Aircraft Flight Operation Regulations Article 267

Aircraft operated in the Taipei FIR shall be equipped with a transponder capable of reporting its call sign and pressure-altitude, unless approved by CAA.
中文原文 航空器飛航作業管理規則第267條
飛航台北飛航情報區之航空器應裝置具有顯示航機班號及高度功能之航管雷達迴波器。
但經民航局核准者,不在此限。

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