Original subtitles

NARRATOR: A regular commercial flight

to an extraordinary part of the world.

JOHN: A lot of tourists fly in just for the scenery.

NARRATOR: Thai Airways 311 is bound for Kathmandu. But it never arrives.

AIR TRAFFIC CONTROLLER: Thai 311, Kathmandu. Please report your position.

DAVID MCNAIR: Until the airplane is found

it's difficult to figure out what might have happened.

NEPALI INVESTIGATOR: This is where we search.

NARRATOR: A high-altitude trek leads investigators

to one of the most remote places on Earth.

DAVID ROHRER: You couldn't tell that you had

an Airbus A310 aircraft there.

You couldn't even tell you had two engines.

NARRATOR: How can they ever hope to piece together what happened?

DAVID ROHRER: Right away you knew you were really

gonna be in a difficult situation.

♪ ♪

NARRATOR: It is mid-summer in the Himalayas.

Monsoon season, when shifting winds and sudden rains

sweep across the jagged mountain landscape.

Just above the awesome peaks flies Thai Airways Flight 311.

The pilot flying is Captain Preeda Suttimai.

His first officer is Phunthat Boonyayej.

FO. BOONYAYEJ: I will never get tired of seeing these mountains.

CAPT. SUTTIMAI: It truly is an extraordinary sight, brother.

NARRATOR: The flight's ninety-nine passengers

are a mix of Nepalese nationals and international tourists

all headed to Kathmandu.

JOHN: Kathmandu is a popular tourist destination.

It's a mountainous airport

and a lot of tourists fly in just for that, for the scenery.

NARRATOR: The Thai Airways plane is an Airbus A310,

a medium-to-long-range twin jet.

JOHN: The A310 overall is a fantastic airplane.

It has a range of eight hours

and it can carry 20 tons at a decent altitude.

The flight from Bangkok to Kathmandu is expected to take

roughly three and a half hours.

The Nepalese capital lies at more than 4,500 feet

above sea level.

The approach requires navigating

some of the world's highest mountains.

FO. BOONYAYEJ: Kathmandu, Thai 311. Request descent.

Kathmandu, Thai 311. Do you read?

JIM: The first attempts that the flight crew had

with air traffic control, they called three times

and got no response at all.

FO. BOONYAYEJ: Kathmandu, Thai 311. Do you read?

JIM: The acoustics were not very good.

There was a lot of echoing on the frequency.

Maybe it had been caused by the mountains.

FO. BOONYAYEJ: Kathmandu, Thai 311.

AIR TRAFFIC CONTROLLER: 311, Kathmandu. Go ahead.

NARRATOR: Finally, the Nepalese controller hears the call.

FO. BOONYAYEJ: Request descent.

AIR TRAFFIC CONTROLLER: Thai 311, we have negative traffic at or above

flight level one-five-zero within our juris...

except one in Nepal at two-zero-six.

You are cleared for descent.

JIM: The controller, he was relatively inexperienced.

He had nine months' experience.

You know, he's not a complete rookie

but at the same time he's got a lot to learn yet.

ANNOUNCEMENT: Ladies and gentlemen,

we will soon begin our descent into Kathmandu.

Please stow away your tray tables, raise your seat backs

and fasten your seat belts in preparation for landing.

NARRATOR: The flight is now about 30 minutes

from its destination.

CAPT. SUTTIMAI: Lots of clouds. Let's go through.

NARRATOR: Kathmandu's Tribhuvan International Airport

is one of the most challenging in the world.

The mountains that tower above the capital force pilots

to descend much more steeply than at other airports.

JIM: When I look at the approach that

the aircraft was going to be flying going into Kathmandu,

I'm definitely struck by the steepness of the approach itself

and the gradient of the terrain in the area.

CAPT. SUTTIMAI: Go ahead. Would you request for runway zero-two please?

FO. BOONYAYEJ: Thai 311, request zero-two.

AIR TRAFFIC CONTROLLER: Thai 311, confirm requesting zero-two.

FO. BOONYAYEJ: Confirm.

NARRATOR: The pilots have requested a straight-in approach

from the south to runway two.

It will keep them clear of high mountains north of the airport.

But as they get closer, things change.

AIR TRAFFIC CONTROLLER: Thai 311, Kathmandu.

FO. BOONYAYEJ: Go ahead, Thai 311.

