- vor 23 Stunden
On 27 February 2001, both engines on Loganair Flight 670A flame out shortly after takeoff from Edinburgh Airport. The aircraft later ditches in the Firth of Forth, killing both of the pilots. It was later determined that large amounts of snow had entered the engine air intakes.
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LernenTranskript
00:00What did you do?
00:09Nothing.
00:10Did you hear those noises?
00:12I did.
00:13The audio playback of the cockpit voice recorder
00:15gave the investigators the first real clue
00:18as to the cause of the accident.
00:21Logan Air 670A loses two engines
00:24and crashes into the North Sea.
00:27Both pilots are dead.
00:29Why would that trigger a dual-engine failure?
00:32It's never happened in the past.
00:34Serious aircraft accidents
00:35rarely have one causal factor.
00:39It's a combination of circumstances.
00:41Here's something.
00:42The crew called an engineer before departing.
00:45Well done.
00:45Why did the crew need to investigate a problem?
00:48Brace, brace, brace!
00:54Me, me, me, me!
00:55It's mid-afternoon on a chilly winter day
01:18at Edinburgh Airport in Scotland.
01:20Several aircraft are preparing for departure,
01:24including Logan Air Flight 670A.
01:29At the time, Logan Air, a Scottish carrier,
01:32was a franchisee of British Airways.
01:34It operates about 40 different aircraft
01:37and it does that in a variety of modes,
01:40whether it's passenger or cargo,
01:42to support a dispersed population.
01:45Anti-collision beacon.
01:47Anti-collision beacon on.
01:50Running through pre-departure checks
01:52is 58-year-old Captain Carl Mason
01:55and 29-year-old First Officer Russell Dixon.
02:00Start, master, and...
02:03Engine start sequence.
02:05Starting right engine.
02:07The captain is hugely experienced.
02:10He had Royal Air Force training
02:13before he became a civilian pilot.
02:15One, two, three...
02:18First Officer Dixon passed his training
02:21with no failures or scrapes.
02:24Ignition.
02:25Fuel lever forward.
02:28We have ignition.
02:29500, 600, 700.
02:33The pilots are at the controls
02:36of a Shorts 360,
02:37known as the Shed,
02:39and the Flying Shoebox,
02:40for its unusual boxy shape.
02:44The Shorts 360 is a short-haul commuter airplane,
02:47which carries a total of 36 passengers and crew,
02:52or approximately 8,300 kilos of freight.
02:56It's a lovely airplane to fly.
02:59Moments after starting the right engine,
03:03its generator stops.
03:06Let's try that again.
03:08You carry out a set procedure
03:10to try and get the generator back online.
03:13Nine times out of ten,
03:17that will solve the problem.
03:22Starting sequence finished.
03:24Stabilising at 73%.
03:27Ah, not again.
03:32Call maintenance.
03:33The Shed does this from time to time.
03:36The Shorts 360 is powered
03:38by two Pratt & Whitney PT65 engines.
03:41They're a very reliable, robust engine.
03:44However, you could have a fault
03:46with the generator
03:47where it will not be connected
03:48to the aircraft AC electrical systems.
03:51All done.
03:53Perfect. Thank you.
03:54The engineer gives Logan Air 670A
03:57the green light.
04:04Logan Air 670 Alpha,
04:06cleared for TALA 5 Delta,
04:07standard instrument departure.
04:08Logan 670 Alpha,
04:11TALA 5 Delta, roger.
04:15As the pilots taxi towards the runway...
04:19Auto feather test.
04:21They complete final pre-departure checks.
04:25Feathering off.
04:28Today, the plane is carrying
04:30more than 2,000 pounds of letters and boxes.
04:34Destined for Belfast in Northern Ireland
04:36on a scheduled one-hour flight
04:38for Britain's Royal Mail.
04:43Prop levers maximum.
04:45Fuel levers flight.
04:49Logan Air 670A prepares for take-off.
04:5480 knots.
04:56Roger.
04:59V1.
05:01Rotate.
05:02At 5.28 p.m.,
05:06the crew lifts off from Edinburgh Airport.
05:09Cycle landing gear.
05:12It is prudent to cycle the undercarriage
05:15after take-off in these conditions.
05:17The slush can collect in the covers
05:19that the undercarriage retracts into.
05:22As you climb,
05:24this can refreeze as the temperature drops.
05:27Logan Air 670A climbs
05:30as it approaches the North Sea.
05:35Altitude.
05:361,150 feet.
05:39Lots of white caps out there.
05:42It's quite something, isn't it?
05:44The crew would have seen
05:46that the sea was rough.
05:48They knew that the wind
05:50was blowing very, very strongly
05:51because the aircraft
05:52was being buffeted about.
05:56Altitude.
05:582,200 feet.
06:00Not two minutes after take-off,
06:02the crew takes preventative measures.
06:05Let's put the anti-icing on.
06:06So precipitation doesn't form into ice
06:08in the engines and on the wings.
06:10Anti-ice, put on.
06:16What did you do?
06:17Nothing.
06:19The captain realises
06:20they're losing power
06:21in both of the engines.
