I've just checked with S&MO who lay the buoys and not all danger areas are marked. Fixed firing ranges are marked at their extremities. Mariners and aviators are expected to avoid them by reference to the relevant chart and activity is notified by NOTAM. Be clear that danger areas are not prohibited areas. If an aeroplane or vessel is damaged in a danger area, it is the Captain's responsibility. The Service involved, though, would probably suspend operations under its duty of care and attempt to notify the "infringer" of the peril it was in. A range safety launch, where we still have them, is not a police service. How one stands legally with regard to placing an aircraft or vessel in danger, particularly if carrying passengers, is another matter altogether.