Su-30 Flanker-C [Russia]
The Sukhoi Su-30 Flanker-C is a two seater variant of the Su-27 Flanker-B. Though essentially not a trainer, the Su-30 is in some ways more relevant and practical for an air force (like the Indian Air Force) than the Su-27 Flanker-B. One such point is the fact that by having a weapon systems officer the pilot will be in a better position to engage enemy in a more hostile environment. But the primary reason for the IAF was that by having two pilots in the aircraft that experiences 9-G forces, the chances of the officers losing control due to "blackouts" is reduced.