Air Emergency (2003–…): Season 4, Episode 5 - Hidden Danger - full transcript
The Boeing 737 is one of the most popular
passenger jets in the world
Around the globe the plane has carried
more than 12 billion passengers
It is the backbone of the aviation industry
But in 1991, something happened on-board a 737
that send shatters through the world of aviation
Oh, my Lord
A deadly crash as investigators scrambling
There was a time when I dealt
to be able to solve it
It was like he was tracking a serial killer
The hunt for answers will take
10 long and gruelling years
The fate of the airline industry
hangs in the balance
and the mystery isn't solved
until more than a 150 people...
...are dead
This is a true story
It is based on official reports
and eyewitness accounts
Air Crash Investigation Season 04
Hidden danger
09:40 AM
March 3rd 1991
After a short 17 minute trip from Denver,
United Airlines Flight 585 is on
final approach on Colorado Springs
It looks like a perfect day for flying
but there is trouble in the air.
Nice looking day,
Hard to believe the skies are unfriendly
There has been heavy turbulence during the flight
and violent gusts of wind
are forecast over Colorado Springs
They were driven to Colorado Springs
and then gotten sick
At the controls
is 52 year old captain Harold Green
a pilot with 20 years experience
and a sterling reputation
Green's copilot is Patricia Eidson
At 42, she is one of the first female
flight officers in United Airlines' history
Flight attendants, prepare for landing?
At Colorado Springs Municipal Airport
Air Traffic Controller James Rayfield
is ready to bring Flight 585 in
United 585, report the airport in sight
You got it?
Airport in sight, United 585
Lower landing gear
United 585 is cleared for a visual approach
to runway 35
Weather conditions:
Wind 320 degrees at 16 gusts to 29
As its speed decreases,
Flight 585 becomes more
vulnerable to the turbulence
Eidson wants to know
what other planes have experienced on landing
Any reports lately
of any loss or gain of airspeed?
Yes, ma'am
500 ft at 15 knot loss
at 400 ft a 15 knot gain
At 150 ft a gain of 20 knots
It sounds adventurous, thank you
Less than 3 km from the airport
a retired policeman, Howard Darnell
is on his way to a local flea market
A kilometre overhead,
Green and Eidson focus on keeping
their speed constant as they descend
Awful lot of power to hold that airspeed
As United 585 approaches the runway
Darnell feels something strange
What the heck was that?
Out of nowhere,
a powerful gust of wind strikes his
vehicle, almost blowing him off the road
Another 10 knot gain
30 flaps
From the control tower,
James Rayfield can now see
Flight 585's final approach
As the aircraft closes in on the airport
the ride gets even bumpier
Then, without warning,
the 737 starts to spin out of control.
Oh, my Lord
Crash, crash
Rescue workers arrive within minutes
but there is almost no sing of the 737
The shattered remains of the 38 tonnes jet
lie buried in a fire-blackened impact crater
The plane didn't bounce,
like when a plane normally comes and lands
It just went nose down
I came down here...
It was horrible
There are no survivors
All 20 passengers and 5 crew-members
are killed instantly
by the high-speed impact
and exploding jet fuel
In 10 violent seconds
Colorado Springs has become the site of
one of the most mysterious air-crashes
in aviation history
By nightfall, investigators from the NTSB
descend on Colorado Springs
Known to insiders as tin kickers,
NTSB investigators examine
over 2000 aviation accidents/year
at times by picking through the metal debris
of fallen aircraft
While coroners mark the location
of human remains in red
NTSB investigators mark scraps of metal in yellow
looking for clues to help them
solve the mystery of Flight 585
Like investigating a mass murder
it is a tough job walking onto a crash site
Among the investigators assigned to the case
is Malcolm Brenner
a specialist in human performance
His job will be to find out
if the crash was caused by pilot error
The area was cordoned off by police
and there were Salvation Army trucks
I got a cup of coffee, a cup of hot chocolate
or something
and I thank them for
and they said: No, no, thank you
and they had this look in their eyes like:
My God, you have to go into this site
Clues to the fate of the United 585
lie mangled in a deep black hole
The fuselage is crushed like an accordion
in the impact crater
The rest of the plane is in pieces,
spread over an area smaller than a football-field
There was a lot of fire-damage,
there have been a fire afterwards
and it was all contained
in a relatively small area
which, just an initial impression,
it can be a sign that the airplane was intact
If there was a mid-air explosion
or something came off the airplane
you'd expect that to be a much larger site
My first sense that it was going to take some time
in investigating the accident
was the damage that we saw
and the parts, they were burned and broken
the process always takes longer
But with their work just beginning
members of the NTSB have no clue
that the case of United 585
will become the longest crash investigation
in aviation history
A clear late winter-day in 1991
turned deadly in just 10 short seconds
Moments from landing in Colorado Springs,
United Flight 585 fell out of the sky at 370 km/hr
All 20 passengers and 5 crew-members died
The NTSB begins a painstaking investigation
into the crash
Engines turbines, hydraulic pressure gauges...
the CVR and the FDR
are all carefully extracted from the site,
photographed and sent to the lab for analysis
An important first step in the investigation
is the analysis of the CVR
With pilot error, a factor in 70% of air-disasters
Malcolm Brenner's job is to see what role
pilots Green and Eidson played in the crash
This crew was one of the more impressive crews
that I have ever dealt with
There is a little bit of tension release,
a little bit of humour
The captain said:
They were driven to Colorado Springs
and then gotten sick
The first officer suggested that they
added extra speed as a safety margin
The captain agreed with it ,
there was good interaction
Airport in sight United 585
Lower landing gear
This was the sense of an excellent crew...
...caught randomly, if anything
so again my first impression was
This would be consistent more
with a hardware situation
As more about Flight 585 becomes known
mechanical failure becomes a serious suspect
It appears increasingly likely
that the plane had suffered a catastrophic
problem with its flight controls
Investigators quickly become suspicious
of the rudder (at the back of the tail)
We focused in after eliminating
other flight control surfaces
that could contribute to the roll
We start looking at the rudder
Investigators begin their examination
of the rudder on site
but the violence of the crash
makes the job extremely difficult
most of the plane's parts
are too crushed or burned for testing
but a vital component is still reasonably intact:
The Power Control Unit or PCU
Used constantly during flight,
especially during landings
the PCU performs like a cars power steering
When the pilot pushes on the rudder pedal
the PCU uses hydraulic fluid
to convert gentle movements of a pilot's foot
into the pressure,
needed to move the 737's enormous rudder
The heart of the PCU is something
called the dual servo valve
Shaped like a soda can,
it has two slides which glide passed one another,
directing the flow of pressurized hydraulic fluid
that moves the rudder
The servo valve is very unique
that it is in effect two valves in one
and that creates a whole range of interactions
that don't occur
in a more conventional hydraulic valve
When a technician opens the Power Control Unit
chips of metal are found,
floating in the hydraulic fluid
It is a disturbing find
These particles could cause
the servo valve to jam,
making it impossible to work the rudder
It is a chilling prospect:
Could a microscopic fault
bring down a 38 tonnes jet?
