Summary
Highlights
The tragedy's chain of events began the previous night when engineer Alan Irwin performed a pressurization leak check. He switched the pressurization mode selector from 'auto' to 'manual' for the test, but critically failed to switch it back to 'auto' mode before the aircraft was released for its next flight.
The flight crew for 522, including Captain Hans-Jürgen Mettmann and First Officer Pampos Charalambous, had significant experience. However, Captain Mettmann had a history of procedural non-compliance, and First Officer Charalambous was known for rushing checklists. During their hurried pre-flight checks, both pilots failed to notice the pressurization mode selector was still in 'manual' mode.
Shortly after takeoff, as the plane climbed, the cabin failed to pressurize. Despite multiple indicators showing abnormally high cabin altitude, the pilots did not notice. A loud alarm started sounding at 12,000 feet, which was the 'cabin altitude warning alarm', but the pilots, under the effects of growing hypoxia, mistook it for a 'takeoff configuration warning'—a known glitch. This critical misinterpretation coupled with their failure to don oxygen masks immediately led to rapid incapacitation.
Captain Mettmann's increasingly strange communication with ground engineer Alan Irwin, discussing ventilation cooling errors and circuit breakers, indicated his hypoxic state. Irwin, baffled, specifically asked about the pressurization mode selector but received no coherent reply. The line went silent 13 minutes after takeoff, leaving Irwin confused but believing he had addressed the pilot's issues, unaware of the impending catastrophe. Passengers in the cabin would have been experiencing panic and rapidly running out of oxygen.
After 9 minutes of silence, Helios dispatch attempted to contact the flight, then Athenian air traffic control. The plane entered Athens airspace but became unresponsive, eventually entering an automated holding pattern over the Greek island of Kea. At 8:23 AM, two F-16 fighter jets were dispatched. They observed First Officer Charalambous slumped over the controls and Captain Mettmann absent from the cockpit. All passengers were motionless, with oxygen masks dangling, indicating the cabin was compromised.
During the plane's tenth holding pattern, F-16 pilots observed someone, later identified as flight attendant Andreas Prodromou (a qualified pilot), making their way into the cockpit. He tried to take control, but the left engine failed due to fuel deprivation, causing a rapid descent. Prodromou attempted to communicate but was on the wrong frequency, weakly uttering 'Mayday, Mayday' into the void. The right engine also failed shortly after.
At 9:03 AM, Flight 522 crashed into the hills outside Grammatico Village at 400 mph, killing all 121 occupants. Investigations revealed most passengers were alive but unconscious at the time of impact. The subsequent 186-page report highlighted multiple failures, including the pressurization oversight, crew errors, and a dangerous organizational culture at Helios Airways. Questions arose about why cabin crew didn't intervene sooner or communicate, theorizing they may have incapacitated themselves while trying to assist others with limited oxygen. Helios Airways ceased operations in 2006. Legal battles followed, with families suing Boeing and Helios officials, including Alan Irwin, charged with manslaughter, though many convictions were later appealed or settled out of court. A memorial now stands at the crash site, a grim reminder of the lives lost in this preventable tragedy.
On August 14, 2005, Helios Airways flight 522, en route from Cyprus to Prague via Athens, went silent for over an hour at 35,000 ft. Two F-16 fighter jets were dispatched to investigate and found the pilots incapacitated and the cabin in disarray, signaling an unprecedented disaster.