Chandigarh: The Indian Air Force (IAF)’s recent accident involving a Sukhoi Su-30MKI multi-role fighter in Assam, in which both pilots died, has revived long-standing concerns over the reliability and operational readiness of the service’s premier combat aircraft.The March 5 incident also recalls a period a decade earlier, when multiple engine-related problems in the twin-engine Su-30MKI fleet had forced the Ministry of Defence (MoD) to publicly acknowledge persistent technical shortcomings in what is widely regarded as the backbone of the IAF’s combat aviation inventory.Since this fighter type was inducted into IAF service in 1997, the force has lost around 13-14 Su-30MKIs in accidents, resulting in five pilot fatalities, including the two who died in the latest crash. The IAF has ordered an inquiry into the latter incident, though official sources said it could take considerable time to conclude and that its findings are almost certain to remain classified.In this context, it is pertinent to recall that in March 2015, then-defence minister Manohar Parrikar had informed parliament that the IAF’s Su-30MKIs were grappling with frequent engine failures and poor operational serviceability. His statement followed several minor and major accidents involving the Russian-origin fighter which then was being licence-built by Hindustan Aeronautics Limited (HAL) at its Nashik facility.Parrikar revealed that between January 2013 and December 2014, the IAF had recorded technical problems in 35 NPO Saturn AL-31FP engines that power the Su-30MKI, which too were being licence-built by HAL at Koraput in Odisha. The late defence minister also elaborated on failures that were attributed largely to faulty engine bearings and low lubricating-oil pressure.He stated that metal fatigue in the power pack’s bearings – designed to reduce friction between moving parts – caused them to chip or fragment under operational stress. These microscopic metallic particles then ‘contaminated’ the oil flow inside the engine, triggering mechanical disturbances that could potentially lead to the fighters’ mid-air failures.Of 69 Su‑30MKI engine malfunctions investigated since 2012, Parrikar told parliament that 33 were traced to metal chips detected in the oil system, while 11 were linked to abnormal engine vibrations and eight incidents were attributed to low oil pressure. The remaining 17 cases, however, were not publicly explained.Despite the Su-30MKI’s formidable capabilities – including thrust-vectoring engines, a long combat radius and advanced avionics – its operational availability at the time was also far less impressive. Parrikar disclosed that only around 110 aircraft – roughly 55% of the fleet then – were operationally ready and indicated that steps were being taken to raise this figure to around 70%.The IAF was unavailable for comment on whether availability levels had since improved significantly or just marginally or not at all.To address these fighter engine issues, Parrikar said its original equipment manufacturer had proposed nine technological improvements to HAL, aimed at enhancing reliability, including improved lubrication systems to reduce metal erosion, better bearing fits and the use of better-quality oil.According to the MoD, these modifications were incorporated into 25 newly manufactured AL-31FP engines, reportedly enhancing both performance and durability. Consequently, whereas earlier engine malfunctions typically tended to occur after around 500 flying hours, the improvements extended this interval to some 900 hours before similar issues emerged.Online sources indicate that Russia marketed the AL-31FP engines to the IAF with a mean time between overhauls (MTBO) of around 1,000 hours and a total service life of roughly 3,000 hours. In practice, however, early units reportedly required overhauls much sooner – after 300-500 hours – resulting in lower readiness and increased maintenance cycles. Such shorter service intervals compared unfavourably with several Western-origin engines, which typically offered longer MTBOs and higher reliability.Lower MTBOs and frequent overhauls also meant more aircraft grounded at any given time, limiting peak sortie rates and the ability to sustain high-tempo combat platform operations.Fighter aviation industry officials said that the AL-31FP power pack, though highly capable and equipped with thrust-vectoring – providing enhanced maneuverability – was never designed for the extreme heat and demanding operational environments encountered across India. Recurrent service failures, vibration problems and maintenance demands suggested that the original Russian design – adapted for Indian specifications – required further refinement for sustained local operations.These concerns later fed into discussions between Indian and Russian officials on the long-delayed “Super Sukhoi” modernisation programme. Conceived in 2006, the plan initially aimed to upgrade around four squadrons – roughly 80-84 of the IAF’s fleet of some 260 fighters, mostly licence-built by HAL – into near 4.5-generation platforms with enhanced avionics, sensors and weapons. Nearly two decades later, however, the project awaits approval within the MoD’s byzantine decision-making system.Under this planned fighter upgrade, the platforms would be equipped with the indigenous Uttam active electronically scanned array radar, replacing the ageing NIIP N011M Bars, along with new electronic warfare (EW) suites, advanced mission computers and upgraded cockpit systems to enhance network-centric operations.The Super Sukhois are also expected to integrate the indigenous Astra beyond-visual-range missile and the air-launched BrahMos-A cruise missile, extending strike reach and lethality. Additional improvements under discussion include limited radar-signature reduction and upgraded avionics to address obsolescence, while enabling future weapons integration.In late 1996, the MoD had signed a $1.5 billion contract with Russia for 50 Sukhoi Su-30 fighters that included standard Su-30K export variants, which lacked many of the features that later defined the Su-30MKI configuration. The subsequent Su-30MKI variant was a uniquely customised platform integrating Russian airframe design with avionics and subsystems sourced internationally, including radar and avionics contributions from Thales Group of France and EW and targeting systems from Elbit Systems of Israel.Some years later, the IAF returned 18 of the early Su-30K aircraft to manufacturer Irkutsk Aviation Plant in Siberia under a swap arrangement, replacing them with the more advanced Su-30MKIs.For its part, HAL began assembling its first Su-30MKI fighter from Russian kits in late 2004, following a license-production agreement signed four years earlier. Full indigenous production, with aircraft built entirely from scratch, rather than kits, commenced in 2013, while HAL’s Koraput division began manufacturing the fighters’ AL-31FP engines alongside.Over time, 272 Su-30MKIs were inducted into the IAF’s inventory, though around 13-14 were lost to attrition. To partly offset these losses, the MoD signed a Rs 13,500 crore contract with HAL in late 2024 for 12 additional Su-30MKIs, incorporating around 62.6% indigenous content as part of the government’s Atmanirbhar Bharat initiative to expand domestic defence equipment and platform manufacturing.In conclusion, the March 5 Su-30MKI accident in Assam once again highlights the enduring challenges of operating a high-performance fighter in demanding conditions. The fighters’ early engine issues reflected the difficulties of adapting imported technology to extreme environments, maintenance realities and strategic dependencies. And while reliability has, no doubt, improved over time, each such loss inevitably affects operational efficiency, underscoring the IAF’s continuous task of keeping its most advanced fighters fully mission-ready.