Mayday 2025 | The Confusing Autopilot - Doomed Flight 148, Mayday Air Disaster, National Geographic Documentary, Mayday 2025: Air Crash Investigation
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Mayday: Air Disaster is a dramatic non-fiction series that investigates high-profile air disasters to uncover how and why they happened. Mayday: Air Disaster follows survivors, family members of crash victims and transportation safety investigators as they piece together the evidence of the causes of major accidents. So climb into the cockpit for an experience you won't soon forget.
#mayday
#air_disaster
#airline
#crash_on_maoten
#plane_crashs
#maday_episodes
#air_crash_investigation
#mayday #air_crash #mid_air_collision #lose_power #american_airline #explore #trend #fyp
Mayday: Air Disaster is a dramatic non-fiction series that investigates high-profile air disasters to uncover how and why they happened. Mayday: Air Disaster follows survivors, family members of crash victims and transportation safety investigators as they piece together the evidence of the causes of major accidents. So climb into the cockpit for an experience you won't soon forget.
#mayday
#air_disaster
#airline
#crash_on_maoten
#plane_crashs
#maday_episodes
#air_crash_investigation
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NewsTranscript
00:01Just minutes from Strasbourg Airport.
00:05An Airbus A320 slams into a mountain top.
00:18There are survivors.
00:19I'm not panicking because I'm going to burn.
00:23But they are still in grave danger.
00:26It's bitterly cold.
00:28And what they don't realize is that no one knows where they are.
00:34They could be anywhere in there.
00:37Expect this in the jungle or the rainforest,
00:40but not in a highly populated area.
00:45Before investigators can begin searching
00:47for what caused the crash of Air Interflight 148,
00:54they must first find the plane.
00:58They must be in the jungle.
01:03Made it! Made it!
01:04Made it!
01:05Made it!
01:06Made it!
01:07Made it!
01:08Made it!
01:09Made it!
01:10Made it!
01:10Made it!
01:11Made it!
01:11January the 20th, 1992, Air Inter Flight 148 has departed from Lyon, France.
01:38One, two, four, decimal nine or five, thank you.
01:44Captain Christian Hecke and First Officer Joƫl Charubin are experienced pilots with over 12,000 hours of flying time between them.
01:56The flight is a short hop between Lyon in central France and the city of Strasbourg in the mountainous Alsace region.
02:03The French airline Air Inter caters mostly to business travelers and prides itself on being timely.
02:13Crews are motivated to avoid delays, as former Air Inter pilot GĆ©rard Arnoux explains.
02:20We were famous for a very short turnaround. And the faster we flew, the better wages we got.
02:30Have we been flying for 35 minutes yet?
02:3741 minutes.
02:38The crew is flying an Airbus A320, one of the most technologically advanced commercial airplanes in the world.
02:51Even before takeoff, the pilots programmed the autopilot to land on a specific runway in Strasbourg.
02:57The cockpit of the A320 is also very different from other planes. Instead of analog gauges, the pilots look mostly at digital displays.
03:09Strasbourg, good evening. Runway news 05. Transition level 5-0. Wind 040 at 18 knots. Visibility 10 kilometers.
03:26A recording from Strasbourg airport informs the crew of a change in plan. Due to high winds and poor winter weather, they'll have to land on an alternate runway.
03:3705 in service.
03:40Not the one programmed into the autopilot.
03:4305. What sort of wind are they giving us?
03:4718 knots.
03:4818 knots.
03:5018 knots.
03:54Captain Hecke doesn't like the idea of changing runways.
03:58No chance.
04:00He was hoping to use runway 23, an approach that provides the autopilot with a precise navigational fix.
04:07The new runway, runway 05, is surrounded by mountainous terrain that can interrupt radio signals sent to the autopilot.
04:21You know, if we go with the runway 05 procedure, we...
04:26No, no.
04:28Captain Hecke suggests a compromise.
04:32I'm putting back runway 23. Otherwise I couldn't make the ILS interception.
04:38He'll program the autopilot to fly towards runway 23.
04:44But near the airport, the captain will take over the controls and make a visual landing on runway 05.
04:52You're taking 23 then?
04:54Yes!
05:02Ladies and gentlemen, we are commencing our descent. We ask you to please return to your...
05:05Nicholas Skourias is a university graduate student.
05:11It was a quiet day. I was expecting to go to see my girlfriend in Strasbourg. So I was very happy.
