Original subtitles

[jet engine]

FLIGHT ATTENDANT: Ladies and gentlemen,

we're beginning our descent towards Amsterdam's Schiphol

Airport.

[non-english speech]

Thank you.

NARRATOR: Turkish Airlines Flight 1951 is

preparing to land in Amsterdam.

Amsterdam, Turkish 1951, descending to 7,000, speed 250.

[beeping]

NARRATOR: The crew is flying a state of the art Boeing 737.

Flaps 15.

PILOT: Localizer are live.

Localizer capture.

NARRATOR: In the final moments of the flight,

the landing turns into a catastrophe.

The plane falls like a rock.

The crash of Turkish Airlines Flight 1951

involves the most popular plane on Earth.

With nearly 1 and 1/2 million passengers boarding 737 sevens

every day--

[screaming]

--investigators need to figure out

if the problem was with the plane

or with the pilots flying it.

FLIGHT ATTENDANT: Ladies and gentlemen,

we are starting our approach.

PILOT: We lost both engines.

FLIGHT ATTENDANT: [inaudible] emergency descent.

PILOT: Mayday, mayday.

CHILD: We're going to die.

[explosion]

PILOT: This will be the last one.

REPORTER: The investigation started when [inaudible]..

MAN: It's going to crash.

[somber music playing]

NARRATOR: On the morning of February 25, 2009,

Turkish Airlines Flight 1951 becomes the first plane

to crash at Amsterdam's Schiphol Airport in more than 10 years.

[non-english speech]

INTERPRETER: It smashed into the ground really hard.

It made a tremendous noise.

[crash]

NARRATOR: The plane hits the ground in a muddy field

just North of Runway 18 Right.

[sirens]

Since the crash was so close to the airport,

rescue workers arrived quickly.

Most of the passengers have survived.

But many are badly injured.

Survivors are taken straight to local hospitals.

Images of the Amsterdam accident quickly

spread around the world.

This is the third crash of a passenger

jet in the past six weeks.

The sudden nature of this accident adds to the mystery.

[inaudible speech over radio]

It doesn't take long for the Dutch Safety Board

to arrive at the scene.

They will be investigating this accident.

But they won't be alone.

The crash involved an American-made plane.

So the US National Transportation Safety Board

sends Joe Sedor, one of its most experienced investigators,

to Amsterdam.

JOSEPH SEDOR: When it's a non-US registered aircraft that

crashes overseas, such as this Turkish Airlines,

we are the state of manufacture and design of the air frame

and also, in this case, the engines.

Fuselage in three large pieces.

Engines forward of the main wreck site.

NARRATOR: Flight 1951 was one of the most

advanced aircraft in the skies, The Boeing 737 800 Series.

It's designed to travel longer routes at higher altitudes.

The new generation 737 is still the best airplane Boeing

ever built. We developed an airplane that had an improved

wing, improved avionics, simpler systems

that required less maintenance.

NARRATOR: Investigators know this isn't just any plane.

The 737 is the world's best-selling commercial jet.

Finding out why this one crashed is imperative.

There are more than 5,000 of them in the skies.

They carry about 1 and 1/2 million passengers a day.

Investigators must quickly determine

if there's a flaw with the plane that

could cause another accident.

What they know so far is that flight

1951 had been traveling from Istanbul, Turkey to Amsterdam.

There were 128 passengers on board the early-morning flight,

including four engineers from Boeing.

FLIGHT ATTENDANT: Ladies and gentlemen,

we're beginning our descent towards Amsterdam's Schiphol

Airport.

Please raised your seat backs to the upright position

and stow away your tray tables.

NARRATOR: There was no mention on board of any kind

of trouble in the cockpit.

The crash has killed nine people, including

three members of the Boeing team and the pilots in the cockpit.

See if you can get me some aerials of the crash site.

NARRATOR: There are eerie similarities

to another recent accident involving a Boeing aircraft,

British Airways Flight 38.

JOSEPH SEDOR: Approximately a year before this,

there had been Triple Seven short landing

at Heathrow, which had a dual-engine flame out.

NARRATOR: In that accident, a Boeing Triple Seven

fell to the ground, short of the runway.

The British Airways pilots reported

that both their engines stopped delivering

power just before landing.

At the time of the Turkish Airways crash,

the cause of that accident hasn't been found.

As in that case, investigators have

plenty of clues to work with.

