user: Question: What is the lowest commenced operations that has a NOUVELAIR callsign?
Columns: ['AIRLINE', 'AIRLINE (in Arabic)', 'ICAO', 'CALLSIGN', 'COMMENCED OPERATIONS']
Types: ['text', 'text', 'text', 'text', 'real']
Sample row: ['Karthago Airlines', 'قرطاج للطيران', 'KAJ', 'KARTHAGO', 2001.0]
SQL:

assistant: SELECT MIN("COMMENCED OPERATIONS") FROM "Table" WHERE "CALLSIGN" = 'NOUVELAIR';