Mayday (2013) s04e10 Episode Script
Ghost Plane
MAN: Helios 522, do you read? VOICEOVER: High above Athens fighter jets track a 737 as it circles the city.
522, do you read? Over.
There's no answer from the passenger plane, but there is someone at the controls.
More than 100 people are on board.
Everybody's mind was going to a hijack or 'terrorists'.
There is one person moving in the cockpit.
Repeat, there is What happened to the crew and passengers? 522, do you read? Over.
And who is flying the plane? Helios 522, do you read? Over.
Early morning, August 14, 2005.
The cabin crew of Helios Airways Flight 522 are preparing for their trip from the island of Cyprus to Athens, Greece.
Sure is a beautiful day.
Maybe I shouldn't have come in.
Andreas Prodromou is 25.
He isn't supposed to be working today but he's taken the flight to spend some time with his girlfriend, who also works for Helios.
It's the sort of day I'd like to be up flying.
Oh! You will, Andreas.
Prodromou is a flight attendant now, but he has bigger plans.
One day he wants to fly for Helios.
(Man speaks Greek) TRANSLATION: His dream was to become a professional pilot.
Personally, I wanted him to stay in the family business.
We often talked about this.
We've got company.
- Stay warm at the back.
- I will.
See you in Athens.
In the cockpit, the flight crew is occupied with the daily routine of preparing their jet for take-off.
It's bright today.
Captain Hans Merten is an East German, a contract pilot hired by Helios for the busy holiday season.
Are you almost through? Pardon? Areyoualmostdone? Nearly.
His copilot is from Cyprus.
Pampos Charalampous has been working exclusively for Helios for the last five years.
Before beginning any flight, crews are required to perform dozens of checks on various pieces of on-board equipment.
It's a routine, but necessary, procedure.
Doors closed.
Sorry, could you store trays? Put your seatbelt on.
Helios is a charter airline with low-cost fares to Greece.
It's a summer weekend and the plane is filled with families.
In all, there are 115 passengers on the morning flight.
If you need any more help let me know.
We're just about to take off.
They are low-fare, no frills.
They don't even serve you refreshments during small sorts of flights.
But they offer another possibility for the budget-minded traveller.
Paris Dimitriou and Maria Rikkou are travelling to the Greek island of Paros.
They've just got engaged.
Ah, they booked they booked this holiday a month, or more than a month ago.
It was like a honeymoon for them.
CAPTAIN: Flight attendants, please take your seats.
Prepare for take-off.
See you later.
Just a few minutes after 9:00 in the morning Helios Airways Flight 522 lifts off into the bright sunshine.
Area Control, this is Helios 522.
Request cruising at 3-4-0.
AIR TRAFFIC CONTROL: Helios 522, you are cleared to climb to 340.
Have a good day.
Set 340.
Minutes into the flight, the plane is still climbing towards its cruising altitude.
Suddenly an alarm blares in the cockpit.
- LOUD BEEPING - What is it? BEEPING CONTINUES The take-off config warning? The flight crew is confused.
The take-off configuration alarm normally only sounds on the ground.
It tells pilots their jet isn't ready for take-off.
The crew doesn't know why it's sounding now.
Uncertain what the problem is, the captain radios the Helios Operations Centre at Larnaca Airport, back in Cyprus.
Operations, this is Flight 522, over.
Flight 522, what can I do for you? We have a take-off config warning on.
Pardon? Our take-off config warning is on.
I'm sure it's nothing.
I'll let you know when we level off.
With the first alarm still beeping in the cockpit, things become even more confusing.
Their Master Caution alarm goes off.
It could indicate that some systems on board are overheating.
We now have a Master Caution.
I'll get you an engineer.
522, just a minute.
I find him very hard to understand.
His accent is quite thick.
Flight 522, what can I do for you? ALARM BEEPS The ventilation cooling fan lights are off.
Sorry, could you repeat? While the pilots and ground engineers try to troubleshoot the two alarms, most passengers have no idea there's a problem until (All gasp) Everyone, stay calm.
Please remain seated.
Everyone, please put the oxygen masks on completely over your mouth and nose.
MAN: The protocol was immediately to secure yourself, grab an oxygen mask, stay in your seat.
If you can help passengers without getting up you could help them and you should help them, but you would not risk the safety of any cabin crew member to go and help a passenger which is five or six rows further up.
MAN: Their procedure would be to grab their mask, don it, and wait for the aircraft to level off or commence with a descent.
No-one in the cabin knows what the problem is.
They're waiting for information from the cockpit.
The pilots are unaware that the oxygen masks in the cabin have dropped and they still don't know why their take-off configuration warning is on or why their systems are overheating.
Both of my equipment-cooling lights are off.
This is normal.
Can you please confirm your problem? But the engineer on the ground is struggling to get a clear picture of what's happening in the air.
They are not switched off.
Can you confirm that the pressurisation panel is set to 'auto'? Where are my equipment-cooling circuit-breakers? Behind the captain's seat.
Can you see them? What's going on? There's something wrong with the electrics on 522.
LAZAROS: I had something to pick up from operations, so I was there.
I figured, "Oh, not again.
One of our problems.
" SoI left.
Well, good luck.
The problem doesn't seem serious.
But as the plane continues to climb passengers still haven't received any information from the cockpit.
Helios 522, can you see the circuit-breakers? And now the engineer on the ground loses contact with the aircraft.
Helios 522.
Can you hear me? It's less than 30 minutes after take-off and Flight 522 is still on course.
The plane is high above the Mediterranean Sea and headed straight towards Athens.
August 14, 2005.
A Helios Airways 737 with 121 people on board is circling in the sky near Athens.
Helios 522.
Can you hear me? Shortly after leaving the island of Cyprus two different alarms had been triggered on the plane.
The flight crew was trying to solve the problem with the help of ground engineers.
But now radio contact with the plane has been lost.
Air Traffic Control can't get any response from the captain or copilot.
The flight to Greece normally takes an hour and a half.
But the passenger jet has been in the air for over two hours, circling in a holding pattern.
MAN: We heard that there was an aeroplane which was flying to the Greek territory and had no communication.
Everybody's mind was going to a hijack or to terrorists.
More than 3 million people live in Athens.
A plane slamming into the city could cause an incredible loss of life.
FAITHON: This is a runaway aircraft.
It's a possible hijacking or it's a possible terrorist act, so let's involve the military.
The Greek Air Force scrambles two of its most sophisticated fighter jets to investigate the Helios plane.
MAN: Helios 522, do you read? Over.
But the pilots aren't getting any response.
One of the jets flies closer to the cockpit.
Someone is in the copilot's seat, slumped over the controls.
But there's no sign of the captain at all.
The fighter pilot radios Air Traffic Control in Athens.
Athinai ACC, there is one figure in the cockpit of Helios 522.
He appears non-responsive.
Athinai ACC, checking the cabin.
He can see passengers in their seats but none of them reacts to the presence of the jet.
Then the pilot sees someone moving in the cockpit.
Athinai Control, there is one person moving in the cockpit of Helios 522.
Repeat, there is one person inside the cockpit.
Helios 522, do you read? Over.
Helios 522, over.
Flight HCY 522, this is Athinai Radar Control.
The F-16s continue shadowing the jet but there's no response at all from the cockpit.
One of them was actually in the shooting position, behind the 737.
