Original subtitles

Above the remote Alaskan wilderness…

two planes collide.

Mayday. Mayday.

A witness races to help.

All I saw was a whole bunch of people floating.

Six people are dead.

A mid-air collision is probably the most scary thing that could happen to you.

NTSB investigators talk to the surviving pilot.

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

When they examine the on-board alerting system…

Why didn't he turn away?

the mystery deepens.

We're missing something.

But then investigators get an unexpected glimpse,

-Whoa. -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.

Mayday! Mayday!

[warnings blaring]

PULL UP!

[indistinct radio chatter]

It's a busy day at Alaska's Misty Fjords floatplane base.

Four cruise ship passengers have booked a sightseeing

flight over Alaska's spectacular southeast coast.

Okay, folks, get comfortable and fasten your seat belts.

46-year-old Randy Sullivan is the owner of Mountain Air Services and its only pilot.

Hey, looks like you're going to have the best view in Alaska.

I can hardly wait.

This will be Sullivan's second flight of the day.

Just got a few things to do before we get started.

Randy Sullivan has spent most of his career flying over Misty Fjords.

Transponder on and broadcasting. Okay, guys, put your headsets on.

Mountain Air was a small operator doing primarily sightseeing trips.

Can you guys hear me okay?

Okay, here we go.

This would have been his entire life running this company,

and he would have loved what he was doing.

All right. Flight controls free and correct.

Master fuel, check. Landing lights, check.

Just after 12 noon, the Mountain Air floatplane is ready for takeoff.

Okay, that's five minutes since last departure.

Pilots space out their takeoffs since there's no air traffic control in this area.

Misty traffic, this is Beaver 52 Delta Bravo.

Ready for a straight out. Any conflicting? Misty traffic.

Sullivan radios other pilots in the area.

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.

It's 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.

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.

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.

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.

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.

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.

Misty traffic, Beaver 2 Delta Bravo exiting Rudyerd,

climbing through 1,900 westbound.

Check that. 45 Mike Mike is just off the water now and well behind you.

It's May, and this part of Alaska is enjoying exceptionally good weather.

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.

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.

Beaver 8 Golf Mike is 2,700 feet 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 you visual.

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

I got you above and ahead of me, Randy. Enjoy the ride.

Oh, uh huh, uh

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, before you get too close.

Coming up in about two minutes on your right,

you're going to see one of the highlights of the trip, the majestic Mahoney Falls.

20 minutes into the flight, the Beaver approaches the waterfall.

Passengers are treated to a spectacular view.

The Beaver and another aircraft collide.

The Beaver basically came apart. It free-fell 3,000 feet from the sky.

A retired fisherman on George Inlet is shocked by what he sees.

Mayday. Mayday. This is Hotel Sea calling Coast Guard radio.

Go ahead, state the nature of your emergency.

The second plane involved is a larger ten passenger de Havilland Otter.

Two float planes down, George Inlet.

The Otter was still largely intact. There was damage.

The pilot obviously kept his cool and managed to control the aircraft.

I saw a, an Otter floatplane crash into the water with a huge splash and,

I got closer and all I saw was a whole bunch of people

floating in the, in an area 50, 60 yards.

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

The ten 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 destinations on Earth,

collide in mid-air?

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, 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.

Aaron Sauer is named lead investigator.

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.

There was a lot of debris that was mixed into the terrain in 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.

The other aircraft, the Otter, is owned by the largest tour operator in the area,

Taquan Air. It sank in 80 feet of water.

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.

Um, tag the Beaver wreckage, and when the Otter comes, we're going to put it there.

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 will help us piece this together.

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.

As the team surveys the Beaver wreckage,

they find evidence that can help them piece together the violent collision.

These are sawtooth marks, from a propeller striking the right wing.

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.

The discovery begins to unveil what happened in the skies over Misty Fjord.

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 their cruise ship in Ketchikan.

The Beaver left first,

and a few minutes later, the Otter departed.

With a basic understanding of how the two planes collided,

investigators try to pinpoint where the accident occurred.

We had one witness…

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 sky.

Based on his account the collision happened, somewhere in here.

Investigators now know exactly where the accident occurred,

but they still don't know why.

Maybe, they were converging on this point.

The planes collided very near the scenic Mahoney Falls.

It is certainly possible.

It has happened before.

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.

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.

Did Alaska's rapidly changing weather play a role in the accident?

So 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 camera, eight miles from the accident.

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. -Mmhm

The weather conditions in Ketchikan on the day of the accident were beautiful.

So at that point, we knew that the conditions

were not going to be a factor in this accident.

Something else prevented these guys from seeing each other.

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.

What prevented the pilots from seeing each

other as they converged on the scenic waterfall?

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 a

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.

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 call-outs, 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 on board an ADS-B traffic warning system.

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 going to have your attention immediately.

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

It looks like the Otter had an alerting system installed on board.

What about the Beaver?

Yeah, it had a system installed on it as well.

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.

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 color screen inside the cockpit plots other nearby aircraft on a moving map.

What does the Beaver have?

