Rules of the Air Article 69
If no position report or landing information is received from a small aircraft conducting VFR flight, 5 minutes after its estimated time over reporting point or 30 minutes after its estimated time of arrival, the unit providing VFR Flight Following service shall execute a communication search and shall notify the search and rescue facility to conduct a physical search and rescue when the communication search is completed or 15 minutes after the communication search is initiated and the aircraft has not been located.
中文原文 飛航規則第69條
負責目視飛航通訊追蹤之航管單位於目視飛航小型航空器預計通過位置報告點五分鐘後或預計到達時間三十分鐘後，未獲得位置報告或降落資料時，應即實施通信搜索，並於完成通信搜索或通信搜索開始後十五分鐘仍未獲得該航空器確實消息時，即應通知有關單位採取搜救行動。