On an August morning in 2005, what began as a routine flight from Cyprus to Athens turned into one of the most haunting ...

Why was this Helios airways 737 silent for over 2 hours before crashing into the Greek countryside, killing all on board? And who was the mystery person spotted in the cockpit by the fighter pilots ...

A lack of oxygen in the cabin incapacitated Helios Airways Flight 522's crew, and the plane eventually crashed into a mountain after running out of fuel.