- vor 14 Minuten
On 15 January 2023, Yeti Airlines Flight 691 stalls and crashes into a gorge near the Seti Gandaki River during final approach to Pokhara International Airport, killing all 72 people on board. It was later determined that the pilots accidentally feathered the aircraft's propellers.
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LernenTranskript
00:03While a passenger livestreams an approach into Pokhara Airport in Nepal...
00:09The plan is to go paragliding with my buddies!
00:16Add power!
00:19Yeti Flight 691 falls from the sky.
00:25What's happening?!
00:3172 people are killed.
00:34This was the deadliest crash involving Nepali Airlines ever.
00:43Eyewitness video gives investigators their first lead.
00:47That's at least an 80-degree left bank.
00:53When they analyze the flight data...
00:56Wow!
00:57They're shocked to discover the engines weren't generating power.
01:02No 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.
01:22Yeti Airlines Flight 691 flies south of the Himalayan mountains...
01:36Yeti Airlines Flight 691 flies south of the Himalayan mountains...
01:41...in Nepal.
01:47There are 68 passengers on board...
01:50...including Sonu Jaiswal, a tourist from India...
01:53...heading to Pokhara to paraglide with friends.
02:00Pokhara Tower, Yeti 691...
02:02...descending through 12,500 feet.
02:07Captain Kamal Casey is the senior officer...
02:10...and the pilot monitoring instruments on today's flight.
02:13Roger, Yeti 691.
02:1512,500 feet.
02:18He's also a veteran of more than 21,000 flying hours.
02:25We had absolutely the utmost respect for Captain Kamal Casey...
02:30...as he was a veteran in the Nipoli skies...
02:34...and he was quite a humble and knowledgeable guy as well.
02:39It's very clear.
02:41We'll be good for visual landing.
02:44Flying the plane from the left-hand seat...
02:47...is Captain Anju Katawada.
02:49She's flown more than 6,000 hours.
02:53Captain Katawada has a very special history.
02:57Her husband, he was a pilot to the same company.
03:00He was a first officer on the three-note there...
03:02...and it crashed and he died some years earlier.
03:05Katawada decided to take up flying to honor his spirit...
03:11...so she'd become a pilot.
03:148,500 feet.
03:16While Captain Katawada is an experienced commercial pilot...
03:20...she has only 186 hours on the ATR-72.
03:33The ATR-72 is a turboprop twin-engine aircraft.
03:38It's a high-wing aircraft.
03:41It's a very stable, predictable and logical aircraft.
03:45And it's very good to fly here in the mountains and hilly regions of Nepal.
03:54Today's flight is a short 25-minute hop from Kathmandu...
03:58...to the tourist city of Pokhara.
04:05Yeti 691, expect to land on 1-2.
04:09Broadway 1-2, Yeti 691.
04:1315 miles from the airport.
04:15Yeti flight 691 is cleared for the approach.
04:20Hey everyone, exciting times as we're headed to Pokhara's new airport.
04:24Sonu Jaiswal is live streaming from the cabin.
04:27The plan is to go paragliding in the Himalayan foothills...
04:30...with my buddies!
04:363-1-0.
04:38Captain Katawada programs a heading for the approach to runway 1-2.
04:47You are in between the runway and the mountains.
04:51So you need to be very, very precise with your handling skills of the aircraft.
04:59Okay, visual, visual.
05:01Okay, visual, visual.
05:04The pilots monitor their position carefully, keeping the plane clear of the mountains.
05:12Yeti Airlines 691 in sight. Report final, runway 1-2.
05:17Call you on final for runway 1-2. Yeti Airlines 691.
05:24Gear down.
05:28Less than two minutes from the airport, the pilots configure the plane for landing.
05:34Okay, from here you can go manual.
05:36Okay, standby.
05:41Disconnect.
05:43Captain Katawada disconnects the autopilot, then begins the first of two crucial turns to line up with the runway.
05:59Okay, flaps 30.
06:01Flaps 30.
06:02Flaps 30.
06:04Continue descent.
06:06Okay.
06:10One minute from touchdown, the pilots run through the pre-landing checklist.
06:16Okay, landing gear.
06:17Down three green.
06:19Flaps?
06:1930.
