Helios Airways Flight 522

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Helios Airways Flight 522
Helios Airways Boeing 737-300 5B-DBY PRG 2005-3-31.png
5B-DBY, the aircraft involved in the accident, at Prague Airport in March 2005.
Accident summary
Date 14 August 2005 (2005-08-14)
Summary Loss of cabin pressurization resulting in crew incapacitation followed by fuel exhaustion
Site Grammatiko, Marathon, Greece
38°13.894′N 23°58.214′E / 38.231567°N 23.970233°E / 38.231567; 23.970233Coordinates: 38°13.894′N 23°58.214′E / 38.231567°N 23.970233°E / 38.231567; 23.970233
Passengers 115
Crew 6
Fatalities 121 (all)
Survivors 0
Aircraft type Boeing 737-31S
Aircraft name Olympia
Operator Helios Airways
Registration 5B-DBY
Flight origin Larnaca International Airport, Larnaca, Cyprus
Stopover Athens International Airport, Athens, Greece
Destination Prague Ruzyně Int'l Airport, Prague, Czech Republic

Helios Airways Flight 522 was a scheduled passenger flight from Larnaca, Cyprus, to Athens, Greece that on 14 August 2005 crashed, killing all 121 passengers and crew on board. A loss of cabin pressurization had incapacitated the crew, leaving the aircraft flying on autopilot until it ran out of fuel and descended into the ground.

It is the deadliest aviation accident in Greek history. Flight 522's loss marked the 69th crash of a Boeing 737 since it was brought into service in 1968. The crash is the fourth-deadliest involving a 737-300.


The aircraft involved in this incident was first flown on 29 December 1997 and had been operated by DBA in 1998 until it was leased by Helios Airways on 16 April 2004 and nicknamed Olympia, with registration 5B-DBY.[1] Aside from the downed aircraft, the Helios fleet consisted of two leased Boeing 737-800s and an Airbus A319-100 delivered on 14 May 2005. The aircraft had arrived in Larnaca from London at 01:25 that morning.[2] The flight was scheduled to leave Larnaca, Cyprus, at 09:00 am local time, and fly to Prague via Athens. The scheduled arrival time in Athens was 10:45 am.[3] Hans-Jürgen Merten, a 58-year-old German contract pilot hired by Helios for the holiday flights, was the captain. He had been flying for 35 years (including for Interflug before 1990) and had accrued 16,900 flight hours. Pampos Charalambous, 51, a Cypriot who flew for Helios, served as the first officer and had worked exclusively for Helios for the last five years. Charalambous had accrued 7,549 flight hours throughout his career.[4] Louisa Vouteri, a 32-year-old Greek national living in Cyprus, replaced a sick colleague as the chief purser.[5]

Flight and crash[edit]

Flight path of Helios 522-en.svg
Date: 14 August 2005
All times EEST (UTC + 3h), PM in bold
Time Event
0900 Scheduled departure
0907 Departs Larnaca International Airport
0912 Cabin Altitude Warning sounds at
12,040 feet (3,670 m)
0914 Pilots report air conditioning problem
0920 Last contact with crew;
Altitude is 28,900 feet (8,809 m)
0923 Now at 34,000 feet (10,400 m);
Probably on autopilot
0937 Enters Athens flight information region;
Nicosia ATC informs Athens ATC that radio
contact has been lost[6]
1012–1050 No response to radio calls from Athens ATC
1045 Scheduled arrival in Athens
1054 Athens Joint Rescue Coordination Centre
alerted to possible renegade aircraft[7]
1105 Two F-16 fighters depart Nea Anchialos
1124 Located by F-16s over Aegean island of Kea
1132 Fighters see co-pilot slumped over,
cabin oxygen deployed, no signs of terrorism
1149 Fighters see an individual in the cockpit,
apparently trying to regain control of aircraft
1150 Left (#1) engine stops operating,
presumably due to fuel starvation
1154 CVR records two MAYDAY messages
1200 Right (#2) engine stops operating
1204 Aircraft crashes in mountains
near Grammatiko, Greece

