What is the original air date of the episode directed by Terrence Nightingall?
CREATE TABLE table_21627 (
    "Series #" real,
    "Season #" real,
    "Title" text,
    "Directed by" text,
    "Written by" text,
    "Original air date" text
)
SELECT "Original air date" FROM table_21627 WHERE "Directed by" = 'Terrence Nightingall'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: What is the original air date of the episode directed by Terrence Nightingall? ### Input: CREATE TABLE table_21627 (
    "Series #" real,
    "Season #" real,
    "Title" text,
    "Directed by" text,
    "Written by" text,
    "Original air date" text
) ### Response: SELECT "Original air date" FROM table_21627 WHERE "Directed by" = 'Terrence Nightingall'