Flight 847 was pushing back when its wing tip "made contact" with a parked aircraft, the company said.
Passengers and crew deplaned while both airlines were taken out of service for inspection, according to AA.
"We apologize to our customers for the inconvenience this caused, and our team is working to get them on their way as soon as possible," the airline wrote in a statement.
No injuries were reported on the plane or on the ground, they added.
The OAG website shows Flight 847 departed from PHL at 2:35 p.m., about four hours later than originally scheduled.
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