On April 28, 2013, a Wizz Air Airbus A320-232 took off from Warsaw then descended rapidly from about 11000ft.
Passengers smelled smoke. A passenger named Barbara was quoted (machine translation) “Zachybota?o plane dropped like a machine. Then I felt a burning smell. Other passengers can feel it. After a while we went to the employee. Were informed that there was a failure”
Pilots notified ATC and turned around to return to Chopin Airport. The airport said that Pilots said this was not an emergency landing.
There were 161 passengers aboard. They disembarked without any problem, and were provided a later Wizz flight to London.

V Air flight ZV-252 had to return and make an emergency landing in Taipei, Taiwan, on May 6th.
American Eagle flight 5946 had to divert and make an emergency landing at Louisville International Airport, Kentucky, on September 25th.
JetBlue flight B6-1274 made an emergency landing at John F. Kennedy International Airport, New York, on September 2nd.