Where human remains are transported—
(a) by sea, then in order to prevent movement, the impervious coffin shall be packed in an ordinary wooden case, or in a case made of any other material, or shall be placed in a specially designed container made of fabric;
(b) by road, the impervious coffin shall be conveyed on a closed hearse, closed van or other motor vehicle and shall be so placed as to prevent movement;
(c) by air, the impervious coffin may be conveyed in the baggage compartment of a passenger aircraft or in a cargo aircraft and may be equipped with a vent or safety valve if precautions are taken to prevent the excape of liquids or nauseous gases.