All language subtitles for M.2003-S24E05-Without.Warning.WEBDL-1080pEAC3.5.1h264-NOGRP_track3_[eng]

(narrator): Above the remote
Alaskan wilderness...

(impact)

(screaming)

two planes collide.

- Mayday. Mayday.

(narrator): A witness
races to help.

- All I saw was a whole bunch
of people floating.

(narrator): Six people are dead.

- A mid-air collision is
probably the most scary thing

that can happen to you.

(narrator): NTSB investigators
talk to the surviving pilot.

- Look, he was just there.
I couldn't avoid him.

(narrator): When they examine
the onboard alerting system...

(Bramble): Why didn't he
turn away?

(narrator): ...the mystery
deepens.

- We're missing something.

(narrator): But then,
investigators get
an unexpected glimpse...

- Whoa.
(narrator): ...into
a key moment in time.

- It was eerie and disturbing
to see the photos

because they were taken in
a person's last moments.

(theme song)

(soft piano music)

(narrator): It is a busy day

at Alaska's Misty Fjords
float plane base.

Four cruise ship passengers
have booked a sightseeing flight

over Alaska's spectacular
southeast coast.

- Okay, folks, get comfortable
and fasten your seatbelts.

(narrator): 46-year-old
Randy Sullivan is the owner

of Mountain Air Services,
and is its only pilot.

- Hey. It looks like you're
gonna have the best view
in Alaska.

- I can hardly wait.
(chuckling)

(narrator): This will be
Sullivan's second flight
of the day.

- I've just got a few things
to do before we get started.

(narrator): Randy Sullivan has
spent most of his career

flying over Misty Fjords.

(bright music)

- Transponder on
and broadcasting.

Okay, guys,
put your headsets on.

(Floyd): Mountain Air was

a small operator doing primarily
sightseeing trips.

- Can you guys hear me okay?

Okay, here we go.

(Floyd): This would have been
his entire life

running this company
and he would have loved

what he was doing.

- Alright.

Flight controls,
free and correct.

Master fuel, check.

Landing lights, check.

(narrator): Just after 12 noon,

the Mountain Air floatplane
is ready for takeoff.

- Okay, that's five minutes
since the last departure.

(camera shutter clicks)

(narrator): Pilots space out
their takeoffs

since there's no air traffic
control in this area.

(Sullivan): Misty traffic,

this is Beaver 5-2 Delta Bravo
ready for a straight-out.

Any conflicting? Misty Traffic.

(narrator): Sullivan radios
other pilots in the area.

(Floyd): In airspace like
the Misty Fjords,

the pilots all control
themselves.

And it's primarily
a see-and-be-seen situation.

Without any air traffic control
to keep you separated,

you have to maintain
that separation yourself.

(narrator): It is a textbook
takeoff in light winds.

Today's 40-mile flight will
take passengers

from Rudyerd Bay to Ketchikan.

They'll cross high mountains
and dramatic terrain.

- The Misty Fjords is an
absolutely beautiful area.

It's towering mountains,
glaciers,

lakes, fjords, wildlife.

And the best way to see
a place like that, of course,

is from an airplane where
you can get the full impact
of the scenery

and the immenseness of the area.

(soft music)

(narrator): Every year,
more than 100,000 cruise ship
passengers

visit Alaska's Misty Fjords.

The flight tours have become
an essential experience

for those who can afford
the luxury price tag.

- If you look out to your left,
you'll see cliffs

that were carved smooth
by the last great ice age.

(narrator): Randy Sullivan
points out the highlights
throughout the flight.

- Being a single pilot operation
while you're doing the tours,

you're multitasking with
your customers all the time

trying to give them the best
tour that you can give them.

At the same time, you're also
multitasking as a pilot

where you're trying to maintain

your situational awareness
of all the other aircraft.

As well as you're a lot of
times flying at very low level

through the terrain which adds
one more bit of complexity

to the entire operation.

(narrator): Mountain Air
Services operates

a De Havilland Beaver,
a single-engine prop plane.

The Beaver was originally built

for the United States Air Force
in 1951

but many are now operated
by northern bush pilots.

(Floyd): The De Havilland Beaver
was a uniquely designed
airplane.

And the takeoff and landing
is absolutely incredible.