06:24In the cabin, Sonu Jaiswal continues live streaming.
06:29We're getting pretty close now.
06:33As the flight gets closer to the ground, the landing seems trouble-free.
06:44But seconds from the runway, Captain Casey realizes there's a critical problem with the engines.
06:50There's no power.
06:53There's no power.
06:56When there's no power, that means they have very limited time at that altitude.
07:01They need to react quickly.
07:05Add power.
07:07Captain Katawada tries to power up, but the engines aren't producing any thrust.
07:15400 feet above the ground, the pilots face a critical situation.
07:23In the tower, the controller doesn't know that flight 691 is in any trouble.
07:28Yeti 691, runway 12.
07:31Clear to land.
07:33There's no power. No power.
07:36Add power.
07:40Captain Katawada pushes the throttles to the limit.
07:47There's no torque.
07:49There's no torque.
07:49Okay, give it to me.
07:51The more senior captain takes control.
08:008691.
08:04200.
08:068691.
08:08Flight 691 is stalling.
08:16While Sonu Jaesua live streams the unfolding disaster.
08:25What's happening?
08:27What's happening?
08:34What's happening?
08:36What's happening?
08:40What's happening?
08:45That's great.
09:00Yeti Flight 691 has crashed in one of the worst possible places.
09:06The Seti River runs near to the airport through a huge gorge, that's where the plane crashed.
09:16The plane was completely destroyed in the impact. There was a huge flame burning.
09:26There was no possibility to find any survivor.
09:33The bodies of 71 of the 72 passengers and crew are eventually found and identified, including both pilots.
09:44This was the deadliest crash involving Nepali Airlines ever.
09:52What could have caused a commercial airliner to drop out of the sky just seconds before landing?
10:06When investigators arrive at the crash site of Yeti Flight 691, they face a devastating scene.
10:16The wreckage was scattered all over the place.
10:21The first impact was before the river, where the parts of the left wing was detached.
10:27Some parts were located on the bottom of the river gorge, and the rest of the parts were at the
10:32side of the river.
10:39Under the supervision of Nepali investigators, the wreckage, along with the black boxes and central processing card from the plane's
10:47computer,
10:48are sent for analysis to labs in France and Singapore.
10:54It's really not uncommon in an accident investigation to have to send something out for closer investigation.
11:08Nepali investigators wonder about Flight 691's orientation when it hit the ground.
11:15Looks like this is from the first point of impact.
11:19That's a flap from the left wing and an aileron tip.
11:25So the left wing must have hit the ground first.
11:32The plane crashes wing down.
11:34What that suggests to investigators is that the plane crashed out of control.
11:39You would never intend to have it be that way.
11:42You'd always try and level it out and crash as close to a regular attitude as you can.
11:47Maybe the plane's stalled.
11:51You may be right.
11:53Check this out.
12:01It's gone viral.
12:08A witness had filmed the plane during the final moment of the flight.
12:14It appears that the left wing lost lift and dipped severely.
12:20That's at least an 80 degree left bank.
12:29It sure looks like a stall to me.
12:35When you see evidence that looks like a stall, you immediately start questioning what could have led to that.
12:41And you go back to what's going on during that approach.
12:51This is not an easy approach.
12:55They'd have to fly between the runway and the mountain
12:58and make two left turns before lining up with runway one-two.
13:03And this is where the plane crashed.
13:05And just before the crash, they were beginning their final left turn.
13:11Did the pilots bank too far during one of the turns and stall?
13:18They would have had to go from zero to an 80 degree bank in a few seconds.
13:23Yeah.
13:26It suggests there was a problem with the plane.
13:29Yeah.
13:32You might want to focus and see if there's any smoking guns in the maintenance records.
13:36If there was anything wrong that somebody knew about, maybe they tried to fix it and it didn't get fixed.
13:43I've got maintenance records.
13:51Investigators go through the plane's records in search of any gaps in maintenance or inspections.
13:59I'm not seeing anything.
14:02Everything checks out.
14:06Maybe the controller knows something.
14:09Yeah.
14:11The air traffic controller may have heard something in their conversation with the pilots,
14:16picked up something that isn't really evident from the tape.
14:23Did you have visual contact with the aircraft?
