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  • 6/6/2025

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00:01Go around. Hold the glove.
00:10Near Zurich airport, a DC-9 plows into the ground six miles short of the runway.
00:16It was a fatal loss of life. It was a tragedy.
00:20You have impressions and smells that you never forget. It changes you.
00:25Pitch and roll, fine. Flaps, good. No stabilization problems.
00:32Close analysis of the evidence only deepens the mystery.
00:36It was definitely flying too low, but why, we didn't know.
00:39I think it was something we can't see.
00:41Could a hidden fault deep inside the airplane have led the two pilots down a deadly path?
00:47That put all the other aircraft in the sky in danger.
00:50Mayday, mayday.
00:57Oh, fuck.
00:593-1-0, we're having yards, thank you.
01:01I'm not going to wait to see you.
01:03That's zero.
01:04MOBIAS
01:24Zurich good evening, Alitalia, 404...descending 100...
01:31Echo received
01:38The crew of Alitalia flight 404 is nearing the end of an evening flight to Zürich, Switzerland
01:47Fly heading 325 radar vectors to ILS 14
01:52Radar vectors to runway 14 on heading 325
02:01Captain Raffaele Liberty is a senior Alitalia pilot with more than 20 years experience
02:09How much is the visibility visibility is nine kilometers
02:13First officer Massimo de Freya is the pilot flying the plane tonight
02:18He's new to the airline having joined just last year
02:25Franco Bergante also flew for Alitalia in the 1990s
02:31At the time it was one of the safest companies and best trained in the world
02:42I knew the captain very well the co-pilot a little less
02:49There are four flight attendants and 40 passengers in the cabin
02:55Thank you
02:57Several of the passengers are Swiss industrial workers heading home after a lengthy stretch of work
03:04I'll be nice to get back home for all this time away
03:07Let's hope they recognize us
03:10Typical passengers were employees
03:14Going back and forth from Switzerland to Italy especially to Milan
03:20The plane is a McDonnell Douglas DC-9 that's been flying since 1974
03:26The DC-9 was one of the mainstays of the industry and from the 1960s through the 2000s
03:32It was very very popular in the US Western Europe and around the world
03:37Primarily for shorter regional trips
03:40Even if it wasn't among the more modern planes it was a good airplane
03:44Flight 404 left Milan's Linate airport 25 minutes ago
03:54The flight path takes it almost directly north over the Alps to Zurich's Cloten airport
03:59At Zurich air traffic control it's a busy evening
04:12Swiss 3611 maintain 230
04:15The airport is one of Europe's main hubs serving 12 million passengers a year
04:19Alitalia 404 turn right heading 340
04:23Right 340 Alitalia 404
04:27Alitalia 404 is lining up for its approach to the airport
04:34You should slow down a bit the faster you go the less time you have for landing
04:37Alitalia 404 reduced to 210 knots
04:42210 knots reducing 404 you see
04:49The pilots are preparing for what's called an ILS or instrument landing system approach
04:55The instrument landing system is a series of technologies primarily radio transmitters on the ground
05:03That allows an aircraft to align itself both vertically and horizontally with the runway
05:08Alitalia 404 reduced to 180 knots
05:13Reducing 180404
05:16The crew sets the navigation instruments to pick up the ILS signal from the runway
05:34Radio unconfirmed
05:35There's a set of signals which goes out at an angle from the ground
05:40That gives them an idea of the glide slope which is typically around a three degree slope
05:46Gives you one tiny pencil thin beam that you can fly down that ensures that you're you're going to
05:53Stay above the trees and not hit anything below there and it'll lead you right to the end of the runway
06:00I'll tell you 404 reduced to 160 knots
06:17Reducing 160
06:22Captured Loke captured glide paths so we're on the beam
06:25Flight 404 is third in line on approach the runway 12 miles straight ahead
06:33The pilots can't see it yet, but their navigation instruments show they are locked on to the proper signals
06:39All they need to do now to finalize the approach is intercept a radio beacon known as the outer marker
06:57The outer marker is something like the last
07:00Occasion to check whether the ILS is correct
07:04That tells them as they get closer that they're still right on the money
07:09Flaps 25
07:13Flaps 25
07:15The outer marker check is at 1250 feet almost four miles
07:21Didn't we pass it?
