- 15 hours ago
Air Crash Investigation S26E08 Moments From Touchdown
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00:01While a passenger live streams an approach into Pokhara Airport in Nepal.
00:06The plan is to go paragliding with my buddies!
00:14Add power!
00:17Yeti Flight 691 falls from the sky.
00:23What's happening?
00:2972 people are killed.
00:33This was the deadliest crash involving Nepali Airlines ever.
00:41Eyewitness video gives investigators their first lead.
00:46That's at least an 80 degree left bank.
00:52When they analyze the flight data...
00:55Wow.
00:57...they're shocked to discover the engines weren't generating power.
01:01No power, torque indication zero!
01:04There should have been warning lights.
01:06Why didn't they figure it out?
01:08You start to question what was going on in the cockpit.
01:12D-Day, D-Day!
01:15D-Day, D-Day!
01:19D-Day, D-Day!
01:24D-Day, D-Day, D-Day!
01:37Yeti Airlines Flight 691 flies south of the Himalayan mountains in Nepal.
01:48there are 68 passengers on board including Sonu Jaeswal a tourist from India heading
01:56to Pokhara to paraglide with friends poker tower yeti 691 descending through 12,500 feet
02:09captain Kamal Casey is the senior officer and the pilot monitoring instruments on today's flight
02:21he's also a veteran of more than 21,000 flying hours we had absolutely the utmost respect for
02:33captain Kamal Casey as he was a veteran in the Nepalese skies and he was quite a humble and
02:39knowledgeable guy as well it's very clear we'll be good for visual landing flying the plane from
02:49the left-hand seat is captain Anju Katawada she's flown more than 6,000 hours Captain Katawada has a very
02:59special history her husband he was a pilot to the same company he was a first officer on the twin
03:06out there and it crashed and he died some years earlier Katawada decided to take up flying to
03:14honor his spirit so she become a pilot 8,500 feet while captain Katawada is an experienced commercial
03:25pilot she has only 186 hours on the ATR 72
03:39the ATR 72 is a turboprop twin-engine aircraft it's a high-wing aircraft it's a very stable predictable and
03:50logical aircraft and it's a very good to fly here in the mountains and hilly regions of Nepal
04:01today's flight is a short 25-minute hop from Kathmandu to the tourist city of Pokhara
04:12yeti 691 expect to land on one to 15 miles from the airport yeti flight 691 is cleared for the
04:25approach
04:28hey everyone exciting times as we're headed to Pokhara's new airport Sonu Jaiswal is live streaming from the cabin
04:35the plan is to go paragliding in the Himalayan foothills with my buddies
04:47captain Katawada programs a heading for the approach to runway 12
04:56you are in between the runway and the mountains so you need to be very very precise with your handling
05:04skills of the aircraft ok visual visual ok visual the pilots monitor their position carefully keeping
05:17the plane clear of the mountains
05:22yeti airline 691 in sight report final runway 12
05:27call you on final for runway 12 yeti airlines 691
05:35you're down
05:39less than two minutes from the airport the pilots configure the plane for landing
05:45ok from here you can go manual ok standby
05:52disconnect
05:54captain Katawada disconnects the autopilot then begins the first of two crucial turns to line up with the runway
06:11okay
06:12okay flaps 30
06:14flaps 30
06:17continue descent
06:19okay
06:23one minute from touchdown the pilots run through the pre-landing checklist
06:28okay landing gear down three green
06:31flaps
06:3230
06:37in the cabin Sonu Jaiswal continues live streaming
06:42we're getting pretty close now
06:47as the flight gets closer to the ground
06:49the landing seems trouble free
06:58but seconds from the runway captain Casey realizes there's a critical problem with the engines
07:04there's no power
07:07there's no power
07:11when there's no power
07:13that means they have very limited time
07:15at that altitude
07:17they need to react quickly
07:20add power
07:22captain katawada tries to power up
07:26but the engines aren't producing any thrust
07:30400 feet above the ground
07:32the pilots face a critical situation
07:39in the tower the controller doesn't know that flight 691 is in any trouble
07:44yeti 691 runway 12
07:48clear to land
07:49there's no power no power
07:52add power
07:56captain katawada pushes the throttles to the limit
08:04there's no torque
08:05okay give it to me
08:09the more senior captain takes control
08:188691
08:22200
08:25flight 691 is stalling
08:35while Sonu Jaiswal live streams the unfolding disaster
08:44what's happening
08:52does
09:19is
09:20yeti flight 691 has
09:22crashed in one of the worst possible places the city river runs near to the airport through a
09:31huge cause that's where the plane crashed the plane was completely destroyed in the impact
09:42there was a huge flame burning
09:47there was no possibility to find any survivor
09:54the bodies of 71 of the 72 passengers and crew are eventually found and identified including both
10:03pilots this was the deadliest grass involving nepali airlines ever what could have caused a commercial