It is difficult for Phillips to tell
While more intact than much rest of the wreck,
the PCU and dual servo valve are both damaged
The airplane crashed and burned
in a pretty confined area
and there was a lot of damage
to the flight control components
and the things we were testing
and needed to test and look at
The more damaged the components are
the harder it is to take measurements
and do functional testing
To test what he does have,
Phillips travels to California
to the labs of Parker Hannifin,
where the rudder control unit is made
The curious metal chips,
floating in the PCU's chambers, are dismissed
Phillips is told that filters keep
them out of the delicate servo valve
that directs fluid
and moves the rudder
Nothing else is found
that could explain any sudden
movement of the rudder on Flight 585
We didn't have any absolute indication
or information that we could point to
that said the rudder PCU, servo valve
or any part of that flight control system
caused that accident
With Phillips at a dead end
only bad mountain weather
remains as a primary suspect
An expert on weather related aviation accidents
Greg Salottollo is trying to determine if heavy
winds on the day of the crash were a factor
There is a history of events
where there have been airplane accidents
contributed to mountain waves or rotors
In 1966,
A BOAC 707,
near the mount Fuji, disintegrated
in a mountain wave rotor
High winds, crushing over mountain peaks
leave so called wind rotors in the lee side
Invisible highly turbulent downdrafts
that come plunging down with devastating power
and are extremely dangerous to aircraft
We found a great deal of evidence
looking at the surface data
and talking to witnesses in the area...
...that wind-rotors were a possibility
Salottollo has several eye witness reports of
bizarre mountain weather on the day of the crash
One of the most intriguing
is from Howard Darnell...
What the heck was that?
...who's truck was struck
by a powerful gust of wind,
just moments before 585 crashed
But as Greg Salottollo combs through his evidence
the theory that
a wind-rotor knocked the plane from the sky
is getting less and less likely
Greg: There is no evidence that we saw that
on the FDR of Flight 585
What the FDR did show,
was a fast and deadly dropping altitude
as the plane fell to earth.
It has been 21 months since the investigation
in to the crash of United Flight 585 began,
almost two years
in which the NTSB has studied the flight-crew,
the weather...
...the rudder,
and thousands of other pieces of evidence
They'd come up empty handed
For only the 4th time in its history,
the NTSB releases a report...
...which doesn't reach a conclusion
The cause of the crash of Flight 585
is undetermined
We had put a lot of time and effort
in to the investigation
and we just weren't sure what had happened
Bill Adair:
It was like he was tracking a serial killer
He was frustrated that they had not solved 585
He did not want that to happen again
But almost 2 years
after the report on 585 is released...
...the killer strikes again
At 07:00 PM on a clear, windless day
US Air Flight 427 is nearing Pittsburgh
Captain Peter Germano
and First Officer Chuck Emmett
are getting ready for their final approach
Folks, we are from the flight deck
we should be on the ground about 10 more minutes
A sunny sky, it is a little hazy
The flight attendants:
Please, preparing for landing
I ask you to check the security seat belts,
Thank you
US Air 309, descending, maintain 6000 ft
As they close in on the airport,
the pilots are on the look out for another flight
about 10 km ahead of them
Looking for the traffic
Turning 100
US Air 427
I see the jet-stream
As they pass through the turbulence,
left behind by the other flight
their jet suddenly and alarmingly rolls left
Nothing the pilots do, seems to have any effect.
What the hell is this?
427, Emergency
Rescue crews arrive quickly
but the fate of flight 427 is tragically clear
There is no hope for the 132 passengers and crew
The human carnage is so bad
authorities declare the crash site a bio hazard
US Air 427 accident was the first
US accident where bio hazard suits were used
and it made it more difficult
they were uncomfortable,
they were hot
and to this day when I put
on a pair of rubber gloves,
for any reason I am instantly transformed
back to the site in Pittsburgh
Captain John Cox, a 737 pilot,
and a flight-system specialist with
the Air Line Pilots Association
is asked to join the team,
investigating the crash of Flight 427
As coroners attempt to collect human remains
NTSB lead investigator Tom Haueter already knows
his hunt for clues will be long and painstaking
When we first arrived at the crash site,
first of all there was no aircraft there
there were only bits and pieces of the airplane
It wasn't really recognizable as an airplane
With the help of eye witnesses,
information from the FDR and the CVR
investigators begin quickly to
see some striking similarities
between 427 and the
unsolved case of United 585
In fact,
they seem to be mirror images of each other
On final approach United 585 rolls right
while US Air 427 rolls to the left
Both crews are caught by surprise
and after just a few terrifying seconds,
both aircrafts plummet straight into the ground
Certainly the whole team was aware
the previous accident was United 585
in Colorado Springs
which right to keep that in the back of our minds:
and take a look at this one
as what it presents to us
As the investigation continues,
the list of similarities grows
427's engines were also attached and functioning
at the time of impact
But for all the similarities,
there is one important difference
Unlike United 585,
as US Air 427 approaches Pittsburgh,
weather conditions were dead-calm
Folks from the flight-deck
we should be on the ground
about 10 more minutes
A sunny sky, it is a little hazy
Taking a look at the FDR information
the aircraft approaching Pittsburgh
is an extremely smooth night
there is just no turbulence at all
The pilots were relaxed,
they were talking about the landing
Flight attendants, please prepare for landing
I ask you to check the security seat-belts,
thank you
As he did in the case of United 585
Greg Phillips will once again
lead the investigation
in to the mechanical
aspects of the crash
Almost immediately, he makes a promising discovery
Miraculously, much of US Air 427's tail and rudder
appear intact
The hydraulic devices inside the tail
have also sustained very little damage
Phillips and Haueter prepare to send the parts
to the manufacturer, Parker Hannifin,
for testing as soon as possible
They need answers
Pressure on the NTSB to solve the accident
is growing quickly.
