- vor 2 Tagen
On 12 April 1990, Widerøe Flight 839 crashes into the water shortly after takeoff from Værøy Airport in Norway, killing all five people on board. The investigation determined that the aircraft suffered a structural failure due to strong winds that exceeded its design criteria.
Kategorie
📚
LernenTranskript
00:02Just moments after taking off from a remote island in Norway...
00:09Something's wrong.
00:10...the pilots of Videro Flight 839 lose control of their plane.
00:14Oh, God!
00:15...it plunges into the Norwegian sea, killing everyone on board.
00:22In the wreckage, investigators find damage to a critical part.
00:27The upper end is broken.
00:30It didn't make a great deal of sense.
00:34And when they learn another Videro Flight nearly met the same fate at the same airport...
00:39Looks like they lost control of the plane for two minutes.
00:43We're going over!
00:48...they discover a controversial decision that put lives at risk.
00:53I wish that we had put our foot down and said no more.
00:57We'll be there.
01:05We'll be there.
01:07Thank you for my time.
01:08I'll wait to see you.
01:09That's your own process.
01:26What did you see about sign on?
01:30Vidaro flight 836 is heading to a remote outpost on the Lofoten
01:35archipelago in the Norwegian Sea.
01:38Lofoten is one of the most beautiful places in Norway.
01:44It's a place where a Norwegian would want to go on holiday
01:47to experience untouched nature
01:49and especially the beautiful mountains.
01:55Tonight's flight is carrying 11 passengers.
01:58Most are Norwegians traveling to the islands from the mainland.
02:05Vidaro 836, runway 25 free, winds variable 1021 at 260 degrees.
02:13Visibility 2,500 meters.
02:15Copy that.
02:16Vidaro 836.
02:22Vidaro is Norway's largest regional airline.
02:26It serves remote communities across the country.
02:30Vidaro 936.
02:31Since the 1960s and 70s, it was a push in Norway
02:34to build regional airports in rural areas.
02:38It's made people feel less isolated
02:41and it made traveling a lot easier.
02:46The plane is heading first to the small island of Vare
02:49and then southwest to Rust
02:52before returning to the mainland city of Boda.
02:57approach checklist 12 miles from the airport the crew prepares for landing
03:05the crew was experienced but this was the first time the captain had flown into that
03:17they're flying a de Havilland twin otter it's a twin turboprop utility aircraft a workhorse for
03:26getting in and out of small remote airports the best airplane in the world it's an incredibly
03:35sturdy aircraft very pilot-friendly we have a long mountainous coast and for that between
03:44otter was perfect landing lights on vidro flight 836 is now minutes from landing at varay and seat
03:59belt already on but the airport is notorious for unpredictable winds very translated means the
04:09weather island the airport was located to the north of the island between the mountain and the sea it's
04:18a very demanding flying environment because the weather changes all the time so the pilots have
04:24set up to that set flaps I'm upset with the runway in sight the pilots begin to line up for
04:36landing
04:37but just as the plane turns it's rocked by turbulence
04:48I have control you have control when flying at varay you will experience turbulence and you will be tossed
05:00around this isn't getting better go around
05:11he obviously decided that the situation was not good to land so he went around and it was a great
05:16call
05:16on his part
05:19laps up
05:20as the captain powers out of the landing the plane is hit with a powerful downdraft and extreme turbulence
05:32you get sort of a tunnel vision when you get sort of a tunnel vision when you're in a situation
05:36like
05:36that and you pull out all your resources and you try to counteract the situation that you're in
05:45for two minutes the captain struggles to level the plane
05:52he was in extreme turbulence you're momentarily out of control you may or may not regain control
06:07we're going over the force of the wind becomes so great that the plane rolls over speeding towards
06:15the mountains
06:18altitude
06:21I can't see anything
06:34come on
06:43only 250 feet from the ground the captain levels the plane and pulls out of the dive
06:56I just can't believe that he recovered at such a low altitude
07:04put in headings for rust
07:11Vitero 836 has aborted landing redirecting to rust
07:15copy that Vitero 836 stay safe
07:19everyone okay back there
07:28Vitero flight 836 escapes disaster no one on board is injured
