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Air Crash Investigation Series S20E06 West Air Sweden 294 (Impossible Pitch)
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00:00A jetliner plummets to Earth in the Swedish Arctic.
00:04Mayday! Mayday! Mayday! Air Sweden 294!
00:08Bank angle!
00:09No! No!
00:11Bank angle!
00:15A deep crater reveals an aircraft in an astonishing descent.
00:20It's just far out of bounds with the way we normally fly the airplane.
00:24Investigators are shocked by what they find.
00:27That can't be what the plane was doing.
00:29I flew the jet for 10 years.
00:31They never saw anything even remotely like this.
00:33As the evidence paints a terrifying picture of chaos.
00:36Please!
00:37I don't know. I don't see anything.
00:39And confusion.
00:40If you get past a certain point, that confusion can become terminal.
00:44Why did he let the captain fly the plane into the ground?
00:50Mayday! Mayday!
00:51Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! Mayday! May
01:21one of Sweden's largest cargo companies West Air Sweden we are approaching
01:27Bodo where the outside air temperature is a bombing minus 61 Celsius the 42
01:35year old Spanish captain has more than 3,300 hours of flight time minus 30
01:41well good his French first officer is 33 with a similar number of flight hours
01:49Sweden 294 clear direct to Valen expect a certain approach to runway 01 at Tromsø
01:56Roger something approach for when we won yes we didn't know the experienced flight
02:04crew took off from Oslo Norway just after 11 o'clock for a one-and-a-half-hour hop
02:10to Tromsø high in the Norwegian Arctic
02:14the cargo jet is carrying about four-and-a-half tons of mail to the remote northern community
02:21the CRJ 200 crosses into Swedish airspace as it heads further and further north
02:29Sean Pruchnicki is a pilot who flew the CRJ 200 I'd like the airplane because it has all the bells and
02:39whistles it's just as sophisticated as any of the larger jets the aircraft itself is very fast it's a
02:44very sleek airplane so it's it's a lot of fun to fly ready for the approach breaker let's do it
02:59ILS approach to runway 01 inbound heading 009 it's been a routine flight and the plane is expected to land
03:08in Tromsø in about 30 minutes and turn right acknowledged and according to us
03:15ATIS we can expect light wind and zero what the hell suddenly the captain sees his plane is in a steep climb
03:26he pushes the nose down
03:33what
03:34what
03:35what
03:37oh
03:38oh
03:40oh
03:41oh
03:42oh
03:43oh
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03:58oh
04:00oh
04:02oh
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04:06oh
04:08the pilots can no longer make sense of what the plane is doing
04:12oh
04:14oh
04:15oh
04:16oh
04:17oh
04:18oh
04:19oh
04:20what is the nature of your emergency please
04:22the plane loses almost 10,000 feet of altitude and speeds towards the ground at more than 450 miles an hour
04:31oh
04:32oh
04:33oh
04:34oh
04:35oh
04:36oh
04:37oh
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05:06oh
05:06West Air Sweden flight 294 hits the ground at almost 600 miles an hour.
05:21The plane is obliterated.
05:26It takes three hours before rescue helicopters arrive.
05:31Even from the air, it's obvious the pilots could not have survived.
05:37The information we got from the rescue efforts was that the aircraft was found and also that the accident was most probably not at all survivable.
06:01The crash site is in one of the most desolate places on Earth.
06:06The accident location was in a flat valley in a mountainous area.
06:16The site was at the time very cold with temperatures down towards minus 25 degrees Celsius.
06:26The next day, a team of investigators from the Swedish Accident Investigation Authority, known as the SHK, arrives at the crash site.
06:44The team includes technical investigator Tony Arvidsson.
06:49This far north, they have a very short window to find clues as to what caused the sudden crash of flight 294.
06:57We only had daylight time for about three hours.
07:07Investigators waste no time, analyzing the wreckage to pinpoint the northbound plane's orientation as it crashed.
07:14That's the front of the plane.
07:16That's the front of the plane.
07:19So, they were traveling east.
07:23Finding the four corners of the aircraft confirms the theory.
07:26The tail, the nose, the wingtips, the aircraft had impacted the ground in an easterly direction.
07:38This is the left wing, all right.
07:40But it's in the wrong place for a plane flying east.
07:44This is Arvidsson's first clue about the accident.
07:49The left wing is found in the south end of the crater, and the right wing is in the north end.
07:55For a plane traveling east, it should be the other way around.
07:58If they were coming in this way, and the left wing is over there.
