Rules of the Air Article 31

A flight plan shall be submitted before departure, to an air traffic services reporting office or, during flight, transmitted to the appropriate air traffic services unit or air-ground control radio station, unless arrangements have been made for submission of repetitive flight plans.Unless otherwise required by the CAA, a flight plan for a flight to be provided with air traffic control service shall be submitted at least sixty minutes before departure, or, if submitted during flight, at a time which will ensure its receipt by the appropriate air traffic services unit at least ten minutes before the aircraft is estimated to reach:1. the intended point of entry into a control area or advisory area; or2. the point of crossing an airway or advisory route.
中文原文 飛航規則第31條
除已依規定提報之長期飛航計畫者外,飛航計畫應於航空器起飛前向飛航服務單位提報;如於飛航中,則向適當飛航服務單位或陸空通信電台提報。
除民航局另有規定外,需飛航管制服務之飛航,應在起飛前六十分鐘提報飛航計畫。
如在飛航中提報,應確保適當飛航服務單位在該航空器預計到達下列位置點前至少十分鐘收到飛航計畫:
一、進入管制區域之位置點。
二、通過航路之位置點。

English translation for reference only; the Chinese text prevails. Not legal advice.