The plane and its engines are largely intact.

The flight-data recorder and cockpit voice recorder

are found in good condition.

There are also plenty of survivors

to describe what happened.

According to the passengers, the landing had been routine.

But then suddenly, the plane simply dropped out of the sky

and hit the ground.

[crash]

But perhaps the biggest clue comes

from the crash site itself.

The wreckage is not spread out.

It tells investigators that the plane could not

have been traveling forward at high speed

when it hit the ground.

JOHN NANCE: The way the aircraft had crashed,

it did appear to be some sort of a landing accident

in which there was moderate control of some sort.

NARRATOR: The pattern of debris and the passenger

reports point investigators to an immediate suspect,

the engines.

The engines issue was a very big issue in my thought process

at the time, initially.

NARRATOR: There's no evidence of fire on the fuselage.

In many crashes, fuel in the plane's tanks

ignites on impact.

The lack of fire raises an obvious question.

Did the engine stop running because flight

1951 had simply run out of gas?

JOHN NANCE: That was one of the first thoughts that I had was,

did this airplane have fuel aboard?

Because otherwise, how does a 737

literally fall out of the sky on approach to an airport?

NARRATOR: But the location and condition

of the plane's engines suggest that perhaps

they didn't quit in flight.

JOSEPH SEDOR: Sure it looks like it was running.

When we first looked at where the engines ended up,

the initial impression was that they probably were producing

thrust at impact, given that they were so far

forward of the main wreckage.

But that was just a very general conclusion.

NARRATOR: Only the flight-data recorder can tell investigators

how much power the engines were generating in the seconds

before the crash.

It had lots of fuel.

Rules that out.

NARRATOR: It doesn't take long to discover

that there is plenty of fuel in the plane's tanks.

Flight 1951 definitely did not run out of gas.

Passengers report that in the final seconds before the crash,

the plane hit what felt like turbulence.

It points investigators to a well-known culprit,

a micro burst.

A micro burst is a powerful column of air that

shoots out of storm clouds.

It can literally slam a low-flying plane to the ground.

JOHN NANCE: If an airplane flies into that at approach speeds,

you're not going to be flying anymore.

You're going to come out of the sky.

Certainly, it was one of the things that all of us

took a look at, at the beginning,

was there a micro burst?

[crash]

NARRATOR: In 1985, a Delta Airlines flight

was caught in a micro burst while landing

at Dallas-Fort Worth Airport.

The plane hit the ground short of the runway.

137 people were killed.

Investigators learned that there were

heavy clouds above the airport at the time of the accident.

A powerful gust of wind may well have accompanied them.

The flight-data recorder will have recorded

wind speeds outside the plane.

Investigators will need to analyze

the flight data to prove the micro-burst theory.

In the meantime, the rescue has led to an unusual discovery.

JOSEPH SEDOR: There was three pilots in the cockpit

which is unusual.

This is a two-crew cockpit.

So why was that third pilot there?

NARRATOR: Since none of the three pilots

survived the accident, it's all the more

urgent for investigators to retrieve

the data from the cockpit voice recorder.

It records conversations in the cockpit.

They're in luck.

JOSEPH SEDOR: Because of the way that the aircraft crashed,

access to the recorders and the condition of the recorders

was excellent.

NARRATOR: The reason for the third pilot is soon uncovered.

Flying standard arrival route.

Visibility, 3,500 meters, expected

to decrease to 2,500 meters.

NARRATOR: For first officer, Murat Sezer

this has been a training flight of sorts.

He was new to the airlines and was

being shown the intricacies of landing at Amsterdam's airport.

BILL HUFF: When the Jeppesen charts,

which is what all pilots use to navigate to and from Schiphol,

there's 102 pages of information on Schiphol alone.

So there's dozens of approaches.

Runway 18 right has three high-speed exits to the left.

NARRATOR: The captain, Hasan Arisen was doing double duty.

He was training his first officer--

Make small corrections as we get close to the runway.

NARRATOR: --and was in command of flight 1951.

It's because captain Arisen was teaching that there was

the third pilot in the cockpit.

Olgay Ozgur was a safety pilot.

He was there to keep an eye on the flight's progress

during this training mission.

JOSEPH SEDOR: The purpose of that second set of eyes

is to make sure that the captain and the first officer,

if they're in a situation where it's

a little bit of a training portion of the flight,

that they don't miss something.