06:27We have a double engine failure.
06:30Torque is here on both engines.
06:34Dual engine failure.
06:37Fuel?
06:393,000 with plenty.
06:40Without engine power
06:44and only 1,600 feet above the sea,
06:48the crew has little time
06:49to troubleshoot.
06:51If you lose two engines,
06:52you are not going to be able
06:53to maintain altitude,
06:54so it is a very serious situation.
06:57The captain initiates
06:59a right turn towards the coast,
07:01looking for a safe place to land.
07:04Mayday, mayday, mayday.
07:05This is Logan 670 Alpha.
07:07We've got a double engine failure.
07:09Repeat, double engine failure.
07:10Roger.
07:11Logan Air 670 Alpha.
07:12Roger, your mayday.
07:14Turn left, heading 250.
07:16The airfield is three miles
07:17to the northeast.
07:18Airspeed.
07:20115 knots.
07:20We can't relight the engines.
07:24An engine in-flight relight checklist
07:26would take three to four minutes
07:27for an experienced crew at minimum.
07:30These pilots did not have time to do this.
07:331,300 feet.
07:35110 knots.
07:37Without power,
07:38they're rapidly losing altitude.
07:42Altitude?
07:431,200.
07:44With the airport still three miles away
07:48and no suitable place to land on the coast,
07:52Captain Mason has only one risky option.
07:55Prepare to ditch.
07:58If I was going to be on a flight
08:00where everything was going to go wrong,
08:02something like a dual engine failure,
08:04Captain Mason is the guy
08:05I'd like to have in charge.
08:07He has enormous experience
08:10in flying over the very hostile,
08:12freezing cold North Sea.
08:15Best speed is 110 knots.
08:16I'll get us as close to shore as possible.
08:22All they could do
08:24was to make the ditching
08:26as smooth and as slow
08:28as they possibly could
08:30without losing control of the airplane.
08:32They had that task to perform.
08:34If they performed it well,
08:36they hoped they would survive.
08:38Best speed is 100 knots.
08:40Captain Mason prepares the aircraft
08:42as best he can.
08:43The captain increases the pitch
08:46to reduce the speed.
08:48This will hopefully prevent
08:49the nose entering the water first
08:51and hence the aircraft flipping over.
08:55Logan Air 670 Alpha.
08:57We are ditching.
08:58Send recovery.
08:59Send recovery.
09:00Over.
09:02The radio call
09:03doesn't get through.
09:05Logan Air 670 Alpha.
09:06Do you read me?
09:07Logan Air 670 Alpha.
09:09Over.
09:13Pull up.
09:15Airspeed.
09:16Airspeed.
09:16Airspeed is 88.
09:1887.
09:2086.
09:22Brace.
09:23Brace.
09:24Brace.
09:24Brace.
09:24Brace.
09:24Logan Air 670A
09:35crashes into icy waters
09:37only 65 meters from shore.
09:41Neither pilot is able to escape
09:43from the submerged plane.
09:48It isn't until daybreak
09:50that the tide retreats
09:51and investigators are able
09:53to get a close look
09:54at the wreckage.
09:55The flight deck
09:57was badly crushed.
10:01The bulk of the rearmost fuselage
10:03and the tail units
10:04had broken away.
10:08The aircraft was
10:09in a nose-down attitude
10:11with the engines
10:12really stuck into the sand.
10:16What could have caused
10:18both engines to fail
10:19just minutes after take-off,
10:21resulting in the deaths
10:22of two experienced pilots?
10:30The UK's Air Accidents
10:32Investigation Branch,
10:33or AAIB,
10:35immediately begins
10:36its investigation
10:37into the crash
10:38of Logan Air 670A.
10:41Please send those to HQ.
10:43Salvage teams are able
10:44to recover most of the wreckage.
10:46Start with the engine.
10:47The first message I got
10:51was that the aircraft
10:52had sent out
10:53a distress call
10:54stating that they'd had
10:55a double-engine failure.
10:57Our interest was
10:58very much focused
10:59on the engines.
11:01While the recovered
11:02flight data
11:03and cockpit voice recorders
11:04are prepared for download,
11:08investigators look for damage
11:09to the engines
11:10to explain why
11:11the plane crashed.
11:12Not a single blade
11:18appears bent.
11:20There was no power
11:21on impact.
11:22Neither engine
11:23was working
11:24when the plane
11:25hit the water.
11:26If an aircraft
11:28struck the water
11:29with the engines running,
11:31the result would be
11:32bending of the
11:33compressor blades
11:34in the direction
11:35opposite to that
11:36of the airflow.
11:38We found no evidence
11:40of such bending.
11:40dual-engine failure
11:42is unusual.
11:45Maybe it's
11:46something mechanical,
11:47a problem
11:48or defect
11:48we can't see here.
11:51We'll get the engines
11:52to the manufacturer.
11:54We removed the engines
11:56from the airframe
11:57and shipped them
11:58to the manufacturer
11:59in Montreal
12:00with a view
12:02to finding out
12:03whether there was
12:03any evidence
12:04of mechanical failure
12:05within the engines.