10:16airliner to drop out of the sky just seconds before landing
10:29when investigators arrive at the crash site of yeti flight 691 they face a devastating scene
10:40the records were scattered all over the place the first impact was before the river where the
10:47parts of the left wing was detached
10:50some parts were located on the bottom of the river gods and rest of the pathway at the saddle river
11:03under the supervision of nepali investigators the wreckage along with the black boxes and central
11:10processing card from the plane's computer are sent for analysis to labs in france and singapore
11:18it's really not uncommon in an accident investigation to have to send something out for closer investigation
11:33nepali investigators wonder about flight 691's orientation when it hit the ground
11:41looks like this is from the first point of impact
11:45that's a flap from the left wing and an aileron tip
11:52so the left wing must have hit the ground first
11:58the plane crashes wing down what that suggests to investigators is that the plane crashed out of
12:05control you would never intend to have it be that way you'd always try and level it out and crash
12:10as close to a regular attitude as you can
12:15maybe the plane stalled
12:18you may be right check this out
12:29it's gone viral
12:36a witness had filmed the plane during the final moment of the flight
12:42it appears that the left wing lost lift and dipped severely
12:49that's at least an 80 degree left bank
12:58sure looks like a stall to me
13:04when you see evidence that looks like a stall you immediately start questioning what could have
13:10led to that and you go back to what's going on during that approach
13:21this is not an easy approach
13:25they'd have to fly between the runway and the mountain and make two left turns before lining up with runway
13:31one two
13:33and this is where the plane crashed
13:36and just before the crash they were beginning their final left turn
13:42did the pilots bank too far during one of the turns and stall
13:49they would have had to go from zero to an 80 degree bank in a few seconds
13:54yeah
13:57it suggests there was a problem with the plane
14:03you might want to focus and see if there's any smoking guns in the maintenance records
14:08if there was anything wrong that somebody knew about maybe they tried to fix it and it didn't get fixed
14:16i've got maintenance records
14:23investigators go through the plane's records in search of any gaps in maintenance or inspections
14:32i'm not seeing anything everything checks out
14:39maybe the controller knows something
14:44yeah the air traffic controller may have heard something in their conversation with the pilots
14:49picked up something that isn't really evident from the tape
14:56did you have visual contact with the aircraft
15:04did you see or hear anything suggesting a problem with the plane
15:08no um i was flying normally when i had visuals with it it was just out of sight right before
15:14the crash
15:17then i heard it
15:21explosion
15:40did the pilots say anything suggesting the problem with the plane
15:44nope not much
15:48okay thank you
15:52so do you know what happened
15:59not yet
16:07in the early stages you'd want to look at anything witnesses might have to say anybody who might have
16:12seen heard or otherwise notice the crash the controller offers little insight into why the plane stall
16:21then a witness to the accident comes forward there that's where you saw the plane
16:30he had the credibility because he was an engineer
16:34and you said that you saw the propeller spitting just before the crash
16:42when you see a propeller rotating it means it was very slow otherwise you cannot see it moving
16:48okay thank you
16:52the slow rotation of the propellers could indicate there was a problem with the engines that drive them
17:01quick update sounds like engine failure
17:06we need to talk to the french about their engine analysis
17:14hello
17:15hello
17:18nepali investigators now joined the team from france to examine the wreckage of yeti flight 691
17:26engines are badly damaged
17:29can't tell if they failed in flight
17:35most of the engines were consumed by fire
17:38so they couldn't learn definitively whether they were producing power
17:46look at that prop
17:50investigators notice something telling on a propeller hub
17:57looks feathered
18:07when propellers are feathered their edges face forward and cannot produce thrust
18:15it's like putting your car in neutral position
18:18you can push on the gas as much as you want but nothing is going to happen
18:27it's actually stuck in a feather position
18:31okay
18:39this one moves freely but it could have moved on impact
18:48this one is stuck too
18:52so two of them were in the feathered position when they hit the ground
19:00normally propellers are feathered on the ground after shutdown
19:04that prevents them from spinning in the wind and damaging the engine
19:08there is however one exception
19:12an automatic feathering unit will feather that propeller immediately as soon as an engine failure
