Database: airline
Question: How many hours in total did all of the Delta Air Lines aircraft were delayed due to a late aircraft in August of 2018? Identify the plane number of the aircraft with the highest delayed hours.
SQL: SELECT T1.TAIL_NUM, SUM(CAST(T1.LATE_AIRCRAFT_DELAY AS REAL) / 60) AS delay FROM Airlines AS T1 INNER JOIN `Air Carriers` AS T2 ON T2.Code = T1.OP_CARRIER_AIRLINE_ID WHERE T1.FL_DATE LIKE '2018/8/%' AND T2.Description = 'Delta Air Lines Inc.: DL' ORDER BY delay DESC LIMIT 1