That's what makes it
so versatile in the bush is that

you can get it in and out of
pretty much any little lake.

Uh, if you're on wheels or skis,

you can get it off short strips
or short frozen lakes.

(plane buzzes)

- Misty traffic, Beaver 2
Delta Bravo

exiting Rudyerd, climbing
through 1,900 westbound.

(radio): Check that.

45 Mike Mike is just off
the water now

and well behind you.

(narrator): It's May
and this part of Alaska

is enjoying exceptionally
good weather.

(Floyd): On the Alaska coast,
the weather can change
extremely rapidly.

It can go from a beautiful
clear day

to just horrible weather within
a very short period of time.

When the days are good,

all the aircraft are flying,

everybody is out making hay
while the sun shines.

- Have a good cruise so far?
- It's been great.

(narrator): The forecast for
tomorrow is low clouds and rain.

So today, Sullivan plans to
operate a full day of flights.

- You all are pretty lucky.

They call this place
the Misty Fjord for a reason.

Weather like this
is pretty rare.

(radio): Beaver 8 Golf Mike,

is 2,700 ft in the climb
exiting the Bay.

We've got the Mountain
Air Beaver ahead.

We will fall in trail behind.

- Hey, Dave.
I've got you on display,

but I don't have your visual.

As long as you can see me,
we're good.

(radio): I got you above
and ahead of me, Randy.

Enjoy the ride.

- Oh.
(chuckles)

Even if we can't see each other,

the display lets us know
where the other planes are.

- Cool.

- The traffic systems
will enhance your ability

for the see-and-avoid because
it will alert you of aircraft

that you may have missed because
of visibility issues

or you get too close.

(Sullivan): Coming up in about
two minutes on your right,

you're gonna see one of
the highlights of the trip:

the majestic Mahoney Falls.

(bright music)

(narrator): 20 minutes
into the flight,

the Beaver approaches
the waterfall.

Passengers are treated
to a spectacular view.

(impact)

The Beaver and another aircraft
collide.

- The Beaver basically
came apart.

It free-fell 3,000 ft
from the sky.

(dramatic music)

(narrator): A retired fisherman
on George Inlet

is shocked by what he sees.

- Mayday. Mayday,

this is "Hotel C"
calling coast guard radio.

(coast guard): Go ahead.

State the nature
of your emergency.

(sombre music)

(narrator): The second plane
involved is a larger,

10-passenger De Havilland Otter.

- Two float planes down,
George Inlet.

(Floyd): The Otter was
still largely intact.

There was damage.

The pilot obviously
kept his cool

and managed to control
the aircraft.

- I saw an Otter float plane

crash into the water
with a huge splash.

And I got closer and all I saw

was a whole bunch of people
floating in a...

in an area, um, 50-60 yards.

But there was one person, never
made it out of the airplane.

(narrator): The 10 survivors,
including the pilot,

are rushed to hospital.

There are no survivors
from the plane piloted
by Randy Sullivan.

How could two planes in
one of the most popular tourist
locations on Earth

collide in mid-air?

(soft music)

Within hours, the National
Transportation Safety Board,

or NTSB, dispatches a team
of investigators

to search for wreckage.

- We still have to recover
the planes, and then we have

to look at those and it takes
some significant work

to really understand how
the two came together,

but we have some great experts
at the NTSB who are well versed
in that.

(narrator): Aaron Sauer is named
Lead Investigator.

(Sauer): The wreckage area
of the Beaver

was scattered for
about 3,000 feet.

Uh, a portion of the main
fuselage was located

upside down in the saltwater.

But there was a lot of debris

that was mixed into
the terrain,

and that mountainous area.

Vegetation was high.

It was very difficult
to navigate to try and recover

as much of the debris from
the Beaver that we could.

(narrator): The other aircraft,
the Otter,

is owned by the largest
tour operator in the area,
Taquan Air.

It sank in 80 ft of water.

(Sauer): The floats of
the Otter were separated.

They ended up washing ashore.

But ultimately, they were able
to get divers down,

locate the wreckage
almost immediately.

And they were able
to successfully get

that aircraft up on that barge.

(sighs)
- Um, Tag the Beaver wreckage,

and when the Otter comes,
we can put it there.

(narrator): The small
sightseeing planes

were not required
to carry black boxes.