14:30Did you see or hear anything suggesting a problem with the plane?
14:34No.
14:35I was flying normally when I had visuals with it.
14:37It was just out of sight right before the crash.
14:42Then I heard it.
14:46Explosion.
15:04Did the pilots say anything suggesting the problem with the plane?
15:08Nope.
15:09Not much.
15:12Okay.
15:15So...
15:17Do you know what happened?
15:23Oh, yeah.
15:30In the early stages, you'd want to look at anything witnesses might have to say,
15:35anybody who might have seen, heard, or otherwise noticed the crash.
15:40The controller offers little insight into why the plane stall.
15:44Then a witness to the accident comes forward.
15:47There?
15:48That's where you saw the plane?
15:52He had the credibility because he was an engineer.
15:56And you said that you saw the propeller spitting just before the crash?
16:04When you see a propeller rotating, it means it moves very slow, otherwise you cannot see it moving.
16:10Okay.
16:13The slow rotation of the propellers could indicate there was a problem with the engines that drive them.
16:22Quick update.
16:24Sounds like engine failure.
16:26Yeah.
16:27We need to talk to the French about their engine analysis.
16:34Hello?
16:38Nepali investigators now joined the team from France to examine the wreckage of Yeti Flight 691.
16:46Engines are badly damaged.
16:49Can't tell if they failed in flight.
16:54Most of the engines were consumed by fire, so they couldn't learn definitively whether they were producing power.
17:04Look at that prop.
17:09Investigators notice something telling on a propeller hub.
17:15Looks feathered.
17:25When propellers are feathered, their edges face forward and cannot produce thrust.
17:32It's like putting your car in neutral position.
17:35You can push on the gas as much as you want, but nothing is going to happen.
17:44It's actually stuck in a feather position.
17:48Okay.
17:55This one moves freely, but it could have moved on impact.
18:04This one is stuck too.
18:08So, two of them were in the feathered position when they hit the ground.
18:16Normally, propellers are feathered on the ground after shutdown.
18:19That prevents them from spinning in the wind and damaging the engine.
18:24There is, however, one exception.
18:27An automatic feathering unit will feather that propeller immediately as soon as an engine failure is detected.
18:33Perhaps faster than the pilot can do it.
18:38Were the props feathered automatically in flight due to engine failure?
18:43Investigators download the data from Flight 691's multi-function computer to find out.
18:49The multi-function computer stores information about the automatic feathering unit in its memory.
18:56They're going to be able to learn whether the auto feathering unit feathered one engine or both engines.
19:12It never activated.
19:16If you learn that the auto feather system didn't feather the propellers, that immediately raises the question, who or what
19:23did?
19:26Were the propellers feathered manually?
19:29Investigators consider a crucial piece of wreckage recovered from the scene, the central control pedestal.
19:36The central pedestal is located between the pilots.
19:40And here you have the power levers, the other flaps lever, and the other condition levers, which controls the propellers.
19:49The flaps are stuck at 30.
19:52That's where they should be for landing.
19:57Condition levers are moving freely.
20:00It doesn't tell us much.
20:04Hmm.
20:05Look at this.
20:13Witness mark.
20:16You're looking for witness marks, the marks that one aircraft component makes against another at the time of impact.
20:22And those marks will suggest, in the case of the central control pedestal, where the controls were positioned at impact.
20:33The witness mark suggests that the pilots could have put the left lever in the feathered position.
20:40Maybe some other debris caused the witness mark.
20:43There's no witness mark for the right condition lever.
20:50Were the propellers feathered by the pilots?
20:53Or did the witness marks occur on impact?
20:56We're going to need the flight data recorder download to settle this.
21:04The flight data recorder doesn't record the propeller blade angle.
21:09But it does record certain parameters that let investigators infer whether the propellers were feathered, and if so.
21:15We know when.
21:24Wow.
21:27The torque and propeller speed drop at the same moment.
21:31But are the engines at idle?
21:34They find evidence that the pilots feathered the props one minute before the crash.
21:41When the propellers are feathered, the torque drops, and the propeller's RPM speed drops.
21:48That's what the witness was able to see when he reported spotting the individual propeller blades.
21:54How did they make that mistake?
22:02What was going on in the pilot's mind?