The other one was nearby the cockpit, and he was trying to communicate visually with the person in the cockpit.
Suddenly the 737 turns left and begins to quickly descend.
Athinai ACC, Helios 522 turning sharply.
Following down.
For more than 10,000m the plane drops towards the ground.
There is no structural failure.
There is no fire.
There is no problem, obvious problem, from the external view, with the plane.
AIR TRAFFIC CONTROL: Helios 522, over.
Do you read? Helios 522, do you read? Over.
ALARMS BEEP Then, 2,100m above the ground, the person in the captain's seat acknowledges the fighter jet for the very first time.
But no words are exchanged.
Neither the fighter pilot nor local air traffic control can make radio contact with the jet.
Just after 12:00, almost three hours after it took off from the island of Cyprus, Helios Flight 522 slams into the ground.
Athinai ACC, Helios 522 is down.
Repeat, Helios 522 is down on Grammatiko Hill.
Over.
Fire and rescue workers rush to the crash site.
There are no survivors.
Flight attendant Lazaros Temetzian is stunned by what he hears at the company's Operations Centre.
It was the most chaotic scene I've ever seen.
When I went back our Operations Controller said that he'd lost the aircraft.
And his eyes He was starting to cry.
Helios is a small company with just three jets.
Members of the cabin crew have been working together for years.
For Paul Symeonides, news of the crash is particularly terrifying.
He's a flight attendant for the airline, and so is his fiancee.
I think that must've been the worst 30 minutes of my life, following that first image, because Victoria was flying that morning to Glasgow.
I had everyone and his brother, every person we knew was calling me up to find out if I'm alive, if Victoria's alive, what happened, why it happened.
WOMAN: At first we said, "It takes one hour and half to go to Greece, "so probably is not that plane.
" And took about two or three hours later to know that Paris and Maria was on the plane that crashed.
Andreas Prodromou's father didn't know his son had been called to fill in on Flight 522.
(Man speaks Greek) TRANSLATION: I was told that Helios aircraft was lost by radar and air controllers couldn't contact it.
I got worried.
I called Andreas's phone - he always had it on - and, unfortunately, he wouldn't answer.
After that phone call, I felt as if the ground was pulled out from under my feet.
It's the worst air crash in the history of Greece.
Most of the 121 victims are from Cyprus.
The small island nation declares three days of mourning following the crash.
It's an eerie disaster.
For over an hour air traffic controllers watched the passenger jet fly in radio silence closer and closer to Athens, with no idea what was happening inside the jet.
Now, piece by piece, investigators are trying to find out.
MAN: So we climbed over the hill and there we were, you know, facing this situation, which was beyond anyany description.
I saw a great area in front of me which was burning.
It was black.
Burning.
People spread.
Pieces ofof the aeroplane.
TRANSLATION: It is a truly nightmarish sight.
I hope that I never experience it again.
It was terrible.
Just terrible.
August 14, 2005.
Athinai ACC, Helios 522 is down.
Investigators immediately start looking for the cause of the crash.
In the early days, their efforts take a frustrating turn.
They recover the box containing the cockpit voice recorder .
.
but the recorder itself has been thrown clear.
It was difficult for us, because we first found the case of the CVR very badly damaged.
And we could not find the you knowthe machine itself.
Investigators need to know what happened to the pilots.
Without the cockpit voice recorder, they have little to go on.
So keep looking.
Let's hope we can find it.
Bodies recovered from the wreckage are brought to the offices of Athens' Chief Coroner.
Autopsies add more mystery to the case.
Everyone on board the plane was alive at the time of the crash.
DR KONTSAFTIS: There were scenarios at the time that they had all died in midair.
But the truth .
.
they did not die from inhaling a toxic substance in the aeroplane or from an explosion.
These people died on impact.
(Speaks Greek) But if the passengers were alive the entire flight, why didn't the pilot of the fighter jet see any activity inside the cabin? And who was at the controls as the jet circled over Athens? When investigators find tissue samples in the remains of the cockpit, they make a stunning discovery.
The person at the controls of the plane when it crashed was Flight Attendant Andreas Prodromou, a last-minute addition to the cabin crew.
But why was he in the cockpit? Was he trying to save the plane? Or did he deliberately fly it into the ground? Several days after finding the outer case of the cockpit voice recorder, investigators find the recording itself.
When Chief Investigator Tsolakis listens to the final moments of the flight, it answers a vital question.
(Faintly) Mayday.
Mayday.
This was no terrorist act.
Flight 522 Prodromou was calling for help.
Mayday.
Mayday.
Tsolakis hears five separate 'maydays' on the tape, even though none of them were heard by the air traffic controllers.
From the first moment that they saw someone in the cockpit, believe me, I was certain it was Andreas.
He wasn't a coward.
He knew something about planes and he had the capacity to do something.
In fact, Prodromou had his commercial pilot's licence.
It was the first step towards his goal of becoming a captain for Helios.
It's the sort of day I'd like to be up flying.
Oh, you will, Andreas.
But all of his training wouldn't have helped save the jet.
When he was seen at the controls, Flight 522 had been in the air for almost three hours.
And the reason the Helios plane seemed to veer away from the F-16s following it was because its left engine was out of fuel.
No matter what caused the alarms to sound, the ultimate reason for the crash was simple.
The FDR and CVR gave us absolute proof that the plane ran out of fuel.
And this was the cause of the crash.
Scheduled as a 90-minute flight, the plane didn't have enough fuel to stay in the air for over three hours.
But why had the plane flown so much longer than it was supposed to? Tsolakis now knows who was in the cockpit of the plane and why it crashed.
But to fully understand the mystery he needs more information.
ANDREAS: Mayday.
His investigators uncover a suspicious history of maintenance issues with the Helios jet - issues that could help explain what happened on Flight 522.
Less than a year before the crash, the same aircraft had suffered a rapid decompression.
LOUD BANG (People scream) Lazaros Temetzian worked on that flight.
LAZAROS: I was in the back of the aircraft at the time.
There was a loud metallic bang, a clanging sound, and the oxygen masks dropped in the cabin.
Every step I was taking was difficult.
It was hard to move, hard to breathe.
In fact, I was I was starting to pant.
I was panting for air.
As the plane began an immediate descent to 3,300m, all Temetzian could do was remain strapped in and wait.
Once the plane reached a safe altitude, Temetzian inspected the rear door and was shocked by what he found.
I had noticed that the aft service door was not fully locked.
The hinges on the top and the bottom of the door were kind of displaced.
I could pass my hands right through.
There were no injuries and the plane made an emergency landing and the door was inspected.
But this wasn't the only problem crews had with this plane.
We would record faults in the cabin logbook constantly.
And nothing would be done to rectify even these small little problems in the cabin.
Engineers would take months to rectify even the slightest problem in the cabin.
There were more recent problems as well.
A Helios ground engineer tells Tsolakis that on the very day of Flight 522 the 737 had another problem with its back door.
When we checked the flight log for the trip we saw that we'd have to do some unscheduled maintenance.
The plane had arrived in Cyprus just after midnight on August 14.
The cabin crew had heard loud banging noises and saw ice on the rear service door during the flight.
It was scheduled to take off again, just hours later.
Soon after it landed, engineers began checking the problem.
To make sure there's nothing wrong with the seal on the door, the engineers run a pressurisation test.
During normal flight, a plane's engines force air into the cabin.
