It is one of the most bizarre flying stories of all time.
Situation
A Helios Airways Boeing 737 is circling the city of Athens for more than two hours in a holding pattern. There is no communications from the plane even after multiple attempts. The Greek air force sends two of its fighter jets to investigate the situation. One of them is in a shooting position behind the 737 while the other one is trying to visually assess the situation. The fighter pilot can see passengers on their seats but none of them are moving or reacting to the presence of a fighter jet. There is one person on the co-pilots seat, slumped over the controls and appears to be unconscious. The captain's seat is vacant.
Then the fighter pilot radios that there is one other person moving in the cockpit! But this person is not communicating with the fighter pilot. This person sits on the captain's seat and after few minutes, the plane makes a sudden left turn and starts to descent to a lower altitude.
Sounds like a movie?
This true story is as suspenseful as a good thriller movie. I strongly suggest that you watch this documentary of Air Crash Investigation. It is highly dramatized and made nearly like a movie itself.
Air Crash Investigation - Ghost Plane - Helios Flight 522
But if you choose to read, then continue.
The story of Helios flight 522 begins with Andreas Prodromou, a flight attendant who is preparing the cabin for the early morning flight from Cyprus to Athens, Greece. The date is 14th August 2005. Andreas is actually not supposed to be working today, but he volunteered for this flight because he wants to spend some time with his girlfriend who is also a flight attendant for Helios. Andreas has bigger plans, he wants to become a professional pilot one day. He also has a commercial pilot license, but he is not yet qualified to fly big planes such as a Boeing 737. He had taken the job as a steward at Helios Airways after failing to find work as a pilot, despite strong pressure from his family not to take a position for which he was over-qualified.
Helios is a small low cost airline with just 3 planes. The crew of the entire airline has been working together for a few years and know each other personally. 115 passengers boarded the plane and got seated for the flight.
In the cockpit, Hans-Jürgen Merten, a 58-year-old German contract pilot hired by Helios for the holiday season, was the captain. He had been flying for 35 years and had accrued 16,900 flight hours. Pampos Charalambous, 51, a Cypriot who flew exclusively for Helios, served as the first officer. He had accrued 7,549 flight hours throughout his career. They were preparing the plane for take off. It was a routine procedure to check all important systems before the flight.
Louisa Vouteri, a 32-year-old Greek national living in Cyprus, replaced a sick colleague as the chief purser (chief flight attendant). The purser oversees the flight attendants by making sure airline passengers are safe and comfortable.
At 9:07AM, Helios 522 takes off from Larnaca International Airport. As the flight reached 12,000 ft, a warning alarm starts beeping in the cockpit. The pilots identifies the alarm as 'take off configuration warning'. But they are confused because the take off configuration warning only sounds when the plane is on the ground, and it means that the plane is not ready for the flight. It is never supposed to happen when the plane is in the air.
Unsure why the alarm is beeping, the captain contacts the Helios operation center for support from the ground engineers. He radios that his "take-off configuration warning is on" and "cooling equipment normal and alternate off line".
After few minutes, their equipment cooling warning lights came on to indicate low airflow through the cooling fans, accompanied by their master caution alarm. He conveys this to the ground engineer. He then repeatedly stated that the "cooling ventilation fan lights were off".
The previous day, when the aircraft arrived from London Heathrow, the previous flight crew had reported a frozen door seal and abnormal noises coming from the right aft service door. They requested a full inspection of the door. The inspection was carried out by a ground engineer who then performed a pressurization leak check.
In the cabin, passengers did not know about the situation in the cockpit until the passenger oxygen masks came down. The cabin crew requested everyone to remain in their seats and put on the oxygen masks. The flight attendants also put on their own oxygen masks and waited for further information from the cockpit.
The pilots, unaware the oxygen masks were coming down in the cabin, continued their troubleshooting with the ground engineers. The engineer (the one who had conducted the pressurization leak check) asked "Can you confirm that the pressurization panel is set to AUTO?" The captain, disregarded the question and instead asked in reply, "Where are my equipment cooling circuit breakers?". The ground engineers reply that it is behind the captain's seat. They now lose radio contact with the plane.
