Original subtitles

A horrific collision in the skies

above southern Germany...

...is witnessed by people on the ground.

- 71 people are dead.

We as accident investigators did not

have an idea of what exactly happened.

- It doesn't make sense.

- The radar data only deepens the mystery.

- Neither one is trying to get out of the way.

- I just gotta use the facilities.

- Descend? Really? We're going to descend?

Expedite decent.

To solve the mystery,

investigators will need to disentangle a web

of critical radio transmissions.

The controller is guiding us down.

A lot of things had to fall into place

just the wrong way for this to occur.

It really woke a lot of people up.

- Mayday, Mayday.

Pull up!

It's 11 p.m. in Switzerland,

and airports across the region are closing down for the night.

- You're off?

See you in a few hours.

- In the Skyguide Control Center in Zurich...

- Thai Inter 9-3-3, proceed to ALGOI.

Copy, proceed to ALGOI, Thai Inter 9-3-3.

...Air Traffic Controller Peter Nielsen

is working the night shift.

- Bavarian 3-0-5, descend flight level 2-2-0.

- He's been on the clock for just over three hours,

and has six more to go.

Tom Laursen is a former Skyguide controller

who worked with Peter Nielsen.

The night shift in Zurich at the time

had quite a lot of traffic,

but around 11:30-12 o'clock,

it reduced to five to seven aircrafts an hour,

and it was possible to do it alone.

- Topswiss 9-3-5, proceed direct to TORPA.

Direct to TORPA, Topswiss 9-3-5, thank you.

Nielsen manages the safe transit

of all aircraft in his airspace.

- For further instruction, contact Padua 1-2-0

decimal 7-2, bye-bye.

- Air traffic control is one of the most stressful

jobs in the world. And a lot of it does hinge

on decisions made by one person.

Ah, Swiss Radar, good evening,

DILMUN 6-1-1.

Nielsen hears from another plane in his airspace.

- Just leveling at flight level 2-6-0.

- DILMUN 6-1-1 is the call sign

for a Boeing cargo jet owned by the courier, DHL.

It departed from Bergamo, Italy,

and is flying through Swiss then German airspace,

on its way to Brussels, Belgium.

- DILMUN 6-1-1, squawk 7-5-2-4.

- 7-5-2-4,

6-1-1.

- DILMUN 6-1-1,

climb flight level 3-2-0.

Nielsen clears the flight to climb

to a higher altitude.

- Roger, climb flight level 3-2-0,

and requesting 3-6-0, thanks, if it's available.

Pilots ask for the most efficient

flight level that they can fly at,

and in this case 36,000 feet is much more fuel efficient.

- DILMUN 6-1-1, climb flight level 3-6-0.

- Climb flight level 3-6-0, DILMUN 6-1-1.

- Nielsen clears Flight 6-1-1 to 36,000 feet

and tracks the change.

You use flight strips to plan the traffic ahead.

With the strips and flight screen,

we have a good picture of what is going to happen.

- But at 11:30, Nielsen's night shift takes a turn.

Zurich, good evening, Bravo Tango Charlie--

Zurich, hello, Aero Lloyd 1-1-3-5.

Two transmissions come in together,

one at the workstation beside him.

There's an Airbus on approach to Friedrichshafen,

and another plane flying at a higher altitude,

in the "upper sector".

Aero Lloyd 1-1-3-5,

descending flight level 8-0.

- Nielson briefly responds to the Airbus now on approach.

- Aero Lloyd 1-1-3-5, roger, ah, call you back.

- He needs to identify the aircraft

now entering the upper sector.

- Station calling, say again, please.

Ah, Zurich, good evening.

- The aircraft is a Bashkirian Airlines Tupolev 1-54.

The Russian plane is slightly ahead of schedule,

crossing from Moscow to Barcelona.

- Bravo Tango Charlie 2-9-3-7,

level 3-6-0.

- 40-year-old Oleg Grigoriev

is Bashkirian Airlines' Chief Pilot.

Tonight, he's evaluating the 52-year-old captain,

Alexander Gross,

who has more than 10 years flying experience,

but has flown to Barcelona only once before.