To ensure oxygen circulates during the trip, small valves in the rear allow some of it to leak out.
MAN: A pressurised aeroplane, essentially, is sort of like a pressurised can.
Well, we pressurise the aeroplane so that the people inside can survive the environment that the aeroplane likes to operate in.
Switching digital pressure control unit from auto to manual.
Without the jet's engines running, the engineer uses the plane's auxiliary power unit to force air into the aircraft and the cabin is pressurised for several minutes.
BILL: It's like looking for a leak in a tyre.
In this case, what you're having to do is pressurise the aircraft, use a barometer, essentially, to monitor the pressure inside and look for leaks that way.
But there's no indication any air is escaping through the back door.
In this case they felt that it was alright and they completed the test.
The entire jet seems to be in good working order.
After performing a series of additional routine maintenance procedures, the engineers signed off on their technical log.
Investigators are faced with a dead end.
An explosive decompression could have explained the tragic events of Flight 522.
If the oxygen had been suddenly sucked out of the jet everyone on board could have been overcome.
But not only did engineers check the problem, when the F-16s approached the plane near Athens no damage was seen.
There was no indication that the fuselage was punctured.
ANDREAS: Mayday.
Investigators are still struggling to solve the mystery.
What had overcome the passengers and crew of Helios Flight 522? And why was one flight attendant apparently unaffected? The discovery of one small switch holds the key to the entire crash.
The crash of Helios Flight 522 is one of the most mysterious air disasters ever.
AIR TRAFFIC CONTROL: Helios 522, do you read? Over? All investigators know for sure is that shortly after take-off the crew stopped communicating with air traffic controllers.
Helios 522, over.
Mayday.
Then, after two and a half hours in the air, one of the plane's flight attendants was seen at the controls.
Eventually the plane ran out of fuel and crashed, killing 121 people.
But investigators are stumped.
They still don't know what had happened to the plane's captain or the rest of the crew.
Tell me about what happened the day of the flight.
They concentrate on the conversation between the pilot and the Helios engineer shortly after take-off.
As the plane passed through 3,700m, an alarm sounded in the cockpit.
Operations, this is Flight 522.
Over.
Flight 522.
What can I do for you? We have a take-off config warning on.
Pardon? Our take-off config warning is on.
Usually the take-off config warning is only triggered on the runway, but wreckage recovered at the crash site reveals no problems with the plane's flaps, landing gear or anything else that could trigger the alarm.
So why had it sounded? Chief Investigator Akrivos Tsolakis focuses on a small control panel found in the wreckage of the ravaged jet.
Are you sure this is the way it was found? It hasn't been moved at all? We were lucky finding this panel which had the switch on the manual position.
It was a major one.
The P5 pressurisation panel ensures that passengers have enough air to breathe, even at high altitudes.
Normally, pressurisation takes place automatically - as the jet climbs, its engines force air into the plane as they power it through the sky.
But when the pressurisation switch is set to 'manual' both the captain and copilot are responsible for maintaining the cabin atmosphere, using a controller.
So, explain again how you tested the pressure.
I went into the cockpit.
I turned the pressurisation switch to 'manual'.
Tsolakis learns that during the early-morning maintenance check on Helios 522 ground engineers had turned the P5 switch to manual.
That allowed them to use the on-board generators to test the pressure seals on the plane's rear door, without starting the engines.
When the test was over, they didn't turn the switch back to automatic.
FAITHON: The procedure of pressurising the aircraft has to do with setting the pressurisation system from auto to manual.
They were supposed to return the selector to the auto position.
Several hours later, when the flight crew entered the cockpit, the pressurisation switch was still set to manual.
PILOT: It's bright today.
Are you almost through? Pardon? But neither the pilot nor copilot saw it.
As a result, after take-off the cabin would not pressurise automatically.
And the higher Flight 522 climbed, the thinner the atmosphere became.
Not turning the switch back to automatic was a deadly hidden danger.
Are you sure this is the way it was found? It hasn't been moved at all? Tsolakis believes this panel could be the key to the disaster.
Leaving one switch on manual could have led to all the other problems the plane faced.
To prove he's right he takes an unusual step.
Four months after the disaster, he takes an Olympic Airlines 737 on the same route flown by the Helios jet.
If he's right about what caused the crash this plane should react exactly like the doomed airliner did.
Are we ready to go? When there is a complicated accident like this, I think re-enactments should be performed.
Of course, it's expensive to have a jetliner flying for three or four hours.
But it is worth it if you have to come with some results which are benefit to the overall investigation.
Make sure the P5 is set to manual.
Ah, it's hard to see.
In the cockpit Tsolakis has the crew turn the pressurisation switch to manual.
A green light indicates it's no longer on automatic.
But in the bright glare of an early-morning departure the light is hard to see.
As the re-enactment flight climbs, oxygen is thinning quickly in the aircraft.
The same thing happened on the Helios flight, triggering an alarm.
ALARM BEEPS What is it? The take-off config warning? FAITHON: The alarm sounded and that alarm was misinterpreted.
Most of flight crew, they would never face an alarm with no pressurisation in all their flight career, because it's a rare event.
Tsolakis confirms that the alarm went off because of the dangerously low air pressure in the aircraft.
But he also discovers that the sound itself is identical to the take-off config warning.
We have a take-off config warning on.
But even if the flight crew did misinterpret the first alarm, they still had another chance to determine what the real problem was.
At almost 5,000m, the plane's Master Caution light flashed on and stayed on for almost a minute.
We now have a Master Caution.
But, once again, the pilots misinterpreted the cause of the alarm.
The Master Caution light can indicate that the plane's systems are overheating but it can also tell pilots the oxygen masks are down.
In this case it was doing both at the same time.
But since the crew didn't think they were having pressurisation problems, they focused on the plane's cooling systems.
FAITHON: The alarm about the non-cooling was a side effect of non-pressurisation.
Actually it was not really that there was a high temperature inside the avionics bay but it was the sensors that were supposed to measure the temperature and the pressure in that area sensed that something was wrong.
On the re-creation flight, investigators monitor instruments recording the same events occurring on board their aircraft.
At the same time, they also begin to feel the effects of the lack of oxygen.
BILL: The first feelings you'd start to have were your ears would pop and start feeling pressure in your sinuses.
As you climb higher, you begin to feel almost giddy.
It's almost like having a couple of drinks of alcohol.
The dwindling oxygen levels could also help explain some of the crew's bizarre behaviour.
When the ground engineer asked about pressurisation Can you confirm that the pressurisation panel is set to auto? .
.
Captain Merten ignores the question and responds with one of his own.
Where are my equipment-cooling circuit-breakers? You really don't notice it at first.
It's amazing how subtle it can be in the early phases.
They'd start feeling dizzy, they begin to lose the ability to think coherently.
In a way, it traps you into the situation.
You can't react to anything.
Eventually, you're gonna lose consciousness.
Tsolakis believes that the captain may have been checking on the circuit-breakers behind his seat when he and the copilot finally ran out of air.
And unlike in the cabin, the oxygen masks in the cockpit do not automatically deploy if the atmosphere begins to thin.
MAN ON RADIO: Helios 522, can you hear me? On the other side of the locked cockpit door no-one in the cabin would have known that the plane was now flying itself.
Nor would they have realised that a limitation of the passenger oxygen system had sealed the fate of everyone in the cabin.
