It's from Debka but I'm posting it anyway for the record. On the main thread it is mentioned that Israel issued some sort of warning to Greece:
http://www.debka.com/
Greek army chief does not rule out hijack of Cypriot Helios airliner that crashed north of Athens with 115 passengers and 6 crew aboard Sunday. No sign yet of survivors.
August 14, 2005, 12:47 PM (GMT+02:00)
Two pilots reported incapacitated before crash. Greek F-16 pilot escorting the plane from Larnaca said, according to one report, one pilot was not visible and co-pilot seen collapsed. A second report claimed both were slumped in their cockpit seats before the crash. Greek air force jets were scrambled into the air when the Cypriot plane from Larnaca signaled it was in trouble and Athens international airport went on emergency footing. DEBKAfile: Until the cause of the crash is determined, Middle East and Mediterranean airports have gone on high terror alert for possible air hijacks
And, as usual, we don't know why but we know it's not terrorism.