Well, the Beaver pilot had a different system.

It had a tablet to display traffic info.

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?

Let's see what we got.

Investigators review whether ground stations

received any GPS transmissions from the aircraft,

detailing their locations.

There's the Beaver.

Misty traffic. Beaver 2 Delta Bravo exiting Rudyerd.

Climbing through 1,900 westbound.

And there's the Otter.

All right, folks, if you look outside your windows down at the hills below,

you might just see some wildlife.

Both airplanes were broadcasting their position, but they still hit each other.

Doesn't make sense.

Maybe the system didn't issue an alert.

The Otter pilot would know.

Seems like so many of these investigations

when you have a mid-air 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.

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, 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.

Got one three miles out.

Three 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-

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

Hang on, everyone.

Was there any alert from the traffic system?

Nothing.

After the impact, I just went into survival mode.

Brace for impact!

Brace, brace, brace!

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.

Investigators are now confident the collision happened without a warning

to alert the Otter pilot.

The question is, why?

Hang on, everyone!

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

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.

It's painting targets.

There's the Beaver approaching.

The alert should happen any second now.

As the Beaver gets within two and a half miles, an alert should sound.

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

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 defense 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-

The NTSB must now figure out why a critical piece of safety equipment failed.

Traffic alerting system, was installed…

in 1999.

One of the first in the country.

They take a closer look at the de Havilland Otter's traffic alerting system.

Looks like the 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 Ranger 978.

Yes, and take a look at what wasn't included in the upgrade.

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.

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.

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 center is the Beaver.

The Otter is at three miles out now.

There is no alert, warning of the approaching Otter.

We're missing something.

Determining why neither of the traffic alerting systems in, 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.

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.

It's turned off.

A key component was not operating at the time of the crash.

That is odd.

There was a critical piece of equipment on board the Otter called the GSL 71.

The GSL 71 is a control panel for the alerting system.

It broadcasts the plane's altitude to aircraft and ground stations.

Let's see exactly how these components work.

Investigators examine the role of each component of the Otter's traffic systems

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

Well this is not a simple setup.

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.

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.

Was that airplane above them? Below them? Same altitude? Unsure.

When was the last time the Otter, transmitted altitude data?

Investigators review when the Taquan Air Otter

last broadcast its altitude to ground stations.

April 29th.

The last inspection and maintenance was on, April 30th.

The day after its last broadcast.

The team considers whether the GSL 71 was turned off for maintenance

two weeks before the crash, and never turned on again.

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.

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.

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.

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 pre-flight checklist?

No. It, wasn't a piece of equipment that I ever touched or concerned myself with.

They review the company's pre-flight 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 pre-flight checklist.

Okay.

Thank you.

Investigators determine the Otter pilot

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

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.

What did you learn from the Otter pilot?

He didn't know the unit was turned off.

It wasn't on his pre-flight 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.

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 defense, 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 pilot's field of view.

NTSB investigators consider exactly what the pilots could see

from the cockpits of their airplanes.

So the Beaver pilot would have 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?

I don't think so.

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

There's no way he could have seen,

the Otter approaching from behind and to the right.

The Beaver has issues with visibility because

of the structural design of the airplane.

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

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.

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 two o'clock.

Eh, 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?

Using a 3D scan of an Otter cockpit, the team recreates the pilot's view out of

the left windshield in the moments before the collision.

This is just minutes before the collision.

The Beaver is still three miles away,

roughly in this area of the windscreen.

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.

When two objects are converging,

there is little relative motion in a pilot's

visual field to attract a pilot's attention.

Okay.

We've got one three miles out, three o'clock.

Opposite direction.

No conflict.

The Beaver's an eighth mile away.

Still don't see it.

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.

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 going to pass our famous Mahon-

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.

But they can't be completely certain.

It's hard to know for sure.

His perspective is going to change

depending on where his seat is set

and where his head is.

Investigators need more information.

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.

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's mostly hidden.

Except for here.

It's hard to be 100% certain without, knowing the pilot's exact seat position.

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

Maybe there's something on them.

We'll check on that.

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.

After several weeks of painstaking work,

investigators review images taken by the Otter passengers.

No, there's nothing here.

There are no pictures taken near the time of the collision.

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

Whoa.

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.

The photo of the approaching Otter was taken seconds before impact.

It was a moving experience.

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

Um, zoom in.

But can it answer the question of whether the Otter pilot could see the Beaver?

I can see into the Otter cockpit.

It's the break the investigators needed.

Uh, try to zoom in a little bit more.

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.

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.

It's 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.

Investigators now understand why the Mountain Air Beaver

and the Taquan Air Otter collided.

Okay, folks, in a few seconds, we're going to pass our famous Mahon-

Neither pilot could see nor be alerted to

how close their aircraft were to each other.

Hang on, everyone!

Brace for impact!

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 darn busy,

he needs all the help he can get.

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.

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.

The NTSB recommends regulations requiring mandatory air traffic alerting

for air tour operators in high traffic areas.

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 number of collisions that take place.

UNOFFICIAL SUBS BY STER