Aircraft Accident Investigation Bureau
The Aircraft Accident Investigation Bureau (AAIB) of India recently released a preliminary report on the Air India flight AI 171 crash in Ahmedabad. The report revealed that both engine fuel control switches changed from ‘RUN’ to ‘CUTOFF’ within seconds after take-off. This unexpected switch-off led to the loss of engine power and the crash that killed 241 of the 242 onboard. The investigation has raised questions about cockpit procedures and the functioning of aircraft controls. This incident marks the critical role of the AAIB in probing aviation accidents and improving safety standards.
International Framework for Aircraft Accident Investigation
Aircraft accident investigations follow rules under the Chicago Convention of 1944. This global treaty governs civil aviation and is overseen by the International Civil Aviation Organization (ICAO). ICAO sets technical standards and protocols for investigations through Annex 13. The country where the accident occurs, called the ‘State of Occurrence’, leads the investigation. Other involved countries include the aircraft’s State of Registry, State of Operator, State of Design, and State of Manufacture. This ensures a coordinated and transparent inquiry process.
Establishment and Mandate of the AAIB
India’s AAIB was formed to separate accident investigations from regulatory functions. Before 2012, the Directorate General of Civil Aviation (DGCA) handled investigations. To maintain independence, the AAIB was established under the Ministry of Civil Aviation. It investigates accidents and serious incidents involving aircraft over 2,250 kg or turbojet aircraft. The bureau’s primary aim is to prevent future accidents, not to assign blame or liability.
Investigation Process and Evidence Collection
Upon notification of an accident, AAIB investigators are dispatched to the site immediately. They gather perishable evidence such as wreckage samples and retrieve black boxes—the Cockpit Voice Recorder (CVR) and Flight Data Recorder (FDR). The evidence is analysed in collaboration with domain experts and laboratories, including those of Hindustan Aeronautics Limited and the DGCA. The AAIB has unrestricted access to all relevant information without needing prior permission from judicial or government bodies.
Reporting and Recommendations
After thorough analysis, the AAIB prepares a draft report reviewed internally. The Director General approves the final report, which is then made public on the AAIB website. The report is also shared with ICAO and other involved states. The AAIB issues safety recommendations to the DGCA and international aviation regulators. These suggestions aim to enhance aviation safety and prevent recurrence of similar incidents.
Significance of Black Boxes in Investigations
Black boxes are crucial in understanding accident causes. The CVR records cockpit conversations and sounds. The FDR logs flight parameters such as speed, altitude, and control inputs. Together, they provide objective data that help reconstruct the sequence of events leading to a crash. The AI 171 preliminary report’s focus on fuel control switches was made possible by analysing these devices.
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