A TAROM Boeing 737-700, registration YR-BGI performing flight RO-306 from Frankfurt/Main (Germany) to Bucharest Otopeni (Romania) with 91 people on board, was enroute at FL390 about 20nm southwest of Brno (Czech Republic) when the crew initiated an emergency descent due to the loss of cabin pressure. The aircraft continued into the direction of Romania and diverted to Timisoara (Romania) for a safe landing about 50 minutes after leaving FL390. Maintenance determined the indication had been false, a faulty sensor was identified. A replacement Boeing 737-700 registration YR-BGF is positioning to Timisoara to take the passengers to Bucharest.