High Quality Content by WIKIPEDIA articles! Helios Airways Flight 522 (HCY 522 or ZU522) was a Helios Airways Boeing 737–300 flight that crashed into a mountain on 14 August 2005 at 12:04 EEST, north of Marathon and Varnavas, Greece, whilst flying from Larnaca, Cyprus. A lack of oxygen incapacitated the crew, leading to the plane`s eventual crash after running out of fuel. Rescue teams located wreckage near the community of Grammatiko, 40 km (25 mi) from Athens. All 121 on board were killed.