AIR TRAFFIC CONTROLLER: Thai 311, for your information

runway zero-two not available due to poor visibility

and heavy rain toward that side.

You'll have to take runway two-zero.

NARRATOR: Sudden bad weather means the only approach

now available is from the north.

It requires circling north of the airport

to land on the opposite runway,

a maneuver the captain does not want to make.

CAPT. SUTTIMAI: We need runway zero-two for the straight-in approach.

JOHN: You'd be challenged at the notion of

doing a circling approach in a mountainous environment.

It's one thing to do it over an island

say in the sea without any obstacles.

It's another thing to do it surrounded by mountains.

♪ ♪

CAPT. SUTTIMAI: I guess we can't make it, brother.

Please check the field to Calcutta.

NARRATOR: The captain decides to abandon the landing

and divert to an airport in India.

FO. BOONYAYEJ: Fuel. We got enough to get to Bangkok.

CAPT. SUTTIMAI: And for Calcutta, how much do we need?

Eighteen, 14, 42?

NARRATOR: For passengers, diverting to Calcutta

would mean landing more than 400 miles

away from their destination.

AIR TRAFFIC CONTROLLER: Thai 311, I've just confirmed

that runway zero-two is now also available.

Report two-five DME.

CAPT. SUTTIMAI: Wait a minute.

NARRATOR: It seems the unpredictable weather has changed again.

It's good news.

CAPT. SUTTIMAI: Kathmandu, Thai 311. Confirm runway zero-two available?

AIR TRAFFIC CONTROLLER: Confirmed. Runway zero-two is now available.

CAPT. SUTTIMAI: That's lucky.

NARRATOR: The straight-in approach from the south is once again clear.

But the plane is now too close to the runway to descend safely.

JIM: They were a little bit high for the position

that they were at in relation to the airport.

CAPT. SUTTIMAI: Kathmandu, Thai 311. We cannot make approach now.

We will need to turn back to Romeo and climb

to one-eight-thousand feet and start our approach again.

NARRATOR: The captain decides to turn around and try again.

It should give him the distance he needs

for a safe, controlled descent.

Using the flight management system,

First Officer Boonyayej looks up a navigational waypoint,

called Romeo, to restart their approach.

But there's a problem.

The system won't lock in the flight path to Romeo.

FO. BOONYAYEJ: It disappeared.

CAPT. SUTTIMAI: It's Romeo 27, isn't it?

FO. BOONYAYEJ: Ro-me-o.

CAPT. SUTTIMAI: Kathmandu, what is the visibility?

AIR TRAFFIC CONTROLLER: Thai 311, stand by for tower observation and visibility.

NARRATOR: Flying in dense cloud cover,

the pilots' view ahead is extremely limited.

They want to know when they can expect to see the airport.

CAPT. SUTTIMAI: Level change. GPWS: Terrain. Terrain. Pull up.

NARRATOR: A ground proximity warning suddenly begins to sound.

GPWS: Pull up. Pull up. Airspeed low.

FO. BOONYAYEJ: Turn back! Turn back!

CAPT. SUTTIMAI: It's false. It's false.

GPWS: Terrain. Pull up. Don't sink.

♪ ♪

Terrain. Terrain. Pull up. Pull up.

FO. BOONYAYEJ: Oh my God!

AIR TRAFFIC CONTROLLER: Thai 311, please report your position.

Thai 311, Kathmandu. Please report your position.

NARRATOR: In the mountains of Nepal, a search is underway

for Thai Airways Flight 311.

The Airbus carrying 113 people vanished

on approach to Kathmandu.

Nepal has moved quickly

to set up a Royal Commission of investigators.

NEPALI INVESTIGATOR: This is the airport.

Flight 311 was coming in from the south, here.

DAVID MCNAIR: Until the airplane is found,

it's difficult to figure out what might have happened.

NEPALI INVESTIGATOR: This is where we search.

♪ ♪

NARRATOR: They search an area covering

dozens of square miles south of Kathmandu.

DAVID MCNAIR: And the search of course started in the south

because it came in from the south.

NARRATOR: A methodical search eliminates territory sector by sector.

NEPALI INVESTIGATOR: Where is this thing?

NARRATOR: The plane is nowhere to be found.

Time is of the essence.

The unpredictable Himalayan weather could bring heavy rains

at any moment, making the search all but impossible.