07:24Didn't we pass the outer marker?
07:26No, no, it hasn't changed yet
07:29Alitalia 404 speed as convenient contact tower 118.1
07:34118.1 goodbye
07:39That doesn't make sense to me
07:40The runway should be just ahead
07:43But the first officer still can't see it
07:45Something's not right
07:52Go around
07:52No, no, no, no
07:53Hold the glide
07:56Can you hold it?
07:57Yes, sir
07:57That's right there
07:58Lufthansa 1034 reduced to 160 knots, Alitalia 404.
08:25The controller has no idea why Alitalia 404 has suddenly disappeared from radar.
08:33Rabbit 932, established ILS-14.
08:36Rabbit 932, do you see an aircraft ahead of you?
08:39Stand by.
08:41No traffic in sight, but there's fire on the ground.
08:44Roger.
08:45It can only mean one thing.
08:47This is air traffic control. We have an emergency.
08:55Swiss and German firefighters rush to the site of the crash of Alitalia flight 404,
09:02a forested hillside six miles from Zurich's Kloten airport.
09:10At first, you could see a glow in the woods, and there was a taste of burning rubber.
09:15And when we could finally see the actual crash site, it was horrific.
09:24The plane has cut a sway through the trees, scorching the surrounding area.
09:33The scale of the destruction is staggering.
09:36The airplane was completely destroyed.
09:42The main goal was to save people.
09:46But as fire crews suppress the flames and comb through charred debris,
09:51they can find no one to save.
09:54All 46 people aboard the flight are dead.
09:57I was very upset, because it was a loss of someone close.
10:09You have images that you have to deal with.
10:13You have impressions and smells that you never forget.
10:16It changes you.
10:18With the wreckage still smoldering,
10:21an investigation into what happened is already underway.
10:27Hans-Peter Graf is with Switzerland's Air Accident Investigation Bureau, or AAIB.
10:34First of all, it's, well, bad news.
10:37It's going to be a big and long investigation.
10:40I had to get the first impression of what had actually happened that night.
10:45So I went straight to Air Traffic Control Center in Zurich.
10:51Hello.
10:52Good evening.
10:53Good evening.
10:54Graf meets with the last person to speak,
10:57to the Alitalia crew.
11:01What can you tell me about Flight 404?
11:04I hope to learn if the crew had issued an emergency beforehand,
11:08if there was anything unusual about the airplane.
11:11It was routine.
11:13They were making an ILS approach, as usual.
11:18Oh.
11:19They never reported any problems.
11:22Can you replay the radar track?
11:26Yes, of course.
11:31Graf knows that most control centers keep recordings of all recent radar tracks.
11:37I had a closer look at the radar screen itself.
11:41I saw the airplane symbol, AZ-404, together with the altitude reading on the screen.
11:48Well, they may not have reported a problem, but they sure had one.
11:52Look at that glide slope.
11:55Graf discovers that more than five minutes before the crash,
11:58Flight 404 was already too low and descending lower.
12:03I noticed that the airplane was flying 1,200 feet below the actual flight path.
12:12The proper glide slope would have taken the DC-9 on a gradual descent,
12:16right to the foot of the runway.
12:19Instead, the plane flew an almost parallel path,
12:22more than 1,000 feet lower, right into the side of a small mountain.
12:26You didn't notice their altitude?
12:29Well, I was juggling six flights.
12:32All the 404 calls were normal.
12:35They said they were on glide.
12:37That particular controller was assumed,
12:39if they were reporting they were lined up with the runway
12:42and that they were on the glide path,
12:44that they were safely above any terrain.