07:37I'm still shaking my head at that one that was an ace pilot
07:44in the city of Boda officials from Vitero Airlines cancel all flights into Vare while they try and
07:51piece together what happened with flight 836 as part of an internal investigation
07:57the pilot is interviewed we were lining up for approach turbulence was getting worse and worse
08:06I have control
08:11it was obvious we couldn't land I applied power to the engines and we climbed to about
08:151800 feet where we got hit with a massive downdraft
08:26we're going over
08:34I battled that plane trying to keep it away from the mountains
08:48eventually I was able to level out climb to a safe altitude and turn for roost
08:56it would be terrifying for them I'm sure
09:01I've heard stories about that airport
09:06and they're true
09:10the pilots were not very happy
09:13we realized this had been a serious incident
09:17and we had to tighten the operational requirement at the island to make that a safer
09:26the first action taken by Vitero officials is to reduce the maximum wind speeds for takeoff and landing at Vare
09:34airport from 20 to 15 knots
09:37Vitero asks the civil aviation authority to install anemometers devices that monitor and transmit wind speeds
09:45two are installed at each end of the airstrip and one is installed on the mountain
09:50the mountain is its own weather maker it can cause winds to change in direction change in speed which are
09:57conducive to making some serious turbulence
10:02it's called terrain induced turbulence when winds hit the mountains on Vare they tend to accelerate over the top and
10:10drop down towards the airstrip
10:12this creates powerful down drafts and crosswinds the sudden changes in wind speeds and direction
10:19can create wind shear and cause a pilot to lose control
10:24this was a difficult place to operate when the wind was flying over the mountains and down onto the airport
10:31and we had to tighten those restrictions quite severely and quickly
10:39but will the restrictions at Vare be enough to ensure the safety of future flights
10:50it's been 15 months since Vitero flight 836 had their close call at Vare airport
10:57Vitero flight 839 has just landed at Vare and is refueling before heading back to the mainland for Easter weekend
11:06anti-collision light
11:09on
11:10aft and forward boost
11:12on
11:13Captain Ida Nils Pearsson is the pilot in command
11:19Ida was a very level-headed fellow
11:22he was a top-rated pilot
11:25and he'd been with us for years
11:28start switch
11:29left engine
11:32the first officer is Ant Vidar Grunerfloter
11:36on
11:37right engine
11:38right engine
11:41on
11:42the first officer was fairly new
11:46I think he'd been with us for only about a year
11:52look at that windsock
11:54it's flapping like mad
11:56welcome to Vare
11:59buckle up folks
12:00it's gonna be a bit bumpy getting out of here
12:03there are three passengers on board
12:06including a young couple
12:08all right Vitero 839 ready to taxi
12:10Vitero 839 roger
12:12no known traffic
12:14runway free
12:15wind variable
12:16middle direction
12:17250
12:18at 21
12:19max 57
12:21QNH
12:21Niner 88
12:23copy Niner 88
12:26the captain he was a local pilot
12:29he knew the weather
12:30he knew the limitations of the aircraft
12:33knew the limitations of the airport
12:37as they line up at the end of the runway
12:39the crew performs the before takeoff checklist
12:44flap set ten
12:46set ten
12:48heading set to two eight zero
12:50let's make it three two zero
12:54just get clearance
12:55it's calm now we should get going
12:57copy that
12:59tower Vitero 839 requesting clearance
13:02Vitero 839
13:03Vodot control clears Vitero 839 direct Vodot at 5,000 feet and squawk 0-1-3-5
13:09copy
13:11Vitero 839
13:12here we go
13:20wind has varied
13:212-1-0-2-2-9-0 degrees
13:25the gusts of 34
13:27yep
13:28roger we are rolling
13:3170 knots
13:3380 knots
13:39rotate
13:41at 2-43
13:43Vitero flight 839 takes off from Vare and heads for the mainland
13:50the return flight to Vodot will take less than 30 minutes
13:57flaps up
14:01ten seconds after takeoff
14:04a strange noise catches the pilots attention
14:09you don't want anything unusual to happen in that phase of the flight
14:13since you are very close to the ground
14:18they struggle to keep the plane level
14:22steady
14:28something's wrong
14:38and then
14:39the nose of the plane drops and the captain can't do anything to raise it
14:43no
14:45no
14:46no no no
14:53oh god
14:56just 63 seconds after lifting off
15:01Vitero flight 839
15:05slams into the sea
15:12Viro 839, this is Vare Tower. Do you copy?