22:06What was going on in the cockpit?
22:08What's happening?
22:21Pick it up 24 minutes into the flight, right before the propellers were feathered.
22:28Investigators listened to the cockpit voice recording from Yeti Airlines Flight 691 to understand why the pilots feathered their propellers
22:37when they did.
22:38Okay, from here you can go manual.
22:41Okay, stand by.
22:45Disconnect.
22:48Okay, flaps 30?
22:50Flaps 30.
22:53Continue descent.
22:55Okay.
22:57Stop, stop.
22:58Where are we at here?
23:01Time is 10 56 35.
23:07According to the FDR, the flaps did not move to 30 at this point.
23:14But this is when the props were feathered.
23:20The FDR shows that when the pilot flying commanded flaps 30, the flaps didn't move.
23:26But at the same moment, the prop RPM decreased and torque went to zero.
23:33The pilot has pretty obviously feathered the engines instead of moving the flaps.
23:45They must have mixed up the flap levers with the condition levers.
23:50And Captain Casey was the pilot monitoring.
23:56How could a captain make that mistake?
24:03In most airline accidents, pilot error is a factor.
24:08That can be because of inadequate training, experience.
24:13It can be because of too little rest.
24:17But there can also be other factors impairing their decisions.
24:21Here you go.
24:27The team reviews results from the pilot's toxicology tests.
24:34Nothing on Captain Katiwata.
24:41Same with Captain Casey.
24:46Maybe they weren't adequately rested.
24:51According to the airline's records, both pilot schedules were within guidelines, suggesting adequate rest.
24:58And their medical certificates are current.
25:01They conclude that something other than impaired judgment caused the pilots to feather the props by mistake.
25:09At this point, you'd have to wonder what might have been going on in the cockpit that would lead him
25:13to be distracted
25:15into setting the propellers to feather instead of setting the flaps for landing.
25:21Did the location of the condition levers on the pedestal play a part in the captain's error?
25:28They examine an ATR-72 pedestal.
25:32I reach over for the flaps, but I put my hand on the condition lever instead.
25:43The flap lever and the condition lever are very close together on the pedestal.
25:49I want to move the flaps to the 30 degree position.
25:55But instead, I move the condition lever to feathered.
26:03The flap and condition levers have the same range of motion and stop in similar positions.
26:12It's not a stretch that they could have mixed up the levers.
26:15And don't forget, Captain Casey was where I'm sitting.
26:21Right.
26:26Mercer memory is very important for a pilot because you can do sequences without being conscious about it.
26:34But when you move to another seat on the other side, certainly that flow is disturbed,
26:39because now you have to use the opposite hand.
26:44Oh, that feels a lot less natural.
26:49And much easier to mix up.
26:55Okay. Flaps 30.
26:58Flaps 30.
27:01Continue to sense.
27:04The pilot monitoring move the condition levers instead of the flap lever.
27:09That should be impossible, but it has happened before.
27:14I once asked for flaps, and the pilot monitoring selected the gear down.
27:20And those levers are far apart.
27:25Still, it's hard to imagine looking at these levers, that you'd get them confused.
27:31True.
27:38Maybe he wasn't looking at them.
27:43Why would an experienced captain not check which levers he was moving?
27:53Okay, visual, visual.
27:55Okay, visual.
27:58Investigators returned to the voice recording of Yeti Airlines Flight 691
28:02to determine if the captain's attention was elsewhere when he selected the wrong levers.
28:07Okay, make sure you stay between the mountains and the runway.
28:11They revisit the moment just before the propellers were feathered.
28:15Keep your power nose up.
28:17Keep visual with the tower.
28:19Don't go too far.
28:21Okay, copy that.
28:24Okay, stop for a second.
28:28He's giving her a lot of instructions.
28:32Maybe that's the distraction.
28:35But she's a very experienced pilot, so why is he doing that?
28:41When you're giving instruction, that's an added mental stress.
28:45It's an added cognitive load.
28:47It's very distracting.
28:49Let's start from the top.
28:52Poker Tower, Yeti Airlines 691.
28:56Yeti Airlines 691.
29:00Tower, Yeti 691.
29:02Descending through 12,500 feet.
29:06Roger, Yeti 691.
