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. Rescue teams located wreckage near the community of Grammatiko 40 km (25 mi) from Athens. All 121 on board were killed.