05:21Roger 854. Proceed to GTQ, air level 140, contact Reims.
05:30Delta Alpha, Strasbourg.
05:33Yes. We intend to proceed to do an ILS on runway 23, then an indirect for runway 05 after that.
05:42The Strasbourg controller considers the captain's plan.
05:47He warns that there will likely be a delay due to heavy traffic.
05:51Given that we're going to have three take-offs on 05, you risk waiting in the stack at 5,000 feet.
05:55We're not going to mess about like that, descending at full speed.
06:01If they had wound us in the dance, cripes!
06:06Delta Alpha, Strasbourg.
06:08I hear you.
06:10Aware of the captain's frustration, the controller offers assistance.
06:13If you want, I can take you with the radar to lead you to Andlow at 5,000.
06:18Andlow is a navigational point on the approach to runway 05.
06:22It helps pilots align the plane for landing.
06:25Yeah, that's good.
06:27Oh yeah.
06:29Okay then, turn left to heading 230 degrees.
06:33148.
06:35Turn left to heading 230 degrees.
06:38There you are. That will save you some time.
06:40Since runway 05 doesn't allow for a full autopilot approach, the captain must calculate the angle of descent on his own.
06:53That makes 3.3 degrees.
07:033.3 degrees is a normal flight angle that provides a good slope for landing.
07:10Slowly, the good slope.
07:14Ladies and gentlemen, we are continuing our descent.
07:18The flight from Lyon to Strasbourg was quite short.
07:22I think 50 or 45 minutes.
07:25Nothing special. It was very natural and very ordinary.
07:33Turn left, steer 90.
07:34Zero, niner, zero degrees, Delta Alpha.
07:35The controller talks flight 148 through the last turn to align the plane with the runway, now 25 kilometers away.
07:48Then, first officer Cheruban notices the plane is slightly off course.
07:55We're headed inside.
07:59You're inside there.
08:01You should have started with 070.
08:04Yeah.
08:05At least that much.
08:06At least that much.
08:15The controller also notices that the plane is off course.
08:19Air Inter, Delta Alpha.
08:21It has missed aligning itself with ANBLO, the runway's electronic guidepost.
08:24Delta Alpha, you're passing to the right of ANBLO.
08:31Nevertheless, he authorizes the landing.
08:35Authorized for final approach, 05.
08:40Delta Alpha.
08:42The captain initiates the landing sequence.
08:45Flaps towards two.
08:47Flaps towards two.
08:49Flaps at two.
08:51Gail down.
08:59Ladies and gentlemen, we are going to land in a few minutes.
09:06Hekay notices that the plane is traveling too fast, so he extends the speed brakes.
09:11They disrupt airflow over the wing, which helps create more drag to slow the plane.
09:16We have to watch our descent.
09:17We have to watch our descent.
09:20The approach axis.
09:21The first officer is more concerned with their horizontal position in relation to the runway.
09:26Man.
09:27It was 60. Check it out.
09:30But before the crew can adjust their course...
09:34Man!
09:35The crash is catastrophic.
09:36ēal cried.
09:39Vićć receptor 1.
09:44Hey million!
09:45Go, Aliark!
09:47Go, Aliark!
09:50I parle again!
09:52Delta Alpha, your position?
09:54Air Inter, Delta Alpha, Strasbourg.
09:55å¹é¢ eskernombia
09:56Delta Alpha, Strasbourg.
10:03The crash is catastrophic.
10:06The A320 has flown into the side of a mountain.
10:13Delta Alpha, your position.
10:16Flight 148 is no longer on radar,
10:20nor responding to radio contact.
10:23An emergency is declared at Strasbourg airport.
10:26This is the last hit we got.
10:29We're flying about 20 kilometers away from the airport.
10:33Officials need to pinpoint the crash site,
10:36but it's not as easy as it might seem.
10:38The airport's radar is not recorded.
10:41There has been no signal from the plane's emergency beacon,
10:44and surprisingly, no one has reported seeing a plane go down.
10:50It could be anywhere in here.
10:53The proposed search area
10:54covers more than 20 square kilometers of dense forest,
10:57just outside Strasbourg.
10:59the crash of Air Inter flight 148,
11:02with only minor injuries.
11:03The crash of Air Inter flight 148,
11:03with only minor injuries.
11:04Nicholas Correa survives the crash of Air Inter flight 148,
11:11with only minor injuries.