We've got a clean recording?

NARRATOR: The voice recorder reveals that the three crew

members began preparations for landing

when still above 8,500 feet.

Amsterdam, Turkish 1951, descending to 7,000.

Speed, 250.

[beeping]

NARRATOR: But the voice recorder has picked up

an unusual sound, a warning that makes no sense

at this stage of the flight.

One of the investigators from Boeing

was a engineering pilot that came and helped with the CVR.

And he's listening to see when--

are there any unusual sounds that can be

heard that would not be normal.

AIR TRAFFIC CONTROLLER (OVER RADIO):

Speed OK for ILS 18 Right.

PILOT: Descend 4,000, ILS 18 Right.

NARRATOR: The alarm keeps sounding.

It's the landing-gear-configuration

warning horn.

Captain Arisen continually dismisses it.

Turkish 1951, dissent 4,000, ILS 18 Right.

Landing gear.

Is that the landing-gear warning?

They're 8,300 feet here.

NARRATOR: The warning is a solid clue.

But investigators can't yet see how it could

possibly have caused a crash.

got warnings to extend their landing gear while still

thousands of feet in the air.

JOSEPH SEDOR: On the initial listen,

we heard a gear warning horn occur

as the aircraft was approaching, when it was still up.

And it was coming in at about 10,000 feet and below.

NARRATOR: Investigators now turn to the flight-data recorder

to help solve some of the mystery

surrounding this flight.

The analysis of wind speeds outside the aircraft

is completed.

It's clear.

None are drastic enough to have brought down the plane.

There's no evidence of a micro burst.

NARRATOR: But the flight-data recorder

does provide some valuable insight into the cause

of the landing-gear warning.

One of the instruments that measures altitude

had the plane already on the ground.

JOSEPH SEDOR: When we looked and saw

the radio altimeter data on the recorder,

it said about 8,000 feet.

And then immediately, it went down to about minus 8.

Minus 8 feet is an indication that the aircraft's

on the ground.

But of course, it's still at 2000 feet.

NARRATOR: The Boeing 737 is equipped

with two separate altimeters.

One measures air pressure to determine the plane's

height above sea level.

That reading is displayed prominently in the cockpit

on both pilots' flight display.

PILOT: 210, sensor.

NARRATOR: The plane is also equipped with a radio

altimeter.

It's made up of four antennas.

Two transmit signals to the ground and two others

read the signal that bounces back to determine

the plane's altitude.

It's precise.

It's very, very precise.

Pressure altimeters can sometimes be not as accurate.

And radar altimeters are 100% accurate

if they're working properly.

[jet engine]

NARRATOR: One antenna feeds the reading

to the first officer's display.

The other feeds the captain's instruments.

In the case of Flight 1951, the captain's side

was wrong most of the flight.

Investigators go back over the CVR

and make a puzzling discovery.

PILOT (OVER RADIO): Amsterdam Turkish 1951

descending to 7,000, speed 250.

Radio altimeter.

NARRATOR: Captain Arisen seems to have known

that the landing-gear warning was being caused

by a faulty radio altimeter.

The airplane thought that it was low to the ground

and the gear was not down.

And the captain recognized that the problem was really

in the radio altimeter, showing him that they

should be on the ground.

And he goes, it's just the radio altimeter.

NARRATOR: Throughout much of the approach,

the captain's radio altimeter had been displaying

a reading of minus 8 feet, triggering

the warning to lower the gear.

They treated it like it was a nuisance.

AIR TRAFFIC CONTROLLER (OVER RADIO):

Turkish 1951, descend to 2,000.

2,000, 1,951.

NARRATOR: Investigators dig for any other abnormalities.

They learn that with Flight 1951 a little over 10 miles

from the airport, controllers directed

the pilots to begin their final turn

to line up with the runway.

Turkish 1951, left heading.

210, cleared approach.

18 right.

Left 210, clear ILS, Turkish 1951.

COPILOT: 210 set, Sir.

NARRATOR: This turn puts Flight 1951 in line

with Runway 18 Right.

It's equipped with an instrument landing system which sends

out a signal, outlining the ideal descent

path to the foot of the runway.

The autopilot follows that glide path

until the plane is a few hundred feet from the ground.

Then the pilot takes over.

It makes landing almost effortless.

The ILS is pretty easy to follow.

