Conveyance port restrictions require calling only at notified customs ports; alternative landings allowed only for unavoidable causes. Conveyance movements are restricted to locations designated as customs ports, customs airports, land customs stations, inland container depots, or air freight stations; unloading of imports and loading of exports is permitted only at such notified places. The Principal Commissioner or Commissioner may approve specific unloading/loading places and set customs area limits. The person in charge of a vessel or aircraft shall not call or land at non notified places without the Board's approval, except when compelled by accident, stress of weather, or other unavoidable cause.