On August 14, 2005, a Helios Airways Boeing 737-300 (5B-DBY) crashed near the village of Grammatiko, in a rural area of Greece, just outside of Athens. All 115 passengers, including Greek, Cypriot and Australian nationals, plus six crew members onboard, were killed. It remains the worst air disaster in Greek aviation history.
The tale behind the final hours of the ill-fated flight is chilling. However, the disaster could have been much worse had it not been for the heroic actions of one of the cabin crew members, Andreas Prodromou.
This is his story.
Earlier Issues
The aircraft had been operating Flight ZU522, which was a scheduled service from Larnaca International Airport to Prague, with a layover in Athens.
In charge of the flight was Captain Hans-Jürgen Merten. The 59-year-old German, later described by colleagues as “a man of few words”, had previously flown for East German airline Interflug and later UK low-cost carrier easyJet, accruing over 16,900 flight hours, 5,500 of which had been on the 737. He was assisted by First Officer Pampos Charalambous, a 51-year-old Cypriot, who had worked for Helios for five years, amassing 7,549 hours, 3,9991 of which were on the 737.
In the cabin, the four crew were led by Louisa Vouteri, a 32-year-old Greek national living in Cyprus. Vouteri, who was planning her marriage the following month, had replaced a colleague who had earlier reported sick for the duty. She was assisted by 25-year-old Andreas Prodromou, who had also been called out just before the flight to work with his girlfriend and fellow crew member, Haris Charalambous. The pair had also planned to get married.
Before Flight 522, the aircraft had flown in from London, after which the cabin crew reported issues with the right aft service door. The crew wrote in the plane’s tech log: ‘Aft service door (starboard) seal around door freezes & hard bangs are heard during flt [flight].’ That night, a pressure check was carried out in Larnaca by the airline’s engineers and the 737 was deemed serviceable for the next day’s flight to Prague.
The Fateful Flight
The crew members reported for flight ZU522 at 05:00hrs UTC and held a briefing before preparing the cabin for boarding. A short time later, everyone was on board and at 06:07hrs, the aircraft took off for its first leg to Athens.
Just over five minutes after takeoff, the cabin altitude warning alarm began to sound in the flight deck as they passed through 12,000 feet. Confused, the flight crew believed that the alarm was a takeoff configuration warning (the alert sound was identical for both) and continued the climb.
Then various other alarms began to sound, including the master caution and passenger oxygen lights at an altitude of around 16,000 feet. At 18,000 feet, the oxygen masks in the cabin automatically deployed.
Captain Merten radioed the airline’s operations centre and reported “the takeoff configuration warning on” and “cooling equipment normal and alternate off line.” Merten then spoke to the engineer who had conducted the pressurisation leak check, who asked if the pressurisation panel had been set to AUTO.
By now, the symptoms of hypoxia were beginning to set in, and as the 737 climbed through 28,900 feet, Captain Merten replied, “Where are my equipment cooling circuit breakers?” The engineer on the ground replied, “Behind the Captain’s seat.” This was the final communication before both pilots fell unconscious. The CVR led investigators to believe that the captain had got out of his seat to check the circuit breakers but was overcome by the lack of oxygen.
Ghost Plane
With the aircraft’s autopilot set, the 737 continued its climb towards Athens, levelling off at 34,000 feet. Nicosia ATC repeatedly attempted to contact the stricken jet, but there was no reply.
As per their training, the cabin crew would have donned their oxygen masks and remained seated, waiting for a descent to begin or for the pilots to make an announcement. Neither came.
At 10:40hrs, Flight 522 entered the holding pattern for Athens and remained here for the next 70 minutes, flying in a loop over the Greek capital. Continued attempts to contact the ghost plane remained unanswered.
It was at this point that the Hellenic Air Force dispatched two F-16 fighter jets to establish visual contact with the 737, which they achieved at 11:24 while the aircraft was entering its sixth loop of the holding pattern.
They reported that they could see the first officer slumped motionlessly at the controls, and the captain’s seat was empty. While the cabin was reportedly in darkness, they could see that the passenger oxygen masks, which only last for 12 minutes, had been deployed and that three passengers could be observed motionless wearing their oxygen masks.
Then, at 08:49hrs, one of the air force pilots witnessed a person wearing “a light blue shirt and dark vest” who they believed was not wearing an oxygen mask entering the flight deck and taking the captain’s seat. This was backed up by data recovered from the Cockpit Voice Recorder (CVR), which revealed sounds that matched the sounds of someone using the flight deck door access code and the door opening. He put on a set of headphones and appeared to place his hands on the panel directly in front of him. The fighter pilot attempted to attract his attention, but to no avail. DNA tests later revealed that this was crew member Andreas Prodromou, who held a pilot’s licence but was not qualified to fly a 737.
A minute later, the left engine flamed out due to fuel exhaustion, and the jet began to descend. Prodromou then sent two desperate MAYDAY messages, picked up on the CVR: “MAYDAY, MAYDAY, MAYDAY, Helios Airways Flight 522 Athens … (unintelligible word)”. A few seconds later, another “MAYDAY, MAYDAY”, now with a much weaker voice, was recorded.
As the 737 descended through 7,000 feet, Prodromou finally appeared to acknowledge the presence of the F-16s, making a hand motion. The pilot of the fighter jet responded with a hand signal for the person to follow him down towards the airport. Prodromou pointed downwards but did not follow.
Instead, at 08:59hrs, the aircraft’s heading changed to a southwesterly direction. This is believed to have been Prodromou’s heroic last effort to guide the stricken airliner away from the Greek capital. The F-16 pilot also later reported that the way in which the 737 impacted the ground appeared to indicate that Prodromou attempted to level the wings to alleviate the impact.
The right-hand engine then flamed out as the aircraft descended through 7,000 feet before continuing a rapid descent and impacting hilly terrain near Grammatiko village, around 33km northwest of Athens at 09:03:32hrs UTC.
Locked Out?
The subsequent investigation by the Hellenic Air Accident Investigation and Aviation Safety Board (AAISB) revealed that the engineer carrying out the check on the rear aft service door failed to reset a crucial air conditioning switch from MANUAL to AUTO after pressurising the aircraft. The pilots subsequently missed this error during their pre-departure checks, and as the Boeing jet climbed out of Larnaca, the cabin failed to pressurise. The rest, sadly, was history.
Four portable oxygen bottles were later retrieved from the wreckage, three of which were found with their valves in the open position. This led investigators to concur that someone on board, most likely Prodromou, had used them.
The CVR only contained the last 30 minutes of the flight, and as the whole flight lasted almost three hours, it is unclear what actions the cabin crew took during the event. It was believed that Prodromou had been positioned in the rear galley and used portable oxygen bottles to reach the flight deck.
Quite why it took him so long remains unclear. However, the incident occurred shortly after the introduction of locked flight deck doors following the 9/11 terrorist attacks. At the time, only the senior crew member was allowed to know the access code. Could Prodromou have been trying codes at random before finally finding the correct one? Maybe he finally found the code on the unconscious senior crew member? Sadly, we will never know.
But what we do know is that the young man’s heroic actions, changing the aircraft’s course away from Athens, potentially saved hundreds of other lives.
To read more incredible stories of aviation heroes from our industry, click here.
Cover Image Credit: AAISB
© Confessions of a Trolley Dolly by Dan Air
What a heartbreaking story, thank you for sharing.