- Smooth enough for you?

- So far.

- It's a bit bumpy back here.

- First Officer, Murat Itkulov,

41, is the captain's second pair of eyes.

- Then you better tighten your belt, huh?

- The flight is carrying a group of students

and some of their parents on a school trip to Spain.

As Nielsen gives the Tupolev crew their transponder code...

- Bravo Tango Charlie 2-9-3-7, squawk, ah--

7-5-2-0.

...inbound, the final approach fix

for I-L-S-- ...the Airbus crew

on approach tries to confirm their landing instructions.

- Yes, I expect so, call you back shortly.

Aero Lloyd 1-1-3-5, request lower.

- Aero Lloyd 1-1-3-5, descend flight level 7-0.

- Descending flight level 7-0, Aero Lloyd 1-1-3-5.

- As the Airbus gets closer to Friedrichshafen,

Nielsen calls the Tower Controller

to hand off the aircraft.

The desired connection is not possible.

- But he can't get through.

- Find me the number for Friedrichshafen Tower.

He tries again.

The desired connection is not possible.

Please check the number. - This isn't working either.

Aero Lloyd 1-1-3-5?

Aero Lloyd 1-1-3-5, go ahead, sir.

- I lost my phone connection to Friedrichshafen.

Can you please call them on 1-2-4 decimal 3-5

and tell them you're coming I-L-S 2-4 with 20 miles now?

Okay, will do.

- Thank you.

With the approaching Airbus handed off,

Nielsen returns to his other aircraft,

the Tupolev passenger jet that's westbound to Barcelona...

...and the Boeing cargo jet, northbound to Luxembourg.

Nielsen notices that both planes are moving

toward each other at 36,000 feet.

- Controllers will react.

They will do something to separate aircraft.

- Nielsen realises the Tupolev is soon scheduled to descend

to 35,000 feet.

- Bravo Tango Charlie 2-9-3-7,

descend flight level, 3-5-0, expedite,

I have crossing traffic.

- Descending an aircraft is an automatic response

for air traffic controllers,

because descending is a lot easier than climbing.

It's the easiest way to solve a conflict.

- Bravo Tango Charlie 2-9-3-7,

descend level 3-5-0, expedite descent.

Expedite descent to level 3-5-0...

...Lloyd,

- 1-1-3-5. - ...2-9-3-7.

- Yes. We have traffic in your position now at 3-6-0.

Zurich? From the Aero Lloyd 1-1-3-5.

- Yes, go ahead.

- We've made contact with Friedrichshafen airport.

But then...

...as the Aero Lloyd flight signs off...

- Affirm, bye-bye.

Bye-bye.

- The Boeing has disappeared from the controller's screen.

And the Tupolev's radar signal is lost.

- Bravo Tango Charlie 2-9-3-7?

Air traffic controller Peter Nielsen

has lost contact with two planes flying over southern Germany.

- Bravo Tango Charlie 2-9-3-7?

He called the aircrafts

and got no response.

He must have understood that it was a collision.

Near the town of Uberlingen,

people watch as fireballs fall out of the sky.

Huge sections of both planes have crashed to the ground.

There is no shortage of witnesses.

- First responders are on site within minutes.

And by dawn, crash investigators

from Germany's Federal Bureau

of Aircraft Accident Investigation,

the BFU, are there too.

- At the accident site, you just document

what the wreckage tells you.

- The wreckage of the Tupolev

is spread over four distinct areas.

- There would be maybe a hundred meters

between some parts.

So it clearly indicates that there must have been

an in-flight break-up of the Tupolev.

- Most of the Boeing is found in a forest

outside the village of Taisersdorf,

but one section is missing.

The only part of the Boeing that was missing

was the vertical tail,

and this later has been found together

with parts from the Tupolev,

indicating that the collision

took place between the two aircraft.

- Seventy-one people are dead.

Forty-five of them are Russian students

from the city of Ufa.

Investigators soon recover much of the wreckage,

including the black boxes from both planes.

- Hey. Over here.