Passenger masks are supplied by a chemical generator above their seats.
But the generators only produce enough oxygen to last about 12 minutes.
Well, the problem with the passenger masks is For one thing, they're not designed to keep you oxygenated at a high altitude.
What they're designed to do is give you enough oxygen so that you can survive until the pilots get the aeroplane down to a low altitude.
In almost every event where we've had a decompression that's been perfectly adequate.
For those who did put their masks on they would have remained conscious for several minutes until their oxygen ran out.
Then they too would have passed out.
Once you get up to 34,000 feet you're talking useful consciousness of 30 to 60 seconds.
Most of the people, once the hypoxia begins to cause them to lose consciousness they're just gonna go to sleep.
Without a flight crew Helios 522 would have continued to Athens on autopilot.
When the crew didn't take control the autopilot would have put the jet in a holding pattern as it flew over the airport.
Exactly the same thing will happen on the reconstruction flight if cabin pressure isn't restored.
Tsolakis asks the copilot to reset the P5 panel to auto before the jet continues to climb to its cruising altitude of just over 10,000 metres.
Then, as it approaches Athens, Tsolakis also has an F-16 shadow the jet performing the re-creation.
He wants to confirm that it was Andreas Prodromou at the controls of Flight 522 when it went down.
MAN: We dressed one of our guys with the uniform of the steward.
He came in, he sat on the captain's chair.
And the F-16 was looking at him.
He was confirming it was exactly what he saw on the accident plane.
The reconstruction also answers another question about the tragic fate of Helios Flight 522.
The cockpit voice recorder picked up several strange noises.
They're heard just before Prodromou enters the cockpit.
Tsolakis confirms that these sounds were made by Prodromou using the electronic keypad to unlock the cockpit door.
We confirmed all those items during the enactment flight.
It was very, very useful.
It filled a lot of gaps we had.
OK, take it down.
For chief investigator Tsolakis the re-enactment flight has been convincing.
There was no dramatic cabin failure.
Instead, a series of small mistakes and misunderstandings had led to the worst air disaster in Greek history.
15 months after the crash Greek authorities released the official report on Helios Airways Flight 522.
But mysteries remain.
What was happening in the cabin while the doomed aeroplane flew towards Athens? And why was Andreas Prodromou the only one conscious at the very end? The crash of Helios Flight 522 was the worst disaster in the history of Greek aviation.
Like many crashes, it was a fatal combination of mechanical problems and human error.
The final accident report details a tragic series of oversights and false assumptions made by the flight crew.
Problems that could have been easily prevented turned deadly for all 121 people on board.
Where are my equipment-cooling circuit-breakers? MAN ON RADIO: Behind the captain's seat.
Can you see them? THUMP But what the final report does not do is explain what happened in the cabin of the plane.
What actions did the flight attendants take and why was Andreas Prodromou still conscious after almost three hours? ANDREAS: Mayday, mayday.
Interviews with Helios safety instructors and crew members paint a tragic picture of what may have occurred.
MAN: Everyone, please put your mask on.
We're not sure what the trouble is but remain calm and please remain seated.
Prodromou was sitting at the back of the cabin.
When the oxygen masks fell, he would've waited for instructions from the cockpit.
The flight attendant sitting at the front of the plane would have done the same but none of them would've waited forever.
MAN: We made it an issue at Helios to emphasise that cabin crews should not entirely depend on their procedures but to think on their feet and to adapt to any impending situation.
In most depressurisations, the plane descends quickly but as minutes passed on the Helios flight, the plane continued to climb.
Unsure of what was going on, Prodromou would have tried to contact the flight crew Captain.
Captain Merten.
.
.
but he gets no response.
Can you give us an update, please, Captain Merten? With no word from the cockpit, he would've soon realised that this was not a typical depressurisation.
When there was no call-out from the cockpit and the aircraft didn't start an emergency descent, there was absolutely no protocol.
They would be winging it.
By now, Prodromou must have felt that something was terribly wrong.
But to find out what the problem was, he had to leave his seat.
PAUL: The oxygen available on a 737 is, of course, the drop-out oxygen.
10% of those masks are available for the crew in case of a depressurisation incident.
There are extra masks per every seat row.
Taking advantage of the extra passenger masks, he could have made his way to the front of the plane, a process cabin crew called 'monkey swinging'.
(Inhales) But if more than 12 minutes had passed, his girlfriend and the other flight attendant may have still been in their seats and, like the passengers, overcome by hypoxia.
But Prodromou was a scuba diver and a former soldier in the Cypriot Special Forces.
His training may have helped him to stay alert a little longer.
(Speaks Greek) TRANSLATION: Andreas was not a coward.
He was a brave person.
Fearless, brave and very calm.
But to survive after the passenger oxygen system stopped working, he needed another solution.
The 737 had four portable oxygen bottles.
Each one could last more than an hour.
All four bottles were found at the crash site.
Three of them appeared to have been used.
While the F-16 pilot saw Prodromou in the cockpit just before the crash, it may not have been the first time he had gone in.
As he did at the end of the flight, he could've used the security code to unlock the door earlier.
LAZAROS: The procedure would be to enter the flight deck via the cockpit door.
Initially to bang on the door and then, if no response is forthcoming, to enter the code and enter the flight deck.
During the accident investigation, DNA was discovered on an oxygen mask in the cockpit that matched the copilot's.
It's possible Prodromou used it to try and revive him.
You can still revitalise somebody for quite an extended period of time if you get to them before major brain damage has set in and that's somewhat a variable situation depending on the person, depending on how long they're exposed to a high altitude.
But if he was in the cockpit earlier, why did he leave? No-one will ever know.
BILL: He probably was a little bit disoriented, a little bit confused.
He's reacting a lot slower than he normally would.
What was his state of mind? What was his physical condition? We think that he knew what was really the problem but is that the real situation? It's a real question.
After three hours in the air, everyone who didn't have bottled oxygen would've been unconscious.
As it approached Athens, Flight 522 was now a ghost plane.
Most of the victims, they probably still had heartbeats when the aeroplane crashed but almost certainly were in an irreversible coma.
Hypoxia is no more painful than falling asleep but for Andreas Prodromou, the flight must've been a nightmare.
(Gasps) As the F-16s roared to meet the jet and with his oxygen running out, he must've known that he too was almost out of time yet to the very end, he didn't give up.
BEEPING Prodromou made one last attempt to save the plane.
When he returns to the cockpit, the young flight attendant who dreamed of becoming a pilot calls for help but no-one can hear him, probably because the radio was still tuned to Larnaca, the airport on Cyprus where the flight had taken off.
Fighting hypoxia and struggling to control an aeroplane larger than any he had ever flown, Prodromou was in an impossible situation.
Even if he could've landed the plane, it was now too late.
Flight 522 was out of time and fuel.
There are pictures of Andreas in Cyprus in the cemetery where he and his girlfriend Haris are buried side by side.
(Kostantinos speaks Greek) TRANSLATION: As his father, my son is in front of me.
Wherever I go, he is always there.
(Speaks Greek) TRANSLATION: He left a very big gap.
(Speaks Greek) TRANSLATION: We will never get over it.
There are pictures in Greece too.
On the hill north of Athens where Helios Flight 522 crashed, there are faded photographs of many of those who died.
Bleached by the brilliant Mediterranean sun, they gaze over the rugged ancient terrain, silent witnesses to one of the world's most bizarre and tragic airline disasters.
