Greece ? The Cypriot plane that crashed and killed all 121 people aboard flew on autopilot to its Athens destination – but passed thousands of feet above the airport runway, the chief accident investigator told The Associated Press Thursday.

Helios Airways Flight ZU522 then turned toward the sea, flying in a holding pattern for more than an hour before changing course again and crashing into a mountain north of Athens.

Chief investigator Akrivos Tsolakis told AP that an air traffic control diagram showed the plane had flown on automatic pilot to the Greek capital’s international airport.

“What troubles us is that the automatic pilot was functioning up to a certain point, and then it was disengaged, possibly by human action,” Tsolakis said.

Investigators are examining whether the 115 passengers and six-member crew aboard the Boeing 737-300 had lost consciousness, possibly just after takeoff. The aircraft appears to have flown from Cyprus to Athens on autopilot – a flight of about an hour and a half.