- But before they get readouts from the black boxes,

investigators start to reconstruct the collision.

- So, this piece is interesting.

- We as accident investigators

did not have an idea

about the details of what exactly happened.

- This red paint could have come from the Boeing.

- Mm-hmm.

- And then over here...

The main issue is to understand

which aircraft part collide with the other one,

and which came from the impact to the ground.

- Okay. So, I've marked all the areas

where the red paint from the Boeing

transferred onto the Tupolev.

And we even found part of the Boeing's rudder

imbedded in the Tupolev right here.

- The only way this could have happened

is if the Tupolev

flew straight into the Boeing,

like... this.

- The question is, how can it happen

that two planes are at the same place

at the same time?

- Thank you.

Okay. So, we've compiled all of the radar data

from air traffic control.

- Okay, let's see what happened.

- Both planes are cruising at 36,000 feet.

They both start descending.

- At exactly the same time.

- Neither one is trying to get out of the way.

- Ninety degrees at the same altitude

is about as simple as it comes.

A turn, a descent of one, a climb of one.

So, how did we get to this point?

- It doesn't make sense.

Why would both planes descend?

- We all were of the opinion

that the air traffic control system in Europe

would be very, very safe.

So it was really hard to understand

that an accident like this could occur.

- Let's explore this.

- I'll get the weather data.

The basic way for pilots

to avoid collisions is called "see and avoid."

The pilots look out the window,

see the other aircraft, and don't collide.

- It was a clear night.

No moon at the time of the collision.

The sky was pitch-black .

- Even with anti-collision lights,

judging altitude and distance would have been impossible.

For jets operating at high altitudes,

moving at seven miles a minute,

finding some little dot even in a clear sky

is nearly impossible.

- So, we can eliminate that.

What about ATC separation?

Can we interview the controller yet?

- We're making arrangements to speak with him

about the accident.

- Where are we at with the T-CAS recovery?

- I'll check.

The T-CAS,

or Traffic Collision Avoidance System,

uses transponders on the aircraft

to transmit a plane's location to others.

If two aircraft appear to be on a collision course...

Traffic. Traffic.

- ...an alarm sounds,

warning pilots to change course.

- T-CAS is intended for when we need a last-ditch effort

to just keep them from hitting.

- Yeah. Thank you.

We got the Tupolev's T-CAS,

but no luck on the Boeing. It's too damaged.

- The major question for us:

Did the T-CAS computer work as per design?

The T-CAS computer of the Boeing was destroyed completely.

And that was a problem.

- If T-CAS is at fault,

it could threaten the safety

of air travel throughout the world.

Investigators looking into the Uberlingen

mid-air collision examine the T-CAS data

from the Tupolev plane

to determine if it was working properly.

- Wait a sec...

The Tupolev's T-CAS recorded data for both planes.

- There's an identical set of files for both flights.

- That was a big moment in the course of the investigation,

and we were very happy about that.

- Investigators compare the T-CAS altitude data

with the radar data from both planes.

- The altitudes match perfectly.

- What instruction did T-CAS give each plane?

Start with the Boeing.

- Did T-CAS provide each aircraft

with the proper instructions to avoid each other?

- It told them to descend.

- Which the Boeing did.

Now the Tupolev.

- Investigators discover that T-CAS correctly

advised the Tupolev pilots to climb.

- But they descended,

just like the Boeing.

So why didn't they follow the T-CAS instruction?

T-CAS did what T-CAS should have done.

If pilots were to follow the T-CAS instruction,

T-CAS would have prevented the accident.

- Investigators turn to the Tupolev's

cockpit voice recording, or CVR,

to determine why the Russian crew

disobeyed the T-CAS instruction.

Look here,

on the VSI,

there's a plane approaching on our left.

- They first became aware of the Boeing

two-and-a-half minutes before the collision.

- They're still more than 25 miles apart.

It's ample time to avoid the Boeing.

- So why didn't they?

- We have the same altitude.

It's coming towards us.

No, he has a parallel heading.

- For the next minute-and-a-half,

the crew discusses the Boeing's position.