19:17is detected perhaps faster than the pilot can do it
19:23were the props feathered automatically in flight due to engine failure
19:28investigators download the data from flight 691's multi-function computer to find out
19:35the multi-function computer stores information about the automatic feathering unit in its memory
19:42they're going to be able to learn whether the auto feather unit feathered one engine
19:48or both engines
19:59it never activated
20:02if you learn that the auto feather system didn't feather the propellers that immediately raises the
20:08question who or what did
20:13were the propellers feathered manually investigators consider a crucial piece of wreckage recovered from
20:20the scene the central control pedestal the central pedestal is located between the pilots
20:27and here you have the power levers you have the flaps lever and the other condition levers which controls the
20:35propellers
20:37the flaps are stuck at 30 that's where they should be for landing
20:45condition levers are moving freely
20:49doesn't tell us much
20:54hmm look at this
21:02witness mark
21:05you're looking for witness marks the marks that one aircraft component makes against another
21:11at the time of impact
21:13and those marks will suggest in the case of the central control pedestal where the controls were positioned at impact
21:23the witness mark suggests that the pilots could have put the left lever in the feathered position
21:31maybe some other debris caused the witness mark
21:34there's no witness mark for the right condition lever
21:40were the propellers feathered by the pilots
21:44or did the witness marks occur on impact
21:47we're going to need the flight data recorder download to settle this
21:55the flight data recorder doesn't record the propeller blade angle
22:00but it does record certain parameters that let investigators infer whether the propellers were feathered and if so when
22:26they find evidence that the pilots feathered the props one minute before the crash
22:34when the propellers are feathered the torque drops and the propellers rpm speed drops
22:41that's what the witness was able to see when he reported spotting the individual propeller blades
22:48how did they make that mistake
22:56what was going on in the pilot's mind
23:00what was going on in the cockpit
23:03what's happening
23:16pick it up 24 minutes into the flight right before the propellers were feathered
23:23investigators listen to the cockpit voice recording from yeti airlines flight 691
23:29to understand why the pilots feathered their propellers when they did
23:34okay from here you can go manual
23:36okay stand by
23:40disconnect
23:43okay flaps 30
23:46flaps 30
23:49continue descent
23:51okay
23:52stop
23:53samson
23:54where are we at here
23:57time is 10 56 35
24:04according to the fdr
24:07the flaps did not move to 30 at this point
24:11but this is when the props were feathered
24:17the fdr shows that when the pilot flying commanded flaps 30
24:21the flaps didn't move
24:24but at the same moment the prop rpm decreased and torque went to zero
24:30the pilot has pretty obviously feathered the engines instead of moving the flaps
24:44they must have mixed up the flap levers with the condition levers
24:48and captain casey was the pilot monitoring
24:54how could a captain make that mistake
25:02in most elan accidents pilot error is a factor that can be because of inadequate training experience
25:12it can be because of too little rest
25:17but there can also be other factors impairing their decisions
25:22here you go
25:27the team reviews results from the pilot's toxicology tests
25:34nothing on captain katiwata
25:42same with captain casey
25:47maybe they weren't adequately rested
25:52according to the airline's records both pilot schedules were within guidelines
25:57suggesting adequate rest
25:59and their medical certificates are current
26:03they conclude that something other than impaired judgment caused the pilots to feather the props by mistake
26:10at this point you'd have to wonder what might have been going on in the cockpit
26:14that would lead him to be distracted into setting the propellers to feather instead of setting the flaps for landing
26:23did the location of the condition levers on the pedestal play a part in the captain's error
26:30they examine an atr 72 pedestal
26:35i reach over for the flaps
26:39but i put my hand on the condition lever instead
26:47the flap lever and the condition lever are very close together on the pedestal
26:53i want to move the flaps to the 30 degree position
26:58but instead i move the condition lever to feathered
27:08the flap and condition levers have the same range of motion and stop in similar positions
27:16it's not a stretch that they could have mixed up the levers
27:20and don't forget captain casey was where i'm sitting
27:26right
27:31mercy and memory is very important for a pilot because you can do sequences without being conscious about it
27:39but when you move to another seat on the other side certainly that flow is disturbed because now you have