15:17Viro 839, Vare information on 119.4
15:28Within hours, search and rescue teams spot debris on the ocean's surface 6.5 kilometers northwest of the airport.
15:38The wreckage was found three days after the accident. Harsh sea conditions made it challenged.
15:50The bodies of the three passengers and the first officer are recovered. Captain Pearson's remains are never found.
15:59The accident caused a lot of grief. Vare is a small island where everyone know each other, so everyone felt
16:07they had lost someone close to them.
16:11Investigators from the Norwegian Accident Commission for Civil Aviation, or HSL, soon arrive on the island.
16:19The purpose of the Vidra investigation was to find out what happened during that incident.
16:30I was manager air safety for Boeing Canada to have on a division, and I traveled to Vare to assist
16:37with the investigation.
16:39The airfield was spectacular, but I was somewhat surprised in the closeness of the mountain range, which paralleled the entire
16:48runway.
16:53Investigators start by interviewing the controller, who briefs pilots on the local weather.
16:57Sorry about that.
16:58That's fine. Can you walk me through what happened the day of the accident?
17:02Normal day, by our standards.
17:04They landed at 14.30, refueled, changed passengers, and asked to taxi out. The whole turnaround was less than 15
17:12minutes.
17:12What were the winds when they took off?
17:15It was gusting when they were parked, but eased off to 34 on the west end. The winds were coming
17:20from every direction. It's pretty common.
17:23Did the pilots have any hesitation about taking off?
17:26No, not at all.
17:28And what about the takeoff?
17:30The controller explains that after the plane passed the tower, it turned and then disappeared into the clouds.
17:40What was the cloud ceiling at the time?
17:431,000 feet. I received a distress signal, and a few seconds later, I heard a bang.
17:51That was fast.
17:52They were airborne for just over a minute.
17:55Did they call mayday or relay any information about mechanical issues?
18:01Nothing.
18:03That was helpful. Thank you.
18:07Could there have been a structural failure or loss of power which caused Flight 839 to crash so quickly into
18:15the sea?
18:21Investigators survey the wreckage of Videro Flight 839 for any signs that would explain a crash so soon after takeoff.
18:28Nose and cockpit completely crushed.
18:33Both wings, engines, undercarriage, and tail section severed from the fuselage on impact and carried forward.
18:45High energy impact.
18:49With the nose buckled the way it was, and the left wingtip buckled, we had a pretty good idea of
18:57how the aircraft impacted the sea.
19:03The wreckage tells investigators the plane entered the water nose first at high speed.
19:13The team considers whether engine failure caused the high speed impact.
19:18The manufacturer provides their report.
19:21No fire damage.
19:23Both engines appeared to be running at high RPM and torque at the time of impact.
19:29The engine manufacturer determined that the engines were running, and they were ruled out very, very quickly.
19:37With engine failure ruled out, they wonder whether any parts that control the plane's pitch or steering failed, causing it
19:45to plunge into the sea.
19:49The right elevator sheared in half, maybe due to impact.
19:55The elevator is a control surface on the twin otter's tail that adjusts pitch.
20:05Investigators discover something unusual in the elevator connecting rod.
20:13The elevator connecting rod moves the elevators up and down on the tail.
20:19It's activated when the pilot pushes or pulls on the control column.
20:25The upper end is broken.
20:27What would cause such a vital part to break?
20:31You shouldn't have any preconceived notions as to why the part failed.
20:37Let's get this elevator rod to metallurgy.
20:40I want to know how it failed.
20:44Did the part fail because there was a manufacturing defect?
20:48Did it fail because there was a tool mark on it?
20:53You should let the part tell you the story.
20:57While investigators wait for the metallurgical results, they research the plane's history, looking for any clues into what might have
21:05caused the elevator connecting rod to fail.
21:08So the twin otter DHC-6300 was purchased by Vitro in 1977.
21:15The last daily inspection was carried out the day of the accident.