11:12Nicholas Correa survives the crash of Air Inter flight 148,
11:25with only minor injuries.
11:27suitcase in the lockers but there wasn't any lockers I realized that I was alive
11:36it was a crash I saw a fire in front of me and I panicked because I said to
11:42myself I'm going to burn I went to the back of the plane of what remain of the
11:50plane I found some other survivors I was afraid of the explosion I was a panic with
12:05the smell of leaking jet fuel in the air the survivors move away from the burning
12:09plane who stayed together waiting for the first aid but the wait will be longer than
12:20anyone might expect
12:24the first reaction that we have after the crash was okay in half an hour one hour
12:33most and the worst okay the rescue team will be here and it wasn't here
12:42one hour after the crash rescuers still have no idea where the wreckage lies
12:50scurrius and the others now face a new ordeal surviving subzero temperatures in a dark and
13:02isolated forest two and a half hours after flight 148 disappeared from radar near Strasbourg Airport
13:11the missing plane has still not been located amidst growing tension the French Aviation Bureau the BEA sends in its lead investigator
13:23John Paris I immediately called my two main investigators and we organized the the go team and we got prepared to rush to the side as soon as this site was located somewhere
13:38the delay feels like an eternity
13:41a little bit surprisingly long we we can expect this in the jungle or the rain forest but not not exactly in a highly dense populated area like the Strasbourg area
13:55with no help in sight scurrius returns to the wreckage to look for more survivors
14:02I think that some people that die could have survived if the first aid come sooner
14:13nearly a thousand people search for the missing plane but three hours after the crash there's still no sign of it
14:26frustrated scurrius goes looking for help he stumbles into a tv crew trying to find the crash
14:33but with no wreckage in sight they react with skepticism they didn't expect survivors from an airplane crash
14:42they didn't believe that there was one of survival but believe me how was because my face was black
14:53due to the the smoke the curazine and so on the journalists follow him back to the crash site
15:01where they discover eight other survivors
15:05finally the first rescuers arrive the crash site is located near the top of the 2500 foot Monsanto deal
15:2219 kilometers from the runway
15:26they found us after four hours and thirty minutes so it was a mess
15:33a mess I was very very disappointed that at 20 kilometers from Strasbourg and they couldn't find us
15:42a total of 87 passengers and crew have died including the pilot and co-pilot
15:51the survivors begin to tell their stories but no one reports anything that might explain why the plane crashed
15:58I don't know what happened we were landing I lost all consciousness we must have hit the trees
16:09Bob McIntosh an American NTSB investigator arrives at the crash site
16:17the BEA of France recognized the international attention would be on this accident even though it was a domestic accident
16:23he invited a group of international accident investigators to come and participate
16:30the first priority for investigators is to retrieve the plane's black boxes
16:38we have not removed the recorders yet
16:41with the boxes trapped in the burning tail section
16:44any delay could prove costly
16:51we're very anxious about the state of the tape inside
16:55will it be possible to use it
16:57will we get the critical information we need
17:01in France aviation accidents are also investigated by the justice system
17:06Paris S and his team are not allowed access to the site until judicial officials secure the black boxes
17:14I had a visual picture of the gendarme
17:17Aryan transport police standing around keeping us away from the wreckage for a while
17:24and we're very suspicious of these international observers
17:27maybe we should wait
17:29even taking photographs
17:30which was somewhat surprising to us
17:36in a previous crash
17:37the crash of Air France Flight 296 in 1988
17:41investigators waited 10 days before turning the black boxes over to police
17:45rumors persisted that these boxes had been tampered with
17:51this time police are keeping investigators at bay
17:54I can recall seeing the glowing embers and seeing the flight recorder sitting there
18:00and not being able to intervene and say get that thing cooled down as soon as you can
18:10after midnight the boxes are retrieved from the plane and sent for analysis
18:15investigators can only hope it's not too late
18:19there was extremely hot
18:20they looked damaged and they looked burned
18:29in the light of day investigators get some of their first clues from the crash site itself
18:35they discover why the plane's emergency locator beacon didn't send a signal
18:40it was actually destroyed by the impact
18:43the beacon is located inside the cockpit and is designed to start working after a crash
18:51its failure suggests an unusually forceful impact with the ground