The plane is still climbing and on course to Athens. The passengers have not received any information from the cockpit.
After two hours, the Helios 522 is circling the city of Athens. Nineteen attempts were made to contact the plane but there was no response. The air traffic controllers in Athens got worried about the possibility of a terrorist attack. A plane crash in the city can cause large loss of life. They informed the military about the runaway aircraft. The Greek air-force quickly sends two F-16 fighter jets to investigate the situation.
The F-16 pilots reported seeing the pilot's seat empty and the co-pilot slumped over the controls, possibly unconscious. They observed no movement in the cabin. They also reported about the oxygen masks in the cabin. The F-16s shadowed the jet and tried to visually establish contact with the plane.
Then, the F-16 pilots saw a person moving in the cockpit. This person sits on the captain's seat and takes over the controls. For the first time, this person acknowledges the fighter pilots by waving hands.
The plane suddenly turns left and starts descending. The F-16s follows the plane. It first levels off at 10,000 feet and then again descends to 2,500 feet. Three hours after the Helios 522 took off from Cyprus, the plane slammed into the ground.
The F-16 pilot radios that Helios 522 has crashed into barren hills near Grammatiko.
Firefighters and rescue teams rushes to the location, but there are no survivors.
It is the worst plane crash in the history of Greece.
Most of the passengers were from Cyprus. The small island nation of Cyprus declares three days of mourning.
There were theories that all the passengers died in the air. But autopsies conducted on the bodies, revealed that they died on impact. But if the passengers were alive then why didn't the F-16s see any movement?
DNA analysis on samples from the cockpit revealed that Andreas Prodromou was inside the cockpit. This raised many questions about whether the flight attendant was trying to save the plane or trying to deliberately crash the plane.
The plane's black box revealed that the last left turn which the F-16s saw happened because the left engine switched off due to lack of fuel. The plane had ultimately crashed due to the lack of fuel.
The investigator finds this panel from the wreckage. The investigators observes that the pressurization knob was set to manual. which means that the plane's air pressure needs to be maintained manually by the pilots. It is usually always set to auto, so that the plane automatically adjusts the cabin pressure. Without this, the plane's air pressure will decrease as the plane climbs to higher altitude.
It was soon discovered that the engineer who conducted the pressurization test on the day before the crash forgot to turn this knob back to auto after concluding the test. After the aircraft returned to service, the flight crew overlooked the pressurization system state on three separate occasions: during the pre-flight procedure, the after-start check, and the after take-off check. During these checks, no one in the flight crew noticed the incorrect setting since no one typically changes the pressurization knobs.
As the aircraft climbed, the pressure inside the cabin gradually decreased. As it passed through an altitude of 12,000 feet (3,670 m), the cabin altitude warning horn sounded. The warning should have prompted the crew to stop climbing, but it was misidentified by the crew as a take-off configuration warning, which signals that the aircraft is not ready for take-off, and can only sound on the ground. They misidentified it because most pilots will never ever hear cabin altitude warning in their entire careers, and because it also sounds similar to the take-off configuration warning. Boeing was blamed for making two similar sounding warning alarms.
When the cockpit voice recorder (a part of black box) was played, the investigators heard 5 different Mayday calls from Andreas Prodromou. He sounded exhausted and tired. He was trying to save the plane. But the calls were not heard by the air traffic controller because the radio was still tuned to the frequency set for Cyprus.
The crew must have waited a few minutes for further information from the captain after the oxygen masks dropped.
But they may not have waited forever. After some time, they may have tried to contact the cockpit using the intercom. Andreas was seated at the back of the cabin.
The passengers oxygen mask only contains enough oxygen for 12 minutes after which everyone on board became unconscious due to hypoxia (oxygen deprivation). No alarm shows the pilots that the oxygen masks have dropped in the cabin, and pilots mask needs to be manually used. The pilots didn't wear their own oxygen masks because they didn't consider this as a problem.