21:18Maintenance all in accordance with current regulations.
21:20So not a maintenance issue.
21:27The investigators went through all the maintenance documentation.
21:32All the inspections was completed and no deviations was found.
21:38With maintenance ruled out as a cause for the failure of the elevator connecting rod, investigators review the results of
21:46a metallurgical examination performed on the rod.
21:49There's no pre-existing cracks.
21:52There's banding here and here.
21:56Banding is created because you have a repeated load that is applied on and off to your part.
22:02And every time the load is applied, you have a crack that grows a little bit more and it creates
22:09a rainbow on the fracture surface.
22:12The report also reveals the banding occurred because of sideways bending on the rod.
22:20This was highly unusual.
22:22There's never any side loads on that rod.
22:25It just moves up and down.
22:28So it didn't make a great deal of sense.
22:32Investigators examined schematics of the tail section of the twin otter to determine what would bend the elevator connecting rods
22:40sideways, causing it to break.
22:42So what if this elevator broke in flight?
22:47It was being freely and uncontrollably.
22:52It would definitely cause the rod to bend.
22:59If the right elevator separated from its mounts in flight, it would swing in every direction, putting sideways pressure on
23:07the rod and ultimately causing it to break.
23:12First the elevator, then the rod.
23:17It's the only thing that makes sense.
23:20It's kind of like the cart before the horse.
23:23The control rod would not have seen any loads had the elevator not broken.
23:30What would cause the elevator to break in flight?
23:33Maybe the cockpit voice recorder can shed some light on that.
23:43Okay, let's start with the take-off roll.
23:47Norwegian investigators listened to the cockpit voice recorder for clues as to how the right elevator on Videro flight 839
23:55might have come loose, bending the connecting rod.
23:5970 knots.
24:0180 knots.
24:03Rotate.
24:05It was amazing that the cockpit voice recorder was in the aircraft in the first place because it was not
24:11mandatory at the time.
24:16Claps up.
24:23Did you hear that clattering noise?
24:28Strange.
24:34Steady.
24:41Something's wrong.
24:45Stop.
24:47There it is again.
24:49Is that the elevator?
24:52Play it back again.
24:55When I listened to the CVR, there was nothing that I could pinpoint as being the source of the clattering
25:04sound.
25:10Could it have been the elevator breaking?
25:12It was possible, but we really just don't know.
25:16Did you hear the propellers?
25:1755 seconds into the flight, investigators hear the sound of propellers rotating out of sync.
25:26This occurs when there's a change in the aircraft's pitch.
25:33A sudden gust of wind or change in wind direction would cause the propellers to adjust to compensate for the
25:42changing attitude of the aircraft.
25:46Investigators discover that Videro 839 was struck by severe turbulence shortly after takeoff.
25:53The crash happens just ten seconds later.
26:01No.
26:02No, no, no, no.
26:04Oh, God!
26:16So, where were they exactly when they were struck by severe turbulence?
26:19A standard operating procedure calls for a rate of ascend of 1,000 to 1,200 feet per minute.
26:25So, they would have hit turbulence right after they entered clouds at about 1,000 feet.
26:34And that mountain ridge there is just over 1,000 feet.
26:38Now, it looks like terrain-induced turbulence.
26:45The quicker you could get away from the mountains, the better it was.
26:52How bad could those winds have been?
26:56How bad could those winds have been?
26:57Investigators learn of the near crash of the other Videro plane, Flight 836, on Approach DeVare 15 months earlier.
27:06Looks like they lost control of the plane for two minutes, even when inverted.
27:16At what altitude did they lose control?
27:19About 1,800 feet.
27:21About 1,800 feet.
27:22Just after he had boarded the landing on runway 25 due to winds.
27:29Both flights encountered dangerous winds at or above the mountain ridges.
27:35Were any measures put into place to prevent this from happening again?
27:38After Flight 836's missed approach, Flight Order 17 was put into place.
27:45So, they made this change.
27:47Landings and departures must not be planned or executed with variable winds above 15 knots.
27:52So, they reduced the maximum allowable wind speeds for takeoff and landing.
27:59Videro established some very significant wind restrictions using some very experienced crew to develop them.