18:55we had this first feeling the descent was was abnormally steep
19:00investigators examine the engines to see if they may have stalled before impact
19:03if you find the blades curved and a lot of wood sucked inside the engines then you understand that the engines were working properly
19:19and that's exactly what they find the plane clearly had power yet it plowed steeply into a mountainside without ever sending out a distress signal
19:28investigators are puzzled
19:34they hope that the box which recorded the plane's flight data will help them solve the mystery
19:42those particular recorders had the best survival record of any recorders they were the top of the line as far as survivability is concerned
19:56the black box is designed to survive temperatures up to 1100 degrees Celsius for half an hour
20:01the tape recorder inside is protected by a capsule filled with water
20:12when the recorder heats up the water turns to steam absorbing the energy and actually vents out through a little hole in the crash enclosure
20:20but when the flight data recorder is opened investigators make a troubling discovery
20:25the FDR was totally damaged impossible to read anything from it
20:35it was subjected to heat beyond the 30 minutes the recorder was just never designed to withstand that kind of sustained heat
20:44and so we were very disappointed
20:46there's now only one hope for recovering the plane's flight data a device called a quick access recorder or QAR
20:55maintenance workers use the QAR to access the plane's computers but it also records some flight data
21:02unlike the black boxes the QAR is stored near the cockpit
21:06quick access recorders are not protected at all they're up in the front end of the aircraft
21:13typically in the electronics bay they are generally destroyed just from the impact damage
21:19investigators are encouraged to discover that in this case the QAR has survived
21:24but on closer examination their optimism turns to frustration
21:28the last 20 centimeters of the tape were burned and stretched and were damaged to the point that we couldn't use them into a machine we couldn't read it
21:49investigators are desperate to retrieve the data so they take a chance on an experimental technique known as the garnet technique
21:56a light is shown through a mineral lens made of garnet
22:00use a garnet stone to visualize the magnetic pulses that are actually recorded on the tape
22:09the special lens helps the technicians differentiate between the positive and negative magnetic pulses
22:16which translate as binary digits or bits
22:20there's 768 bits per second
22:23so that's a lot of ones and zeros
22:27you have to be very precise in moving the tape under the lens or the garnet
22:33to make sure you don't miss a bit or read the same bit twice
22:38so it's difficult
22:41analyzing the data is even more painstaking
22:44it took about a day to read a second of recording
22:50any additional second recovered could reveal something that would make a difference
22:58the effort to retrieve all the QAR data could take a month or more
23:08in the meantime the focus of the investigation shifts to the cockpit voice recorder
23:12it was positioned just above the other black box
23:18the cockpit voice recorder which was just inches away but outside of the ashes had air passing over it
23:25survived
23:27runway 23 otherwise
23:29the recording reveals the captain's anxiety early on in the flight
23:32you are taking 23 then?
23:34yes
23:36investigators know that landing on runway 05 requires what's called a non-precision approach
23:43that means pilots receive electronic guidance only on their horizontal position
23:48left and right
23:50they get no guidance when it comes to altitude
23:52the non-precision approach is significantly less accurate
23:58why it's not really difficult but they are less comfortable
24:0205
24:04what sort of wind are they giving us?
24:0618 knots
24:08the non-precision approach increases the demands on the pilots
24:12investigators can also hear that the captain had concerns about landing on runway 05
24:1648 Delta Alpha, you are number one with QAR DMV runway 05
24:29runway 05
24:3110 nautical
24:34that won't work
24:36it's a lot of distress over non-precision approach
24:40wondering what can cause such distress
24:42investigators research pilot training at Air Inter
24:46they find that most pilots did not have extensive training making non-precision landings in the new A320
24:53I think we should have had double the training compared to an older plane
25:01investigators ask the airline for detailed records on the pilots history of runway approaches
25:06they are intrigued by what they discover
25:13Captain Hecke had landed at Strasbourg countless times
25:19but he had never landed an A320 there using a non-precision approach
25:24not going to mess around like that descending at full speed
25:29clearly the captain was uneasy about having to execute a landing he had never made before
25:34I think the captain was worried about making it in at a minimum amount of time
25:40in the minimum amount of delay
25:42have we been flying for 35 minutes yet?
