The full story of a doomed flight dubbed a "ghost plane" has been revealed after it flew for hours with unconscious passengers.
The crashing of Helios Airways Flight 522 claimed the lives of all 115 passengers and six crew members as it unfolded in the skies over Greece on August 14, 2005.
The aircraft lost communication and eventually crashed into mountainous terrain near Grammatiko, per the Mirror.
The Boeing 737-300, nicknamed 'Olympia,' was en route from Larnaca International Airport in Cyprus to Prague, with a scheduled stop in Athens.
When air traffic controllers failed to receive any communication for over an hour, the Greek military dispatched two F-16 fighter jets to investigate.
They found the aircraft circling at 35,000 feet, with disaster imminent.
Less than three hours after takeoff, the plane crashed, killing everyone on board.
The flight crew consisted of 58-year-old Captain Hans-Jürgen Merten, a contract pilot with Helios Airways, and First Officer Pampos Charalambous, a 51-year-old Cypriot citizen who had been with the airline for five years.
Despite their combined experience of nearly 25,000 flight hours, including almost 10,000 on Boeing 737s, a fatal mistake was made shortly after takeoff.
When the cabin altitude warning horn sounded, the crew mistakenly believed it was the takeoff configuration warning, as the two alarms had identical sounds.
They chose to ignore it, continuing their ascent. As the plane climbed, the cabin began to lose pressure, but the crew remained unaware of the slow oxygen depletion.
Seven minutes into the flight, the pilots reported an air conditioning issue to the airline's operations center.
By the time the aircraft reached 18,000 feet, oxygen masks deployed in the cabin, but the crew was already beginning to experience the effects of hypoxia - insufficient oxygen - leading to confusion and incapacitation.
According to reports from the Daily Star, the plane leveled off at 34,000 feet, well above the safe oxygen threshold. At this point, the crew had lost consciousness, and the Boeing 737 circled on autopilot.
Efforts by air traffic control to contact the aircraft were unsuccessful, prompting the deployment of two Greek F-16 fighter jets.
The fighter pilots made a chilling discovery: the captain’s seat was empty, and the first officer was slumped over the controls, unconscious. Inside the cabin, oxygen masks dangled from the ceiling, but the passengers were motionless.
The only person who managed to stay conscious was flight attendant Andreas Prodromou, who used a portable oxygen supply to enter the cockpit in a desperate attempt to save the flight.
Prodromou, who held a UK Commercial Pilot License but was not qualified to fly a Boeing 737, briefly waved to the fighter jets before the aircraft’s left engine failed.
Despite knowing he would not survive, the 25-year-old attempted to steer the plane away from Athens, likely hoping to minimize further casualties by crashing in a rural area.
Ten minutes after the left engine failed, the right engine also gave out, and the aircraft plunged into a hillside 25 miles from Athens.
The crash and resulting fireball left most bodies burned beyond recognition, with autopsies revealing that many passengers were still alive at the time of impact.
Investigations uncovered multiple systemic failures at Helios Airways. According to Simple Flying, the airline had experienced ongoing issues with the aircraft’s air conditioning system in the weeks leading up to the crash, prompting seven separate inspections. The night before the accident, crew members reported hearing banging sounds and seeing ice on one of the doors.
Following the previous flight, Helios engineers performed a pressurization test, switching the system from automatic to manual.
However, they failed to return the setting to automatic after the inspection, an oversight that ultimately led to the aircraft’s unpressurized climb out of Larnaca.
Helios Airways’ staff also missed the error during their pre-flight checks. As a result, the plane took off completely unpressurized, setting the stage for disaster.