08:09And they must have been upside down.
08:13The crash has also created a crater 20 feet deep.
08:24That tells investigators the plane hit the ground at tremendous speed.
08:28They definitely came in hard and fast.
08:32That's not normal.
08:34You probably don't have a lot of control over the aircraft at that time.
08:39The position of the wreckage and the size of the crater paints a picture of a plane hitting the ground off course,
08:46upside down, and at a blazingly high speed.
08:54Incredibly, both of the plane's black boxes survived the crash.
08:58They're sent to France, where the data can be downloaded.
09:03Investigators hope the data will shed light on why the plane was so badly out of control.
09:08As they continue to scour the site, blackened mail from the cargo hold presents a grim possibility.
09:23We'd be looking at a fire.
09:25An explosion.
09:26A fire or explosion on board could explain why the plane became so badly out of control while cruising at 33,000 feet.
09:38The team gathers as much of the cargo debris for analysis as they can.
09:43They need to determine whether fire was a cause of the accident.
09:59So we send one tonne of cargo to a fire expert.
10:08Elevator goes, along with all the control cables.
10:14This goes too.
10:15The team recovers a total of three and a half tons of wreckage.
10:22Mostly parts from the flight controls.
10:27We try to get as much as possible from the site.
10:31Before fierce winter weather sets in, investigators must abandon the site.
10:56They can only hope the cause of this crash lies somewhere in the pieces they're taking with them.
11:07Swedish investigators hope the Norwegian air traffic controller on duty the night of the crash of flight 294
11:14can help explain why the pilots lost control of their plane at 33,000 feet.
11:19Okay, so the first sign of trouble was a mayday call at 12.19.
11:26Mayday, mayday, mayday, F Sweden 294, mayday, mayday, mayday.
11:30294, understood mayday.
11:32What is the nature of your emergency, please?
11:35So, no explanation for the mayday call?
11:38No, they never said.
11:40It's just a mayday call like this one with not much specificity.
11:44Then there's not much the controller can do other than try to discern what's happening and attempt to help.
11:49He was descending quickly and he started to veer east here.
11:54The radar data confirms what investigators observed at the crash site.
11:59Flight 294 was descending rapidly and veering east just seconds before it disappeared from the screen.
12:07And the return never split?
12:09No, just one blip all the way down.
12:11The radar shows only one return, meaning it didn't break into pieces in midair.
12:16If you have an airplane that came apart at altitude, you're going to see a lot of different radar returns.
12:22If you have one singular return and it doesn't advance forward very much, maybe one more hit and then it's gone, that indicates a dive intact.
12:31The investigators now know the pilots were struggling with a serious onboard emergency.
12:36Thanks for coming down.
12:37But still don't understand what could have caused such a catastrophic loss of control.
12:46In Stockholm, the team inspects the three and a half tons of wreckage for signs of a fatal mechanical failure.
12:52We're looking for a failure of any control surface.
12:59Ailerons, elevators, rudder.
13:03We need to check them all.
13:05An airplane has three primary flight control surfaces.
13:11Ailerons, the control roll.
13:14Elevators that control pitch.
13:15And a rudder that controls yore.
13:19A broken flight control, like the elevators, could cause some problems.
13:25But this is the worst damage Arvidsson has ever seen.
13:29It's impossible for him to get any useful information about flight control surfaces.
13:37This tells me nothing.
13:38We want to make sure that the control surface is working properly, but it was too damaged.
13:47Investigators try to identify the pieces of wreckage based on serial numbers and other markings,
13:52to make sure all the control surfaces were on the plane when it hit the ground.
13:57Left and right ailerons, both elevators, rudder.
14:10We have them all.
14:12We could find and identify all the control surfaces,
14:17which make it most probable that the aircraft was intact all the way down to impact.
14:25They rule out a serious mechanical failure and move on to another theory.
14:32That an onboard fire brought down the plane.
14:37Tests on flight 294's cargo don't offer investigators much more insight than the control surfaces.
14:45No sign of fire or explosion.
14:48The cargo was destroyed at impact.
14:52Not in an onboard fire.
14:54Searching for answers, the investigator in charge, Nicolas Seeger, turns to the flight data,
15:00now in from France and ready for analysis.
15:04The FDR data for us is really important to understand the course of events.
15:11It also helps us to calculate the trajectory of the aircraft.
15:15So they're cruising at 33,000 feet when suddenly they start to pitch way up.
15:23A plane normally changes pitch by about one degree per second.
15:28But in this case you had six degrees per second, so it was a really rapid change of pitch.