Not only are the crashes of Flights 585 and 427
disturbingly similar
both of them involve the same kind of airplane:
a Boeing 737
But with serious questions raised
about the plane's safety
billions of dollars and perhaps
the airline industry itself
are at risk
We could not live with the fact as investigators
of having two unsolved 737 accidents
The airplane is now too much used,
too wide around the world
It carries too many people every day
Unsolved was not an acceptable answer
Tom: If 427 was an undetermined accident
we could not find the cause of the accident
there was a great chance that if there
was a third accident with the 737 fleet
under similar circumstances
that the 737 fleet would be grounded
Be careful with that
The investigation into the crash of Flight 427
may be the most important
in the history of the NTSB
But it won't be easy
Answers are still years away
In just 3 years two Boeing 737's have crashed
in the United States with no survivors
In both cases,
the planes were moments from landing
and in both cases,
the planes were under full power
but the pilots were unable to control their jets
In the crash of United 585
NTSB investigators were unable to find the cause
Now, they are searching for
clues into the 2nd crash:
US Air Flight 427
As investigator in charge I
never allowed myself to think:
This investigation,
we go undetermined
We kept on pushing, we kept on researching
as long as there were things to research
we kept on going
To find their killer,
the NTSB cannot afford to rule anything out
From the possibility
that a collision with birds brought 427 down...
to strange, even bizarre theories
They looked at electromagnetic interference
they got calls from people saying:
It might be Russian death rays
They considered everything
There are a couple of witnesses
who gave reports of the aircraft
suddenly descend and hovering before it blew up,
we discarded those
But the investigations primary suspect
is the dual servo valve
Part of the PCU that moves the 737's rudder
and a suspect in the crash of the United 585
Parker Hannifin made the valve
At its lab in California,
investigators look inside the main cavity
of the US Air Power Control Unit
Just like in the earlier crash,
they find tiny chips of metal,
floating in the hydraulic fluid
but once again,
Parker and Boeing repeat their claim
Filters, designed to stop any debris from
interfering with the delicate metal slides
have done their job
Investigator Greg Phillips
wants to be absolutely sure
If the chips were blocking the slides
they would have left tiny scratch-marks behind
where they rub against the metal
but Phillips cannot find any
Another pass
Phillips has technicians put the
servo valve from Flight 427
through as many tests as he can think of
trying to find a weakness
If he can find one, it could explain
why two planes were ripped from the sky
but he comes up empty
That unit passed all the operational tests
there wasn't any indication that it failed
and it operated within the parameters
we expected it
Once again, the investigators are forced
to shift their focus back to the pilots
By studying the plane's FDR
investigators know that the jet's rudder
was deployed fully to one side
what is called rudder hard over
We were definitely focused on rudder
on a hard over rudder
full rudder input for about 20 seconds
It can be caused either by
something unknown in the hardware
or it can be caused by pilot input
first Officer Chuck Emmett who was flying 427
did indeed step down hard on his rudder
and then held it there
while the plane plummeted towards the earth
It raised a grisly question:
Was he trying to fly the plane into the ground?
In looking at this
(I have been a pilot myself)
this doesn't seem like rational behaviour
What the hell is this?
Human performance specialist Malcolm Brenner
listens closely for evidence on the CVR
Malcolm: In this case,
they had microphones right by their mouths
and you can hear as well as in real life or better
you can hear breathing sounds
Yeah, I see the jet-stream
The cockpit recordings indicate
that Flight 427's troubles
began at the moment it flew through
the jet wake of a Delta Airlines Boeing 727
that had just passed in front of them
Both pilots are startled by the wake
First Officer breaks off at the end of a sentence:
"I see the jet stream...'
and there is no more discussion of
the jet stream or anything else,
they both focus: something happened here
The Captain says: Jesus
It was such a smooth flight
that it was a momentary jolt
that they just hadn't anticipated
and with that,
the pilots got out of controls
and immediately put in the rudder input
Jesus!
The CVR even records the thumping sound
of the jet-stream turbulence
as 427 flies through it
As Flight 427 encounters the turbulence,
Brenner hears something unusual
First Officer Emmett begins to grunt
The grunting is unusual
The controls are designed
so that pilot don’t need to grunt
They are especially designed
to around human capabilities
So, to have someone grunting
is typically a sign of an emergency
By matching data from the FDR
with the crew's voices
Brenner is able to confirm that Emmet's grunts
begin a split second after he pushed down
on the rudder pedal
And 3 to 4 seconds
after the wake turbulence affected Flight 427
On their own,
the voice recordings prove very little
but it seems clear
that the crew weren't try to crash their plane
Something happened which took them by surprise
They reacted as quickly as they could
but nothing they did seem to help
It has been almost two years
since the crash of Flight 427 in 1994
and the investigation has stalled
Now, two 737s have gone down
in startlingly similar ways
and investigators still don't know why.
We were all frustrated as months were into years
What were we missing?
Bill Adair:
It definitively took a toll on the personal lives
They worked incredibly long hours
They never stopped thinking about it
We were going up against an aircraft
that had an incredible safety history
It was really...everything...
you could see, for 30 years,
this has been a great airplane
we were trying to prove there was something wrong
with a straight-A student
It clearly was on his mind,
he at one point had a nightmare about it
where he dreamed that he was in front of
a congressional committee that was grilling him on
Now, there had been a third 737 crash
and in Tom's dream all the camera's were
pointing to him and the congressman asked
Why didn't you ground the fleet?
Unsure of where to look next,
and with the trail of evidence getting colder
investigators need a break in the case.
and fast
Eastwing 517, you are cleared for landing
On June, 9th 1996, they finally get the break
they've been looking for
Captain Brian Bishop is on final approach
to Richmond, Virginia
when, without warning,
his Eastwing jet rolls sharply to the right
we didn't know what to what extend
but we knew we had a problem with the rudder
I turned the yoke the opposite direction
I stood on the opposite rudder pedal
The pedal didn't move,
For over 30 seconds
the 737 flies in a precarious right bank
as Bishop fights to keep it from rolling over.
Then suddenly,
the unknown forces holding the jet let go
snapping the wings back to horizontal
In a matter of seconds it released itself
It went back to normal
We started the checklist
almost before I could finish the sentence
All of a sudden, there was a ...
For a 2nd time, the 737 is pushed onto its side
for 30 harrowing seconds
the 737 takes on a life on its own
Then once again,
as quickly as it began, the rollover stops
After the 2nd time
I looked to the first officer and said:
'Declare an emergency
Tell the controller
we have flight control problems'
As they slow down to land, the risks increase
If a third rollover occurs,
they won't have enough airspeed to recover
I did at some point tell my first officer
to look out the window
and find a dark spot
It was night time and we were looking
to avoid a neighbourhood or a populated area
He very calmly responded:
Hey, here is a spot over here
But there is no third rollover
Bishop brings Flight 517 in, high and fast
and lands safely
Taxing in,
I realized my legs were shaking
We get the aircraft to the gate
and I did pick up the P.A.
to make an announcement
to try to explain to these people
what just had happened
I am picking up the microphone,
I realized there was nothing I could say...
