Door Falls Off Bono's Learjet During Flight to Germany

— -- A private plane carrying U2 lead singer Bono experienced an in-air incident Wednesday, with a rear door falling off the Learjet 60, an official with the German Federal Bureau of Aircraft Accident Investigation said.

“The Learjet lost a door where the luggage was put in,” the official, Germout Freitag, told ABC News.

Freitag said authorities don't understand why the door flew off.

"There can be many reasons for this incident. Either something broke on the door or the door wasn't closed properly. Those are the usual problems that occur," Freitag said.

The plane, which took off in Dublin, was able to land safely and no injuries were reported. The incident was under investigation, and it could take a year for authorities to complete their final report, Freitag said.

Bono was traveling to Berlin for the Bambi Awards, where his band was being honored and was slated to perform. After arriving in Germany, the musician and activist met with Walter Lindner, the country's special representative for the fight against Ebola, to talk about the deadly virus.

Aviation expert and ABC News consultant John Nance said Bono’s plane situation is uncommon, but didn't pose much of a hazard for the plane’s passengers.

“What happened here is very unusual, but they were never really at risk,” Nance said. “The passengers may have been scared when they heard a noise, but they never lost pressurization.”