15:35Then the plane starts pitching down and starts rolling out of control.
15:41When a plane pitches up, investigators would expect it to climb in altitude and its speed to slow.
16:02But that's not what the data from flight 294 shows.
16:08His airspeed indicator was not changing.
16:11Same with the altitude.
16:13The altitude should have showed a climb if this was good data, and it did not.
16:17That can't be what the plane was doing.
16:21Investigators must get to the bottom of the contradictory data
16:24before they can figure out what brought down West Air Sweden flight 294.
16:30We're going to have to go back and figure out exactly what was going on here.
16:37Investigators in Stockholm try to understand discrepancies in flight 294's flight data.
16:43Okay, so let's assume airspeed and altitude are correct, yes?
16:51The plane's pitch data doesn't make sense.
16:55We made calculations to determine the real pitch of the aircraft during the event.
17:04The calculations point to an astounding conclusion.
17:08So, no pitch up at all.
17:11Not that we can tell.
17:14The calculations indicated that the pitch was actually going down after the start of the event.
17:24Right here, the data shows a steep pitch up, but the plane flies level and then pitches down.
17:38Not up.
17:41What the hell?
17:46It seems the captain thought the plane was pitching up when it was actually flying straight and level.
17:52The discovery leads investigators to a disturbing question.
18:04Were the pilots responding to an emergency...
18:07Come up!
18:08...that didn't actually exist?
18:10If they aren't actually pitching up, why are they pushing the nose down?
18:15The indication that the ADI, the attitude deviation indicator on the captain's side, has suddenly shown a 30-degree pitch up is about the only thing that even comes close to making sense for why this crew would take a perfectly good airplane and do a dive.
18:32Investigators soon discover that it's not just the pitch data that's off.
18:35Right here, heading and roll are wonky, too.
18:40Oh, you see that?
18:41Yeah.
18:42That tells us something.
18:45Yeah.
18:45It's another valuable clue.
18:48When we looked at FDR data, we could see four parameters that were not consistent with the other parameters, and those were the pitch, the roll, the heading and the ground speed.
19:01All four parameters come from what's called an inertial reference unit, or IRU.
19:08It's made up of gyroscopes that provide information to the cockpit displays and to the flight data recorder.
19:16There are two IRUs, one for each pilot's display.
19:20The FDR gets its data from the captain's side, IRU.
19:26Investigators study the plane's manuals and electrical drawings.
19:29We found that the IRU-1 was sending the attitude signal to flight data recorder and the primary flight display number one.
19:42It's an important discovery.
19:44The captain's display and the flight data recorder both get their pitch data from the same source.
19:52Now this is what the captain was seeing.
19:57Investigators are coming to a troubling conclusion.
20:00The captain's instrument was telling him the plane was pitching up when it was still flying level.
20:07And that it was rolling to the right when it was actually rolling left.
20:12The automation is telling him, point the nose down, and he's trying to follow this.
20:17Unfortunately, it's erroneous information, and that eventually leads to a loss of control of the aircraft.
20:23I flew the jet for 10 years.
20:24I never saw anything even remotely like this.
20:26What the hell?
20:31It's now clear the pilot was receiving bad information from a faulty IRU.
20:36The FO's instrument has its own gyro.
20:45Investigators learned that IRU-1 was only feeding the captain's instrument.
20:50A second IRU feeds the first officer's display and is not recorded by the flight data recorder.
20:57So is it possible that both sides could have failed?
21:01If the first officer's instrument was correct, he should have seen that the plane was flying straight and level.
21:08So why did he allow the captain to push the plane into a high-speed dive?
21:15To find out, the team recreates the flight in a simulation based on the data from IRU-1.
21:21Okay, start the animation.
21:24It paints an almost incomprehensible picture.
21:27Three seconds after his instrument shows a pitch up, he pushes the nose down.
21:35The pilots tried to solve the problem by pushing the elevators to nose down.
21:42When the captain pushes the nose down, his ADI continues to show a pitch up.
21:48So he keeps pushing the plane into a steeper and steeper dive.
21:54Then they begin to roll to the left.
21:57The plane continues to roll until it's on its back.
22:01Eventually they do reach a speed of 508 knots.
22:08It is pretty much incredible that the aircraft did not start breaking up because of the aerodynamic forces.
22:13But any control movement at all is going to rip the tail off or going to rip the control surfaces off.
22:18Flight 294 hits the ground inverted at a speed of almost 600 miles an hour.