12:47And your minimum safe altitude warning system didn't sound?
12:51We don't have one installed as of yet.
12:53Unfortunately, at the time, you know,
12:57they didn't have the minimum safe altitude warning system in place in Zurich.
13:01In the U.S., it had already been in place for 10 years.
13:05You said they were doing an ILS approach.
13:07Mm-hmm.
13:09Then we don't have a choice.
13:11Shut the system down immediately.
13:13We can't risk another flight.
13:15Graf worries the runway guidance system may be malfunctioning.
13:19A full test of the system will cause major disruptions for Zurich Airport,
13:24but it has to be done.
13:26If the ground transmitter was malfunctioning,
13:30that put all the other aircraft in the sky in danger.
13:33So they have to shut it down until they have it checked out by electronic technicians.
13:37It could take a day or more to get results.
13:41But if the testing reveals a fault with the ILS,
13:45it could explain why Alitalia Flight 404 ended in tragedy.
13:55Daylight reveals a 300-meter-long scar
13:58through a hillside forest northwest of Zurich,
14:02where Alitalia 404 crashed hours earlier.
14:05Joining the investigation is Bob Benzen
14:11of the U.S. National Transportation Safety Board.
14:14Because the aircraft was manufactured in the United States,
14:17our role is really to assist the Swiss government
14:19in determining what happened.
14:24That's a lot of fire damage.
14:26It's going to make ID and parts a real chore.
14:30The thing that stuck out was the amount of destruction.
14:32The only truly recognizable things were the engines and the landing gear.
14:40But the rest of it was pretty well burnt up.
14:44Did you see that map again?
14:46Investigators wonder what the mangled terrain
14:49can tell them about the plane's last moments.
14:51It looked to us like the aircraft had struck the trees
14:56in a bit of a level attitude,
14:59although parts of the right wing
15:01had been sheared off by the trees.
15:04And that caused a more lift to occur
15:06on the left side of the aircraft,
15:09causing the aircraft to roll.
15:10So the eventual impact was nearly inverted.
15:12Benzen gets word on Zurich Airport's instrument landing system.
15:23That's for certain.
15:26Okay.
15:28Overnight testing has revealed
15:30that the guidance technology is in perfect working order.
15:34Captured LOC.
15:36Captured glide paths so we're on the beam.
15:38It means the ILS was sending the proper signal
15:42throughout Flight 404's descent to the airport.
15:48The ILS is fine.
15:51So whatever brought that plane down,
15:53the evidence has got to be here.
15:56Somewhere.
15:57That led us to believe that perhaps
15:59there was a problem on board the aircraft
16:01rather than on the ground.
16:03More answers about the mysterious crash
16:07may be close at hand.
16:09The team has recovered both of the plane's black boxes.
16:15But they won't know if the data they need
16:18has survived the crash
16:19until they get the recorders to a lab for analysis.
16:25So they were cleared for runway 14.
16:28It looks like they're on the right heading.
16:31They're way too low.
16:34It's like they don't even know the hill's there.
16:37Wonder how well the pilots knew the route.
16:41Searching for answers,
16:42investigators look into the pilots' work records.
16:46They discover that besides being a senior Alitalia pilot,
16:51the captain was also a former military airman.
16:54We learned that the captain had over 10,000 flying hours.
16:59Zurich, good evening.
17:00Alitalia, 4-0-4, descending 1-0-0.
17:04Echo received.
17:06What's more, the Milan to Zurich route was nothing new to him.
17:10The captain who was flying this route many times in his career
17:13was pretty familiar with it.
17:15They learned that the 28-year-old first officer was far less experienced.
17:20But his record is spotless, and he'd also landed at Zurich before.
17:24Both pilots had flown this route many times before in the same cockpit sometimes.
17:29So they were familiar with what the approach should look like.
17:35Across Zurich and throughout Europe, news of the crash has left people rattled.