When the aircraft arrived from London earlier that morning, 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.[2][8] The inspection was carried out by a ground engineer who then performed a pressurization leak check. In order to carry out this check without requiring the aircraft's engines, the pressurisation system was set to "manual". However, the engineer failed to reset it to "auto" on completion of the test.[9]

After the aircraft was returned into service, the flight crew overlooked the pressurisation 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.[10] The aircraft took off at 9:07[3] with the pressurisation system still set to "manual", and the aft outflow valve partially open.[11]

As the aircraft climbed, the pressure inside the cabin gradually decreased. As it passed through an altitude of 12,040 feet (3,670 m), the cabin altitude warning horn sounded.[3] The warning should have prompted the crew to stop climbing,[12] 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.[12]

In the next few minutes, several warning lights on the overhead panel in the cockpit illuminated. One or both of the equipment cooling warning lights came on to indicate low airflow through the cooling fans (a result of the decreased air density), accompanied by the master caution light. The passenger oxygen light illuminated when, at an altitude of approximately 18,000 feet (5,500 m), the oxygen masks in the passenger cabin automatically deployed.[13][14]

Shortly after the cabin altitude warning sounded, the captain radioed the Helios operations centre and reported "the take-off configuration warning on" and "cooling equipment normal and alternate off line".[3] He then spoke to the ground engineer and repeatedly stated that the "cooling ventilation fan lights were off".[3] 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, possibly experiencing the onset of the initial effects of hypoxia,[15] disregarded the question and instead asked in reply, "Where are my equipment cooling circuit breakers?".[14] This was the last communication with the aircraft.[16]

The aircraft continued to climb until it leveled off at FL340, approximately 34,000 feet (10,000 m).[14] Between 09:30 and 09:40, Nicosia ATC repeatedly attempted to contact the aircraft, without success.[14] At 09:37, the aircraft passed from Cyprus Flight Information Region (FIR) into Athens FIR, without making contact with Athens ATC.[14] Nineteen attempts to contact the aircraft between 10:12 and 10:50 also met with no response,[17] and at 10:40 the aircraft entered the holding pattern for Athens Airport, at the KEA VHF omnidirectional range, still at FL340.[18] It remained in the holding pattern, under control of the auto-pilot, for the next 70 minutes.[18]

Two F-16 fighter aircraft from the Hellenic Air Force 111th Combat Wing were scrambled from Nea Anchialos Air Base to establish visual contact.[19] They intercepted the passenger jet at 11:24 and observed that the first officer was slumped motionless at the controls and the captain's seat was empty.[20] They also reported that oxygen masks were dangling in the passenger cabin.[18]

At 11:49, flight attendant Andreas Prodromou entered the cockpit and sat down in the captain's seat, having remained conscious by using a portable oxygen supply.[21][22] Prodromou held a UK Commercial Pilot License,[23] but 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.[22] Prodromou waved at the F16s very briefly, but almost as soon as he entered the cockpit, the left engine flamed out due to fuel exhaustion[22] and the plane left the holding pattern and started to descend.[24] Ten minutes after the loss of power from the left engine, the right engine also flamed out,[24] and just before 12:04 the aircraft crashed into hills near Grammatiko, 40 km (25 mi) from Athens, killing all 121 passengers and crew on-board.[24]


The aircraft was carrying 115 passengers and a crew of six. The passengers included 67 due to disembark at Athens, with the remainder continuing to Prague. The bodies of 118 people were recovered.[25] The passenger list included 93 adults and 22 children. The passengers comprised 103 Cypriot nationals and 12 Greek nationals.[26]

Nationality Passengers Crew Total
 Cyprus 103 4 107
 Germany 0 1 1
 Greece 12 1 13
Total 115 6 121