22:26The speed with which this airplane went from stable flight to a smoking hole, a crater literally,
22:32is just astounding because it involves a descent rate at one point of over 20,000 feet per minute.
22:38That's a straight vertical dive at almost speed of sound.
22:41It means that whatever happened, happened extremely rapidly.
22:46Investigators can now see what happened, but they still don't understand why the failure of a single instrument
22:51led to such a sudden and catastrophic crash.
22:55How do you go from level flight at 33,000 feet to 1,000 kilometers per hour impact in, what, 1 minute 20 seconds?
23:10The failure of one single instrument in a triple redundant system should allow the crew or the operations
23:26to actually cope with this situation.
23:31To better understand how the pilots were interpreting flight data,
23:36investigators now turn to the cockpit voice recording of flight 294.
23:41Let's hear what was happening up there.
23:43Ready for the approach, please?
23:45Let's do it.
23:46Investigators hear no signs of trouble in the minutes leading to the accident, until...
23:53Okay, now this is where the trouble starts.
23:57What the hell?
24:03What?
24:06What?
24:07What?
24:11What?
24:16They're barely talking to each other.
24:20We were a little bit surprised that there were no communication for the first 10 to 12 seconds
24:29after the problem has started.
24:35For some reason, the two pilots never discussed the unusual pitch.
24:39Come on, help me.
24:41Help me.
24:42Help me.
24:43Yes, I'm trying.
24:44I'm trying.
24:44Don't lift.
24:45Don't lift.
24:46Or how to troubleshoot the issue.
24:49Bank angle.
24:50Wait a minute, stop.
24:52Bank angle.
24:52Bank angle.
24:53Bank angle.
24:55When did this start?
24:5813 seconds after the trouble started.
25:0340 degrees.
25:05Exactly when it should come up.
25:06The warning is programmed to sound when the plane's bank angle gets to 40 degrees,
25:12which is precisely when it sounded on flight 294.
25:17In a CRJ-200, the bank angle display and warning get data from the IRU designated to the first officer's side.
25:28Hearing the bank angle call-outs gives the investigation some vital information.
25:32In our fellow reference, unit number two was working as it should be.
25:37The first officer was getting good information.
25:41The discovery confirms the first officer should have known the plane was never pitching up in the first place.
25:48So why did he let the captain fly the plane into the ground?
25:52We need to climb and turn right.
25:57Acknowledged.
25:58Investigators have a new mystery to solve.
26:01And according to last eight tests, we can expect light wind and zero...
26:06What the hell?
26:10When the captain of flight 294 plunges into a deadly dive...
26:15Why didn't the first officer intervene?
26:24As investigators look at the FDR data, they make an important discovery.
26:30The pilots both received what's called a miscompare warning.
26:35The warning is shown on both displays when there's a mismatched reading between them.
26:39In this case, P.I.T. for pitch.
26:43Investigators now know that while the captain saw a sudden 30-degree pitch-up...
26:48And the co-pilots saw a perfectly level aircraft...
26:52Both saw the pitch discrepancy warning.
26:54It's a puzzling find because pilots are trained how to react to the warning.
27:04Come on!
27:05You would hope that communication-wise, you'd be able to verbalize...
27:13I have what appears to be an extreme pitch-up.
27:16What are you showing on your side?
27:19I'm showing a pitch-up.
27:24In the event of a discrepancy, pilots should check a third standby instrument...
27:30To determine which side is wrong and switch the faulty instrument to the working IRU.
27:38Looks like my side's bad.
27:40Switching to IR2 now.
27:46Ideally, what we refer to as a standby attitude indicator...
27:50Could have kind of broken the tie.
27:51In other words, we have three sources of information...
27:54And the best two out of three is what you're trained to go with.
27:57All right.
28:00Let's see what they say next.
28:02But when investigators listen to the CVR...
28:05We need to climb.
28:06Come on, we need to climb.
28:08Yes, yes, we need to climb.
28:08Go left.
28:09Go left.
28:09They don't hear that kind of conversation.
28:14Continue.
28:15Right.
28:15Instead, they hear the sound of a crew that can't figure out what's happening to their plane...
28:21...or how to correct the problem.
28:23Come on, help me.
28:24Help me, please.
28:25I don't know.
28:26I don't see anything.
28:27And what that tells us is that the crew members are both very mentally consumed...
28:34...with looking at their primary flight display...
28:36...trying to figure out actually what is going on.
28:38What is the real position of the aircraft in space?
28:42It's a troubling revelation.
28:44What the hell?
28:45What the most?