As the mountain search continues, investigators

interview air traffic control, hoping for any kind of lead.

AIR TRAFFIC CONTROLLER: We don't have radar here,

so I can't help you with the airplane's location.

JIM: A radar is a line of sight tool.

It doesn't penetrate through mountains or anything like that.

So in a mountainous area like Kathmandu, your radar coverage

would be limited to some degree

because it would be blocked by the mountains themselves.

AIR TRAFFIC CONTROLLER: I just rely on what the pilots tell me.

JIM: In a non-radar environment, they have a mental picture,

and that picture is really painted by the words

that the pilot reports to them.

They don't have an exact location.

It's almost like working blindfolded.

AIR TRAFFIC CONTROLLER: They were going to restart their approach.

Their last reported position was here,

14 miles to the south of the airport.

CAPT. SUTTIMAI: Kathmandu, Thai 311. We cannot make approach now.

We will turn back to Romeo and climb

to one-eight-thousand feet to start our approach again.

AIR TRAFFIC CONTROLLER: To redo the approach,

they would have to turn back towards the south.

There was one thing.

At one point they mentioned a technical fault.

But a few seconds later they said they were fine.

NARRATOR: A mysterious technical fault raises suspicion.

But at this point, there's no way of knowing

if it played any role in the plane's disappearance.

DAVID MCNAIR: They knew the aircraft had some technical problem.

That's what they were told.

You didn't know whether it was a radio fault,

a navigation system fault, so we wondered what it was.

NARRATOR: It's been almost 48 hours

since Thai Airways Flight 311 disappeared in the Himalayas.

Investigators have yet to find the aircraft.

But now they're about to get an important break.

Local villagers report that they found

aircraft debris north of Kathmandu.

DAVID MCNAIR: Some people where the airplane crashed had heard the crash,

and they couldn't communicate with anybody

as to where it went 'cause they didn't have the means to do so.

NEPALI INVESTIGATOR: Are you sure you don't mean

down here to the south of the city?

NARRATOR: Investigators can't quite believe it.

The reported crash site

is nowhere near the area they've been searching.

DAVID ROHRER: I don't think they ever in their wildest imagination

thought the airplane was north of the airport.

NARRATOR: North of Kathmandu, near the border with Tibet,

the Himalayan peaks soar to an altitude of 20,000 feet.

These northern summits are the reason almost all planes

approach Tribhuvan Airport from the south,

where the mountains are closer to 8,000 feet.

NEPALI INVESTIGATOR: Send out the helicopters.

Tell them to start searching to the north of the airport.

NARRATOR: Later that day, 27 miles north of Kathmandu,

search crews find the remains of Thai Airways Flight 311.

The point of impact is a steep rock face more than 11,000 feet

up the side of a remote mountain.

DAVID MCNAIR: It hit essentially a vertical rock face

and then the whole aircraft just tumbled down into a valley.

There was some small evidence of fire,

but mostly just total destruction of the aircraft.

NARRATOR: None of the 113 people on board have survived.

DAVID MCNAIR: It immediately created some mysteries as to

what might have happened, why the airplane got to

a place that it was not expected.

NARRATOR: The challenge for investigators

is unlike anything they've encountered before.

The terrain is so extreme

helicopters can't land near the impact zone.

The team will have to trek more than 3,000 feet

up from the base camp to reach the wreckage.

♪ ♪

It's a treacherous five-hour hike.

NEPALI INVESTIGATOR: Okay. I gotta stop.

DAVID MCNAIR: It's a dangerous area. You had to be very, very careful.

At a high altitude you tend to end up with hypoxia.

♪ ♪

NARRATOR: It isn't long before the mountains let it be known

just how dangerous they can be.

NEPALI INVESTIGATOR: What happened? What's going on?

DAVID MCNAIR: One of the investigators died.

NARRATOR: A British investigator for Airbus

suffers fatal complications from hypoxemia, a

lack of oxygen in the blood due to thin air at high altitude.

DAVID MCNAIR: It's bad enough that people die in the accident,

but you don't want other people dying

trying to solve the accident

or recover things from the accident site.

And so that was a shock.

NARRATOR: It's now brutally clear to everyone:

On this mission the stakes could not be higher.

NARRATOR: Deep in the Himalayan mountains,

Nepal's Accident Investigation Commission

makes its way toward the Thai Airways crash site.