29:0812,500 feet.
29:10Expect to land on runway 30.
29:13Runway 30, Yeti 691.
29:18They discover that Flight 691 was initially cleared to land on a different runway, runway 30.
29:26But eight minutes later, there's a change of plan.
29:29If traffic permits, let's land on runway 12.
29:33Then you'll be approved for runway 12 without any instructor pilot supervision.
29:38Okay, runway 12.
29:41Not only is he monitoring the flight, he's approving her to land at Poker's new airport.
29:49Investigators discover Captain Casey was instructing pilots on how to land on both runways at the new airport.
29:57I flew with Captain Kamal Casey just two days before for my route qualification into Poker International Airport.
30:06But why runway 12?
30:11You'll be approved to land in both directions.
30:14Copy that.
30:20Okay, stop it.
30:22So Captain Katiwada is cleared for runway 30.
30:27And Captain Casey decides much later in the game, he's approving her for runway 12.
30:34Captain Katiwada had landed on runway 30, but never 1-2.
30:40Runway 30 is a straight-in approach.
30:47In runway 1-2, you follow a narrow track next to the mountains.
30:51He turned left twice to line up with the runway.
30:55So Captain Casey put Captain Katiwada on a more difficult landing.
31:05Runway 1-2 was a challenging approach for a pilot with just 185 hours on the ATA.
31:12Did Captain Casey properly prepare Captain Katiwada for the difficult approach to runway 1-2?
31:21The best way to prepare a pilot for such an approach would be to do a proper briefing.
31:28Maybe they have photos, videos, simulated training if available.
31:35Investigators examine Captain Katiwada's training records.
31:41She spent no time in the simulator training on runway 1-2.
31:45What about a formal briefing?
31:47There's no documentation related to training on 1-2.
31:51I've got Captain Casey's flight history.
31:55Was Captain Casey even qualified to train others for landing on runway 1-2?
32:01Turns out he had only landed on 1-2 twice.
32:06A bit of experience, but not enough.
32:12Because of his low experience and also Katiwada's low experience on the aircraft.
32:18I find that a bit strange.
32:22I wonder if it's even possible to do a stabilized visual landing using that approach.
32:36A stabilized visual approach is one that's conducted with the runway in sight, at a normal rate of descent, with
32:44landing flaps and landing gear down.
32:46At the proper airspeed, and with all checklists completed, by a certain point.
32:53There's just over one mile between the completion of the last turn and the runway.
33:00That's going to give you just over 30 seconds from lining up to landing. It's very tight.
33:11A visual landing can increase the workload because they have to make tiny adjustments all the way through the pattern.
33:19Let's see how they handle the workload.
33:23Okay, make sure you stay between the mountains and the runway.
33:27To understand how the pilots dealt with the final approach to runway 1-2, investigators return to the CVR.
33:35Keep your power nose up.
33:37Keep visual with the tower.
33:40Don't go too far.
33:41Okay, copy that.
33:43Remember, you need to make an early turn here.
33:47Okay, a beam tower.
33:50Gear down.
33:51Gear down.
33:57Can I fly it manually?
33:59Wait.
34:00Wait, not yet. Keep going straight.
34:03After flaps 30, then you're good to go manual.
34:07Hold on.
34:09Captain Casey is so focused on pointing out landmarks outside the cockpit, he's not paying attention to what's happening inside
34:15the cockpit.
34:19It's normal to let the less experienced pilot fly the aircraft and the most experienced pilot do the analysis.
34:27Okay, flaps 30?
34:30Flaps 30.
34:35Continue to sense.
34:37Okay.
34:42You probably didn't even look down to see what lever he was moving.
34:47But there is still an opportunity to catch the mistake when they do the landing checklist.
34:55The before landing checklist was an opportunity for him to look down at that control pedestal and see that he
35:03had moved the condition levers into Feather.
35:05I'm almost certain they could have recovered right up until the last few seconds.
35:11Did the pilots' failure to follow their checklist ultimately determine their fate?
35:22Nepali investigators continue listening to the CVR of Flight 691 to learn whether the pilots followed the proper procedures before
35:31landing.
35:32Before landing checklist.
35:37Okay.
35:39Landing gear.
35:40Down three green.
