Mayday (2013) s04e02 Episode Script

Falling from the Sky

High above the Indian Ocean disaster strikes.
The engine's on fire.
More than 10km in the air, all four engines of a British Airways 747 stop working.
Roger, declare emergency.
Mayday, mayday.
What has crippled their massive jet, threatening the lives of everyone on board? June 24th, 1982.
British Airways Flight 9 cruises through the sky over Indonesia.
In a few hours, the plane and all 263 people on board are scheduled to land in Perth, Australia.
Phyllis Welch and her daughter are seated in Cabin E at the very back of the enormous jet.
It's alright, Mum.
We'll get there.
(Grunts) We had already traversed at least two time zones.
We were very tired.
We had flown through Bombay, through Kuala Lumpur.
Hadn't been able to get much sleep, if any, and it was a dark, dark, pitch-black night.
Ahead of Betty and Phyllis, Charles Capewell is returning home to Perth, Australia, with his two boys, Chas and Stephen.
It was a good flight.
It was going well.
Leaving London was great and we were all eager to go home, and the two boys were eager to get back to Mum.
I thought, "Well, we'll be home in three hours.
Perth.
"There'll be Pat and we'll get in a taxi and we'll be home.
" While many of the passengers have been travelling for almost a day, the crew is fresh.
They took control at the last stopover in Kuala Lumpur.
Captain Eric Moody got his first taste of flying at the age of 16 when he took a gliding lesson.
He was one of the first ever trained on the 747.
Roger.
Check with Jakarta.
Jakarta control.
Speedbird 9 over Halim at level 3-7-0.
VOICE ON RADIO: Speedbird 9.
Roger.
First Officer Roger Greaves has been a copilot for more than six years.
Barry Townley-Freeman has been a flight engineer on these aircraft for just a little longer.
I'd not flown with Eric before, or Barry, and that was the first time we'd actually met on that flight.
As the jet flies over the city of Jakarta, it's cruising at more than 11,000m and has been in the air for an hour and a half.
Captain Moody checks his weather radar.
It shows smooth sailing for the next 500km.
Alright, Roger.
It's all clear.
Just keep your eyes open.
I'll be back in a moment.
Just got to use the loo.
Back in the cabin, many of the passengers have fallen asleep.
While Charles Capewell and his sons doze, an ominous haze appears above their heads.
It's still legal to smoke on passenger jets in 1982.
For the cabin crew, though, the smoke seems thicker than normal.
There seems to be a lot of smoke out there.
They begin to worry that a small fire may be smouldering somewhere on the plane.
Maybe someone lit up in the toilet.
Let's go see if we can find it.
A fire at 11,000m is a terrifying prospect.
If there is a blaze somewhere, the crew must find it immediately.
In the cockpit, the flight takes an unsettling turn.
Barry and I were just sitting there minding the shop, pitch-dark night of course, and then we started to get these pinpricks of light on the windscreen.
St Elmo's fire? I don't think so.
St Elmo's fire is a natural phenomenon that's sometimes seen when planes fly through highly charged thunderclouds.
But there aren't supposed to be any thunderclouds tonight.
Anything on the radar? No.
No.
It's clear.
I don't like the look of this.
Let's get a better look out there.
With the help of their landing lights, the two men are disturbed to see a thin layer of cloud surrounding their plane, even though nothing is showing up on their radar.
But at 37,000ft the normal thing you would anticipate would be high cirrus which is just a thin layer of cloud.
I think we'd better get the Captain back up here.
In the cabin, the smoke begins to thicken.
Stewards have been unable to figure out where it's coming from.
If there's a fire they can't find it.
There? Alright.
Well, go see that the passengers are comfortable.
It smelt like this sort of sulphuric electrical smell.
And I went on that flight deck expecting to hear that we had some electrical smoke somewhere on the aircraft.
But nothing was further from the truth.
When did it start? Just after you stepped out.
Anything on radar? No.
It's clear.
Not a cloud.
Oh, my Lord.
Look at engine 4! It's lit up somehow.
Captain.
Captain, have a look at number 1.
It's the same on my side.
None of the crew have ever seen anything like this before.
But the light show is just the beginning.