5B-DBY at London Luton Airport in 2004

The flight data recorder and cockpit voice recorder were sent to Paris for analysis.[27][28] The CVR recording enabled investigators to identify Prodromou as the flight attendant who entered the cockpit in order to try to save the plane. He called "Mayday" five times but, because the radio was still tuned to Larnaca, not Athens, he was not heard by ATC. His voice was recognized by colleagues who listened to the CVR recording.[29]

Many of the bodies recovered were burned beyond recognition by the post-impact fire.[30] Autopsies on the crash victims showed that all were alive at the time of impact, but it could not be determined whether they were conscious as well.[31]

The emergency oxygen supply in the passenger cabin of this model of Boeing 737 is provided by chemical generators that provide enough oxygen, through breathing masks, to sustain consciousness for about 12 minutes,[32] normally sufficient for an emergency descent to 10,000 feet (3,000 m), where atmospheric pressure is sufficient to sustain life without supplemental oxygen. Cabin crew have access to portable oxygen sets with considerably longer duration.[33]

The Hellenic Air Accident Investigation and Aviation Safety Board (AAIASB) listed the direct causal chain of events that led to the accident as:

  • non-recognition by the pilots that the pressurisation system was set to "manual",
  • non-identification by the crew of the true nature of the problem,
  • incapacitation of the crew due to hypoxia,
  • eventual fuel starvation,
  • impact with the ground.[10]

Previous pressurization problems[edit]

On 16 December 2004, during an earlier flight from Warsaw, the same aircraft experienced a rapid loss of cabin pressure and the crew made an emergency descent. The cabin crew reported to the captain that there had been a bang from the aft service door, and that there was a hand-sized hole in the door's seal. The Air Accident and Incident Investigation Board (AAIIB) of Cyprus could not conclusively determine the causes of the incident, but indicated two possibilities: an electrical malfunction causing the opening of the outflow valve, or the inadvertent opening of the aft service door.[34]

The mother of the first officer killed in the crash of Flight 522 claimed that her son had repeatedly complained to Helios about the aircraft getting cold. Passengers also reported problems with air conditioning on Helios flights.[35] During the 10 weeks before the crash, the aircraft's environmental control system was repaired or inspected seven times.[36][37]

A 2003 flight of a Boeing 737 between Marseilles and London Gatwick showed that a cabin-wide pressurization fault can go unrecognized by the flight crew.[not in citation given] A problem was first noticed when the crew began to feel some discomfort in their ears. This was shortly followed by the cabin altitude warning horn which indicated that the cabin altitude had exceeded 10,000 feet and this was seen to continue to climb on the cockpit gauge. At the same time, the primary AUTO mode of the pressure control failed, shortly followed by the secondary STBY mode. The crew selected the first manual pressure control mode, but were unable to control the cabin altitude. An emergency descent and subsequent diversion to Lyon was carried out. The failure of the pressurization control system was traced to burnt electrical wiring in the area aft of the aft cargo hold. The wiring loom had been damaged by abrasion with either a p-clip or 'zip' strap that, over time, exposed the conductors, leading to short circuits and subsequent burning of the wires. There was no other damage. The wiring for all the modes of operation of the rear outflow valve, in addition to other services, run through this loom.[38]


News media widely reported that shortly before the crash a passenger sent a text message indicating that one of the flight crew had become blue in the face, or roughly translated as: "The pilot is dead. Farewell, my cousin, here we're frozen, the pilot is blue." Police later arrested Nektarios-Sotirios Voutas, who admitted that he had made up the story and given several interviews in order to get attention.[39][40] Voutas was tried by a court of first instance on 17 August 2005 and received a suspended six-month imprisonment sentence under a 42-month probation term.[41]

Another hoax involved photographs allegedly showing the aircraft being chased by Greek fighter jets. The photos were actually of a Helios 737-800 (rather than the crashed 737-300) with the registration altered and the fighter jets added.[42]

Subsequent developments[edit]

The company announced successful safety checks on their Boeing fleet on 29 August 2005 and put them back into service. It later renamed itself from "Helios Airways" to "αjet". Authorities in Cyprus detained the company's aircraft and froze the company's bank accounts, and the airline stopped operating on 11 June 2006.