27:46to use the opposite hand
27:50oh that feels a lot less natural
27:55and much easier to mix up
28:01okay flaps 30
28:04flaps 30
28:07continue descent
28:11the pilot monitoring move the condition levers instead of the flap lever
28:16that should be impossible but it has happened before
28:21i once asked for flaps and the pilot monitoring selected the gear down
28:27and those layers are far apart
28:32still it's hard to imagine looking at these levers
28:36that you'd get them confused
28:39true
28:46maybe he wasn't looking at them
28:52why would an experienced captain not check which levers he was moving
29:02okay
29:03visual visual
29:04okay visual
29:07investigators return to the voice recording of yeti airlines flight 691
29:12to determine if the captain's attention was elsewhere when he selected the wrong levers
29:17okay make sure you stay between the mountains and the runway
29:21they revisit the moment just before the propellers were feathered
29:25keep your power nose up
29:28keep visual with the tower
29:29keep visual with the tower don't go too far
29:31okay copy that
29:35okay stop for a second
29:39he's giving her a lot of instructions
29:43maybe that's the distraction
29:46but she's a very experienced pilot so why is he doing that
29:52when you're giving instruction that's an added mental stress it's an added cognitive load
29:59it's very distracting
30:01let's start from the top
30:04poker tower
30:06yeti airline 691
30:08yeti airline 691
30:12tower yeti 691 descending through 12 500 feet
30:18roger yeti 691 12 500 feet
30:23expect to land on runway 30
30:26runway 30 yeti 691
30:31they discover that flight 691 was initially cleared to land on a different runway runway 30
30:40but eight minutes later there's a change of plan
30:43if traffic permits let's land on runway 12
30:47then you'll be approved for runway 12 without any instructor pilot supervision
30:52okay runway 12
30:55not only is he monitoring the flight
30:58he's approving her to land at pohra's new airport
31:03investigators discover captain casey was instructing pilots on how to land on both runways at the new airport
31:12i flew with captain kamal casey just two days before for my good qualification into pohra international airport
31:21but why runway 12
31:26you'll be approved to land in both directions
31:29copy that
31:36okay stop it
31:37so captain katewada is cleared for runway 30
31:43and captain casey decides much later in the game he's approving her for runway 12
31:51captain katewada had landed on runway 30 but never won two
31:57runway 30 is a straight-in approach
32:04and runway one two you follow a narrow track next to the mountains
32:09you turn left twice to line up with the runway
32:12so captain casey put captain katewada on a more difficult landing
32:23runway one two was a challenging approach for a pilot with just 185 hours on the area
32:30did captain casey properly prepare captain katewada for the difficult approach to runway one two
32:39the best way to prepare a pilot for such an approach would be to do a proper briefing
32:46maybe they have photos videos simulator training if available
32:54investigators examine captain katewada's training records
33:00she spent no time in the simulator training on runway one two
33:04what about a formal briefing
33:07there's no documentation related to training on one two
33:11i've got captain casey's flight history
33:15was captain casey even qualified to train others for landing on runway one two
33:21turns out he had only landed on one two twice
33:26a bit of experience but not enough
33:33because of his low experience and also katewada's low experience on the aircraft i find that a bit strange
33:43i wonder if it's even possible to do a stabilized visual landing using that approach
33:57a stabilized visual approach is one that's conducted with the runway in sight
34:03at a normal rate of descent with landing flaps and landing gear down at the proper airspeed
34:11and with all checklists completed by a certain point
34:15there's just over one mile between the completion of the last turn and the runway
34:23that's going to give you just over 30 seconds from lining up to landing it's very tight
34:35official landing can increase the workload because they have to make tiny adjustments all the way
34:40through the pattern let's see how they handle the workload
34:47okay make sure you stay between the mountains and the runway
34:51to understand how the pilots dealt with the final approach to runway one two
34:55investigators return to the cvr keep your power nose up keep visual with the tower
35:04don't go too far okay copy that remember you need to make an early turn here
35:12okay a beam tower gear down gear down
35:21can i fly it manually wait wait not yet keep going straight after flaps 30 then you're good to go
35:31manual
35:32hold on captain casey is so focused on pointing out landmarks outside the cockpit
35:39he's not paying attention to what's happening inside the cockpit
35:45it's normal to let the less experienced pilot fly the aircraft and the most experienced
35:50pilot do the analysis okay flaps 30. flaps 30.
