NEWS
On August 4, while on a visit to Pune, Chief of the Air Staff Air Chief Marshal N.A.K. Browne revealed that the Indian Air Force (IAF) had identified a ‘design flaw’ with the Russian-made supersonic fighter aircraft Su-30 MKI. “We have identified a ‘fly-by-wire’ problem with the aircraft. It is a design issue and we have taken it up with the design agency,” he explained. The Air Chief was speaking to the reporters on the sidelines of a function held to mark the Golden Jubilee Celebrations of the Armed Forces Medical College (AFMC) where he also released a postal stamp to commemorate the AFMC Golden Jubilee.

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Air Chief ‘Charlie’ Browne was obviously referring to the December 13, 2011 crash of a Su-30 MKI fighter aircraft. While the two pilots managed to eject safely, the problems of a design flaw resurfaced during the ensuing Court of Inquiry, instituted by the IAF.

After a flawless flight safety record spanning more than a decade since its induction into service in 1997, it was on April 30, 2009, the IAF lost its first Su-30 MKI. Since then, two more ‘Sukhois’ have been lost in accidents. Interestingly, two of the three CAT-I accidents were attributable to malfunction of the fly-by-wire (FBW) systems. But what were the causes of malfunctions/failures?

The Su-30 MKI’s aerodynamic construction is an unstable longitudinal tri-plane that confers its unprecedented agility. Like most modern jet fighters, this highly unstable platform is manoeuvred by computer-controlled FBW system. Multi-layered backup systems are necessary as without the FBW, the aircraft cannot be manually controlled by the pilots. To ensure near-ultimate safety, the Su-30 MKI’s FBW system is endowed with quadruple redundancy. If one of the FBW channels becomes faulty, it automatically gets disconnected from the system, suitably warning the crew to take appropriate actions. A level-1 failure does not jeopardise the mission, while a level-2 failure would demand a diversion to the nearest suitable airfield. With so much in-built redundancy, a level-3 failure would normally be rarer than one in a million possibility which unless quickly rectified could lead to the loss of aircraft.

If the above be true, how did the IAF land up in a situation losing two Su-30 MKIs within a span of less than three years due to FBW system malfunctions? The Court of Inquiry constituted for the first accident found the accident was caused by the incorrect position of critical switches behind the pilots outside their field of view. The aircraft crashed when a crucial FBW switch was toggled disabling the flight control system. Was it therefore, a self-inflicted tragedy?

The findings of the December 2011 accident, are yet to find their way into the public domain. However, if incorrect positioning of the switches is once again established to be the cause of the accident, it would be evident that corrective actions in the aftermath of the first accident—that of inhibiting the identified crucial switches—did not prove to be fully effective. The fact that the second accident occurred soon after take-off, the possible wrong positioning of the switches on the ground itself may have escaped the pilots’ attention, as they continue to be located outside the pilots’ normal field of view. Was this “the design defect’ that was alluded to by the CAS during his Pune trip?