In March 2011, the Federal Aviation Administration in the United States released an Airworthiness Directive requiring all Boeing 737 aircraft from −100 to −500 models to be fitted with two additional cockpit warning lights. These would indicate problems with take-off configuration or pressurization. Aircraft on the United States civil register were required to have the additional lights by 14 March 2014.[43]

Lawsuits and criminal proceedings[edit]

Families of the dead filed a lawsuit against Boeing on 24 July 2007. Their lawyer, Constantinos Droungas, said, "Boeing put the same alarm in place for two different types of dysfunction. One was a minor fault, but the other – the loss of oxygen in the cockpit – is extremely important." He also said that similar problems had been encountered before on Boeings in Ireland and Norway. The families sued for 76 million euros in compensation from Boeing.[44]

In early 2008, an Athens prosecutor charged six former employees with manslaughter over the incident. Reports at the time said the suspects were two Britons, one Bulgarian national and three Cypriots.[45]

On 23 December 2008, Helios Airways and four of its officials were charged in Cyprus with 119 counts of manslaughter and of causing death by recklessness/negligence. The four officials were former chief pilot Ianko Stoimenov, chairman of the board Andreas Drakos, chief executive officer Demetris Pantazis, and operations manager Giorgos Kikidis. The trial began in November 2009; the state prosecutors finished presenting their case in June 2011.[46][47][48] The case was dismissed, and the defendants acquitted, on 21 December 2011. The panel of judges hearing the case ruled that there was no "causal association between the defendants and the negligence they were charged with for the fatal accident".[49] An appeal was filed by the Cypriot Attorney-general, and in December 2012 the Supreme Court set aside the acquittal and ordered a new trial. Two months later, the retrial was dropped under double jeopardy rules, as the charges had already been heard in Athens.[50][51]

In December 2011, shortly after the end of the case in Cyprus, a trial began in a Greek magistrate's court in which chief executive officer Demetris Pantazis, flight operations manager Giorgos Kikkides, former chief pilot Ianko Stoimenov and chief engineer Alan Irwin were charged with manslaughter. All except Irwin had been previously charged and acquitted by the Cypriot authorities.[50] In April 2012 all were found guilty and sentenced to 10 years imprisonment and remained free on bail pending an appeal.[52]

As of August 2013, all defendants lost their appeal at the Athens High Court. Their sentence of 10 years was ordered to stand but the defendants were given the option to buy out their sentence for around €75,000 each. Greek investigators blamed the crash of the Helios Airways flight outside Athens on human error after Boeing 737-300 failed to pressurize after taking off from Larnaca Airport. Prosecutors in both countries blamed airline officials for cutting corners on safety operations while also saying that they failed to act on advice that the pilots did not meet the necessary aviation standards.[53]

Relatives of the dead filed a class action suit against the Cypriot government – specifically the Department of Civil Aviation – for negligence that led to the air disaster. They claim that the DCA was ignoring airlines' loose enforcement of regulations, and that in general the department cut corners when it came to flight safety.[45]

In popular culture[edit]

The Discovery Channel Canada / National Geographic TV series Mayday featured the accident in a Season 4 episode titled Ghost Plane.[54] The accident was featured again during Mayday season 6, in an episode titled Ripped Apart.[55]

See also[edit]