Their bizarre flight is about to take a terrifying turn for the worse.
Strange lights are striking the windshield of a British Airways passenger jet heading to Perth, Australia.
At the same time, the plane's engines are lit by a brilliant white glow.
Look at engine 4! It's lit up somehow.
This light show, if you like, had become more intense.
In fact, we ended up sitting there with two sheets of brilliant white light in front of us in place of the windscreens.
Inside the cabin, smoke has been growing thicker.
Chief Steward Graham Skinner has been organising an intense but quiet search for fire.
What's with all the smoke? SKINNER: There was smoke in the cabin.
It got really, really hot.
You were perspiring.
Literally drenched in perspiration.
And the acrid smoke was at the back of your throat, up your nose, in your eyes.
And you were rubbing this, and your eyes were running.
And it wasoh, not a very nice situation at all.
Flight Engineer Barry Townley-Freeman has been checking his instruments carefully.
He's smelled the smoke but so far has no indication that there's a fire in any of the plane's systems.
I can't find anything.
With one mystery confronting them, they're suddenly faced with a frightening new situation.
ALARM BEEPS Dad, the engine's on fire! There were HUGE flames coming out of the back of the engines - 20ft, some people said 40ft long.
What's going to happen? What's causing it? What are they going to do about it? As fire engulfs the engines, one of them revs loudly and flames out.
Engine failure.
Number 4.
Fire action.
Number 4.
- Checklist.
Power and gear.
- Set.
- Thrust lever.
- Closed.
- Start lever.
- Off.
Once one engine fails, you call for the drill to shut that one down.
You have drills for certain things so that you don't fly together as a crew forever.
You can fly with different people then and you can standardise the operations.
The instruments do not indicate a fire on the plane but the passengers can see flames erupting from the engines and stretching down the length of the 747.
The cabin crew begin storing anything that's loose.
They don't want dishes or bottles flying around the cabin if the plane begins to dive.
Don't worry.
It's just friction.
If I was misleading them then that was for a reason, because I didn't want them to get as upset as I felt.
I just couldn't believe it.
And, you know, this is going through my mind, yet I'm chatting to the passengers and chatting to the crew, saying, "Oh, yeah.
Nothing to worry about.
" "Yeah, it's just a little hiccup, you know?" So I thought (Chuckles) The 747 is more than 10km above the ocean.
Its engines appear to be burning and peculiar smoke continues to fill the cabin.
And thenthe unthinkable happens.
Number 2 engine's gone.
Alright, then.
Begin the engine shutdown.
No.
Wait! They've all gone.
All four engines have failed! MOODY: The other three just went out almost immediately.
And that's when it begins to be a serious emergency.
In a minute and a half, we've gone from four engines running normally to having none.
The 747 has plenty of fuel.
Yet somehow all four of the jet's engines have completely stopped working.
Roger, declare emergency.
Mayday, mayday, mayday.
Speedbird 9.
We have lost all four engines out of 3-7-0.
Mayday, mayday, mayday.
Speedbird 9.
We have lost all four engines With no engine power and no idea what has crippled their plane, British Airways Flight 9 begins falling from the sky.
Jakarta control.
Speedbird 9.
We have lost all four engines.
Now out of 3-6-0.
First Officer Roger Greaves issues a mayday but he has trouble getting his message across.
MAN ON RADIO: Got a problem? Jakarta control.
Speedbird 9.
We have lost all four engines.
Repeat - all four engines.
Now descending through flight level 3-5-0.
RADIO: Speedbird 9, you have lost number four engine? This idiot doesn't understand! Jakarta control.
Speedbird 9.
We have lost all four engines.
Repeat - all four engines.
Now descending through flight level 3-5-0.
The air traffic control at Jakarta unfortunately seemed to have a slight problem in understanding what we actually were saying.
Only when another plane nearby relays the mayday call do controllers in Jakarta understand.
Now descending through flight level 3-5-0.
VOICE ON RADIO: Speedbird 9.
All four engines out.
Understood.
As far as the crew knows, no 747 had ever lost power to all of its engines before.
The crew has to find out why it's happening now.
I think we've cocked something up.