12:06take-off speed
12:13is normal.
12:15With the data
12:16from the flight
12:16recorder downloaded,
12:18the team scrutinizes
12:19the engine parameters
12:20for leads.
12:21The climb is fine.
12:24Two minutes in.
12:26Hmm.
12:27Look at that.
12:28It looks like
12:29both engines
12:30flamed out
12:31at about the same time.
12:32We have a double-engine failure.
12:39Talk is here
12:40on both engines.
12:41A dual-engine failure
12:42is often due
12:43to pilot confusion,
12:44not a mechanical issue.
12:45It's a result
12:46usually of
12:47an engine failing
12:48for some reason
12:49or other,
12:50followed sometime later
12:51by a second engine
12:53shutting down
12:55as a result
12:56of actions
12:57taken
12:58but applied
12:59to the wrong engine.
13:00In 1989,
13:03the pilots
13:03of British Midland Airways
13:05Flight 92
13:05shut down
13:07the wrong engine
13:07after a fan blade broke
13:0913 minutes
13:10after departing
13:11Heathrow Airport
13:12in London.
13:13The plane stalled
13:15and 47 people
13:16were killed.
13:21There's no way
13:22the pilots
13:23accidentally shut down
13:24a second engine
13:25that quickly.
13:26In this instance,
13:28the shutdown
13:29of the two engines
13:31occurred certainly
13:32within seconds
13:32of one another
13:33which really didn't
13:35fit in
13:36with the scenario.
13:42Could you start
13:4380 seconds
13:43into the flight
13:44just before
13:45the engines flame out?
13:47The team now
13:48turns to the cockpit
13:49voice recorder
13:50for insight
13:51into the engine failure.
13:54Altitude?
13:542,200 feet.
13:58Let's put the
13:58anti-icing on.
14:02Anti-ice
14:02both on.
14:07What did you do?
14:10Nothing.
14:13We have a
14:13double engine failure.
14:16Did you hear
14:17those noises?
14:18I did.
14:20I wonder
14:20what they could be.
14:22I'll play it again.
14:23Let's put the
14:29anti-icing on.
14:31Anti-ice
14:32both on.
14:37What did you do?
14:40As soon as the
14:41first officer
14:41turns the
14:42anti-icing
14:42switches on
14:43there's
14:43humming noises
14:44and four
14:45seconds later
14:46both engines
14:47flame out.
14:48The audio
14:51playback
14:52of the
14:52copied
14:52voice
14:53recorder
14:53gave
14:53the
14:54investigators
14:54the
14:55first
14:55real
14:55clue
14:56as to the
14:57cause of the
14:57accident.
15:01What did you do?
15:03Nothing.
15:04It was definitely
15:04linked to the
15:05two switch
15:06selections
15:06followed very
15:07shortly
15:07afterwards
15:08by the
15:08engines running
15:09down.
15:10We have a
15:10double engine
15:11failure.
15:12It took us
15:12here on both
15:13engines.
15:13Why would
15:20activating the
15:21anti-icing
15:21system
15:22somehow
15:22shut down
15:23both engines?
15:25It doesn't make
15:26any sense.
15:26A.A.I.B.
15:36investigators
15:37examined the
15:37anti-icing
15:38system of the
15:39Shorts 360
15:40to determine if
15:41it played a
15:42role in the
15:42dual engine
15:43failure of
15:44Logan Air
15:44Flight 670A.
15:47Maybe the
15:47actuators
15:48failed.
15:48Yes.
15:56Electrical
15:57actuators
15:58operate
15:59mechanical
15:59vanes that
16:00redirect ice
16:01and snow
16:02out of the
16:02back,
16:03preventing ice
16:04from blocking
16:04airflow to
16:05the engine.
16:06When the
16:06vanes are in
16:07operation,
16:08they reduce
16:09air intake
16:09by 50%.
16:11Was the
16:14anti-icing
16:15system working?
16:17Investigators
16:18test another
16:19actuator to
16:20see if it
16:20matches the
16:21humming sound
16:22heard on the
16:23CVR before
16:24both engines
16:25flamed out.
16:26Well, that
16:37sounds familiar.
16:39Tests on
16:40the actuator
16:41produced a
16:42tone which
16:43was similar
16:44to that
16:45detectable on
16:46the cockpit
16:47voice recorder
16:48of the
16:48aircraft.
16:49Shall we
16:50compare it
16:50to the
16:51CVR?
16:51Mm-hmm.
16:53Investigators
16:54listened to
16:54the humming
16:55sound on
16:55the CVR
16:56to confirm
16:57it's the
16:58anti-icing
16:58actuator
16:59operating.
17:06It's the
17:07same.
17:08The matching
17:09sounds indicate
17:11the anti-icing
17:11actuators on
17:12flight 670A
17:14were fully
17:15operational.
17:15as there
17:18was no
17:18other
17:19similar
17:19equipment
17:20in the
17:20aircraft
17:21that
17:21operated
17:22at that
17:22frequency.
17:25The
17:25sounds
17:26must have
17:26been the
17:26result of
17:27operation
17:28of the
17:29anti-ice
17:29system.
