Tracking data shows the plane was in the air for about 10 minutes when it abruptly descended 9,000ft (2,700m), with passengers telling local media they heard "some kind of explosion".
A Greek hospital official said a 61-year-old Serbian national was being treated for friction burns. "His wife held onto his legs for around five minutes to stop him from being sucked out," Michalis Giannakos said.
In a statement, Ryanair said its Friday morning flight from the Greek city of Thessaloniki to Germany's Memmingen returned "shortly after take-off when a passenger window dislodged in flight".
"The aircraft landed normally and passengers returned to the terminal. One passenger requested and received medical assistance on the ground in Thessaloniki," the Irish budget airline said.
It added that "a replacement aircraft was arranged to bring passengers to Memmingen" several hours later.
Passengers have told local media the man was left hanging head first out of the window as far as his shoulders before other passengers managed to pull him back inside.
Those on board have also said the window was smashed by pieces of the jet's engine - although Ryanair has not commented on this.
"We immediately realised there had been a decompression. There were screams... for a moment I thought someone had accidentally opened the emergency door," Christina, a fellow passenger, told Radio Thessaloniki.
"The masks dropped and there was a strong smell. The head and shoulders of one passenger were outside the window. Fortunately, he hadn't taken off his seat belt."
https://www.bbc.co.uk/news/articles/cgk65knkyzdo
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