...to make this any better
Probably for the first time in a long time
I lost the words
I simply put the microphone down
But Bishop won't remain speechless for long
By the next day,
the investigation team has arrived in Richmond
The Flight Data Recorder was undamaged,
the airplane undamaged, we launched to the scene
The airplane literally didn't move
until we got down there
There were a lot of FAA, a lot of NTSB
and they all wanted to talk to us very badly
Bill: It gave the NTSB a tremendous break
because suddenly,
they had a 737 that had had a rudder incident
that was intact
and they had a pilot who was alive
and who could talk about it
I think they were much happier
to have the airplane than me
I think the airplane probably
gave them more to research than I ever could
NTSB investigators quickly determine
that what happened on board Eastwing Flight 517
is alarmingly similar
to events on Flights 427 and 585
If they can discover why Bishop's 737 rolled over
they may be able
to crack two mysterious and fatal accidents
When we said: 'What happened', they said:
There was something wrong with the rudder pedal
The pedal wouldn't go down
I was standing on the rudder pedal
and I couldn't get it to go down
With Bishop's first person testimony,
investigators immediately zero in
on Eastwing's rudder controls
The PCU is removed,
inspected and then tested again and again
To the frustration of everyone...
...the unit performs perfectly
Tom: We tested that aircraft as is,
it was intact, we went through it completely
We did a flight test with it
and it passed all tests
After a 5 year hunt for clues,
a third mysterious rudder event on a 737
and a live pilot as a witness
Tom Haueter still lacks the evidence he needs
to crack his case
He decides to push his chief suspect,
Flight 427's rudder controls , a little harder
One fellow mentioned a test
he had done in the military
a thermal shock
where if you had the actuator very cold
and put it in very hot hydraulic fluid
it would cause it to react in strange ways
So, we put together a thermal shock test
and this test was extreme, to say the least
On August, the 26th, 1996, in Valencia, California
NTSB investigators gather
to watch the torture test
of US Air 427's PCU
After soaking it in dry ice,
the PCU is blasted with nitrogen gas
to simulate the -40° temperatures at 10,000 m
Then, it is quickly injected
with superheated hydraulic fluid
and given the command to start working
As we were standing there,
listening to the actuator move left and right...
John Fox: It stopped
and it was not commanded to stop
It just jammed, stopped working completely
Take a look
Systems investigator Greg Phillips
now asks that the valve be taken apart
and scanned for scratches
They find none
Look at that, it doesn't leave a trace
It is a crucial breakthrough
to solving an almost perfect crime
Not only have they proven that
the valve which controls the rudders can jam,
no evidence is left behind
Tom Haueter and his team have now found
that a hydraulic valve that controls the rudder
of the world's most popular commercial jetliner
can jam in the right circumstances
It is an ominous discovery
but incredibly, there is another shocking
surprise in store for the investigators
October, the 15th 1996
For the last 5 years,
the NTSB has been struggling
to crack its toughest case
Two completely separate,
but seamingly linked accidents
the crash of United 585
killed 25 passengers and crew
3 years later, the US Air Flight 427 disaster
took another 132 lives
Now, after examining hundreds of clues,
investigators have made a surprising discovery
A new test has revealed that
under the right circumstances,
the hydraulic valve that moves the 737's rudder
can jam.
But the surprises aren't over.
The most important breakthrough came when a
Boeing engineer examining the data from that test
discovered some numbers that indicated
that the valve at that point
had actually reversed
It is a stunning revelation:
Not only can the servo valve jam
but it can then function in reverse
It means that any time a pilot tries
to correct a roll over by pushing on the rudder
the rudder might turn in the opposite direction
causing a fatal accident
And the reversal is like driving your car
you turn to the right
and it goes left
You are not going to figure out this failuremode
until you go off the road
And these cases is where the
pilots were faced with,
something so unusual that they didn't understand
what was happening
We had the evidence now that the valve was unique
That the valve not only could jam
but would reverse
That would explain
why the First Officer, Chuck Emmet
would keep his foot
on the rudder panel
because he is thinking:
Why isn't the plane going right?
and he is feeling
that the plane is going to the left
To the very end, Chuck Emmett pushes hard
hoping his rudder will help him
pull out of his deadly spiral
Tragically, he has no way of knowing that he
is steering the aircraft straight into the ground
They were driven to Colorado Springs
and then gotten sick
Satisfied that they've determined
the cause of the crash of US Air 427
the NTSB turns its attention
to the unsolved case of United 585
Going back to Colorado Springs
and you could follow a progression
of what the captain was doing
He is close to the ground and suddenly
under rudder-reversal he put a little bit of pedal
the pedal violently pushes his leg back
rudder reversal certainly fits
what I know about this crew and how it fits
We were able to show the failure mode,
it matched the FDR from each aircraft
So we now had a lot more information
that we can apply to United 585
and based on that, we re-did the accident report
From rudder reversal to impact
took less than 10 seconds
585's flightcrew had no chance
to save their plane or passengers
in the aftermath of the investigation
sweeping changes were made
to improve the safety of the 737
and the entire aviation industry
New training protocols were designed
to help pilots react to unusual inflight events
In the 737 fleet,
pilots are now trained on how to react
to both rudder hard overs and reversals
The scenario of the
US Air 427 accident
if the crew had the information
that we have today
I believe they would have landed safely
in Pittsburg that evening
The FAA also directed Boeing
to redesign the rudder's dual servo valve
to elimimate the potential for reversal
Boeing spent hundreds
of millions of dollars
to replace the valves on thousands
of 737's around the world
Tom: One thing we don't like as the NTSB
is to have an undetermined accident
because then,
we cannot make a change to improve safety
So, out of US Air Flight 427, United 585,
we have a much safer 737
It took NTSB tin kickers 10 years
to solve the mysterious crashes
of Flights 585 and 427
the longest investigation in aviation history.
Bill Adair: There is still some people in aviation
who don't think the NTSB got it right
But I became convinced that after talking to many
many people, pilots, engineers, people at Boeing
and spending a lot of time with the investigators
that they did get it right
Since the replacement of the 737's servo valves
there hasn't been a similar
crash of the most popular,
most profitable plane in the world.