Supertext Captions by the Australian Caption Centre
522, do you read? Over.
There's no answer from the passenger plane, but there is someone at the controls.
More than 100 people are on board.
Everybody's mind was going to a hijack or 'terrorists'.
There is one person moving in the cockpit.
Repeat, there is What happened to the crew and passengers? 522, do you read? Over.
And who is flying the plane? Helios 522, do you read? Over.
Early morning, August 14, 2005.
The cabin crew of Helios Airways Flight 522 are preparing for their trip from the island of Cyprus to Athens, Greece.
Sure is a beautiful day.
Maybe I shouldn't have come in.
Andreas Prodromou is 25.
He isn't supposed to be working today but he's taken the flight to spend some time with his girlfriend, who also works for Helios.
It's the sort of day I'd like to be up flying.
Oh! You will, Andreas.
Prodromou is a flight attendant now, but he has bigger plans.
One day he wants to fly for Helios.
(Man speaks Greek) TRANSLATION: His dream was to become a professional pilot.
Personally, I wanted him to stay in the family business.
We often talked about this.
We've got company.
- Stay warm at the back.
- I will.
See you in Athens.
In the cockpit, the flight crew is occupied with the daily routine of preparing their jet for take-off.
It's bright today.
Captain Hans Merten is an East German, a contract pilot hired by Helios for the busy holiday season.
Are you almost through? Pardon? Areyoualmostdone? Nearly.
His copilot is from Cyprus.
Pampos Charalampous has been working exclusively for Helios for the last five years.
Before beginning any flight, crews are required to perform dozens of checks on various pieces of on-board equipment.
It's a routine, but necessary, procedure.
Doors closed.
Sorry, could you store trays? Put your seatbelt on.
Helios is a charter airline with low-cost fares to Greece.
It's a summer weekend and the plane is filled with families.
In all, there are 115 passengers on the morning flight.
If you need any more help let me know.
We're just about to take off.
They are low-fare, no frills.
They don't even serve you refreshments during small sorts of flights.
But they offer another possibility for the budget-minded traveller.
Paris Dimitriou and Maria Rikkou are travelling to the Greek island of Paros.
They've just got engaged.
Ah, they booked they booked this holiday a month, or more than a month ago.
It was like a honeymoon for them.
CAPTAIN: Flight attendants, please take your seats.
Prepare for take-off.
See you later.
Just a few minutes after 9:00 in the morning Helios Airways Flight 522 lifts off into the bright sunshine.
Area Control, this is Helios 522.
Request cruising at 3-4-0.
AIR TRAFFIC CONTROL: Helios 522, you are cleared to climb to 340.
Have a good day.
Set 340.
Minutes into the flight, the plane is still climbing towards its cruising altitude.
Suddenly an alarm blares in the cockpit.
- LOUD BEEPING - What is it? BEEPING CONTINUES The take-off config warning? The flight crew is confused.
The take-off configuration alarm normally only sounds on the ground.
It tells pilots their jet isn't ready for take-off.
The crew doesn't know why it's sounding now.
Uncertain what the problem is, the captain radios the Helios Operations Centre at Larnaca Airport, back in Cyprus.
Operations, this is Flight 522, over.
Flight 522, what can I do for you? We have a take-off config warning on.
Pardon? Our take-off config warning is on.
I'm sure it's nothing.
I'll let you know when we level off.
With the first alarm still beeping in the cockpit, things become even more confusing.
Their Master Caution alarm goes off.
It could indicate that some systems on board are overheating.
We now have a Master Caution.
I'll get you an engineer.
522, just a minute.
I find him very hard to understand.
His accent is quite thick.
Flight 522, what can I do for you? ALARM BEEPS The ventilation cooling fan lights are off.
Sorry, could you repeat? While the pilots and ground engineers try to troubleshoot the two alarms, most passengers have no idea there's a problem until (All gasp) Everyone, stay calm.
Please remain seated.
Everyone, please put the oxygen masks on completely over your mouth and nose.
MAN: The protocol was immediately to secure yourself, grab an oxygen mask, stay in your seat.
If you can help passengers without getting up you could help them and you should help them, but you would not risk the safety of any cabin crew member to go and help a passenger which is five or six rows further up.
MAN: Their procedure would be to grab their mask, don it, and wait for the aircraft to level off or commence with a descent.
No-one in the cabin knows what the problem is.
They're waiting for information from the cockpit.
The pilots are unaware that the oxygen masks in the cabin have dropped and they still don't know why their take-off configuration warning is on or why their systems are overheating.
Both of my equipment-cooling lights are off.
This is normal.
Can you please confirm your problem? But the engineer on the ground is struggling to get a clear picture of what's happening in the air.
They are not switched off.
Can you confirm that the pressurisation panel is set to 'auto'? Where are my equipment-cooling circuit-breakers? Behind the captain's seat.
Can you see them? What's going on? There's something wrong with the electrics on 522.
LAZAROS: I had something to pick up from operations, so I was there.
I figured, "Oh, not again.
One of our problems.
" SoI left.
Well, good luck.
The problem doesn't seem serious.
But as the plane continues to climb passengers still haven't received any information from the cockpit.
Helios 522, can you see the circuit-breakers? And now the engineer on the ground loses contact with the aircraft.
Helios 522.
Can you hear me? It's less than 30 minutes after take-off and Flight 522 is still on course.
The plane is high above the Mediterranean Sea and headed straight towards Athens.
August 14, 2005.
A Helios Airways 737 with 121 people on board is circling in the sky near Athens.
Helios 522.
Can you hear me? Shortly after leaving the island of Cyprus two different alarms had been triggered on the plane.
The flight crew was trying to solve the problem with the help of ground engineers.
But now radio contact with the plane has been lost.
Air Traffic Control can't get any response from the captain or copilot.
The flight to Greece normally takes an hour and a half.
But the passenger jet has been in the air for over two hours, circling in a holding pattern.
MAN: We heard that there was an aeroplane which was flying to the Greek territory and had no communication.
Everybody's mind was going to a hijack or to terrorists.
More than 3 million people live in Athens.
A plane slamming into the city could cause an incredible loss of life.
FAITHON: This is a runaway aircraft.
It's a possible hijacking or it's a possible terrorist act, so let's involve the military.
The Greek Air Force scrambles two of its most sophisticated fighter jets to investigate the Helios plane.
MAN: Helios 522, do you read? Over.
But the pilots aren't getting any response.
One of the jets flies closer to the cockpit.
Someone is in the copilot's seat, slumped over the controls.
But there's no sign of the captain at all.
The fighter pilot radios Air Traffic Control in Athens.
Athinai ACC, there is one figure in the cockpit of Helios 522.
He appears non-responsive.
Athinai ACC, checking the cabin.
He can see passengers in their seats but none of them reacts to the presence of the jet.
Then the pilot sees someone moving in the cockpit.
Athinai Control, there is one person moving in the cockpit of Helios 522.
Repeat, there is one person inside the cockpit.
Helios 522, do you read? Over.
Helios 522, over.
Flight HCY 522, this is Athinai Radar Control.
The F-16s continue shadowing the jet but there's no response at all from the cockpit.
One of them was actually in the shooting position, behind the 737.
The other one was nearby the cockpit, and he was trying to communicate visually with the person in the cockpit.
Suddenly the 737 turns left and begins to quickly descend.