28:45What is the real position of the aircraft in the aircraft in medium-time?
28:46What is the real position of the aircraft in the aircraft?
28:48The aircraft in the aircraft?
28:49The aircraft in the aircraft are not going on yet.
28:49Right.
28:50what the pilots experienced when the instruments began to fail they booked
28:55time in a CRJ simulator okay so let's start the air on the left side please
29:03they fly the same route as flight 294 and program a fault into the left side
29:09IRU in the simulator we could observe the two primary flying displays and we
29:19could also see that everything was working according to design there it is
29:27freeze it there please when the captain's ADI shows a sudden climb the
29:33miscompare warning comes on telling the captain and first officer they're seeing
29:38different pitch readings okay all right let's pick it up here then they make a
29:47new discovery now we've got the declutter mode kicking in freeze it there please
30:00all right when a pilot's ADI reaches extreme pitch or roll values it goes into
30:07what's called declutter mode all non-essential information disappears and
30:11red arrows tell the pilots which direction to fly the declutter mode is to
30:19help the pilot focusing on the most important things but that's not the only
30:26insight the flight simulator provides the investigation and guess what
30:31disappears in declutter mode investigators learn that in declutter mode the PIT
30:37discrepancy warning alerting the pilots of mismatched displays also disappears four
30:45seconds after that warning appeared it disappears for good it's not enough time
30:51for the captain to register the problem what the hell and as a result he
30:56instinctively pushes the nose down not realizing he's putting the plane into a
31:01dive soon the first officer's gage also enters declutter mode but in almost the
31:14opposite configuration of the captain's display
31:16now neither one of them has a discrepancy warning this is potentially problematic because the
31:31crew is still trying to figure out what's going on in addition to following the
31:35erroneous automation commands so this box was telling them what the problem was
31:39actually disappears when the situation becomes even more dire
31:44as the pilots were struggling to regain control of their plane yes I'm trying
31:49both were missing a vital piece of the puzzle that their displays were showing
31:57different pitch angles that's one bit of information that really should not have
32:02been removed when it goes to a decluttering function that was the only cue that they
32:07really had that there was potentially a problem between both primary flight displays
32:13investigators now have a picture of what happened in the cockpit
32:17but to figure out why the pilots couldn't tell if they were climbing or diving
32:29investigators will need to take to the skies
32:37investigators fly an identical plane on the same route under the same moonless conditions to find out
32:49what the pilots of flight 294 could and couldn't see on the night of the accident
32:54even when flying at night time there can still be visual cues that can help you understand the orientation of your aircraft
33:15things like you can still see a visible horizon sometimes when there are a lot of city lights
33:20the test seems to be in vain revealing nothing out of the ordinary
33:25okay let's start the descent into tromso
33:29now I can't see anything out there
33:38it was very very difficult to discern the horizon during this flight when you had the cockpit illumination on
33:49investigators have made a major discovery with the cockpit lights turned on it would have
34:03been impossible for the pilots to see the lights below or the horizon the pilots of 294 would likely
34:11have depended entirely on their instruments for guidance instruments that show contradictory information
34:17we need to climb
34:19come on we need to climb
34:20come on we need to climb
34:21yes yes we need to climb don't let don't let
34:22continue right continue right
34:25continue right when we can't see outside we trust our instruments but if your instrument is
34:30telling you something that is completely separate from what your body is telling you
34:34it's not a matter of ignoring one or the other it's a matter of
34:37verifying what the situation is the discovery reveals a critical piece of the puzzle
34:44ready for the approach breather let's do it after the captain of flight 294 switches on the cockpit
34:51lights according to us eight tests we can expect his display begins to indicate a substantial pitch upwards
34:59what the hell but glare inside the cockpit means the pilots can't see the horizon below
35:05the captain can't tell if his plane is actually climbing or not had this happened earlier when
35:11they might have had some form of a visible horizon it could have had an entirely different outcome and
35:17probably would have he sees this so his first reaction is to push his nose down
35:26seager thinks the captain's response
35:28back there yes i'm trying made it impossible for either pilot to make sense of the plane's movements
35:37one of the adages that we have kind of instilled in commercial aviation and in military aviation is
35:42in an emergency order a cup of coffee first before you decide to do something there are very few
35:47things in aviation that need an instantaneous physical response
35:51in less than 30 seconds the plane is upside down and diving
35:57extreme negative g-forces make the pilots feel weightless so they can't tell if they're climbing
36:02or descending
36:05when faced with the negative g environment it's disorienting for many reasons
36:10one of which is that it actually affects your cognitive ability so your ability to understand the
