The Chengdu FT-7BGI is a 2013 trainer variant of the Chengdu J-7, a Chinese fighter derived from the Soviet MiG-21 design. It was manufactured specifically for the Bangladesh Air Force by the Chengdu Aircraft Corporation. The crash on 21 July was the sixth involving an F-7 variant in Bangladesh since a 1998 incident in Dhaka that killed the pilot. The aircraft's age and the BAF's continued reliance on the model had drawn criticism for years, driven by what investigative journalist Zulkarnain Saer Khan described as "economic necessity, established infrastructure, and slow procurement of modern aircraft." Sagar himself had logged roughly 60 hours on the FT-7BGI and over 100 on the PT-6 trainer. He had completed advanced training in aerospace medicine in India and been promoted to flight lieutenant in 2024. None of that experience could overcome a mechanical failure at low altitude with a school directly below.

The timeline is merciless. Takeoff at 13:06. Malfunction and stall shortly after. The aircraft became unresponsive. The control tower's instruction to eject -- impossible at that height. Sagar's attempt to divert toward open ground -- unsuccessful. Impact at 13:12 into the main gate of the Haider Ali Building. CCTV footage captured the jet striking the roof of the school's seven-storey Block 7 before plunging into the lower building, creating a hole at the gate and igniting a fire. The Bangladesh Fire Service arrived at 13:22, deploying nine units and six ambulances. A coach from the Dhaka Metro was pressed into service to transport victims to hospitals. Authorities later collected bags, shoes, and identity cards of children from the wreckage. The aircraft's debris was removed by nightfall.

Among the dead was Maherin Chowdhury, a teacher at Milestone School. When the jet hit and fire swept through the classrooms, Chowdhury ran into the burning building. She pulled students out, then went back in again, and again. She rescued more than 20 children before the burns that would kill her became too severe. She died in hospital. In all, 32 students, three teachers, and the pilot were killed. At least 173 people received treatment, many of them children under 12 with severe burns. Sixty victims were taken to the National Institute of Burn and Plastic Surgery. Twenty-eight went to the Combined Military Hospital. The government declared 22 July a day of national mourning, flags at half-mast across Bangladesh. The Ministry of Education later established an annual bravery award for teachers in Chowdhury's name.

The investigation committee's final conclusion pointed to pilot operational error causing loss of control, though the BAF initially attributed the crash to mechanical failure. But the public fury that followed focused on a broader question: why was a military training flight being conducted over one of the most densely populated cities on Earth? Aviation analysts noted the risks of operating fighter jets near Hazrat Shahjalal International Airport, which serves both military and civilian traffic. Students staged demonstrations at the Bangladesh Secretariat demanding accountability, transparency about the true death toll, decommissioning of outdated aircraft, and relocation of air force training away from Dhaka. On 12 August, families of the victims formed a human chain at Milestone College. The committee's key recommendation was straightforward: for public safety, all initial Air Force training should be conducted outside Dhaka. The question was whether it had taken the deaths of 32 schoolchildren to make that recommendation obvious.