CREATE TABLE table_908 ("No. in series" TEXT, "No. in season" TEXT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Storyboarded by" TEXT, "Original air date" TEXT, "Production code" TEXT)

When did the episode with series number 29a originally air?
SELECT "Original air date" FROM table_908 WHERE "No. in series" = '29a'
SELECT "Original air date" FROM "table_908" WHERE "No. in series" = '29a'