There seems to be a lot of missing correct answers to this one: "When is our bus leaving?", "When is our bus departing?", and doubtless a bunch more. Reported...
Nope, i put when does our bus leave instead of depart and was marked incorrect. Very frustrating as i would never say depart.
What is happening with the translations in English??? Usually wrong!!!
It's part of the separable verb abfahren, meaning "to depart". Obviously that has a different meaning to fahren ("to drive").
Wann fährt unser Bus? - Is more colloquial but also works fine. The ab is actually often left out. Other otion would be: Wann fährt unser Bus los? :o)
When is our bus leaving is a far more common way of saying this than when does our bus depart