We were concerned and worried that we'd done something wrong, you know, to cause the whole thing.
All three of us felt exactly the same and it was a personal guilt in the sense of, "What have I missed? "What have I done wrong?" You know, because this kind of thing doesn't happen.
High above the Indian Ocean, all four engines on a British Airways 747 have stopped working and the crew has no idea why.
While not built for gliding, even without its engines a 747 can travel forward 15km for every kilometre it drops.
With no power, Flight 9 has started a long, slow fall.
Some 10km above the ocean, the crew has less than half an hour before they smash into the sea.
When they all stop, you go into automatic mode, obviously.
We had practised this drill on the simulator many, many times.
And that's very good and all very well as long as when it happens to you for real, what happens on the aeroplane is mirrored by what happens to you in the simulator.
And I'm afraid that wasn't so.
In the simulator, when all four engines stop, the autopilot turns off, but high above the Indian Ocean, Captain Moody sees that his autopilot is still on.
We were, all three, confused and concerned that what was happening to us wasn't what we'd been told would happen to us.
- Alright.
Begin restart drill.
- Set.
In the heat of the situation, they have no time to figure out why the autopilot is still on.
On.
Anything? ANYTHING? - No! Again.
Alright, then.
From the top.
Battery.
Check.
On.
- Crossfeed valves.
- Open.
- Fire switch.
- In.
The standard restart drill takes up to three minutes to complete.
Plunging from the sky, the crew has fewer than 10 chances to get their engines going before they run out of time.
Lever - on.
Come on! Again, gentlemen.
- Alright.
From the top.
- Battery.
- Check.
On.
- Crossfeed valves.
- Open.
- Fire switch.
- In.
At 10,000m, Captain Eric Moody decides to turn the plane back toward the closest airport, Halim, just outside Jakarta, but even that is too far away if he can't get at least some of the engines going again.
Jakarta, Speedbird 9 turning left back to Halim.
Out of 3-0-0.
RADIO: Speedbird 9.
Radar cannot see you.
Squawk alpha 7,700.
Air traffic control asks them to transmit the emergency transponder signal.
Jakarta.
Speedbird 9.
We are already squawking 7-7-0-0.
Now the crew is flying back to an airport that can't find them on radar.
Without the constant rumble of the engines, the cabin is quiet.
Some of the passengers feel the plane beginning to descend.
But without communication from the cockpit, they can only guess.
What's going on? What's the problem? It's just a technical fault.
I've been through much worse, let me tell you.
Everything will be fine.
I think if I'd have sat down and really thought of exactly what was happening, I don't think I would've ever got up again.
One steward came up to us and said, "Are you two ladies alright?" And "Yes," we said, "we're fine," which was an absolute lie.
But that's how it was.
It seemed absolutely vital not to panic.
Captain Moody can't restart the engines unless he can keep the plane flying between 250 and 270 knots.
But the airspeed indicators aren't working.
Captain, I've got 320 knots on my side.
Well, I've got 270.
Bloody hell, that's a 50-knot difference.
I'll change the speed.
Falling from the sky with no engine power, the crew now have no idea how fast they're going.
But to have the best chance to restart the engines, Captain Moody has to have the plane flying at the right speed.
So from that point onwards, Eric then varied the speed through just about a 100-knot range, hoping that at some point or other, coincidental with us putting the fuel into the engines, that we would actually be at the right speed.
To change speeds, Captain Moody turns the autopilot off.
Then he slowly pulls the nose of the jet up to slow it, and then pushes it down to increase his speed.
The upsetting roller-coaster movement adds to the panic felt in the cabin.
- ALARM BEEPS - Pressure warning, Captain! We're at 10,000.
Pressure warning? That's not supposed to do that.
And a warning horn went off.
This didn't ever happen in the simulator in this exercise.
So it was a bit of a surprise to us.
As well as providing electrical power, the engines on a jumbo jet help keep the cabin pressurised.
With the engines not working, of course, the air wasn't being pumped in.
So, gradually, the pressure was leaking away.
With all four engines gone, the pressurised air is rapidly seeping out.
The thinning level of oxygen makes passengers gasp.
- (Coughs) - WOMAN: What's going on? The crew reach for their oxygen masks.