Here, visually...

...this is showing us zero.

- Zero on the T-CAS means there is no difference

in altitude between them and the approaching Boeing.

- They seem unsure if the Boeing is actually a threat.

- Agreed. But T-CAS should warn them

if the Boeing is getting too close.

Traffic. Traffic.

- There it is. Traffic. Traffic!

Traffic!

Traffic. Traffic.

Fifty seconds before impact,

the T-CAS issues the first aural warning

when the oncoming plane is less than 10 miles away

and closing fast.

Traffic. Traffic.

- Moments later, the crew receives an instruction

from air traffic control.

Bravo Tango Charlie 2-9-3-7,

descend flight level, 3-5-0, expedite.

I have crossing traffic.

- Descend.

Followed by a different instruction

from T-CAS.

Climb. Climb.

Climb. Climb.

- The crew got conflicting instructions.

- T-CAS told the crew to climb,

the controller told them to descend.

- Climb. Climb. - It says climb.

- The controller is guiding us down.

- Descend? Really? We're going to descend?

- The captain follows the Chief Pilot's command

and puts the plane into a steep descent.

Bravo Tango Charlie 2-9-3-7,

descend level 3-5-0,

expedite descent.

- Descend level 3-5-0,

Bravo Tango Charlie 2-9-3-7.

Yes, we have traffic in your position now at 3-6-0.

Moments from disaster,

T-CAS issues a final command.

Increase climb.

Increase climb. Increase climb.

- But it comes too late.

- Well, there we have it.

The Chief Pilot followed the controller's instruction

to descend,

instead of the T-CAS's instruction to climb.

Each one of these guys got T-CAS training.

They should have known that T-CAS is the final authority.

- So why did the Chief Pilot listen to the controller

instead of T-CAS?

Investigators of the Uberlingen disaster

examine the T-CAS training of the Russian crew

to determine why they followed the ATC instruction

instead of T-CAS.

- Hey. I think I found something.

"T-CAS 2000 is intended as a back-up

to visual collision avoidance,

application of right-of-way rules

and ATC separation services."

- A back-up?

Look at this.

"For the avoidance of in-flight collisions,

instructions issued by ATC is the most important tool.

T-CAS is an additional instrument."

- So, if it comes down to T-CAS versus ATC,

the Russian pilots go with the ATC's instructions.

- It seems that way.

- We asked Russian flight crews and pilots told us,

yes, it's a back-up for ATC,

and so they explained that the flight crew

of the Tupolev did what they should have done.

- But the Boeing crew followed the T-CAS instruction.

Descend. Descend.

- I wonder if they informed the controller

they were descending.

The final approach fix

for I-L-S runway 2-4.

Did the controller know the Boeing

was also descending?

- Call you back shortly.

- Let's have a listen to the cockpit voice recording.

For the flight crews, there is a clear

operating procedure.

As soon as possible, they have to report it to ATC.

That was the reason why we had to listen

to the Boeing cockpit voice recorder.

Ah, Swiss radar. Good evening.

DILMUN 6-1-1.

DILMUN 6-1-1, climb flight level 3-6-0.

- Climb flight level 3-6-0, DILMUN 6-1-1.

- The flight is uneventful,

right up until a minute before the collision.

First Officer, Brant Campioni,

sees an opportunity to take a quick break.

- I just gotta use the facilities.

Handing over.

- Okay, taking over.

- Captain Paul Phillips takes control of the flight.

- Anything I can get you?

Nah, I'm good.

Traffic. Traffic.

Traffic.

- That's the T-CAS's first conflict alert.

Descend. Descend.

Descend. Descend.

- Traffic. Right there. - Yeah.

- Fifty seconds before the collision,

T-CAS warns the Boeing crew of the Tupolev's approach.

Increase descent. Increase descent.

- Increase? - Increase descent.

Increase descent.

- DILMUN 600...

T-CAS descend.

- No doubt about it.

They informed the ATC that they were descending.

Let's hear the rest.

Increase descent.

Increase descent. Increase descent.

- Descend.

Increase descent.

Descend hard!

