Per favore, prova questo, spero che ti aiuterà.
DELETE FROM departure, departure_time
USING departure
INNER JOIN departure_time
WHERE departure_date = '2016-09-30'
AND departure_time.id = departure.id
Oppure
DELETE FROM departure, departure_time
USING departure
INNER JOIN departure_time
WHERE departure_date = '2016-09-30'
AND departure_time.departure_id = departure.id
Oppure puoi usare ON DELETE CASCADE
che funzionerà automaticamente per te.