17:40The quiet city, best known for its banking sector,
17:44hasn't seen a major air disaster in almost 20 years.
17:53There was such a tragedy.
17:56It was an all-fatal loss of life.
17:59And so it was reported in the media extensively.
18:02The media attention puts mounting pressure on investigators.
18:08Is this the flight data?
18:10Finally, they have some good news.
18:12Information from both the flight data recorder
18:14and the cockpit voice recorder has survived.
18:19We should get this up on the projector.
18:20But will it provide the answers investigators need?
18:25Was there an aircraft malfunction of some sort,
18:29an instrument failure, a flight crew problem?
18:32Those are the immediate things that you zero in on.
18:39Well, there's not a lot of parameters,
18:41but it should tell us something.
18:44Investigators begin with the flight data,
18:47looking for any sign of a mechanical problem on board.
18:51Thrust is good.
18:53Although the thing was reasonably ancient
18:56compared to the modern ones,
18:58it only had 10 parameters.
18:59Two of those parameters were engine pressure ratio,
19:02which means how much thrust the engines were putting out.
19:05And they showed us that the engines were operating normally
19:09up until the time of impact.
19:11Pitch and roll, fine.
19:14Flaps, good.
19:15Yep.
19:16No stabilization problems.
19:18Everything seems normal from a mechanical standpoint.
19:22Even the glide is smooth and straight.
19:24It's just all over 1,000 feet too low.
19:26I don't get it.
19:28The data doesn't reveal any mechanical failure
19:31that can explain the crash.
19:33It only confirms the mysterious glide path
19:36recorded by air traffic control radar.
19:38On the FDR data,
19:40we could not find any technical issues at all.
19:43The airplane performed as per design.
19:51It was definitely flying too low.
19:54But why, we didn't know.
19:56We set up the playback machine.
19:58We need to hear what was going on in that cockpit.
20:00Trying to understand why a well-trained Alitalia crew
20:13flew their DC-9 into the ground,
20:16miles short of the runway,
20:18investigators now turned to the cockpit recording.
20:21Something was going wrong with the perceptions of the crew,
20:25perhaps the aircraft itself,
20:26to cause it to be almost 1,000 feet,
20:29maybe a little bit more,
20:30below where it should have been on the approach.
20:33So that became a focus.
20:42But as soon as they start listening to the recording,
20:45they know they have a problem.
20:47There was a lot of noise.
20:49And it was, first of all,
20:53difficult to understand.
20:56Sounds like they weren't using their headsets
20:59for some reason.
21:01You should slow down.
21:03The flight crew weren't using boom microphones.
21:07They were just talking into one single microphone
21:11located in the middle of the instrument panel.
21:13So this led to some of the words
21:19not being understood by the accident investigators.
21:23Send it back to the lab.
21:24We won't be able to get anything off it.
21:26It's a disappointing setback.
21:29Investigators can only hope lab technicians
21:31can find a way to filter out the noise
21:34and produce an audible recording.
21:36So it was very difficult for the investigators
21:39to create a true transcript.
21:41In a facility at Zurich airport,
21:48investigators survey wreckage
21:49recovered from Alitalia flight 404.
21:53They're looking for any clue
21:55that might help explain
21:56why the DC-9 flew for more than five minutes
22:00on a fatally low glide path
22:02before plowing into a hillside.
22:07I'm surprised there are planes
22:08that still have this altimeter.
22:10They're ancient.
22:11What if they misread their altitude?
22:15The DC-9's cockpit was equipped
22:18with what's known as a drum pointer altimeter.
22:21The drum pointer altimeter
22:23is known to be prone to be misread.
22:26You have to look at the drum
22:27and then you have to look at the needle.
22:31And it's almost like an analog watch
22:33versus a digital watch.
22:35Unlike a modern digital altimeter,
22:37the drum pointer design can only be read in two steps.
