening.
I just hate that there's somuch of an itinerary already.
I agreed to this trip today.
I had the itinerary written months ago.
Despite the immediate impact on itsreputation, the DC 10 eventually recovered
(46:59):
and continued to serve passenger airlinesfor over three decades after the crash.
Production ended in 1988, but many DCtens were later converted to cargo use.
The last passenger DC 10 flight wasoperated by Biman Bangladesh Airlines,
in February 2nd, 2014, marking the end ofan era that spanned more than 40 years.
(47:25):
The crash of Flight 1 91 changed how theaviation industry approaches maintenance
procedures and regulatory oversight.
It highlighted the need for bettercommunication between the manufacturers,
the airlines, and the regulatory agencies.
That is so important and so critical.
If there is something that theairlines should not be doing to
(47:47):
maintain an airplane, they haveto know what they shouldn't do.
They have to know.
They have to know.
Yeah, it's just wild.
It led to improved warning systems andredundancies in critical flight control
systems as well, and it underscored theimportance of considering the potential
consequences of maintenance shortcuts.
(48:08):
No matter how time or cost effectiveit might seem for the airline,
you cannot be cut in them corners.
This disaster also changed howwe think about aircraft design.
Modern airliners now incorporate waymore fail safe systems and redundancies
to prevent a single failure fromleading to catastrophic consequences.
(48:30):
This was obviously the worstairline disaster as far as
fatalities go in the United States.
And it changed a lot of stuff.
It had some pretty importantrippling lessons learned.
Okay, Zach, that is our story for today.
Any thoughts?
Well,
(48:53):
damn.
I know Sounds fucking heavy, huh?
And very technical.
I like the technical side of things,but that's probably just 'cause
I am mechan or whatever you are.
But I'm glad that you could geekout on this one and hopefully some
of our listeners also geeked out.
Hopefully I did an okay job ofexplaining the, the do hinges that
(49:15):
connect to the other do hinges.
Well people, if you enjoyed thisepisode, please rate, review, subscribe
wherever you get your podcasts.
We are on Instagram, we are on Facebook.
We have a discussion group and wewould love to hear your thoughts.
So comments, message us,email us, do your thing.
Someone talk to us, somebody.
(49:38):
Is anybody out there?
And please join us next timewhen we will be exploring another
transportation disaster story.
Until then, remember to stow your traytables, fasten your seat belts, and
prepare for the unexpected, because notevery trip reaches its final destination.
(50:02):
Good.
Uh,
Good one, Zach.
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