The HTT 40, a project that was funded by HAL through its own internal funds after the IAF had initially refused to take part, is now seen by the force as a game changer and progress made in “record time”.

“The successful implementation of the project in record time is a big relief. We now hope for the delivery schedule to be met,” a source in the defence establishment said.

The new aircraft will be part of the first stage of training for the IAF pilots – basic training – and will eventually replace the Swiss-made Pilatus aircraft bought in 2012.

The IAF pilots go through three stages of training using three different kinds of aircraft before they move on to fighters.

HAL sources said that the all-metal aircraft, which is powered by Honeywell engines, has about 55 per cent indigenous content. 

Asked about the high cost per aircraft of about Rs 90 crore each (if one calculates the contract value to total number of planes ordered for), HAL sources said that actual cost is less than Rs 50 crore a piece and the extra cost is towards the spares, training and infrastructure costs besides other expenses.

The HTT 40 has features like running changeover of pilots, hot-refueling, zero-zero ejection seats, multi-function displays, night flying capabilities and a range of 1,000 km with a top speed of 450 kmph.

All the tests required for certification were completed in six years from the first flight that took place in May 2016.

In November 2019, former IAF chief Air Chief Marshal R. K. S. Bhadauria had flown in the HTT-40 during which he reviewed its flying characteristics including the six-spin routine.

Next up is Intermediate Jet Trainer (IJT)

Defence sources said the next step for the IAF is the Intermediate Jet Trainer (IJT) which will replace the ageing Kiran aircraft used for Stage 2 of training.

Both Stage 1 and Stage 2 of training last for six months each before the pilots move onto the next stage which is for about one year on board the Hawk jets.

Sources explained that because of the depleting number of trainers, the IAF was forced to use limited numbers of Kiran and even Pilatus for Stage 2 of training.

It was in January that the IAF pilots successfully demonstrated the IJT’s capability to carry out six turn spins to the Left Hand and Right Hand sides.

Though the IJT had completed demonstration of its capabilities in terms of altitude and speed envelope, load factor, satisfactory stall characteristics and limited armament capability as required by the IAF much earlier, successful spin test was pending.

During spin testing in 2016, the aircraft departed from controlled flight which brought the programme to a temporary halt, the HAL had said in a statement, adding that it decided to proceed further using its internal resources to complete the critical spin testing.

Basic training saga

Till the IAF decided to go in for the Pilatus aircraft, a deal which is mired in controversy over allegations of kickbacks, the IAF pilots used to do their first stage of training on board HAL manufactured Hindustan Piston Trainer-32 (HPT-32).

The aircraft was grounded in 2009 following several crashes and engine failures. That is when the IAF went in for the Pilatus deal for 75 aircraft.

In its 2019 report, the Comptroller and Auditor General of India (CAG) was critical of the Rs 2,895.63 crore deal, saying that incorrect price calculations had worked in the firm’s favour.

The audit report said that the Switzerland-based Pilatus Aircraft got the deal despite failing to commit to transfer of technology for maintenance, and was allowed to tweak its offer at a later stage for an advantage over competitors. The firm also didn’t offer a seamless supply of spares, it added.

The 2012 deal has been under the scanner of the Central Bureau of Investigation (CBI) since it was flagged by the defence ministry while it was under Manohar Parrikar. However, in January 2016, the Defence Acquisition Council (DAC) approved the procurement of 38 PC-7 Mk-II trainers from the Swiss company after a strong pitch from the IAF.

The government then cancelled the proposed deal for additional Pilatus aircraft in 2019, after the HTT-40 cleared crucial trials.

However, suspension of business with Pilatus affected the maintenance of the existing fleet since spare parts were unavailable.

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The aircraft was piloted by Gp Capt (retd) HV Thakur and Gp Capt (retd) A Menon. HAL CMD R Madhavan said: “Given the right resources and backing, HAL is capable of designing products that can meet any requirement of Indian armed forces.”

Mr Arup Chatterjee, director (engineering and R&D) added that by demonstrating its capability to have six turn spins on both sides the IJT has achieved a major milestone. “The success can be attributed to the synergy between designers, flight operations and certifying agencies,” he said, adding that with the completion of spin certification of HTT-40 and the progress achieved in IJT, HAL will soon have the state-of-the-art trainers for stage I and II training of IAF pilots.

The IJT, which was conceived by HAL as a replacement to the ageing Kirans of IAF fleet, had completed demonstration of its capabilities in terms of altitude and speed envelope, load factor, satisfactory stall characteristics and limited armament capability as required by IAF, earlier.

“…The only pending task was spin testing. During the course of spin testing, in 2016, the aircraft departed from a controlled flight which brought the programme to a temporary halt. However, HAL decided to proceed further using its internal resources to complete the critical Spin testing,” HAL said in a statement.

The PSU added that the capability to enter and recover from spin is a necessity for a trainer aircraft in order to familiarise the trainee pilot to recognise departure from controlled flight and the actions required to recover from such situations.

“Achieving satisfactory characteristics during spin and an assured recovery from spin form a part of very crucial flight tests due to its unpredictability. The spin flight testing is inherently a high-risk maneuver and therefore progresses incrementally turn by turn. Due to the complex interplay of aerodynamic and inertia forces, the motion of the aircraft in spin is unpredictable and flight testing is the only way to assess the acceptability or otherwise of its characteristics,” HAL added.

Pointing out that spin flights are carried out in good weather conditions with a team of designers, flight test engineers and safety pilots monitoring various parameters during the flight, HAL said, it was, therefore, time-consuming.

“Several flight tests are required to be carried out before six-turn spin flights are undertaken as well as a number of flights are further required before full spin certification is achieved,” it added.

Subsequent to the temporary halting of flight tests in 2016, HAL undertook major modifications like shifting the vertical tail aft on the airframe and increasing the rudder area and flight testing resumed in April 2019.

These modifications entailed the use of a new Anti-Spin Parachute system (ASPS) which is mandated for the safety of the aircraft and test crew during spin flight testing. The new ASPS was integrated into the aircraft in July 2020 and the successful streaming of the parachutes were demonstrated in September 2020. HAL commenced the stall and spin testing of the IJT in its new modified configuration in November 2020.

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