NEW DELHI: As the first anniversary of the Air India Boeing 787 crash in Ahmedabad approaches, key questions over what caused the disaster that killed 260 people remain unanswered, as investigators are set to miss the formal one-year deadline for a final report.According to Bloomberg, India’s Aircraft Accident Investigation Bureau (AAIB) will not be able to complete its full findings by the deadline because critical technical analysis, including examination of the aircraft’s engines in the United States is still underway.Instead, the AAIB is expected to issue a status report this week, explaining the reasons for the delay and outlining the progress of the investigation. A final report is now expected within the next three months.The probe involves coordination with international aviation authorities and manufacturers, including the US National Transportation Safety Board, Boeing and GE Aerospace, as engineers continue to analyse the aircraft’s engines and related systems.Officials have said the engine examination is being carried out in the US due to the specialised equipment required to dismantle and assess the components.Under international aviation rules, a final accident report is expected within 12 months. However, if this is not possible, authorities are required to issue an interim update outlining progress and outstanding issues.A preliminary report released last year found that both engine fuel control switches moved from ‘RUN’ to ‘CUTOFF’ moments after take-off, cutting fuel supply and causing both engines to shut down.A brief cockpit exchange between the pilots suggested confusion over how the switches were moved. This detail has created confusion whether there was pilot action or a technical malfunction.Investigators are also examining the timing of the aircraft’s Ram Air Turbine (RAT) deployment, an emergency system that activates when power is lost. Experts say the timing could be crucial in determining whether an electrical failure played a role.Another key challenge in the investigation is the condition of the aircraft’s recorders. While data from the forward flight recorder has been recovered, the rear recorder was severely damaged and could not be accessed using standard methods.Investigators are also expected to explain why the aircraft’s Emergency Locator Transmitter did not activate after impact, as well as review any outstanding maintenance issues on the aircraft before departure, including a reported defect in its core network system.The London-bound Air India flight AI-171 crashed shortly after take-off from Ahmedabad’s Sardar Vallabhbhai Patel International Airport on 12 June last year striking a medical college hostel complex.The crash killed 241 people on board and 19 on the ground, leaving just one survivor, making it one of the deadliest aviation disasters in recent years.