At that altitude, anyone without the oxygen mask can fall unconscious within 20 to 60 seconds. This is why flight attendants always advise in their flight emergency procedures to put your oxygen mask on first before helping children or other passengers.
Oxygen deprivation can also decrease cognitive thinking ability which may be the reason why the pilots were acting slow. The airplane continued its journey on autopilot to Athens where it entered the holding pattern above the city.
The standard procedure when the oxygen masks come down is to descend to a lower altitude where the passengers can breath normally.
When several calls to the cabin was unanswered, and when the plane continued to climb, Andreas must have tried to come forward using the additional passenger oxygen masks. The passengers and crew must have gone unconscious after the 12 minutes. Hypoxia is no more painful than falling asleep. Andreas was a Scuba diver and had served in the special forces; his training may have helped him stay conscious longer than the others on the plane. A Boeing 737 has four portable oxygen masks, and he must have used one of those to stay conscious till the end of the flight.
After 9/11 incident, all passenger planes have nearly unbreakable cabin door, so flight attendants cannot directly access the pilots. He banged the cockpit door several times, and when the pilots didn't respond he typed the security code and entered the cockpit. The sound of the door-bangs and the clicking of the number pad are recorded in the cockpit voice recorder (a part of black box).
DNA from a pilot was also found on one of the portable oxygen masks. So Andreas may have tried to revive the pilots using the portable oxygen masks.
Although he held a UK Commercial Pilot License he was not qualified to fly the Boeing 737. Crash investigators concluded that Prodromou's experience was insufficient for him to gain control of the aircraft under the circumstances.
Even if he could land the 737, a plane bigger than any plane he had ever flown, it was too late: he did not have time to save the stricken aircraft. Almost as soon as the F-16 pilots saw him enter the cockpit, the left engine flamed out due to fuel exhaustion, and the plane left the holding pattern and started to descend.
As it approached Athens, it was a ghost plane. By then, the passengers and crew would have been in an irreversible coma.
Ten minutes after the loss of power from the left engine, the right engine also flamed out, and just before 12:04 the aircraft crashed into the hills near Grammatiko.
Andreas may have also entered the cockpit earlier. But he was in an impossible situation. Just imagine being in his situation. Imagine standing alone in the cabin while everyone he works with and all passengers are dying. Even his girlfriend was unconscious and dying. He also knows that he is also going to die when his oxygen runs out. His psychological situation is unimaginable to me.
But if he was in the cockpit earlier, why did he leave? Probably due to his psychological situation. Or maybe he was also partially affected by hypoxia--his voice sounded exhausted in the cockpit voice recorder and he was not able to think properly. We will never know for sure.
But he didn't give up. When he returned, he tried to contact the ground. Five Maydays were heard in the cockpit recorder. But no one could hear him.
Subsequent developments
Helios airways was at first re-branded to 'Ajet' and then after about one year it was shutdown due to bankruptcy.
Helios Airways' Chief Engineer, CEO, Operations Manager, and Chief Pilot were charged with 119 counts of manslaughter and causing death by recklessness/negligence. In 2013, they were given 10 year imprisonments, but on further appeal they were given option to buyout their sentences for around €75,000 each.
The lawsuit against Boeing for keeping two similar type of alarms were never heard in US courts. However, Boeing rectified the alarm problem and also added two more lights to indicate when pressurization is changed to manual.
Image: Andreas Prodromou and his girlfriend Haris Charalambous's photo at memorial location.
This answer is in tribute to Andreas Prodromou and everyone who was on-board that fateful flight. On the hill near Athens where the plane crashed there are faded photographs of many of the passengers, bleached by the bright Mediterranean sun; they gaze over the rugged ancient terrain, silent witnesses to one of the world's most bizarre and tragic plane accidents.
Sources,
There are theories which suggest that similar incident may have happened on-board Malaysian Airlines flight MH370.
