user: Question: What it Duration, when Test Flight is Free flight #3?
Columns: ['Test flight', 'Date', 'Speed', 'Altitude', 'Crew', 'Duration', 'Comment']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Taxi test #1', 'February 15, 1977', 'mph (km/h)', 'taxi', 'none', 'taxi', 'Concrete runway, tailcone on']
SQL:

assistant: SELECT "Duration" FROM "Table" WHERE "Test flight" = 'Free flight #3';