17:31Why would
17:32activating the
17:32anti-icing
17:33system trigger
17:34a dual
17:34engine
17:35failure?
17:36It's never
17:37happened in
17:37the past.
17:39Besides,
17:40aircraft use
17:40anti-icing
17:41systems all
17:41the time.
17:44Aircraft
17:44anti-icing
17:45systems remove
17:46ice from
17:47control surfaces,
17:48from the wing,
17:49or from the
17:50engine air
17:50intakes.
17:51That just allows
17:52for the normal
17:53operation of the
17:54aircraft in pretty
17:55poor conditions.
17:59If they were using
18:00the anti-icing
18:00systems, maybe the
18:02weather played a part
18:03in the failure of the
18:03two engines.
18:05Investigators review
18:06the weather chart
18:07for answers.
18:09February 27th,
18:11the crew lifted
18:11off at 5.28pm.
18:14No precipitation,
18:16clouds at 4,500
18:18feet, winds 16
18:20knots, ground
18:21temperature is 2
18:22degrees.
18:24Doesn't sound like
18:24icing conditions
18:25at take-off.
18:26No.
18:27And the plane
18:28wasn't airborne
18:28long enough to
18:29accumulate ice
18:29during the flight.
18:33Hang on.
18:33What about the
18:36storm overnight?
18:39And maybe that
18:40had something to do
18:40with the engine
18:41failure.
18:42It was quite a
18:43storm.
18:45Lots of snow.
18:49A cold wind.
18:53The weather was
18:54appalling.
18:55It was gusting
18:57about 35, 45
18:58miles an hour.
19:00It was snowing
19:01most of the time.
19:03Where was the
19:05plane during the
19:06storm?
19:08The plane landed
19:09in Edinburgh
19:09just after midnight
19:11on February 27th.
19:13The crash happens
19:14later that day.
19:16That's right around
19:17the time the storm
19:18began.
19:19And it took off
19:20at 5.28pm.
19:2317 hours.
19:25Is it possible
19:26the aircraft was
19:27parked outside in
19:28the snow the
19:28entire time?
19:29Let's talk to the
19:33pilot who landed
19:34the plane in
19:34Edinburgh.
19:38Was there
19:39anything specifically
19:40that the previous
19:41crew did,
19:42saw,
19:43noticed,
19:44or understood
19:44which may help
19:45them to actually
19:46understand what
19:47was the causal
19:48elements of this
19:48accident?
19:51How can I help?
19:51what happened
19:54when you arrived
19:55in Edinburgh?
19:57The AAIB
19:58turns to the
19:59captain of the
20:00inbound flight
20:01for answers.
20:02The weather
20:03wasn't great
20:03when we landed.
20:07It was snowing
20:08and we could see
20:08the weather
20:09was going to
20:09get worse.
20:11We taxied in
20:12and parked
20:12the plane
20:12at stand 31
20:13with the
20:14other aircraft.
20:15Did anything
20:16seem abnormal
20:17with the aircraft?
20:18Nothing unusual
20:19at all.
20:19Once you parked
20:21the plane,
20:22what next?
20:23We supervised
20:24the refuelling.
20:26The plane
20:27was scheduled
20:27for de-icing.
20:34But as you
20:35can imagine,
20:35there was a
20:35backlog.
20:37The plane
20:38was scheduled
20:38to be de-iced
20:39before the
20:40next departure.
20:44Attention all
20:44crews and
20:45passengers.
20:46But then
20:46the airport
20:47was closed.
20:48From midnight,
20:50the snow
20:50started to
20:51become worse.
20:52It was
20:53interrupting
20:53the snow
20:54clearing and
20:54de-icing operations
20:55and by 2 o'clock
20:56the airport
20:58authority elected
20:59to shut the
20:59airport down,
21:00which was the
21:00correct and
21:01sage decision
21:02at that time.
21:08How long
21:08did you stick
21:09around the
21:09airport after
21:10it was closed?
21:11A few hours.
21:14Then at 6am
21:14we learned the
21:15airport wouldn't
21:15be reopening for a
21:16while, so we
21:17secured the
21:18plane and
21:18clocked out.
21:19Secured it how
21:20exactly?
21:21It was shortly
21:22before dawn.
21:24By then it was
21:25really blowing
21:25hard.
21:26It was icy and
21:27there was snow
21:27everywhere.
21:29The captain
21:29explains how the
21:30propellers were
21:31secured.
21:32There are sock
21:33type straps
21:34attached to two
21:35of the propellers.
21:36They are then
21:37attached to the
21:38side of the
21:38fuselage, which
21:39stops the
21:40propellers rotating
21:41in the wind.
21:42after securing
21:45the plane, we
21:46went off duty
21:47and that was
21:48it.
21:50What about the
21:51engine intakes?
21:52Did you cover
21:53them with bungs?
21:55The aircraft
21:56bungs are a
21:57blank which
21:58covers off the
21:59engine intake.
21:59It protects the
22:01engine from the
22:01ingress of dust,
22:03dirt, particles,
22:05insects, snow, and
22:07as such it protects
22:08the engine while the
22:09aircraft is parked.
