An Easyjet Europe Airbus A320-200, registration OE-IVC performing flight U2-4603 from Berlin Schoenefeld (Germany) to Thessaloniki (Greece), was climbing out of Berlin when the crew stopped the climb at FL150 but continued in the general direction to Thessaloniki. The aircraft crossed into Poland, attempted to climb but stopped again at about FL165, turned around at the Polish/Czech border about 180nm southeast of Berlin and returned to Berlin now descending to FL100. The aircraft landed safely back at Schoenefeld Airport about 90 minutes after departure.
A replacement A320-200 registration OE-ICI reached Thessaloniki with a delay of 5 hours.
The occurrence aircraft is still on the ground in Berlin about 9.5 hours after landing back.