Republic Airways Emergency Descent

A Republic Airways Embraer ERJ-175 on behalf of American Airlines, registration N101HQ performing flight AA-4599 from Philadelphia,PA to Savannah,GA (USA), was enroute at FL340 about 160nm south of Philadelphia when the crew performed an emergency descent to 10,000 feet due to the loss of cabin pressure and levelled off at 10,000 feet about 6 minutes later (average rate of descent 4000fpm). The aircraft returned to Philadelphia for a safe landing about 50 minutes after leaving FL340. A replacement Embraer ERJ-175 registration N401YX reached Savannah with a delay of 4:40 hours. The occurrence aircraft ferried to Pittsburgh and is still on the ground in Pittsburgh about 46 hours after landing in Philadelphia.