35:42Flaps?
35:4330.
35:44Wait.
35:45Captain Kariwata said the flaps are at 30, but according to the FDR they're still set at 15.
35:53Neither pilot checked the flap settings.
35:57If Captain KC saw that the flaps were not at 30, he may have realized he had moved the wrong
36:03lever.
36:05Power management?
36:06Takeoff.
36:07TLU?
36:08Low speed.
36:09Icing. AOA.
36:11Check.
36:12External lights on?
36:13On.
36:14Complete.
36:17They rushed it.
36:20The before landing checklist was done very fast.
36:23Like bam, bam, bam, bam, bam.
36:25And I doubt any of them looked at the flap setting.
36:28They just answered by memory.
36:31Oh.
36:32And with the props feathered, there should have been warning lights.
36:37Why didn't they figure it out?
36:48When the propellers are feathered, they're no longer providing power to the generators.
36:54An aural and visual ELEC warning alerts the pilots that they're losing electrical power.
37:01What is this?
37:03ELEC is on CAP.
37:07The ELEC light comes on to warn the pilots, hey, you've got a big electrical problem.
37:13Checked.
37:14Checked.
37:15Someone clicked off the warning.
37:17They clicked off the warning without figuring out why it even came on.
37:24It's hard to tell why Captain Kamal KC responded, checked, to the electrical light.
37:30Checked.
37:31Would you pull out a quick reference handbook and start working a long electrical failure procedure?
37:36Or would you recognize, hey, I'm landing in less than 60 seconds.
37:40Let's just bring the plane in and deal with the problem on the ground.
37:44We just continue, right?
37:46Yes. Continue turn.
37:52What's that click about?
37:59FDR data shows this is where the flaps goes to 30.
38:03So he notices the flap is not set at 30 and corrects it.
38:13And with so much workload, all he sees is the flap weaver and doesn't notice that the propellers are feathered.
38:21When your workload increases, you get tunnel vision and you see less.
38:26That makes it very difficult because now you only focus on one thing.
38:32Okay, but why doesn't he figure it out when the engines have dropped to idle?
38:42Seconds from the runway, Captain KC realizes there's an issue with the engines.
38:47There's no power.
38:49There's no power.
38:51Add power.
38:55Even though the pilots see the engines are at idle, they are still unaware that the propellers are feathered.
39:01There's no power. No power.
39:03Add power.
39:06There's no torque.
39:08Okay, give it to me.
39:10In desperation, Captain KC takes control of the plane.
39:15You're landing, sir.
39:16No power. Torque indication zero.
39:20200.
39:228691.
39:25What's happening?
39:39He decided to fly the plane rather than try to diagnose the problem.
39:52One single glance around the cockpit could have told him that he had feathered the propellers.
40:05The final report of the Nepali Accident Investigation Commission concludes that the most probable cause of the accident
40:12was the inadvertent movement of both condition levers to the feathered position in flight.
40:20What strikes me about this is that it was a very normal situation.
40:24The only thing that went between success and failure was the slip of a hand.
40:34The proximity to terrain and sharp turn required to land on runway 12.
40:40Before landing checklist.
40:42Combined with a high workload and a lack of appropriate training all contributed to the crash.
40:51After the accident, Yeti Airlines tests the approach in the simulator with their pilots.
40:57Most of our pilots were not able to land on runway 12.
41:02Either they were high on approach or they were fast on speed.
41:09Yeti Airlines stops flying into runway 12 until they are able to establish a safe visual procedure and retrain their
41:18pilots.
41:19The Commission recommends that the Civil Aviation Authority of Nepal ensures that a stabilised flight path is approved
41:27before allowing commercial operations at a new airport.
41:33After the accident, the victims of Yeti Air Flight 691 are mourned by a nation.
41:40And fellow pilots remember their colleagues.
41:45For Captain Kamal Casey, I just want to remember him when he was alive and he was there with us.
41:57Captain Khatiboda, I respected her a lot.
42:02Captain Khatiboda, she will be remembered as an elder sister.
42:05And there is going to be always a void in the airlines that she is not there anymore.
42:14Captain Khatiboda is yet another Costa.
42:14And there is no longer the envelope in the air.ika
42:14player in the air without any more.