CREATE TABLE table_31248 ("No. in series" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" FLOAT)

What date did the episode that was directed by Christian i. nyby ii originally air on?
SELECT "Original air date" FROM table_31248 WHERE "Directed by" = 'Christian I. Nyby II'
SELECT "Original air date" FROM "table_31248" WHERE "Directed by" = 'Christian I. Nyby II'