25:45and the co-pilot was worried about not getting in trouble by offending the captain
25:50at least that much
25:52more research into the pilots work history offers yet another revelation
25:56while the two pilots had flown more than 12,000 hours between them
26:02they were both still relatively new to the highly advanced A320
26:07it's 05 in service
26:09the aviation community misunderstood the magnitude of changes brought by the new Airbus A320
26:16the captain had only 162 hours in the A320
26:23and the co-pilot even less, just 61 hours
26:30behind this accident scenario there is an issue of confidence of the crew
26:37in themselves, in the aircraft
26:3918 knots
26:43no chance
26:45they were not prepared really to fly in this kind of condition
26:49they had warned us in advance
26:51Cripes!
26:56Investigators conclude that the crew's training was insufficient
27:00but that alone does not explain the crash
27:04Merde!
27:05No!
27:07No!
27:09No!
27:11No!
27:13No!
27:15Investigators search for other factors in the crash of flight 148
27:19they review the conversations between the crew and air traffic controllers
27:23if you want I can give you radar headings and take you to Andlow at 5,000
27:26yeah
27:29yeah, that's good
27:31the radar vector makes flying easier
27:35the captain was happy because it was reducing his workload
27:38turn left, steer 90
27:42with the controllers assistance
27:45this landing should have been very simple
27:47but when investigators reconstruct the plane's trajectory
27:51using radar information from various stations around the airport
27:54they discover a shocking error
27:56the 0-9-0 heading started here
28:010-9-0 degrees Delta Alpha
28:04but it won't take them to Andlow
28:07last radar vector the controller gave
28:11was incorrect
28:13it sent them
28:15thank you
28:17closer to the mountain
28:18they were
28:20they were
28:22of course
28:24because of following the heading they got from the radar vectoring
28:27they found themselves in this undershoot situation
28:30you're inside there
28:32you should have started with 0-7-0
28:34yeah
28:36investigators are also troubled by the controller's choice of words
28:39when he warned the pilots incorrectly that they were headed to the right
28:43Delta Alpha, you're passing to the right of Andlow
28:46from the pilot's perspective the plane was on the left side of the runway
28:52not the right
28:54it could only add to their confusion
28:56the controller in fact
28:58it was very poor guidance because he didn't employ the usual terminology
29:05and he didn't use the standard phraseology
29:10investigators recommend that controllers use only compass points when giving directions
29:16never the words right and left
29:22the controller's mistakes clearly brought the plane closer to the mountain
29:26turn left
29:28steer 90
29:300-9-0 degrees
29:32but once again investigators feel they don't have the whole story
29:34it's not something totally abnormal to start a descent from this situation
29:45flaps towards two
29:47flaps towards two
29:49it's not what you expected to do everyday but it's not outside the tolerance of the concept of this approach
29:59Gilda
30:03when investigators study the plane's reconstructed flight path
30:07they discover something more alarming than the plane's horizontal misdirection
30:11as it circled the mountain the plane inexplicably entered a dangerously steep and rapid descent
30:17perhaps two and a half times the normal rate of descent
30:23as lethal at that altitude
30:26without the steep descent
30:29they would have cleared the mountain
30:31if the vertical trajectory had been correct
30:36they would have no problem at all
30:37finding the cause of that sudden descent is now key to understanding why 87 people died in one of the most advanced passenger planes on earth
30:50the descent was initiated at 1800 hours
31:0119 minutes and 38 seconds
31:04that
31:06is the point of no return
31:09by studying flight 148's trajectory
31:12investigators determined that the rapid descent began 60 seconds before the crash
31:16there is no indication on tape that the descent was deliberate
31:24how it happened and why the crew didn't notice is a mystery
31:33it should be a no brainer
31:35keeping track of the altitude
31:37the cockpit altimeter gives pilots a constant readout of their altitude
31:42the altimeter that's a very precise instrument
31:45they become very reliable
31:47they're accurate between 5 or 10 feet
31:49ignoring it would be a major error in flying protocol
31:52the recording reveals just one single remark from the crew about their descent
32:01we have to watch our descent
32:04it occurred 16 seconds before the crash
32:07the captain had just extended the speed brakes
32:11the aircraft was accelerating abnormally
32:14the captain started to realize there was something wrong with the descent rate
32:19but the first officer changed the subject
32:22the approach axis
32:24we're hitting the axis a half point off
32:26there
32:28it was 60 check it out
32:29he refocused the captain's attention on the lateral situation rather than the vertical situation which was the main problem of course
32:44and they both failed to recognize the situation
32:48i think they were planning they were going to break out of the clouds so they would be able to see the runway
32:53and they wouldn't need to do the full instrument approach
32:56it was 60 check it out
32:58but the plane never left the clouds
33:00there's an old adage in aviation
33:02rocks have been known to hide out in those clouds
33:05it now seems clear that the crew was not monitoring their altitude closely enough
33:13but a bigger mystery remains
33:16we can only guess why
33:18what caused that deadly descent
33:19after months of work
33:27investigators may finally have the answer
33:30all the available flight data from the damaged quick access recorder has been recovered
33:35we were very anxious to be able to read as much as we could
33:39the data confirms that just before the crash
33:44the plane was speeding towards the ground
33:46at an extremely high rate
33:493300 feet per minute
33:51it also confirms that the angle of descent was dangerously steep
33:55much greater than the 3.3 degrees selected by the captain
34:00decimal three degrees
34:02that's quite a difference
34:07investigators now wonder
34:08did the autopilot malfunction?
