Oracle PL/SQL Tutorial/Date Timestamp Functions/SYS EXTRACT UTC
SYS_EXTRACT_UTC(x) converts the TIMESTAMP WITH TIMEZONE x to a TIMESTAMP containing the date and time in UTC.
SQL>
SQL> SELECT SYS_EXTRACT_UTC(TIMESTAMP "2005-05-13 19:15:26 PST") FROM dual;
SYS_EXTRACT_UTC(TIMESTAMP"2005-05-1319:15:26PST")
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14-MAY-05 02.15.26.000000000 AM
SQL>