The team includes experts from around the world,

including Canada's David Rohrer.

DAVID ROHRER: You're there to hopefully find something

to prevent recurrence, to save somebody else

from having that same tragedy in their lives

or have a similar outcome. That's why you're there.

♪ ♪

NARRATOR: Rohrer is confronted with a scene

of total devastation.

DAVID ROHRER: The level of destruction was enormous.

You couldn't tell that you had an Airbus A310 aircraft there.

I mean, you couldn't even tell you had two engines.

NARRATOR: The first big question they have is,

how did Thai Airways Flight 311 end up here?

The Airbus should never have been

flying north of the airport.

Searchers soon find the cockpit voice recorder.

But that won't reveal the flight path.

NEPALI INVESTIGATOR: Bring that to base.

NARRATOR: Investigators already know the airport has no radar data.

Their best chance of discovering how the plane reached

this fatal impact zone is to find the flight data recorder.

DAVID ROHRER: Right away you knew that if you didn't have the FDR

then you were really gonna be in a difficult situation

in terms of trying to determine cause or probable factors.

DAVID ROHRER: Still no sign of the FDR?

NEPALI INVESTIGATOR: No. Unfortunately not.

NARRATOR: The intensive high-altitude effort

has already killed one team member.

Investigators know that their time on the mountain

will be limited.

NEPALI INVESTIGATOR: Right over there.

NARRATOR: An airport hangar in Kathmandu is the final stop

on a long journey for wreckage collected from the mountainside.

DAVID ROHRER: The Sherpas would bring down the pieces

that we identified down to the landing zone.

Then the Nepalese army in their helicopters

would put them in nets

and then sling them down to the hangar at the airport.

NARRATOR: With still no word on the plane's flight data recorder,

investigators review the A310's maintenance records.

DAVID MCNAIR: In any investigation, you don't just sit

and wait for the recorders. You start doing work right away.

For example, were there any problems with the aircraft

before the accident?

NARRATOR: They already know that the Thai Airways pilots

reported an unknown technical fault to air traffic control.

DAVID ROHRER: It's a red flag, and there's so many

different areas that could be called a technical fault.

You know, was it a configuration issue? Was it a power issue?

Was it a landing gear issue?

It just opens up Pandora's box of what it can be.

DAVID ROHRER: Hey, look at this. The day before the flight

there was a circuit breaker failure on the plane.

DAVID MCNAIR: There was a recurring problem with the XP-205 bus.

And that bus was related to navigation equipment,

so we were kind of thinking,

well, perhaps we better look at that in more detail.

NARRATOR: The XP-205 bus carries electrical power to several

important systems, including the plane's navigation system.

NEPALI INVESTIGATOR: Maybe the bus failed

while they were in flight.

DAVID ROHRER: It's possible.

NARRATOR: A malfunction in the navigation system

could explain the location of the crash.

DAVID ROHRER: If that bus failed it would wipe out

the co-pilot's electric instruments,

which would show his position and his navigation.

That would be pretty critical.

But in order to prove their theory, they'll have to

track down the XP-205 bus

amidst piles of burnt and twisted debris.

NEPALI INVESTIGATOR: It's hard to tell what we're even looking at here.

DAVID MCNAIR: Given the destruction of the aircraft,

very difficult to track down those types of technical issues.

NARRATOR: As team members comb through the wreckage,

the investigation takes an unexpected turn.

♪ ♪

DAVID ROHRER: Excuse me. Can I help you?

DAVID MCNAIR: During the investigation, one of the family members

were asking for a circuit board just because

it somehow would link them to their loved one.

NARRATOR: The unusual request leads to an incredible find.

DAVID MCNAIR: That's when we actually found the internal mechanism

of the recorder we were missing, which was quite amazing.

NARRATOR: The FDR should provide crucial data on the plane's speed,

direction and altitude throughout the flight.

DAVID MCNAIR: You always hope that luck is on your side,

that things will happen to your benefit.

And those are the kind of moments

you really hope for as an investigator.

NARRATOR: It's the breakthrough they've been waiting for,

evidence that could reveal how a plane flying south

of the airport ended up slamming into mountains to its north.

DAVID ROHRER: Ready? Okay. Start it up.

NARRATOR: The cockpit voice recorder from Thai Airways Flight 311

is finally ready for analysis.

CAPT. SUTTIMAI: Lots of clouds. Let's go through.

