Моля, опитайте това, надявам се, че ще помогне.
DELETE FROM departure, departure_time
USING departure
INNER JOIN departure_time
WHERE departure_date = '2016-09-30'
AND departure_time.id = departure.id
Или
DELETE FROM departure, departure_time
USING departure
INNER JOIN departure_time
WHERE departure_date = '2016-09-30'
AND departure_time.departure_id = departure.id
Или можете да използвате ON DELETE CASCADE
това ще свърши работа автоматично за вас.