user: Question: What callsign has commenced operations in 2011?
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 "CALLSIGN" FROM "Table" WHERE "COMMENCED OPERATIONS" = 2011.0;