CREATE TABLE table_55171 ("Home team" TEXT, "Home team score" TEXT, "Away team" TEXT, "Away team score" TEXT, "Venue" TEXT, "Crowd" FLOAT, "Date" TEXT)

What date did Carlton play as the away team?
SELECT "Date" FROM table_55171 WHERE "Away team" = 'carlton'
SELECT "Date" FROM "table_55171" WHERE "Away team" = 'carlton'