22:10Normally we
22:11would, but there
22:12were no bungs.
22:18Bungs were
22:19available at the
22:20main bases of
22:21Logan Air, but
22:22not at Edinburgh.
22:24So the flight crew
22:25had no means of
22:27protecting the air
22:28intakes.
22:32Right.
22:33I think that's
22:34everything.
22:35Let me know if
22:36you have any other
22:36questions.
22:37Thanks.
22:38Will do.
22:40The aircraft
22:41should be fitted
22:42with bungs if
22:44the machine was
22:44going to be left
22:45unattended for a
22:46lengthy period.
22:48But Edinburgh
22:49was regarded as
22:50a mere transit
22:51stop.
22:53Therefore, no
22:53bungs were kept
22:54there and the
22:55aircraft didn't
22:56carry any bungs.
22:59We know the
23:00plane parked here
23:01at Stand 31
23:03shortly after
23:04midnight when it
23:04was already
23:05snowing.
23:06The airport
23:07closes two hours
23:08later due to bad
23:08weather.
23:10Investigators
23:11construct a
23:11timeline of the
23:12aircraft during
23:13the snowstorm.
23:16According to the
23:16captain, at 6am,
23:19the crew secures
23:20the plane because
23:20the storm is still
23:21raging.
23:24Secured partially
23:25without bungs,
23:27leaving the engines
23:27exposed.
23:28And then the
23:29crew leaves?
23:29Mm-hmm.
23:32The plane takes
23:33off 11 and a
23:35half hours after
23:35the first crew
23:36secured it.
23:38What time did
23:39the storm end?
23:43The snow
23:44stopped at
23:459.52am.
23:47The cold 30-knot
23:48gusts continued for
23:49a few hours and
23:50the temperature
23:51hovered just
23:52slightly above
23:52freezing by early
23:53afternoon.
23:54That's 10
23:57hours of
23:57exposure to
23:58snow, ice
23:59and wind.
24:04Would that
24:05be enough
24:06time for a
24:07significant amount
24:07of snow to
24:08enter the
24:09engine?
24:11What did you
24:12do?
24:13Nothing.
24:14And somehow
24:15cause both
24:16engines to
24:17fail?
24:17Could
24:23exposure to
24:24a snowstorm
24:25for 10
24:26hours have
24:26contributed to
24:27the dual
24:28engine flame
24:28out on
24:29flight 670A?
24:32Temperature?
24:34Wind?
24:35Investigators
24:36consider the
24:36impact of the
24:37wind conditions.
24:38Hovering around
24:39zero with winds
24:41from the northeast
24:41gusting up to
24:4243 knots.
24:4443 knots?
24:45That's a
24:47strong wind.
24:51Which way was
24:52the plane
24:52parked?
24:54The plane
24:55was parked
24:56straight into
25:00the wind.
25:02The team
25:03discovers the
25:04wind was
25:04blowing snow
25:05and ice
25:06directly into
25:07the plane's
25:07engines for
25:0810 hours.
25:10The aircraft
25:11had been
25:11parked in
25:12extremely nasty
25:13weather conditions.
25:15with driving
25:16snow and
25:17ice pellets.
25:18And the wind
25:19was consistently
25:20down the
25:21centerline of
25:21the aircraft,
25:22which exposed
25:24the intakes
25:24to have
25:25snow and
25:25ice pellets
25:26being blown
25:27into them.
25:3010 hours.
25:32That's a lot
25:32of snow.
25:34True.
25:35But once the
25:36engines are
25:37turned on,
25:37it should melt.
25:39So what's
25:40different here?
25:42Maybe it had
25:42something to do
25:43with the amount
25:43of snow
25:44accumulated?
25:45Could enough
25:46snow have
25:47accumulated in
25:48the engines
25:48to clog the
25:49air intakes
25:50and cause the
25:51crash of
25:52flight 670A?
25:56Mayday,
25:57mayday,
25:57mayday.
25:57This is Logan
25:58670 Alpha.
26:00We've had a
26:00double engine
26:01failure.
26:01Repeat,
26:02double engine
26:02failure.
26:04One of the
26:05things which
26:05makes this
26:06accident a
26:07particular
26:08challenge for
26:08the investigators
26:09is that they're
26:11dealing with
26:12ice and slush
26:13and snow
26:14within the
26:14engine intake.
26:16That disappeared
26:17into the sea
26:17during the
26:18crash.
26:19Brace,
26:19brace,
26:20brace.
26:20Brace,
26:20pull up.
26:29Without knowing
26:30how much snow
26:31collected in the
26:32engines,
26:33investigators keep
26:34the possibility
26:34of an unrelated
26:35engine malfunction
26:36on the table.
26:38Pratt and
26:39Whitney's detailed
26:39examination of the
26:40engines came in.
26:42Did they find
26:42anything?
26:43There are no
26:44faults or defects
26:45with the engines.
26:48As a result of
26:49the examination,
26:50we were satisfied.
26:51There was no
26:51evidence of any
26:52form of mechanical
26:53failure within
26:55the engines.