This answer was written because many people asked me here :- What are the strangest airplane accidents/Incidents? So you may want to read it.
Here is the recording of conversation between F-16 pilots and the ground. It is in Greek, so I don't understand what they are saying. :- Page on youtube.com
-By Kshitij Salgunan (An airplane enthusiast)
Situation
A Helios Airways Boeing 737 is circling the city of Athens for more than two hours in a holding pattern. There is no communications from the plane even after multiple attempts. The Greek air force sends two of its fighter jets to investigate the situation. One of them is in a shooting position behind the 737 while the other one is trying to visually assess the situation. The fighter pilot can see passengers on their seats but none of them are moving or reacting to the presence of a fighter jet. There is one person on the co-pilots seat, slumped over the controls and appears to be unconscious. The captain's seat is vacant.
Then the fighter pilot radios that there is one other person moving in the cockpit! But this person is not communicating with the fighter pilot. This person sits on the captain's seat and after few minutes, the plane makes a sudden left turn and starts to descent to a lower altitude.
Sounds like a movie?
This true story is as suspenseful as a good thriller movie. I strongly suggest that you watch this documentary of Air Crash Investigation. It is highly dramatized and made nearly like a movie itself.
Air Crash Investigation - Ghost Plane - Helios Flight 522
But if you choose to read, then continue.
What happened to the crew and passengers? And who is flying the plane?
The story of Helios flight 522 begins with Andreas Prodromou, a flight attendant who is preparing the cabin for the early morning flight from Cyprus to Athens, Greece. The date is 14th August 2005. Andreas is actually not supposed to be working today, but he volunteered for this flight because he wants to spend some time with his girlfriend who is also a flight attendant for Helios. Andreas has bigger plans, he wants to become a professional pilot one day. He also has a commercial pilot license, but he is not yet qualified to fly big planes such as a Boeing 737. He had taken the job as a steward at Helios Airways after failing to find work as a pilot, despite strong pressure from his family not to take a position for which he was over-qualified.
Helios is a small low cost airline with just 3 planes. The crew of the entire airline has been working together for a few years and know each other personally. 115 passengers boarded the plane and got seated for the flight.
In the cockpit, Hans-Jürgen Merten, a 58-year-old German contract pilot hired by Helios for the holiday season, was the captain. He had been flying for 35 years and had accrued 16,900 flight hours. Pampos Charalambous, 51, a Cypriot who flew exclusively for Helios, served as the first officer. He had accrued 7,549 flight hours throughout his career. They were preparing the plane for take off. It was a routine procedure to check all important systems before the flight.
Louisa Vouteri, a 32-year-old Greek national living in Cyprus, replaced a sick colleague as the chief purser (chief flight attendant). The purser oversees the flight attendants by making sure airline passengers are safe and comfortable.
At 9:07AM, Helios 522 takes off from Larnaca International Airport. As the flight reached 12,000 ft, a warning alarm starts beeping in the cockpit. The pilots identifies the alarm as 'take off configuration warning'. But they are confused because the take off configuration warning only sounds when the plane is on the ground, and it means that the plane is not ready for the flight. It is never supposed to happen when the plane is in the air.
Unsure why the alarm is beeping, the captain contacts the Helios operation center for support from the ground engineers. He radios that his "take-off configuration warning is on" and "cooling equipment normal and alternate off line".
After few minutes, their equipment cooling warning lights came on to indicate low airflow through the cooling fans, accompanied by their master caution alarm. He conveys this to the ground engineer. He then repeatedly stated that the "cooling ventilation fan lights were off".
The previous day, when the aircraft arrived from London Heathrow, the previous flight crew had reported a frozen door seal and abnormal noises coming from the right aft service door. They requested a full inspection of the door. The inspection was carried out by a ground engineer who then performed a pressurization leak check.
In the cabin, passengers did not know about the situation in the cockpit until the passenger oxygen masks came down. The cabin crew requested everyone to remain in their seats and put on the oxygen masks. The flight attendants also put on their own oxygen masks and waited for further information from the cockpit.