36:15situation that you're in
36:20in just five seconds his autopilot disconnects he's faced with a 30 degree pitch up
36:27and his instrument display changes
36:29that's what's known as the startle or surprise effect in both pilots
36:43that surprised effect uh together with the lack of communication between the pilots can explain the
36:51difficulties there were to solve the problem
36:57this is basically the environment that they found themselves in going from extremely normal
37:02operations to extremely abnormal operations basically within a split second
37:08in a lot of ways this accident is kind of a perfect storm scenario the fact that both crew members
37:23were looking away from their instruments as they were required to do briefing the approach the fact
37:28that the autopilot disconnected so quickly the fact that the indication of pitch was so extreme
37:35the fact that the plane was so extreme
37:40investigators now believe they have pieced together what went so horribly wrong on flight 294
37:50but they still have one final question to answer
37:57ready for the approach breather let's do it
38:00the final minutes of flight 294 are now clear to investigators
38:05ils approach to runway 01 inbound heading 009
38:11the approach briefing is interrupted when the captain notices a sudden climb light wind and zero
38:19what the hell the start of the event was a runaway
38:23on the left side pilot flying display showing an increasing pitch but he has no idea what he's
38:32seeing is from a faulty inertial reference unit the pitch warning disappears the autopilot disconnects
38:40and the captain pushes the nose down following instructions on his adi
38:45as the plane begins to dive the pilots don't know their displays no longer match
38:50what and as they can't see the natural horizon outside
39:00neither pilot can verify their actual attitude as the plunging jet rapidly gains speed
39:07negative g-forces make the pilots feel weightless
39:11flight 294 rolls to the left until it banks upside down
39:15it's possible that this occurred because now the first officer had grabbed the yoke
39:22to steady himself or to possibly try to contribute to solving the problem
39:26upside down and hurtling to earth the first officer's display shows the plane in a nose dive
39:32and banking left
39:37but the captain sees the opposite a plane climbing and rolling right
39:41his first officer's suggestions make no sense and the inverted g-forces make it almost impossible to
39:49think come on help me help me help me help me yes i'm trying thank you don't lift don't lift
39:59when you get sucked into a reality in the middle of the night like this that is not commissar with
40:05what's actually happening in other words it's an induced reality then it begins to get confusing and if
40:10you get past a certain point that confusion can become terminal the plane is in a steep dive nearly
40:18inverted and traveling at speeds approaching 600 miles an hour once you get to that point the mind
40:26pretty much checks out in terms of giving you good guidance on how to fly the airplane and after that
40:31point uh there's just no recovery we need to climb
40:45you don't know i don't see anything what what is it no no no no 80 seconds from the first sign of
40:58trouble the plane slams into the ground
41:06there's no training that's typically provided to understand how to effectively recover from a situation
41:13such as this the final question for investigators will be the most difficult to answer why did the
41:20inertial reference unit fail in the first place
41:26with more than 9 000 identical units in service around the world the answer is vitally important
41:33the irus have been recovered from the crash site but they're very badly damaged the physical iru was
41:46damaged beyond recognition and we couldn't find out what caused the problem
41:53nothing without the device's memory cards investigators are unable to determine the cause of the failure
42:07we tried in every possible way but we didn't have enough evidence to understand it
42:17what the hell regardless of what caused it the iru's failure should not have caused an accident
42:24there are backup instruments on board for precisely that reason
42:29redundancy is one of the keys to aviation safety because not only do we need redundant pilots
42:35because human beings can fail but we need redundant instruments we we don't want to ever get in a
42:39situation where a single point failure is going to cause you to not be able to fly the airplane safely
42:45in their final report investigators list the pilot's failure to communicate properly the lack of information
42:56provided by the flight instruments about the failure and the effect of negative g loads on the crew as the
43:03main factors causing the accident it's important to communicate really early when you've got a problem
43:13so the other pilot can understand what's going on the investigators recommend that airlines adopt standard
43:21call-outs for pilots to use in similar emergency situations and that manufacturers improve the design of
43:29primary flight displays so that important error messages aren't removed in declutter modes
43:35if you've got more than one crew member and in almost all instances in airline flights you do
43:41you need a procedure for immediately checking with each other and having standard call-outs so that
43:45you're coordinating your actions and coordinating your brains here we had one carbon-based brain making
43:52decisions that were incorrect and starting a slide into an accident sequence because there was no coordination
43:57you're not going to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to be able to
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