But First Officer Greaves can't get his mask to work.
My oxygen mask, you know, that was a problem I could've done without.
It was stowed above my head.
And when I pulled the oxygen mask down, the mask and the tube became separated.
The Captain must make a difficult choice.
If he continues to descend slowly, it will get increasingly difficult for First Officer Greaves to breathe.
I said, "Look, if we get down to 20,000ft quickly, "we can all take our oxygen masks off, "we can talk and we're back as a crew again.
" We had to actually increase the rate of descent to descend to a lower altitude quicker, which, in the circumstances, was something that we wouldn't really have chosen to do.
So then I dived the aeroplane and got rid of about 6,000ft in a minute.
The loss of cabin pressure and the steep dive have another terrifying consequence.
(People cry out) I've seen a few movies on the planes.
And, you know, once that happens, you know you're in serious trouble.
The oxygen masks came down and we put those to our faces, as had been described in the drill, which, fortunately, we had been observing at the beginning of the flight.
But it seemed that the oxygen supply was not working.
- Is yours working? - No.
I'm not getting anything.
The cabin crew try to use the public address system to explain what's going on.
But it's not working.
Chief Steward Graham Skinner makes do with a low-tech backup.
(Over megaphone) Can you hear me? We're having a small problem with the public address system.
So, if you would, place your masks over your mouth and nose and breathe normally.
As the passengers struggle with their masks, Captain Eric Moody is running out of options.
If his engines don't start soon, he'll have to turn his jet around and try landing on the open ocean.
High above the Indian Ocean, the seemingly impossible has occurred.
All four engines on a British Airways 747 have stopped working and the crew has no idea why.
First Officer Roger Greaves manages to fix his broken oxygen mask, but he's still frustrated by engines that won't start.
Alright, Barry, let's start the restart drill.
- Ready? - Set.
- Battery.
- Check.
On.
- Standby power.
- On.
Anything? - Come on.
Anything? - No.
Alright, then.
Let's do it from the top.
- Battery.
- Check.
On.
First Officer Greaves and Engineer Barry Townley-Freeman have actually shortened the standard restart drill.
It's giving them more chances to get the engines going.
But so far nothing is working.
Come on, you old sod.
GREAVES: The process that we were going through the whole time was just continuous.
We hadn't had any success with the drill at all, despite all the efforts we were putting in.
But it was the only thing we had left to cling onto, so that's what we did.
- From the top again.
Battery? - Check.
On.
MOODY: I have no idea - I don't think any of us have - how many times we tried to restart those engines.
If I say 20, I would think that's too low.
If I say 50, I would think that's probably about right.
As the plane falls lower and lower, Captain Moody faces a brutal choice.
A mountain range cuts across the island of Java between his plane and the airport.
He knows he has to be at least 3,500m high to clear it.
But if his engines don't restart soon, they won't make it.
At this rate, it will crash in a matter of minutes.
It's just a question of where.
Captain Moody decides if the engines don't restart soon, he'll turn back towards the ocean and try landing on the water.
Alright, are we getting something? It's not starting.
MOODY: I knew it was so difficult to land aeroplanes on the sea, even when you had everything going for you.
And I thought that, well, we haven't got much going for us here.
I'd never done it before.
Hiding his concern, Captain Moody addresses the passengers and crew.
Ladies and gentlemen, this is your captain speaking.
We have a small problem.
All four engines have stopped.
We're doing our damnedest to get it under control.
I trust you are not in too much distress.
- Well? - Nothing.
It's not starting.
Alright, from the top then.
Battery.
Check.
On.
- Standby power.
- On.
Finally, Captain Moody has to decide - carry on and likely crash into the mountains or turn around and ditch into the sea.
I don't know how to swim.
I couldn't swim anyway, so I thought, "I'm doomed anyway.
" And I just hoped that maybe one of the passengers might help the two boys, to make sure they could stay afloat.
- Well, anything? - No.
Alright, then.
From the top again.
Battery.
We had very few chances left of starting the engines before having to turn out to sea again because we wouldn't have been able to clear the mountains on the south coast of Java.
(Passengers chatter nervously) - Start lever.
- Cut off.