Increase descent.

- Okay. So the Boeing crew did nothing wrong.

They followed T-CAS and informed the controller.

- But the controller instructs the Tupolev to descend twice,

warns them about the crossing traffic,

and then immediately,

the Boeing reports it's descending.

- He's still got two planes on a collision course.

- He's already been talking to the Tupolev crew,

so why didn't he just tell them to change course and climb?

If the controller knew the Boeing was descending,

why did he let the Tupolev also descend?

- A major part of the investigation

was to identify what the controller did

and how he did perform his job.

- Did Peter Neilson's actions

play a role in the Uberlingen mid-air collision?

- Bravo Tango Charlie 2-9-3-7, expedite descent.

to Peter Nielsen'sa: Inn

radio transmissions to determine how two planes

on his watch could have collided over Uberlingen, Germany.

- Let's start 30 seconds before the collision

when the Boeing pilots informed the controller of their descent.

Descending flight, level 7-0.

Aero Lloyd 1-1-3-5.

- It sounds like the controller was talking to a third aircraft.

- Just as the Boeing aircraft

advised the controller of their T-CAS descent...

- DILMUN 600. T-CAS descent-- - From the Aero Lloyd 1-1-3-5.

- Yes, go ahead.

- ...the controller received a simultaneous message

from another aircraft.

We made contact

with Friedrichshafen airport.

- So the call from the Boeing crew came in

at exactly the same time as the controller

was dealing with the Aero Lloyd flight.

When the Boeing pilots mentioned T-CAS descent,

he probably didn't even hear it, or it just

was something that he didn't process as an issue,

thinking that everything over on that airspace

was already taken care of.

- But juggling three planes isn't unusual.

There's got to be more to this.

- Investigators listen to earlier parts

of the ATC recording.

Zurich, good evening,

Bravo Tango Charlie 2-9--

Zurich, hello,

Aero Lloyd 1-1-3-5.

They hear the Tupolev

and Aero Lloyd Flights competing for Nielsen's attention.

Aero Lloyd 1-1-3-5, roger, ah--

...good evening. Bravo Tango Charlie 2-9--

- I'll call you back.

Station calling, say again, please.

Ah, Zurich, good evening.

Bravo Tango Charlie 2-9-3-7,

level 3-6-0.

Aero Lloyd 1-1-3-5, requesting lower.

- Aero Lloyd 1-1-3-5, descend flight level 7-0.

- During the last five minutes before the collision,

the workload increased very much.

Investigators hear Nielsen having difficulty

contacting the airport where the Aero Lloyd flight

was due to land.

The desired connection is not possible.

- Find me the number for Friedrichshafen Tower.

- How many times does he try calling Friedrichshafen?

- Seven. - He spent a lot of time

on something that should have taken seconds.

The desired connection is not possible.

Please check the number. - This isn't working either.

- So, how did he end up

in this situation in the first place?

Normally, an inbound call is just

a few seconds.

But dealing with the communication system

took a lot of time that then allowed

the two collision aircraft to get ever closer

at this very high rate of speed.

- Thanks for coming in.

- Investigators interview Peter Nielsen

to assess his workload on the night of the accident.

- So, at the time of the accident,

you seemed to be working two different workstations. Why?

- There are two controllers on the night shift,

but one controller always takes a rest

as traffic decreases for the night.

- You're off?

See you in a few hours.

They come back in the morning

when traffic picks up.

- And is that standard procedure?

- It's not written down anywhere in company policies,

but... management lets us do it.

- Okay.

So, 13 seconds before the collision,

the Boeing radioed that they were doing a T-CAS descent.

Did you hear that transmission?

- No, I didn't.

I guess I was dealing with the Aero Lloyd flight

approaching Friedrichshafen.

I couldn't get through to the airport.

The phone was down for some reason.

- Is there anything else you can think of that might help us?

- Yeah.

Normally, the computer system issues an alert

well before two planes get too close together.

But I never got that alert.

The air traffic control radar system

has what's called, "conflict alert system."