22:43Feet in thousands is indicated on a drum
22:46like an odometer in a car.
22:48Feet in hundreds is indicated by a pointer
22:51that moves around a scale like a clock face.
22:53The problem with the design is as it moves,
22:59the pointer can sometimes obstruct the pilot's view
23:02of the numbers on the drum.
23:04If that needle happened to be obscuring part
23:07of the odometer that showed the thousands of feet,
23:09there could be some confusion
23:10as to whether it was one particular altitude
23:13or maybe a thousand feet away from that.
23:14So the potential for confusion existed.
23:17The industry has been phasing out
23:19the notoriously confusing instrument for years,
23:22but it's still found on older planes
23:25like DC-9's from the mid-70s.
23:30At this stage in the investigation,
23:32the team has no way of knowing
23:34if the pilots misread the instrument.
23:37They did misread it.
23:39That could explain why they were so low on approach.
23:43But the GPWS would have warned them.
23:50The Ground Proximity Warning System, or GPWS,
23:54is an onboard technology designed
23:56to help pilots avoid terrain.
23:59The system bounces radio waves off the ground below
24:03to measure altitude and sounds a cockpit warning
24:06if the plane gets too low.
24:09And there's no mistake in that alarm.
24:13Investigators know the Alitalia DC-9
24:16was equipped with a GPWS.
24:19But did the pilots get a warning
24:21before the fatal impact?
24:24We really need that CVR.
24:26They hope to finally get some answers
24:42from the cockpit recording,
24:44now cleaned up by audio technicians
24:46and ready for playback.
24:47The picture that was given by the full transcript
24:51is more than enough to get a very good idea
24:53of what the sequence of events was
24:56in the cockpit.
24:58Okay.
25:01Can we do a radio approach?
25:03Yes.
25:06We're at just over 4,000 feet here,
25:10which is well below the glide slope.
25:12Okay, so, but they need to level off
25:15to capture the glide,
25:17but they kept ascending.
25:21On one.
25:22Let's do it on one.
25:24Radio one confirmed.
25:26Sounds like they're just on radio one.
25:28ILS transmitters send radio signals
25:33to two navigational receivers in the cockpit,
25:36NAVRADIO-1 and NAVRADIO-2.
25:40The pilots can use either one to guide the plane.
25:45Investigators now know
25:46the crew selected NAVRADIO-1,
25:48but they're still hoping to discover something
25:51about the unusual low glide slope
25:53and about the GPWS.
25:55I'll tell you, 404 reduced to 160 knots.
26:00Reducing 160.
26:03Capture glide paths.
26:04So we're on the beam.
26:06Stop it there?
26:08On the beam?
26:10They're well below the glide slope there.
26:12They are more than 1,000 feet below it.
26:16So why is the captain saying then
26:17that he captured that?
26:19What they're hearing from the cockpit
26:21only deepens the mystery.
26:23Investigators know
26:26that right in front of both pilots
26:28is an instrument that should be showing
26:29their exact glide slope position.
26:33It's called a glide slope indicator.
26:38There are visual cues,
26:40specific systems that are in place
26:42that give a pilot an idea
26:44whether or not they're too high
26:45or too low on the glide slope.
26:47Did they misread the altimeter
26:50and the glide slope?
26:52I mean, that doesn't seem possible.
26:56Let's keep listening for the GPWS.
26:59Okay.
27:01Flaps 25.
27:02Flaps 25.
27:05The outer marker check is at 1,250 feet,
27:07almost four miles.
27:10Didn't we pass it?
27:13Didn't we pass the outer marker?
27:15No.
27:16No, it hasn't changed yet.
27:17Something in that cockpit
27:20is confusing these pilots.
27:22I'll tell you 404.
27:23Speed as convenient.
27:24Contact tower 118.1.
27:28118.1.
27:29Goodbye.
27:30That doesn't make sense to me.
27:32Go around.
27:32No, no, no.