28:08But there was still unpredictability.
28:13Anemometers were also installed at both ends of the runway and on the mountain ridge.
28:23It's good to have an anemometer on top of a mountain.
28:26It just gives the pilot more information for the landing.
28:30So, what were the mountain winds at the time of Flight 839?
28:37Huh.
28:39There is no anemometer data for the mountain.
28:46If it doesn't provide data, it's absolutely no use.
28:52Investigators contact the Civil Aviation Authority to determine why there weren't any mountain anemometer wind readings at the time of
28:59the crash of Videro Flight 839.
29:06The anemometer was taken down.
29:11They learned that the anemometer on the mountain wasn't reliable because of the icy conditions.
29:17A year after being installed, it was removed from the mountain for repair.
29:23It gets worse.
29:25It was never reinstalled.
29:28It was officially taken out of service three days before the accident.
29:36The removal of the anemometer is a decoration safety.
29:41It's information that a pilot would certainly require for an airport like that.
29:46Okay.
29:48So, what wind information were the pilots actually getting, and when?
29:56Investigators listened to the CVR recording of Videro Flight 839 before it landed at Vare.
30:02I'm going to bank west of the island to avoid more turbulence.
30:06I'm getting updrafts already.
30:08Copy that.
30:09Videro 839, runway free, wind east side, 270 degrees at max 23.
30:17Understood.
30:18Videro 839.
30:2223 knots.
30:23That's 8 knots above the limit.
30:26They shouldn't even have landed the inbound flight in the first place.
30:30What about when they're on the ground?
30:40Look at that windsock.
30:43It's flapping like mad.
30:46Welcome to Vare.
30:49The pilot was talking a lot about the wind, and they were discussing that the wind was coming from all
30:57directions.
30:58Videro 839, roger.
31:00No known traffic, runway free, wind variable, middle direction, 250.
31:06At 21, max 57.
31:08What did you say again?
31:10Max 57?
31:11Yeah.
31:12Max 57.
31:17Coffee.
31:2257 knots.
31:2557 knots is more than 65 miles per hour.
31:31Yeah.
31:31The manual says that the twin otter must not be operated on the ground in winds above 50 knots.
31:39Well, he is sticking his neck out on the line, and I'm not quite sure why he did that.
31:45Were the winds that strong when they took off?
31:51They go through their pre-takeoff checklist, and then...
31:56Just get clearance.
31:58It's calm now.
31:58We should get going.
32:00Copy that.
32:01The captain says it's calm.
32:03What's he basing that on?
32:04Wind socks?
32:05The rains had stopped.
32:06Maybe it looked like the weather was clearing.
32:11If a shower was approaching, you could expect variable winds.
32:15But when the shower passed, you could expect a lull in the wind.
32:25According to the transcript, they get their next wind report as they're about to take off.
32:31Wind has varied 210 to 290 degrees with gusts of 34.
32:38Yeah, Roger.
32:39We are rolling.
32:43They took off in a 34-knot wind.
32:46That's more than double the limit.
32:49If the winds were gusting at 57 knots on the ground, then who knows how strong the winds were coming
32:54off the mountain.
32:56Strong enough to break the elevator.
33:16The team concludes the winds were strong enough to break the right elevator from its mounts, causing the connecting rod
33:25to break, making both elevators unusual.
33:31They ignored Vitero's wind limits on the ground, and they had no wind limits in the dangerous area around the
33:39mountain.
33:40Why were they so eager to leave?
33:44This was Easter weekend, and there is an incentive to get home.
33:53There was clearly some concern, but they went.
34:05To understand why the captain of Flight 839 took off in winds that exceeded company limits, investigators interview other Vitero
34:14pilots about wind restrictions at Vare.
34:17What has been your experience at Vare?
34:21I don't like it.
34:22None of the pilots do.
34:24The wind reports aren't reliable.
34:29You could actually sit on the tarmac, get one wind indication, move towards the runway, and get another.
34:37Even though the maximum wind speeds were reduced from 20 knots to 15?
34:41Well, they were, but they brought it back up to 20.
34:47Nine months after the incident with the first Vitero flight, the wind restrictions were reversed.
34:56Why would they do that?
34:58My guess?
