What was found
AIRCRAFT WAS GROUNDED: ON DESCENT AIRCRAFT WAS UNABLE TO FOLLOW RNAV ALTITUDE THOUGH ALL 3 ALTIMETERS APPEARED TO READ CORRECTLY. WE GOT THE MESSAGE TO SWITCH FROM STANDARD ALTIMETER TO LOCAL ALTIMETER AT 23000 FEET INSTEAD OF 18000. AT 5000 FEET WE GET ECAM CAB PR SAFETY VALVE OPEN AND LO DIFF PRESSURE WARNINGS DP WAS -0.3, VS -150, CAB ALT 4600 SAFETY VALVE SHOWED OPEN ON PRESSURE PAGE. **SUPPLEMENTAL REPORT WILL BE SUBMITTED** (OPEN)