- Fuel pressure.
- Unavailable.
Standby ignition on.
And then, as suddenly as it had stopped working, the fourth engine roars back to life.
Engine 4, back online.
CAPEWELL: Then all of a sudden there was this sort of .
.
like somebody giving the aeroplane a punch from underneath.
And then I realised that there might have been an engine who's "Brrrm!" Oh.
Oh, my God! Look.
The noise that a Rolls-Royce engine makes when it starts up is a low rumbling noise, and it was just, well, it was wonderful to hear it.
A 747 can fly with one engine.
But Captain Moody knows that just one engine still won't give him enough power to clear the mountains.
The glass now is half full.
It's not half empty.
We are now in with a real chance, and I'll tell you what, the three of us would've dragged that aeroplane around the whole island of Java.
As the plane falls past 4,000m, another engine coughs and comes back to life.
Engine 3 back online! It's followed quickly by the final two.
I don't believe it! Engines 1 and 2, both back online! (Laughs) From almost certain disaster, the crippled jet is now under full power.
- (Passengers applaud) - Oh, my God, Mum! I realised then that we could make it back to .
.
not to Perth, but to an airport.
That's all we wanted, was to land on the earth and, you know, be part of the living again.
'Cause while we were up there, we were dead.
(Laughs) Jakarta.
Speedbird 9.
We are back in business.
All four running.
All four running.
This time local controllers have no trouble understanding the message.
RADIO: All four engines serviceable again.
Confirm continuing to Halim.
Affirmative.
Affirmative.
(Laughs) During a calm flight to Australia, all four engines of a British Airways 747 suddenly stop working.
After a long, terrifying descent, the crew managed to restart the engines, Engines 1 and 2, both back online! We say, "Right, let's get this thing on the ground quickly as we can.
" Ladies and gentlemen, this is your Captain speaking.
We seem to have overcome that problem and have managed to start all the engines.
(Passengers laugh and applaud) (Sighs) MOODY ON P.
A.
: We are diverting to Jakarta and expect to land in about 15 minutes.
Captain Moody begins climbing, putting plenty of room between his plane and the mountains below.
But as he does, the strange lights he saw when the crisis began reappear in front of the jet.
As soon as we got to 15,000ft, this St Elmo's fire started again.
I'm not slow, so I said, "Let's get out of here quickly.
" But before he can descend very far, the plane is stricken again.
Engine 2 is surging.
Oh, no! Not again! The whole aeroplane was shaking.
It was just going, "Bang! Bang! Bang!" The engines backfire violently.
The Captain must make another fateful decision.
Begin shutdown drill.
- Checklist, power and gear.
- Off.
- Thrust lever.
- Closed.
We were reluctant to do it, as you can probably understand, but, you know, that was it.
So we were back on three engines.
Now, I'm not a coward, but when you've had four engines going, no engines going, you get four going, and show me any pilot that will quickly shut down that engine.
'Cause you're worried that they're all going to stop again.
Jakarta.
Speedbird 9.
Leaving 1-50-4-1-20.
We are now on three engines.
As the plane closes in on the airport, First Officer Greaves thinks the windshield is covered in moisture, making it hard to see through.
And I said to Eric, "It's a bit misty out there.
" So we turned the blowers on, you know, like demisters on your car, to try and clear that.
That didn't work.
I used the windscreen wipers and that didn't work.
Somehow the glass itself has been badly damaged.
For some reason, I looked out the edge of my windscreen.
And about a two-inch strip down the edge on the left hand side, I could see much more clearly.
But I couldn't see anything much out the front.
It was getting more and more opaque the nearer and nearer we got to the lights.
The crew get a final unwelcome surprise.
Equipment on the ground that helps them descend at the proper angle isn't working.
RADIO: Jakarta ATC.
Be advised, our glide path is unserviceable.
The localiser, which gives you the left and right of the runway centre line, that was working.
But the glide slope, which gives you the actual profile for the descent, was not working.
After all the troubles they've been through, now the crew has to land their plane manually.
We then continued, with Eric flying the localiser and me calling out the distance and the altitude that he should be at.
300ft, Captain.
GREAVES: So he was then able to adjust his rate of descent to what I was telling him, as far as the glide slope was concerned.