NARRATOR: Investigators hope to hear something that might

help explain why the Airbus hit a mountain at over 11,000 feet.

AIR TRAFFIC CONTROLLER: Thai 311, Kathmandu.

CAPT. SUTTIMAI: Go ahead. Would you request for runway zero-two please?

FO. BOONYAYEJ: Thai 311, request zero-two.

AIR TRAFFIC CONTROLLER: Thai 311, confirm requesting zero-two?

FO. BOONYAYEJ: Confirm.

NARRATOR: As they initiate their descent, all seems normal.

CAPT. SUTTIMAI: I guess we can't make it, brother.

Please check the fuel to Calcutta.

NARRATOR: But as the captain considers diverting to Calcutta,

the atmosphere in the cockpit seems to change.

FO. BOONYAYEJ: Fuel. We got enough to get back to Bangkok.

CAPT. SUTTIMAI: And for Calcutta, how much do we need?

Eighteen? Fourteen? Forty-two?

DAVID ROHRER: He's really getting frustrated with his first officer.

JOHN: I got the impression that the answers from the

first officer were not what the captain was looking for.

They weren't communicating properly with each other.

AIR TRAFFIC CONTROLLER: Thai 311, I've just confirmed that

runway zero-two is now also available. Report two-five DME.

CAPT. SUTTIMAI: Wait a minute.

Kathmandu, Thai 311. Confirm runway zero-two available?

NARRATOR: Investigators then notice

something else out of the ordinary.

AIR TRAFFIC CONTROLLER: Confirmed. Runway zero-two is now available.

CAPT. SUTTIMAI: Request surface condition, please.

DAVID ROHRER: Wait, wait a minute. Stop.

NARRATOR: The pilot on the radio is not the first officer.

DAVID ROHRER: It's the captain.

Why was the captain speaking with the controller?

NARRATOR: As the pilot flying, the captain

should never have been speaking with air traffic control.

JOHN: It's up to the first officer, as the non-flying pilot,

to do the communication. But it didn't unfold that way.

DAVID ROHRER: Normally division of duties in a cockpit's

very important in sharing workload.

But in this case I noticed that the captain was in many cases

taking over the radio transmission work.

CAPT. SUTTIMAI: Speed brake in. Flap 15.

FO. BOONYAYEJ: Speed brake in. Flap 15 selected.

NARRATOR: As they keep listening,

they hear the captain's frustration grow.

CAPT. SUTTIMAI: Damn it! The flaps cannot be extended.

DAVID MCNAIR: The flaps would not extend to full configuration,

which for the Kathmandu approach is essential.

CAPT. SUTTIMAI: It's too late to make a landing. It's too late.

FO. BOONYAYEJ: We can request a return.

CAPT. SUTTIMAI: Damn it! Kathmandu, Thai 311.

Request to maintain 10,500

and request to go back to Calcutta due to technical.

NARRATOR: It's now clear that the technical problem

has nothing to do with a circuit breaker.

It's the wing flaps. They won't extend to 15 degrees.

DAVID ROHRER: When they went to 15 and 15,

of course they didn't get 15 and 15.

They got the one chime and they had a flap fault.

NARRATOR: But just how serious a problem is it?

Will it affect the captain's ability to control his plane?

CAPT. SUTTIMAI: Hey. The flaps have extended.

NARRATOR: The recording soon tells them that the flap issue

is quickly resolved.

JOHN: They did cycle the flaps. They did correct the problem.

CAPT. SUTTIMAI: Back to normal now. Can we make a left turn to Romeo?

AIR TRAFFIC CONTROLLER: Understand operation normal.

And you'd like to make an approach?

CAPT. SUTTIMAI: Affirm. Affirm.

NARRATOR: The situation appears to be stabilizing.

AIR TRAFFIC CONTROLLER: Thai 311, clear Sierra approach.

Report one-zero DME leaving 9,500.

NARRATOR: But the captain's frustration soon returns.

CAPT. SUTTIMAI: We can't land at this time. We have to make

a left turn back to Romeo and start our approach again.

JOHN: Communication with ATC was anything but great.

It was fragmented. It was unclear.

AIR TRAFFIC CONTROLLER: Thai 311, go ahead your DME distance.

CAPT. SUTTIMAI: We are nine DME, 10,500 feet.

Answer, please.

Answer, please.