Athinai ACC, Helios 522 turning sharply.
Following down.
For more than 10,000m the plane drops towards the ground.
There is no structural failure.
There is no fire.
There is no problem, obvious problem, from the external view, with the plane.
AIR TRAFFIC CONTROL: Helios 522, over.
Do you read? Helios 522, do you read? Over.
ALARMS BEEP Then, 2,100m above the ground, the person in the captain's seat acknowledges the fighter jet for the very first time.
But no words are exchanged.
Neither the fighter pilot nor local air traffic control can make radio contact with the jet.
Just after 12:00, almost three hours after it took off from the island of Cyprus, Helios Flight 522 slams into the ground.
Athinai ACC, Helios 522 is down.
Repeat, Helios 522 is down on Grammatiko Hill.
Over.
Fire and rescue workers rush to the crash site.
There are no survivors.
Flight attendant Lazaros Temetzian is stunned by what he hears at the company's Operations Centre.
It was the most chaotic scene I've ever seen.
When I went back our Operations Controller said that he'd lost the aircraft.
And his eyes He was starting to cry.
Helios is a small company with just three jets.
Members of the cabin crew have been working together for years.
For Paul Symeonides, news of the crash is particularly terrifying.
He's a flight attendant for the airline, and so is his fiancee.
I think that must've been the worst 30 minutes of my life, following that first image, because Victoria was flying that morning to Glasgow.
I had everyone and his brother, every person we knew was calling me up to find out if I'm alive, if Victoria's alive, what happened, why it happened.
WOMAN: At first we said, "It takes one hour and half to go to Greece, "so probably is not that plane.
" And took about two or three hours later to know that Paris and Maria was on the plane that crashed.
Andreas Prodromou's father didn't know his son had been called to fill in on Flight 522.
(Man speaks Greek) TRANSLATION: I was told that Helios aircraft was lost by radar and air controllers couldn't contact it.
I got worried.
I called Andreas's phone - he always had it on - and, unfortunately, he wouldn't answer.
After that phone call, I felt as if the ground was pulled out from under my feet.
It's the worst air crash in the history of Greece.
Most of the 121 victims are from Cyprus.
The small island nation declares three days of mourning following the crash.
It's an eerie disaster.
For over an hour air traffic controllers watched the passenger jet fly in radio silence closer and closer to Athens, with no idea what was happening inside the jet.
Now, piece by piece, investigators are trying to find out.
MAN: So we climbed over the hill and there we were, you know, facing this situation, which was beyond anyany description.
I saw a great area in front of me which was burning.
It was black.
Burning.
People spread.
Pieces ofof the aeroplane.
TRANSLATION: It is a truly nightmarish sight.
I hope that I never experience it again.
It was terrible.
Just terrible.
August 14, 2005.
Athinai ACC, Helios 522 is down.
Investigators immediately start looking for the cause of the crash.
In the early days, their efforts take a frustrating turn.
They recover the box containing the cockpit voice recorder .
.
but the recorder itself has been thrown clear.
It was difficult for us, because we first found the case of the CVR very badly damaged.
And we could not find the you knowthe machine itself.
Investigators need to know what happened to the pilots.
Without the cockpit voice recorder, they have little to go on.
So keep looking.
Let's hope we can find it.
Bodies recovered from the wreckage are brought to the offices of Athens' Chief Coroner.
Autopsies add more mystery to the case.
Everyone on board the plane was alive at the time of the crash.
DR KONTSAFTIS: There were scenarios at the time that they had all died in midair.
But the truth .
.
they did not die from inhaling a toxic substance in the aeroplane or from an explosion.
These people died on impact.
(Speaks Greek) But if the passengers were alive the entire flight, why didn't the pilot of the fighter jet see any activity inside the cabin? And who was at the controls as the jet circled over Athens? When investigators find tissue samples in the remains of the cockpit, they make a stunning discovery.
The person at the controls of the plane when it crashed was Flight Attendant Andreas Prodromou, a last-minute addition to the cabin crew.
But why was he in the cockpit? Was he trying to save the plane? Or did he deliberately fly it into the ground? Several days after finding the outer case of the cockpit voice recorder, investigators find the recording itself.
When Chief Investigator Tsolakis listens to the final moments of the flight, it answers a vital question.
(Faintly) Mayday.
Mayday.
This was no terrorist act.
Flight 522 Prodromou was calling for help.
Mayday.
Mayday.
Tsolakis hears five separate 'maydays' on the tape, even though none of them were heard by the air traffic controllers.
From the first moment that they saw someone in the cockpit, believe me, I was certain it was Andreas.
He wasn't a coward.
He knew something about planes and he had the capacity to do something.
In fact, Prodromou had his commercial pilot's licence.
It was the first step towards his goal of becoming a captain for Helios.
It's the sort of day I'd like to be up flying.
Oh, you will, Andreas.
But all of his training wouldn't have helped save the jet.
When he was seen at the controls, Flight 522 had been in the air for almost three hours.
And the reason the Helios plane seemed to veer away from the F-16s following it was because its left engine was out of fuel.
No matter what caused the alarms to sound, the ultimate reason for the crash was simple.
The FDR and CVR gave us absolute proof that the plane ran out of fuel.
And this was the cause of the crash.
Scheduled as a 90-minute flight, the plane didn't have enough fuel to stay in the air for over three hours.
But why had the plane flown so much longer than it was supposed to? Tsolakis now knows who was in the cockpit of the plane and why it crashed.
But to fully understand the mystery he needs more information.
ANDREAS: Mayday.
His investigators uncover a suspicious history of maintenance issues with the Helios jet - issues that could help explain what happened on Flight 522.
Less than a year before the crash, the same aircraft had suffered a rapid decompression.
LOUD BANG (People scream) Lazaros Temetzian worked on that flight.
LAZAROS: I was in the back of the aircraft at the time.
There was a loud metallic bang, a clanging sound, and the oxygen masks dropped in the cabin.
Every step I was taking was difficult.
It was hard to move, hard to breathe.
In fact, I was I was starting to pant.
I was panting for air.
As the plane began an immediate descent to 3,300m, all Temetzian could do was remain strapped in and wait.
Once the plane reached a safe altitude, Temetzian inspected the rear door and was shocked by what he found.
I had noticed that the aft service door was not fully locked.
The hinges on the top and the bottom of the door were kind of displaced.
I could pass my hands right through.
There were no injuries and the plane made an emergency landing and the door was inspected.
But this wasn't the only problem crews had with this plane.
We would record faults in the cabin logbook constantly.
And nothing would be done to rectify even these small little problems in the cabin.
Engineers would take months to rectify even the slightest problem in the cabin.
There were more recent problems as well.
A Helios ground engineer tells Tsolakis that on the very day of Flight 522 the 737 had another problem with its back door.
When we checked the flight log for the trip we saw that we'd have to do some unscheduled maintenance.
The plane had arrived in Cyprus just after midnight on August 14.
The cabin crew had heard loud banging noises and saw ice on the rear service door during the flight.
It was scheduled to take off again, just hours later.
Soon after it landed, engineers began checking the problem.
To make sure there's nothing wrong with the seal on the door, the engineers run a pressurisation test.
During normal flight, a plane's engines force air into the cabin.
To ensure oxygen circulates during the trip, small valves in the rear allow some of it to leak out.