- Keep an eye out for avionics,
cameras, phones,

anything with photos or data

that'll help us piece this
together.

(narrator): Without recorders,
the investigation becomes
much more difficult.

- So without the cockpit
voice recorder

and flight data recorder,

we had to look for
other sources of data.

- Hey, help me move this.

(narrator): As the team surveys
the Beaver wreckage,

they find evidence that can help
them piece together

the violent collision.

(Bramble): These are
saw-tooth marks

from a propeller
striking the right wing.

(Sauer): We wanted to understand
what angle did we have?

That was very important
for us to understand

in order to recreate
the collision

and aid us in
the investigation.

- The pattern's in
the inboard direction.

- So the Otter came from behind,
and to the right.

(narrator): The discovery
begins to unveil

what happened in the skies
over Misty Fjord.

(Sauer): The collision angle
was important for us

because what it told us is

both airplanes weren't
necessarily on a head-on
collision course.

They were more or less headed

to the same location with
a shallow degree of angle.

The collision was more
of a sideswipe.

Both planes took off
from Rudyerd Bay here...

and headed to the cruise ship
in Ketchikan.

- The Beaver left first.

A few minutes later,
the Otter departed.

(narrator): With a basic
understanding of how

the two planes collided,

investigators try to pinpoint
where the accident occurred.

- We had one witness...

(soft investigative music)

...who was located here.

- We had a witness that
was hunting in the area,

that didn't see the collision,
but heard the collision,

which then, in turn, gave us
an idea of where exactly

did this happen up
in a point in the sky.

- Based on his account,
the collision happened

somewhere in here.

(narrator): Investigators now
know exactly

where the accident occurred,
but they still don't know why.

- Maybe they were converging

on this point.

(narrator): The planes collided

very near the scenic
Mahoney Falls.

- It is certainly possible.

It has happened before.

(narrator): A similar mid-air
collision happened over
Arizona in 1986.

A Twin Otter and a helicopter

collided over the Grand Canyon,
killing 25 people.

Both aircraft were also
approaching a popular
scenic attraction.

(Bramble): Air tour flights
have a higher rate

of mid-air collisions
statistically speaking because

they operate in areas with

dense traffic around
various scenic landmarks.

And in addition, they operate

without air traffic control
separation.

What was the weather like
that day?

- I'll check it out.

(narrator): Did Alaska's rapidly
changing weather

play a role in the accident?

- The weather conditions
in any accident are important

to understand the environment

that these pilots
are operating in.

Are the weather conditions
cloudy? Does that limit
their ability to see?

Does it limit their ability to
react to certain situations?

These are from a weather cam,
8 miles from the accident.

(narrator): Investigators review
weather reports

for nearby George Inlet
at the time of the accident.

- A few scattered clouds...

but much higher than
they were flying.

- Mm-hmm.

(Sauer): The weather conditions
in Ketchikan

on the day of the accident
were beautiful,

so at that point, we knew that
the conditions

were not gonna be a factor
in this accident.

- Something else prevented these
guys from seeing each other.

(soft piano music)

What if...

the pilots didn't have
enough time

to look out the window
for other traffic?

- Or maybe the pilots
were trying to give

their customers the best view.

(narrator): What prevented
the pilots from
seeing each other

as they converged on
the scenic waterfall?

(Floyd): Flying an aircraft
full of tourists

can be a very challenging task.

You have a number of people
that all want to ask questions,

they all want to see
different things,

especially in an area
like the Misty Fjords

where there is so much to see.

- It is a lot for a pilot
to do all at the same time.

- Well, the local pilots
certainly were concerned.

Enough to create this.

(narrator): Investigators
discover a set of guidelines

agreed upon by tour operators

to enhance safety
over Misty Fjords.

- The Letter of Agreement
between the operators

was intended to help them
coordinate their routes
of flight

and their callouts so that
they could become better aware

of where they would each be
operating and avoid each other.

The companies were aware of

this hazard of mid-air
collisions

and that they were
attempting to implement

some procedural mitigations
against this hazard.

- It looks like most
aircraft flying tours

also had onboard an ADS-B
traffic warning system.

(narrator): ADS-B, or Automatic
Dependent Surveillance
Broadcast,

is a traffic alerting system

that transmits a plane's
GPS location and altitude

to ground stations
and other aircraft.