JIM: Repeated requests to return to Romeo were

pretty much unanswered.

NARRATOR: Investigators now wonder...

CAPT. SUTTIMAI: Kathmandu, Thai 311. Can we make our left turn back now?

NARRATOR: Does the Thai Airways crew keep flying towards the mountains

because they don't have clearance to change course?

CAPT. SUTTIMAI: We'll climb and turn to the right.

NARRATOR: But despite lacking clearance,

the captain takes matters into his own hands

and turns his plane right,

heading back to the start of the approach.

♪ ♪

FO. BOONYAYEJ: They're all gone. They've disappeared!

NARRATOR: Moments later, there is more uncertainty in the cockpit.

CAPT. SUTTIMAI: It's Romeo 27, isn't it?

FO. BOONYAYEJ: Ro-me-o.

DAVID MCNAIR: Also, the captain seemed to be getting frustrated

with the co-pilot's efforts

to put things in the navigation system.

FO. BOONYAYEJ: This thing failed again.

DAVID ROHRER: Why is he having such a hard time inputting the waypoint?

NARRATOR: Then, investigators hear

a surprising question from the first officer.

FO. BOONYAYEJ: Are we going north?

DAVID MCNAIR: The co-pilot said something like,

"We're going north, huh?"

with that inflection like it's a mitigated-type question.

NARRATOR: The recording presents a troubling contradiction.

Though clearly frustrated with air traffic control

and with his co-pilot, it seems the captain

managed to turn south away from the mountains.

Yet, minutes later, they hit a wall to the north.

GPWS: Terrain. Terrain. Pull up.

FO. BOONYAYEJ: Turn back. Turn back!

CAPT. SUTTIMAI: It's false. It's false.

NARRATOR: How they ended up slamming into a mountain

they were supposed to be flying away from remains a mystery.

GPWS: Terrain. Terrain. Pull up.

FO. BOONYAYEJ: Oh my God!

NARRATOR: In Nepal, investigators have ruled out

the possibility that a faulty circuit breaker

caused the Thai Airways 311 disaster.

DAVID MCNAIR: Had the XP-205 bus failed, it would have

fired off some warning chimes, which I'm sure

they would have talked about, which they didn't.

And so I think that that was probably the main reason

we discounted it as a factor.

NARRATOR: They wonder if the work records

of the two Thai Airways pilots

can shed any new light on the investigation.

The captain's record reveals he was a highly trained pilot

who had flown to Kathmandu many times.

DAVID ROHRER: He was impressive, and I think everybody in the company

had identified him as a person

who was going to go right to the senior levels of the company.

The co-pilot was older than the captain.

He had a lot of experience as well.

DAVID ROHRER: The first officer has flown into Kathmandu

14 times in the last year.

NARRATOR: But as investigators look more deeply

into the first officer's record,

they make a surprising discovery.

DAVID ROHRER: Thai Airways, they categorized you

based on whether you were gonna be captain material

or whether you were going to be first officer material only.

Interestingly enough, in their assessment

they categorized for the first officer in this case

that he would not be captain.

I've always thought that if you tell somebody,

you're limited, I will hire you but you're limited,

well, maybe they'll fulfill that prophecy.

DAVID ROHRER: It still doesn't explain

how they ended up way up here to the north.

NARRATOR: Flight 311 flew 27 miles north of the airport into

airspace commercial airliners normally avoid at all cost.

DAVID ROHRER: Is that the data from the FDR? Great.

NARRATOR: With the FDR data now recovered, investigators have

their first chance to analyze the plane's deadly flight path.

DAVID MCNAIR: 'Cause recorders will give you

latitude and longitude.

It gives you a nice track as to where the airplane went.

DAVID ROHRER: First, let's have a look at

what they were intending to do.

Can you pass me the published approach?

NARRATOR: Thai Airways' approach to Kathmandu

is from the south. The crew wanted to land on runway two.

DAVID ROHRER: Okay. Roughly here is where

they would have decided on the missed approach.

This is where they were supposed to go.

Let's see what they actually did.

♪ ♪

NARRATOR: The data shows Flight 311

proceeding north toward Kathmandu.

Everything seems to be in order.

DAVID ROHRER: And right here they're looping around

to restart their approach, right?

♪ ♪

They were supposed to level out. They just kept turning.

