"When is their departure?"

Translation: Hvornår er deres afrejse?

[HommeRenoir]

I am not sure but should "afgang" not be accepted here?

[Jnwulff]

It should

[ErikKristiansen]

departure is as well afrejse as afgang. E.g. departure by flight equals the Danish word "afgang"

[OrchidBlack]

Hvornår vs når?

[klisterable]

Hvornår is more of a question. "Hvornår kører bussen?" "hvornår havde du fødslesdag?"

[hovis6]

"afgang" ??