CREATE TABLE table_30378 ("No. in series" FLOAT, "No. in season" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" FLOAT)

What was the air date of the episode with the production code of 322?
SELECT "Original air date" FROM table_30378 WHERE "Production code" = '322'
SELECT "Original air date" FROM "table_30378" WHERE "Production code" = '322'