26:55What about a
27:04compressor surge?
27:05That's an idea.
27:07Could happen if
27:08the airflow is
27:08restricted enough.
27:13When airflow to
27:14the combustion
27:15chambers that
27:16power the
27:16engine's turbines
27:17is severely
27:18interrupted or
27:19restricted,
27:20it can cause a
27:21compressor surge
27:22and can completely
27:24shut down the
27:25engines.
27:25How restricted
27:31would the airflow
27:31have to be for
27:32the engine's
27:33compressor to surge?
27:34I'll check.
27:35Aircraft engines
27:36require pretty much
27:38undisturbed airflow
27:39to work efficiently
27:40and effectively.
27:42Could both
27:43engines have been
27:44starved of enough
27:44oxygen to result in
27:46a dual-engine
27:46flame-out?
27:47Here we go.
27:48For a compressor
27:49to stall and flame-out,
27:50the airflow into the
27:51engine must fall
27:52below 22%.
27:54Mm-hmm.
27:54So that means
27:58snow and ice
28:00would have to block
28:0278%.
28:04That's a significant
28:06percentage.
28:07A 78% reduction in
28:09airflow would explain
28:11why the engines
28:11failed on flight 670A.
28:14Could that much snow
28:16have accumulated
28:16within the engine's
28:17intakes to block
28:1878% of the airflow?
28:20Well, let's find out.
28:24The preliminary
28:25assumption that was
28:26made was that snow
28:29had built up within
28:31the intake system.
28:33We needed some sort
28:35of assurance that
28:36this was a possibility.
28:37I'll handle the snow.
28:46You work the fan.
28:49AAIB investigators
28:50test how snow
28:51might accumulate
28:52and restrict
28:53the engine's
28:54air intake.
28:56So we
28:58produced this
28:59mock-up
29:00of the engine
29:01intake system.
29:04Ready?
29:05And we
29:08utilized
29:09an extractor fan
29:10to create
29:12the airflow
29:12through the engine.
29:13I'll check to see
29:33where it all went.
29:41You're not going to
29:42believe this.
29:43With the plane
29:48facing straight
29:49into the storm,
29:50snow not only
29:51entered the
29:51engine's air
29:52intakes,
29:53but made a
29:5390-degree turn
29:54into the
29:55upper chamber.
29:59These
29:59imitation
30:00snowflakes
30:01all consistently
30:02rose up
30:03to the top
30:03chamber.
30:04And we
30:05satisfied
30:05ourselves
30:06that the
30:06air stream
30:07carrying the
30:08snow
30:09would have
30:10been capable
30:11of depositing
30:11all in the
30:12upper chamber.
30:13The chamber
30:15is full of tubes
30:16and pipes.
30:17The snow
30:18would likely
30:18stick to all
30:19that cold metal.
30:21There are
30:22ducts,
30:22pipes,
30:24cables,
30:25wiring,
30:25and all of
30:26these provide
30:26ample opportunity
30:27for snow
30:28to adhere to,
30:29to gather.
30:31And given that
30:31the aircraft
30:32was exposed to
30:32these conditions
30:33for over 10
30:34hours,
30:35that was how
30:36we believe
30:37that the snow
30:37actually gathered
30:38undetected
30:39within that
30:40area.
30:42But how
30:43would snow
30:44up here
30:44restrict 78%
30:46of airflow
30:46down here?
30:48Good point.
30:49Something else
30:50had to happen
30:51for intakes
30:52to be blocked
30:5278%.
30:53Serious aircraft
31:00accidents
31:00rarely have
31:02one single
31:04causal factor.
31:07There's usually
31:08a primary
31:09causal factor,
31:11but in the end
31:13it's a combination
31:15of circumstances.
31:17What happened
31:18between the end
31:18of the storm
31:19and the plane's
31:21departure?
31:25Here's something.
31:27Did something
31:28else happen
31:28to the snow-filled
31:29engines after
31:30the storm?
31:32The crew called
31:32an engineer
31:33before departing.
31:35One question
31:36for investigators
31:36was why did
31:37the crew
31:38call for the
31:39assistance of
31:39maintenance engineers
31:40to investigate
31:41a problem?
31:44I'll talk
31:44to maintenance.
31:48You helped
31:55the crew
31:56with a concern
31:56before take-off.
31:58Investigators
31:59questioned the
31:59engineer about
32:00the maintenance
32:01call to Logan
32:02Air 670A
32:04the day of the
32:05accident.
32:06They called.
32:06I went over
32:07to have a look.
32:10The AAIB
32:11learns the
32:12captain was
32:13having trouble
32:13starting the
32:14right engine.
32:16Let's try
32:17that again.
32:18The right
32:20engine
32:20generator
32:21would not
32:22come online.
32:26Starting
32:27sequence
32:28finished.
32:29Stabilizing
32:29at 73%.
32:31Not
32:33again.
32:35What this
32:35essentially meant
32:36was that the
32:37aircraft had
32:37half of its
32:38electrical power
32:39only.