It's a video game.

NARRATOR: The crew begins configuring their plane

for landing, unfazed by the warning

horn that's repeatedly triggered by the malfunctioning radio

altimeter.

Flaps 15.

NARRATOR: Six miles out, Flight 1951

picks up the ILS signal that will

guide the plane to the runway.

Localizer are live.

Localizer capture.

NARRATOR: The safety pilot, Olgay Ozgur,

now reminds captain Arisen about the failed altimeter.

We have radio altimeter failure, Sir.

OK.

AIR TRAFFIC CONTROLLER (OVER RADIO):

Turkish 1951, Runway 18 Right, clear to land.

Cleared to land.

Thank you.

NARRATOR: Investigators are stumped.

The crew knew about the malfunction

and continued their approach.

How had it then caused them to crash?

Clearly, there was more to this accident

than a faulty altimeter.

JOHN NANCE: The whole premise of airline safety, the way

we build the airplanes, the way we fly them,

is based on the idea that we can have any number of failures

and we should still be able to arrive safely.

The radio altimeter is just one instrument.

There's no way in the world that that one instrument, if it

fails, should be a major cause of worry

that we're going to have a crash.

NARRATOR: Investigators wonder if the crew

had been given proper guidance for their approach.

They turn to exchanges between the pilots

and the controller who guided them in.

They carefully review every instruction.

AIR TRAFFIC CONTROLLER (OVER RADIO): Turkish 1951,

send to 4,000.

Speed OK for ILS 18 Right.

Turkish 1951, descend to 2,000.

Turkish 1951, left heading, 210, cleared approach.

18 Right.

NARRATOR: By following the controller's instructions,

the crew made their final turn much too close to the runway.

So they intercept properly, they should be here.

NARRATOR: International guidelines call for approaching

planes to intercept the signal that guides them to the runway

from below.

It's so pilots don't have to make

any drastic, last-minute course corrections to get to it.

To intercept here, they had to descend.

NARRATOR: But flight 1951 was given instructions that brought

it to the threshold of the glide slope while still way above it.

It's a common practice at Schiphol

because it gets planes to the runway faster.

JOSEPH SEDOR: Because they were so close,

they had to capture the glide slope from above.

Although it is an unusual situation,

it is one that that can be handled by a flight crew

if it is managed properly.

NARRATOR: Approaching a glide slope from above

is more difficult, mostly because the crew has

to suddenly slow the plane and descend rapidly

to intercept the signal.

BILL HUFF: We also call this a slam-dunk approach.

And some pilots like it.

Some pilots don't.

It's a little bit harder.

And things happen quicker when you're above the glide path,

trying to intercept from above.

And it's just a challenge for a lot of pilots.

NARRATOR: The approach from above

increased the crew's workload.

But it's standard practice at Schiphol airport.

I've flown in to skip over dozens of times.

And I expect it.

NARRATOR: If the controller's instructions

had somehow overtaxed this crew, their conversations

would indicate it.

They're just three miles from the runway.

PILOT: 1,000.

Check.

PILOT: Flaps, 40.

Speed brake?

COPILOT: Speed brake armed.

Green light.

One thing at a time.

Landing gear?

COPILOT: Gear down.

Three green.

PILOT: Flaps?

Flaps 40.

Green light.

PILOT: 500.

All lights on.

Please warn the cabin crew.

Cabin crew, take your seats.

[beeping]

NARRATOR: Then, real trouble, a stall warning.

COPILOT: Speed, Sir.

I have control.

100 knots of speed.

NARRATOR: Arisen fought to save his plane.

But just 400 feet above the ground and less than a

mile from the runway, the Boeing 737

suddenly fell straight down.

It only took a few seconds for it to hit the ground.

[muffled screams]

[crash]

NARRATOR: The CVR recording sheds

light on the final minutes of Turkish Airlines Flight 1951.

The crew was configuring their plane for landing well

after it should have been done.

Flaps 40.

Green light.

NARRATOR: Most airlines have regulations that

call for a flight to be stabilized,

to have all checklists completed by the time

the plane hits 1,000 feet.

In instrument conditions, you required a 1,000 feet to have,

basically, everything done.

The airplane is configured.

You have slowed.

You have run your before-landing check.

And you have received your landing clearance.

And from 1,000 feet on in, you just monitor the instruments

and were looking for the runway.