NARRATOR: Instead of straightening out and heading to Romeo,

Flight 311 does a complete 360-degree turn.

DAVID ROHRER: When I saw it, I was amazed because

I couldn't understand why they would want to do that.

DAVID ROHRER: It just doesn't make any sense.

NARRATOR: Why the Airbus flew in a complete circle

back on a collision course with mountains north of the airport

is a mystery.

Investigators must solve it to understand why 113 people

died aboard the Thai Airways flight.

NEPALI INVESTIGATOR: Ready?

DAVID ROHRER: Ready. Fire it up.

NARRATOR: In search of answers,

they turn to a flight simulator.

DAVID MCNAIR: In terms of simulator testing,

the one thing that it allows the investigators to do

is to replicate what happened

and understand what the crew would see

or any other problems that they would face.

NEPALI INVESTIGATOR: The captain just took over

communications with the controller.

DAVID ROHRER: Yeah, okay.

CAPT. SUTTIMAI: Kathmandu, Thai 311. Confirm runway zero-two available?

NARRATOR: At this point, the captain is flying the aircraft,

monitoring the instruments and speaking to the controller

all on one of the steepest, most difficult descents

in aviation.

CAPT. SUTTIMAI: Speed brake in. Flap 15.

FO. BOONYAYEJ: Speed brake in. Flap 15 selected.

CAPT. SUTTIMAI: Damn it! The flaps cannot be extended.

NARRATOR: The flap issue is temporary.

But time spent resolving it forces a delay.

They can no longer make the straight-in landing.

DAVID ROHRER: Let's see. Okay. No.

We are too high and too close for the approach.

The only choice is to circle back and do another approach.

NEPALI INVESTIGATOR: The controller hasn't given clearance.

He keeps asking for the aircraft's altitude

and distance from the airport.

DAVID ROHRER: Hang on. We are getting very close

to the mountains, right? We need to make a turn soon.

NARRATOR: The autopilot takes the plane to a selected heading

in the shortest way possible.

In this case, that would mean turning to the left.

NEPALI INVESTIGATOR: The controller said there's traffic to the left.

DAVID ROHRER: Okay, there is a lot going on here right now.

NEPALI INVESTIGATOR: And he still hasn't cleared you to go back to Romeo.

NARRATOR: Needing to turn before he reaches

the mountains north of Kathmandu

and with traffic on his left,

the captain decides to override the autopilot.

CAPT. SUTTIMAI: We'll climb and turn to the right.

NARRATOR: He can turn right by turning the heading knob

incrementally in the same direction.

DAVID MCNAIR: The airplane was turned

most likely by changing the heading bug.

In other words, the captain has that option.

He just turns a heading selector and the airplane will turn.

NEPALI INVESTIGATOR: Watch your turn. You're center level off.

DAVID ROHRER: Oh. Yeah. Right.

JOHN: The climb, turn, descend with an autopilot,

that's tough to do. And he was doing all of that in the turn.

NEPALI INVESTIGATOR: Okay. You're starting to fly south now

and should straighten out.

DAVID ROHRER: Yes.

NEPALI INVESTIGATOR: But he gets yet another call.

The controller tells him to lower the altitude

to 11,500 feet due to traffic in the area.

DAVID ROHRER: Okay.

AIR TRAFFIC CONTROLLER: Thai 311, descend

to flight level one-one-thousand-five-hundred.

DAVID ROHRER: It started to really become apparent that, you know what?

With all the distractions,

with all the workload that the captain had,

that, eventually, you know, the monkey climbed on his back

and he took on the whole load of the operation.

NARRATOR: Investigators are close to a breakthrough.

NEPALI INVESTIGATOR: And this is the moment

they should have stopped adjusting the heading.

NARRATOR: The simulation gives them a sense

of the mounting pressure in the Thai Airways cockpit.

An extremely busy captain flying a challenging approach

attempts an improvised right turn.

JOHN: He's trying to do too many things at once.

He's asking to go to a point,

he's trying to fly the airplane on the autopilot

and he's starting to lose the 3D picture

that he has in his head where he is.

NARRATOR: Without realizing it, he turns the heading knob too far.

DAVID ROHRER: He turned it one too many times and did a full circle.

JOHN: Each time he has to reach up and change his heading,

he has to take his eyes off the ball.

What's the one thing that we never do,

is take our eyes off the ball.