  1. ^ "737 Production list". Planespotters.net. Retrieved 13 March 2014. 
  2. ^ a b AAIASB final report, section 1.1, p. 3 (PDF page 15 of 198).
  3. ^ a b c d e AAIASB final report, section 1.1, p. 4 (PDF page 16 of 198)
  4. ^ "Ghost Plane." Mayday
  5. ^ "Two trying to save jet ID'd ." News24. Archived 7 January 2009 at the Wayback Machine.
  6. ^ AAIASB final report, section 1.1, p.5 (PDF page 17 of 198)
  7. ^ AAIASB final report, section 1.1, p.6 (PDF page 18 of 198)
  8. ^ AAIASB final report, section, pages 21–2 (PDF pages 33–34 of 198)
  9. ^ AAIASB final report, section 3.2.3, p. 159 (PDF page 171 of 198)
  10. ^ a b AAIASB final report, section 3.2.1, p. 159 (PDF page 171 of 198)
  11. ^ AAIASB final report, section 1.16.2, p. 66 (PDF page 78 of 198)
  12. ^ a b AAIASB final report, section 2.2.4, p. 121 (PDF page 133 of 198)
  13. ^ AAIASB final report, section 2.2.4, p. 122 (PDF page 134 of 198)
  14. ^ a b c d e AAIASB final report, section 1.1, p. 5 (PDF page 17 of 198)
  15. ^ AAIASB final report, section 2.2.4, p. 123 (PDF page 135 of 198)
  16. ^ AAIASB final report, section 2.2.5, p. 125 (PDF page 137 of 198)
  17. ^ AAIASB final report, section 1.1, pages 5–6 (PDF pages 17–18 of 198)
  18. ^ a b c AAIASB final report, section 1.1, p. 6 (PDF page 18 of 198)
  19. ^ "Helios Crash: Background information". Famagusta Gazette. Retrieved 22 July 2012. 
  20. ^ Don Phillips (16 August 2005). "Crash inquiry focuses on oxygen mask use". The New York Times. Retrieved 24 June 2007. The F-16 pilots reported seeing the co-pilot slumped in his seat and the captain's seat empty. 
  21. ^ by Gate9er (21 March 2014). "AIR CRASH INVESTIGATION - Ghost Plane Helios 522 (Greek subs) - Video Dailymotion". Web.archive.org. Archived from the original on 21 March 2014. Retrieved 30 August 2017. 
  22. ^ a b c AAIASB final report, section 2.2.7, p. 127 (PDF page 139 of 198)
  23. ^ AAIASB final report, section, p. 15 (PDF page 27 of 198)
  24. ^ a b c AAIASB final report, section 1.1, p. 7 (PDF page 19 of 198)
  25. ^ Greek "Αεροπορική τραγωδία" Flash.GR
  26. ^ Greek Ο κατάλογος των θυμάτων ERT[dead link]
  27. ^ AAIASB final report, section 1.11.1 "Cockpit Voice Recorder (CVR)", p. 39 (PDF page 51 of 198): "The CVR was taken to be transcribed at BEA (Bureau d’ Enquétes et d’ Analyses) in France"
  28. ^ AAIASB final report, section 1.11.2 "Flight Data Recorder (FDR)", p. 40 (PDF page 52 of 198): "The FDR was found near the right aft service door and was recovered from the accident site on 14 August 2005, the day of the accident (Photo – FDR). It was taken to the readout facilities of BEA and the read out began on 17 August 2005"
  29. ^ AAIASB final report, section 2.2.7 "Descent", p. 127 (PDF page 139 of 198): "During the initial descent, at 08:54:18 h, the CVR record contained a MAYDAY call from the person in the Captain’s seat. The call was not transmitted over the VHF radio; it was only picked up the CVR microphone. The second MAYDAY call was at 08:55:05h followed by a third one a few seconds later. Based on the fact that there was only one male cabin attendant on board the accident aircraft, that the voice on the CVR was identified by colleagues to match that of the male cabin attendant, and that the person that entered the cockpit was wearing a Helios cabin attendant uniform, the Board concluded that the person that entered the cockpit and made efforts to control the aircraft was the male cabin crew member."
  30. ^ AAIASB final report, section 1.13.1 "Medical Information", p. 57.