32:40And so the
32:40crew quite
32:40correctly shut
32:41down the
32:42engine and
32:42then called
32:43for maintenance
32:43assistance to
32:44determine what
32:45the problem
32:45actually was.
32:46so what did
32:48you do?
32:48I transposed
32:49connections on
32:50the generator
32:50unit and it
32:51restarted.
32:56All done.
32:58Perfect.
32:59Try running the
32:59engines for 30
33:00minutes.
33:01The crew carried
33:02on running the
33:03engines after it
33:04was apparently
33:04fixed.
33:05I left and
33:06that was the
33:07last I heard
33:08from them.
33:10The fact that
33:10the aircraft had
33:11been sitting
33:12around in
33:12in clement
33:13conditions
33:13overnight.
33:14BUP levers
33:15maximum.
33:16Yield levers
33:17flights.
33:18They may be
33:19seeking the
33:19confidence that
33:20the generator
33:21was going to
33:21stay on line.
33:30At 3.12pm
33:32the pilots
33:34report the
33:34engine issue
33:35to the
33:35engineer.
33:36He came at
33:37around 4pm
33:38and got the
33:38right generator
33:39on line.
33:39Then at
33:414.30pm
33:42the crew
33:44runs the
33:44engines for
33:4530 minutes.
33:4730 minutes.
33:50Investigators
33:51consider the
33:51impact of
33:52starting engines
33:53filled with
33:54snow and
33:54ice.
33:55The heat
33:56from starting
33:57those engines
33:58would most
33:59likely have
34:00melted all
34:01the ice and
34:01snow in the
34:03upper chamber.
34:05And then
34:05gravity takes
34:06over and it
34:08all slides down
34:09landing here
34:10right in the
34:10path of the
34:11air intake.
34:12Which means
34:12all that
34:13water and
34:14slush would
34:15have frozen
34:16into ice.
34:21After the
34:22engines were
34:23turned on
34:23snow and
34:24ice inside
34:25the upper
34:26chamber likely
34:27melted and
34:28slid down to
34:29the air
34:29intake.
34:30When the
34:31engines then
34:32idled for
34:3330 minutes
34:33cold air
34:34entered the
34:35intakes
34:35refreezing the
34:37water and
34:37slush into
34:38ice.
34:40But is it
34:41enough?
34:42Was there
34:43enough ice
34:44inside the
34:44air intake to
34:45obstruct the
34:46airflow by
34:4778%?
34:49What else
34:49happened before
34:50the engines
34:50failed?
34:52The last
34:53thing they
34:54do before
34:55the engine
34:56failure is
34:56turn on the
34:57anti-icing
34:57system.
35:03Altitude?
35:032,200 feet.
35:07Let's put the
35:07anti-icing on.
35:11Anti-ice
35:12both on.
35:15And when the
35:16anti-icing is
35:16turned on to
35:17clear the air
35:17intakes, these
35:19veins would
35:20deploy, obstructing
35:21the airflow.
35:22When the
35:27anti-icing
35:28vein operates,
35:30airflow is
35:30reduced by
35:3250%.
35:33If
35:35accumulated
35:35ice reduced
35:37the airflow by
35:37another 28%,
35:39it would
35:40explain why
35:41the engines
35:41failed.
35:42The total
35:45blockage of
35:46the airflow is
35:47sufficient to
35:48cause the
35:50compressor to
35:51surge in the
35:53engine flaming
35:53out and the
35:54complete loss of
35:55power.
35:56We had two
35:57very well
35:58qualified crew
35:58on the day,
36:00and it was an
36:00alignment of
36:01circumstances that
36:02they could not
36:03see or foresee.
36:04Captain Mason
36:05and First Officer
36:06Dixon arrived at
36:07Edinburgh Airport
36:08long after the
36:09snowstorm had
36:10ended.
36:10Anti-collision
36:12beacon.
36:13Anti-collision
36:14beacon on.
36:16They had no
36:18idea that their
36:18engines were
36:19filled with
36:19snow.
36:24The snow had
36:25melted from the
36:25fuselage.
36:33Start master
36:34armed.
36:35Engine start
36:35sequence.
36:40They took all
36:41the right steps
36:42at take-off.
36:43They did
36:44nothing wrong.
36:46But what
36:46about after the
36:47engines failed?
36:53Could the
36:53pilots have
36:54found a way to
36:55save their
36:56plane?
36:57Airspeed.
36:58115 knots.
36:59We can't
37:00relight the
37:00engines.
37:02Compared to
37:02ditch.
37:02Ditch.
37:02Ditch.
37:02Ditch.
37:02Ditch.
37:02Ditch.
37:02Ditch.
37:03Ditch.
37:04Ditch.
37:04Ditch.
37:05Ditch.
37:05Ditch.
37:06Ditch.
37:06Ditch.
37:06Ditch.
37:06Ditch.
37:07Ditch.
37:07Ditch.
37:08Ditch.
37:10Ditch.
37:13Ditch.
37:14This is the
37:15final minute of
37:16the flight.
37:18Investigators
37:19returned to the
37:19flight data to
37:21determine if the
37:21crew followed
37:22proper procedures
37:23after losing
37:24engine power.
