民航意外調查機構是香港特區政府運輸及房屋局(運房局)轄下的獨立機構，由總意外及安全調查員領導，專責調查在香港發生或涉及在香港註冊的民用飛機在香港以外地方發生的意外和嚴重事故，以及加強和推廣民航安全。副總意外及安全調查員直接向總意外及安全調查員匯報，職責包括—

(a) 協助總意外及安全調查員領導和管理民航意外調查機構，包括統籌員工調配、員工培訓、採購和保養調查設備、設施保養和檔案管理等工作，以及制訂優化意外和事故調查及安全管理程序的策略和措施，以確保香港能隨時根據《香港民航(意外調查)規例》(第448B章)及《國際民用航空公約》(《附件13》)進行飛機意外和事故調查；
(b) 在總意外及安全調查員不在任及／或進行海外職務訪問／培訓期間，代理其職務，包括代替總意外及安全調查員，履行《香港民航(意外調查)規例》(第448B章)下的法定職能和行使所賦予的法定權力；
(c) 協助總意外及安全調查員監督相關航空安全資訊及數據的收集、保護和分析工作，以期找出安全隱患，並向業界發放航空安全訊息，以提升安全及作教育用途；
(d) 按總意外及安全調查員的指示進行飛機意外／事故調查或監督由其他調查員進行的調查；以及協助總意外及安全調查員，在有需要時為海外航空意外調查機構提供支援及專業意見(例如在海外發生的意外或事故涉及在香港註冊的飛機)；
(e) 協助總意外及安全調查員監督定期檢視和更新與飛機意外和事故調查相關的法例、安排及程序，以確保香港能隨時根據《香港民航(意外調查)規例》(第448B章)及《國際民用航空公約》(《附件13》)進行意外和事故調查；
(f) 代表香港特別行政區政府參與有關航空意外和事故調查及航空安全的國際組織及活動，並與國際組織在相關議題上保持密切聯繫；以及
(g) 協助總意外及安全調查員監督向航空意外的生還者及遇難者／傷者家屬匯報的工作(如調查進度、有關意外調查的資訊等)。

The DCASI is the deputy head of Air Accident Investigation Authority (AAIA), an independent authority under the Transport and Housing Bureau (THB) of the Government of the HKSAR responsible for the investigation of accidents and serious incidents which occur in Hong Kong or which involve Hong Kong-registered civil aircraft outside Hong Kong, and the enhancement and promotion of civil aviation safety. Reporting to Chief Accident and Safety Investigator (CASI), the responsibilities of the DCASI include –

a) To assist CASI in leading and managing AAIA, including staff deployment, staff training, procurement and maintenance of investigation equipment, facility maintenance and record management, etc., as well as to formulate strategies and measures to enhance accident and incident investigation and safety management procedures, thereby ensuring Hong Kong’s capability and readiness in conducting aircraft accident and incident investigations in compliance with the Hong Kong Civil Aviation (Investigation of Accidents) Regulations (CAP. 448B) and Annex 13 to the Convention on International Civil Aviation;

b) To deputize CASI during his/her absence and/or his/her overseas duty visits/training, including standing in CASI’s capacity to carry out the statutory functions and exercise the statutory powers granted under the Hong Kong Civil Aviation (Investigation of Accidents) Regulations (Cap. 448B);

c) To assist CASI in overseeing the collection, protection and analysis of relevant aviation safety information and data with a view to identifying potential safety hazards and disseminating aviation safety messages to the industry for safety improvement and education purposes;

d) To conduct aircraft accident/incident investigations or supervise investigations conducted by other investigators as directed by CASI; and to assist CASI in providing support and professional advice to overseas air accident investigation authorities when necessary (e.g. when aircraft registered in Hong Kong are involved in accidents or incidents occurred overseas);

e) To assist CASI in regularly reviewing and updating the legal provisions, arrangements and procedures for aircraft accident and incident investigations, in order to ensure Hong Kong’s capability and readiness in accident and incident investigations in compliance with the Hong Kong Civil Aviation (Investigation of Accidents) Regulations (Cap. 448B) and Annex 13 to the Convention on International Civil Aviation;

f) On behalf of the Government of the HKSAR, to participate in international organisations and activities in relation to air accident and incident investigations and aviation safety; and to maintain close liaison with international organisations on relevant issues; and

g) To assist CASI in supervising the reporting (e.g. progress of investigation, information relating to the accident investigation) to be made to survivors and families of victims of air accidents.