Narrator
Jonathan Aris
Subtitles
Rein Croonen
passenger jets in the world
Around the globe the plane has carried
more than 12 billion passengers
It is the backbone of the aviation industry
But in 1991, something happened on-board a 737
that send shatters through the world of aviation
Oh, my Lord
A deadly crash as investigators scrambling
There was a time when I dealt
to be able to solve it
It was like he was tracking a serial killer
The hunt for answers will take
10 long and gruelling years
The fate of the airline industry
hangs in the balance
and the mystery isn't solved
until more than a 150 people...
...are dead
This is a true story
It is based on official reports
and eyewitness accounts
Air Crash Investigation Season 04
Hidden danger
09:40 AM
March 3rd 1991
After a short 17 minute trip from Denver,
United Airlines Flight 585 is on
final approach on Colorado Springs
It looks like a perfect day for flying
but there is trouble in the air.
Nice looking day,
Hard to believe the skies are unfriendly
There has been heavy turbulence during the flight
and violent gusts of wind
are forecast over Colorado Springs
They were driven to Colorado Springs
and then gotten sick
At the controls
is 52 year old captain Harold Green
a pilot with 20 years experience
and a sterling reputation
Green's copilot is Patricia Eidson
At 42, she is one of the first female
flight officers in United Airlines' history
Flight attendants, prepare for landing?
At Colorado Springs Municipal Airport
Air Traffic Controller James Rayfield
is ready to bring Flight 585 in
United 585, report the airport in sight
You got it?
Airport in sight, United 585
Lower landing gear
United 585 is cleared for a visual approach
to runway 35
Weather conditions:
Wind 320 degrees at 16 gusts to 29
As its speed decreases,
Flight 585 becomes more
vulnerable to the turbulence
Eidson wants to know
what other planes have experienced on landing
Any reports lately
of any loss or gain of airspeed?
Yes, ma'am
500 ft at 15 knot loss
at 400 ft a 15 knot gain
At 150 ft a gain of 20 knots
It sounds adventurous, thank you
Less than 3 km from the airport
a retired policeman, Howard Darnell
is on his way to a local flea market
A kilometre overhead,
Green and Eidson focus on keeping
their speed constant as they descend
Awful lot of power to hold that airspeed
As United 585 approaches the runway
Darnell feels something strange
What the heck was that?
Out of nowhere,
a powerful gust of wind strikes his
vehicle, almost blowing him off the road
Another 10 knot gain
30 flaps
From the control tower,
James Rayfield can now see
Flight 585's final approach
As the aircraft closes in on the airport
the ride gets even bumpier
Then, without warning,
the 737 starts to spin out of control.
Oh, my Lord
Crash, crash
Rescue workers arrive within minutes
but there is almost no sing of the 737
The shattered remains of the 38 tonnes jet
lie buried in a fire-blackened impact crater
The plane didn't bounce,
like when a plane normally comes and lands
It just went nose down
I came down here...
It was horrible
There are no survivors
All 20 passengers and 5 crew-members
are killed instantly
by the high-speed impact
and exploding jet fuel
In 10 violent seconds
Colorado Springs has become the site of
one of the most mysterious air-crashes
in aviation history
By nightfall, investigators from the NTSB
descend on Colorado Springs
Known to insiders as tin kickers,
NTSB investigators examine
over 2000 aviation accidents/year
at times by picking through the metal debris
of fallen aircraft
While coroners mark the location
of human remains in red
NTSB investigators mark scraps of metal in yellow
looking for clues to help them
solve the mystery of Flight 585
Like investigating a mass murder
it is a tough job walking onto a crash site
Among the investigators assigned to the case
is Malcolm Brenner
a specialist in human performance
His job will be to find out
if the crash was caused by pilot error
The area was cordoned off by police
and there were Salvation Army trucks
I got a cup of coffee, a cup of hot chocolate
or something
and I thank them for
and they said: No, no, thank you
and they had this look in their eyes like:
My God, you have to go into this site
Clues to the fate of the United 585
lie mangled in a deep black hole
The fuselage is crushed like an accordion
in the impact crater
The rest of the plane is in pieces,
spread over an area smaller than a football-field
There was a lot of fire-damage,
there have been a fire afterwards
and it was all contained
in a relatively small area
which, just an initial impression,
it can be a sign that the airplane was intact
If there was a mid-air explosion
or something came off the airplane
you'd expect that to be a much larger site
My first sense that it was going to take some time
in investigating the accident
was the damage that we saw
and the parts, they were burned and broken
the process always takes longer
But with their work just beginning
members of the NTSB have no clue
that the case of United 585
will become the longest crash investigation
in aviation history
A clear late winter-day in 1991
turned deadly in just 10 short seconds
Moments from landing in Colorado Springs,
United Flight 585 fell out of the sky at 370 km/hr
All 20 passengers and 5 crew-members died
The NTSB begins a painstaking investigation
into the crash
Engines turbines, hydraulic pressure gauges...
the CVR and the FDR
are all carefully extracted from the site,
photographed and sent to the lab for analysis
An important first step in the investigation
is the analysis of the CVR
With pilot error, a factor in 70% of air-disasters
Malcolm Brenner's job is to see what role
pilots Green and Eidson played in the crash
This crew was one of the more impressive crews
that I have ever dealt with
There is a little bit of tension release,
a little bit of humour
The captain said:
They were driven to Colorado Springs
and then gotten sick
The first officer suggested that they
added extra speed as a safety margin
The captain agreed with it ,
there was good interaction
Airport in sight United 585
Lower landing gear
This was the sense of an excellent crew...
...caught randomly, if anything
so again my first impression was
This would be consistent more
with a hardware situation
As more about Flight 585 becomes known
mechanical failure becomes a serious suspect
It appears increasingly likely
that the plane had suffered a catastrophic
problem with its flight controls
Investigators quickly become suspicious
of the rudder (at the back of the tail)
We focused in after eliminating
other flight control surfaces
that could contribute to the roll
We start looking at the rudder
Investigators begin their examination
of the rudder on site
but the violence of the crash
makes the job extremely difficult
most of the plane's parts
are too crushed or burned for testing
but a vital component is still reasonably intact:
The Power Control Unit or PCU
Used constantly during flight,
especially during landings
the PCU performs like a cars power steering
When the pilot pushes on the rudder pedal
the PCU uses hydraulic fluid
to convert gentle movements of a pilot's foot
into the pressure,
needed to move the 737's enormous rudder
The heart of the PCU is something
called the dual servo valve
Shaped like a soda can,
it has two slides which glide passed one another,
directing the flow of pressurized hydraulic fluid
that moves the rudder
The servo valve is very unique
that it is in effect two valves in one
and that creates a whole range of interactions
that don't occur
in a more conventional hydraulic valve
When a technician opens the Power Control Unit
chips of metal are found,
floating in the hydraulic fluid
It is a disturbing find
These particles could cause
the servo valve to jam,
making it impossible to work the rudder
It is a chilling prospect:
Could a microscopic fault
bring down a 38 tonnes jet?
