The Su-27 Flanker never came anywhere near getting a single kill against any Western type of aircraft.
Caught myself reading some internet article about the Su-27 Flanker, and what a über-super-turbo fighter jet it is… or should be. Sure, serious people are always going to advise me, ‘Tom, but everybody knows one can’t trust the internet’. Well, the mass of consumers can’t care less.
One of reasons they can’t care less is simply the lack of research. If there would be more of serious research, and related publications, it would be known – already since at least a decade – that a) details of the Su-27’s weapons and weapons-systems have been compromised to the CIA by one of their designers, Adolf Tolkachev, already before they ever entered service, and that b) in real combat the Su-27 proved to be anything else than ‘ideal’ as an air superiority fighter.
Video-games in particular are no reality: nothing even roughly comparable to it. For example, the Su-27 could be the capable of mimicking manoeuvres of a fly, while having an ‘endless’ range/endurance and whatever else. All great, super, and classy. However, in real combat all of that proved to be of no use. In real combat, decisive factor was the poor cockpit ergonomics and complex avionics, combined with the fact that the aircraft was still depending on ages-old R-27s (yes, these were compromised by Adolf Tolkachev, too). Primary issue is nearly always that of actually finding and detecting the target: even a reasonably advanced LD/SD-radar/weapons system (like that on the Su-27) is not ‘always and 1000% reliably’ going to detect a ‘target’ moving within its detection & engagement envelope (as this is shown in video games).

On the contrary: in the case of such systems like on vanilla Su-27, it’s not going to do that in even 50% of cases. Moreover, even once it detects and tracks a target, there is always the issue of IFF. This remains anything else than ‘100% reliable’. This is why diverse Su-27s over the time became involved in diverse incidents with civilian aircraft, or shoot down wingmen during test-firings, or failed to intercept low-flying MiG-29s etc. One of reasons was how were they used, another was their (poor) cockpit ergonomics. For example: detection of targets depends heavily on the use of the ‘right’ working mode of the radar – which in turn depends on the circumstances in the given moment. On the single-seat Su-27, the pilot had to do all the related decisions on his own, while still flying the aircraft and actually ‘fighting’, too. Well, this proved a nearly impossible task – because of poor cockpit ergonomics (i.e. switching the working modes of the radar wasn’t easy, selecting the necessary range wasn’t easy etc., etc., etc.).
Unsurprisingly,
– the type never came anywhere near getting a single kill against any Western type of aircraft;
– and its most serious test was Ethiopian deployment of Su-27s during the Badme War against Eritrea, fought 1998-2001.

Now, to keep a long story short, the Ethiopians tended to operate their Su-27s in pairs during that war. A Su-27UB crewed by an Ethiopian pilot – often with a Russian advisor in the back seat – was there to control the situation and help and advise the (Ethiopian-crewed) single seater. If a Russian was on board, the Su-27UB was strictly forbidden from going anywhere near the combat zone: it had to stay several dozens of kilometres away from it.
But, that was perfectly enough: the battlefields of the Badme War were rather small, and inexperienced Eritreans operated in a predictable way. Thus, two of their MiG-29s got shot down, and the air war was decided, once and for all. Related descriptions are meanwhile available in form of the book Ethiopian-Eritrean Wars, Volume 2.
At least as unsurprising is that after the end of the Badme War, the Ethiopians placed a big follow-up order, though this time they demanded Su-27UBs only…
…while the Sukhoi rushed to apply about 15,000 diverse changes to the Su-27 (resulting in Su-27SM and sub-variants)…
Photo credit: Digital Combat Simulator and Sukhoi