CREATE TABLE table_50294 ("Parameter" TEXT, "1st stage" TEXT, "2nd stage" TEXT, "3rd stage" TEXT, "4th stage" TEXT)

What is the third stage that has the first phase of 5,443kg?
SELECT "3rd stage" FROM table_50294 WHERE "1st stage" = '5,443kg'
SELECT "3rd stage" FROM "table_50294" WHERE "1st stage" = '5,443kg'