Originally Posted by
michael_v
My best guess would be South African Airways.
Doh! Still, this might be better for the OP with AF (KE miles) out of IAD since it's a pure one-stop itinerary. SA's IAD-JNB stops in DKR, so even if there's space on that flight (looks OK near end-of-schedule, but not so good coming back), it adds an extra connection.