CREATE TABLE table_17868 ("#" FLOAT, "Episode" TEXT, "Writer" TEXT, "Director" TEXT, "Viewers ( millions ) " TEXT, "Original airdate" TEXT)

What's the original airdate of the episode directed by Pete Travis?
SELECT "Original airdate" FROM table_17868 WHERE "Director" = 'Pete Travis'
SELECT "Original airdate" FROM "table_17868" WHERE "Director" = 'Pete Travis'