Please warn the cabin crew.

Cabin crew--

NARRATOR: In fact, this crew was still running their checklist

up to the moment the crisis hit, 460 feet above the ground.

This approach was not stabilized.

JOSEPH SEDOR: And because the aircraft was unstable,

the flight crew was in a very high-workload environment in

the last 1,000 feet of flight.

NARRATOR: The radio altimeter was malfunctioning.

The aircraft was giving off warnings.

The crew was assigned a challenging approach.

And they were executing a checklist late.

But none of this explains why Flight 1951 crashed.

In these type of accidents, you can never get

inside the head of the pilots.

And that's a very frustrating type of accident.

NARRATOR: But the flight-data recorder does provide

another intriguing clue.

Moments before Flight 1951 hit the ground, the plane's engines

were at idle, hardly providing any power.

Perhaps this accident is a repeat

of the Heathrow incident.

JOSEPH SEDOR: The engines, it was interesting to note,

were at idle approximately the last two minutes of flight,

until the very end, when the thrust was increased again.

That was a big red flag right there.

The question is is, why was that the case?

NARRATOR: But then they spot something

that's very different from the accident at Heathrow.

Retard-flare mode.

NARRATOR: For some reason, while still more than 1,000 feet

above the ground, the plane's computer

began preparing to touch down.

In retard-flare mode, engine power is reduced

to idle by the flight computer.

And the plane's nose automatically pitches up

to the flare position.

Planes should only be in this configuration

just before they touch the ground.

The autopilot raises the nose to break the descent.

The auto throttles brings the power back to flight idle.

And you touch down with the power

either all the way in idle or just about to be in idle.

NARRATOR: But Flight 1951 went into a slow, nose-up position

well before touchdown, causing the plane

to fly slower and slower throughout its descent.

Speed, Sir.

NARRATOR: So why was Flight 1951 in landing mode?

COPILOT: [inaudible] loss of speed.

NARRATOR: And why hadn't any of the three crew members

noticed how slowly they were flying?

[crash]

[screaming]

So what else was going on when the engines went to idle?

NARRATOR: The trouble seems to start with the malfunctioning

altimeter.

JOSEPH SEDOR: We had to look at the system as a whole

and to see how that minus 8 affected the other systems

on the aircraft.

And that was a very big portion of this investigation.

We had to say, how did the autopilot use that data?

More importantly, how did the auto throttle use that data?

NARRATOR: The computer that flies

the plane consists of two main systems, the autopilot

and the auto throttle.

The auto throttle determines how much power to ask the engines

for while the autopilot controls the plane's

altitude and direction.

The two systems work independently

of each other and only one of the radio altimeters

provides information to the auto throttle.

In this case, I had to learn everything there was

about radio altimeters and auto throttle systems,

which I didn't know before.

NARRATOR: The pieces of the puzzle

begin coming together when they find

the connection between the faulty radio

altimeter and engine power.

The radio altimeter provides information

to the auto throttle from the captain's side.

NARRATOR: The only altimeter feeding information to the auto

throttle was the captain's.

And it was wrong.

It showed minus 8 feet throughout most

of Flight 1951's approach.

It's beginning to look like the faulty radio

altimeter triggered the events that led to the crash.

Investigators need to know what went wrong with it.

On a 737, the transmitting and receiving antennas

for both radio altimeters are lined up

underneath the cockpit.

Three of the antennas were all but destroyed in the crash.

They can't be tested.

But one antenna from the captain's side is undamaged.

Investigators consider two possibilities, a failure of one

of the components or some sort of interference

that caused the faulty reading.

The only component that survived the crash checks out.

The computers that control the system also work.

But investigators do make a curious discovery about them.

They aren't the same ones that were installed

on the plane when it was delivered to Turkish Airlines

seven years ago.

This find changes the focus of the investigation.

JOSEPH SEDOR: The maintenance aspect

of this accident aircraft was one that we looked

at as deeply as we could.

NARRATOR: When the plane's maintenance log is studied,

investigators find that the radio altimeter on this plane

had a problematic history.

JOSEPH SEDOR: We got additional data from Turkish airlines.

And that data showed that, on this one aircraft, of the past,

I believe, over 1,000 flights, there

was about 150 flights that had faulty radio-altimeter systems.

NARRATOR: The documents show that a little more than a year

before the crash, both computers were

replaced because of complaints they

were causing faulty readings.