27:34Hold the glide.
27:36The CVR had the first officer
27:38attempting to go around
27:39and then being countermatted
27:41by the captain.
27:42There was a lot of confusion there.
27:44Can you hold it?
27:45Yes, sir.
27:46No, no, no, no, no!
27:54Investigators are stunned
27:55both by what they've heard
27:57and by what they haven't heard.
28:00No ground proximity warnings at all.
28:02The fact that the aircrew
28:03didn't get a warning
28:04from the ground proximity warning system
28:07was a surprise to us.
28:11And the captain called off a go around.
28:12They now face more questions than ever.
28:17How could two professional pilots both misread their glide slope indicators?
28:22Why did the plane's ground proximity warning not sound?
28:26Go around.
28:27And why did the captain call off the one maneuver that might have saved his plane and his passengers?
28:37This one looks pretty peed up too.
28:39Investigators examine a pair of flight instruments recovered from the cockpit of Alitalia 404,
28:47the heading indicators, known as HSIs.
28:51They hope the damaged instruments can confirm whether or not the pilots misread their glide slope on approach to Zurich.
28:59They recovered the HSI from the racket.
29:03We wanted to know what was the indication of the glide slope.
29:08OK, so that mark there, is that the same as on the first one?
29:12They closely examine a small arrow on the glide slope indicator, situated on the right side of each HSI.
29:20It's the instrument that tells the pilots if they're flying too high or too low.
29:24We found what we call slap marks, which means the indicator, as it was being destroyed, the needles on the indicator slapped against the background.
29:36So, at the time of impact, you could determine what that instrument was showing you.
29:42It did have markings on it showing that they were on glide slope.
29:46So, they were both indicating on glide.
29:48It's a major discovery.
29:51It means that both indicators were on the glide slope, and the pilots didn't misread them.
29:57Captured look.
29:59Captured glide paths.
30:01So, we're on the beam.
30:02The captain announced capture because his instrument was showing him he was on the proper descent path,
30:08even though he was actually more than a thousand feet below it.
30:11They got what's called a false glide slope.
30:17And that kind of led us to wonder how that could occur.
30:24The team now needs to understand why critical cockpit instruments were displaying the wrong glide slope.
30:32With help from Alitalia, they begin examining the onboard source of that information, the number one navigation receiver.
30:41Did the unit have some kind of defect that caused it to send a faulty signal?
30:47I couldn't understand why can the autopilot fly a faulty glide path?
30:54Why the pilots don't get warned about that?
30:56There must be something totally wrong with this receiver.
30:59I don't see any corrosion.
31:02All the internal components seem to be in the right place.
31:06No obvious defects.
31:08Maybe it's something that we can't see, like a short circuit.
31:11Well, we had a very good idea that the NAV-1 receiver was putting out false information,
31:17but we couldn't directly test it because of damage to the device during the accident sequence.
31:23So, the Swiss investigators decided to do some testing.
31:27Investigators start by deliberately shorting out a NAV-1 receiver
31:31and then testing it in a flight simulator to see what happens.
31:35Okay. It should be in the menu.
31:37I pre-programmed the route as 404 approach.
31:41Simulation tests are important during an accident investigation
31:45because what you're trying to do is recreate the scenario and circumstances
31:50that led up to the accident.
31:53Then they simulate the flight path of Alitalia 404.
31:58We're 15 miles out, 1,200 feet below glide.
32:04Stand by.
32:06Graf wants to see if he can reproduce the same false glide path that deceived the Alitalia crew.
32:13Switch to Radio 1.
32:17There it is.
32:18A false glide indication on the display.
32:23And no warning flags.
32:27Graf is stunned to see that the short-circuited receiver defaults to the on-glide position
32:33and that there's no warning about the malfunction.
32:36Typically, if the signals are not correct,
32:40there's some sort of warning given in the instrument itself.
32:43There was no warning.
