A timeline of events leading up to the crash Sunday of a Cypriot airliner in Greece, as released by the Greek government. All 121 people aboard were killed.

9:00 a.m. — Helios Airlines Flight ZU522, a Boeing 737 carrying 115 passengers and six crew members, takes off from Larnaca International Airport in Cyprus, heading for Prague, Czech Republic, with a stopover in Athens.

9:37 a.m. — Plane enters Greek air space, identified by Greece's Civil Aviation Authority.

10:07 a.m. — Control tower at Athens International Airport unable to establish communication with the plane.

10:20 a.m — Air traffic controllers notify Cypriot counterparts who say plane reported a problem with air-conditioning system before entering Greek airspace.

10:25 a.m. — Greek Civil Aviation Authority notifies Defense Ministry's national search and rescue center.

10:30 a.m. — Defense ministry issues a Renegade alert, standard aviation procedure when planes fail to respond to control tower.

10:55 a.m. — Two F-16 fighter jets scramble to locate airliner.

11:20 a.m. — Fighter jets make visual contact with airliner over Aegean island of Kea, but unable to communicate with pilots.

11:25 a.m. — Fighter jets approach plane, report that co-pilot appears unconscious, other pilot not in cockpit, oxygen masks dangling inside cabin.

12:05 p.m. — Airliner crashes near town of Grammatiko, about 25 miles north of Athens.