GREAVES: 200.
RATTLING 150ft, Captain.
50ft.
30ft.
WHEELS THUD ON RUNWAY - Oh, my God! Oh, my God! - (Cries) (All applaud and cheer) Dad, we're on the runway! Reverse.
APPLAUSE AND CHEERING CONTINUES 90 knots.
80 knots.
(All laugh) We're down.
I could really go for a cold soda.
And the aeroplane just landed itself.
It seemed to, anyway.
It kissed the earth.
It was beautiful.
That'sthat's amazing.
Huh! Safely on the ground at Halim Airport in Jakarta, passengers celebrate the end of a harrowing ordeal.
They also want to know what happened.
No fire had been found, so why had smoke filled the cabin? How could all four engines have stopped at nearly the same time? What were the strange lights that surrounded the plane? In the cockpit, the flight crew are relieved but also concerned that they might be at fault.
The first thing that we did, having parked the aeroplane and shut it all down, was to then go through all the paperwork to see if there was possibly anything anywhere in it that might have given us any pre-warning of some sort of phenomenon that caused what happened to us.
Every time.
'Cause it's gonna come back to us.
The damage to the 747 is extensive.
From the outside, the crew realise that their windshield had been deeply scratched.
They see bare metal showing through where the paint has somehow been stripped away, and they still have no idea why any of it happened.
When investigators uncover the cause of the disaster, Flight 9 changes pilot training around the world.
During a calm flight to Australia all four engines of a British Airways 747 suddenly stop working.
(Both gasp) After a long, terrifying decent the crew manage to restart the engines and land.
Wow.
That'sthat's amazing.
They spent an excited and largely sleepless night in Jakarta before returning to Halim Airport to inspect their plane.
ERIC: And we went back the next day to look at it in daylight.
The aeroplane had lost its sheen and in some places it had been sandblasted quite well and all the decals and the paint had come off.
There really was very little to see until they stripped the engines down.
The engines were manufactured by Rolls-Royce.
Their investigation was led by a former engineer, Malcolm Grayburn.
Three of the engines were removed in Jakarta following the incident and were ferried back via cargo aircraft to London, Heathrow, and then transported to South Wales where the engines were, in fact, stripped down into piece parts.
And it was there that I got involved.
Grayburn was stunned by what he saw.
Much of the engine was badly scratched and scored.
We did do a forensic analysis of the engines and we did record it all, in terms of photographic analysis, and also we did a lot of laboratory analysis.
Grayburn discovered the engines were choked with fine dust, pieces of rock and sand.
When it was closely studied, they learned that the debris was clearly volcanic ash.
Days after their harrowing flight, the passengers and crew learned that the night they were flying there'd been a major eruption of the Mount Galunggung volcano, located just 160km south-east of Jakarta.
Tom Casadevall is Director of the US Geological Survey and has studied the Galunggung volcano.
Indonesia is the world's most volcanically active country.
It has more than 130 historically active volcanoes, meaning volcanoes which have erupted in the last several thousand years.
Galunggung erupted explosively early in the 1980s.
In April, May, June of 1982, the eruptions became increasingly more powerful.
The eruptions were large and the damage was extensive.
More than 60,000 people were evacuated from the area around the mountain.
The night Flight 9 flew nearby, the volcano erupted again.
As the ash cloud rose more than 15,000m into the night, winds pushed it to the south-west, right into the path of British Airways Flight 9.
Never before had a volcanic cloud seriously affected an aeroplane.
Could the ash really have crippled this flight? Roger, declare emergency.
Mayday.
Mayday.
Mayday.
Speedbird 9.
We have lost all four engines.
CASADEVALL: Unlike ash that you might see in a chimney or after a fire in a forest, this is not soft material at all.
This is very fine ground-up particles of solid rock and minerals.
This material is very, very abrasive.
It's very angular in shape.
If you were to see it under a microscope you would see very sharp angles.
And so that's what caused the abrasion.
In addition to sandblasting the windshield and all the leading edges of the plane, could the ash cloud explain all the other strange phenomena the passengers and crew had experienced? Remember, the aircraft is moving in close to 500 miles per hour as it's flying into that cloud.