It is difficult for Phillips to tell
While more intact than much rest of the wreck,
the PCU and dual servo valve are both damaged
The airplane crashed and burned
in a pretty confined area
and there was a lot of damage
to the flight control components
and the things we were testing
and needed to test and look at
The more damaged the components are
the harder it is to take measurements
and do functional testing
To test what he does have,
Phillips travels to California
to the labs of Parker Hannifin,
where the rudder control unit is made
The curious metal chips,
floating in the PCU's chambers, are dismissed
Phillips is told that filters keep
them out of the delicate servo valve
that directs fluid
and moves the rudder
Nothing else is found
that could explain any sudden
movement of the rudder on Flight 585
We didn't have any absolute indication
or information that we could point to
that said the rudder PCU, servo valve
or any part of that flight control system
caused that accident
With Phillips at a dead end
only bad mountain weather
remains as a primary suspect
An expert on weather related aviation accidents
Greg Salottollo is trying to determine if heavy
winds on the day of the crash were a factor
There is a history of events
where there have been airplane accidents
contributed to mountain waves or rotors
In 1966,
A BOAC 707,
near the mount Fuji, disintegrated
in a mountain wave rotor
High winds, crushing over mountain peaks
leave so called wind rotors in the lee side
Invisible highly turbulent downdrafts
that come plunging down with devastating power
and are extremely dangerous to aircraft
We found a great deal of evidence
looking at the surface data
and talking to witnesses in the area...
...that wind-rotors were a possibility
Salottollo has several eye witness reports of
bizarre mountain weather on the day of the crash
One of the most intriguing
is from Howard Darnell...
What the heck was that?
...who's truck was struck
by a powerful gust of wind,
just moments before 585 crashed
But as Greg Salottollo combs through his evidence
the theory that
a wind-rotor knocked the plane from the sky
is getting less and less likely
Greg: There is no evidence that we saw that
on the FDR of Flight 585
What the FDR did show,
was a fast and deadly dropping altitude
as the plane fell to earth.
It has been 21 months since the investigation
in to the crash of United Flight 585 began,
almost two years
in which the NTSB has studied the flight-crew,
the weather...
...the rudder,
and thousands of other pieces of evidence
They'd come up empty handed
For only the 4th time in its history,
the NTSB releases a report...
...which doesn't reach a conclusion
The cause of the crash of Flight 585
is undetermined
We had put a lot of time and effort
in to the investigation
and we just weren't sure what had happened
Bill Adair:
It was like he was tracking a serial killer
He was frustrated that they had not solved 585
He did not want that to happen again
But almost 2 years
after the report on 585 is released...
...the killer strikes again
At 07:00 PM on a clear, windless day
US Air Flight 427 is nearing Pittsburgh
Captain Peter Germano
and First Officer Chuck Emmett
are getting ready for their final approach
Folks, we are from the flight deck
we should be on the ground about 10 more minutes
A sunny sky, it is a little hazy
The flight attendants:
Please, preparing for landing
I ask you to check the security seat belts,
Thank you
US Air 309, descending, maintain 6000 ft
As they close in on the airport,
the pilots are on the look out for another flight
about 10 km ahead of them
Looking for the traffic
Turning 100
US Air 427
I see the jet-stream
As they pass through the turbulence,
left behind by the other flight
their jet suddenly and alarmingly rolls left
Nothing the pilots do, seems to have any effect.
What the hell is this?
427, Emergency
Rescue crews arrive quickly
but the fate of flight 427 is tragically clear
There is no hope for the 132 passengers and crew
The human carnage is so bad
authorities declare the crash site a bio hazard
US Air 427 accident was the first
US accident where bio hazard suits were used
and it made it more difficult
they were uncomfortable,
they were hot
and to this day when I put
on a pair of rubber gloves,
for any reason I am instantly transformed
back to the site in Pittsburgh
Captain John Cox, a 737 pilot,
and a flight-system specialist with
the Air Line Pilots Association
is asked to join the team,
investigating the crash of Flight 427
As coroners attempt to collect human remains
NTSB lead investigator Tom Haueter already knows
his hunt for clues will be long and painstaking
When we first arrived at the crash site,
first of all there was no aircraft there
there were only bits and pieces of the airplane
It wasn't really recognizable as an airplane
With the help of eye witnesses,
information from the FDR and the CVR
investigators begin quickly to
see some striking similarities
between 427 and the
unsolved case of United 585
In fact,
they seem to be mirror images of each other
On final approach United 585 rolls right
while US Air 427 rolls to the left
Both crews are caught by surprise
and after just a few terrifying seconds,
both aircrafts plummet straight into the ground
Certainly the whole team was aware
the previous accident was United 585
in Colorado Springs
which right to keep that in the back of our minds:
and take a look at this one
as what it presents to us
As the investigation continues,
the list of similarities grows
427's engines were also attached and functioning
at the time of impact
But for all the similarities,
there is one important difference
Unlike United 585,
as US Air 427 approaches Pittsburgh,
weather conditions were dead-calm
Folks from the flight-deck
we should be on the ground
about 10 more minutes
A sunny sky, it is a little hazy
Taking a look at the FDR information
the aircraft approaching Pittsburgh
is an extremely smooth night
there is just no turbulence at all
The pilots were relaxed,
they were talking about the landing
Flight attendants, please prepare for landing
I ask you to check the security seat-belts,
thank you
As he did in the case of United 585
Greg Phillips will once again
lead the investigation
in to the mechanical
aspects of the crash
Almost immediately, he makes a promising discovery
Miraculously, much of US Air 427's tail and rudder
appear intact
The hydraulic devices inside the tail
have also sustained very little damage
Phillips and Haueter prepare to send the parts
to the manufacturer, Parker Hannifin,
for testing as soon as possible
They need answers
Pressure on the NTSB to solve the accident
is growing quickly.