If two airplanes get too close
to each other,

an alert is issued
in both cockpits.

- When your traffic
system tells you

you've got a conflict,

it's gonna have your attention
immediately.

It will only tell you that
there's a problem when there is.

- Hmm.
- It looks like the Otter

had an alerting system
installed onboard.

What about the Beaver?

- Yup, it had a system
installed on it as well.

(Sauer): It was important for us
to understand

which aircraft had
which equipment

as far as alerting capability,
traffic displays.

Okay, here's
the Otter's system.

(narrator): Investigators first
examine the Otter,

the aircraft that collided with
the smaller plane to its left.

The Otter uses GPS
and a radio transponder

to broadcast
its altitude and position.

A colour screen
inside the cockpit

plots other nearby aircraft
on a moving map.

- What did the Beaver have?

- Well, the Beaver pilot
had a different system.

It had a tablet
to display traffic info.

(Sauer): So we knew that
both aircraft were equipped with

some level of traffic display,

so the question was, were they
able to function as designed?

(birds chirping)

(Bramble): Ah.

- Let's see what we got.

(narrator): Investigators review
whether ground stations

received any GPS transmissions
from the aircraft

detailing their locations.

(Bramble): There's the Beaver.

- Misty traffic,
Beaver 2 Delta Bravo

exiting Rudyerd climbing
through 1,900 westbound.

(Sauer): And there's the Otter.

- Alright, folks, if you look
outside your windows

down at the hills below, you
might just see some wildlife.

(suspenseful music)

- Both airplanes were
broadcasting their position

but they still hit each other.
- It doesn't make sense.

- Maybe the system
didn't issue an alert?

- The Otter pilot would know.

(Banning): It seems like so
many of these investigations

when you have a mid-air are...

are just not survivable.

And so, it was...

it was very fortunate to be able
to talk to the pilot.

- Tell me about the flight.

(narrator): Investigators
interview the Otter pilot,

Lou Beck, who has just been
released from hospital.

- Passengers were happy.
Air was smooth.

- Was it busy out there?

- Visually, I never saw
anyone else.

- What about the traffic
alerting system?

- It was on. I saw targets
on the screen, but...

they were well south of me.

Okay.

I've got one 3 miles out,
3 o'clock.

Opposite direction, no conflict.

I flew a longer route
than the other planes.

Took me away from most
of the regular traffic.

- But you still ended up
at the waterfall?
- I did.

That's when all hell
broke loose.

Okay, folks, in a few seconds,

we're going to arrive
at the beautiful--

(impact)

He was just there.
I couldn't avoid him.

Hang on, everyone!

(plane rattles violently)

(passengers screaming)

- Was there any alert from
the traffic system?

- Nothing. After the impact,
I just went into survival mode.

Brace for impact!

Brace, brace, brace!

(plane buzzing)

(crash)

(soft music)

(Bramble): The pilot seemed
very attentive

to mid-air collisions
as a hazard.

He was aware of the cockpit
display of traffic information
in the cockpit.

And he recalled looking at it

to scan for traffic
before the collision.

- Look, I just want to
reiterate that the alert system

did not sound an alert.

- Thank you.

This was very helpful.

(narrator): Investigators
are now confident

the collision happened
without a warning

to alert the Otter pilot.

The question is why?

(Otter pilot): Hang on,
everyone!

- Let's have a look at
the Otter's traffic
alerting system.

(narrator): Investigators use
the ground station data

to recreate what the Otter pilot
would have seen

on his traffic alerting system

moments before crashing
into the Beaver.

(Sauer): It's painting targets.

There's the Beaver approaching.

- The alert should happen
any second now.

(narrator): As the Beaver
gets within 2.5 miles,

an alert should sound.

- It's not doing anything.
There's no alert.

(curious music)

- It was very surprising to us
that the cockpit display

of traffic in the Otter
didn't provide traffic alerts

because that's a really
important defence against
mid-air collisions.

- There is something not right
with the alerting function.

- Okay, folks, in a few seconds,

we're going to arrive
at the beautiful--

(impact)

(screaming)

(narrator): The NTSB must now
figure out

why a critical piece of
safety equipment failed.