32:45I was really surprised that somebody could design a piece of equipment
32:50without warning the pilots if there's something wrong with it.
32:55It was a kind of an aha moment.
32:59Captured Loke.
33:00Captured glide paths.
33:02So we're on the beam.
33:03There was now no doubt that a short-circuit in the NAV-1 receiver
33:08caused the deadly glide-slope display malfunctioning.
33:12Did it also somehow disable the potentially life-saving ground proximity warning?
33:19Keep going.
33:21That's what Graf wants to know next.
33:2530 seconds from impact.
33:27The simulation soon gives him an answer.
33:31Nothing.
33:33It should have sounded by now.
33:35The plane's GPWS never sounds a warning.
33:40And it turns out that if the navigation radios aren't putting out a good signal
33:44to the rest of the aircraft, the GPWS, it just doesn't work.
33:52The GPWS finding leads to another disturbing question.
33:57That doesn't make sense to me.
33:58Would the crew have been able to save their plane and 40 passengers?
34:03Go around.
34:04No, no, no, no.
34:05Hold the glide.
34:07If the captain had initiated a go-around when his first officer called for it.
34:12Okay, so no hesitation when I give the order, okay?
34:21We're almost there.
34:24Five, four, three, two, one.
34:28Go around.
34:33Climbing safely.
34:34Those poor bastards.
34:36Had the captain not intervened, they would have made it.
34:40The aircraft would have passed over the top of the mountain without striking it.
34:52Not by much.
34:53You know, a couple hundred feet perhaps.
34:54It's a heart-breaking discovery.
34:58One that motivates investigators to try to understand why the fatal decision was made.
35:04Why did a seasoned pilot overrule his first officer and miss his last chance to avoid disaster?
35:14Let's take it from earlier in the flight.
35:16Sure.
35:16For more insight into what the captain may have been thinking, they return to the cockpit voice recording.
35:27How is it approaching?
35:29Approaching.
35:30Turning left to Schatzhausen.
35:33They listen from earlier in the approach to try to get a sense of how well the pilots were working together.
35:39I told you not to go on that beacon.
35:41It was a crew that had a very experienced fellow in the left seat and a very inexperienced fellow in the right seat.
35:49And that always causes a bit of a consternation at times during a flight.
35:55Go to the left.
35:55You see?
35:56You had moved.
35:57What emerges is troubling.
35:59The captain seems constantly dissatisfied with his first officer.
36:03It's compulsory to go there.
36:05There seemed to be some sort of mentor-student relationship.
36:08The first officer being admonished at some points by the captain.
36:11You should slow down a bit.
36:13The faster you go, the less time you have for landing.
36:17I'll tell you, 404, reduced to 210 knots.
36:21210 knots reducing.
36:24404.
36:26You see?
36:26My impression is that the captain didn't trust the co-pilot's abilities, because he already showed that he wasn't very sure what he was doing.
36:41Not exactly an ideal working relationship.
36:44The captain was a bit tough, and the co-pilot was a bit weak.
36:54So let's say that the absence of crew coordination definitely influenced the flight.
37:02This doesn't make sense to me.
37:03It seems that when the critical moment came, and the captain had only a split second to decide.
37:12Go around.
37:13No, no, no, no, no, no, no.
37:14Hold the glide.
37:15His opinion of the younger pilot may have colored his decision.
37:19When the first officer attempted the go-around, the captain, at an instant, didn't trust him to make a good decision.
37:26If there had been a bit more trust between them, who knows?
37:32Investigators now understand the human factors that were at play.
37:36But the technical failure at the heart of the accident needs further examination.
37:42Other planes could be at risk.
37:48Investigators need to learn more about the DC-9's design.
37:52Thanks for coming right away.
37:54They want to know why the Alitalia crew were not warned when one of their nav radios failed.
38:00We needed to work together with the manufacturer of the airplane, McDonnell Douglas.
38:06So this is the system they use for Nav1.
