Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_1952 ( "No. in series" real, "No. in season" real, "Title" text, "Directed by" text, "Written by" text, "Original air date" text, "Production code" text )

### Question ###
What was the original air for the 06-03-521 production code?

### Accurate SQL ###

SELECT "Original air date" FROM table_1952 WHERE "Production code" = '06-03-521'