When did the episode titled "Winterland" air for the first time? 
CREATE TABLE "table1_13426649_1" (
  "num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "production_code" text,
  "u_s_viewers_millions" text
);
SELECT "original_air_date" FROM "table1_13426649_1" WHERE "title"='\"Winterland\"';