On August 2018, which day had the highest number of cancelled flights due to the most serious reasons in Dallas/Fort Worth International?
On August 2018 refers to FL_DATE like '2018/8%'; day with the highest number of cancelled flights refers to MAX(COUNT(FL_DATE WHERE CANCELLED = 1)); cancelled due to the most serious reasons refers to CANCELLATION_CODE = 'A'; in Dallas/Fort Worth International refers to Description = 'Dallas/Fort Worth, TX: Dallas/Fort Worth International';
SELECT T2.FL_DATE FROM Airports AS T1 INNER JOIN Airlines AS T2 ON T1.Code = T2.ORIGIN WHERE T2.FL_DATE LIKE '2018/8%' AND T1.Description = 'Dallas/Fort Worth, TX: Dallas/Fort Worth International' AND T2.ORIGIN = 'DFW' AND T2.CANCELLED = 1 AND T2.CANCELLATION_CODE = 'A' GROUP BY T2.FL_DATE ORDER BY COUNT(T2.FL_DATE) DESC LIMIT 1
database name:db_id airline
Air Carriers table Air Carriers Cols: Code dtype integer, Description dtype text, 
Airports table Airports Cols: Code dtype text, Description dtype text, 
Airlines table Airlines Cols: flight date dtype text, operator carrier airline id dtype integer, tail number dtype text, operator carrier flight number dtype integer, origin airport id dtype integer, origin airport sequence id dtype integer, origin city market id dtype integer, ORIGIN dtype text, destination airport id dtype integer, destination airport sequence id dtype integer, destination city market id dtype integer, destination dtype text, scheduled local departure time dtype integer, departure time dtype integer, Departure delay dtype integer, departure delay new dtype integer, arrival time dtype integer, arrival delay dtype integer, arrival delay new dtype integer, CANCELLED dtype integer, cancellation code dtype text, scheduled elapsed time dtype integer, actual elapsed time dtype integer, carrier delay dtype integer, weather delay dtype integer, National Aviavtion System delay dtype integer, security delay dtype integer, late aircraft delay dtype integer, 
