O'Leary told analysts at Ryanair's April-to-June results presentation on July 20 that the initial indication pointed to "foreign object damage to the engine on takeoff" from Thessaloniki but that the airline could not yet confirm it, Reuters reported.
He linked the cabin depressurization to a suspected fan blade problem.
The Boeing 737-800 operating flight FR1879 was climbing out of Thessaloniki toward Memmingen, near Munich, when passengers heard a loud bang. A window failed, the cabin lost pressure, and oxygen masks dropped.
A woman aboard told Greek broadcaster Radio Thessaloniki that most passengers were asleep and woke to a sound like a bursting tire.
Flight-tracking site AirNav Radar said the aircraft turned back at about 16,000 feet, or roughly 4,900 meters, and landed safely in Thessaloniki about an hour after departure, CNN reported.
