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Trainer aircraft

The saga of the indigenous creation of an ab initio propeller driven trainer aircraft and an initial jet trainer (IJT) aircraft for the Indian Air Force and the Indian Navy by the Hindustan Aeronautics Ltd reads like the script of a farce. HAL started the process of “indigenization” of these two types of trainer aircraft with the Pushpak propeller-driven trainer and the Kiran jet trainer. A young flyer learned the basics of flying on the Pushpak (both within the armed forces as well as in the many flying clubs operating across the country). The next step was to fly the Kiran jets to become acquainted with the intricacies of flying under subsonic jet power. These two projects were supposed to create a bank of technological capabilities that would enable HAL to improve the flying envelop of its future products. One had hoped that India would have acquired a large measure of self-sufficiency in one of the most fundamental requirements of military flying (the civilian benefits would be collateral advantages).

Lacking expertise

The Pushpak basic trainer was first flown by HAL  in 1958. The jet trainer Kiran (HJT-16)was inducted into service by the IAF in 1968. Having taken the first baby steps in military aviation one saw with admiration the upgradations incorporated to suit emerging military needs especially in the case of the Kiran jet trainer. It graduated from plain Kiran to Kiran I production series to Kiran IA with two hardpoints for weapons training to Kiran II with five hardpoints.

The first sign of trouble on the horizon was the mass grounding of the follow-on basic trainer Deepak (HPT-32) built around a Lycoming engine had to be finally scrapped after 17 crashes that killed 19 pilots. India’s hopes of reviving a nascent military aircraft industry began to disappear when the basic propeller trainer was replaced by the Swiss Pilatus PC-7 Mark2.

The HAL’s attempt to use its acquired expertise to create a follow-on intermediate jet trainer to replace the Kiran with work on the HJT-36 “Sitara” appeared jinxed from the very start.

The British Hawk had already been inducted to replace the Kirans. The IAF was not keen to have to fund the research and development to be conducted by HAL and other defence laboratories under the DRDO. The first hurdle that was put up on the path of the “Sitara” was that its Snecma engine was not powerful enough to fully fit the flight envelope of the intended jet trainer. A second French engine with a higher thrust was inducted but never delivered and so HAL had to fall back upon a Russian (ex-Soviet) engine.

With over 800 test flights including sea level trials, night flying trials, high altitude trials as well as weapon and drop tank trials all being successfully cleared what appears to be an insurmountable hurdle has arrived. For securing the Final Operational Clearance (FOC) all that was left to do was refine the stall characteristics which would lead to the final spin test. It now turns out, however, that what should have been detected at the very start and rectified before going into the testing phase was suddenly sprung on a bewildered nation.

The excuse to scuttle the Final Operational Clearance for the Sitara intermediate jet trainer with acceptable weapons capabilities is that it must first remove the “inherent asymmetry” that had been a part of it since its birth on the drawing board. Without this correction it would not be possible to work on the stall characteristics and hence the final spin test cannot be conducted. It is a Catch 22 kind of situation whereby if HAL does manage to rectify the “inherent asymmetry” it would have to redo all the tests all over again because this would be a new fuselage. Going by the timeframes that have occurred so far it could well be that the Sitara will get its Final Operational Clearance only after another decade. By which time the aircraft would have entered obsolescence because there would already be a fully functional jet trainer in the fleet.


If there is any lesson that HAL and the Defence Research and Development Organisation can learn from this fiasco it is that it would be more appropriate to first create a dedicated power plant capable of being employed in creating a trainer aircraft. By now HAL and the DRDO laboratories should be having a compendium of algorithms required for such a project (and given that they have had so much acquired capability from licensed production of foreign engines and aircraft). It is time that the nation begins to benefit from the many years spent in the licensed production regime instead of diving into it again and again with eyes wide open. At this rate and in this manner India is never going to achieve any semblance of “self reliance” let along “self-sufficiency” in major high value weapons platforms-the original equipment manufacturers have a way of manipulating prices of spare parts and knowhow-that India will remain hooked to dependence on these sources for its weapons platforms.

Former Chairman of HAL often on record protested the manner in which foreign vendors tend to exploit their customers by hiking the price of spares at crucial moments. R K Tyagi while projecting the HTT-40, a basic turboprop trainer that the company has conceptualised as “India’s showcase product” had pointed out that the indigenous product would ensure a favourable supply chain management  for the next thirty years.

Trainer aircraft tend to enjoy long tenures in air forces around the globe because much of what the new recruits need to learn about the emerging modern battlefield can be incorporated within the glass cockpit and upgraded from time to time. Simultaneously too, nearly all the maneuvers from takeoff and landing to dogfights and ground attack-both in attack and defensive mode-can be taught in simulators based on the ground.

While aviators insist that there is no better way to learn to fly an aircraft and its many intricacies is to learn to “fly by the seat of one’s pants”. That may have been true in the past but does not stand scrutiny in the face of the many new training and simulation methodologies that have become part of the curriculum of air warriors.