Well, each time he reaches up to select a different button,

he takes his eye off of the screen.

DAVID MCNAIR: The captain took on too much himself where

the point he was distracted from his primary task,

which is to navigate the airplane.

NARRATOR: Investigators finally understand how the plane

ended up heading in the wrong direction.

But they still wonder why the crew

didn't notice the mistake in time.

NEPALI INVESTIGATOR: After he did the turn,

they kept flying north for more than five minutes.

NARRATOR: As the pilots head toward disaster,

they struggle to input the Romeo waypoint.

Their frustration with the flight computer

should be a warning sign. Romeo is now behind them.

DAVID ROHRER: How could they not notice?

NARRATOR: Why the Thai Airways crew failed to notice

that they had turned their plane 360 degrees

back towards the towering Himalayan mountains

is one of the last mysteries investigators want to solve.

DAVID MCNAIR: The team tried to understand as to why the crew

continued to the north.

What cues could they have got,

and why did they ignore those cues?

DAVID ROHRER: Take a look at this.

There are no cardinal points on the compass.

NARRATOR: A close look at the cockpit compass

reveals a possible explanation.

The instrument lacks the usual direction markers, N, S, E, W,

for North, South, East and West.

DAVID MCNAIR: It had just numbers.

I think if there had been a big N on top of the compass

the whole time it might have made a difference.

JOHN: When you're fully confident about where you're going,

at what altitude, in what direction,

when you think you have the mental picture,

but yet you don't actually have the mental picture,

you're situationally unaware of where you are.

DAVID ROHRER: You know, one thing still bugs me though.

Why didn't the controller figure out where the plane was?

NARRATOR: Just over three minutes before impact, the controller

asks the captain for their distance from the airport.

AIR TRAFFIC CONTROLLER: Thai 311, go ahead your DME for Kathmandu.

CAPT. SUTTIMAI: We are five DME from Kathmandu.

NARRATOR: The captain reports that he's five miles away.

JIM: The reported distance by the pilots

just didn't make any sense to the controller.

NARRATOR: It's been five minutes since the Thai captain

reported turning back toward Romeo.

If he's flying south, away from the airport,

he should be about 25 miles away, not five.

JOHN: The controller can't see on his screen

where this airplane's going.

All he can do is have a picture in his mind

that the airplane is here and it's still following a script.

But guess what? The airplane's no longer following that script.

AIR TRAFFIC CONTROLLER: Confirm, two-five DME?

CAPT. SUTTIMAI: Five. Zero-five.

JIM: The pilot, when the controller asked him about that,

very firmly said, "Five, zero-five,"

and I think that had the effect

of shutting down an inexperienced controller...

AIR TRAFFIC CONTROLLER: Roger. Report over Romeo.

JIM: ... and forcing him to not probe deeper

and ask any further questions.

And that's a real shame because I think in this event

it might have made all the difference in the world.

FO. BOONYAYEJ: Are we going north?

CAPT. SUTTIMAI: We will turn back soon.

JOHN: And then only many miles north of the airport

at some point does the first officer say,

"Hey, my display says I'm north of the airport."

And he looks over, and he says to the captain, he says,

"We're north of the airport." But by then it's too late.

GPWS: Terrain. Terrain. Pull up.

FO. BOONYAYEJ: Turn back. Turn back!

CAPT. SUTTIMAI: It's false. It's false.

DAVID ROHRER: He's totally locked into being in another place

and nothing that the first officer was gonna say

was gonna change his perception of where he was.

♪ ♪

♪ ♪

JIM: It's an amazing thing how powerful our minds are sometimes

when we're convinced we're doing something,

even if that something is totally wrong.

NARRATOR: The crash of Flight 311 underscored the need

for more advanced air traffic control technology

at Nepal's Tribhuvan Airport.

DAVID ROHRER: In an environment like Kathmandu, radar was essential.

And radar was put into Kathmandu

so this would not happen again.

NARRATOR: The Thai Airways disaster also drove home

the crucial importance of teamwork among pilots.

A fundamental rule requiring a division of duties

in the cockpit must never be ignored.

JOHN: It's not easy to realize, yeah, I'm so overloaded.

I have to start delegating tasks.

I have to stop doing everybody's job.

He was trying to do everybody's job.

At some point you have to say, enough is enough.

I'll fly the airplane.

You handle the communication and tell ATC what I am doing.

Tell them.