Even though it's a very fine material, it can still cause abrasion and friction on the skin of the aircraft.
Because it's such a dry environment up there, that frictional electrification produces the glow that we refer to as Saint Elmo's fire.
The electrification also caused the interference in communication experienced by the crew.
RADIO: Speedbird 9, you have lost number 4 engine? Some of the volcanic ash that was sucked in and ground up by the engines was also blown into the plane, and when passengers and crew saw it swirling through the cabin they feared the worst.
You're a passenger.
You're looking out the window.
Suddenly you start breathing this sulfureous, sulfur-laden air in the cabin and it probably is a choking, probably a shocking sensation.
It's essentially a house-of-horrors-type situation.
While the volcanic ash caused the visible scarring, filled the plane with smoke and fouled communications, could it cause the engines to flame out as well? A turbo-fan jet engine works by sucking in enormous amounts of air.
The air is then highly pressurised by the engine's compressor.
This tightly-packed air is mixed with fuel and ignited.
The force of this reaction propels the jet through the sky.
The temperatures in the combustion chamber, where this ash is flowing through, are around 2,000 degrees Centigrade.
And so the volcanic ash, we know, melts at about 1,300-1,400 degrees.
But when the liquid ash reached deeper into the engine it cooled slightly, turning into a sticky, molten goo.
It attached itself to the engine and began choking it.
We got a fundamental disturbance of the airflow in the main core of the engine, which caused the engine to backfire, and the engine's flamed out.
And that was the cause of the problem.
Backfires occur when the engine isn't burning cleanly.
The engine's on fire! There's too much fuel and not enough oxygen.
Engine failure.
Number 4.
Fire action.
Number 4.
Check list.
Power and gear.
On Flight 9, the backfires were the cause of the enormous jets of flame many passengers saw behind the engines.
After struggling against the choking effects of the ash cloud, the engines on board the 747 flamed out.
What Grayburn found next was that a remarkable piece of chemistry saved the plane.
As soon as you came out of the volcanic ash and the engines were not running, remember, so everything cooled down.
It was enough for this stuff to break off and allow the engines to restart.
When enough of the molten ash was gone the engines were clear again and Townley-Freeman's frantic efforts to restart them paid off.
Engine 4 back online.
We have learned quite a bit and we've incorporated this learning into pilot training.
Pilots now, for example, know what signs to look for when they might be in an ash cloud.
And those signs include the odour of sulfur in the cabin, dust accumulating in the cabin, and if you're at night, you might look out and see the frictional electrification of the Saint Elmo's fire on the leading edges of the aircraft.
Another important lesson learned from Flight 9 is that volcanic ash clouds do not appear on normal weather radar, which reflects water.
Since the clouds are dry, they're all but invisible to radar.
That knowledge has led to better communications between the geologists that study volcanoes and the international airlines that fly over them.
The crew of Flight 9 was showered with awards and commendations in the months after their incredible night.
I thought the airmanship displayed by this crew during this event was absolutely fantastic.
The way that they managed to guide this aircraft back down to a safe landing after having been through such extreme circumstances It was fantastic the way they recovered this aircraft.
Absolutely brilliant.
For everyone on board Flight 9, the terrifying plunge through the skies had a lasting impact.
Betty Tootell was so struck by the events of that night that she wrote a book about the ordeal.
TOOTELL: This was an event which was unique in aviation history and it seemed to me absolutely vital that it should be put on record and I wondered who was going to do this.
But no sooner had that thought entered my mind than I thought, "I'm going to do that.
" Tootell would also end up marrying a man she met on the flight - James Ferguson.
Charles Capewell and his two sons made it home two days after they touched down in Jakarta.
25 years later, both Chas and Stephen still live in Perth.
CHARLES: Our time hadn't came, and that was it.
From then on I took a different view of life.
When your time comes, there's nothing you can do, but you can still hope.
And we hoped and we got out of it.
Not long after their fateful flight, Captain Eric Moody created the Galanggung Gliding Club.
Every member of the crew and all passengers were automatically admitted to this exclusive group.
The survivors of British Airways Flight 9 happily stay in touch to this day.

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