What is the aircraft for 21 crews?
CREATE TABLE table_23508196_5 (
    type_of_aircraft VARCHAR,
    number_of_crews VARCHAR
)
SELECT type_of_aircraft FROM table_23508196_5 WHERE number_of_crews = "21"
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 aircraft for 21 crews? ### Input: CREATE TABLE table_23508196_5 (
    type_of_aircraft VARCHAR,
    number_of_crews VARCHAR
) ### Response: SELECT type_of_aircraft FROM table_23508196_5 WHERE number_of_crews = "21"