New Delhi: India has just begun the spin flight tests on the indigenous Intermediate Jet Trainer, or just IJT that is designed and developed by the nation’s long aircraft maker, to replace an ageing fleet of another locally made aircraft of the air force.

State-run Hindustan Aeronautics Limited‘s (HAL’s) test pilots Group Captain H. V. Thakur (Retired) and Wing Commander P. Avasti (Retired) are conducting the spin flight testing in Bengaluru.

“The spin testing of an aircraft is the most crucial phase of its flight testing. Accordingly, the testing will be gradually progressed to assess the behaviour of the aircraft till six turn spins to either side to meet the targeted requirement,” a statement from HAL said.

The IJT has already been tested to its full envelope in terms of speed, altitude and load factor (‘g’ envelope) and has also been integrated with drop tanks as well as bombs. For spin test, HAL redesigned the aircraft by moving the vertical tail aft and extending the rudder surface.

“These changes, for ensuring a satisfactory spin behaviour, required extensive redesign of the rear fuselage and the rudder. The changes have been incorporated in two aircraft with the involvement and clearance from certification agencies at every stage,” HAL said.

Post modification, the two aircraft underwent significant flight tests to assess the general handling with the new configuration of fin and rudder. These aircraft have now been incorporated with the necessary safety devices (Anti-Spin Parachute Systems).

During the first flight, initially the aircraft was taken through one-turn spin to the left and right each to test the spin characteristics, the statement said.

Developed internally by HAL, IJT was at one point in time considered as a viable alternative to the now retired fleet if Kiran MkII aircraft that were used by the Indian Air Force (IAF) for its intermediate training of its pilot cadre.

However, since the project began in 1999, there were serious deficiencies in the IJT that had caused serious accidents to its prototypes in 2007 during the AeroIndia show in Yelahanka air base that year, and again in 2008 during test flights.

However, the IAF has always felt the need for the IJT, as its current three-state pilot training module’s first and the third phases are being taken care of by the Pilatus PC-7 MkII and the BAE Systems‘ Hawk Advanced Jet Trainers, before the fighter pilots move on to the supersonic jets.

This need was brought out by the IAF in a 2014 Request for Information to global trainer aircraft vendors. The HAL had also sought outside help to see if the IJT’s weight could be reduced further. However, it is to be seen if it continues to show interest in the HAL’s IJT programme.

The IJT project was almost given up by HAL due to lack of interest from IAF, but was revived in 2015, but the unsatisfactory spin flight tests in 2016 had resulted in further troubles with the programme, causing a three-year further delay. The project got back on track again in April 2019 when it was flight tests, this time successfully.

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