One of the incidents involved a radio-altimeter reading

of minus 8 feet.

[beeping]

JOSEPH SEDOR: So that was telling us that there was

an issue that had been there.

The issue did not just occur on this flight.

NARRATOR: The faulty readings persisted.

Mechanics repeatedly swap the computers

and replace the antennas to try to solve the problem.

It's determined that Turkish Airlines tried several ways

to fix the altimeter.

But they couldn't find a repair that worked.

At the time of the accident, Turkish airlines

had a fleet of 52 Boeing 737 800-series airplanes.

JOSEPH SEDOR: It's on page 93.

When we reviewed the maintenance data,

we found that radio-altimeter problems had been

written up several times on both the Axon airplane

and the fleet.

NARRATOR: Investigators discover that in the year

before the crash, Turkish Airlines

dealt with 235 system faults with the radio

altimeters on their 737s.

Fixes ranged from Replacing and exchanging antennas, cleaning

of the systems, exchanging and replacing the computers,

and installing gaskets to shield the system

from possible water damage.

It's not like they weren't doing anything about it.

JOSEPH SEDOR: The Turkish Airlines maintenance personnel

knew that the radio-altimeter problem

was one of their highest issues with regard to maintenance.

NARRATOR: 16 of those altimeter repairs

were made to the plane that crashed in February, 2009.

If the problem was so widespread,

investigators wonder why it hadn't caused serious problems

before this accident.

They don't have to dig too far back

to find out that, in fact, it had, on this very same plane.

On two recent flights, they had the exact same problem.

NARRATOR: Twice, in the 48 hours leading up to the accident,

the radio altimeter showed a negative reading,

putting the plane into retard-flare mode.

Both times, the crew noticed the problem,

disengaged the auto throttles, and brought the plane

in for a safe landing.

You just disconnect it and fly the airplane.

NARRATOR: In the months after the crash,

other operators came forward with similar stories.

In Australia, in the Netherlands,

in Canada, in Austria, pilots report their 737s

going into retard-flare mode when the left radio altimeter

showed a faulty reading.

Each of those crews reacted the same way.

They disengaged the auto throttle and pushed

the power back up manually.

They all landed safely.

BILL HUFF: Things are going to break on an airplane.

And usually, you're able to identify that and take

that out of-- make it so that it's

not a threat for the landing.

NARRATOR: In 2008, Boeing received

a whopping 2,569 reports of faulty radio altimeters

on their latest 737s.

But very few of those cases involve the plane

going into retard-flare mode.

Hardly any reports at all.

NARRATOR: Boeing also tried, but couldn't

find the cause of the failures.

They concluded that the radio-altimeter problem was not

a threat to safety because the 737 gives

off enough warnings so that crews

can intervene and land safely.

In fact, in every instance where the radio altimeter failed,

crews were able to recover.

Turkish Airlines Flight 1951 seems to be the one exception.

Investigators still don't know why.

It really got us wondering of what happened.

And that's when we started to look really closely

at the actions of the flight crews

while it was on that final approach,

in less than 1,000 feet.

of Turkish Airlines Flight 1951, the circumstances

of the tragedy become clear.

They see a remarkable sequence of events that transpire

to bring down this plane.

So what was happening when the plane

went into retard-flare mode?

NARRATOR: They discover that the plane went into landing mode

and pulled back power at the worst possible moment,

exactly as the crew was descending

to meet the glide slope.

It masked what was actually happening.

NARRATOR: As the crew configured their plane to drop down

to meet the glide slope, they expected the plane to slow

down as part of that maneuver.

But the plane was actually slowing down

because the computer was in landing mode.

That's why none of the three pilots

said anything about the throttles moving to idle.

BILL HUFF: It was insidious.

Where it first captured in the retard mode,

it didn't hurt them at all because they were actually high

and they were a little bit fast.

And the pilots actually wanted the power back anyway.

In fact, the throttles may have already

been in the flight-idle mode as they were trying

to get down and slow down.

All right, the trouble starts here, at 8,300 feet,

13 miles out from the airport, minutes before the crash.

PILOT: Amsterdam, Turkish 1951, descending 7,000, speed 250.

AIR TRAFFIC CONTROLLER (OVER RADIO):

Turkish 1951, descend to 4,000.

Speed OK for ILS 18 Right.

[beeping]

Radio altimeter.

