user: Question: What aircraft was introduced in 2004 and has a retired of —?
Columns: ['Aircraft', 'Introduced', 'Retired', 'Seating', 'Notes']
Types: ['text', 'real', 'text', 'text', 'text']
Sample row: ['Airbus A319-100', 2004.0, '—', '156', 'In service']
SQL:

assistant: SELECT "Aircraft" FROM "Table" WHERE "Retired" = '—' AND "Introduced" = 2004.0;