The pilots, unaware the oxygen masks were coming down in the cabin, continued their troubleshooting with the ground engineers. The engineer (the one who had conducted the pressurization leak check) asked "Can you confirm that the pressurization panel is set to AUTO?" The captain, disregarded the question and instead asked in reply, "Where are my equipment cooling circuit breakers?". The ground engineers reply that it is behind the captain's seat. They now lose radio contact with the plane.
The plane is still climbing and on course to Athens. The passengers have not received any information from the cockpit.
After two hours, the Helios 522 is circling the city of Athens. Nineteen attempts were made to contact the plane but there was no response. The air traffic controllers in Athens got worried about the possibility of a terrorist attack. A plane crash in the city can cause large loss of life. They informed the military about the runaway aircraft. The Greek air-force quickly sends two F-16 fighter jets to investigate the situation.
The F-16 pilots reported seeing the pilot's seat empty and the co-pilot slumped over the controls, possibly unconscious. They observed no movement in the cabin. They also reported about the oxygen masks in the cabin. The F-16s shadowed the jet and tried to visually establish contact with the plane.
Then, the F-16 pilots saw a person moving in the cockpit. This person sits on the captain's seat and takes over the controls. For the first time, this person acknowledges the fighter pilots by waving hands.
The plane suddenly turns left and starts descending. The F-16s follows the plane. It first levels off at 10,000 feet and then again descends to 2,500 feet. Three hours after the Helios 522 took off from Cyprus, the plane slammed into the ground.
The F-16 pilot radios that Helios 522 has crashed into barren hills near Grammatiko.
Firefighters and rescue teams rushes to the location, but there are no survivors.
It is the worst plane crash in the history of Greece.
Most of the passengers were from Cyprus. The small island nation of Cyprus declares three days of mourning.
Investigation
There were theories that all the passengers died in the air. But autopsies conducted on the bodies, revealed that they died on impact. But if the passengers were alive then why didn't the F-16s see any movement?
DNA analysis on samples from the cockpit revealed that Andreas Prodromou was inside the cockpit. This raised many questions about whether the flight attendant was trying to save the plane or trying to deliberately crash the plane.
The plane's black box revealed that the last left turn which the F-16s saw happened because the left engine switched off due to lack of fuel. The plane had ultimately crashed due to the lack of fuel.
It was soon discovered that the engineer who conducted the pressurization test on the day before the crash forgot to turn this knob back to auto after concluding the test. After the aircraft returned to service, the flight crew overlooked the pressurization system state on three separate occasions: during the pre-flight procedure, the after-start check, and the after take-off check. During these checks, no one in the flight crew noticed the incorrect setting since no one typically changes the pressurization knobs.
As the aircraft climbed, the pressure inside the cabin gradually decreased. As it passed through an altitude of 12,000 feet (3,670 m), the cabin altitude warning horn sounded. The warning should have prompted the crew to stop climbing, but it was misidentified by the crew as a take-off configuration warning, which signals that the aircraft is not ready for take-off, and can only sound on the ground. They misidentified it because most pilots will never ever hear cabin altitude warning in their entire careers, and because it also sounds similar to the take-off configuration warning. Boeing was blamed for making two similar sounding warning alarms.
When the cockpit voice recorder (a part of black box) was played, the investigators heard 5 different Mayday calls from Andreas Prodromou. He sounded exhausted and tired. He was trying to save the plane. But the calls were not heard by the air traffic controller because the radio was still tuned to the frequency set for Cyprus.
The Story continues...
The crew must have waited a few minutes for further information from the captain after the oxygen masks dropped.
But they may not have waited forever. After some time, they may have tried to contact the cockpit using the intercom. Andreas was seated at the back of the cabin.
The passengers oxygen mask only contains enough oxygen for 12 minutes after which everyone on board became unconscious due to hypoxia (oxygen deprivation). No alarm shows the pilots that the oxygen masks have dropped in the cabin, and pilots mask needs to be manually used. The pilots didn't wear their own oxygen masks because they didn't consider this as a problem.