MAN: A pressurised aeroplane, essentially, is sort of like a pressurised can.
Well, we pressurise the aeroplane so that the people inside can survive the environment that the aeroplane likes to operate in.
Switching digital pressure control unit from auto to manual.
Without the jet's engines running, the engineer uses the plane's auxiliary power unit to force air into the aircraft and the cabin is pressurised for several minutes.
BILL: It's like looking for a leak in a tyre.
In this case, what you're having to do is pressurise the aircraft, use a barometer, essentially, to monitor the pressure inside and look for leaks that way.
But there's no indication any air is escaping through the back door.
In this case they felt that it was alright and they completed the test.
The entire jet seems to be in good working order.
After performing a series of additional routine maintenance procedures, the engineers signed off on their technical log.
Investigators are faced with a dead end.
An explosive decompression could have explained the tragic events of Flight 522.
If the oxygen had been suddenly sucked out of the jet everyone on board could have been overcome.
But not only did engineers check the problem, when the F-16s approached the plane near Athens no damage was seen.
There was no indication that the fuselage was punctured.
ANDREAS: Mayday.
Investigators are still struggling to solve the mystery.
What had overcome the passengers and crew of Helios Flight 522? And why was one flight attendant apparently unaffected? The discovery of one small switch holds the key to the entire crash.
The crash of Helios Flight 522 is one of the most mysterious air disasters ever.
AIR TRAFFIC CONTROL: Helios 522, do you read? Over? All investigators know for sure is that shortly after take-off the crew stopped communicating with air traffic controllers.
Helios 522, over.
Mayday.
Then, after two and a half hours in the air, one of the plane's flight attendants was seen at the controls.
Eventually the plane ran out of fuel and crashed, killing 121 people.
But investigators are stumped.
They still don't know what had happened to the plane's captain or the rest of the crew.
Tell me about what happened the day of the flight.
They concentrate on the conversation between the pilot and the Helios engineer shortly after take-off.
As the plane passed through 3,700m, an alarm sounded in the cockpit.
Operations, this is Flight 522.
Over.
Flight 522.
What can I do for you? We have a take-off config warning on.
Pardon? Our take-off config warning is on.
Usually the take-off config warning is only triggered on the runway, but wreckage recovered at the crash site reveals no problems with the plane's flaps, landing gear or anything else that could trigger the alarm.
So why had it sounded? Chief Investigator Akrivos Tsolakis focuses on a small control panel found in the wreckage of the ravaged jet.
Are you sure this is the way it was found? It hasn't been moved at all? We were lucky finding this panel which had the switch on the manual position.
It was a major one.
The P5 pressurisation panel ensures that passengers have enough air to breathe, even at high altitudes.
Normally, pressurisation takes place automatically - as the jet climbs, its engines force air into the plane as they power it through the sky.
But when the pressurisation switch is set to 'manual' both the captain and copilot are responsible for maintaining the cabin atmosphere, using a controller.
So, explain again how you tested the pressure.
I went into the cockpit.
I turned the pressurisation switch to 'manual'.
Tsolakis learns that during the early-morning maintenance check on Helios 522 ground engineers had turned the P5 switch to manual.
That allowed them to use the on-board generators to test the pressure seals on the plane's rear door, without starting the engines.
When the test was over, they didn't turn the switch back to automatic.
FAITHON: The procedure of pressurising the aircraft has to do with setting the pressurisation system from auto to manual.
They were supposed to return the selector to the auto position.
Several hours later, when the flight crew entered the cockpit, the pressurisation switch was still set to manual.
PILOT: It's bright today.
Are you almost through? Pardon? But neither the pilot nor copilot saw it.
As a result, after take-off the cabin would not pressurise automatically.
And the higher Flight 522 climbed, the thinner the atmosphere became.
Not turning the switch back to automatic was a deadly hidden danger.
Are you sure this is the way it was found? It hasn't been moved at all? Tsolakis believes this panel could be the key to the disaster.
Leaving one switch on manual could have led to all the other problems the plane faced.
To prove he's right he takes an unusual step.
Four months after the disaster, he takes an Olympic Airlines 737 on the same route flown by the Helios jet.
If he's right about what caused the crash this plane should react exactly like the doomed airliner did.
Are we ready to go? When there is a complicated accident like this, I think re-enactments should be performed.
Of course, it's expensive to have a jetliner flying for three or four hours.
But it is worth it if you have to come with some results which are benefit to the overall investigation.
Make sure the P5 is set to manual.
Ah, it's hard to see.
In the cockpit Tsolakis has the crew turn the pressurisation switch to manual.
A green light indicates it's no longer on automatic.
But in the bright glare of an early-morning departure the light is hard to see.
As the re-enactment flight climbs, oxygen is thinning quickly in the aircraft.
The same thing happened on the Helios flight, triggering an alarm.
ALARM BEEPS What is it? The take-off config warning? FAITHON: The alarm sounded and that alarm was misinterpreted.
Most of flight crew, they would never face an alarm with no pressurisation in all their flight career, because it's a rare event.
Tsolakis confirms that the alarm went off because of the dangerously low air pressure in the aircraft.
But he also discovers that the sound itself is identical to the take-off config warning.
We have a take-off config warning on.
But even if the flight crew did misinterpret the first alarm, they still had another chance to determine what the real problem was.
At almost 5,000m, the plane's Master Caution light flashed on and stayed on for almost a minute.
We now have a Master Caution.
But, once again, the pilots misinterpreted the cause of the alarm.
The Master Caution light can indicate that the plane's systems are overheating but it can also tell pilots the oxygen masks are down.
In this case it was doing both at the same time.
But since the crew didn't think they were having pressurisation problems, they focused on the plane's cooling systems.
FAITHON: The alarm about the non-cooling was a side effect of non-pressurisation.
Actually it was not really that there was a high temperature inside the avionics bay but it was the sensors that were supposed to measure the temperature and the pressure in that area sensed that something was wrong.
On the re-creation flight, investigators monitor instruments recording the same events occurring on board their aircraft.
At the same time, they also begin to feel the effects of the lack of oxygen.
BILL: The first feelings you'd start to have were your ears would pop and start feeling pressure in your sinuses.
As you climb higher, you begin to feel almost giddy.
It's almost like having a couple of drinks of alcohol.
The dwindling oxygen levels could also help explain some of the crew's bizarre behaviour.
When the ground engineer asked about pressurisation Can you confirm that the pressurisation panel is set to auto? .
.
Captain Merten ignores the question and responds with one of his own.
Where are my equipment-cooling circuit-breakers? You really don't notice it at first.
It's amazing how subtle it can be in the early phases.
They'd start feeling dizzy, they begin to lose the ability to think coherently.
In a way, it traps you into the situation.
You can't react to anything.
Eventually, you're gonna lose consciousness.
Tsolakis believes that the captain may have been checking on the circuit-breakers behind his seat when he and the copilot finally ran out of air.
And unlike in the cabin, the oxygen masks in the cockpit do not automatically deploy if the atmosphere begins to thin.
MAN ON RADIO: Helios 522, can you hear me? On the other side of the locked cockpit door no-one in the cabin would have known that the plane was now flying itself.
Nor would they have realised that a limitation of the passenger oxygen system had sealed the fate of everyone in the cabin.
Passenger masks are supplied by a chemical generator above their seats.
But the generators only produce enough oxygen to last about 12 minutes.