34:59Too many cancellations.
35:05After Vitero lowered the wind limits, cancellations increased.
35:10That led to negative press and anger from local residents.
35:14The decision to cancel flights became very unpopular.
35:21It was so unpredictable at Vare.
35:26Did pilots feel pressure to complete the flights?
35:31Yeah, but not from the airline.
35:35I had a situation where the weather turned into a hurricane and it could not take off.
35:40And I got a real work over from some of the passengers.
35:45Investigators researched the impact those wind-related cancellations had on Vitero's operations.
35:54The pressure was piling on from the public.
35:57Cancellations tripled in the last 12 months.
36:02Compared to other airports in Europe, Vare had a lot of cancellations, and the flights were often cancelled quite early
36:09when the wind was strong.
36:11But when the flights were supposed to arrive, it could be no wind at all, which made people question all
36:18the cancellations.
36:20Almost all the cancellations were being caused by winds.
36:23Because of that, bad press, which gets the attention of the government.
36:30The government paid the company to fly there.
36:34The company wrote the government and said it was extremely difficult to operate there.
36:40And the reply from the government was, if you don't fly there, we will have to take the money away.
36:46Out of curiosity, how many cancellations were there on departure from Vare?
36:58None.
37:01Basically, it's get home, Midas.
37:03If they're at the airport, pilots are going to tell themselves they're capable of taking off as well.
37:09You know, there's still one thing I don't get.
37:14The conditions were so treacherous.
37:17Why was this airport even built there in the first place?
37:27So, why was this location chosen for the airport?
37:32Investigators consult officials about the viability of Vare Airport to determine if passengers and crew were placed at risk unnecessarily.
37:44Vidre had two possible locations for the airport at the island.
37:48This one was chosen despite the difficulties with wind conditions near a mountain ridge.
37:59Okay, and what testing went into the decision?
38:03Vidre had done test flights at Vare prior to the decision of building the airport there.
38:09And they had experienced very windy conditions and did not recommend building the airport there.
38:19So, if Vidre was against it, then why did it go ahead?
38:23We knew that the wind conditions at Vare would be so difficult, it would affect regularity.
38:31But that advice was ignored by the meteorology specialists that the authorities had consulted when it came to put the
38:42airport on the island.
38:44Maybe some of the decisions that were made were more politically motivated than were practical.
38:55Investigators now know the factors that led to the deaths of three passengers and two pilots on board Vidreau Flight
39:02839.
39:03First up, you have an airport next to a mountain, resulting in dangerous winds.
39:09Lower wind limits are imposed, but the result is an increase in cancellations.
39:14Which forces the limits to change again.
39:18Limits go back up, and then finally, the unreliable wind data, which results in wind reports being ignored by pilots.
39:32Rules are established for a reason.
39:35If you don't follow the rules, you're taking a big risk.
39:41Wind has varied 210 to 290 degrees, the gusts of 34.
39:47Yep, Roger, we are rolling.
39:55Vidreau Flight 839 enters turbulent airspace when the winds coming off the mountain were extreme.
40:03The force of the winds causes the right elevator to break free.
40:10Something's wrong.
40:13Bending the connecting rod until it fails.
40:20No.
40:22No, no, no.
40:26It was subject to aerodynamic loads that exceeded the structural strength of the tail.
40:37It must have been absolutely terrifying.
40:40Because you would pull the control column without any reaction at all.
40:45Oh, God!
40:57The Norwegian Accident Commission for Civil Aviation recommends new regulations for the distribution of wind information to crews.
41:06And urges Vidreau to ensure their pilots follow established restrictions.
41:11The captain wanted to get the job done.
41:14And he probably got away with it other times.
41:17But this time, it didn't work out.
41:24Other recommendations are made for Vare Airport.
41:28But ultimately, it is deemed too dangerous, and the airport never reopens to commercial traffic.
41:36Vare Airport was open only four years, which makes it one of the shortest-lived airports in the world.
41:47I wish that we had put our foot down and said no more.
41:54I wish the company had done the same.
42:00I wish the government and the experts had listened to our warnings earlier.
42:08Then we might have had our colleagues still alive.
42:12Then we might have had our colleagues still alive.