JOSEPH SEDOR: Would the crew have known

that, because of that radio altimeter,

they would have gone to a retard-flare mode

in the throttles?

No.

It was a common problem at the airline.

But the crew couldn't see the risk it posed this flight.

We have an airplane that was malfunctioning in a very minor

way, but in a way that, if not caught,

could and did metastasize into something much more virulent.

AIR TRAFFIC CONTROLLER (OVER RADIO):

Turkish m descend send to 2,000.

2,000, 1951.

AIR TRAFFIC CONTROLLER (OVER RADIO):

Turkish 1951, left heading 210, cleared approach.

18 Right.

Left 210 clear ILS, Turkish 1951.

EXPERT: It left at 210 degrees, maintaining 2,000 feet,

brings the flight in right here, 5.5 miles out.

They now have to intercept the glide slope from above.

NARRATOR: At 2,000 feet, with the glide slope below them,

the pilots have to reduce their speed while descending steeply.

Speed, 140.

NARRATOR: They believe the throttles are moving back for

the descent to the glide slope.

In fact, the auto throttle is slowing the plane down because

it's gone into landing mode.

It will continue to slow the plane until it stalls.

JOSEPH SEDOR: What we found is that, when the flight crew was

doing their before-landing checklist, each one of them

was doing something while they should have

been monitoring their airspeed.

For the next 100 seconds, no one notices what's happening

'til it's too late.

COPILOT: Established altitude set.

PILOT: 1,000?

COPILOT: Check.

PILOT: Flaps 40.

Speed set.

The experienced pilot recognized

that the first officer was probably a little bit

behind on the approach.

So he calls for flap 40 and moves the lever,

informing the first officer that he has done so.

He's trying to help the first officer catch up

to the position of the aircraft.

PILOT: Speed break?

COPILOT: Speed brake armed.

Green light.

PILOT: One thing at the time.

Landing gear.

NARRATOR: The plane is now 700 feet from the ground.

COPILOT: Gear down, three green.

PILOT: Flaps?

COPILOT: Flaps 40, green light.

NARRATOR: In their haste to complete their checklist,

none of the three crew members noticed

the warnings that their speed is dropping dangerously.

First, a red bar appeared on their flight display.

[beeping]

Then, when the air speed continued to drop,

a flashing box appeared around their actual airspeed

to draw the pilot's attention to it.

At this point, no one sees either.

COPILOT: Cabin report confirmed.

NARRATOR: The aircraft is now 600 feet from landing.

When things start changing colors, it's a warning to you.

It's a caution to you that you're approaching

the limits of the aircraft.

PILOT: Missed approach.

Altitude set.

500.

JOSEPH SEDOR: So all of these indications

the crew has in front of them, saying that the aircraft is

slowing down, during that time, they were still

completing their checklist.

BILL HUFF: Of course, the aircraft is

getting closer to the ground.

NARRATOR: In fact, it's less than 500 feet from touchdown.

And right before the stick shaker

started, the captain told the safety pilot--

PILOT: Please warn the cabin crew.

SAFETY PILOT: Cabin crew, take your seats.

COPILOT: Speed, Sir.

PILOT: I have control.

BILL HUFF: By the time they advanced the throttles

to full power, it was unrecoverable.

They were too low for the engines to catch up.

And that's it.

It's now too late to save this plane.

[crash]

They all knew about the altimeter problem

but knowing didn't help.

of a faulty altimeter.

But on February 25, 2009, it triggered an unusual sequence

of events that brought down a jetliner

and killed nine people.

The official report into the accident

blames it on a convergence of circumstances.

JOHN NANCE: There is never, ever just one

cause to an airline accident.

It simply doesn't exist.

Maybe someday, God will slap one out of the sky.

But until then, there's never one cause.

NARRATOR: The Dutch report also points out that Boeing could

have realized that the problem with the radio altimeter system

could have had an impact on safety.

Given that no one foresaw how that failure might

cause a crash, the Turkish Airlines

accident raises a big question.

Are airplanes becoming too complex?

Investigators have determined the Turkish Airlines Flight

1951 crashed mainly because the pilots

didn't recognize the consequences of the warnings

they were getting.

AIR TRAFFIC CONTROLLER (OVER RADIO): Turkish 1951,

descend to 4,000--

NARRATOR: This is not the first plane

to crash because the crew didn't understand what

their plane was telling them.