38:08It's an older model, what's known as an unmonitored receiver.
38:13Investigators learn that the receiver in question is a King KNR-6030.
38:18Unlike newer models, the King receiver doesn't monitor the signal it sends to the HSI.
38:26This means it can't warn pilots if the signal becomes interrupted.
38:32What's more, in the event of a short circuit, the glide slope indicator will display a centered or on-glide position.
38:39This receiver should have been banned from any airplanes.
38:44It should never have been possible to install them.
38:48That is my opinion.
38:49So the pilots had no way to know that it had malfunctioned.
38:56Well, there would be other clues in the cockpit.
39:01Unfortunately, there are devices within the cockpit that could have given them an indication of something going wrong.
39:07They had a standby altimeter that wasn't affected by this navigation problem at all.
39:12Well, why didn't you warn the airlines?
39:14We did.
39:15We even had a seminar to inform pilots.
39:18There were at least a couple of the Alitalia guys there.
39:22Investigators are surprised to learn that six years earlier, McDonnell Douglas sent a letter describing the problem to all DC-9 operators.
39:31Whenever you possibly can, you remove the hazard.
39:35That's the first rule.
39:36If you can't do that, the second rule is you warn the person about the hazard.
39:41That's what they did in this case.
39:44So it looks like the airline really dropped the ball.
39:48One can't rely on pilots overhearing something in a conference and then overhearing it in the break room and they implement changes.
39:56That's not how it's done.
39:57This is a very organized, very procedures-based world where learning has to go through a process.
40:08For some reason, that information never drifted down to the line crew member level.
40:13We were pretty convinced that the accident crew members had no idea this false reading could exist.
40:20Investigators now understand the sequence of events that doomed Alitalia 404.
40:32It starts with an aging DC-9 carrying 40 passengers, four flight attendants, two pilots, and a hidden danger.
40:44Do you have the glide slope?
40:45A flaw in the navigation system.
40:52On one.
40:53Let's do it on one.
40:55Radio on confirmed.
40:57With this receiver, the best pilot in the world would be at risk.
41:01It would fool anybody.
41:04On approach to Zurich, flight 404 descends below its intended glide path.
41:10Alitalia 404, descend to 4000, turn right, heading 110.
41:19The busy air traffic controller fails to notice.
41:23The pilots also don't notice, perhaps because of a notoriously confusing altimeter.
41:30Captured glide path, so we're on the beam.
41:31But certainly, due to a false glide slope indication.
41:37Radio 1 had a non-glide slope indication, telling him, okay, we are fine, we are on the correct flight pass to the runway.
41:45A disabled GPWS keeps them unaware of the danger until...
41:52Go around.
41:53No, no, no, no, no, no.
41:54Hold the glide.
41:55The captain's lack of trust in his young first officer seals their fate.
42:11Depend the blame on any one of them.
42:13The pilot's role, the air traffic controller's role, the manufacturer of the technology, their role is unfair.
42:21This was a multiple input event.
42:25In its final report, the Swiss Air Accident Investigation Board calls for the prompt removal from service of all unmonitored radio receivers.
42:36If there's any doubt about the functioning of a piece of equipment that has to ensure the safe landing of an airplane,
42:46it has no place in the airplane any longer.
42:48They also recommend that airlines give first officers more authority in critical flight situations.
42:56After the accident, the procedure was changed, so that if the co-pilot sees something wrong and calls for a go-around,
43:08and the captain doesn't execute it, he's authorized to do it by himself.
43:17The accident brought important improvements to Zurich Airport as well.
43:26It was after that, that Zurich installed the minimum safe altitude warning system in its ATC facility,
43:33and so unfortunately it took that tragedy to happen, but, you know, at least some positive things resulted from it.
43:40We learn from every accident, even though they're tragic events, frankly, some good comes out of every single one of them.
43:48And the recommendations that came out of this accident have led to an aviation system today that is very, very safe.