Not only are the crashes of Flights 585 and 427
disturbingly similar
both of them involve the same kind of airplane:
a Boeing 737
But with serious questions raised
about the plane's safety
billions of dollars and perhaps
the airline industry itself
are at risk
We could not live with the fact as investigators
of having two unsolved 737 accidents
The airplane is now too much used,
too wide around the world
It carries too many people every day
Unsolved was not an acceptable answer
Tom: If 427 was an undetermined accident
we could not find the cause of the accident
there was a great chance that if there
was a third accident with the 737 fleet
under similar circumstances
that the 737 fleet would be grounded
Be careful with that
The investigation into the crash of Flight 427
may be the most important
in the history of the NTSB
But it won't be easy
Answers are still years away
In just 3 years two Boeing 737's have crashed
in the United States with no survivors
In both cases,
the planes were moments from landing
and in both cases,
the planes were under full power
but the pilots were unable to control their jets
In the crash of United 585
NTSB investigators were unable to find the cause
Now, they are searching for
clues into the 2nd crash:
US Air Flight 427
As investigator in charge I
never allowed myself to think:
This investigation,
we go undetermined
We kept on pushing, we kept on researching
as long as there were things to research
we kept on going
To find their killer,
the NTSB cannot afford to rule anything out
From the possibility
that a collision with birds brought 427 down...
to strange, even bizarre theories
They looked at electromagnetic interference
they got calls from people saying:
It might be Russian death rays
They considered everything
There are a couple of witnesses
who gave reports of the aircraft
suddenly descend and hovering before it blew up,
we discarded those
But the investigations primary suspect
is the dual servo valve
Part of the PCU that moves the 737's rudder
and a suspect in the crash of the United 585
Parker Hannifin made the valve
At its lab in California,
investigators look inside the main cavity
of the US Air Power Control Unit
Just like in the earlier crash,
they find tiny chips of metal,
floating in the hydraulic fluid
but once again,
Parker and Boeing repeat their claim
Filters, designed to stop any debris from
interfering with the delicate metal slides
have done their job
Investigator Greg Phillips
wants to be absolutely sure
If the chips were blocking the slides
they would have left tiny scratch-marks behind
where they rub against the metal
but Phillips cannot find any
Another pass
Phillips has technicians put the
servo valve from Flight 427
through as many tests as he can think of
trying to find a weakness
If he can find one, it could explain
why two planes were ripped from the sky
but he comes up empty
That unit passed all the operational tests
there wasn't any indication that it failed
and it operated within the parameters
we expected it
Once again, the investigators are forced
to shift their focus back to the pilots
By studying the plane's FDR
investigators know that the jet's rudder
was deployed fully to one side
what is called rudder hard over
We were definitely focused on rudder
on a hard over rudder
full rudder input for about 20 seconds
It can be caused either by
something unknown in the hardware
or it can be caused by pilot input
first Officer Chuck Emmett who was flying 427
did indeed step down hard on his rudder
and then held it there
while the plane plummeted towards the earth
It raised a grisly question:
Was he trying to fly the plane into the ground?
In looking at this
(I have been a pilot myself)
this doesn't seem like rational behaviour
What the hell is this?
Human performance specialist Malcolm Brenner
listens closely for evidence on the CVR
Malcolm: In this case,
they had microphones right by their mouths
and you can hear as well as in real life or better
you can hear breathing sounds
Yeah, I see the jet-stream
The cockpit recordings indicate
that Flight 427's troubles
began at the moment it flew through
the jet wake of a Delta Airlines Boeing 727
that had just passed in front of them
Both pilots are startled by the wake
First Officer breaks off at the end of a sentence:
"I see the jet stream...'
and there is no more discussion of
the jet stream or anything else,
they both focus: something happened here
The Captain says: Jesus
It was such a smooth flight
that it was a momentary jolt
that they just hadn't anticipated
and with that,
the pilots got out of controls
and immediately put in the rudder input
Jesus!
The CVR even records the thumping sound
of the jet-stream turbulence
as 427 flies through it
As Flight 427 encounters the turbulence,
Brenner hears something unusual
First Officer Emmett begins to grunt
The grunting is unusual
The controls are designed
so that pilot don’t need to grunt
They are especially designed
to around human capabilities
So, to have someone grunting
is typically a sign of an emergency
By matching data from the FDR
with the crew's voices
Brenner is able to confirm that Emmet's grunts
begin a split second after he pushed down
on the rudder pedal
And 3 to 4 seconds
after the wake turbulence affected Flight 427
On their own,
the voice recordings prove very little
but it seems clear
that the crew weren't try to crash their plane
Something happened which took them by surprise
They reacted as quickly as they could
but nothing they did seem to help
It has been almost two years
since the crash of Flight 427 in 1994
and the investigation has stalled
Now, two 737s have gone down
in startlingly similar ways
and investigators still don't know why.
We were all frustrated as months were into years
What were we missing?
Bill Adair:
It definitively took a toll on the personal lives
They worked incredibly long hours
They never stopped thinking about it
We were going up against an aircraft
that had an incredible safety history
It was really...everything...
you could see, for 30 years,
this has been a great airplane
we were trying to prove there was something wrong
with a straight-A student
It clearly was on his mind,
he at one point had a nightmare about it
where he dreamed that he was in front of
a congressional committee that was grilling him on
Now, there had been a third 737 crash
and in Tom's dream all the camera's were
pointing to him and the congressman asked
Why didn't you ground the fleet?
Unsure of where to look next,
and with the trail of evidence getting colder
investigators need a break in the case.
and fast
Eastwing 517, you are cleared for landing
On June, 9th 1996, they finally get the break
they've been looking for
Captain Brian Bishop is on final approach
to Richmond, Virginia
when, without warning,
his Eastwing jet rolls sharply to the right
we didn't know what to what extend
but we knew we had a problem with the rudder
I turned the yoke the opposite direction
I stood on the opposite rudder pedal
The pedal didn't move,
For over 30 seconds
the 737 flies in a precarious right bank
as Bishop fights to keep it from rolling over.
Then suddenly,
the unknown forces holding the jet let go
snapping the wings back to horizontal
In a matter of seconds it released itself
It went back to normal
We started the checklist
almost before I could finish the sentence
All of a sudden, there was a ...
For a 2nd time, the 737 is pushed onto its side
for 30 harrowing seconds
the 737 takes on a life on its own
Then once again,
as quickly as it began, the rollover stops
After the 2nd time
I looked to the first officer and said:
'Declare an emergency
Tell the controller
we have flight control problems'
As they slow down to land, the risks increase
If a third rollover occurs,
they won't have enough airspeed to recover
I did at some point tell my first officer
to look out the window
and find a dark spot
It was night time and we were looking
to avoid a neighbourhood or a populated area
He very calmly responded:
Hey, here is a spot over here
But there is no third rollover
Bishop brings Flight 517 in, high and fast
and lands safely
Taxing in,
I realized my legs were shaking
We get the aircraft to the gate
and I did pick up the P.A.
to make an announcement
to try to explain to these people
what just had happened
I am picking up the microphone,
I realized there was nothing I could say...