JOHN NANCE: Our problem is not the automation.

Our problem is the depth of the training and the ability

of the human beings to recover from mistakes

made in interfacing with the automation.

NARRATOR: Mica Endsley studies the relationship

between pilots and technology.

MICA ENDSLEY: And we haven't really designed the automation

to take best advantage of what people do well

and take them take away the parts

that people don't do well.

NARRATOR: In 1996, the crew of an Aeroperú 757 crashed when

the pilots couldn't decipher contradictory warnings about

their altitude and airspeed.

The plane flew into the Pacific Ocean.

61 passengers and 9 crew members were killed.

In 1995, the flight management system on a Boeing 757

could and should have steered the plane to a safe landing

in Cali, Colombia.

But a last minute change to the flight plan

meant the crew had to reprogram their computer.

They mistakenly entered a course that took them headlong

into a 9,000-foot mountain.

159 people died in the crash.

JOHN NANCE: The cautionary tale here is

that we can get this equipment.

We can get these silicon-based units, if you will,

so sophisticated that we can't talk to them, effectively.

And when they go berserk or they have a problem

or we misprogramed them, we end up

putting ourselves and our passengers in danger

while we're trying to figure out.

NARRATOR: What some researchers are finding

is that the best technology shouldn't replace pilots,

but work with them.

MICA ENDSLEY: Really, integrating people

with technology more effectively has to do with designing

the displays so that you can't really understand what it's

doing, and you can make it simpler

to understand how to make it do what it is you want it to do.

You shouldn't have to push 16 buttons

through 8 levels of menus to figure out what's

going on with the system.

It should be integrated and presented effectively.

It should be as easy to communicate

with as the person next to you.

NARRATOR: Boeing and Airbus, the two largest manufacturers

of passenger planes, take very different

approaches to the relationship between humans and technology.

Airbus gives the flight computer much

of the decision-making power in the cockpit.

In their view, this is a way to prevent

a lot of human errors, by making sure the airplane doesn't do

something it's going to cause a crash,

even if the humans want them to.

NARRATOR: But Boeing has a different view.

Its philosophy is to provide information to pilots

and have them make decisions.

Having more information is better

for the pilot, having the pilot in the loop, in the equation,

so to speak.

I kind of like that.

Airbus will argue vociferously,

and in continuous fashion, that that view

is archaic and incorrect.

I think the jury is still out.

NARRATOR: The final report into the Turkish Airlines tragedy

blames the crash of Flight 1951 partly

on a failure of technology.

JOSEPH SEDOR: The erroneous radio-altimeter data

caused the auto throttle to go to a improper mode that is,

of course, not a good situation.

NARRATOR: The Dutch investigation

asks Boeing to improve the reliability of the system.

JOSEPH SEDOR: We learned a lot about

the radio-altimeter system and how it affects

the auto throttle system.

NARRATOR: Boeing ultimately changed the throttle system

so that one erroneous altitude reading would never again

trigger a similar tragedy.

But the report also faults the crew

for not noticing that their airspeed was dropping

dangerously low, in spite of the fact that there

were three pilots on board.

GORDON BETHUNE: Forget that you got an auto throttle.

You look at the airspeed.

And you look at the altitude.

You look out the damn window if you want to.

But airspeed is a crucial component of staying alive

in an airplane.

And you always need to know what your airspeed is.

NARRATOR: But to Mica Endsley, the crew's failure

to monitor instruments is entirely understandable

and may be more the fault of the instruments than the crew.

MICA ENDSLEY: It's actually very difficult for people

to be monitors of automation.

One of the things that people don't do a good job of,

actually, is monitoring.

We're very good on-the-spot decision makers.

We're very good at coming up with creative solutions

to problems.

But repetitive monitoring is the kind of thing

that actually, people aren't very good at at all.

So what we have to do is design automation to work with people

in a way that keeps them more actively, cognitively involved

and in the loop, and not just monitoring

a piece of automation to say, is it doing

what it's supposed to be doing?

JOHN NANCE: Who's the ultimate computer?

The pilot, the individual who should be able to say,

I don't know what this thing is doing to me

but I'm punching it off and flying the airplane.

Fly the jet.

Probably the smartest thing we ever learned to say,

in our training in the airlines, fly the jet.

Do that first or nothing else counts.

That's what they forgot to do.