(crash)

- The traffic alerting system
was installed...

in 1999.

One of the first in the country.

(narrator): They take
a closer look

at the De Havilland Otter's
traffic alerting system.

- It looks like FAA paid for it

as part of an experimental
program.

- The Capstone Project that
the FAA sponsored

was a program to reduce mid-air
collision accidents in Alaska.

In 2015, the Otter got
an upgrade from the FAA.

- What kind of upgrade?

- Take a look.

- They swapped out a Garmin
transceiver for a RANGR 978.

- Yes.

And take a look at what wasn't

included in the upgrade.

(narrator): When the traffic
system was upgraded
on the Otter,

its alerting function
was removed.

- The FAA considered the traffic
alerting audio capability

to be classified as immature

and no longer part of
the upgraded system.

That was a head scratcher
for our team.

(narrator): But even if
the Otter pilot

didn't receive an alert,

the Beaver pilot should have
received one on his system.

In this part of the world,

alerting systems are neither
mandated nor regulated.

Planes can have different
systems or none at all.

- The Beaver pilot had been
utilizing an iPad

that was using an application
for navigating and understanding

where traffic would be
in his surrounding area.

- The pilot paid
for his own system.

- And so, he would have had
a fully functional system,

including alerting capabilities.

- According to this, yes.

- I think it's clear the Beaver
pilot was concerned
about safety.

He had gone at his own expense
and installed ADS-B equipment

in his airplane that was not
required per regulation.

(narrator): Did the Beaver's
system also fail

to alert the pilot?

Investigators use
the ground station data

to recreate what the Beaver
pilot would have seen and heard

in the cockpit
leading up to the crash.

- The centre is the Beaver.

The Otter is at 3 miles out now.

(narrator): There is
no alert warning of
the approaching Otter.

- We're missing something.

Determining why neither of
the traffic alerting systems

in the airplanes
warned the pilots

about the impending collision
was something that

we had to sort out in order
to figure out

why the collision happened.

- Is that everything?

Thank you.

(narrator): With the Beaver's
ADS-B system

destroyed in the crash,

the NTSB turns to the only
evidence that remains:

salvaged parts of the Otter's
traffic alerting system.

- Hey, check this out.

(mysterious music)

- It's turned off.

(narrator): A key component was
not operating

at the time of the crash.

- That is odd.

- There was a critical piece
of equipment onboard the Otter

called the GSL 71.

(narrator): The GSL 71 is
a control panel

for the alerting system.

It broadcasts the plane's
altitude

to aircraft and ground stations.

(Sauer): Let's see exactly
how these components work.

(narrator): Investigators
examine the role

of each component of
the Otter's traffic systems,

to consider the consequences of
having the GSL 71 turned off.

(sombre music)

- Well, this is not
a simple set up.

- So, a surprising thing about
the system on the Otter was that

it was a mixture of
new and old parts.

Look at this.

- If the GSL 71 is off,

altitude information will not

be broadcast to other aircraft.

- If the Otter wasn't
broadcasting,

then the Beaver would not
have gotten an alert.

(narrator): Investigators get
their biggest lead yet.

- Because the GSL 71 was off,

other aircraft had no idea

what altitude the Otter
was currently operating at.

(impact)

Was that airplane above 'em,

below 'em, same altitude?

Unsure.

(dramatic music)

When was the last time the Otter

transmitted altitude data?

(soft investigative music)

(narrator): Investigators review

when the Taquan Air Otter

last broadcast its altitude
to ground stations.

- April 29th.

- Um...

The last inspection
and maintenance was uh...

April 30th.

- The day after
its last broadcast.

(narrator): The team considers

whether the GSL 71
was turned off for maintenance

two weeks before the crash

and never turned on again.

(Sauer): We spoke to
maintenance personnel,

but during the course
of interviews,

we never really were able
to completely understand

why the unit was
in the off position.

(narrator): Since the Otter
wasn't broadcasting
its altitude,

the Beaver never received
an alert.

Why didn't the Otter pilot
check if he was broadcasting
his altitude

on the day of the crash?

- I have some additional
questions for you.

(soft piano music)

Were you aware that
the control panel was off?

- No.

- Why not?

- I saw other aircraft
on the display screen.

So that told me
the system was working.

