Thirteen years after a prototype took to the skies, HAL’s intermediate jet trainer HJT-36 Sitara project has gone into a tailspin.

The Indian Air Force has told Hindustan Aeronautics Ltd to address basic flaws in its design. The trainer, IJT in official parlance, must be made capable of recovering from stall and spin, the IAF has informed the Bengaluru-based public sector major manufacturer. “You cannot fly an aircraft that can’t spin and recover from it. They have to return to the drawing board and make it work,” a senior IAF officer told on condition of anonymity. The IAF has expressed its displeasure over long delays at HAL, besides the aircraft’s inability to meet its requirements.

The project, begun in 1999, was hit by a series of accidents and a change of engine. The first prototype took to the skies in 2003 and six prototypes are now operational. “It is an aerodynamic or design flaw. It cannot be rectified unless they start all over again,” the officer said. That means the project will be delayed further.The Air Force is already looking to buy training aircraft from abroad to replace its ageing fleet of Kirans, inducted four decades ago. HAL, however, maintains the project is on track. “The IJT project is at an advanced stage of development. We have made necessary modifications in the aircraft to meet all the IAF’s requirements,” a senior HAL official stated in an email to Express. He said a majority of tests have been completed.

The next step is to test the spinning capabilities of the aircraft, scheduled for August end, he said. “After completion of stall testing, BAe Systems directed us to increase the roll inertia by adding mass at the wing tips to achieve the desired spin characteristics. We carried out the modifications,” the official added. He claimed the performance of the aircraft after the modifications was satisfactory.

Stall and Spin

Military pilots are trained to do different manoeuvres, including stalling and spinning an aircraft and recovering from it.

Stall and spin are conditions in which an aircraft starts losing altitude rapidly and controls become ineffective. When an aircraft goes into a spin, it goes out of control and starts auto-rotating and descending rapidly, nose up. During combat flying, any aircraft can inadvertently get into a spin or stall, so pilots are trained to get it into such situations and recover safely without abandoning the aircraft.