  31. ^ AAIASB final report, section 1.13.1 "Medical Information", p. 57 (PDF page 69 of 198): "The forensic report concluded that the aircraft occupants had heart function during the impact. The report noted that this did not necessarily imply that they were alert. The report further estimated that they were in deep non-reversible coma due to their prolonged exposure (over 2.5 h) to the high hypoxic environment."
  32. ^ AAIASB final report, section "Passenger Oxygen", p. 33 (PDF page 45 of 198): "Once any of the four masks of a PSU is pulled, a continuous flow of oxygen begins. It lasts approximately 12 minutes"
  33. ^ AAIASB final report, section "Passenger Portable Oxygen", p. 32 (PDF page 44 of 198): "The cylinders have a maximum capacity of 311 liters (11 cubic feet) of free oxygen when pressurized to 1 800 psi. The oxygen could be used either through a four liter per minute outlet, or through a two liter per minute outlet, resulting in an oxygen availability duration of 1h 17 minutes or 2h 35 minutes, respectively."
  34. ^ AAIASB final report, section, p. 102 (PDF page 113 of 198)
  35. ^ "news in.gr – Βεβαρημένο το παρελθόν του αεροσκάφους που συνετρίβη, σύμφωνα με μάρτυρες". In.gr. Retrieved 13 March 2014. 
  36. ^ AAIASB final report, section, p. 103 (PDF page 115 of 198)
  37. ^ "Helios 737 crashed with no fuel and student pilot at the controls" Radar Vector, 21 August 2005
  38. ^ http://www.aaib.gov.uk/cms_resources.cfm?file=/dft_avsafety_pdf_029046.pdf
  39. ^ Phillips, Don (16 August 2005). "Crash inquiry focuses on oxygen mask use". International Herald Tribune. Retrieved 24 June 2007. 
  40. ^ "Pilot 'alive when plane crashed'", CNN, 17 August 2005 Archived 18 January 2008 at the Wayback Machine.
  41. ^ "Hoax crash SMS: Man freed". News 24. 17 August 2005. Archived from the original on 30 September 2007. Retrieved 24 June 2007. 
  42. ^ "Fake Helios pictures identified", Flight International, 17 August 2005
  43. ^ Hradecky, Simon. "FAA requires separate configuration and cabin altitude warning lights on Boeing 737s". Aviation Herald. Retrieved 8 February 2011. 
  44. ^ "Cyprus air crash victims' families make 76 mln eur legal claim against Boeing". Forbes. AFX News. 25 July 2007. Archived from the original on 9 November 2007. Retrieved 26 July 2007. 
  45. ^ a b Elias Hazou (2009). "Five face manslaughter charges over Helios crash". Cyprus Mail. Archived from the original on 15 April 2009. 
  46. ^ Stefanos Evripidou (17 June 2011). "State wraps up Helios case". Cyprus Mail. Archived from the original on 19 June 2011. Retrieved 29 June 2011. 
  47. ^ "Five charged for Helios jet crash". BBC News. 23 December 2008. Retrieved 4 May 2010. 
  48. ^ "Cyprus files charges over airline disaster". Reuters. 23 December 2008. 
  49. ^ Elias Hazou (23 December 2011). "AG to appeal Helios ruling". Cyprus Mail. Archived from the original on 24 December 2011. Retrieved 23 December 2011. 
  50. ^ a b "Helios verdict due on Friday". Cyprus Mail. 18 April 2012. Archived from the original on 28 April 2012. Retrieved 22 April 2012. 
  51. ^ "Cyprus: Charges dropped for air crash defendants". KSL.com. 13 February 2013. Retrieved 23 May 2013. Attorney General Petros Clerides told The Associated Press that he dropped the charges because European Union laws stipulate that defendants tried and convicted in one EU country can't be tried for the same crime in another EU country. 
  52. ^ George Psyllides (21 April 2012). "Ten years for former Helios bosses". Cyprus Mail. Archived from the original on 21 April 2012. Retrieved 22 April 2012. 
  53. ^ "Helios remembered". Incyprus.philenews.com. 14 August 2013. Retrieved 13 March 2014. 
  54. ^ "Ghost Plane". Mayday. Season 4. 2007. Discovery Channel Canada / National Geographic Channel. 
  55. ^ "Ripped Apart". Mayday. Season 6. 2007. Discovery Channel Canada / National Geographic Channel. 

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