At that altitude, anyone without the oxygen mask can fall unconscious within 20 to 60 seconds. This is why flight attendants always advise in their flight emergency procedures to put your oxygen mask on first before helping children or other passengers.
Oxygen deprivation can also decrease cognitive thinking ability which may be the reason why the pilots were acting slow. The airplane continued its journey on autopilot to Athens where it entered the holding pattern above the city.
The standard procedure when the oxygen masks come down is to descend to a lower altitude where the passengers can breath normally.
When several calls to the cabin was unanswered, and when the plane continued to climb, Andreas must have tried to come forward using the additional passenger oxygen masks. The passengers and crew must have gone unconscious after the 12 minutes. Hypoxia is no more painful than falling asleep. Andreas was a Scuba diver and had served in the special forces; his training may have helped him stay conscious longer than the others on the plane. A Boeing 737 has four portable oxygen masks, and he must have used one of those to stay conscious till the end of the flight.
After 9/11 incident, all passenger planes have nearly unbreakable cabin door, so flight attendants cannot directly access the pilots. He banged the cockpit door several times, and when the pilots didn't respond he typed the security code and entered the cockpit. The sound of the door-bangs and the clicking of the number pad are recorded in the cockpit voice recorder (a part of black box).
DNA from a pilot was also found on one of the portable oxygen masks. So Andreas may have tried to revive the pilots using the portable oxygen masks.
Although he held a UK Commercial Pilot License he was not qualified to fly the Boeing 737. Crash investigators concluded that Prodromou's experience was insufficient for him to gain control of the aircraft under the circumstances.
As it approached Athens, it was a ghost plane. By then, the passengers and crew would have been in an irreversible coma.
Ten minutes after the loss of power from the left engine, the right engine also flamed out, and just before 12:04 the aircraft crashed into the hills near Grammatiko.
Andreas may have also entered the cockpit earlier. But he was in an impossible situation. Just imagine being in his situation. Imagine standing alone in the cabin while everyone he works with and all passengers are dying. Even his girlfriend was unconscious and dying. He also knows that he is also going to die when his oxygen runs out. His psychological situation is unimaginable to me.
But if he was in the cockpit earlier, why did he leave? Probably due to his psychological situation. Or maybe he was also partially affected by hypoxia--his voice sounded exhausted in the cockpit voice recorder and he was not able to think properly. We will never know for sure.
But he didn't give up. When he returned, he tried to contact the ground. Five Maydays were heard in the cockpit recorder. But no one could hear him.
Subsequent developments
Helios airways was at first re-branded to 'Ajet' and then after about one year it was shutdown due to bankruptcy.
Helios Airways' Chief Engineer, CEO, Operations Manager, and Chief Pilot were charged with 119 counts of manslaughter and causing death by recklessness/negligence. In 2013, they were given 10 year imprisonments, but on further appeal they were given option to buyout their sentences for around €75,000 each.
The lawsuit against Boeing for keeping two similar type of alarms were never heard in US courts. However, Boeing rectified the alarm problem and also added two more lights to indicate when pressurization is changed to manual.
This answer is in tribute to Andreas Prodromou and everyone who was on-board that fateful flight. On the hill near Athens where the plane crashed there are faded photographs of many of the passengers, bleached by the bright Mediterranean sun; they gaze over the rugged ancient terrain, silent witnesses to one of the world's most bizarre and tragic plane accidents.
Sources,
- Helios Airways Flight 522
- Most photos used in this post are from Ciniflix's Air crash Investigation.
There are theories which suggest that similar incident may have happened on-board Malaysian Airlines flight MH370.
This answer was written because many people asked me here :- What are the strangest airplane accidents/Incidents? So you may want to read it.
Here is the recording of conversation between F-16 pilots and the ground. It is in Greek, so I don't understand what they are saying. :- Page on youtube.com
-By Kshitij Salgunan (An airplane enthusiast)
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