37:27Once the
37:28engines failed,
37:29the pilots needed
37:29to relight the
37:30engines to make
37:31it to land.
37:32Right.
37:33On a dual
37:33engine failure
37:34checklist.
37:38We have a
37:38double engine
37:39failure.
37:39Talks at zero
37:41on both
37:41engines.
37:44Dual
37:45engine failure.
37:46But the
37:47only checklist
37:47available was
37:48for a single
37:49engine failure.
37:54Dropping
37:54fast from
37:551,600 feet.
37:57Captain
37:57Mason probably
37:58knew that he
37:58didn't have
37:58time to
37:59relight the
37:59engines.
38:02Airspeed.
38:03115 knots.
38:05We can't
38:06relight the
38:06engines.
38:061,300 feet.
38:10110 knots.
38:14I had no
38:14choice but to
38:15ditch.
38:20Altitude.
38:211,500.
38:23Compared to
38:24ditch.
38:25Did the
38:25pilots do
38:26everything they
38:27could to
38:27ensure a
38:28successful
38:28ditching?
38:30Ditching,
38:31ditching.
38:31There's no
38:33ditching
38:34procedure for
38:34dual engine
38:34failure.
38:36Ditching with
38:37power then.
38:38We don't have
38:39flaps, so
38:40aiming for
38:41lowest possible
38:41speed.
38:42Without any
38:43engine power,
38:44the hydraulic
38:44systems would
38:45not be
38:45operating.
38:47The hydraulics
38:48drive the
38:48flaps, which
38:49means he had to
38:50touch down at a
38:50higher speed than
38:51he would like to
38:52do so.
38:52As I get
38:54closer, I'll
38:55increase the
38:55pitch to 90
38:56degrees.
38:57Anything I'm
38:58missing?
38:59No, sir.
39:01Without
39:01flaps, the
39:02only way you
39:03can reduce
39:03speed is to
39:04increase the
39:06angle, pitch
39:07of the
39:07aircraft prior
39:08to touch
39:09down.
39:10His actions
39:11were correct.
39:14Captain
39:14tried to
39:15reduce the
39:15impact with
39:16the few
39:16resources he
39:17had at hand.
39:17You hope
39:20it kisses
39:20the surface
39:21of the sea
39:21rather than
39:22thumping into
39:23it.
39:25Speed is
39:26110 knots.
39:27I'll get
39:27this as
39:28close to
39:28shore as
39:28possible.
39:30The slower
39:31you can go,
39:32the safer
39:32the ditching
39:33is likely
39:33to be.
39:36A successful
39:36ditching also
39:37requires level
39:38wings on
39:38impact.
39:39They nearly
39:40pulled that
39:41off.
39:41Airspeed.
39:48Airspeed is
39:4988.
39:50When the
39:51aircraft touched
39:51the water
39:52surface, one
39:53wing was three
39:54degrees lower
39:55than the other.
39:55That's a very,
39:56very small
39:57amount.
39:58From the time
39:59he identified
40:00the problem to
40:00the moment the
40:01plane hit the
40:01water, the
40:03captain nailed
40:04every single
40:05action correctly.
40:10They were very
40:11professional and
40:12they showed
40:12excellent
40:13prioritization.
40:15The captain
40:16especially, his
40:17experience clearly
40:18showed.
40:20Brace, brace,
40:21brace.
40:30I have immense
40:31admiration for this
40:32crew because they
40:34found problem
40:35after problem
40:36which they
40:37couldn't have
40:37foreseen.
40:39They handled the
40:40situation
40:41absolutely as
40:43well as any
40:44crew could
40:45possibly have
40:45handled it.
40:53This
40:53investigation
40:54reveals that
40:55checklists for
40:56double engine
40:56failure and
40:57ditching without
40:58power were
40:59missing from the
41:00Logan Air
41:01operation manual.
41:03The result of
41:04this accident was
41:05the tragic loss
41:06of two crew
41:07who had been
41:08doing their best
41:08to follow
41:09procedures.
41:11The airline also
41:12didn't adequately
41:13reflect the
41:14manufacturer's advice
41:15for protecting the
41:16engine's intakes
41:17during severe
41:18weather conditions.
41:20If the airline
41:21had followed the
41:23recommendations of
41:24the manufacturer
41:24and carried on
41:26board air intake
41:28bungs for the
41:29crew to use when
41:31the weather conditions
41:32demanded, then this
41:33accident would never
41:34have happened.
41:36The AAIB recommends
41:38that flight crews
41:38are educated about
41:39the potential of ice
41:41and snow buildup
41:42inside engines.
41:44I think the most
41:44important recommendation
41:45was that crews must be
41:48alerted to the fact
41:49that there's a
41:50possibility that snow
41:52would have built up
41:53in parts which are not
41:55visible to them by
41:56simply looking through
41:57the air intakes of the
41:59aircraft.
41:59This was a very
42:01regrettable accident.
42:03Their fate had been
42:04sealed by an alignment
42:06of circumstances that,
42:08whilst difficult to
42:09recognize, were
42:10avoidable.