(narrator): Investigators
discover that the pilot

didn't fully understand how

all the components of
the traffic surveillance
system worked.

- No conflict.

- We learned that there had been
other pilots in the airplane

preceding the accident with
the accident pilot

who apparently didn't catch
that the GSL 71

was in the off position either.

I think on one of those flights,

he actually had the chief pilot
of the company with him,

and the GSL 71 was still
in the off position.

And we know that because
the data wasn't streamed.

The pressure altitude
wasn't streamed.

- Did you check to see
if the GSL unit was "on"

during your preflight
checklist?

- No, it wasn't a piece of
equipment that I ever touched

or concerned myself with.

(narrator): They review
the company's

preflight checklist
with the Otter pilot

to understand why a crucial part
of the alerting system

wasn't turned on.

- Radio set.

Altimeter set.

Fuel checked.

It's not on my preflight
checklist.

(sighs)

- Okay.

Thank you.

(narrator): Investigators
determine the Otter pilot

wouldn't have checked the status
of the GSL 71.

(Bramble): In an airline
environment,

something as critical as that

would definitely be
on a checklist.

And so, the fact that it wasn't,

might lead him to think that
it wasn't super critical

or it would just not have risen
to the level of something that

he would pay attention to
each and every time.

(melancholic music)

- What did you learn
from the Otter pilot?

- He didn't know
the unit was turned off.

It wasn't on his preflight
checklist.

- You have to be so diligent
at all times

when you're flying the aircraft,
especially in a busy,
busy area like that.

As good as the traffic systems
can be, they can sometimes fail.

(narrator): The team now knows

why neither traffic system
alerted the pilots.

- It still doesn't explain why
the pilots didn't see each other

on a perfectly clear day.

See-and-avoid is the system
by which pilots are taught

to avoid one another
when air traffic control

is not providing
positive separation.

It is considered
a last line of defence

and it involves
systematically scanning

different parts of the sky
visible through the windscreen

to ensure that there aren't
any other aircraft
on a collision course.

- Okay, let's check out
the pilots' field of view.

(narrator): NTSB Investigators
consider exactly what the pilots

could see from the cockpits
of their airplanes.

- Hmm...

So, the Beaver pilot
would've been doing his scans,

looking left...

no problem.

Looking right...

hmm, there was a passenger
in the front seat

restricting his view.

- And the Otter was to the right
coming from behind.

- The passenger
sitting in your seat

might have been able to see it.

But not the pilot.

- What about looking back
through the cabin?

- Mmm...

I don't think so.

The windows are too small
and passengers are in the way.

(sighs)

There's no way he could have
seen the Otter

approaching from behind
and to the right.

(Floyd): The Beaver has issues
with visibility

because of the structural design
of the airplane.

You have door posts, and window
posts, and overhead structure,

etc., etc., that does obscure
your view.

And, of course, in the old days,

that wasn't really a huge
concern because, of course,

there was a lot less
airplanes in the sky.

- The Otter pilot might have had

a perfect view to the left
and straight ahead.

- Let's figure that out.

- So the Otter pilot said

he was lining up the waterfall
to his right.

- So this was the pilot's
field of view.

(narrator): Investigators
consider what the Otter pilot

could see at the time
of the crash.

- So let's assume that
he was looking to his right,

say about 2 o'clock.

- Ah, but the pilot was adamant

that he was still doing
his full visual scans,

left and right, up and down.

So what would he see
if he looked to his left

towards the Beaver?

(narrator): Using a 3D scan
of an Otter cockpit,

the team recreates
the pilot's view

out the left windshield
in the moments

before the collision.

- This is just minutes
before the collision.

The Beaver is still
3 miles away,

roughly in this area
of the windscreen.

(narrator): The Beaver
is little more

than a speck on the horizon.

- It's hard to pick out
the Beaver

against the dark mountains
in the distance.

(Bramble): When two objects
are converging,

there is little relative motion
in a pilot's visual field

to attract a pilot's attention.

- Okay.

Got one 3 miles out,
at 3 o'clock.

Opposite direction...

no conflict.

- The Beaver's
an eighth mile away.

- I still don't see him.

(narrator): The window post,
called an A-pillar,

obstructs the view
of the Beaver.

- Okay, we're coming up
on the moment of impact.

