CREATE TABLE table_18712423_3 (original_air_date VARCHAR, directed_by VARCHAR, written_by VARCHAR)

What is the original air date of the episode directed by Ian Barry and written by Philip Dalkin?
SELECT original_air_date FROM table_18712423_3 WHERE directed_by = "Ian Barry" AND written_by = "Philip Dalkin"
SELECT "original_air_date" FROM "table_18712423_3" WHERE "Ian Barry" = "directed_by" AND "Philip Dalkin" = "written_by"