It's looking at the airplanes

and, based on their current speed,

and altitude, and heading,

is projecting out to see if airplanes

are coming into conflict with each other.

The controller was under very high pressure

during the last minutes.

Expedite descent to level 3-5--

Zurich, from the Aero Lloyd--

Bravo Tango Charlie 2-9-3-7.

- It was, at the end for him,

a really difficult situation.

- Was Peter Neilson fully equipped

to prevent the collision that cost the lives

of 71 people?

Investigators interview officials

from Skyguide to find out why Peter Neilson

never received a warning of the impending collision

above Uberlingen, Germany.

- Why were the control system's conflict alerts

and telephones both down?

What's this?

- A work order

for a computer upgrade.

A new software was to be implemented

on the main screen, which meant that the controller

had to work on the back-up system.

The software in the telephone system also had to be updated.

- So, is this why there was no

phone or visual conflict alert?

- Yes.

- But it doesn't say that anywhere.

Was Nielsen warned about this before his shift?

- Not that I'm aware.

- One other thing.

Why does management allow one of the controllers

working nights to be on break most of the shift?

- It started when there were three controllers at night.

- But there are only two now.

- We didn't change the practice.

- Thank you.

That was the way they did it,

one controller on screen and the other was on break.

And this was accepted by the management.

- Bravo Tango Charlie 2-9-3-7, descend flight level 3-5-0.

- Climb. - It says climb.

- The controller is guiding us down.

- Climb. - Descend? Really?

We're going to descend?

- Investigators now understand...

- Bravo Tango Charlie 2-9-3-7,

descend level 3-5-0, expedite descent.

Expedite descent to level 3-5--

Zurich? From the Aero Lloyd--

- Bravo Tango Charlie 2-9-3-7.

...why two flights...

- Increase descent. - Descend!

- Increase descent. - Descend hard!

...ended in disaster.

While completing their final report...

- BFU, hello.

What?

- ...the story of the Uberlingen mid-air collision

takes another tragic turn.

On February 24, 2004,

almost two years after the Uberlingen disaster,

Peter Nielsen is murdered in his front garden.

His wife and three children are witnesses to the crime.

- We couldn't believe it.

We couldn't believe it, because it was, for us,

like a TV story, and it was not real life.

But yes, it was real life.

- Did they catch the killer?

- Yeah.

Apparently his family was on the Tupolev.

- A Russian man, Vitaly Kaloyev,

is arrested for Peter Nielsen's murder.

Kaloyev's wife and two children

were killed in the Uberlingen collision.

He tells police he went to Nielsen's house

seeking an apology.

But Nielsen isn't found at fault

for the collision in the BFU's final report.

Zurich? Hello, Aero Lloyd...

Instead, it concludes he was unable

to safely carry out the tasks required of him.

The BFU points to the fact that Nielson was working alone

as a cause for the accident.

Bravo Tango Charlie 2-9-3-7,

descend flight level, 3-5-0. Expedite.

I have crossing traffic. - Descend.

- But the report also highlights deficiencies

in aviation regulations

that allowed for the Russian pilots' confusion

- over the use of T-CAS. - Climb.

- It says climb. - Climb.

- The controller is guiding us down.

- Descend? We're going to descend?

Climb. Climb. Climb.

- The BFU's most prominent recommendation is simple.

- Pilots have to follow the T-CAS instruction,

not to follow the ATC instruction,

because T-CAS is a safety net.

- Eventually, four Skyguide middle managers,

who weren't even working the night

of the Uberlingen disaster,

are convicted of negligent homicide.

This accident, it was really a watershed event.

A lot of things had to fall into place

just the wrong ways for this to occur.

And it changed a lot of things.

A lot of the way people looked at ATC,

collision avoidance, and it really woke a lot of people up.

In 2005,

Vitaly Kaloyev is convicted

of the premeditated homicide of Peter Nielsen.

Two years later, he's released from prison.

Today, nine steel "pearls"

representing a torn necklace,

mark the locations where victims' bodies were found.

And a memorial inside Skyguide

marks both the date of the collision

and that of Peter Nielsen's murder.

Subtitling: difuze