Scattered across a mountain north of Athens, all that remains intact of the Helios Airways Boeing 737 that crashed on Sunday is a splintered piece of the tail fin.All 121 passengers and crew were killed after the aircraft apparently suffered a loss of cabin pressure or oxygen. Flight HCY522 left Larnaca in Cyprus at 9 a.m. local time, bound for Prague, it lost contact 90 minutes later. Why, remains a mystery. Greece scrambled two F-16 fighter jets. Their pilots said the 737 captain was not in the cockpit and the co-pilot appeared to have fainted in his seat. They later saw two people in the cockpit apparently trying to regain control of the plane. The fighter pilots also saw released oxygen masks and said the aircraft was making constant right-hand turns to show it had lost radio contact. A Greek government spokesman said there was no sign of a hijacking or terrorism. Rescue workers are now concentrating on the grisly task of identifying the charred corpses of all the passengers. At Larnaca airport distraugt relatives waited for news. They will now have to wait for the results of an investigation into what caused this accident. The black box data recorder has been found, the voice recorder is still missing. Problems involving Helios Airways have been reported in the past. One aircraft lost cabin pressure last year and three passengers were hospitalised.