The plane's banner read: "Resign Bishop Zubik."
Someone rented the aircraft, but there's no word yet on the identity of that person or group of people.
There have been calls for Bishop Zubik's resignation since the release of the state grand jury report into the sexual abuse of children in six of Pennsylvania's diocese, including Pittsburgh and Greensburg.
The report cited 301 priests, clergy and lay teachers with credible allegations against them. There were 99 in the Diocese of Pittsburgh alone.
The report led to the resignation of former Pittsburgh bishop, Cardinal Donald Wuerl, the Archbishop of the Diocese of Washington DC.
Earlier this month, Bishop Zubik said he wanted to stay on in Pittsburgh despite the calls for him to step down.
"I have to say, I have really prayed about my future. I want to say that I want to continue as bishop of Pittsburgh," he said.
So far, there's been no comment from the Pittsburgh Diocese about the plane.
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