34:11did it somehow fail to obey the captain's safe descent angle
34:15and send the plane into a deadly nosedive?
34:18what state was it in before the accident?
34:21unfortunately the flight control unit which houses the autopilot is too badly damaged to provide any definitive answers
34:29we can never demonstrate that this FCU on this aircraft during this flight function properly or not
34:42but then when he returns to studying the flight data
34:45Pariez discovers something that may finally reveal the cause of the crash
34:50he notices a similarity between two key numbers
34:55the plane's vertical speed 3300 feet per minute
34:58and the intended flight path angle 3.3 degrees
35:01coincidence
35:07Pariez uses a flight simulator to test a new theory
35:12can you show me a descent of 3300 feet per minute
35:16he believes that the similarity is no mere coincidence
35:20on the autopilot there are two descent modes
35:25flight path angle
35:26and vertical speed
35:29but they are both displayed on the same window
35:32so 3300 is abbreviated to 33
35:37now show me a flight angle of minus 3.3 degrees
35:43the problem on this aircraft was then the two values were visible on the same window
35:51and controlled by the same knob
35:53three decimal three degrees
35:57minus 3.3 degrees
36:01Pariez strongly suspects that the confusing display tripped up Captain Hecke
36:06so it wouldn't be hard to make that mistake would it?
36:11the confusion is quite easy between the two modes if you don't do it carefully
36:17this
36:19if the captain failed to push the mode selector knob
36:23then entering 33 would not have initiated a safe 3.3 degree angle of descent
36:29instead it would have put the plane into a deadly rate of descent of 3300 feet per minute
36:35two months after the crash another air inter plane enters a dangerously steep descent for the same reason
36:49the crew only discovered the problem when they broke out of the clouds
36:54those pilots also confused the plane's flight path angle with its vertical speed
37:01they were lucky enough to have a much higher cloud base so they could correct the problem
37:08further research reveals an industry-wide problem with the A320
37:12many people confuse these modes especially during training and many of them fell in the trap even after the training
37:22eager to test his new theory
37:26Jean Pariez programs a simulator with all the known data from flight 148
37:32he then inputs the same rate of descent he believes the air inter pilots selected
37:41if Pariez is correct the simulation will end with the plane hitting the mountain
37:47but it doesn't
37:49we are missing something
37:51strangely this didn't lead to a crash
37:53every approach would overfly this obstacle by a significant margin
38:01have we factored in the wind?
