user: Question: When "The Charlotte Letter" is the title what is the air date?
Columns: ['Series #', 'Season #', 'Title', 'Director', 'Writer(s)', 'Original air date']
Types: ['real', 'real', 'text', 'text', 'text', 'text']
Sample row: [15.0, 1.0, '"The Second Greatest Story Ever Told, Part 1"', 'John Landis', 'Marta Kauffman and David Crane', 'July7,1991']
SQL:

assistant: SELECT "Original air date" FROM "Table" WHERE "Title" = '"The Charlotte Letter"';