Well, the problem with the passenger masks is For one thing, they're not designed to keep you oxygenated at a high altitude.
What they're designed to do is give you enough oxygen so that you can survive until the pilots get the aeroplane down to a low altitude.
In almost every event where we've had a decompression that's been perfectly adequate.
For those who did put their masks on they would have remained conscious for several minutes until their oxygen ran out.
Then they too would have passed out.
Once you get up to 34,000 feet you're talking useful consciousness of 30 to 60 seconds.
Most of the people, once the hypoxia begins to cause them to lose consciousness they're just gonna go to sleep.
Without a flight crew Helios 522 would have continued to Athens on autopilot.
When the crew didn't take control the autopilot would have put the jet in a holding pattern as it flew over the airport.
Exactly the same thing will happen on the reconstruction flight if cabin pressure isn't restored.
Tsolakis asks the copilot to reset the P5 panel to auto before the jet continues to climb to its cruising altitude of just over 10,000 metres.
Then, as it approaches Athens, Tsolakis also has an F-16 shadow the jet performing the re-creation.
He wants to confirm that it was Andreas Prodromou at the controls of Flight 522 when it went down.
MAN: We dressed one of our guys with the uniform of the steward.
He came in, he sat on the captain's chair.
And the F-16 was looking at him.
He was confirming it was exactly what he saw on the accident plane.
The reconstruction also answers another question about the tragic fate of Helios Flight 522.
The cockpit voice recorder picked up several strange noises.
They're heard just before Prodromou enters the cockpit.
Tsolakis confirms that these sounds were made by Prodromou using the electronic keypad to unlock the cockpit door.
We confirmed all those items during the enactment flight.
It was very, very useful.
It filled a lot of gaps we had.
OK, take it down.
For chief investigator Tsolakis the re-enactment flight has been convincing.
There was no dramatic cabin failure.
Instead, a series of small mistakes and misunderstandings had led to the worst air disaster in Greek history.
15 months after the crash Greek authorities released the official report on Helios Airways Flight 522.
But mysteries remain.
What was happening in the cabin while the doomed aeroplane flew towards Athens? And why was Andreas Prodromou the only one conscious at the very end? The crash of Helios Flight 522 was the worst disaster in the history of Greek aviation.
Like many crashes, it was a fatal combination of mechanical problems and human error.
The final accident report details a tragic series of oversights and false assumptions made by the flight crew.
Problems that could have been easily prevented turned deadly for all 121 people on board.
Where are my equipment-cooling circuit-breakers? MAN ON RADIO: Behind the captain's seat.
Can you see them? THUMP But what the final report does not do is explain what happened in the cabin of the plane.
What actions did the flight attendants take and why was Andreas Prodromou still conscious after almost three hours? ANDREAS: Mayday, mayday.
Interviews with Helios safety instructors and crew members paint a tragic picture of what may have occurred.
MAN: Everyone, please put your mask on.
We're not sure what the trouble is but remain calm and please remain seated.
Prodromou was sitting at the back of the cabin.
When the oxygen masks fell, he would've waited for instructions from the cockpit.
The flight attendant sitting at the front of the plane would have done the same but none of them would've waited forever.
MAN: We made it an issue at Helios to emphasise that cabin crews should not entirely depend on their procedures but to think on their feet and to adapt to any impending situation.
In most depressurisations, the plane descends quickly but as minutes passed on the Helios flight, the plane continued to climb.
Unsure of what was going on, Prodromou would have tried to contact the flight crew Captain.
Captain Merten.
.
.
but he gets no response.
Can you give us an update, please, Captain Merten? With no word from the cockpit, he would've soon realised that this was not a typical depressurisation.
When there was no call-out from the cockpit and the aircraft didn't start an emergency descent, there was absolutely no protocol.
They would be winging it.
By now, Prodromou must have felt that something was terribly wrong.
But to find out what the problem was, he had to leave his seat.
PAUL: The oxygen available on a 737 is, of course, the drop-out oxygen.
10% of those masks are available for the crew in case of a depressurisation incident.
There are extra masks per every seat row.
Taking advantage of the extra passenger masks, he could have made his way to the front of the plane, a process cabin crew called 'monkey swinging'.
(Inhales) But if more than 12 minutes had passed, his girlfriend and the other flight attendant may have still been in their seats and, like the passengers, overcome by hypoxia.
But Prodromou was a scuba diver and a former soldier in the Cypriot Special Forces.
His training may have helped him to stay alert a little longer.
(Speaks Greek) TRANSLATION: Andreas was not a coward.
He was a brave person.
Fearless, brave and very calm.
But to survive after the passenger oxygen system stopped working, he needed another solution.
The 737 had four portable oxygen bottles.
Each one could last more than an hour.
All four bottles were found at the crash site.
Three of them appeared to have been used.
While the F-16 pilot saw Prodromou in the cockpit just before the crash, it may not have been the first time he had gone in.
As he did at the end of the flight, he could've used the security code to unlock the door earlier.
LAZAROS: The procedure would be to enter the flight deck via the cockpit door.
Initially to bang on the door and then, if no response is forthcoming, to enter the code and enter the flight deck.
During the accident investigation, DNA was discovered on an oxygen mask in the cockpit that matched the copilot's.
It's possible Prodromou used it to try and revive him.
You can still revitalise somebody for quite an extended period of time if you get to them before major brain damage has set in and that's somewhat a variable situation depending on the person, depending on how long they're exposed to a high altitude.
But if he was in the cockpit earlier, why did he leave? No-one will ever know.
BILL: He probably was a little bit disoriented, a little bit confused.
He's reacting a lot slower than he normally would.
What was his state of mind? What was his physical condition? We think that he knew what was really the problem but is that the real situation? It's a real question.
After three hours in the air, everyone who didn't have bottled oxygen would've been unconscious.
As it approached Athens, Flight 522 was now a ghost plane.
Most of the victims, they probably still had heartbeats when the aeroplane crashed but almost certainly were in an irreversible coma.
Hypoxia is no more painful than falling asleep but for Andreas Prodromou, the flight must've been a nightmare.
(Gasps) As the F-16s roared to meet the jet and with his oxygen running out, he must've known that he too was almost out of time yet to the very end, he didn't give up.
BEEPING Prodromou made one last attempt to save the plane.
When he returns to the cockpit, the young flight attendant who dreamed of becoming a pilot calls for help but no-one can hear him, probably because the radio was still tuned to Larnaca, the airport on Cyprus where the flight had taken off.
Fighting hypoxia and struggling to control an aeroplane larger than any he had ever flown, Prodromou was in an impossible situation.
Even if he could've landed the plane, it was now too late.
Flight 522 was out of time and fuel.
There are pictures of Andreas in Cyprus in the cemetery where he and his girlfriend Haris are buried side by side.
(Kostantinos speaks Greek) TRANSLATION: As his father, my son is in front of me.
Wherever I go, he is always there.
(Speaks Greek) TRANSLATION: He left a very big gap.
(Speaks Greek) TRANSLATION: We will never get over it.
There are pictures in Greece too.
On the hill north of Athens where Helios Flight 522 crashed, there are faded photographs of many of those who died.
Bleached by the brilliant Mediterranean sun, they gaze over the rugged ancient terrain, silent witnesses to one of the world's most bizarre and tragic airline disasters.
Supertext Captions by the Australian Caption Centre