38:03we started to work on other alternate hypothesis
38:08let's try again
38:10but initiate the turn sooner
38:12but nothing was really credible
38:16no matter how hard he tries
38:18Pariez cannot simulate the crash
38:21unable to explain why
38:23he turns to the plane's manufacturer for help
38:27thanks for bringing this to my attention
38:29after much research
38:31an Airbus designer comes to Pariez with an explanation about a little known element of the autopilot's design
38:37in emergency situations where the A320 needs to change direction quickly
38:42the autopilot is programmed to reverse the plane's direction at twice the normal rate
38:49the reaction of the autopilot would be much faster
38:53and these cases were typically when you were descending and asking the autopilot to climb
39:00or climbing and asking the autopilot to descend
39:02we immediately went back to the data at the very second at which the descent was commanded by the crew
39:12gear down
39:14Pariez discovers a tragic coincidence
39:19sadly we found that at this very second there was turbulence
39:25there was an ascent
39:27it's very slight but there it is
39:28the momentary turbulence caused the plane to climb slightly
39:34and this led to a positive 600 feet per minute vertical speed for maybe half a second
39:42it was during that same half second that the crew commanded the plane to descend
39:47the autopilot read this as an emergency requiring a blazingly fast descent
39:51that could be it
39:56investigators now contemplate a terrible thought
39:59could a random gust of wind hitting at exactly the wrong split second
40:04have been the difference between life and death
40:08here it comes
40:14and we got the crash
40:16Pariez's theory explains every aspect of the crash
40:19the crew's confusion with the autopilot display
40:243.3 degrees
40:26caused the plane to descend dangerously close to the mountain
40:31turbulence and an obscure safety feature brought it even closer
40:37it was a fatal combination
40:38It's a fascinating lesson about the random dimension of accidents
40:48half a second before half a second later
40:51they wouldn't have the accident
40:54The discovery of a confusing cockpit display
40:58has enormous implications for the entire industry
41:01The flight instrumentation of aircraft like the DC-10, MD-11s, the 7-4s and so on
41:12all the Boeing products and all the commuter products that were using that avionics suite
41:17had this vulnerability about it
41:20Investigators now face a daunting question affecting aircraft safety around the world
41:25If the design of the autopilot interface isn't changed, how many more people could die?
41:40There's mounting evidence that the design of the autopilot interface on Airbus A320s
41:43led the Air Inter pilots to accidentally dial in a dangerous rate of descent
41:513.3 degrees
41:54We felt a need to start the industry to work on this
41:58The plane's manufacturer, Airbus, responds immediately
42:03The main change which was very quickly made was to change the display window
42:09With the new design, if a pilot selects a vertical speed of 3,300
42:15the entire four digit number is displayed
42:19So the confusion between an angle and a vertical speed was no longer possible
42:25For investigators, only one mystery remains
42:32All Airbus A320 jets are designed to be equipped with a safety device
42:36known as a ground proximity warning system
42:40or GPWS
42:43Which is a downward looking single purpose radar
42:46that tells you how high you are above the ground directly beneath the airplane
42:50And if it gets to be too low, it'll set off a warning
42:54Pull up terrain
42:56Pull up
42:58But Captain Hekay
43:00We have to watch our descent
43:01Never received a warning for one very simple reason
43:03Here's A320 didn't have that alarm
43:09Help!
43:24The first question, of course, was why the aircraft was not equipped
43:28So it's not part of the minimum equipment list
43:35The Air and Terror Management had decided
43:38they did not like the false warnings
43:41that had been produced by GPWS equipment
43:46Normally, most planes fly slower than 250 knots
43:52when under 10,000 feet
43:53but we flew at 350 knots
43:56until the final approach
44:01So at those speeds
44:03GPWS was always giving off false alarms
44:06This decision, while legal, prevented the pilots from having one last line of defence
44:19before crashing into the mountain
44:20It's impossible to imagine that the pilot wouldn't have pulled up if he'd heard the alarm
44:27We should have a GPWS on commercial flights
44:33In any case, yes
44:35That's an obvious conclusion
44:38The report discusses
44:40Flight tech...
44:42Investigators conclude that there was no single cause for the crash of Flight 148
44:46The tragedy involved an ill-fated combination of many different weaknesses in the airline industry
44:53We made 35 or so recommendations, including pilot training about the ground proximity warning system and so on
45:09The recommendations lead to sweeping changes
45:13Pilots must now have more A320 training before getting behind the controls
45:19One of the two pilots now need to have at least 300 hours on the plane
45:27They estimated that 300 hours were enough
45:29Another change, the design of a more heat-resistant black box
45:33Another change, the design of a more heat-resistant black box
45:36The FAA did a test, did some studies, what the thermal characteristics of post-crash fires were
45:45Came up with a value of 260 degrees C for 10 hours
45:52Delta Alpha, your position
45:54Air Inter Delta Alpha, Strasbourg
45:57As a result of the Strasbourg crash, the A320 is now a safer plane
46:08You can only get this change if there is what people perceive to be a good reason
46:17And sadly, a good reason is still an accident
46:21An accident
46:22But improved aviation technology is still no substitute for well-trained, well-prepared pilots
46:32There's an old axiom in aviation that you taught early on
46:36That never let an airplane take you somewhere that your brain hasn't visited at least five minutes ahead of time
46:42This is an excellent example of a flight crew that didn't follow that particular axiom
46:46That's a particular axiom