...to make this any better
Probably for the first time in a long time
I lost the words
I simply put the microphone down
But Bishop won't remain speechless for long
By the next day,
the investigation team has arrived in Richmond
The Flight Data Recorder was undamaged,
the airplane undamaged, we launched to the scene
The airplane literally didn't move
until we got down there
There were a lot of FAA, a lot of NTSB
and they all wanted to talk to us very badly
Bill: It gave the NTSB a tremendous break
because suddenly,
they had a 737 that had had a rudder incident
that was intact
and they had a pilot who was alive
and who could talk about it
I think they were much happier
to have the airplane than me
I think the airplane probably
gave them more to research than I ever could
NTSB investigators quickly determine
that what happened on board Eastwing Flight 517
is alarmingly similar
to events on Flights 427 and 585
If they can discover why Bishop's 737 rolled over
they may be able
to crack two mysterious and fatal accidents
When we said: 'What happened', they said:
There was something wrong with the rudder pedal
The pedal wouldn't go down
I was standing on the rudder pedal
and I couldn't get it to go down
With Bishop's first person testimony,
investigators immediately zero in
on Eastwing's rudder controls
The PCU is removed,
inspected and then tested again and again
To the frustration of everyone...
...the unit performs perfectly
Tom: We tested that aircraft as is,
it was intact, we went through it completely
We did a flight test with it
and it passed all tests
After a 5 year hunt for clues,
a third mysterious rudder event on a 737
and a live pilot as a witness
Tom Haueter still lacks the evidence he needs
to crack his case
He decides to push his chief suspect,
Flight 427's rudder controls , a little harder
One fellow mentioned a test
he had done in the military
a thermal shock
where if you had the actuator very cold
and put it in very hot hydraulic fluid
it would cause it to react in strange ways
So, we put together a thermal shock test
and this test was extreme, to say the least
On August, the 26th, 1996, in Valencia, California
NTSB investigators gather
to watch the torture test
of US Air 427's PCU
After soaking it in dry ice,
the PCU is blasted with nitrogen gas
to simulate the -40° temperatures at 10,000 m
Then, it is quickly injected
with superheated hydraulic fluid
and given the command to start working
As we were standing there,
listening to the actuator move left and right...
John Fox: It stopped
and it was not commanded to stop
It just jammed, stopped working completely
Take a look
Systems investigator Greg Phillips
now asks that the valve be taken apart
and scanned for scratches
They find none
Look at that, it doesn't leave a trace
It is a crucial breakthrough
to solving an almost perfect crime
Not only have they proven that
the valve which controls the rudders can jam,
no evidence is left behind
Tom Haueter and his team have now found
that a hydraulic valve that controls the rudder
of the world's most popular commercial jetliner
can jam in the right circumstances
It is an ominous discovery
but incredibly, there is another shocking
surprise in store for the investigators
October, the 15th 1996
For the last 5 years,
the NTSB has been struggling
to crack its toughest case
Two completely separate,
but seamingly linked accidents
the crash of United 585
killed 25 passengers and crew
3 years later, the US Air Flight 427 disaster
took another 132 lives
Now, after examining hundreds of clues,
investigators have made a surprising discovery
A new test has revealed that
under the right circumstances,
the hydraulic valve that moves the 737's rudder
can jam.
But the surprises aren't over.
The most important breakthrough came when a
Boeing engineer examining the data from that test
discovered some numbers that indicated
that the valve at that point
had actually reversed
It is a stunning revelation:
Not only can the servo valve jam
but it can then function in reverse
It means that any time a pilot tries
to correct a roll over by pushing on the rudder
the rudder might turn in the opposite direction
causing a fatal accident
And the reversal is like driving your car
you turn to the right
and it goes left
You are not going to figure out this failuremode
until you go off the road
And these cases is where the
pilots were faced with,
something so unusual that they didn't understand
what was happening
We had the evidence now that the valve was unique
That the valve not only could jam
but would reverse
That would explain
why the First Officer, Chuck Emmet
would keep his foot
on the rudder panel
because he is thinking:
Why isn't the plane going right?
and he is feeling
that the plane is going to the left
To the very end, Chuck Emmett pushes hard
hoping his rudder will help him
pull out of his deadly spiral
Tragically, he has no way of knowing that he
is steering the aircraft straight into the ground
They were driven to Colorado Springs
and then gotten sick
Satisfied that they've determined
the cause of the crash of US Air 427
the NTSB turns its attention
to the unsolved case of United 585
Going back to Colorado Springs
and you could follow a progression
of what the captain was doing
He is close to the ground and suddenly
under rudder-reversal he put a little bit of pedal
the pedal violently pushes his leg back
rudder reversal certainly fits
what I know about this crew and how it fits
We were able to show the failure mode,
it matched the FDR from each aircraft
So we now had a lot more information
that we can apply to United 585
and based on that, we re-did the accident report
From rudder reversal to impact
took less than 10 seconds
585's flightcrew had no chance
to save their plane or passengers
in the aftermath of the investigation
sweeping changes were made
to improve the safety of the 737
and the entire aviation industry
New training protocols were designed
to help pilots react to unusual inflight events
In the 737 fleet,
pilots are now trained on how to react
to both rudder hard overs and reversals
The scenario of the
US Air 427 accident
if the crew had the information
that we have today
I believe they would have landed safely
in Pittsburg that evening
The FAA also directed Boeing
to redesign the rudder's dual servo valve
to elimimate the potential for reversal
Boeing spent hundreds
of millions of dollars
to replace the valves on thousands
of 737's around the world
Tom: One thing we don't like as the NTSB
is to have an undetermined accident
because then,
we cannot make a change to improve safety
So, out of US Air Flight 427, United 585,
we have a much safer 737
It took NTSB tin kickers 10 years
to solve the mysterious crashes
of Flights 585 and 427
the longest investigation in aviation history.
Bill Adair: There is still some people in aviation
who don't think the NTSB got it right
But I became convinced that after talking to many
many people, pilots, engineers, people at Boeing
and spending a lot of time with the investigators
that they did get it right
Since the replacement of the 737's servo valves
there hasn't been a similar
crash of the most popular,
most profitable plane in the world.
Narrator
Jonathan Aris
Subtitles
Rein Croonen