36:02continue to send okay
36:09you probably didn't even look down to see what lever he was moving
36:14but there was still an opportunity to catch the mistake when they do the landing checklist
36:23the before landing checklist was an opportunity for him to look down at that control pedestal and see
36:30that he had moved the condition levers into feather i'm almost certain they could have recovered right
36:36up until the last few seconds did the pilots failure to follow their checklist ultimately determine their fate
36:50nepali investigators continue listening to the cvr of flight 691
36:56to learn whether the pilots followed the proper procedures before landing before landing checklist
37:07okay landing gear down three green flaps 30.
37:13right captain kariwata said the flaps are at 30 but according to the fdr they're still set at 15.
37:22neither pilot checked the flap settings
37:27if captain kc saw that the flaps were not at 30 he may have realized he had moved the wrong
37:34lever
37:35power management take off tlu low speed icing aoa check external lights on on complete
37:48they rushed the before landing checklist was done very fast like bam bam bam bam bam bam
37:56and i doubt any of them looked at the flap setting they just answered by memory oh and with the
38:04props feathered
38:06there should have been warning lights why didn't they figure it out
38:20when the propellers are feathered they're no longer providing power to the generators
38:27an oral and visual elect warning alerts the pilots that they're losing electrical power
38:33what is this
38:36elect is on cap
38:40the elect light comes on to warn the pilots hey you've got a big electrical problem
38:46checked checked
38:48someone clicked off the warning they clicked off the warning without figuring out why it even came on
38:57it's hard to tell why captain kamal kc responded checked to the electrical light
39:04check
39:05would you pull out a quick reference handbook and start working a long electrical failure procedure
39:10or would you recognize hey i'm landing in less than 60 seconds let's just bring the plane in and deal
39:16with the problem on the ground we just continue right yes continue turn
39:27what's that click about
39:34fdr data shows this is where the flaps goes to 30. so he notices the flap is not set at
39:4030 and corrects it
39:49and with so much workload all he sees is the flap lever and doesn't notice that the propellers are feathered
39:57when your workload increases you get tunnel vision and you see less that makes it very difficult because
40:05now you only focus on one thing
40:09okay but why doesn't he figure it out when the engines have dropped to idle
40:19seconds from the runway captain casey realizes there's an issue with the engines
40:24there's no power there's no power add power
40:32even though the pilots see the engines are at idle they are still unaware that the propellers are feathered
40:39there's no power no power add power
40:44there's no torque okay give it to me
40:49there's no power
40:50in desperation captain casey takes control of the plane you're landing sir
40:55no power torque indication zero
40:58two hundred
41:01eighty six nine one
41:04what's happening
41:18he decided to fly the plane rather than try to diagnose the problem
41:32one single glance around the cockpit could have told him that he had feathered the propellers
41:45the final report of the nepali accident investigation commission concludes that the most probable cause of the accident
41:53was the inadvertent movement of both condition levers to the feathered position in flight
42:01what strikes me about this is that it was a very normal situation
42:05the only thing that went between success and failure was the slip of a hand
42:16the proximity to terrain and sharp turn required to land on runway one two
42:22before landing checklist combined with a high workload and a lack of appropriate training
42:28all contributed to the crash
42:33after the accident yeti airlines tests the approach in the simulator with their pilots
42:40most of our pilots were not able to land on runway one two
42:45either they were high on approach or they were fast on speed
42:52yeti airlines stops flying into runway one two
42:56until they are able to establish a safe visual procedure and retrain their pilots
43:02the commission recommends that the civil aviation authority of nepal
43:07ensures that a stabilized flight path is approved before allowing commercial operations at a new airport
43:18after the accident the victims of yeti air flight 691
43:22are mourned by a nation and fellow pilots remember their colleagues
43:30oh captain kamal casey i just want to remember him when he was alive and he was there with us
43:39the captain captain kathyboda i respected her a lot
43:47she will be remembered as an elder sister and there is going to be always a void in the airlines
43:56that
43:57she is not there anymore
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