- The Beaver
came out of nowhere.

- I didn't see it until impact.

(narrator): The Otter's
ADS-B system doesn't have

the alerting capability
to warn of the other plane.

And the pilot's view of it
is obstructed.

- Okay, folks, in a few seconds,

we're gonna pass our famous--

(impact)

(Bramble): The animation was
fascinating because

it showed how almost perfectly

the Beaver was obscured by
the window post in the cockpit

of the Otter from the pilot's
perspective.

And it wasn't until
the last half-second or so that

it sort of blossomed from behind
the post and became a red flash.

(narrator): But they can't be
completely certain.

- It's hard to know for sure.

His perspective
is gonna change,

depending on where his seat
is set, and where his head is.

(narrator): Investigators
need more information.

(Sauer): We can change
sight lines,

we can adjust angles,

we can adjust views,

but we do not have the ability
to say that that was, in fact,

the pilot's position
at any point in time

during that flight.

(narrator): The team
performs a study

using 27 different eye positions

to evaluate how the A-pillar

would have blocked the Beaver
from the Otter pilot's view.

- The Beaver is mostly hidden.

- Except for here.

It's hard to be 100% certain

without knowing the pilot's
exact seat position.

(investigative music)

- What about the cameras that
we recovered from the wreckage?

Maybe there's something on them.

- I'll check on it.

Based on it being an air-tour
operation being in 2019,

fortunately, we were able
to locate

quite a bit of still
imagery and video.

- Okay, let's see
what we've got.

(narrator): After several weeks
of painstaking work,

investigators review images
taken by the Otter passengers.

(mysterious music)

- No. There's nothing here.

(narrator): There are
no pictures

taken near the time
of the collision.

- Let's check out the photos
taken from the Beaver.

Whoa.

(narrator): They find a photo
of the Otter

taken by a passenger
in the Beaver.

- It was eerie and disturbing

to see the photos
taken by the passengers.

Let's take a closer look.

(narrator): The photo of
the approaching Otter

was taken seconds
before impact.

(dramatic music)

(plane buzzing)

(Bramble): It was
a moving experience.

You knew it was gonna be
the last moments for
some of those people.

- Uh, zoom in.

(narrator): But can it answer
the question of whether

the Otter pilot
could see the Beaver?

- I can see into the Otter
cockpit.

(narrator): It's the break
the investigators needed.

- Uh, try to zoom in
a little bit more.

(narrator): The photo captures
the Otter's exact position.

- The A-pillar is blocking
the pilot's head.

- If we can't see the Otter
pilot's head

from this perspective,

he wouldn't have seen
the Beaver.

(narrator): Investigators
are now certain

that for almost three minutes
before the collision,

the Otter's windshield structure

blocked the pilot's view of
the approaching Beaver.

(Sauer): It was crucial for us
to understand that

at that point, the Otter pilot
had very limited chance

of avoiding that collision

due to his sight being obscured

by that aircraft structure.

(narrator): Investigators
now understand

why the Mountain Air Beaver

and the Taquan Air Otter
collided.

- Okay, folks, in a few seconds,

we're gonna pass our famous--

(impact)

(narrator): Neither pilot
could see nor be alerted

to how close their aircraft were
to each other.

(Otter pilot): Hang on,
everyone!

Brace for impact!

(crash)

(Floyd): You just can't afford

not to have a traffic system.

When it's so busy as that,
in terrain like that,

when the pilot is
so darned busy,

he needs all the help
he can get.

(narrator): The NTSB's
final report

highlights the limitation of
see-and-avoid for pilots

and recommends new rules
for preventing the downgrading

or disabling of traffic-alerting
systems.

(Bramble): This accident in
a nutshell,

to me, is about the rolling back
of safety protections

without anybody taking
a critical look at

what they were doing.

(soft piano music)

(narrator): The NTSB
recommends regulations

requiring mandatory
air traffic alerting

for air tour operators
in high-traffic areas.

(Sauer): I have worked
a number of mid-air collisions

during my career here
at the NTSB,

and this accident was
very preventable.

There are limitations,
as all of us all well know,

with the concept of
see-and-avoid,

and the technology
that exists today

should be in these aircraft
to help reduce

these numbers of collisions
that take place.

(♪♪)

Subtitling: difuze